Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS AND APPARATUS FOR CONVERSION OF-ORGANIC, WASTE,
OR LOW-VALUE MATERIALS INTO USEFUL PRODUCTS
FIELD OF THE INVENTION
[0002] The present invention generally relates to the processing of waste or
low-value
products to form useful raw materials. More specifically, the invention
relates to a process and
apparatus for converting agricultural, and other waste or low-value materials
that contain carbon-
based compounds, to commercially useful products such as fuel oil, fertilizer
and specialty organic
chemicals. The present invention further relates to conversion of organic
materials into
hydrocarbons and carbon solids. In particular, the invention relates to an
apparatus that comprises
a heater, a reactor, a first cooler, and a second cooler, and a process for
using the same. The
present invention still further relates to separation of particulates from a
fluid suspension using a
separator that separates out particulates of a dimension of about 1 micron,
such as cellular debris
from bacteria, from a surrounding fluid.
BACKGROUND
[0003] It has long been recognized that many of the waste products generated
by human
society can, ultimately, be broken down into a small number of simple organic
materials that have
their own intrinsic value. If this transformation could be achieved in an
energy-efficient manner,
and on a large enough scale, then there could be enormous benefits to society.
[0004] Most living materials, as well as most synthetic organic substances
used in domestic
and commercial applications comprise carbon-based polymers of various
compositions. Under
appropriate conditions, most such materials - including wood, coal, plastics,
tires, and animal
waste - will break down to a mixture of gaseous products, oils, and carbon.
Materials such as
agricultural waste products may also contain inorganic substances that break
down to mineral
products. Almost all of these products, whether organic or inorganic, can
enjoy new lives in a
host of beneficial and often lucrative applications.
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[0005] Not only is the principle of creating useful materials from otherwise
unserviceable
waste appealing: recycling of waste materials is of fundamental importance to
the way that the
burgeoning human population will come to cope with major challenges in the
21St century. Two
principal challenges facing humanity are coping with a finite supply of
materials and energy, and
with curtailing the growing threat to the environment from global warming,
Indeed, an idea that is
rapidly gaining currency is that recycling carbon-based materials from within
the biosphere rather
than introducing new sources of carbon from underground oil, natural gas and
coal deposits could
mitigate global warning.
[0006] As of today, however, industries that produce huge volumes of waste
products
comprising largely organic materials face enormous challenges in disposing and
storing that
waste, as well as putting it to maximum beneficial use.
[0007] A case in point, the food processing industry around the world
generates billions of
pounds of organically rich wastes per year. These wastes are associated with
the processing of
both animal and plant products, and include turkey-, fish-, chicken-, pig-,
and cattle-processing
and husbandry wastes. The food processing industry continues to grow and its
members face
significant economic and environmental pressures to do something productive
with their waste
products. Such waste products give rise to a number of critical problems. The
generation of
greenhouse gases such as carbon dioxide and methane by landfilling, land
applying, or digesting
food wastes, without any other benefit, is one such problem. Ideally, the food
industry must adopt
efficient and economical ways of managing their wastes without discharging
odorous or
objectionable pollutants.
[0008] More recently, the cost of warehousing unusable byproducts in many
areas is growing
in significance. As the types of waste products that can be fed to
agricultural livestock become
increasingly regulated. For example, in the wake of BSE/CJD scares in Europe,
many waste
products are simply being warehoused, pending a suitable fate. Clearly, there
is an additional
urgent need to find an acceptable means to cleanly process and utilize such
materials. Preferably,
a way to convert food-processing wastes into useful, high-value products needs
to be found.
[0009] An additional drive to seek treatment alternatives is the combined
enforcement of
wastewater discharge regulations and the escalation of sewage surcharges. The
food processing
industry must seek cost-effective technologies to provide pretreatment or
complete treatment of
their wastewaters and solid (wet) wastes. Historically, food processing
facilities located within or
adjacent to municipalities, have relied on local publicly owned treatment
works (POTWs) for
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wastewater treatment and disposal. Increasingly, this option is becoming less
available, as a result
of more rigorous enforcement. Pressure to comply with wastewater discharge
permits has
increased. Dwindling federal grants for construction of new and upgraded POTWs
also mean that
this option is less appealing. Thus, the food-processing industry is
increasingly being pressured
with regard to how to effectively dispose of its inedible products.
