Note: Descriptions are shown in the official language in which they were submitted.
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International Patent Application Filed under the
Patent Cooperation Treaty
For
PIG AND METHOD FOR
APPLYING PROPHYLACTIC SURFACE TREATMENTS
By
Leonid V. Budaragin,
Mark A. Deininger,
Mikhail Pozvonkov,
Norman H. Garrett, and
D. Morgan Spears II
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of priority under PCT Chapter I,
Article 8, and 35
U.S.C. 119(e) of U.S. Provisional Application No. 61/161,635 entitled, "Pig
and Method
for Applying Prophylactic Surface Treatments" filed on March 19, 2009, which
is
incorporated herein by reference in its entirety. This application is a
continuation-in-part and
also claims benefit of priority under PCT Chapter I, Article 8, and 35 U.S.C.
365(c) of U.S.
Non-Provisional Application No. 12/100,910, entitled, "Pig and Method for
Applying
Prophylactic Surface Treatments" filed on April 10, 2008, which is
incorporated herein by
reference in its entirety. The '910 application is a continuation-in-part of
International
Application No. PCT/US07/81230, entitled, "Method for Proving Prophylactic
Surface
Treatment for Fluid Processing Systems and Components Thereof' filed on
October 12,
2007, which in turn claims benefit of priority of U.S. Provisional Application
No.
60/851,354, entitled, "Method for Proving Prophylactic Surface Treatment for
Fluid
Processing Systems and Components Thereof' filed on October 12, 2006. Both the
'230
International Application and the '354 Provisional Application are
incorporated herein by
reference in their entireties as well.
FIELD OF THE INVENTION
[0002] This invention relates to processes and apparatus used for applying
coatings to the
internal passageways of a fluid process system, particularly tubes and pipes.
DESCRIPTION OF THE RELATED ART
[0003] Metal tubes are often used in a variety of industrial processes.
Oftentimes there is a
need to reduce damage to the inner surfaces of metal tubes in heat exchangers,
process
systems and similar equipment due to corrosion, erosion, debris accumulation,
or a
combination thereof. To this end, a protective coating is often the preferred
solution.
[0004] There exist many devices for coating the interior of a pipe. Methods
included in the
prior art include brushing, swabbing, spraying, and others. Devices and
methods for brushing
on an interior coating on a pipe are disclosed in U.S. Pat. Nos.: 2,048,912;
2,334,294;
2,470,796; 2,551,722; 2,792,807; 2,800,875; and 3,516,385. Those patents
disclose methods
suitable for coating pipes at their points of manufacture. The technologies
described therein
are not practical for coating pipes that are already assembled into useful
components such as
heat exchangers, industrial process plants, fluid transport assemblies, or
other final-use
applications of pipes. There is a need for a method to coat pipes that are
already assembled
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and "in the field," either prior to their first use, or after a period of
service has already
occurred and it is desirable to apply a coating to "aged" pipes that have been
cleaned.
[0005] Prior art surface coatings for industrial process systems often fall
short of providing
erosion, corrosion, or debris accumulation protection for many processes,
particularly those
involving high temperatures or highly caustic materials or a combination
thereof.
Particularly, there exists a need in the petrochemical industry for a surface
coating that can be
applied to an assembled process system with minimum disruption to the
industrial plant and
with minimum downtime, and which results in a coating that is resistant to
highly deleterious
conditions.
[0006] An additional limitation of the current art in pipe coatings is the
thickness of the final
protective layer. Due to the wide temperature swings present in many
industrial processes,
the mismatch in coefficient of thermal expansion between the pipe material and
the coating
material typically results in cracking and spalling of current coatings,
especially for thicker
coatings.
[0007] Metals, ceramics, glasses, and cermets are used to construct many
functional items
that are in turn used in carrying out industrial processes. Under certain
operating conditions
of these processes, surface degradation of a component can result from many
causes. These
can include the corrosive nature of particular process conditions, thermal
effects of the
process or environment, contamination from various elements becoming deposited
on the
surface or infiltrating into the material, deposits formed by catalytic
activity between the
component's material and the process fluid, galvanic activity between the
component's
material and the process fluid, concentration cell corrosion, crevice
corrosion, graphitic
corrosion, and a combination of these degradation mechanisms with each other
or with other
mechanisms.
[0008] During operation, various industrial process systems suffer degradation
to the
working sections of the system being attacked by various chemicals and
conditions. This
occurs in the oil industry, colorants industry, cosmetics industry, food
industry,
pharmaceutical industry, chemical industry, and within closed systems such as
cooling
systems, heating and air conditioning systems, and many others. Additional
systems that are
affected by surface degradation are furnaces, boilers, internal combustion
engines, gas turbine
engine systems, rockets, etc. In any continuous or intermittent process system
there is the risk
of surface degradation due to the exposure of materials to certain chemicals
and conditions.
The surfaces exposed to the process may degrade due to the material itself
degrading,
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eroding, or corroding, or the degradation may be in the form of deposits that
accumulate on
the material, affecting performance of one sort of another, e.g. flow
efficiency through a pipe.
Any kind of degradation is generally referred to as "fouling." The typical
solution to these
types of fouling is to upgrade the material used to construct the functional
item, be it a pipe, a
heat exchanger, etc. For example, a pipe may be constructed of a nickel alloy
stainless steel,
rather than of common carbon steel, in an attempt to improve its inner and
outer surface
longevity and/or functionality. As another example, tanks used to hold various
chemical
materials may experience material deposits or reactions on the inner surface
of the tank,
which can adversely affect the overall process efficiency. In another example,
a heat
exchanger may be made from a high nickel content alloy to allow it to
withstand high
temperature operation (as in the case of a hydrocarbon-fuel gas turbine
system) while also
reducing the amount of precipitates and deposits that might be occurring due
to the caustic
environment in which the heat exchanger is required to operate. In yet another
example, an
exhaust valve for use in an internal combustion engine may be made from a
particular alloy
in an effort to reduce the amount of carbon deposits forming on its surface;
carbon deposits
are a well known source of operational and emission problems for internal
combustion
engines.
[0009] Many industrial processes use materials to contain and transport
various fluids,
slurries, or vapors, and those materials can become degraded during use. These
problems are
known as "flow assurance" issues, which is the industry term for the growth of
flow
restrictions in various pipes, tubes, heat exchangers, and process containers,
etc. For
instance, the interior of a pipeline used in an industrial process may have
its effective cross-
sectional area reduced during operation by deposits from the chemicals carried
within the
pipe during various processes. In other cases, the vaporous or liquid elements
carried within
a heat exchanger may precipitate the growth of crystalline deposits if
favorable conditions
(temperature, pressure, presence of catalytic elements, etc.) exist within the
system. In one
example of this problem, crystals of various elements may grow during fluid
processing
operation because certain exposed molecules within the material surface of the
interior of a
conduit serve to catalyze the growth of some types of fibers on the interior
wall of the
conduit. For example, carbon fibers grow on the interior of metal pipes used
for ethylene
transport, petro-chemical cracking tubes, petroleum refinery heaters, natural
gas turbine
blades, propane and LPG transport tanks, etc. While the mechanism of carbon
fiber
formation is not entirely clear, it is believed that exposed iron or other
atoms at the surface of
a steel or iron pipe in, e.g., a petroleum processing facility, may play a
role in decomposing
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hydrocarbons flowing in the pipe into carbon. Because carbon has some
solubility in iron, a
steel or iron pipe may absorb this carbon. When the pipe material becomes
saturated with
carbon, amorphous carbon fibers begin to grow rapidly at process temperatures
in the range
of about 400 C to about 800 C. Such deposits and/or fibrous growths affect the
boundary
layer development of the fluids and/or vapors passing through the pipe's
interior, and can
cause a significant restriction in the pipe's ability to transfer fluids,
vapors, or slurries.
Furthermore, a corrosive environment, especially due to the presence of water
and impurities
or salts dissolved in it, causes corrosion of metal pipes leading to eventual
failure. Also, it is
known that petrochemical process fluids flowing through a metal tube at high
temperature
can cause metal wastage in what is known as metal dusting, wherein the tube's
inner surface
is eroded by various mechanisms. Accordingly, there is a need in the art for a
way to prevent
or significantly inhibit the growth of carbon fibers while at the same time
inhibiting chemical
attack of corrosive elements on the substrate, such as those that result in
metal dusting of
components within a system.
[0010] All throughout industry, passageways and chambers regularly experience
deposits on
their interior surfaces caused by precipitates of the production fluids,
deposits exacerbated by
high temperatures, solidification of matter in slow moving boundary layers,
and deposits
occurring by various other mechanisms. Some components, such as heat
exchangers, can
experience deposits from the processed fluid and from the heat exchange
medium, thereby
experiencing fouling on multiple interior surfaces. In some cases, more than
one interior
surface contacts hydrocarbons being processed, such as in a heat exchanger
that transfers heat
from processed material to feed material. Other components, such as pipelines,
can suffer
corrosion on outer surfaces due to process and/or environmental factors. The
repairing of
such problems has large costs associated with it due to interruption of
production while
sections of a process system are identified and then cleaned, bypassed, and/or
replaced. The
petroleum industry, for example, has literally thousands of miles of
connective pipelines,
tubes, manifolds, as well as thousands of heat exchangers and process risers,
etc. that require
regular maintenance and repair at great costs to the industry. For example,
shutting down a
petroleum refinery to repair and/or replace flow restricted pipes results in
losses of
approximately $200,000 to $500,000 per day of lost output.
[0011 ] In another example, at high process pressures and at temperatures
above 0 C, methane
gas, present in the petrochemical stream may react with water to form ice-like
structures
called hydrates. Hydrate formation in production-stream flow lines in the
petroleum industry
is also of great concern. Production-stream flow lines carry the raw, produced
fluids from the
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wellhead to a processing facility. If a flow line is operated in the "hydrate
region" (i.e., under
conditions at which hydrates can form in an oil or gas wellstream), hydrates
can deposit on
the pipe's inner wall and agglomerate until they completely block the flow
line and stop the
transport of hydrocarbons to the processing facility. Attempts to prevent
hydrate formation
typically involve injecting additives into the process fluid, but this can be
a costly solution.
[0012] Because the problem of deposits on the interior of process pipes and
tubes and the
resulting reduction in flow is so large, there are a number of industry
associations
participating in the study and improvement of flow assurance in fluid
processing systems.
For example, the Gas Technology Institute estimates that the cost of hydrate
formation
remediation to industry is over $100 million per year.
[0013] Deposits on the interior surface of a pipe have significant negative
impact on the
pipe's ability to transfer fluids or gases, and these results can vary
depending on the surface
roughness of the deposit. For example, a smooth deposit of 5% on the interior
of a pipe of
circular cross-section can cause a loss of throughput of 10%, and require a
pressure increase
of 30% to maintain constant flow. An uneven deposit of 5% can increase the
loss of
throughput to 35% and require a pressure increase of 140% to maintain constant
flow. See
Cordell, Introduction to Pipeline Pigging, 5 th Edition (ISBNO-901360-33-3).
[0014] Deposit growth on the inside of a pipe can cause deposits or growths to
become so
large as to nearly stop all fluid flow through the pipe, as shown in Figure 2.
Conditions such
as these can occur within a few months, or even within a few weeks of
operation in the case
of certain industrial processes.
[0015] In other applications, scale is caused by precipitates formed within a
process system's
enclosures during oil and gas recovery, food processing, water treatment, or
other industrial
processes. The most common scales are inorganic salts such as barium sulphate,
strontium
sulphate, and calcium carbonate. In some cases the scales may be partly
organic
(naphthenates, MEG-based etc.). Other scale formations may be composed of
sodium
chloride, iron carbonate, and magnesium hydroxide. Scales formed from
sulphates generally
are due to mixing of chemically incompatible waters (like sea water and
formation water).
Carbonate scales result from pressure release of waters containing bicarbonate
at high
concentration levels. Scaling degrades the process efficiency by plugging sand
screens and
production pipe, by causing failures in valves, pumps, heat exchangers, and
separators.
Scaling may also block transportation pipelines.
[0016] Furthermore, combustion buildup known as slag or scale often forms on
the flame-
heated surfaces of furnaces, boilers, heater tubes, preheaters, and reheaters.
The degree of
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combustion buildup depends on the quality of the fuel being burned. Clean
natural gas, for
example, produces little or no combustion buildup, while coal, a "dirtier"
fuel, produces
significant combustion buildup. In particular, coal-fired power plants
experience significant
combustion buildup on boiler vessels in contact with the coal combustion
products. That
buildup decreases heat transfer through the surface to the substance being
heated, and
therefore wastes energy. Also, such combustion buildup increases the applied
temperature
necessary to cause the substance to achieve a desired temperature. That
increased
temperature stresses the boiler vessel, and may lead to material failure.
Preventing
combustion buildup on the flame-heated surfaces of a fluid transport or
processing system
would reduce energy consumption and extend equipment lifetime.
[0017] In some applications, the surfaces exposed to fluid flow may become
degraded by the
nature of the fluid itself, for example, in the case of hydrogen transport and
containment,
which has the associated problem of hydrogen embrittlement of the exposed
materials.
[0018] Throughout industry and technology, sensors detect operational
parameters of
various processes. By necessity, those sensors inhabit the process material,
and are subject to
those fouling mechanisms inherent in the processes they monitor.
Unfortunately, even the
smallest degree of fouling may affect the accuracy of a sensor, even if that
same degree of
fouling has only a negligible effect on the process itself. Often the remedy
to sensor fouling
is to design the sensor and sensor mounting apparatus to easily replace fouled
sensors.
Sensors represent high value components, and frequent sensor replacement adds
significant
costs in addition to production loss due to shut down for sensor replacement.
[0019] The hydrocarbon process industry recognizes several distinct mechanisms
for the
fouling of process components due to the unique conditions of those processes.
One
mechanism, known as coking, results from heating hydrocarbons and driving off
lighter,
lower-boiling fractions causing thermal condensation of heavier fractions.
Asphaltenes, tars,
inorganic material, and other solids will form on the surfaces of various
petrochemical
process units. In particular, vacuum columns, fluid catalytic crackers,
cokers, viscosity
breakers, and any equipment handling heavier oil fractions at high
temperatures suffer from
the buildup of coke. Also, the high-temperature environment of an ethylene
cracker causes
polymerization of carbon-carbon double bonds, the product of which condenses
and forms
coke upon further heating. When high temperature plays a significant role and
forms high
molecular weight coke, the resulting material is called pyrolytic coke. In a
different process,
a metal species such as iron or nickel catalyses the dehydrogenation of a
hydrocarbon,
leading to what is known as catalytic coking. Elemental carbon then deposits
in the metal,
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weakening it. When the system is shut down and cooled for decoking or other
maintenance,
the weakened metal can crack or spall. In some cases, the carburized metal can
spall at
process temperatures, resulting in metal dusting mentioned above.
[0020] In addition to reducing process throughput, coke buildup decreases heat
transfer,
requiring higher process temperatures consuming more energy and lowering
equipment
lifetime. Coke deposits can cause uneven heating, forcing the use of lower
temperatures to
avoid safety issues. In addition, shutting down those systems to decoke stops
production.
System shut downs and restarts cause thermal stress and increase the
likelihood of system
malfunctions and material failure. Reducing coke buildup can extend equipment
lifetime,
improve process throughput, lower energy consumption and operating
temperatures, increase
safety, and makes less-expensive alloys available for equipment construction.
Moreover,
increasing the actual temperature of the process stream (not just the
temperature of the
outside of the heated vessels) would increase process efficiency and
throughput. As it is,
many process temperatures are limited by the metallurgy of the heater tubes.
Coke buildup
requires higher temperatures to be applied outside to obtain a given
temperature inside those
tubes.
[0021] A second distinct mechanism for fouling equipment in the hydrocarbon
industry is
corrosion by one or more chemicals present in the process stream. In
particular, hydrogen
sulfide (H2S) attacks metal surfaces, causing the formation of iron sulfates
that flake from
hydrocarbon-contacting surfaces, reducing the thickness and strength of
process equipment,
clogging passages, and potentially diminishing the activity of catalysts
downstream. The
presence of ammonia (NH3), ammonium chloride (NH4C1), or hydrogen (H and H2)
enhances
corrosive attack by H2S. Furthermore, acids such as hydrochloric acid (HC1),
naphthenic
acid, sulfuric acid (H2SO4), and hydrofluoric acid (HF) cause corrosive attack
at various
points in hydrocarbon processing systems. For example, naphthenic acid
corrosion can be
observed in process equipment handling diesel and heavier fractions, because
naphthenic
acids tend to have boiling points similar to diesel fractions. Corrosion by
sulfuric acid and
hydrofluoric acids occurs in alkylating units and associated components
employing those
acids. Protection against corrosive mechanisms may be found in using chromium,
nickel, and
molybdenum alloys, and by adding substances to the process stream such as base
to
neutralize acid. Ironically, H2S is added to process streams to reduce metal
dusting and other
forms of fouling; yet H2S itself causes corrosion. That compound also arises
during
hydrodesulfuring processes, when thiols and other naturally-present
organosulfur compounds
react to form H2S and desulfured hydrocarbons. In addition, metal systems
handling
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alternative fuels such as alcohols including methanol and ethanol have been
shown to
experience corrosion. Protecting equipment against those corrosive mechanisms
can lower
operating costs, increase run length, extend equipment life, and make less-
expensive
materials available for equipment construction.
[0022] As petroleum resources become less plentiful and more expensive,
renewable
sources of hydrocarbons increase in importance. Biodiesel, for example,
promises an
alternative fuel to petrodiesel, the fuel derived from crude oil. However,
biodiesel refining
presents unique challenges to refining equipment. Typically, a strong base
such as sodium
hydroxide or potassium hydroxide in alcohol digests triglycerides and long-
chain fatty acids
from a biological or renewable source, to form esterified fatty acids
(biodiesel) and glycerin.
That source may be corn, soy, oil palm, pulp, bark, even restaurant waste and
garbage. The
harsh basic environment required for the digestion reaction may cause caustic
stress corrosion
cracking, also known as caustic embrittlement. Heat treatments and nickel-
based alloys may
be necessary to avoid cracking, unless a less-expensive or more-effective
means can be found
to protect that equipment.
[0023] Surfaces that become contaminated with debris during process operation
often
adversely affect the efficiency and/or functionality of the process itself.
