Note: Descriptions are shown in the official language in which they were submitted.
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ADDITIVE FOR LIQUID OR LIQUIFIED HYDROCARBON FUELED
DIRECT FIRED BURNERS, OPEN FLAMES AND RELATED PROCESSES
Related Applications
[0001] This patent application claims priority to U.S. Provisional Patent
Application
Serial No.60/613,699 filed on September 28, 2004, which is incorporated by
reference in its entirety.
Technical Field of the Invention
[0002] The present invention relates to the field of fuel additives, in
particular, to an
additive for hydrocarbon fueled burners and flames to enhance efficiency
and/or
reduce undesirable emissions, such as pollutants.
Background of the Invention
[0003] Many hydrocarbon f-uels have been used, each with their own advantages
and
drawbacks. Examples of such fuels include diesel, kerosene, heavy distillates
and
bunker fuels. Chemical compounds have been used as combustion improvers to
enhance combustion efficiency, of these types of fuels. Many of these
additives
contain metallic elements such as manganese, iron, copper, cerium, calcium and
barium. Each of these elements has advantages and disadvantages in particular
applications. Drawbacks of certain iron compounds include limited solubility
in fitels,
toxicity, and expense as an additive. Iuteraction with sulfur and creation of
sulfide
precipitate may also occur, which is undesirable.
[0004] In addition to the goal of improved combustion efficiency, smoke
emissions
reduction is also a concern, particularly for heavier fuels in direct fired
applications.
The industry has not made substantial progress on development of a fuel
additive for
reducing smoke and particulate emissions in these applications.
[0005] A fuel additive that includes a combustion catalyst to reduce smoke and
particulate emissions from open flame burners and other direct-fired
applications
would be advantageous. A fuel additive that increases efficiency and/or
decreases
pollutants for diesel and heavier fuels used in these applications would be
particularly
advantageous. It would also be advantageous to reduce smoke, particulate and
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nitrogen emissions from fuel applications. In addition to reduction of NO,
reduction
or elimination of HCN emissions is highly desirable.
[0006] An additive that does not result in the formation of precipitates and
burns
clean during the combustion process would be desirable.
Suinmary of the Invention
[0007] The present invention includes a fuel additive and a method of using
the
additive in relation to hydrocarbon fuel.
[0008] The fuel additive of the invention includes a phosphorus-containing
parent
solution containing [Y]XH2PO4, [Y],,+IHPO4,where Y is a cation. Y does not
have to be
the same cation in both salt compounds. The cationic portion of the salt
components
can be any cation, with potassium being a preferred cation. In this case, the
preferred
coinponents would be KH2PO4, KZHP04. These salts are at least partially
dispersed
and/or dissolved in water or other appropriate solvent to create the
pliosphorus-
containing parent solution. Advantageously, this embodiment of the fuel
additive is
an armnonia-free solution. One preferred einbodiment includes adding these
components, in the presence of water, to create the phosphorus-containing
parent
solution as an aqueous parent solution. The water acts as the solvent. Other
preferred
parent solution solvents include alcohols. Another group of preferred cations
would
be the allcali metals or Group 1A elements. While NH4 used as Y creates a fuel
additive that enhances fuel performance, there are instances when it is
preferred to
avoid ammonium and thereby ammonia altogether.
[0009] The phosphorus-containing parent solution is added or mixed with a
dispersion
fluid. The dispersion fluid is a fluid that is operable to maintain the salts
within the
dispersion fluid in at least a partially dispersed state and that is miscible,
or capable of
being maintained in solution, in the hydrocarbon fuel. In a preferred
embodiment, the
solvent is largely removed from the phosphorus-containing parent solution in
the
dispersion fluid through thermal means to create the fuel additive. The fuel
additive
is operable to enhance combustion when placed into contact with fuel in a
direct fired
burner or open flame and combusted. Enhanced combustion means that fuel
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efficiency is increased when compared to fuel without the fuel additive, or
that
pollutant output in an exhaust gas from the combustion is decreased or a
combination
of these effects. Typical pollutants can include NOx, HCN, SO2 particulate
matter,
carbon monoxide and other recognized pollutants resulting from the combustion
of
hydrocarbon fuel. It is noted that different geographical areas focus on
minimizing a
particular pollutant depending on air characteristics. Reduction of a target
pollutant
or a combination of pollutants, such as NOx and HCN is highly advantageous.