[0010] Bioaccumulation of persistent chemicals such as dioxins and the
potential for the
spread of life threatening diseases such as Mad Cow Disease (BSE) is another
threat to food
processors and food consumers alike. This threat is greatly exacerbated by
refeeding food
processing residues to farm animals. Food processors need economical solutions
to break this
cycle.
[0011] Furthermore, municipal and regional sewer authorities are requiring
industries to
reduce their organic biochemical oxygen demand (BOD), chemical oxygen demand
(COD), and
solid loading on the sewers. Due to the high BOD concentrations typically
found in high-strength
food process wastewaters with high levels of suspended solids, ammonia, and
protein compounds,
the food processing industry is under additional scrutiny. Food processing
facilities need cost-
effective and application-specific treatment technologies to manage their
wastewaters and solid
wastes effectively.
[0012] Similar problems are multiplied, magnified and augmented in many
different ways
across other industries. For example, the generation of malodorous air
emissions associated with
rendering plants - that convert animal waste by heat into fats and proteins,
is one such problem.
Another is land application of municipal biosolids that contain high
concentrations of pathogens.
[0013] There have been various approaches developed to process used waste
tires, say from
truck and passenger vehicles, into useful products including fuels, petroleum
oils, carbon, fuel-
gases, and feedstocks for manufacture of tires and other rubber products.
Typically, these
schemes involve heating and dissolving the tires in solvents. Some of the
schemes attempt to
devulcanize the tire rubber, i.e., break the sulfur bonds that connect the
constituent polymers along
their lengths. Others attempt to depolymerize the rubber material.
Depolymerization breaks the
long chain polymers into shorter ones that are more fluid so can more easily
be used as a product
such as a fuel oil. Some schemes involve the use of water under conditions
near or above its
critical point (3,200 psi and -370 C) where water is a very good solvent for,
and reactant with,
the tire material. However, such schemes are energetically inefficient because
of the energy
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required to achieve super-critical conditions. Furthermore, processing at
super-critical conditions
also requires expensive super-alloy operating equipment.
[0014] A number of organic materials have also been investigated for
dissolving tire material
to form a heavy oil or a devulcanized rubber product. Generally, the existing
schemes that operate
at modest conditions (<200 psi) produce heavy, contaminated products, whereas
those that use
lighter solvents produce better products but must use a solvent that is
expensive, or that requires
high pressure (>2,000 psi), or both. Additionally, most schemes that use a
solvent to dissolve tire
material are uneconomical because some fraction of the solvent is lost during
the process and
there is a cost associated with the make-up solvent, even in instances where
solvent recovery and
reuse can be practiced.
[0015] Aerobic and anaerobic digesters have been employed at sewage treatment
plants to
treat municipal sewage sludge. There are a number of problems associated with
their use. The
basic principle behind their operation is that biologically rich materials are
directed into large
holding vessels that contain bacteria which digest the biological materials.
Typically, dissolved
solids are directed to an aerobic digester, and suspended solids are directed
to an anaerobic
digester. Once the nutritional feed materials are exhausted, the bugs can no
longer sustain
themselves, and they die. The end-product of the digestion period is a sludge
that contains the
dead bacteria, and which must be disposed of in some way. One problem with the
resulting
material is that it still contains pathogens. Problems with the whole process,
in general, include
that the holding times in the digester vessels can be as long as 17 days, and
that the operating
conditions are difficult to maintain. For example, the relatively large vessel
(typically 20-30 ft. in
diameter) is usually maintained at above 85 F, and in some cases above 122
F.
[0016] All of the disposal technologies currently available to industries, in
particular the food
processing industry, have significant limitations and drawbacks that provide
an incentive to search
for alternative processes. This applies to technologies in addition to the use
of existing POTWs.