Currently, most
cleaning methods to remove deposits on interior surfaces within systems of the
types
described above in process plants involve using one or more of the following
strategies:
= Chemical solvents such as kerosene or diesel fuel, or stronger aromatic
solvents such
as xylene or toluene.
= Dispersants that act as surfactants
= Exothermic chemical reactions
= Mechanical cleaning methods such as pigging or jetting
= Thermal cleaning methods that involve hot oil or diesel fuel, or the
external
application of high heat to break down surface deposits
[0024] These methods involve considerable time and effort on the part of
process plant
maintenance personnel, reducing output or throughput of a system and causing
the associated
loss of revenue to the plant.
[0025] Similarly, in powder metal spraying operations, chemical attack occurs
within the
spraying chamber that rapidly degrades its interior surfaces. In other
applications such as
food processing, beverage production, and similar closed process systems,
material
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degradation on the interior surface of many portions of a process system
occurs due to
chemical attack, material deposits, fibrous growth, and other surface
contaminants.
[0026] Portions of fluid processing and transport systems exposed to the
environment,
especially those containing iron, also experience corrosion from environmental
factors.
Chemical, thermal, and galvanic attack represent leading mechanisms of
exterior surface
fouling in those systems.
[0027] There exists, therefore, the need for an improved means of protecting
the surfaces in
many functional components from a variety of contaminants that build up or
chemical
erosion that occurs, through various mechanisms, during the component's normal
operation.
An improved surface treatment that can be affordably applied and that provides
a
demonstrable resistance to surface contamination would serve to improve many
processes
currently in use throughout industry. The invention disclosed herein addresses
this need.
DESCRIPTION OF THE INVENTION
[0028] Various embodiments of the present invention are described herein.
These
embodiments are merely illustrations of the present invention. Numerous
modifications and
adaptations thereof will be readily apparent to those skilled in the art
without departing from
the spirit and scope of the invention.
[0029] The invention described herein provides methods for protecting surfaces
of fluid
transport or process equipment. As used herein, the term "fluid processing or
transport
system, or a component thereof' means any equipment within which fluid (used
herein to
include any material that is wholly or partially in a gaseous or liquid state,
and includes,
without limitation, liquids, gases, two-phase systems, semi-solid system,
slurries, etc.) flows
or is stored, such as pipes, tubes, conduits, heat exchangers, beds, tanks,
reactors, nozzles,
cyclones, silencers, combustion chambers, intake manifolds, exhaust manifolds,
ports, etc., as
well as any equipment within which a chemical or physical change occurs,
wherein at least
one of the components participating in the chemical or physical change is a
fluid. Methods of
the invention protect surfaces of such equipment by inhibiting or preventing
degradation,
irrespective of whether the degradation occurs through deposition of material
on the surfaces,
through infiltration of material into the surfaces, or through corrosive
attack on the material
surface. The method is adapted to be used, in some embodiments, on fluid
process
equipment, or portions thereof, after assembly, resulting in significantly
decreased
interruption or interference with the protective functions of the coating by
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other structures within the equipment that are created when the equipment is
built or
assembled.
[0030] The present invention relates, in some aspects, to forming at least one
metal oxide on
an interior or exterior surface of fluid transport or process equipment. The
at least one metal
oxide can be formed on the surface by (1) placing at least one metal compound
on the surface
and (2) converting at least some of the at least one metal compound into at
least one metal
oxide. Metal compounds useful in the present invention contain at least one
metal atom and
at least one oxygen atom. Non-limiting examples of useful metal compounds
include metal
carboxylates, metal alkoxides, and metal (3-diketonates. Converting the metal
compound can
be accomplished by a wide variety of methods, such as, for example, heating
the environment
around the metal compound, heating the substrate under the metal compound,
heating the
metal compound itself, or a combination of those three. In other embodiments,
converting
the metal compound can be accomplished by catalysis.
[0031 ] Some embodiments of the present invention provide a method for forming
at least one
metal oxide on a surface of a fluid processing or transport system, or a
component thereof,
comprising: at least partially assembling the system; applying at least one
metal compound to
the surface; and exposing the surface with the applied at least one metal
compound to an
environment that will convert at least some of the compound to at least one
metal oxide. In
other embodiments, the fluid processing or transport system is substantially
assembled prior
to forming at least one metal oxide coating on at least one surface of the
system. In still other
embodiments, the fluid processing or transport system is fully assembled prior
to forming at
least one metal oxide coating on at least one surface of the system.
[0032] In some embodiments, the invention relates to a method for forming at
least one metal
oxide on a surface of a fluid processing or transport system, or a component
thereof,
comprising: applying a metal compound composition to the surface, wherein the
metal
compound composition comprises at least one metal salt of at least one
carboxylic acid; and
exposing the surface with the applied metal compound composition to an
environment that
will convert at least some of the salt to at least one metal oxide.
[0033] In some embodiments, the invention relates to a method for forming at
least one metal
oxide on a surface of a fluid processing or transport system, or a component
thereof,
comprising: applying a metal compound composition to the surface, wherein the
metal
compound composition comprises at least one metal alkoxide; and exposing the
surface with
the applied metal compound composition to an environment that will convert at
least some of
the metal alkoxide to at least one metal oxide.
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In some embodiments, the invention relates to a method for forming at least
one metal oxide
on a surface of a fluid processing or transport system, or a component
thereof, comprising:
applying a metal compound composition to the surface, wherein the metal
compound
composition comprises at least one metal (3-diketonate; and exposing the
surface with the
applied metal compound composition to an environment that will convert at
least some of the
metal (3-diketonate to at least one metal oxide.
[0034] In further embodiments, the invention relates to a method for forming
at least one
metal oxide on a surface of a fluid processing or transport system, or a
component thereof,
comprising: applying a metal compound composition to the surface, wherein the
metal
compound composition comprises at least one rare earth metal compound, and at
least one
transition metal compound; and exposing the surface with the applied metal
compound
composition to an environment that will convert at least some of the compounds
to at least
one metal oxide In some embodiments of methods of forming at least one metal
oxide on a
surface of a fluid processing or transport system, the at least one metal
oxide comprises a
metal oxide coating or metal oxide film. A metal oxide coating or a metal
oxide film, in
some embodiments, is crystalline, nanocrystalline, amorphous, thin film, or
diffuse, or a
combination of any of the foregoing. For example, a metal oxide coating in
some
embodiments of the present invention may comprise a film that contains both
nanocrystalline
and amorphous regions. In some embodiments, a metal oxide coating or metal
oxide film at
least partially diffuses or penetrates into surfaces of the fluid processing
or transport system
thereby precluding any intermediate bonding layers.
[0035] The invention, in additional embodiments, relates to a method for
forming at least one
metal oxide on a surface of a fluid processing or transport system, or a
component thereof,
comprising:
applying a liquid metal compound composition to the surface, wherein the
liquid
metal compound composition comprises a solution of at least one rare earth
metal
compound and at least one transition metal compound, in a solvent, and
exposing the surface with the applied liquid compound to a heated environment
that
will convert at least some of the metal compound to at least one metal oxide,
thereby
forming a metal oxide coating on the surface.
[0036] As provided herein, in some embodiments, the metal oxide coating may be
crystalline, nanocrystalline, amorphous, thin film, or diffuse, or a
combination of any of the
foregoing. For example, a metal oxide coating in some embodiments of the
present invention
may comprise a thin film that contains both nanocrystalline and amorphous
regions.
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[0037] In other embodiments, the invention relates to a method for forming an
oxidizing
coating on an interior surface of a fluid processing or transport system,
comprising:
applying a liquid metal carboxylate composition to the surface, wherein the
liquid metal
carboxylate composition comprises a solution of at least one rare earth metal
salt of a
carboxylic acid and at least one transition metal salt of a carboxylic acid,
in a solvent, and
exposing the surface with the applied liquid metal carboxylate composition to
a heated
environment that will convert at least some of the metal carboxylate to metal
oxides, thereby
forming a thin layer of a nanocrystalline coating on the surface.
[0038] In some embodiments, the invention relates to a method for forming an
oxidizing
coating on an interior surface of a fluid processing or transport system,
comprising:
applying a liquid metal carboxylate composition to the surface, wherein the
liquid
metal carboxylate composition comprises a solution of zirconium carboxylate
and at
least one transition metal salt of a carboxylic acid, in a solvent, and
exposing the surface with the applied liquid metal carboxylate composition to
a
heated environment that will convert at least some of the metal carboxylate to
metal
oxides, thereby forming a thin layer of a nanocrystalline coating on the
surface.
[0039] In additional embodiments, the method of the invention further includes
a step of
applying a solution of organosiloxane-silica in ethanol over the formed oxide
coating and
exposing the coated substrate to an environment that will remove volatile
components from
the solution without decomposing organo-silicon bonds. In some embodiments,
this step can
be repeated once or more.
[0040] The various coatings of the present invention are formed, in some
embodiments, by a
method of forming an oxidizing coating on a substrate comprising:
(a) applying a liquid metal compound composition to the substrate, wherein the
liquid
metal compound composition comprises a solution of at least one rare earth
metal compound
and at least one transition metal compound, in a solvent, and
(b) exposing the substrate with the applied liquid metal compound composition
to an
environment that will convert at least some of the metal compound to metal
oxides, thereby
forming an oxidizing coating on the substrate.
[0041 ] In other embodiments, the invention relates to metal oxide coatings
(and articles
coated therewith) containing two or more rare earth metal oxides and at least
one transition
metal oxide. Further embodiments of the invention relate to metal oxide
coatings (and
articles coated therewith), containing ceria, a second rare earth metal oxide,
and a transition
metal oxide. Some embodiments relate to metal oxide coatings (and articles
coated
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therewith), containing yttria, zirconia, and a second rare earth metal oxide.
In some cases, the
second rare earth metal oxide can include platinum or other known catalytic
elements.
[0042] In the case of catalytic surfaces, this method allows for cost savings
by reducing the
bulk amount of the catalyst. And, it also allows a wider variety of catalysts
to be applied
either as mixtures or in disparate layers to achieve tightly targeted results.
[0043] Therefore, some embodiments of the invention create a protective metal
oxide coating
on a chosen surface to serve as a prophylaxis against attack from chemical,
thermal, ionic, or
electronic degradation. The metal oxide coatings of some embodiments prevent
the growth
of fibers, formation of hydrate crystals, and act as a prophylaxis generally
against growth of
any materials that block, interfere, or contaminate the successful operation
of an enclosed
system.
[0044] Accordingly, some embodiments of the present invention provide a method
for
decreasing or preventing fouling of a surface of a fluid processing or
transport system, or a
component thereof, comprising applying at least one metal compound to the
surface, and
exposing the surface with the applied at least one metal compound to an
environment that
will convert at least some of the compound to at least one metal oxide,
wherein the at least
one metal oxide is resistant to fouling.
[0045] Other embodiments of the present invention provide a method for
decreasing or
preventing fouling of a surface of a sensor, or a component thereof,
comprising applying at
least one metal compound to the surface, and exposing the surface with the
applied at least
one metal compound to an environment that will convert at least some of the
compound to at
least one metal oxide, wherein the at least one metal oxide is resistant to
fouling.
[0046] Some embodiments of the present invention provide a method for reducing
or
preventing coke buildup on a surface of a fluid processing or transport
system, or a
component thereof, comprising applying at least one metal compound to the
surface, and
exposing the surface with the applied at least one metal compound to an
environment that
will convert at least some of the compound to at least one metal oxide,
wherein the at least
one metal oxide is resistant to coke buildup.
[0047] Other embodiments of the present invention provide a method for
reducing or
preventing corrosive attack on a surface of a fluid processing or transport
system, or a
component thereof, comprising applying at least one metal compound to the
surface, and
exposing the surface with the applied at least one metal compound to an
environment that
will convert at least some of the compound to at least one metal oxide,
wherein the at least
one metal oxide is resistant to corrosive attack.
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[0048] Still other embodiments provide methods for reducing or preventing
combustion
buildup on a flame-heated surface of a fluid processing or transport system,
or a component
thereof, comprising: applying at least one metal compound to the surface, and
exposing the
surface with the applied at least one metal compound to an environment that
will convert at
least some of the compound to at least one metal oxide, wherein the at least
one metal oxide
is resistant to combustion buildup.
[0049] Further embodiments provide methods for reducing or preventing fouling
of at least
one metal surface of a combustion engine system or a component thereof,
comprising
applying at least one metal compound to the surface, and exposing the surface
with the
applied at least one metal compound to an environment that will convert at
least some of the
compound to at least one metal oxide, wherein the at least one metal oxide is
resistant to
fouling.
[0050] In some embodiments, the at least one metal oxide is operable to render
a surface of a
fluid processing or transport system treated therewith resistant to
degradation or fouling for a
period of at least days or weeks. In another embodiment, the at least one
metal oxide is
operable to render a surface of a fluid processing or transport system treated
therewith
resistant to degradation or fouling for a period of at least months or years.
[0051 ]Some embodiments of the invention provide an improved corrosion-
resistant surface
treatment through the creation of a nanocrystalline grain structure of
zirconia- or cerium-
based materials, or surface treatments of other elemental compositions with
nanocrystalline
microstructures that serve to isolate the substrate from chemical, thermal, or
galvanic attack.
[0052] Additional embodiments provide a low cost means to form a useful
coating of
zirconia- or ceria-based ceramic material on a substrate, the coating having a
nanocrystalline
microstructure.
[0053] Some embodiments of the technology will prevent electrochemical
corrosion by
inhibiting the flow of electrons or ions into or from the substrate surface
and from or into the
process fluid stream.
[0054] Additional embodiments of the invention produce a dense metal oxide
coating that
does not suffer from cracking due to thermal stresses.
[0055] Some embodiments produce a metal oxide coating that does not suffer
from cracking
due to its fabrication method.
[0056] In further embodiments, the at least one metal oxide coating appears
uniform and
without cracks or holes from about 100x to about 1 000x magnification.
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[0057] Some embodiments provide a metal oxide coating comprising only one
metal oxide.
Other embodiments provide a metal oxide coating comprising only two metal
oxides. Still
other embodiments provide a metal oxide coating comprising only three metal
oxides. In yet
other embodiments, the metal oxide coating comprises four or more metal
oxides.
[0058] The present invention, in some cases, also provides a low cost method
for the creation
of a metal oxide coating that serves to protect a surface from chemical,
thermal, and/or
galvanic attack. The present invention also provides a means to diffuse chosen
surfaces with
selected chemical ingredients using a process that does not require damaging
high
temperature cycles, in several embodiments.
[0059] Yet other embodiments of this invention provide corrosion resistant
coatings of
organosiloxane-silica over metal oxide coating to impart prolonged usefulness
to substrates,
when such substrates have the tendency to corrode in aqueous environments with
or without
salts and other impurities dissolved in water.
[0060] Additional embodiments of the invention provide a means to form a metal
oxide
coating on the interior of a closed system after it is assembled, giving a
prophylactic coating
on all surfaces exposed to chosen process including welded areas, flanged
joints, etc. Further
embodiments provide a fluid processing or transport system comprising at least
one surface
comprising at least one metal oxide coating, in which the system has a large
size.
[0061 ] Some embodiments of the invention may be implemented such that the
metal oxide
coatings are formed on components of a fluid process system prior to its
assembly, for
example, to a pipe or heat exchanger at its place of original manufacture. In
this manner,
bulk coatings of metal oxides may be formed in a more automated fashion in
those
embodiments, thereby providing coverage over the majority of the interior of a
system while
still providing a reduced but chosen level of protection against surface
degradation, i.e.
leaving the in-field welded areas uncoated, which may be suitable for some
applications. In
other embodiments, only certain surfaces within a system may be coated for
desired
performance, whether it be for surface protection against degradation,
catalytic activity, or a
combination thereof.
[0062] Accordingly, further embodiments of the present invention provide
articles of
manufacture adaptable to provide a surface of a fluid processing or transport
system, or a
component thereof, wherein the surface comprises at least one metal oxide. In
some of those
embodiments, at least some of the at least one metal oxide is present as a
diffused coating.
[0063] Some embodiments of this invention provide a process for applying a
surface
treatment to an interior surface of an industrial process system or a
component thereof such
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that corrosion, erosion, or the building up of debris or a combination thereof
is satisfactorily
resisted by the surface treatment and the underlying surface, resulting in
improved
performance of the industrial fluid process system or component thereof.
[0064] Other embodiments of the invention provide a method of forming a metal
oxide
coating that is well-adhered to chosen interior surfaces of an industrial
process system.
[0065] Still other embodiments of the invention provide a method of forming a
metal oxide
coating on the interior of an enclosed piping system, wherein the coating has
a thickness of 5
microns or less.
[0066] Additional embodiments of the invention provide a means to economically
form a
metal oxide coating to chosen interior surfaces of an industrial process
system.
[0067] Yet other embodiments provide a method of forming a metal oxide coating
on at least
one component of an industrial process system prior to assembly.
[0068] Further embodiments provide a method of forming a metal oxide coating
on at least
one component of an industrial process system that has been in service,
wherein the inner
surfaces of the component, for example, a pipe or tube, have been cleaned
using any suitable
method of cleaning interior surfaces of industrial process system components
such as solvent
washing, blasting, pigging, etching, mechanical and/or chemical polishing,
spalling, steam
cleaning, and similar methods.
[0069] Still further embodiments of the invention provide a method of forming
a metal oxide
coating on at least one portion of an assembled industrial process system so
that the welded
areas, flanges, and assorted assembly points within the system receive the
coating.
[0070] Other additional embodiments provide a method of forming a metal oxide
coating on
at least one portion of an assembled industrial process system after all
assembly welding,
brazing, and similar joining processes are completed, when so desired, to
eliminate the
degradation that occurs when components with pre-existing coatings are joined
with high
temperature joining processes. For example, creating a welded joint on a pipe
with a
conventional surface treatment typically results in the degradation of the
conventional surface
treatment in zones adjoining the welded area, greatly reducing or eliminating
the
effectiveness of the conventional surface treatment.
[0071 ]Other embodiments of the invention provide a method of forming multiple
layers of at
least one metal oxide on at least one portion of an assembled industrial
process system.
[0072] Some embodiments of the present invention provide a method for forming
at least one
metal oxide on an interior surface of a fluid processing or transport system
or a component
thereof, comprising:
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placing at least one pig proximate to the interior surface;
applying at least one metal compound to the interior surface with the at least
one pig;
and
converting at least some of the at least one metal compound to at least one
metal
oxide.