Alternately, increased fuel efficiency results in a total lower volume of
pollutants, as
well as economic advantage.
[0010] Another preferred embodiment of the phosphorus-containing parent
solution
includes the addition of [NH4]2HPO4 to the [Y]XH2PO4, [Y]X+HPO4, and water.
Yet
another embodiment includes the addition of NH4C2H302 wliere C2H302 ion is an
acetate group such that the solution contains [Y],tH2PO4, [Y]X+HPO4,
[NH4]2HP04,
NH4C2H302 and water. When the fuel additive is prepared using ammonium
compounds, ammonium compounds being defined as those compounds containing
NH,, groups, the nitrogen in the solution is essentially all in the form of
anunonium
ions. There is at most a negligible amount of free ammonia. In a preferred
embodiment, the solution has a pH between about 6.0 and 8Ø
[0011] Another preferred embodiment of the phosphorus-containing parent
solution
includes the addition of [Y] XPO4 to the [Y],,H2PO4, and [Y],+HPO4.
[0012] While orthophosphoric acids have been described, also called phosphoric
acids, this includes pyrophosphoric acids, which are the condensed analogs of
orthophosphoric acid. The difference being that, through the process to
condense the
orthophosphoric acid, the P043- becomes P2072- or other condensed phosphates.
Therefore, [Y],tH2PO4, and [Y],,+HPO4 are precursors to pyrophosphoric acids.
The
use of the pyrophosphoric and other condensed forms is therefore encompassed
within the definition of the orthophosphate form.
[0013] The phosphorus-containing parent solution of one embodiment of the
invention can be used in any type of enviromnent, either hydrophilic or
hydrophobic
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environments. In the case of a hydrophobic environment, it may be necessary
that a
carrier fluid or fluids be selected to allow for proper dispersion. A
dispersant used in
conjunction with the carrier fluids to create the fuel additive is also
encompassed in a
preferred embodiment. For liquid hydrocarbon fuel applications, at least one
carrier
fluid can preferably be a fluid with a least some hydrophilic character that
is miscible
with the fuel to act as compatibilizing agent in conjunction with dispersant..
[0014] The fuel additive of the invention is useful to enhance combustion such
that
more complete combustion is achieved with increased combustion to CO2 and H20
as
compared to the combustion of the fuel without the fuel additive. The outcome
is the
reduction of products of partial combustion as well as NOX and S02, thereby
increasing fuel efficiency.
[0015] The fuel additive is used by adding this additive to the fuel in an
amount
sufficient to increase fuel efficiency or to reduce pollutants. The terms
enhanced and
enhanced combustion refer to eitller of these effects. An example of reduced
pollutants is a reduction of NOx and HCN in an exhaust gas produced from a
direct
fired burner or open flame. Advantageously, both of these effects are observed
though the addition of the fuel additive of the current invention. A preferred
embodiment includes the addition of between about 50 and 150 ppm phosphorus
into
the fuel though the addition of the fuel additive. Increased amounts of
phosphorus are
effective as well. It is notable that a very cost-effective solution can be
prepared with
low weight percent of phosphorus. Another preferred target is around 1 ppm
phosphorus to 150 ppm phosphorus. Positive test results have been generated as
low
as 0.25 ppm phosphorus.
[0016] Included in the invention is a process for enhancing fuel performance
of a
hydrocarbon fuel in a combustion system including the steps of providing the
fuel
additive described above in an amount effective to enhance fuel performance to
the
hydrocarbon fiiel and combusting the hydrocarbon fuel with the fuel additive.