In particular, four types of approach, land disposal (landfills, composting,
land application),
biotreatment, traditional thermal oxidation treatments such as
incineration/combustion, and
pyrolysis/gasification, all have separate drawbacks.
[0017] Drawbacks for land disposal include: high haulage or transport costs,
significant
potential for groundwater contamination from leaching, and the exposure of
area residents to high
concentrations of hazardous pollutants (such as pathogens in the instance of
land application).
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Landfills produce gas that can, create air pollution concerns, including the
generation of
greenhouse gases.
[0018] Disadvantages for biotreatment of waste include difficulty with
control, and inability to
verify performance because of the difficulty with verifying adequate airflow
into the soil. The
airflow must be maintained to provide oxygen if using aerobic bacteria. For
example, bacteria
that may have been developed to consume specific compounds will, when placed
in soil, activate
alternative enzyme systems to consume the easiest available compounds.
[0019] Drawbacks with older units that carry out incineration or combustion
include the
requirement to add equipment to meet air pollution emission standards that are
continually being
made more stringent by the government. It may also take longer to obtain air
discharge permits
for incinerators than for other technologies due to significant community
concerns about
incineration. Additionally, the treatment of the waste at the exhaust means
treating large volumes
of gas so that very large plant equipment is required. The feedstock is also
low in calorific value.
Some incinerators are not compatible with solid fuels or solid waste, as these
materials will start to
oxidize too high up in the furnace. Conversely, high moisture content in the
feedstocks is also a
problem because during incineration or combustion the water is vaporized and
removed - a
process which requires approximately 1,000 Btu/lb of water vaporized. This
represents huge
heat/energy losses to the system.
[0020] The last category of technique employed - pyrolysis/gasification - is
appealing
because, unlike the others mentioned, it attempts to convert the waste into
utilizable materials,
such as oils and carbon. Of principal concern when searching for optimum ways
of breaking
down waste products is how to adjust the composition of the resulting
materials while minimizing
the amount of energy needed to effect the breakdown. In the past, the
principal pyrolysis and
gasification methods that have been employed attempted to break down the waste
products in a
single stage process, but a single stage has been found to offer inadequate
control over purity and
composition of the end products.
[0021] Pyrolyzers have been used to break down organic materials to gas, oils
and tar, and
carbonaceous materials. A pyrolyzer permits heating of the organic materials
to high
temperatures, -400-500 C, but has poor energy efficiency and gives little
control over the
composition of the resulting materials. In particular, most waste products -
especially those from
the agricultural industry - contain up to 50% water. The pyrolyzer needs to
boil off that water, a
process that is very energetically demanding. Additionally, a pyrolysis
chamber tends to be large
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in order to maximize throughput, but then gives rise to significant
temperature gradients across the
chamber. Thus, the pyrolysis process involves an uneven heating of the waste
products and leads
to poor quality or impure tars and oils in the resulting end products.
[0022] Gasifiers have been used to achieve a partial combustion of waste
products. In
essence, a gas -usually air, oxygen, or steam - is passed over the waste
products in an amount that
is insufficient to oxidize all the combustible material. Thus, some combustion
products such as
CO2, H2O, CO, H2 and light hydrocarbons are produced, and the generated heat
converts the
remaining waste products into oils, gases, and carbonaceous material. The
gases produced will
contain some of the input gases, but any gases that are produced are too
voluminous to be stored
and must be used immediately or piped to a place where they can be utilized.
Gasifiers also suffer
from some of the same drawbacks as pyrolyzers: for example, a water-containing
waste product
will consume a lot of energy in vaporizing the water content.
[0023] Both pyrolysis and gasification methods additionally have the problem
that the
resulting materials contain unacceptable levels of impurities. In particular,
sulfur- and chlorine-
containing materials in the waste products give rise, respectively, to sulfur-
containing compounds
such as mercaptans, and organic chlorides in the resulting end products.
Typically, chlorinated
hydrocarbons at levels of 1-2 ppm can be tolerated in hydrocarbon oils, but
neither gasification
nor pyrolysis methods can guarantee such a low level with any reliability.