[0073] In other embodiments, the process of placing, applying, and converting
can be
repeated, forming at least one metal oxide in more than one layer. In still
other embodiments,
various methods can be used to apply at least one metal compound to the
interior surface, in
addition to those methods employing at least one pig, again forming at least
one metal oxide
in more than one layer. Accordingly, in certain embodiments, this invention
relates to
processes of applying a chosen composition to chosen surfaces of an industrial
process
system, then utilizing a conversion method to convert the formulation to a
useful surface
coating.
[0074] In some embodiments of methods of the present invention, at least one
metal oxide or
metal oxide coating is formed in an inert environment, including an
environment wherein no
or substantially no oxygen is present. In other embodiments, at least one
metal oxide or
metal oxide coating is formed in an aerobic environment.
[0075] Industrial fluid processing and/or transport systems operable to be
treated with metal
oxides including metal oxide coatings, according to some embodiments of the
invention,
include without limitation petroleum refineries, petrochemical processing
plants, petroleum
transport and storage facilities such as pipelines, oil tankers, fuel
transport vehicles, and gas
station fuel tanks and pumps, sensors, industrial chemical manufacturing
plants, aeronautical
and aerospace fluid storage and transport systems including fuel systems and
hydraulic
systems, food and dairy processing systems, combustion engines, turbine
engines, and rocket
engines.
BRIEF DESCRIPTION OF THE DRAWINGS
[0076] Further aspects, features and advantages of the present invention will
become
apparent from the drawings and detailed description of the embodiments that
follow.
[0077] Figure 1, adapted from Figure 6 of U.S. Patent No. 5,230,842, shows a
pig assembly
useful in some embodiments of the present invention for depositing at least
one metal
compound on the interior surfaces of a fluid processing or transport system.
[0078] Figure 2 shows a photograph of a cross section of an untreated pipe
revealing
crystalline growth that restricts flow through the pipe.
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[0079] Figure 3 shows a photograph of an uncoated steel coupon after a one
hour exposure to
Aqua Regia.
[0080] Figure 4 shows a photograph of a steel coupon coated with "Zircon"
after one hour
exposed to Aqua Regia.
[0081]Figure 5 shows a photograph of a steel coupon coated with "Glass" after
one hour
exposed to Aqua Regia.
[0082] Figure 6 shows a photograph of a steel coupon coated with "YSZ" after
one hour
exposed to Aqua Regia.
[0083] Figure 7 shows a photograph of a steel coupon coated with "Clay" after
one hour
exposed to Aqua Regia.
[0084] Figure 8 shows TEM micrograph at approximately two million x
magnification of a
steel substrate having a Y/Zr oxide coating in cross-section.
DETAILED DESCRIPTION
[0085] As used herein, the term "rare earth metal" includes those metals in
the lanthanide
series of the Periodic Table, including lanthanum. The term "transition metal"
includes
metals in Groups 3-12 of the Periodic Table (but excludes rare earth metals).
The term "metal
oxide" particularly as used in conjunction with the above terms includes any
oxide that can
form or be prepared from the metal, irrespective of whether it is naturally
occurring or not.
The "metal" atoms of the metal oxides of the present invention are not
necessarily limited to
those elements that readily form metallic phases in the pure form. "Metal
compounds"
include substances such as molecules comprising at least one metal atom and at
least one
oxygen atom. Metal compounds can be converted into metal oxides by exposure to
a suitable
environment for a suitable amount of time.
[0086] As used herein, the term "phase deposition" includes any coating
process onto a
substrate that is subsequently followed by the exposure of the substrate
and/or the coating
material to an environment that causes a phase change in either the coating
material, one or
more components of the coating material, or of the substrate itself. A phase
change may be a
physical phase change, such as for example, a change from fluid to solid, or
from one crystal
phase to another, or from amorphous to crystalline or vice versa. "Adaptable
to provide"
indicates the ability to make available. For example, an "article adaptable to
provide a
surface in a fluid processing or transport system" is an article, such as a
pipe, that has a
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surface that is or can be assembled into such a system by using manufacturing,
construction,
and/or assembly steps.
[0087] In some embodiments of the invention, a device commonly known as a
"pig" is used.
A pig comprises any suitable features and characteristics. A pig comprises a
body, and
optionally one or more brushes, spray nozzles, absorbent structures such as
polymer foams
and sponges, stabilizers, hydraulic cups, hydraulically-driven wheels and/or
tracks,
mechanically-driven wheels and/or tracks, conversion devices such as IR
emitters, and the
like. In some embodiments, the pig can act to distribute the at least one
metal compound
onto the surface to be treated. In other embodiments, the pig acts as a mobile
plug,
containing a volume of the at least one metal compound, thereby distributing
it to the surface.
In still other embodiments, the pig acts as a mobile converter, causing at
least some of the at
least one metal compound to convert to at least one metal oxide.
[0088] In certain embodiments, a pig is or comprises a sponge. Suitable
sponges include, but
are not limited to, open cell foams, closed cell foams, sponges having a
diameter greater than
the interior diameter of a pipe to be treated, and sponges comprising
polyurethane, polyester,
polyethylene, polyvinyl alcohol, cellulose, natural sponge, and combinations
thereof. It is
customary to use pigs that are fairly dense and relatively uncompressible, and
having a
diameter that is perhaps five percent larger than the interior diameter of a
pipe to be treated
with the pig. However, if that pig is damaged during its passage through a
pipe, the pig could
loose its ability to form a seal sufficient to allow the pig to be pushed
through the pipe.
Applicants have unexpectedly found that using a highly compressible sponge as
the pig
affords numerous advantages over less-compressible pigs. Some of those
advantages, one or
more of which might be present in a given embodiment of the present invention,
include:
= Highly compressible sponges are better able to maneuver through "mule ears,"
which
are 90 degree intersections of one pipe entering another, and other difficult
pipe
geometries such as elbows and U-bends. In some cases, a compressible sponge
can
navigate a U-bend that appears very close to the pig launching flange, whereas
a rigid
pig cannot build the momentum necessary to get past the U-bend. Rigid pigs
frequently get stuck and destroyed navigating difficult pipe geometries.
= Highly compressible sponges can treat pipes having different internal
diameters. A
less-compressible pig passing from a narrower diameter to a larger diameter
might
loose its ability to form a seal, and may become stuck in the wider portion of
the pipe.
A highly compressible sponge having substantial "deflection" or resiliency,
can
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expand to fully contact and treat the entire inner surface of the wider
portion of the
pipe, and is less likely to loose its seal.
= A highly compressible sponge, such as an open cell foam sponge, can absorb a
treating liquid, and then apply that liquid to the inner surface of a pipe. On
the other
hand, a non-compressible pig requires a quantity of treating liquid to be
placed in the
pipe before the pig. That can be messy, or it can require more than one pig to
contain
the treating liquid.
= A sponge need not have a particular shape, whereas a pig is usually
manufactured to
have a certain shape to travel through a pipe. This advantage allows costs
savings, in
addition to the greater maneuverability mentioned above.
[0089] In additional embodiments, a pigging package comprising a first pig and
a second pig,
and a quantity of coating liquid that comprises at least one metal compound.
Further
embodiments comprise one or more additional pigs or other components
positioned between
the first pig and the second pig. In some embodiments, the first pig acts as a
sealing element
within a pipe or tube and a second pig is positioned within a chosen section
of a pipe at a
distance rearward of the first pig such that a volume is defined by the aft
section of the first
pig, the inner walls of the pipe, and the front segment of the second pig.
This defined volume
may be filled with the coating liquid and the second pig constructed such that
as the pair of
pigs is transported through the pipe, a thin film of liquid is allowed to leak
past the trailing
(second) pig and thus the liquid becomes distributed on the inner surface of
the pipe.
[0090] In some implementations of the invention the trailing pig may be
constructed with an
outer surface being comprised of an absorbent material, for example, urethane
foam, such
that the trailing (second) pig serves as a swab that applies the liquid to the
inner surface of the
pipes inner walls. In this implementation of the invention the volume of
liquid that resides
between the first pig and the second pig serves as a reservoir to keep the
trailing pig saturated
with the liquid formulation such that the wetting of the inner surface of the
pipe's inner walls
is accomplished in a continual fashion for a chosen length within the pipe.
[0091 ] In some embodiments of the invention, the motive force for the
movement of the
pigging package may be provided by air or other gas pressure provided behind
the trailing
pig, taking advantage of the fact that the coating liquid residing between the
two pigs is an
incompressible liquid and thus the gas pressure acting upon the trailing
(second) pig will be
transferred to the leading (first) pig and, provided that the gas pressure
ahead of the leading
(first) pig is sufficiently lower than the gas pressure pressing on the
backside of the trailing
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(second) pig, movement will occur as the pigging package moves toward the zone
within the
pipe with lower gas pressure. In some embodiments, the gas pressure pressing
against the
trailing pig may need to be greater than the gas pressure ahead of the leading
pig by a value
of up to 600 psi in some cases to promote movement of the pigging package. In
other
embodiments, gas pressure may be supplied using any suitable methods, such as,
for
example, one or more of compressors, fans, pumps, chemical reactions,
combustion, and the
like.
[0092] In other embodiments of the invention, the motive force for the pigging
package may
be provided by compressed inert gas or gaseous mixture such that the wetted
inner surfaces
of the piping system are at least partially prevented from oxidizing once
wetted with the
coating liquid. In some embodiments, the inert gas or gaseous mixture may be
heated to a
chosen temperature sufficient to convert at least a portion of the coating
liquid wetting the
pipe's inner surfaces into a metal oxide coating.
[0093] In other embodiments of the invention an inert gas may be fed into the
piping system
after it has been wetted with the coating liquid but prior to heating of even
a portion of the
pipe walls. The inert gas, in some embodiments, controls oxidation of the
wetted pipe
surfaces as their temperature is increased.
[0094] In other embodiments of the invention, the motive force for the pigging
package may
be provided by hydraulic pressure provided to the rearmost sections of the
trailing pig, said
hydraulic pressure being sufficiently higher than the pressure, whether gas or
hydraulic, that
exists ahead of the leading pig, and thus promoting the desired motion in the
pigging
package. In still other embodiments, the frictional forces that exist between
the pigs and the
inner walls of the pipe will determine the amount of pressure, either gaseous
or hydraulic,
that will be needed to move the pigging package through the pipe at the
desired rate.
[0095] In some embodiments of the invention, a spray head may be provided in
one or both
of the pigs through which the coating material may be applied to the inner
surface of the pipe.
In some iterations of this embodiment, the pressure required to discharge the
coating material
may be provided by a pressure container provided in the pigging package as
taught in U.S.
Patent No. 4,774,905, which is incorporated by reference in its entirety.
[0096] In other embodiments, the pressure required to discharge the coating
material may be
provided by the motive pressure, whether hydraulic or gaseous, that may be
used to push the
pigging package through the piping system. In these embodiments, the motive
pressure that is
acting upon the trailing pig will be physically transferred by default to the
coating material
residing between the two pigging elements, thus pressurizing the liquid
coating material
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within this defined reservoir. This pressure may be used to force the liquid
coating material
through one or more spray nozzles to apply the coating material to the inner
surfaces of the
pipe. In some embodiments where the motive pressure is greater than needed for
efficient
spraying of the liquid coating material, a known pressure regulator may be
provided between
the pressurized coating material reservoir and the spray head(s) that limits
the liquid feed
pressure to the spray head to a desired level, for example, 100 psi.
[0097] In some embodiments, the liquid coating material may be provided by a
feed line
connected to one of the pigging elements such that one or both pigging
elements remain
saturated with the liquid coating material and a desired amount of liquid is
dispersed onto the
inner surface of the pipe. In this iteration, the feed line may have guide
discs provided along
its length to prevent the line from touching the inner surfaces of the pipe
and thus restricting
the line's movement.
[0098] In other embodiments, the liquid coating material may be provided by a
feed line
connected to one of the pigging elements such that at least one spray nozzle
provided with the
pig assembly may receive a sufficient supply of the coating liquid to disperse
a desired
amount of liquid onto the chosen surfaces of the pipe.
[0099] In still other embodiments, the pressurized liquid coating material may
be provided by
a feed line connected to at least one pig provided with a spray nozzle for the
application of
the liquid coating material to chosen surfaces of an industrial process system
wherein the
motive force for movement of the pigging device is provided by a hydraulic
actuator motor
driving traction devices such as wheels, said actuator capturing a portion of
the feed line
liquid pressure prior to the coating material being sprayed from the provided
spray nozzle,
said hydraulic pressure being provided upstream at the head of the feed line
via known means
such as pumps, compressors, or similar. In some embodiments, the pressure that
is used to
feed the spray nozzle is interrupted prior to being ejected from the nozzle
and its pressure
energy is used to drive the pig forward using wheels driven by a hydraulic
motor.
[00100] In some embodiments of the invention, a single pig may be pulled
through a
pipe by a feed line that transfers sufficient liquid coating material to the
pig such that the
pig's absorbent material remains saturated to a level that leaves a well-
wetted surface on the
inside of the pipe, said feed line also being sufficiently strong to provide
the necessary
pulling force to move the pig through the pipe or piping system.
[00101] In still other embodiments of the invention, a single pig may be
pulled through
a pipe by a feed line that transfers sufficient liquid coating material to the
pig and feeds a
spray device provided in the pig that atomizes the liquid coating material and
directs it to the
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inside of the pipe, said feed line also being sufficiently strong to provide
the necessary
pulling force to move the pig through the pipe or piping system.
[00102] In some embodiments of the invention, guides may be provided at chosen
points along the feed tube to keep the feed tube centered within the cross
sectional plane of
the pipe. In some iterations of this embodiment the guides that center the
feed tube may be
constructed using known spring steel guides, rigid discs, or other means known
to those
skilled in the art.
[00103] In some embodiments of the invention the liquid coating comprising at
least
one metal compound may be applied to the inner surface of a pipe and then
exposing the
wetted surface to an environment that will convert at least some of the
compound to at least
one metal oxide, for example, through the elevation of the temperature of the
wetted surface
to a desired temperature through known means.
[00104] The term alkyl, as used herein, refers to a saturated straight,
branched, or
cyclic hydrocarbon, or a combination thereof, including C1 to C24, methyl,
ethyl, n-propyl,
isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, cyclopentyl, isopentyl,
neopentyl, n-hexyl,
isohexyl, cyclohexyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl,
heptyl, octyl,
nonyl, and decyl.
[00105] The term alkoxy, as used herein, refers to a saturated straight,
branched, or
cyclic hydrocarbon, or a combination thereof, including C1 to C24, methyl,
ethyl, n-propyl,
isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, cyclopentyl, isopentyl,
neopentyl, n-hexyl,
isohexyl, cyclohexyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl,
heptyl, octyl,
nonyl, and decyl, in which the hydrocarbon contains a single-bonded oxygen
atom that can
bond to or is bonded to another atom or molecule.
[00106] The terms alkenyl and alkynyl, as used herein, refer to straight,
branched, or
cyclic hydrocarbon with at least one double or triple bond, respectively.
Alkenyl and alkynyl
include, but are not limited to, C1 to C24 hydrocarbons.
[00107] The term aryl or aromatic, as used herein, refers to monocyclic or
bicyclic
hydrocarbon ring molecule having conjugated double bonds about the ring. In
some
embodiments, the ring molecule has 5- to 12-members, but is not limited
thereto. The ring
may be unsubstituted or substituted having one or more alike or different
independently-
chosen substituents, wherein the substituents are chosen from alkyl, alkenyl,
alkynyl, alkoxy,
hydroxyl, and amino radicals, and halogen atoms. Aryl includes, for example,
unsubstituted
or substituted phenyl and unsubstituted or substituted naphthyl.
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[00108] The term heteroaryl as used herein refers to a monocyclic or bicyclic
aromatic
hydrocarbon ring molecule having at least one heteroatom chosen from 0, N, P,
and S as a
member of the ring, and the ring is unsubstituted or substituted with one or
more alike or
different substituents independently chosen from alkyl, alkenyl, alkynyl,
hydroxyl, alkoxy,
amino, alkylamino, dialkylamino, thiol, alkylthio, =O, =NH, =PH, =S, and
halogen atoms. In
some embodiments, the ring molecule has 5- to 12-members, but is not limited
thereto.
[00109] The term hydrocarbon refers to molecules that contain carbon and
hydrogen.
[00110] "Alike or different," when describing three or more substituents for
example,
indicates combinations in which (a) all substituents are alike, (b) all
substituents are different,
and (c) some substituents are alike but different from other substituents.
[00111] Suitable metal compounds that form metal oxides include substances
such as
molecules containing at least one metal atom and at least one oxygen atom. In
some
embodiments, metal compounds that form metal oxides include metal
carboxylates, metal
alkoxides, and metal (3-diketonates.
A. METAL CARBOXYLATES
[00112] The metal salts of carboxylic acids useful in the present invention
can be made
from any suitable carboxylic acids according to methods known in the art. For
example, U.S.
Patent No. 5,952,769 to Budaragin discloses suitable carboxylic acids and
methods of making
metal salts of carboxylic acids, among other places, at columns 5-6. The
disclosure of U.S.
Patent No. 5,952,769 is incorporated herein by reference. In some embodiments,
the metal
carboxylate can be chosen from metal salts of 2-hexanoic acid. Moreover,
suitable metal
carboxylates can be purchased from chemical supply companies. For example,
cerium(III) 2-
ethylhexanoate, magnesium(II) stearate, manganese(II) cyclohexanebutyrate, and
zinc(II)
methacrylate are available from Sigma-Aldrich of St. Louis, MO. See Aldrich
Catalogue,
2005-2006. Additional metal carboxylates are available from, for example, Alfa-
Aesar of
Ward Hill, MA.
[00113] The metal carboxylate composition, in some embodiments of the present
invention, comprises one or more metal salts of one or more carboxylic acids
("metal
carboxylate"). Metal carboxylates suitable for use in the present invention
include at least
one metal atom and at least one carboxylate radical -OC(O)R bonded to the at
least one metal
atom. As stated above, metal carboxylates can be produced by a variety of
methods known to
one skilled in the art. Non-limiting examples of methods for producing the
metal carboxylate
are shown in the following reaction schemes:
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nRCOOH + Me - (RCOO)õMeõ+ + 0.5nH2 (for alkaline earth metals, alkali metals,
and thallium).
nRCOOH + Me"+(OH),, (RCOO)õMen+ + nH20 (for practically all metals having
a solid hydroxide).
nRCOOH + Me "+(C03)0.5,, -* (RCOO)õMen+ + 0.5nH20 + 0.5nCO2 (for alkaline
earth metals, alkali metals, and thallium).
nRCOOH + Me"+(X)n/m -* (RCOO)õMen+ + n/mHmX (liquid extraction, usable for
practically all metals having solid salts).