The
combustion system can be any means known to those with ordinary skill in the
art for
combusting hydrocarbon. The combustion system can include one or more direct
fired burners or open flames. In a preferred embodiment, this process is used
with a
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liquid or liquefied hydrocarbon fuel. The result of adding the additive to the
hydrocarbon fuel is an enhanced fuel that has a substantial amount of
hydrocarbon
fuel suitable for combustion, and an amount of the fuel additive operable to
enhance
combustion. Preferably, the enhanced fuel contains phosphorus in 'an amount
operable to reduce emissions upon combustion of the enhanced fuel as compared
to
the combustion of the hydrocarbon fuel without the fuel additive. More
preferably, the
enhanced fuel contains phosphorus of between about 1 and 150 ppm by weight.
[0017] An alternate embodiment of the invention includes a process for
enhancing
fuel performance of a hydrocarbon fuel in a combustion system including the
steps of
adding a chemical addition composition to the hydrocarbon fuel in an amount
effective to enhance fuel performance. The chemical addition composition is
created
by creating an intermediate solution by (i) mixing in an aqueous medium a
source of
reactive NH2 groups with one of the following:
l. (a) an alkali metal hydroxide to raise the pH of the intermediate solution
above
12 to form an aqueous ammonium/alkali metal hydroxide; or
2. (b) a source of phosphoric acid to lower the pH of the intermediate
solution to
about 0 to form an acidic ammonium mixture.
3. The next step includes either combining the intermediate solution of step
(i.a.)
with the source of phosphoric acid; or the intermediate solution of (i.b.)
with the
hydroxide at a rate sufficient to create a highly exothermic reaction. This
results in
reactive NH2 groups being contained in solution during the formation of the
chemical
addition composition. This chemical addition composition is added to the
hydrocarbon fuel.
[0018] The parent solution, or the chemical addition composition of the
invention, can
be added into or include a combustion fuel. Again, it can be advantageous to
include
dispersants to promote dispersion in fuels that are hydrocarbon based.
Exemplary
fuels kerosene, diesel fuel and residual fuels.
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[0019] An enhanced fuel is created when a substantial amount of a fuel
suitable for
coinbustion is combined with an amount of the phosphorus-containing parent
solution
or the chemical addition composition sufficient to reduce emissions or to
increase
efficiency upon combustion of the enhanced fuel. In certain circumstances, the
dispersion fluid is a quantity of a target fluid, that is, a fluid that
contains the desired
fuel.
[0020] A composition of phosphoric acid, alkali metal hydroxide and a source
of
reactive NH2 groups has been explored in U.S. Patent No. 5,540,788 for the
creation
of a conversion surface, the disclosure of the patent being incorporated
herein by
reference. The current invention includes the use of the conversion surface
composition as a fuel additive. In one embodiment the fuel additive is
chemical
addition composition for the enhancement of hydrocarbon fuels where the
chemical
addition composition has the composition disclosed in U.S. Patent No.
5,540,788.
This embodiment is unique in the use of the source of reactive NH2 groups,
which can
be advantageous under certain circumstances. While the chemical composition
including reactive NH2 groups has certain advantages, it can result in the
presence of
free ammonia. Various other embodiments of the fuel additive of this invention
avoid
the production of free ammonia and the related issues.
Detailed Description
[0021] The fuel additive of the invention is believed to perform a gas phase
conversion of hydrocarbon fuels to achieve more complete combustion to CO2 and
H20 in the process. Preferably, the fuel additive is provided as a dispersion
in the
dispersion fluid. Preparation preferably includes forming the aqueous parent
solution
that is emulsified and then added into base oils. Dispersion can be aided
through the
use of emulsifiers and dispersants. In a preferred embodiment, a dispersant
with a
total base number of from 30 to 160 on an oil-free basis is used. Tests run
using
infrared and other testing techniques confirm the reduction of CO from the
offgas
from the combustion of hydrocarbon fuels with the fuel additive of the
invention.