[0024] Furthermore, pyrolysis and gasification methods have low efficiencies,
typically
around 30%. One reason for this is that the products are not optimum in terms
of calorific
content. A further reason is that, in a single stage process, the materials
are not produced in a
form that easily permits their energy to be usefully re-used within the
process. For example, it is
difficult to capture the thermal energy in the solid products that are
produced and redirect it to
assist in the heating of the reaction vessel.
[0025] Overall, then, pyrolysis/gasification methods suffer in several ways.
The oil product is
generally rich in undesirable high viscosity components such as tar and
asphalt. Both pyrolysis
and gasification processes have poor heat transfer properties and consequently
do not heat evenly.
Therefore, end products vary greatly in number with few of sufficient quantity
or quality for
economical recovery. Wet feedstocks require significant energy to vaporize and
represent large
energy losses to the system since the water leaves as a gas in the stack.
Thus, in summary, the
disadvantages of pyrolysis/gasification are that the overall operating cost is
high, the process is
capital intensive and some by-products may have limited or no value.
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[0026] Although there have been many variants of the pyrolysis and
gasification methods, all
of which have suffered from broadly similar drawbacks, one recent advance has
permitted
significant increases in processing efficiency. For example, U.S. patent nos.
5,269,947,
5,360,553, and 5,543,061, disclose systems that replace the single-stage
process of the prior
methods with a two-stage process. In a first stage (often referred to as the
"wet" stage), the waste
products are subjected to heat at around 200-250 C and at about 20-120
atmospheres pressure.
In a preferred embodiment, the waste products are subjected to a pressure of
about 50
atmospheres. Under such conditions the water content of the waste material
hydrolyzes many of
the biopolymers such as fats and proteins that may be present to form a
mixture of oils. In a
second stage (often called the "dry" stage), the mixture is flashed down to
low pressure, during
which around half of the water is driven off as steam. The mixture is heated
still further to
evaporate off the remaining water while the mixture ultimately breaks down
into gaseous
products, oils, and carbon.
[0027] The principal advance of these two-stage methods was to permit
generation of higher
quality and more useful mixtures of oils than any of the previous single stage
processes.
However, the products of such methods still suffer from problems of
contamination, from
materials such as sulfur- and chlorine-containing compounds, and the need to
evaporate a
significant portion of the water still entails a substantial energy penalty.
Thus, prior two stage
methods have been difficult to make commercially viable.
[0028] Accordingly, there is a need for a method of processing waste and low-
value products
to produce useful materials in reliable purities and compositions, at
acceptable capital and
operational cost.
SUMMARY OF THE INVENTION
[0029] The present invention addresses the processing of waste and low-value
products to
produce useful materials in reliable purities and compositions, at acceptable
cost, without
producing malodorous emissions, and with high energy efficiency. In
particular, the invention
comprises a multi-stage process that converts various feedstocks that
otherwise have little
commercial value or use, to useful materials including gas, oil, specialty
chemicals (such as fatty
acids), fertilizer, and carbon solids. The invention further comprises an
apparatus for performing
a multi-stage process of converting waste products into useful materials, and
at least one oil
product that arises from the process. The apparatus and process of the present
invention are
particularly applicable to processing organic and inorganic waste, including
offal from poultry
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(such as turkey, chicken, ostrich), cattle, pigs, fish, and other waste
products such as animal
manures, grease, vegetable oil, and municipal sewage sludge, as well as tires
and plastics.
[0030] In overview, a process according to the present invention subjects a
suitably prepared
feedstock to heat and pressure, separates out various components of the
resulting feed, then further
applies heat and pressure, to one or more of those components. Various
materials that are
produced at different points in the process of the present invention may be
recycled and used to
play other roles within the process of the present invention.
[0031] The present invention includes a process for converting a feedstock
into at least one
useful material, comprising: preparing a slurry from the feedstock; reacting
the slurry in a first
reaction to produce a reacted feed comprising at least one reacted solid
product, at least one
reacted liquid product, and water; separating the at least one reacted solid
product, the water, and
the at least one reacted liquid product from the reacted feed; and converting
the at least one
reacted liquid product into at least one useful material in a second reaction.