In the foregoing reaction schemes, X is an anion having a negative charge m,
such as,
e.g., halide anion, sulfate anion, carbonate anion, phosphate anion, among
others; n is a
positive integer; and Me represents a metal atom.
[00114] R in the foregoing reaction schemes can be chosen from a wide variety
of
radicals. Suitable carboxylic acids for use in making metal carboxylates
include, for
example:
Monocarboxylic acids:
[00115] Monocarboxylic acids where R is hydrogen or unbranched hydrocarbon
radical, such as, for example, HCOOH - formic, CH3COOH - acetic, CH3CH2COOH -
propionic, CH3CH2CH2OOOH (C4H802)- butyric, C5H1002 - valeric, C6H1202 -
caproic,
C7H14 - enanthic; further: caprylic, pelargonic, undecanoic, dodecanoic,
tridecylic, myristic,
pentadecylic, palmitic, margaric, stearic, and nonadecylic acids;
[00116] Monocarboxylic acids where R is a branched hydrocarbon radical, such
as, for
example, (CH3)2CHCOOH - isobutyric, (CH3) 2CHCH2COOH - 3-methylbutanoic,
(CH3)3CCOOH - trimethylacetic, including VERSATIC 10 (trade name) which is a
mixture
of synthetic, saturated carboxylic acid isomers, derived from a highly-
branched C10 structure;
[00117] Monocarboxylic acids in which R is a branched or unbranched
hydrocarbon
radical containing one or more double bonds, such as, for example, CH2=CHCOOH -
acrylic,
CH3CH=CHCOOH - crotonic, CH3(CH2)7CH=CH(CH2)7000H - oleic,
CH3CH=CHCH=CHCOOH - hexa-2,4-dienoic, (CH3)2C=CHCH2CH2C(CH3)=CHCOOH -
3,7-dimethylocta-2,6-dienoic, CH3(CH2)4CH=CHCH2CH=CH(CH2)7000H - linoleic,
further: angelic, tiglic, and elaidic acids;
[00118] Monocarboxylic acids in which R is a branched or unbranched
hydrocarbon
radical containing one or more triple bonds, such as, for example, CH=000OH -
propiolic,
CH3C=000OH - tetrolic, CH3(CH2)4C=CCOOH - oct-2-ynoic, and stearolic acids;
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[00119] Monocarboxylic acids in which R is a branched or unbranched
hydrocarbon
radical containing one or more double bonds and one or more triple bonds;
[00120] Monocarboxylic acids in which R is a branched or unbranched
hydrocarbon
radical containing one or more double bonds and one or more triple bonds and
one or more
aryl groups;
[00121] Monohydroxymonocarboxylic acids in which R is a branched or unbranched
hydrocarbon radical that contains one hydroxyl substituent, such as, for
example,
HOCH2COOH - glycolic, CH3CHOHCOOH - lactic, C6H5CHOH000H - amygdalic, and
2-hydroxybutyric acids;
[00122] Dihydroxymonocarboxylic acids in which R is a branched or unbranched
hydrocarbon radical that contains two hydroxyl substituents, such as, for
example,
(HO)2CH000H - 2,2-dihydroxyacetic acid;
[00123] Dioxycarboxylic acids, in which R is a branched or unbranched
hydrocarbon
radical that contains two oxygen atoms each bonded to two adjacent carbon
atoms, such as,
for example, C6H3(OH)2COOH - dihydroxy benzoic, C6H2(CH3)(OH)2COOH -
orsellinic;
further: caffeic, and piperic acids;
[00124] Aldehyde-carboxylic acids in which R is a branched or unbranched
hydrocarbon radical that contains one aldehyde group, such as, for example,
CHOCOOH -
glyoxalic acid;
[00125] Keto-carboxylic acids in which R is a branched or unbranched
hydrocarbon
radical that contains one ketone group, such as, for example, CH3COCOOH -
pyruvic,
CH3COCH2COOH - acetoacetic, and CH3COCH2CH2COOH - levulinic acids;
[00126] Monoaromatic carboxylic acids, in which R is a branched or unbranched
hydrocarbon radical that contains one aryl substituent, such as, for example,
C6H5000H -
benzoic, C6H5CH2OOOH - phenylacetic, C6H5CH(CH3)COOH -
2-phenylpropanoic, C6H5CH=CHCOOH - 3-phenylacrylic, and C6H5C=CCOOH - 3-phenyl-
propiolic acids;
Multicarboxylic acids:
[00127] Saturated dicarboxylic acids, in which R is a branched or unbranched
saturated
hydrocarbon radical that contains one carboxylic acid group, such as, for
example, HOOC-
COOH - oxalic, HOOC-CH2-COOH - malonic,
HOOC-(CH2)2-COOH - succinic, HOOC-(CH2)3-COOH - glutaric,
HOOC-(CH2)4-COOH - adipic; further: pimelic, suberic, azelaic, and sebacic
acids;
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[00128] Unsaturated dicarboxylic acids, in which R is a branched or unbranched
hydrocarbon radical that contains one carboxylic acid group and at least one
carbon-carbon
multiple bond, such as, for example, HOOC-CH=CH-COOH - fumaric; further:
maleic,
citraconic, mesaconic, and itaconic acids;
[00129] Polybasic aromatic carboxylic acids, in which R is a branched or
unbranched
hydrocarbon radical that contains at least one aryl group and at least one
carboxylic acid
group, such as, for example, C6H4(COOH)2 - phthalic (isophthalic,
terephthalic), and
C6H3(COOH)3 - benzyl-tri-carboxylic acids;
[00130] Polybasic saturated carboxylic acids, in which R is a branched or
unbranched
hydrocarbon radical that contains at least one carboxylic acid group, such as,
for example,
ethylene diamine N,N'-diacetic acid, and ethylene diamine tetraacetic acid
(EDTA);
Polybasic oxyacids:
[00131] Polybasic oxyacids, in which R is a branched or unbranched hydrocarbon
radical containing at least one hydroxyl substituent and at least one
carboxylic acid group,
such as, for example, HOOC-CHOH-COOH - tartronic,
HOOC-CHOH-CH2-COOH - malic, HOOC-C(OH)=CH-COOH - oxaloacetic, HOOC-
CHOH-CHOH-COOH - tartaric, and
HOOC-CH2-C(OH) COOH-CH2COOH - citric acids.
[00132] In some embodiments, the monocarboxylic acid comprises one or more
carboxylic acids having the formula I below:
R --C(R")(R')--COOH (I)
wherein:
R is selected from H or C1 to C24 alkyl groups; and
R' and R" are each independently selected from H and CI to C24 alkyl groups;
wherein the alkyl groups of R , R', and R" are optionally and independently
substituted with
one or more substituents, which are alike or different, chosen from hydroxy,
alkoxy, amino,
and aryl radicals, and halogen atoms.
[00133] Some suitable alpha branched carboxylic acids typically have an
average
molecular weight in the range 130 to 420. In some embodiments, the carboxylic
acids have
an average molecular weight in the range 220 to 270. The carboxylic acid may
also be a
mixture of tertiary and quaternary carboxylic acids of formula I. VIK acids
can be used as
well. See U.S. Patent No. 5,952,769, at col. 6,11. 12-51.
[00134] Either a single carboxylic acid or a mixture of carboxylic acids can
be used to
form the metal carboxylate composition. In some embodiments, a mixture of
carboxylic
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acids is used. In still other embodiments, the mixture contains 2-
ethylhexanoic acid where R
is H, R" is C2H5 and R' is C4H9 in formula (I) above. In some embodiments,
this acid is the
lowest boiling acid constituent in the mixture. When a mixture of metal
carboxylates is used,
the mixture has a broader evaporation temperature range, making it more likely
that the
evaporation temperature of the mixture will overlap the metal carboxylate
decomposition
temperature, allowing the formation of a solid metal oxide coating. Moreover,
the possibility
of using a mixture of carboxylates avoids the need and expense of purifying an
individual
carboxylic acid.
[00135] For those embodiments of the present invention that involve a cleaning
composition that comprises one or more carboxylic acids, any of the
aforementioned
carboxylic acids may be suitable, alone or in combination.
B. METAL ALKOXIDES
[00136] Metal alkoxides suitable for use in the present invention include at
least one
metal atom and at least one alkoxide radical -OR2 bonded to the at least one
metal atom.
Such metal alkoxides include those of formula II:
M(OR2)Z (II)
in which M is a metal atom of valence z+;
z is a positive integer, such as, for example, 1, 2, 3, 4, 5, 6, 7, and 8;
R2 can be alike or different and are independently chosen from unsubstituted
and
substituted alkyl, unsubstituted and substituted alkenyl, unsubstituted and
substituted
alkynyl, unsubstituted and substituted heteroaryl, and unsubstituted and
substituted
aryl radicals,
wherein substituted alkyl, alkenyl, alkynyl, heteroaryl, and aryl radicals are
substituted with one or more alike or different substituents independently
chosen from
halogen, hydroxy, alkoxy, amino, heteroaryl, and aryl radicals.
In some embodiments, z is chosen from 2, 3, and 4.
[00137] Metal alkoxides are available from Alfa-Aesar and Gelest, Inc., of
Morrisville,
PA. Lanthanoid alkoxides such as those of Ce, Nd, Eu, Dy, and Er are sold by
Kojundo
Chemical Co., Saitama, Japan, as well as alkoxides of Al, Zr, and Hf, among
others. See,
e.g., http://www.kojundo.co.jp/English/Guide/material/lanthagen.html.
[00138] Examples of metal alkoxides useful in embodiments of the present
invention
include methoxides, ethoxides, propoxides, isopropoxides, and butoxides and
isomers
thereof. The alkoxide substituents on a give metal atom are the same or
different. Thus, for
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example, metal dimethoxide diethoxide, metal methoxide diisopropoxide t-
butoxide, and
similar metal alkoxides can be used. Suitable alkoxide substituents also may
be chosen from:
1. Aliphatic series alcohols from methyl to dodecyl including branched and
isostructured.
2. Aromatic series alcohols: benzyl alcohol - C6H5CH2OH; phenyl-ethyl alcohol -
C8H10O; phenyl- propyl alcohol - C9H120, and so on.
[00139] Metal alkoxides useful in the present invention can be made according
to
many methods known in the art. One method includes converting the metal halide
to the
metal alkoxide in the presence of the alcohol and its corresponding base. For
example:
MXZ + zHOR2 -* M(OR2)Z + zHX
in which M, R2, and z are as defined above for formula II, and X is a halide
anion.
C. METAL (3-DIKETONATES
[00140] Metal (3-diketonates suitable for use in the present invention contain
at least
one metal atom and at least one J3-diketone of formula III as a ligand:
R3 R6 (III )
R4 R5
in which
R3, R4, R5, and R6 are alike or different, and are independently chosen from
hydrogen,
unsubstituted and substituted alkyl, unsubstituted and substituted alkoxy,
unsubstituted and substituted alkenyl, unsubstituted and substituted alkynyl,
unsubstituted and substituted heteroaryl, unsubstituted and substituted aryl,
carboxylic
acid groups, ester groups having unsubstituted and substituted alkyl, and
combinations thereof,
wherein substituted alkyl, alkoxy, alkenyl, alkynyl, heteroaryl, and aryl
radicals are
substituted with one or more alike or different substituents independently
chosen from
halogen atoms, hydroxy, alkoxy, amino, heteroaryl, and aryl radicals.
[00141] It is understood that the (3-diketone of formula III may assume
different
isomeric and electronic configurations before and while chelated to the metal
atom. For
example, the free (3-diketone may exhibit enolate isomerism. Also, the (3-
diketone may not
retain strict carbon-oxygen double bonds when the molecule is bound to the
metal atom.
[00142] Examples of (3-diketones useful in embodiments of the present
invention
include acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone,
2,2,6,6-tetramethyl-
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3,5-heptanedione, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione,
ethyl acetoacetate,
2-methoxyethyl acetoacetate, benzoyltrifluoroacetone,
pivaloyltrifluoroacetone, benzoyl-
pyruvic acid, and methyl-2,4-dioxo-4-phenylbutanoate.
[00143] Other ligands are possible on the metal (3-diketonates useful in the
present
invention, such as, for example, alkoxides such as -OR2 as defined above, and
dienyl radicals
such as, for example, 1,5-cyclooctadiene and norbornadiene.
[00144] Metal (3-diketonates useful in the present invention can be made
according to
any method known in the art. 0-diketones are well known as chelating agents
for metals,
facilitating synthesis of the diketonate from readily available metal salts.
[00145] Metal (3-diketonates are available from Alfa-Aesar and Gelest, Inc.
Also,
Strem Chemicals, Inc. of Newburyport, MA, sells a wide variety of metal (3-
diketonates on
the internet at http://www.strem.com/code/template.ghc?direct=cvdindex.
[00146] In some embodiments of the invention, ports may be provided within the
exterior surfaces of an enclosed component of an industrial system, for
example, in the wall
of a pipe, said ports providing a means for delivery of a liquid wherein the
pressure within the
pipe to be coated is lowered to a sufficient level to produce at least partial
vaporization of the
liquid as it is delivered to the interior portions of the pipe, such that the
vaporized portion of
the liquid then condenses on the inner surfaces of the pipe and provides a
well-wetted
surface. In some embodiments, multiple delivery ports for delivering the
liquid coating
material into the low pressure interior of a pipe may be provided along a
length of pipe, for
example, and a chosen fluid delivered to each port via known manifolds,
piping, or other
fluid transfer means such that sufficient liquid material is delivered to the
interior of the pipe
and partially or fully vaporized wherein the condensation of the coating
material vapors onto
the inner surfaces of the pipe to establish a desired coating on the interior
surfaces of the pipe.
In some iterations of this embodiment, existing holes provided within a system
for
thermocouple placement may be used, temporarily or permanently, as
introduction ports
through which a coating material may be introduced to the interior of a sealed
system, said
coating material subsequently being at least partially vaporized via a
reduction in pressure
within the sealed system.
[00147] In some embodiments of the invention, wetting of the inner surfaces of
the
pipe is followed by a curing phase wherein heat is provided to the surfaces
using suitable
methods to achieve the conversion of at least a portion of the delivered
liquid into a metal
oxide coating. As described herein, suitable methods for converting at least a
portion of the
at least one metal compound into at least one metal oxide include, but are not
limited to,
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flushing the wetted system or component thereof with high-temperature gas;
induction
heating of the walls of the system or component; heating with one or more
lasers, microwave
emitters, infrared emitters, or plasma; flaming, for example of the outside
walls of the system
or component, exposing the wetted system or component to the thermal energy of
one or
more exothermic reactions, and combinations thereof.
[00148] In some embodiments of the invention, a flexible feed tube may be
provided
along the inside of a pipe wherein the feed tube has small holes provided
within its exterior
leading to its interior such that when the pressure within the tube is higher
than the pressure
outside of the tube, fluid or gases within the tube are caused to move from
within the feed
tube to the interstitial space between the tube's outer surface and the pipe's
inner surface such
that at least a portion of the fluid condenses onto the inner surface of the
pipe. In some
embodiments of the invention the pressure within the interstitial space
between the flexible
tube and the inner wall of the pipe may be provided with a sufficient vacuum
level such that
any liquid within the flexible tube will be drawn into the interstitial space
and subsequently
deposit on the inner surfaces of the pipe. At least a portion of this fluid
that leaves the flexible
tube will attach itself to the inner surface of the pipe and can thus be
converted to a metal
oxide coating through some secondary process such as drying in dehydrated air,
heating the
wetted surfaces to a chosen temperature, exposing the liquid coating to
ultraviolet light, etc.
[00149] . In some embodiments of the invention, a coating may be formed on the
inside
of a pipe or passageway through the use of a spray nozzle fed by a flexible
hose. For
example, a composition comprising at least one metal compound is supplied at
sufficient
pressure to achieve a uniform application of the composition on the inner
surfaces of the
passageway, such as by dispersion through one or more spray nozzles affixed to
at least one
pig. Then, the at least one metal compound may be converted to a coating on
the inner
surfaces of the passageway through a heating process provided by an infrared
emitter that is
placed into the passageway proximate to the wetted area.
[00150] In some embodiments, at least one IR emitter is mounted to a pig that
also
supports a spray nozzle and a means to keep the spray nozzle and IR emitter
centered within
the passageway. Such means comprises, in some embodiments, guides such as
flexible
fingers or other suitable structures for centering devices within passageways,
such as those
familiar to persons skilled in the art.
[00151] In some implementations, such guides ride against the inner walls of
the
passageway "upstream" of the spray nozzle such that the guides' contact with
the
passageway's inner walls do not wipe the composition off of the inner surface
of the pipe.
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[00152] In some implementations, the at least one IR emitter is located
downstream of
the spray nozzle such that the spray droplets of the composition are fully
dispersed and in
contact with the passageway's inner wall prior to the IR emitter's
electromagnetic radiation
being proximate to the surface and thus providing a means to reduce the amount
of airborne
spray that might contact the IR emitter itself. In some embodiments, the at
least one IR
emitter is located on the same pig as one or more spray nozzles. In other
embodiments, the at
least one IR emitter is located on a pig other than the pig comprising one or
more spray
nozzles.
[00153] In some embodiments a feed of an inert gas may be provided to create a
non-
oxidizing atmosphere for the heating process of the conversion liquid and the
material
underneath such that oxidation of the inner wall of the passageway is reduced
or eliminated.
[00154] In some embodiments, the spray nozzle is fed with liquid under
pressure
through a flexible line, the IR emitter is supplied with electrical power via
suitable electrical
wires.
[00155] In some embodiments, the guides and spray nozzle(s) may be located
upstream of the IR emitter and the liquid feed may be supplied by a pipe or
tube that extends
away from the assembly through the pipe system and out to a reservoir with a
fluid pump and
may also have an electrical supply wire that extends away from the assembly
through the
pipe system and out to an electrical supply suitable for the power
requirements of the IR
emitter and any other devices mounted to the assembly.