[0022] U.S. Patent No. 5,540,788 (the Defalco patent) teaches a process for
creating
an iron-phosphorus surface through the formation of a conversion surface on
iron
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substrates by delivering a phosphatizing compound in a lubricating fluid. The
present
invention also includes the use of the composition of DeFalco as a fuel
additive for
introduction into a burner or open-flame. The composition includes a source of
phosphoric acid, an alkali metal hydroxide and a source of reactive NH2
groups.
Notably, the source of the reactive NH2 groups produces the reactive NH2
groups as
a result of the highly exothermic reaction that is described in the Defalco
patent.
Testing indicates that the same compounds that act as a source of reactive NH2
groups in the above reaction do not produce reactive NH2 groups under
different
physical conditions since they follow a different reaction path. This specific
chemistry results from the highly exothermic reaction described in the DeFalco
patent. It is also noted that the physical conditions of high pH results in
the
production of free ammonia.
[0023] Both the new composition disclosed herein and the previously described
composition of Defalco can be used to produce the enhanced fuel performance.
[0024] The invention includes the use of the fuel additive in the direct-fired
burners
and open flames. This is believed to be particularly valuable for burners
using heavy
fuels such as bunker fuels, including bunker C. Use in the burner or flame
appears to
provide combustion benefits allowing for a reduction in particulate and other
emissions.. The process of the invention is effective at the high temperatures
produced
as part of the combustion process such that the fuel additive is contained or
present in
the flame with the fuel. The fuel additive acts as a catalyst to enhance
combustion.
[0025] One example of a preferred formulation of the invention includes the
following ratios: 1.597 mols KH2PO4, 0.693 mol K2HPO~, 0.315 mol [NH~]2HP04
and water. The pH of the solution can be controlled through manipulation of
the
ratios of these components. By manipulating the ratios of the resulting H2P04
and
HPO42- ions, the solution can be created in a preferred pH range of about 6.0
to about
8Ø
[0026] In a preferred embodiment, KH2PO4, K2HPO4, [NH4]2HP04 and water are
created into the phosphorus containing parent solution that is added to a
dispersion
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fluid, such as a refined oil dispersion fluid, and mixed with dispersants.
Exemplary
dispersants include polyallsenyl succinimides such as Texaco TFA 4690C,
Oronite
ODA 78012 and Ethyl Hitec 646. It may also be advantageous to include certain
carrier fluids. Exemplary carrier fluids include polyoxpropylene monols, diols
and
polyols, polyoxybutylene monols, diols and polyols, particularly Bayer
Actaclear
ND 17. The phosphorus containing parent solution is added in at approximately
10
wt. % of the refined oil dispersion fluid. This is heated to drive off a
significant
amount of the solvent, in this case, water. The mixture can be described at
this point
as a colloid. When the resulting solution is mixed into the fuel, an effective
ainount
of the phosphorus in the solution can be dilute. One example of a preferred
embodiment is 0.3 wt% phosphorus in the solution. Upon addition to the fuel,
the
phosphorus content can be in the range of 5-100 ppb and still be effective.
Preferably, 1-250 ppm phosphorus is used in the fuel. Higher amounts are also
effective. More preferably, 1-150 ppm phosphorus by weight is in the fuel with
the
fuel additive.
[0027] An example of an alternate embodiment of the phosphorus-containing
parent
solution that is for use in fuel includes mixing about 2.6 molar (M)
orthophosphate
with alkali metal and ammonium cations, the resulting aqueous parent solution
having
a pH of 7 at ambient temperatures. A measured volume of this aqueous parent
solution is suspended in a mixture of refined oil dispersion fluid and
dispersant, most
of the water of the aqueous parent solution is removed thermally, and diluted
to about
0.3 weight % P. This mixture is used, with further dilution, as an additive to
fuels.