[0032] The present invention additionally includes an apparatus for converting
a feedstock
into at least one useful material, comprising: a pre-treatment unit configured
to produce a heated
slurry from the feedstock; a first stage reactor communicating with the vessel
to receive the heated
slurry, the first stage reactor configured to subject the heated slurry to a
first increased temperature
and a first increased pressure to produce a reacted feed that comprises at
least one reacted solid
product, at least one reacted liquid product, and water; at least one
separation unit communicating
with the first stage reactor to receive the at least one solid product, at
least one liquid product, and
water, the unit configured to separate out the at least one reacted solid
product, the water, and the
at least one reacted liquid product; and a third stage reactor communicating
with the separation
unit to receive the at least one reacted liquid product, the third stage
reactor configured to subject
the at least one reacted liquid product to a second increased pressure and a
second increased
temperature, thereby converting the at least one reacted liquid product to at
least one useful
material. In a preferred embodiment, the pre-treatment unit comprises a
preparation unit,
including a slurrying device to create a feedstock slurry from the feedstock;
a vessel
communicating with the feedstock preparation unit to receive the feedstock
slurry from the
feedstock preparation unit, and additional equipment such as a pump and a heat
exchanger
configured to pressurize and heat the slurry to produce a heated slurry.
[0033] The present invention additionally includes a process for converting a
feedstock into at
least one useful material, comprising: preparing a slurry from the feedstock;
passing the slurry
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through a heat exchanger, wherein one or more gases is vented, to produce a
conditioned slurry;
reacting the conditioned slurry in a first reaction, wherein steam and gas is
liberated, to produce a
reacted feed comprising at least one reacted solid product, at least one
reacted liquid product, and
water, wherein the reacted solid product comprises at least one mineral;
lowering a temperature,
and lowering a pressure, of the reacted feed, to produce an intermediate feed;
separating the at
least one mineral from the intermediate feed, thereby producing a mixture
comprising at least one
reacted liquid product, and water; diverting said water to storage; subjecting
said at least one
reacted liquid product to a second reaction wherein carbon solids and a
mixture of hydrocarbon
vapor and gases are produced.
[0034] The present invention still further includes a process for converting
tires into oil,
comprising: dissolving the tires in a solvent; preparing a slurry from the
tires; reacting the slurry
with water in a first reaction to produce a reacted feed comprising at least
one reacted solid
product, at least one reacted liquid product; separating said at least one
reacted solid product, said
water, and said at least one reacted liquid product from said reacted feed;
converting said at least
one reacted liquid product into oil in a second reaction.
[0035] The present invention further includes a process for converting mixed
plastics into at
least one useful material, comprising: preparing a slurry from the mixed
plastics; reacting the
slurry with water in a first reaction to produce a reacted feed comprising at
least one reacted solid
product, at least one reacted liquid product; separating said at least one
reacted solid product, said
water, and said at least one reacted liquid product from said reacted feed;
converting said at least
one reacted liquid product into at least one useful material in a second
reaction.
[0036] The present invention additionally includes a process for converting
municipal sewage
sludge into at least one useful material, comprising: preparing a slurry from
the municipal sewage
sludge; reacting the slurry in a first reaction to produce a reacted feed
comprising at least one
reacted solid product, and at least one reacted liquid product, and water;
separating said at least
one reacted solid product, said water, and said at least one reacted liquid
product from said reacted
feed; converting said at least one reacted liquid product into at least one
useful material; and in a
second reaction, converting said at least one solid product into a mixture of
hydrocarbon oils, fuel
gas and a mixture of minerals and carbon.
[0037] The present invention also includes a process for converting turkey
offal into at least
one useful material, comprising: preparing a slurry from the turkey offal;
reacting the slurry in a
first reaction to produce a reacted feed comprising at least one reacted solid
product, and at least
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one reacted liquid product, and water; separating the at least one reacted
solid product, the water,
and the at least one reacted liquid product from the reacted feed; and in a
second reaction,
converting the at least one reacted liquid product into a mixture of
hydrocarbon oils, fuel gas, and
carbon.