[00156] In other embodiments of the invention, a liquid composition comprising
at
least one metal compound may be applied to the selected surfaces of a fluid
flow system
using a motorized pig that is equipped with at least one spray nozzle and one
or more traction
drive devices wherein the motorized pig is moved through a piping system and
sprays the
composition on the insides of the pipe. In some embodiments, the composition
can be
supplied via a reservoir provided within the pig assembly. Means of providing
pressure to
the spray head is also provided using known means such as stored air pressure,
electric
pumps, or similar, and the motive force for the traction drive is provided
using stored air
pressure, electric pumps, or similar. In this implementation, the pig would
travel in a chosen
direction with the spray head being at its rearward end, thus leaving an
uninterrupted liquid
application of the composition on the chosen surfaces of the piping system as
it traveled. In
some iterations of this embodiment, the pig may be moved via a tether or cable
attached to
the pig assembly at a chosen point.
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[00157] In other embodiments, the motive power to move the pig assembly
through the
system to apply a composition to the interior surfaces of the passageway(s)
may be provided
by tension applied to the liquid feed lines, electrical supply wires, a
separate cable of
sufficient strength to pull the assembly, or a combination thereof. The
tension is provided by
known means, in some embodiments, such as an electric motor driven reel device
mounted
outside the piping system and controlled through known means to provide a
desired speed of
travel of the pig assembly while simultaneously providing the liquid coating
material at a
desired delivery rate through the feed line and providing any necessary
electrical current flow
at a chosen voltage through optional electrical feed wires that run from the
reel device to the
assembly. In some implementations of this embodiment the coating assembly may
first move
to a chosen location within a pipe, passageway, or piping system through the
use of gaseous
pressure acting against a pigging device attached to the coating assembly such
that the
pigging device acts as a partial or full plug to the pipe's cross section and,
when pressure is
applied to the interior of the pipe upstream of the pigging device, the
difference in pressure
between the upstream portions and the downstream portions with respect to the
pigging
device cause its movement toward the lower pressure zone. In this manner, the
pigging
device and the attached coating assembly, which may incorporate guides, spray
nozzle, and
IR emitter, or a combination thereof, may be moved to a chosen location within
the piping
system and then retracted using tension provided onto at least one of the feed
lines or wires.
[00158] In some embodiments of the invention there may be a vaporization phase
created after the liquid coating material is applied to the inner surfaces of
the pipe wherein
the wetted surfaces are exposed to an ambient pressure near to or lower than
the vapor
pressure of the liquid coating material, resulting in at least some of the
liquid coating material
to change from the liquid phase to the vapor phase, followed by a rise in
absolute pressure
within the system causing at least a portion of the vaporous phase coating
material to
condense on at least some of the inner surfaces of the pipe, said process
greatly aiding the
even distribution of the coating material over the inner surfaces of the pipe.
In some
implementations of this embodiment, the vaporization of at least some of the
liquid coating
material may be achieved through the use of a vacuum pump system that is
fluidically
connected to the interior volume of a pipe system and allowed to evacuate the
interior volume
created by the inner surfaces of the pipe and corresponding seals or plugs
that may be
provided at any open ends or ports within the piping system. In further
implementations of
this embodiment, the reduction in local pressure within the interior of a
piping system and its
full or partial restoration to ambient pressure may be achieved through known
control
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systems using one or more vacuum pumps, or through the use of ports and valves
operated
through manual, semi-automatic, or automatic means known to those skilled in
the art of
industrial process control. In some embodiments, the required vacuum may be
provided by
any one of a variety of known vacuum-producing systems including, but not
limited to,
pumps, blowers, molecular drag systems, turbo-molecular systems, cryosorption
processes,
sputter-ion pump, and similar.
[00159] In some iterations of this embodiment the reduction in pressure within
the
pipe's interior may be provided through a reduction in temperature of the
piping system while
the system is completely sealed, taking advantage of the natural reduction in
pressure and
volume that will occur as a sealed system is allowed to cool and the internal
gases contract in
accordance with the Ideal Gas Law, expressed as
PV = nRT
where P = pressure
V= volume
n = number of moles of gas
R = gas constant (8.314 m3 -Pa =K-1 mol") and
T = temperature
such that a reduction in temperature of a selected molar quantity of gas
within a sealed
system will result in a lowering of its absolute pressure, proportional to the
reduction in
temperature.
[00160] In this implementation of one embodiment, the high temperature used to
convert the liquid coating material to a useable surface treatment may also be
used to create
the required vacuum for dispersion of the next cycle of coating application by
first heating
the piping system using a suitable heating means, for example, a furnace, then
sealing the
pipe ends and any ports, trapping ambient air inside of the pipe along its
length, then allowing
the pipe and contained air to cool to a desired temperature wherein the
contraction of the air
trapped inside the sealed pipe would cause the pressure to drop to desired
levels, then the
introduction of a liquid coating material through chosen ports or passageways
would result in
the liquid's vaporization. In some iterations of this embodiment, additional
evacuation may
be necessary to achieve the desired vacuum levels.
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[00161] In some embodiments, the low pressure that develops within the sealed
pipe
system may need to be bled off to prevent the pressure level from decreasing
below a chosen
level which might cause unwanted stresses or other vacuum-related problems to
be imposed
upon the piping system. In some iterations of this embodiment the pipe may be
filled with a
chosen gas, such as an inert gas, prior to the sealing and cooling operation
so that the liquid
coating material, once introduced into the pipe system, will be vaporized in
an atmosphere
other than normal air inside the pipe. In one iteration of this embodiment, an
inert gas, as an
example, nitrogen, may be used to completely or partially fill the pipe, and
would provide an
inert atmosphere for the vaporization of the liquid coating material such that
the subsequent
heating operation results in the conversion of the liquid matter into a
coating with the desired
characteristics. In other iterations of this embodiment, a reducing gas such
as hydrogen may
be introduced into the piping system prior to cooling and injection of the
liquid coating
material such that the subsequent heating operation results in the conversion
of the liquid
matter into a coating with desired characteristics. In some iterations of this
embodiment, the
heating process may be achieved using known methods such as external heating
via
induction, internal heating using flow gases or liquids at chosen
temperatures, via microwave
emissions, via flame impingement on the exterior or interior of the system,
and similar
methods.
[00162] In one embodiment of the invention, a piping system may be coated
through
the use of vapor deposition of a coating material by first sealing off a
chosen segment of a
piping system or component, then evacuating the inner volume of the sealed
piping system to
a chosen level of vacuum, then by the introduction of a liquid formulation
comprised of the
desired coating material, said liquid formulation becoming vaporized as it is
introduced into
the evacuated inner volume of the piping system wherein sufficient liquid is
allowed to pass
into the inner volume of the piping system to achieve full or partial
saturation of the gases
remaining in the inner volume, then, through the introduction of a chosen gas,
for example,
nitrogen, the pressure within the sealed piping system is allowed to rise to a
chosen level,
resulting in the condensation of the vapor phase coating material into liquid
phase coating
material, said condensation resulting in the even wetting of the interior
surfaces of the sealed
system. In some implementation of this embodiment, the condensation process if
followed by
the heating of these wetted surfaces to a temperature sufficient to convert at
least a portion of
the at least one metal compound into at least one metal oxide coating.
[00163] In some iterations of this embodiment, multiple layers of similar or
differing
metal oxide coatings may be achieved using repeated cycles of the vaporization
and
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condensation process described above. In other iterations of this embodiment,
additional
layers of coating material may be applied to a chosen surface using a
combination of known
methods to achieve the desired final coating construction, for example,
spraying on at least
one metal compound and then converting it to at least one metal oxide may be
followed by
vapor deposition of a subsequent film which may be followed by additional
layers using a
chosen application method described within this application or using an
alternate method as
desired.
[00164] In some embodiments, the method of the invention can include a pre-
application cleaning step prior to the application of the composition. In
these embodiments,
the invention involves the application of one or more cleaning materials,
which may be in
vapor, liquid, semi-solid phase, or a combination of these to at least a
portion of the surfaces
of the final system, followed by a flushing and drying cycle at a drying
temperature. The
cleaning technique can be of the type used for cleaning surfaces prior to
coating, plating,
painting, or similar surface treatments. The pre-application cleaning step may
also include a
pickling operation using known chemicals and process in order to prepare the
surface(s) for
coating.
[00165] Certain embodiments employ a cleaning composition that comprises one
or
more acids. Other embodiments employ a cleaning composition that comprises one
or more
carboxylic acids. In further embodiments, one or more pigs contact a cleaning
composition
and is placed into launching communication with the pipe to be treated. Then
the pig(s) is
driven through the pipe, allowing the cleaning composition to contact, and
thereby clean, the
interior of the pipe. Optionally, the same or different pigs can pass through
the pipe more
than once, contacting the interior surface of the pipe with the same or
different cleaning
composition. For example, a first cleaning composition could be an acid, and a
second
cleaning composition could be water or a mild base to neutralize the acid.
Optionally, the
cleaning composition(s) is removed by any suitable method, such as, for
example, flushing
with fluid such as water, dry air, and/or nitrogen, and/or by heating the
environment inside
the pipe to drive off the cleaning composition(s). In one embodiment, the
environment inside
the pipe contacted with a cleaning composition is heated to about 400 C to
about 427 C in
the presence of nitrogen, cooled, and flushed with nitrogen or dry air.
Heating can be done in
the presence of nitrogen, in certain cases, to limit the reaction of the
surface with oxygen
and/or water at the heating temperature. The cleaning composition is
substantially removed
when any remaining amount or residue would not interfere with the use of the
pipe or the
further treatment (such as forming a metal oxide) of the pipe.
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[00166] In another embodiment, spherical sponges are soaked with a cleaning
composition and individually passed through a pipe to be cleaned and removed
at the other
end of the pipe, driven by compressed air. After one, two, three, four or more
passes, the
pipe is sealed, flushed with nitrogen, and heated to remove the cleaning
composition. Upon
cooling, the pipe can be cleaned further, or a coating composition can contact
the interior of
the pipe in accordance with other embodiments of the present invention
disclosed herein.
[00167] Thus, some embodiments provide a method for cleaning the interior
surface
of a pipe, comprising:
placing a first pig proximate to the interior surface of the pipe,
wherein the first pig is a compressible sponge having a diameter in an
uncompressed state at least about 1.4 times the largest inner diameter
of the pipe;
applying a first cleaning composition to the interior surface with the first
pig, thereby
cleaning the interior surface,
wherein the first cleaning composition comprises a carboxylic acid; and
substantially removing the first cleaning composition from the interior
surface.
[00168] In further embodiments, the foregoing method further comprises, before
substantially removing the first cleaning composition,
placing a second pig proximate to the interior surface of the pipe; and
applying a second cleaning composition to the interior surface with the second
pig,
wherein substantially removing the first cleaning composition also
substantially removes the second cleaning composition.
[00169] The diameter, in this case, refers to the diameter relative to the
cross section of
the pipe to be treated. Thus, an oblong or bullet shaped pig has a diameter
relative to the
pipe's inner diameter, considering the orientation the pig will adopt inside
the pipe. The
diameter in general can be any suitable diameter that allows the pig to
maintain a seal in the
pipe, so a fluid such as compressed air can propel the pig through the pipe.
In some cases,
the diameter of the compressible sponge is about 1.4 times, about 2 times, or
about 3.5 times
the maximum inner diameter of the pipe to be treated. Those diameters refer to
the sponge in
an uncompressed state. In certain embodiments, the compressible sponge is
spherical in an
uncompressed state.
[00170] Some other embodiments employ a cleaning composition that comprises
one
or more carboxylic acids. In further embodiments, the cleaning composition
comprises acetic
acid, formic acid, propionic acid, 2-ethylhexanoic acid, or a combination of
two or more
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thereof. In still further embodiments, the first cleaning composition consists
essentially of 2-
ethylhexanoic acid. When describing a first and second cleaning composition,
the second
cleaning composition can be the same or different from the first cleaning
composition.
[00171] Additional embodiments provide a method for forming at least one metal
oxide on an interior surface of an industrial fluid processing or transport
system or a
component thereof, comprising:
placing at least one first pig proximate to the interior surface of the
industrial fluid
processing or transport system or the component thereof;
applying at least one cleaning composition to the interior surface with the at
least one
first pig;
substantially removing the at least one cleaning composition from the interior
surface;
placing at least one second pig proximate to the interior surface of the
industrial fluid
processing or transport system or the component thereof;
applying at least one metal compound to the interior surface with the at least
one
second pig; and
converting at least some of the at least one metal compound to at least one
metal
oxide.
[00172] Still other embodiments of the present invention employ at least two
applications of the same or different metal compounds to the interior surface
of an industrial
fluid processing or transport system, such as a pipe, wherein two different
temperatures are
used. Thus, certain embodiments provide a method for forming at least one
metal oxide on
an interior surface of an industrial fluid processing or transport system or a
component
thereof, comprising:
placing at least one first pig proximate to the interior surface of the
industrial fluid
processing or transport system or the component thereof;
applying at least one first metal compound to the interior surface with the at
least one
first pig;
heating the environment of the interior surface to a temperature ranging from
about
400 C to about 427 C;
placing at least one second pig proximate to the interior surface of the
industrial fluid
processing or transport system or the component thereof;
applying at least one second metal compound to the interior surface with the
at least
one second pig,
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wherein the at least one first metal compound and at least one second metal
compound are the same or different; and
heating the environment of the interior surface to a temperature ranging from
about
438 C to about 604 C, thereby forming at least one metal oxide on the
interior
surface.
[00173] Some embodiments of the present invention provide a method for
decreasing
or preventing fouling on a surface of a sensor, or a component thereof.
Further embodiments
provide a sensor comprising at least one surface comprising at least one metal
oxide. In still
further embodiments, the at least one surface of the sensor comprises at least
one metal oxide,
in which at least some of the at least one metal oxide is present in a
diffused coating. Sensors
may contain more than one part, including but not limited to the sensing
element(s),
mounting structures, and feedback means such as for example wiring which may
be in
protective cladding. Each of those parts have surfaces that may benefit from a
metal oxide
coating; one or more of those surfaces can be coated in accordance with the
invention.
Sensors that appear in embodiments of the present invention include, but are
not limited to,
sight glasses, for example a sight glass on a boiler, thermocouples,
resistance thermal devices
(RTDs), pressure sensors, flow rate and mass flow sensors, airspeed sensors,
piezoelectric
sensors, photo-optic combustion sensors, high temperature chromatographs,
optical sensors,
UV sensors, infra red sensors, electromagnetic field sensors, electromagnetic
wave sensors,
radiation sensors, toxic chemical sensors, gas analyzers, oxygen sensors,
nitrogen sensors,
NOx sensors, SOX sensors, CO2 sensors, CO sensors, diesel exhaust soot
sensors, other soot
sensors, H2S sensors, and humidity sensors, among others. Care should be taken
so that the
applying of the at least one metal compound and the converting to at least one
metal oxide
are accomplished to minimize or avoid damage to the sensor, or to avoid
inhibiting sensor
operation. Damage can be minimized or avoided, in some embodiments, by
converting at a
lower temperature, or without substantially heating the surface.
Alternatively, in other
embodiments, non-sensing element surfaces can receive at least one metal oxide
coating
before the sensing element(s) is/are assembled into the sensor.
[00174] Some embodiments of the present invention provide a metal oxide
coating on
a surface that is subject to coke buildup. Such surfaces include, but are not
limited to, one or
more surfaces of:
the heaters, heat exchangers, vacuum tower, and pipes that contact the heavier
fractions in a
crude unit or a vacuum unit;
the furnace, heater tubes, furnace outlets, and pipes of an ethylene cracker
unit;
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the heaters, heater tubes, fractionator bottoms, stripper bottoms, heat
exchangers, and pipes of
a delayed coker unit or a viscosity breaker;
the cyclone dip legs and stripper baffles of the reactor, the reactor overhead
line, the spent
catalyst return line, the plenum of the catalyst regenerator, and the bottom
and lower trays of
the fractionator of a fluid catalytic cracking unit;
the heaters, heater tubes, reactors, product pipes, catalyst transfer pipes,
and valves of a
continuous catalytic reforming unit;
the heaters, heater tubes, reactors, and pipes in a fixed bed catalytic
reforming unit; and
the reactors, heaters, heat exchangers, and pipes of a syngas generation unit.
[00175] Other embodiments provide a metal oxide coating on a surface that is
subject
to corrosive attack by one or more species present in the process stream. Such
surfaces
include, but are not limited to, one or more surfaces of.
the furnaces, towers, strippers, reheaters, heat exchangers, and pipes of a
crude unit or a
vacuum unit;
the fractionators, strippers, compressors, heat exchangers, and pipes of a
delayed coker unit;
a fractionator and pipes therefrom of a fluid catalytic cracking unit;
on the knock-out drums, pipes, compressors, reheaters, and heat exchangers of
a catalytic
cracker's light ends recovery unit;
the heat exchangers, product separators, debutanizer, overhead condensers,
overhead drums,
and pipes of a continuous catalytic reforming unit;
the reactors, stabilizers, accumulators, heat exchangers, and pipes of a fixed
bed catalytic
reforming unit;
the reactors, heaters, water washers, separators, hydrogen recycle
compressors, strippers, heat
exchangers, pumps, and pipes of a hydrotreating, hydrodesulfuring, or
hydrocracking unit;
the trays, pipes, pumps, and bottoms of a sulfuric acid alkylation unit,
including the outside
surfaces of pipes that may be enclosed in insulation;
the settler, acid regenerator, acid vaporizer, fractionator, reboiler,
strippers, condensers,
recyclers, heat exchangers, defluorinators, KOH treaters, pumps, and pipes of
an HF or
sulfuric acid alkylation unit; and
the reactor, separator, pumps, and pipes of a biodiesel refining unit.
[00176] The skilled artisan will appreciate that more than one mechanism can
operate
to degrade the same surface. Accordingly, the foregoing embodiments do not
suggest
exclusive mechanisms for any given surface.