The dilution is preferably achieved with the same refined oil dispersion
fluid. A
Group II base oil is preferred. Other preferred dispersion fluids include
light
hydrocarbons, gasoline, polygas, kerosene, diesel, naphtha light oils, Group
I, III, IV,
V or VI base oils as defined by API, aromatic oils, polybutenes, polyglycols,
heavier
oils or combinations of the same. When added to f-uel, the aqueous parent
solution
prepared in this fashion acts to diminish the emission of pollutant molecules
under
normal operating conditions. An example of an alternate embodiment includes
the use
of phosphoric acid, potassium hydroxide, ammonium hydroxide in water. Acetic
acid
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can also be added. The amounts of the components can be adjusted to reach the
desired pH.
Example 1
1. Prepare a Phosphoric Acid1 Acetic Acid solution [H3PO4/HOA" Solution]. For
this run, the H3PO4/HOAc Solution is about 90% mole of H3PO4 and 10% mole of
HOAc.
2. Prepare for reaction De-ionized water
3. 2,736.391bs of the Potassium Hydroxide is added to the water
4. Add to this aqueous solution 1315.141bs of the Aminoniuin Hydroxide (29%)
5. Into the resulting solution, add the H3PO4/HOAc Solution and allow for
reaction.
6. After reaction, adjust pH with acetic acid to a pH of about 7Ø The
resulting
product of this reaction is useful as the chemical addition component to
enhance
liydrocarbon fuel.
Example 2
[0028] Laboratory tests with the fuel additive of KH2P04, K2HPO4, [NH4]2HPO4
in
refined oil dispersion fluid as an additive in diesel fuels show major
improvements in
fuel efficiency. Sodium has also been evaluated for use as a cation in this
formulation. Group IA metals are also preferred cations. Factors related to
selection
of the cation include commercial expense and corrosion resistance.
Example 3:
[0029] Use of the fuel additive described in Example 2 in combination with a
low
sulfur diesel fuel provided a 74% reduction in CO emissions in the exhaust gas
as
compared to diesel without the fuel additive, 34% reduction in S02, and 55%
reduction in particulates.
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Example 4:
[0030] Use of the fuel additive described above in combination with natural
gas
showed an 87% reduction in the formation of carbon monoxide as compared to
combustion of the natural gas without the fuel additive, and an 18% reduction
in NOx.
Example 5:
Unit Ratio
Component lbs weight
---------------------------- ----------- ----------
Phosphoric Acid 2,583 0.25
Potassium Hydroxide 2,736 0.26
Ammonium Hydroxide 1,315 0.13
Acetic Acid 672 0.06
Deionized Water 3,105 0.30
Total Phosphorus-Containing Parent Solution 10,411 1.00
Example 6:
Input Unit Ratio
Component Lbs weight
---------------------------- ----------- ----------
Star 4 Base Oil 8,544 0.79
Kerosene 1,282 0.12
ODA 78012 205 0.02
Hitec 646 205 0.02
Actaclear ND 17 85 0.01
Phosphorus-Containing Parent Solution (Example 5) 273 0.03
Total 10,748 1.00
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[0031] This is further diluted in base oil to adjust to desired concentration
of
phosphorus in fitel additive. The solvent is removed from the solution in
order to
create the fuel additive. In this case, the solvent is water and dehydration
is
accomplished thermally.
[0032] An alternate embodiment includes the use of [NH4]H2PO4, [NH4]2HP04 and
water. In a preferred embodiment, the solvent is one that is defined by
solubility or
dispersability of the salts in the solvent as well as the volatility of the
solvent. For
example, the salts are preferably dispersed throughout the solvent but the
solvent is of
such volatility that it can be boiled out of solution and preferably recovered
for reuse
without affecting the resulting product.
[0033] While the invention has been shown or described in only some of its
forms, it
should be apparent to those skilled in the art that it is not so limited, but
is susceptible
to various changes without departing from the scope of the invention. For
example,
introduction of the salts into the fuel or the dispersion fluid can be
accomplished
through high speed shear mixing without the creation of an intermediate
solution and
the subsequent thermal removal of the solvent. Regarding the salts, [Y]XHZPO4,
[Y]X+HPO4 also encompasses [Y]X[H2PO4]Z, [Y]X+[HPO4]Z where x and z are
variable
integers.
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