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[00177] Still other embodiments of the present invention provide methods for
reducing
or preventing combustion buildup on a flame-heated surface of a fluid
processing or transport
system, or a component thereof. That combustion buildup can be any material
that deposits
on such surfaces, including, for example, slag, scale, coke, soot, and
combinations thereof. A
flame-heated surface includes any surface exposed to fuel combustion and its
products, such
as, for example, those surfaces exposed to the flame, smoke, soot, and/or
fumes of
combustion, even if that surface is not directly contacted by a flame. Such
surfaces include,
but are not limited to, insides of furnaces, preheaters, reheaters, and smoke
stacks; outsides of
boilers, heater tubes, and flame-heated reactors; as well as fuel conduits,
valves, vents,
burners, combustion control devices, ash conduits, and the like proximate to
the combustion
area. A flame-heated surface does not necessarily include process fluid-
contacting surfaces.
To illustrate, it is contemplated that heat is transferred from the flame-
heated surface through
the vessel wall to the process fluid-contacting surface. Thus, a vessel wall
has in general two
surfaces, the flame-heated surface and the process fluid-contacting surface.
[00178] Further embodiments provide methods for reducing or preventing fouling
of at
least one metal surface of a combustion engine system, or a component thereof.
Combustion
engine systems include, but are not limited to, internal combustion engines,
two-stroke
engines, four-stroke engines, gasoline engines, diesel engines, turboprop
engines, jet engines,
gas turbines, and rocket engines. Suitable metal surfaces include, but are not
limited to, jet,
turbojet, turbofan, ram jet, scram jet, and turbine engine surfaces including
inlet, compressor,
turbine, blades, recuperators, afterburner, nozzle, thrust vector surfaces,
and fuel delivery
components; internal combustion engine surfaces including pistons, rotors,
cylinders,
housings, piston rings, seals, endplates, cylinder heads, valve heads, valve
stems, valve seats,
valve faces, valve train components, cams, pushrods, cam followers, rocker
arms, valve
springs, valve guides, combustion chambers, crankcases, intake system
components,
supercharger components, exhaust manifolds, exhaust gas recirculation pipes
and valves,
turbocharger components, catalytic converter components, exhaust pipes, fuel
injectors, and
fuel pumps; and rocket engine surfaces including inlets, fuel delivery
systems, fuel
combustion zones, and thrust vector surfaces. In some embodiments, the metal
oxide coating
of the metal surface of a combustion engine system is an oxidizing coating. In
further
embodiments, the metal oxide coating further comprises at least one metal.
Metals that may
be desired, such as for catalytic purposes, for example, include but are not
limited to
platinum, palladium, rhodium, nickel, cerium, gold, silver, zinc, lead,
rhenium, ruthenium,
and combinations of two or more thereof.
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[00179] Still other embodiments provide a fluid processing or transport system
comprising at least one surface comprising at least one metal oxide coating,
in which the
system has a large size. A large size is useful for commercial scale
processes. Industrial
fluid processing or transport systems include, but are not limited to, oil
refineries; oil refinery
subsystems such as crude units, atmospheric units, vacuum units, delayed
cokers, fluid
catalytic crackers, fixed bed catalytic crackers, continuous catalytic
reformers, naphtha
reformers, hydrotreaters, hydrocrackers, alkylators including sulfuric acid
alkylators and HF
alkylators, amine treaters, sulfur recovery units, sour water strippers,
isomerization units, and
hydrogen reforming units; waste water treatment plants; cooling water systems
such as those
found in manufacturing plants and power plants; desalinization plants; and
processing
systems found in colorants manufacturing, cosmetics manufacturing, food
processing,
chemical manufacturing, pharmaceutical manufacturing, and the like.
[00180] In some embodiments, the surface of the fluid processing or transport
system
to receive a metal oxide coating in accordance with the present invention has
a surface area
greater than about 100 square feet. In other embodiments, the surface area
ranges between
about 100 square feet to about 500 square feet, between about 500 square feet
to about 1,000
square feet, between about 1,000 square feet to about 10,000 square feet,
between about
10,000 square feet to about 20,000 square feet, between about 20,000 square
feet to about
50,000 square feet, between about 50,000 square feet to about 100,000 square
feet, between
about 100,000 square feet to about 1,000,000 square feet, between about
1,000,000 square
feet to about 10,000,000 square feet, between about 10,000,000 square feet to
about 1 square
mile, between about 1 square mile to about 5 square miles, between about 5
square miles to
about 10 square miles, or greater than about 10 square miles.
[00181] The surface to be treated according to the invention also can be
pretreated, in
further embodiments, before the application of the composition. In some cases,
the surface
can be etched according to known methods, for example, with an acid wash
comprising nitric
acid, sulphuric acid, hydrochloric acid, phosphoric acid, carboxylic acid, or
a combination of
two or more thereof, or with a base wash comprising sodium hydroxide or
potassium
hydroxide, for example. In further cases, the surface can be mechanically
machined or
polished, with or without the aid of one or more chemical etching agents,
abrasives, and
polishing agents, to make the surface either rougher or smoother. In still
further cases, the
surface can be pretreated such as by carburizing, nitriding, painting, powder
coating, plating,
or anodizing. Thin films of chrome, tin, and other elements, alone or in
combination, can be
deposited, in some embodiments. Methods for depositing thin films are well
known and
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include chemical vapor deposition, physical vapor deposition, molecular beam
epitaxy,
plasma spraying, electroplating, ion impregnation, and others.
[00182] In some embodiments of the present invention, a metal compound
comprises a
transition metal atom. In other embodiments, a metal compound comprises a rare
earth metal
atom. In further embodiments, the metal compound composition comprises a
plurality of
metal compounds. In some embodiments, a plurality of metal compounds comprises
at least
one rare earth metal compound and at least one transition metal compound,
while in other
embodiments, a plurality of metal compounds comprises other than at least one
rare earth
metal compound and at least one transition metal compound. Metal carboxylates,
metal
alkoxides, and metal (3-diketonates can be chosen for some embodiments of the
present
invention.
[00183] In further embodiments, a metal compound mixture comprises one metal
compound as its major component and one or more additional metal compounds
which may
function as stabilizing additives. Stabilizing additives, in some embodiments,
comprise
trivalent metal compounds. Trivalent metal compounds include, but are not
limited to,
chromium, iron, manganese, and nickel compounds. A metal compound composition,
in
some embodiments, comprises both cerium and chromium compounds.
[00184] In some embodiments, the metal compound that is the major component of
the
metal compound composition contains an amount of metal that ranges from about
65 to about
97% by weight or from about 80 to about 87% by weight of the total weight of
metal in the
composition. In other embodiments, the amount of metal forming the major
component of
the metal compound composition ranges from about 90 to about 97% by weight of
the total
metal present in the composition. In still other embodiments, the amount of
metal forming
the major component of the metal compound composition ranges from about 97 to
about
100% by weight of the total metal present in the composition.
[00185] The metal compounds that may function as stabilizing additives, in
some
embodiments, may be present in amounts such that the total amount of the metal
in metal
compounds which are the stabilizing additives is at least 3% by weight,
relative to the total
weight of the metal in the metal compound composition. This can be achieved in
some
embodiments by using a single stabilizing additive, or multiple stabilizing
additives, provided
that the total weight of the metal in the stabilizing additives is greater
than 3%. In other
embodiments, the amount of the stabilizing metal is less than 3 % relative to
the total weight
of metal in the metal compound composition. In yet other embodiments, the
total weight of
the metal in the stabilizing additives ranges from about 3% to about 35% by
weight. In still
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other embodiments, the total weight for the metal in the stabilizing additives
ranges from
about 3 to about 30% by weight, relative to the total weight of the metal in
the metal
compound composition. In other embodiments, the total weight range for the
metal in the
stabilizing additives ranges from about 3 to about 10% by weight. In some
embodiments, the
total weight range for the metal in the stabilizing additives is from about 7
to about 8% by
weight, relative to the total weight of the metal in the metal compound
composition. Still
other embodiments provide the stabilizing metal in an amount greater than
about 35 % by
weight relative to the total weight of the metal in the metal compound
composition.
[00186] The amount of metal in the metal compound composition, according to
some
embodiments, ranges from about 20 to about 150 grams of metal per kilogram of
metal
compound composition. In other embodiments, the amount of metal in the metal
compound
composition ranges from about 30 to about 50 grams of metal per kilogram of
metal
compound composition. In further embodiments, the metal compound composition
can
contain from about 30 to about 40 grams of metal per kg of composition.
Amounts of metal
less than 20 grams of metal per kilogram of metal compound composition or
greater than
about 150 grams of metal per kilogram of metal compound composition also can
be used.
[00187] The metal compound may be present in any suitable composition. Finely
divided powder, nanoparticles, solution, suspension, multi-phase composition,
gel, vapor,
aerosol, and paste, among others, are possible.
[00188] The metal compound composition may also include nanoparticles in the
size
range of less than 100 nm in average size and being composed of a variety of
elements or
combination thereof, for example, A1203, CeO2, Ce203, Ti02, Zr02 and others.
In some
cases, the nanoparticles can be dispersed, agglomerated, or a mixture of
dispersed and
agglomerated nanoparticles. Nanoparticles may have a charge applied to them,
negative or
positive, to aid dispersion. Moreover, dispersion agents, such as known acids
or surface
modifying agents, may be used. The presence of nanoparticles may decrease the
porosity of
the final coating; the level of porosity will generally decrease with
increasing quantity and
decreasing size of the included nanoparticles. Coating porosity can also be
influenced by
applying additional coating layers according to the process of the invention;
porosity will
generally decrease with an increasing number of layers. In some embodiments
the
nanoparticles may be first mixed with a liquid and then mixed with the
compound
composition; this method provides a means to create a fine dispersion in a
first liquid which
retains its dispersion when mixed with a second, or third liquid. For example,
nanoparticles
of chosen elements, oxides, molecules, or alloys may be dispersed into a first
liquid and, after
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a desired quality of dispersion is achieved, the nanoparticles in the first
liquid may be mixed
with the liquid metal compound composition prior to the exposure of the final
composition to
an environment that will convert at least a portion of the metal compound(s)
into metal
oxides. The result may be a more dense film with reduced porous sites.
[00189] The applying of the metal compound composition may be accomplished by
various processes, including dipping, spraying, flushing, vapor deposition,
printing,
lithography, rolling, spin coating, brushing, swabbing (e.g., with an
absorbent "pig" of fabric
or other material that contains the metal compound composition and is drawn
through the
apparatus), pig train (in which the metal compound composition, trapped
between two or
more pigs, is pushed through a system by compressed air, for example), or any
other means
that allows the metal compound composition to contact the desired portions of
the surface to
be treated. In this regard, the metal compound composition may be liquid, and
may also
comprise a solvent. The optional solvent may be any hydrocarbon and mixtures
thereof. In
some embodiments, the solvent can be chosen from carboxylic acids; toluene;
xylene;
benzene; alkanes, such as for example, propane, butane, isobutene, hexane,
heptane, octane,
and decane; alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-
butanol, and
isobutanol; mineral spirits; (3-diketones, such as acetylacetone; ketones such
as acetone; high-
paraffin, aromatic hydrocarbons; and combinations of two or more of the
foregoing. Some
embodiments employ solvents that contain no water or water in trace amounts or
greater,
while other embodiments employ water as the solvent. In some embodiments, the
metal
compound composition further comprises at least one carboxylic acid. Some
embodiments
employ no solvent in the metal compound composition. Other embodiments employ
no
carboxylic acid in the metal compound composition.
[00190] The metal compound composition can applied in some embodiments in
which
the composition has a temperature less than about 250 C. That composition
also can be
applied to the substrate in further embodiments at a temperature less than
about 50 C. In
other embodiments, the liquid metal compound composition is applied to the
substrate at
room temperature. In still other embodiments, that composition is applied at a
temperature
greater than about 250 C.
[00191] Following application, the at least one metal compound is at least
partially
converted to at least one metal oxide. In some embodiments the at least one
metal compound
is fully converted to at least one metal oxide.
[00192] Suitable environments for converting the at least one metal compound
into at
least one metal oxide include vacuum, partial vacuum, atmospheric pressure,
high pressure
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equal to several atmospheres, high pressure equal to several hundred
atmospheres, inert
gases, and reactive gases such as gases comprising oxygen, including pure
oxygen, air, dry
air, and mixtures of oxygen in various ratios with one or more other gases
such as nitrogen,
carbon dioxide, helium, neon, and argon, as well as hydrogen, mixtures of
hydrogen in
various ratios with one or more other gases such as nitrogen, carbon dioxide,
helium, neon,
and argon, also other gases such as, for example, nitrogen, NH3, hydrocarbons,
H2S, PH3,
each alone or in combination with various gases, and still other gases which
may or may not
be inert in the converting environment. In some embodiments, a suitable
environment for
converting the at least one metal compound into at least one metal oxide is
free or
substantially free of oxygen.
[00193] The environment may be heated relative to ambient conditions, in some
embodiments. In other embodiments, the environment may comprise reactive
species that
cause or catalyze the conversion of the metal compound to the metal oxide,
such as, for
example, acid-catalyzed hydrolysis of metal alkoxides. In still other
embodiments, the metal
compound is caused to convert to the metal oxide by the use of induction
heating, lasers,
microwave emission, or plasma, as explained below.
[00194] The conversion environment may be accomplished in a number of ways.
For
example, a conventional oven may be used to bring the coated substrate up to a
temperature
exceeding approximately 250 C for a given period of time. In some embodiments,
the
environment of the coated substrate is heated to a temperature exceeding about
400 C but less
than about 450 C or less than about 500 C for a chosen period of time. In
other
embodiments, the environment of the coated substrate is heated to a
temperature ranging
from about 400 C to about 650 C. In further embodiments, the environment is
heated to a
temperature ranging from about 400 C to about 550 C. In still further
embodiments, the
environment is heated to a temperature ranging from about 550 C to about 650
C, from
about 650 C to about 800 C, or from about 800 C to about 1000 C. In one
embodiment,
the environment is heated to a temperature of up to about 425 C or 450 C.
Depending on the
size of the components and/or process equipment, pipes, etc., the time period
may be
extended such that sufficient conversion of a desired amount of the metal
compound to metal
oxides has been accomplished.
[00195] In some applications, the oxidation of the surface being treated is
not desired.
In these cases, an inert atmosphere may be provided in the conversion
environment to prevent
such oxidation. In the case of heating the component in a conventional oven, a
nitrogen or
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argon atmosphere can be used, among other inert gases, to prevent or reduce
the oxidation of
the surface prior to or during the conversion process.
[00196] The conversion environment may also be created using induction heating
through means familiar to those skilled in the art of induction heating.
Alternatively, the
conversion environment may be provided using a laser applied to the surface
area for
sufficient time to allow at least some of the metal compounds to convert to
metal oxides. In
other applications, the conversion environment may be created using an infra-
red light source
which can reach sufficient temperatures to convert at least some of the metal
compounds to
metal oxides. Some embodiments may employ a microwave emission device to cause
at least
some of the metal compound to convert. Still other embodiments employ a plasma
to provide
the environment for converting the metal compound into metal oxide. In the
case of
induction heating, microwave heating, lasers, plasmas, and other heating
methods that can
produce the necessary heat levels in a short time, for example, within
seconds, 1 minute, 10
minutes, 20 minutes, 30 minutes, 40 minutes, or one hour. Accordingly, in some
embodiments, the conversion environment can be created without the use of an
inert gaseous
environment, thus enabling conversion to be done in open air, outside of a
closed system due
to the reduced time for undesirable compounds to develop on the material's
surface in the
presence of ambient air.
[00197] The gas above the metal compound on the surface can be heated, in some
embodiments, to convert the metal compound to the metal oxide. Heating can be
accomplished by introducing high temperature process gases, which are fed
through the
assembled fluid transport or processing system, wherein the joints, welds,
connections, and
one or more interior surfaces of the fluid transport or processing system
become covered with
a protective thin film of the desired metal oxide(s). This high temperature
gas can be
produced by a conventional oven, induction heating coils, heat exchangers,
industrial process
furnaces, exothermic reactions, microwave emission, or other suitable heating
method.
[00198] If there are elements of the assembled process system and components
or
surfaces on which it is not desired to have nanocrystalline layer applied
(e.g. fluid beds,
catalytic surfaces, etc.), these can be temporarily bypassed using known
methods of piping,
valves, ports, etc. during one or more steps of the method of the invention,
be it during the
application of a composition to the inner surfaces or during the high
temperature conversion
stage, or a combination thereof. Likewise, areas that are to be kept free of
the coating of the
invention can be masked-off using known means prior to the application of the
method's
composition and its conversion using some heat or energy source.
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[00199] In other applications, the metal compound composition may be applied
to
chosen areas of a component or system and an induction heating element may be
passed
proximate to the area of interest to create the conversion environment. In
some applications,
the inner surface of a component may not be visible by line of sight, but an
induction wand
held proximate to the inside or outside surfaces of the component may allow
sufficient heat to
be developed on the wetted surfaces being treated with the metal compounds
such that the
desired oxides are formed by an indirect heating method. This technique would
also be
possible using infra-red heating from inside or outside of a component, flame
heating, or
other known heating methods wherein the material of the component can be
raised to the
desired temperature to ensure the conversion of the metal compounds to oxides.
Using this
method of indirect heating may also be used with a chosen atmosphere that may
be provided
proximate to the wetted surfaces of the pipe or component, such as an inert
atmosphere made
up of argon, as one example, which would serve to prevent undesirable oxides
to form on the
material surface being treated.
[00200] In other applications, multiple coats may be desired such that further
protection of the material's surface is provided. To reduce the time between
applications of
the coating of the invention, cooling methods may be used after each heating
cycle to bring
the surfaces to the required temperatures prior to subsequent applications of
the metal
compounds. Such cooling methods may be used that are known to the art such as
water
spraying, cold vapor purging through the interior of the system, evaporative
cooling methods,
and others.
[00201] Representative coating compositions that have been found to be
suitable in
embodiments of the present invention include, but are not limited to:
Zr02 for example, at 0-90 wt%
CeO2 for example, at 0-90 wt%
Ce02-ZrO2 where CeO2 is about 10-90 wt%
Y203 Yttria-stabilized Zirconia where Y is about 1-50% mol%
Ti02 for example, at 0-90 wt%
Fe203 for example, at 0-90 wt%
NiO for example, at 0-90 wt%
A1203 for example, at 0-90 wt%
Si02
Y203
Cr203
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Mo203
Hf02
La203
Pr203
Nd203
Sm203
Eu203
Gd203
Tb203
Dy203
Ho203
Er203
Tm203
Yb203
Lu203
Mixtures of these compositions are also suitable for use in the invention.
[00202] Oxides of the following elements also can be used in embodiments of
the
present invention: Lithium, Beryllium, Sodium, Magnesium, Aluminum, Silicon,
Potassium,
Calcium, Scandium, Titanium, Vanadium, Chromium, Manganese, Iron, Cobalt,
Nickel,
Copper, Zinc, Gallium, Germanium, Arsenic, Bromine, Rubidium, Strontium,
Yttrium,
Zirconium, Niobium, Molybdenum, Technetium, Ruthenium, Rhodium, Palladium,
Antimony, Tellurium, Silver, Cadmium, Indium, Tin, Cesium, Barium, Lanthanum,
Cerium,
Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium,
Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Hafnium, Tantalum,
Tungsten, Rhenium, Osmium, Iridium, Platinum, Gold, Mercury, Thallium, Lead,
Bismuth,
Radium, Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium,
Americium,
Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium,
and
Lawrencium. Oxides containing more than one of the foregoing elements, and
oxides
containing elements in addition to the foregoing elements, also can be used in
embodiments
of the present invention. For example, SrTiO3 and MgA12O4 are included. Those
materials
are likely to form at least in small amounts when appropriate metal compounds
are used,
depending on the conditions of the conversion process. In some embodiments,
the molar
ratio of metal compounds deposited on the surface corresponds to the molar
ratio of metal
oxides after conversion.
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[00203] The invention relates, in some embodiments, to diffused coatings and
thin
films (and articles coated therewith) containing at least one rare earth metal
oxide, and at
least one transition metal oxide. As used herein, "diffused" means that metal
oxide
molecules, nanoparticles, nanocrystals, larger domains, or more than one of
the foregoing,
have penetrated the substrate. The diffusion of metal oxides can range in
concentration from
rare interstitial inclusions in the substrate, up to the formation of
materials that contain
significant amounts of metal oxide. A thin film is understood to indicate a
layer, no matter
how thin, composed substantially of metal oxide. In some embodiments, a thin
film has very
little or no substrate material present, while in other embodiments, a thin
film comprises
atoms, molecules, nanoparticles, or larger domains of substrate ingredients.
In some
embodiments, it may be possible to distinguish between diffused portions and
thin films. In
other embodiments, a gradient may exist in which it becomes difficult to
observe a boundary
between the diffused coating and the thin film. Furthermore, some embodiments
may exhibit
only one of a diffused coating and a thin film. Still other embodiments
include thin films in
which one or more species have migrated from the substrate into the thin film.
The terms
"metal oxide coating" and "surface comprises at least one metal oxide" include
all of those
possibilities, including diffused coatings, thin films, stacked thin films,
and combinations
thereof.
[00204] As explained herein, the diffused coating of some embodiments of the
invention provides increased performance, in part, because it penetrates the
surface of the
coated substrate to a depth providing a firm anchor to the material being
coated without the
need for intermediate bonding layers. In some embodiments, the diffused
coating penetrates
the substrate to a depth of less than about 100 Angstroms. In other
embodiments, the
diffused coating penetrates from about 100 Angstroms to about 200 Angstroms,
from about
200 Angstroms to about 400 Angstroms, from about 400 Angstroms to about 600
Angstroms,
and greater than about 600 Angstroms, and in some embodiments from about 200
to about
600 Angstroms. This diffused coating allows much thinner films [in some
embodiments
around 0.1 to 1 microns in thickness (or about 0.5 microns when approximately
6 layers are
used)] to be applied, and yet may provide equivalent protection to that
provided by
conventional coating or thin film technologies. This, in turn, allows for
thinner films or
coatings to be established, reducing significantly the cost of materials
attaching to the
substrate. Thus, some embodiments of the present invention provide a thin film
no thicker
than about 5 nm. Other embodiments provide a thin film no thicker than about
10 nm. Still
other embodiments provide a thin film no thicker than about 20 nm. Still other
embodiments
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provide a thin film no thicker than about 100 nm. Other embodiments provide a
thin film
having a thickness less than about 25 microns. Still other embodiments provide
a thin film
having a thickness less than about 20 microns. Still other embodiments provide
a thin film
having a thickness less than about 10 microns. Yet other embodiments provide a
thin film
having a thickness less than about 5 microns. Some embodiments provide a thin
film having
a thickness less than about 2.5 microns. Even other embodiments provide a thin
film having
a thickness less than about 1 micron.
[00205] In some embodiments of the invention, the metal oxide coating can
contain
other species, such as, for example, species that have migrated from the
substrate into the
metal oxide coating. In other embodiments, those other species can come from
the
atmosphere in which the at least one metal compound is converted. For example,
the
conversion can be performed in an environment in which other species are
provided via
known vapor deposition methods. Still other embodiments provide other species
present in
or derived from the at least one metal compound or the composition comprising
the
compound. Suitable other species include metal atoms, metal compounds
including those
metal atoms, such as oxides, carbides, nitrides, sulfides, phosphides, and
mixtures thereof,
and the like. The inclusion of other species can be accomplished by
controlling the
conditions during conversion, such as the use of a chosen atmosphere during
the heat
conversion process, for example, a partial vacuum or atmosphere containing 02,
N2, NH3, one
or more hydrocarbons, H2S, alkylthiols, PH3, or a combination thereof.
[00206] Some embodiments of the present invention provide metal oxide coatings
that
are substantially free of other species. For example, small amounts of
carbides may form
along side oxides when, for example, metal carboxylates are converted, if no
special
measures are taken to eliminate the carbon from the carboxylate ligands. Thus,
converting
metal compounds in the presence of oxygen gas, air, or oxygen mixed with other
gases
reduces or eliminates carbide formation in some embodiments of the present
invention. Also,
rapid heating of the conversion environment, such as, for example, by
induction heating,
microwave heating, lasers, plasmas, and other heating methods that can produce
the
necessary heat levels in a short time, reduces or eliminates formation of
other species, in
other embodiments. At least one rapid heating technique is used in combination
with an
oxygen-containing atmosphere in still other embodiments.
[00207] Additional embodiments employ various heating steps to reduce or
eliminate
the formation of other species. For example, carbide formation can be lessened
during metal
oxide formation in some embodiments by applying a metal compound precursor
composition
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containing a metal carboxylate to a surface, subjecting the surface to a low-
temperature bake
at about 250 C under a vacuum, introducing air and maintaining the
temperature, and then
increasing the temperature to about 420 C under vacuum or inert atmosphere to
convert the
metal carboxylate into the metal oxide. Without wanting to be bound by theory,
it is believed
that the low-temperature bake drives off most or all of the carboxylate
ligand, resulting in an
oxide film substantially free of metal carbide.
[00208] Still other embodiments employ more than one layer to achieve at least
one
layer substantially without other species. For example, in some embodiments, a
base coat of
at least one metal oxide is formed from at least one metal carboxylate under
an inert
atmosphere. Such a base coat may contain metal carbides due to the initial
presence of the
carboxylate ligands. Moreover, such a base coat may exhibit good adhesion and
strength, for
example, when the surface comprises a carbon steel alloy. Then, one or more
subsequent
metal compounds are repeatedly applied and converted in an oxygen-containing
atmosphere,
for example, and the subsequent layers of metal oxide form substantially
without metal
carbides. In some embodiments, six or more layers are formed on the base coat.
[00209] In addition, the effect of any mismatches in physical, chemical, or
crystallographic properties (particularly with regard to differences in
thermal expansion
coefficients) may be minimized by the use of much thinner coating materials
and the
resulting films. Furthermore, the smaller crystallite structure of the film (3-
6 nanometers, in
some embodiments) increases Hall-Petch strength in the film's structure
significantly.
[00210] In some embodiments, the present invention provides methods of
reducing
differences in coefficients of thermal expansion between a substrate and a
metal oxide
coating proximal to the substrate. In some embodiments, methods of reducing
differences in
coefficients of thermal expansion between a substrate and at least one metal
oxide comprise
interposing a diffused coating between the substrate and the metal oxide.
Interposing such a
diffused coating comprises applying at least one metal compound to the
substrate, and then at
least partially converting the at least one metal compound to at least one
metal oxide.
[00211] The thermal stability of the metal oxide coating can be tested, in
some
embodiments, by exposing the coated material to thermal shock. For example, a
surface
having a metal oxide coating can be observed, such as by microscopy. Then the
surface can
be exposed to a thermal shock, such as by rapid heating or by rapid cooling.
Rapid cooling
can be caused by, for example, dunking the room-temperature or hotter surface
into liquid
nitrogen, maintaining the surface under liquid nitrogen for a time, and then
removing the
surface from the liquid nitrogen. The surface is then observed again, to look
for signs that the
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metal oxide coating is delaminating, cracking, or otherwise degrading because
of the thermal
shock. The thermal shock test can be repeated to see how many shock cycles a
given metal
oxide coating can withstand before a given degree of degradation, if any, is
observed. Thus,
in some embodiments of the present invention, the at least one metal oxide
coating
withstands at least one, at least five, at least ten, at least twenty-five, at
least fifty, or at least
one hundred thermal shock cycles from room temperature to liquid nitrogen
temperature.
[00212] The nanocrystalline grains resulting from some embodiments of the
methods
of the present invention have an average size, or diameter, of less than about
50 nm. In some
embodiments, nanocrystalline grains of metal oxide have an average size
ranging from about
1 mu to about 40 rim or from about 5 nm to about 30 nm. In another embodiment,
nanocrystalline grains have an average size ranging from about 10 Mn to about
25 nm. In
further embodiments, nanocrystalline grains have an average size of less than
about 10 nm, or
less than about 5 nm.
[00213] In other embodiments, the invention relates to metal oxide coatings
(whether
diffused, thin film, or both diffused and thin film) and articles comprising
such coatings, in
which the coatings contain two or more rare earth metal oxides and at least
one transition
metal oxide. Further embodiments of the invention relate to metal oxide
coatings (and articles
comprising them), containing ceria, a second rare earth metal oxide, and a
transition metal
oxide. Some embodiments relate to metal oxide coatings (and articles
comprising them),
containing yttria, zirconia, and a second rare earth metal oxide. In some
cases, the second rare
earth metal oxide can include platinum or other known catalytic elements.
[00214] In some embodiments, the metal compound applied to the surface
comprises a
cerium compound, and the metal oxide coating comprises cerium oxide (or
ceria). In other
embodiments, the metal compound applied to the surface comprises a zirconium
compound,
and the metal oxide coating comprises zirconia. In yet other embodiments, a
solution
comprising both a cerium compound and a zirconium compound is applied, and the
resulting
metal oxide coating comprises ceria and zirconia. In some cases, the zirconia
formed by the
process of the invention comprises crystal grains having an average size of
about 3-9 nm, and
the ceria formed by the process of the invention comprises crystal grains
having an average
size of about 9-18 nm. The nanostructured zirconia can be stabilized in some
embodiments
with yttria or other stabilizing species alone or in combination. In still
other embodiments, the
metal oxide coating comprises zirconia, yttria, or alumina, each alone or in
combination with
one or both of the others.
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[00215] In additional embodiments, the method of the invention further
includes a step
of applying an organosiloxane-silica composition over the formed oxide coating
and
exposing the coated substrate to an environment that will remove volatile
components from
the composition without decomposing organo-silicon bonds. Moreover, other
treatments can
be performed after the formation of an oxide coating. As explained herein,
additional metal
oxide coatings, which can be the same or different, can be added. In some
embodiments, the
metal oxide(s) can be etched, polished, carburized, nitrided, painted, powder
coated, plated,
or anodized. In some embodiments, the at least one metal oxide serves as a
bond coat for at
least one additional coating. Such additional coatings need not be formed
according to the
present invention. Some embodiments provide a metal oxide bond coat that
allows an
additional coating that would not adhere to the surface as well in the absence
of the bond
coat. In addition, the substrate can be subjected to a thermal treatment,
either before or after
a metal oxide coating is formed on the substrate. For example, a substrate
having a metal
oxide coating in accordance with the present invention can be annealed at high
temperature to
strengthen the substrate. In another example, a substrate can be held near
absolute zero
before or after a metal oxide coating is formed on the substrate. Suitable
temperatures for
thermal treatment range from nearly 0 K to several thousand K, and include
liquid hydrogen,
liquid helium, liquid neon, liquid argon, liquid krypton, liquid xenon, liquid
radon, liquid
nitrogen, liquid oxygen, liquid air, and solid carbon dioxide temperatures,
and temperatures
obtained by mixtures, azeotropes, and vapors of those and other materials.
[00216] The methods of the present invention can be used during or after
manufacturing a given component of a fluid processing or transport system. For
example,
one or more oxide coatings can be applied to a pipe section as it is
manufactured, or after the
pipe is assembled into a fluid processing or transport system. Moreover, in
some
embodiments, the methods of the present invention can be incorporated into
conventional
manufacturing steps. For example, after pipes are welded, often they are
subjected to a heat
treatment to relieve the stresses introduced by the welding process. In some
embodiments of
the present invention, at least one metal compound is applied after welding
and before that
heat treatment. In those embodiments, that one heat treatment converts at
least one metal
compound into at least one metal oxide and relieves welding-induced stresses.
[00217] The process of the invention may permit the use of coatings on a wide
variety
of materials, including application of CeO2 and Zr02 coatings to ceramics
and/or solid metals
previously not thought possible of being coated with these materials. Some
embodiments of
the present invention provide a relatively low temperature process that does
not damage or
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distort many substrates, does not produce toxic or corrosive water materials,
and can be done
on site, or "in the field" without the procurement of expensive capital
equipment.
[00218] Additionally, the nature of the resulting interstitial boundaries of
the
invention's nanocrystalline structures in various embodiments can be comprised
of chosen
ingredients so as to increase ionic conductivity while decreasing electron
conductivity, or can
be comprised of chosen ingredients so as to increase the material's mixed
conductivity, or to
modify its porosity. In a similar fashion, many other properties may be
altered through the
judicious selection of various ingredients that are formulated as part of the
metal compound
composition of the invention.
[00219] In some embodiments of the present invention, a substrate which
comprises at
least a portion of a component's structure is placed within a vacuum chamber,
and the
chamber is evacuated. Optionally, the substrate can be heated or cooled, for
example, with
gas introduced into the chamber or by heat transfer fluid flowing through the
substrate
mounting structure. If a gas is introduced, care should be taken that it will
not alter the
substrate in an unintended manner, such as by oxidation of a hot iron-
containing surface by
an oxygen-containing gas. Introduced gas optionally can be evacuated once the
substrate
achieves the desired temperature. Vapor of one or more metal compounds, such
as
cerium(III) 2-hexanoate, enters the vacuum chamber and deposits on the
substrate. A
specific volume of a fluid composition containing the metal compound can
provide a specific
amount of compound to the surface of the substrate within the vacuum chamber,
depending
on the size of the chamber and other factors. Optionally, a chosen gas is
vented into the
chamber and fills the vacuum chamber to a chosen pressure, in one example,
equal to one
atmosphere. The chamber is heated to a temperature sufficient to convert at
least some of the
compounds into oxides, for example, 450 C, for a discrete amount of time
sufficient for the
conversion process, for example, thirty minutes. In this example, a ceria
layer forms on the
substrate. Optionally, the process can be repeated as many times as desired,
forming a
thicker coating of ceria on the substrate. In some embodiments, the component
can be cooled
relative to ambient temperature, such as, for example, to liquid nitrogen
temperature, to aid
the deposition process. In other embodiments, a reducing atmosphere may be
used to convert
at least a portion of the metal oxides to metal.
[00220] In other embodiments, the substrate can comprise one or more polymers,
such
as polyvinyl chloride. The polymer substrate can be kept at lower temperatures
sufficient to
prevent the degradation of the substrate during the heating process, for
example, at liquid
nitrogen temperatures while the metal compound converts to the oxide due to
any technique
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that heats the metal compound but not the substrate to a significant degree.
Examples of such
heating techniques include flash lamps, lasers, and microwave heating. In
addition, materials
that would become degraded by exposure to high temperatures can be kept at
lower
temperatures using the same techniques. For example, glasses, low-melting-
temperature
metals, polycarbonates, and similar substrates can be kept cooler while the at
least one metal
compound is converted to at least one metal oxide.
[00221] As used herein in reference to process gases used to carry out the
process of
the invention, the term "high temperature" means a temperature sufficiently
high to convert
the metal compound to metal oxide, generally in the range of about 200 C to
about 1000 C,
such as, for example, about 200 C to about 400 C, or about 400 C to about
500 C, about
500 C to about 650 C, about 650 C to about 800 C, or about 800 C to about
1000 C.
Process gases at even higher temperatures can be used, so that, when the gas
is passed
through the fluid transport or processing system during the process of some
embodiments of
the invention, the temperature of the gas exiting the system is within the
range given above.
[00222] A given embodiment of the invention described herein may involve one
or
more of several basic concepts. For example, one concept relates to a surface
treatment that
generally meets above-described technical properties and can be manufactured
at a low cost.
Another concept relates to a method to form an oxide protective film on the
surface of a
metal. Another concept relates to a two-step process adapted to form a
prophylactic layer
onto internal surfaces of a fluid transport or processing system. Another
concept relates to
creating thin films of nanocrystalline zirconia on surfaces to resist fibrous
growth of carbon
and other elements. Another concept is related to a means to apply a
protective coating to an
assembly of various components using a process to heat an enclosed system as a
curing
method for the coating.
[00223] In some embodiments of the invention, an oxidizing coating may be
formed
on a substrate by applying a liquid metal compound composition to the
substrate using a
dipping process, spraying, vapor deposition, swabbing, brushing, or other
known means of
applying a liquid to an internal surface of a pipe, conduit or process
equipment. This liquid
metal compound composition comprises at least one rare earth metal salt of a
carboxylic acid
and at least one transition metal salt of a carboxylic acid, in a solvent, in
some embodiments.
The surface, once wetted with the composition is then exposed to a heated
environment that
will convert at least some of the metal compounds to metal oxides, thereby
forming an
oxidizing coating on the substrate.
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[00224] The metal oxide coatings resulting from the conversion process, such
as thin
films of nano crystalline materials, are applied to material substrates to
form one or more thin
protective layers. Additional applications of the metal compounds followed by
conversion
environment exposure (e.g., heating the surface through means described above)
may be done
to create multiple layers of thin film oxides stacked one on another.
[00225] The process may be used to create a nanocrystalline structure that
comprises
an oxygen containing molecule for chosen applications. Alternately, the
resulting
nanocrystalline structure may comprise a metal containing compound, a metal, a
ceramic, or
a cermet.
[00226] One benefit to some embodiments of the invention is the ability to
apply the
metal compound composition to an assembled system and then to flush high
temperature
gases through the system to achieve the conversion process, resulting in a
well-dispersed
metal oxide coating on all interior surfaces. This is especially beneficial
for welded piping
systems, heat exchangers, and similar components which use welding for their
assembly, said
welding typically destroying whatever surface treatments were applied to the
pipes, heat
exchangers, or other parts prior to welding. The high temperature conditions
of the welding
process tend to destroy all protective coatings. The invention provides a way
to create a final
metal oxide coating covering all parts of the process system, creating a
protective coating for
weld joints and component interiors alike.
[00227] To create a less porous thin film, for some embodiments, material may
be
added to the base fluid to act as filler material. In this way, the porosity
of the finished
coating is altered through the inclusion of nanoparticles of chosen elements
in the liquid
metal compound composition prior to the exposure of the composition to an
environment that
will convert at least a portion of the metal compound(s) into metal oxides.
The result is a
more dense thin film.
[00228] In some applications, where it is desirable to reduce a metal oxide to
a pure
metal, the treated substrate may be exposed to a reducing agent, such as
hydrogen or other
known reducing agent using known means for oxide reduction. For example, 7 %
hydrogen
in argon heated to 350 C can be used to form platinum in certain embodiments.
Other
metals that may be desired, such as for catalytic purposes, for example,
include but are not
limited to platinum, palladium, rhodium, nickel, cerium, gold, silver, zinc,
lead, rhenium,
ruthenium, and combinations of two or more thereof.
[00229] As described above, the method of the invention may be used to provide
prophylactic coatings to internal surfaces of fluid transport or processing
systems, and has
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particular utility in the area of fluid transport or processing systems in the
petroleum and
natural gas industries, where carbon fouling, corrosion, and hydrogen
embrittlement are
particular problems in pipelines and processing equipment. For example,
coating with the
ceria, or yttria-stabilized zirconia, or a combination of ceria and zirconia
will significantly
reduce carbon fouling on steel surfaces exposed to petroleum or other
hydrocarbons at
temperatures of around 570 C, in effect providing protection against any
effective or
measurable carbon deposition. Uncoated steel surfaces exposed to similar
conditions become
sufficiently fouled with carbon as to require cleaning after about 18 months
of service.
Inhibition of carbon fouling occurs during exposure to petroleum or other
hydrocarbons at
temperatures as high as 900 C. Similar improvement in fouling will occur in
fluid processing
systems used to process natural gas.
[00230] In addition to protection against carbon fouling, the method of the
invention
provides protection against other fouling and corrosion problems often
encountered in
chemical or hydrocarbon processing operations in various embodiments. For
example, the
method of the invention provides a partial or full barrier against the
intrusion of hydrogen
into a metal substrate, reducing surface and substrate degradation through
this known
mechanism, in some embodiments. In particular, the method of the invention
provides an
effective barrier against corrosive attack in further embodiments. Because the
resulting
surface coating provides an effective barrier between the material of the
process equipment
(typically metal, such as iron or steel) and the environment (e.g., a crude
oil, cracked
hydrocarbon, or natural gas stream), electrochemical and other reactions
between the metal
and the process stream are effectively reduced or prevented in still other
embodiments. This
is particularly important for stainless steel piping systems, where the high
temperatures
involved in welding of the steel causes chromium (the primary passivating
element in
stainless steel) to migrate to grain boundaries, creating a galvanic couple
between high Cr
and low Cr areas, which can lead to corrosive attack. Because the method of
the invention
allows application of the coating after the welds have been formed (and any
high temperature
damage has occurred) in some embodiments, areas of the system adjacent to the
weld are
insulated from exposure to the potentially corrosive environment of the fluid
being processed.
[00231] Exposure to certain types of welding, galvanic corrosion, and more
importantly hydrogen sulfide (often found in petroleum and natural gas process
streams) can
introduce hydrogen into the crystal lattice of the metal process equipment,
leading to
embrittlement and cracking. The method of the invention, by preventing
exposure of the
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metal to any hydrogen or hydrogen sulfide contained in the process stream, can
reduce or
eliminate this form of attack in certain embodiments of the present invention.
[00232] Other systems can be protected from various forms of fouling as well.
The
heat exchangers that can be protected according to various embodiments of the
present
invention include any kind of heat exchanger. Known heat exchangers pass
thermal energy,
whether for heating or cooling purposes, for example, between gases, between a
gas and a
liquid, between liquids, between a liquid and a solid, and between a gas and a
solid. Heat
exchangers for two-phased, semi-solid, paste and slurry systems are also
known. Heat
exchangers include, for example, oil refinery heating units, cooling towers,
automobile
radiators, HVAC systems such as air conditioners, solar towers, geothermal
harvesters,
refrigeration units, and the like.
[00233] The materials that can be protected from fouling according to the
present
invention include any material that can receive a protective coating of a
metal oxide. Such
materials include, for example, metals, ceramics, glasses, and cermets, as
well as composites
and polymers that can withstand the process conditions for converting the
metal carboxylate
into metal oxide. The metals that can be protected include, but are not
limited to,
substantially pure metals, alloys, and steels, such as, for example, low alloy
steels, carbon
steels, stainless steels, 300 series stainless steel, 400 series stainless
steel, nickel base alloys,
high-chromium steels, and high-molybdenum steels.
[00234] The industrial and commercial products that can be protected according
to the
present invention are not limited. Petroleum refinery; petrochemical
processing; petroleum
transport and storage such as pipelines, oil tankers, fuel transport vehicles,
and gas station
fuel tanks and pumps; sensors; industrial chemical manufacture, storage, and
transportation;
automotive fluid systems including fuel systems, lubrication systems,
radiators, air heaters
and coolers, break systems, power steering, transmissions, and similar
hydraulics systems;
aeronautical and aerospace fluid storage and transport systems including fuel
systems and
hydraulic systems; and food and dairy processing systems; combustion engines,
turbine
engines, and rocket engines; among many others, can benefit from the present
invention.
EXAMPLES
Example 1
[00235] Five 2" x 2" coupons of mirror-finish SS304 steel (McMaster-Carr) were
individually designated "Uncoated," "Zircon," "Glass," "YSZ," and "Clay."
Those
compositions mimic chemically and thermally inert materials by the same names
known in
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nature and industry, in an inventive manner. A wide range of similar materials
can suggest
additional compositions to be used as embodiments of the present invention.
The "Uncoated"
coupon was given no coating, to function as the control. Each of the other
coupons were
coated on one side with the following compositions in accordance with
embodiments of the
present invention:
Zircon: Zirconium 2-ethylhexanoate (28 % wt. of the final composition, Alfa-
Aesar), silicon
2-ethylhexanoate (33.5 % wt., Alfa-Aesar) and chromium 2-ethylhexanoate (1 %
wt., Alfa-
Aesar) were mixed into 2-ethylhexanoic acid (37.5 % wt., Alfa-Aesar), and the
composition
was spin-coated onto the steel substrate.
Glass: Silicon 2-ethylhexanoate (74 % wt., Alfa-Aesar), sodium 2-
ethylhexanoate (5.2 %
wt., Alfa-Aesar), calcium 2-ethylhexanoate (11 % wt., Alfa-Aesar), and
chromium 2-
ethylhexanoate (1.4 % wt., Alfa-Aesar) were mixed into 2-ethylhexanoic acid
(8.4 % wt.,
Alfa-Aesar), and the composition was spin-coated onto the steel substrate.
YSZ: Yttrium 2-ethylhexanoate powder (2.4 % wt., Alfa-Aesar) was dissolved
into 2-
ethylhexanoic acid (60 % wt., Alfa-Aesar) with stirring at 75-80 C for one
hour. Once the
composition was cooled to room temperature, zirconium 2-ethylhexanoate (36.6 %
wt., Alfa-
Aesar) and chromium 2-ethylhexanoate (1 % wt., Alfa-Aesar) were mixed in. The
composition was spin-coated onto the steel substrate.
Clay: Aluminum 2-ethylhexanoate (15 % wt., Alfa-Aesar), silicon 2-
ethylhexanoate (45 %
wt., Alfa-Aesar), and chromium 2-ethylhexanoate (2 % wt., Alfa-Aesar) were
mixed into 2-
ethylhexanoic acid. This composition was handbrushed onto the substrate, due
to the
viscosity of the composition. The composition apparently reacted with moisture
in the air
and began to solidify, making application difficult.
[00236] The coated steel coupons were placed in a vacuum oven, and evacuated
to
about 20-60 millitorr. The coupons were heated to 450 C, and then allowed to
cool to room
temperature. The process of depositing and heating was repeated to apply eight
coatings of
the appropriate composition on each coupon.
[00237] Each coated coupon was assembled into a test cell having a glass
cylinder (1"
inner diameter x 1.125" tall) clamped to the coated portion of the coupon. A
rubber gasket
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formed a seal between the glass cylinder and the coupon. Aqua Regia was
prepared from
HNO3 (1 part, by vol., 70%, stock # 33260, Alfa-Aesar) and HCl (3 parts, by
vol., -37%,
stock # 33257, Alfa-Aesar), poured into the glass cylinder, and allowed to
contact the coupon
for one hour. Then, the coupon was removed, rinsed, and photographed. The
photographs of
the tested coupons appear in Figures 3-7.
[00238] Aqua Regia, so-called because it is known to dissolve noble metals
such as
gold and platinum, severely etched the Uncoated stainless steel coupon. See
Figure 3. The
Zircon coupon, in contrast, remains largely unetched, showing only small
spots. See Figure
4. The Glass coupon also remains largely unetched, showing feint scratch-like
features. See
Figure 5. The YSZ coupon shows significant etching. See Figure 6. The Clay
coupon also
shows etching, although less severe than the Uncoated coupon. See Figure 7.
[00239] On a scale of 0-10, with 0 representing severe etching and 10
representing
complete protection, the coatings exhibited the following performance:
Coupon Performance
Uncoated 0
Zircon 8
Glass 7-8
YSZ 0-1
Clay 0-1
[00240] Observation of the Zircon and Glass coupons at magnifications of 100x
to
1,000x before exposure to Aqua Regia revealed uniform, non-porous, mostly
amorphous
coatings. Observation of the YSZ coupon at those same magnifications revealed
a surface
coating having a crystalline structure. Observation of the Clay coupon
revealed uneven
coverage, likely due to the humidity-catalyzed reaction and premature
solidification.
Preparation and application of the Clay composition in a moisture and/or
oxygen-free
environment may improve the Clay coating's characteristics and performance.
[00241] These results demonstrate protection of a steel substrate in a highly-
corrosive
environment by coatings prepared in accordance with the present invention.
These results
also demonstrate easy experiments for testing metal oxide coatings to assess
how they might
perform in a given environment.
[00242] Similar experiments can be done in other environments to determine how
metal oxide coatings might perform in those environments. The skilled artisan
will recognize
that compositions that did not perform well against Aqua Regia may perform
well in other
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environments. For example, it is believed that the YSZ coating reduces or
prevents coke
buildup. Furthermore, a composition's performance depends in part on the
application and
conversion conditions. For example, the Clay composition is expected to
perform well if it is
applied and converted in a suitable environment, as discussed above.
Example 2
[00243] Figure 8 shows a TEM micrograph at approximately two million x
magnification of a stainless steel SS304 substrate (104) having eight coats of
an
yttria/zirconia composition (102). The figure illustrates a diffused coating,
labeled Oxide-To-
Substrate Interlayer (106). In this example, the diffused coating is about 10
nm thick. The
TEM also shows crystal planes, indicating the nanocrystalline nature of the
yttria/zirconia.
Example 3
[00244] The interior oil-contacting surfaces of a boiler for a petroleum
fractional
distillation column are cleaned and then wetted with a well-stirred room
temperature
composition containing cerium(III) 2-ethylhexanoate (203 g; all weights are
per kilogram of
final composition), chromium(III) acetylacetonate (10.1 g), and cerium(IV)
oxide
nanoparticles (10.0 g, 10-20 nm, Aldrich) in 2-ethylhexanoic acid (777 g). The
composition
is applied to the boiler tubes by inserting a first pig into the boiler tube,
adding an aliquot of
the composition to the tube, and placing a second pig so that the first pig
and second pig
substantially contain the aliquot. Then, compressed nitrogen is introduced
behind the second
pig and the pressure is increased above 1 atm until the pigging package moves.
A steady
pressure is maintained until the pigging package emerges out the other side of
the boiler, and
the interior surface of the tube is wetted with the composition. Steam at 500
C heats the
boiler in the usual manner for 30 minutes, and then the boiler is allowed to
cool. A
substantially non-porous cerium oxide coating stabilized by chromium oxide
forms on the
oil-contacting surfaces of the boiler.
Example 4
[00245] Under an ethanol-saturated nitrogen atmosphere, the cleaned milk-
contacting
surfaces of a milk pasteurizer are wetted with a well-stirred composition
containing
titanium(IV) ethoxide in ethanol (500 g, 20 % Ti, Aldrich) and dry ethanol
(500 g), using a
pig as shown in Figure 1. After the pig is removed from the pasteurizer, dry
nitrogen heated
to 450 C flushes through the pasteurizer for fifteen minutes, and the
pasteurizer is allowed to
cool under a flow of room-temperature nitrogen. Analysis will reveal a
titanium dioxide
coating on the milk-contacting surfaces of the pasteurizer.
Example 5
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[00246] A clean automobile exhaust manifold is dipped in a stirred bath
containing a
first composition that contains zirconium(IV) 2,2,6,6-tetramethyl-3,5-
heptanedionate (459 g),
yttrium(III) 2,2,6,6-tetramethyl-3,5-heptanedionate (72.9 g), and hexanes (to
1 kg) so the
composition contacts interior and exterior surfaces. Optionally, openings can
be plugged so
the first composition does not contact the interior surfaces. The manifold is
removed from
the composition, suspended, and rotated to allow excess composition to drip
into the bath.
Microwave radiation irradiates exterior surfaces for ten minutes, and an
yttria-stabilized
zirconia coating forms on the exterior of the manifold. The exhaust-contacting
surfaces of
the manifold are flushed with a second composition containing zirconium(IV)
2,2,6,6-
tetramethyl-3,5-heptanedionate (459 g), yttrium(III) 2,2,6,6-tetramethyl-3,5-
heptanedionate
(72.9 g), platinum(II) acetylacetonate (1.01 g), and hexanes (to 1 kg), and
the composition is
drained from the manifold. Argon gas heated to 450 C is passed through the
interior of the
manifold for 30 minutes. Then, argon gas containing 7 % hydrogen heated to 350
C passes
through the interior of the manifold for 30 minutes. An yttria-stabilized
zirconia coating will
form on the interior surface of the manifold. The interior surface also will
contain platinum
metal sites to catalyze the oxidation of partially-combusted hydrocarbon fuel.
Moreover, an
yttria-stabilized zirconia coating will form to protect the exterior of the
manifold from
corrosion. Optionally, the manifold can be cooled to room temperature and then
slowly
lowered into a liquid nitrogen bath for a time.
Example 6
[00247] The interior surface of pipes of a used delayed coker were cleaned and
coated
as follows. A mechanical pig was passed through the pipes, propelled by water,
to scrape
carbon residue from the insides of the pipes. An air compressor equipped with
an air drier
blew dry air through the wet pipes overnight at a pressure of about 150 psi
and a volume of
about 160 standard cubic feet per minute (cfm). Then nitrogen gas was
introduced to the
pipes, and the coker was heated gradually to 750-800 F to further dry the
pipes, and then
allowed to cool gradually.
[00248] Two-pound open cell polyethylene sponges having a diameter of 8.5" to
14"
were squeezed by hand (with protective glove) and submerged in a composition
comprising
zirconium (IV) 2-ethylhexanoate (85 mol %) and cerium (III) 2-ethylhexanoate
(15 mol %),
and allowed to absorb the composition. Based on the estimation that one liter
of composition
coats approximately 200 m2 of interior pipe surface, the volume of the
composition was
measured before and after the sponge contacted the composition. A soaked
sponge was then
introduced into a 3" diameter pig launcher, which was connected by a flange to
the pipes to
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be treated at the process effluent side. The pipes to be treated contained
variable inner
diameters ranging from 3" to 4", and also included "mule ears," 90
intersections of one pipe
entering another. Mule ears provide a particular challenge to certain rigid
body pigs,
rendering some systems very difficult to send a pig through. At the opposite
end of the pipe
(process influent), a receiving pig launcher was attached, and a hose was
arranged to pass any
fluid effluent (gas and/or liquid) through a water trap which vented to
atmosphere. The pig
launcher with the soaked sponge was sealed, and compressed air from a
compressor capable
of 160 to 1600 cfm volume and 60 to 150 psi pressure drove the soaked sponge
from the pig
launcher, through the pipes, and into the receiving pig launcher, at a
velocity ranging from 20
to 125 feet per second. After the sponge was recovered, the pipe was sealed
and purged with
nitrogen gas. The coker burners were turned on one-by-one as is customary for
the coker to
avoid heating the pipes too quickly, at a maximum heating rate of 250 F per
hour to 820 to
1100 F maximum temperature. Then the burners were turned off one-by-one to
cool the
coker slowly to protect the pipes, again in the customary way. When the pipes
cooled to
below 250 F, another sponge soaked with coating composition was passed
through the pipes
in the same manner, followed by a nitrogen purge, heating, and cooling. Each
recovered
sponge was observed for wetness, damage, and cleanliness, indicating the pipe
was being
thoroughly wetted and cleaned further as the sponge passed through. A total of
six coats
were applied.
[00249] As previously stated, detailed embodiments of the present invention
are
disclosed herein; however, it is to be understood that the disclosed
embodiments are merely
exemplary of the invention that may be embodied in various forms. It will be
appreciated that
many modifications and other variations that will be appreciated by those
skilled in the art are
within the intended scope of this invention as claimed below without departing
from the
teachings, spirit, and intended scope of the invention. Furthermore, the
foregoing description
of various embodiments does not necessarily imply exclusion. For example,
"some"
embodiments may include all or part of "other" and "further" embodiments
within the scope
of this invention. In addition, "a" can mean "one and more than one;" it does
not mean "one
and only one" to the exclusion of duplicate or additional items.