[0033] The present invention further comprises a fuel oil manufactured by a
process, wherein
the process comprises: preparing a slurry from a carbon-containing feedstock;
reacting the slurry
in a first reaction to produce a reacted feed comprising at least one reacted
solid product, at least
one reacted liquid product, and water; separating said at least one reacted
solid product, said
water, and said at least one reacted liquid product from said reacted feed;
converting said at least
one reacted liquid product into the fuel oil in a second reaction.
[0039] The present invention additionally provides for an apparatus for
converting an organic
liquor into a mixture of hydrocarbons and carbon solids, comprising: a vessel
configured to
receive and heat the organic liquor to produce a mixture of liquid and
vaporized oil; a reactor
configured to receive and convert the mixture of liquid and vaporized oil into
carbon solids and a
mixture of hydrocarbons and gases; a first cooler for accepting the carbon
solids; and a second
cooler for accepting the mixture of hydrocarbons and gases.
[0040] The present invention further includes an apparatus comprising: a
heated vessel having
an inlet and an outlet; a first heated auger having an inlet and an outlet,
the inlet and outlet being
configured and dimensioned to permit higher pressure to be applied in the
first auger, the first
auger inlet communicating with the vessel outlet; a fluid-solid separator
communicating with the
first auger outlet, the separator having a first outlet for liquids and gases
and a second outlet for
solids; and a second auger communicating with the solids, the second auger
providing for cooling
of the solids.
[0041] The present invention still further includes a process for converting
an organic liquor
into a mixture of hydrocarbons and carbon solids, comprising: heating the
organic liquor to
produce a mixture of liquid and vaporized oil; converting the mixture of
liquid and vaporized oil
into carbon solids and a mixture of hydrocarbons and gases; and separating the
carbon solids from
the mixture of hydrocarbons and gases.
[0042] The process and apparatus of the present invention find application in
the processing of
waste and low-value products to produce useful materials in reliable purities
and compositions, at
acceptable cost, without producing malodorous emissions, and with high energy
efficiency. In
particular, the apparatus and process of the present invention may be used in
a multi-stage process
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that converts various feedstocks that otherwise have little commercial value
or use, to useful
materials including gas, oil, specialty chemicals (such as fatty acids),
fertilizer, and carbon solids.
The apparatus and process of the present invention are particularly applicable
to processing
organic and inorganic waste, including offal from poultry (such as turkey,
chicken, ostrich), cattle,
pigs, fish, and other waste products such as animal manures, grease, vegetable
oil, and municipal
sewage sludge, as well as tires and plastics.
[0043] The present invention also includes an apparatus for separating
particulates from a
fluid in a suspension, comprising: a housing defining a frusto-conically
shaped inner chamber
with an inner wall, an inlet and a first outlet communicating with the
chamber, and a second
outlet; and a spinning assembly with a hollow interior mounted in the chamber,
the assembly
being shaped to define an annular gap with the chamber inner wall, the hollow
interior
communicating with the second outlet, and the hollow interior communicating
with the annular
gap for flow of fluid materials from the gap into the interior and out of the
second outlet in
response to rotation of the spinning assembly. In an embodiment of the
apparatus for separating
particulates, the spinning assembly further comprises: a hollow spindle
defining a spindle inlet
and a spindle outlet, the spindle outlet communicating with the housing second
outlet; and a
tapered, porous cylindrical wall mounted on the hollow spindle to define the
hollow interior, the
hollow interior communicating with the hollow spindle through the spindle
inlet.
[0044] The present invention further includes an apparatus for separating
particulates from a
fluid in a suspension, comprising: a casing having an inner surface; a tapered
cylinder disposed in
the casing having a longitudinal axis, an angle of taper, and having a porous
wall with an outer
surface configured to form an annular gap between the outer surface and the
inner surface of said
casing, said tapered cylinder being concentrically mounted on a hollow spindle
so that it can be
caused to rotate about its longitudinal axis; an inlet for introducing the
suspension into the annular
gap at a flow rate; a first outlet in the casing for permitting separated
particulates to be released
from the device, upon rotation of the cylinder; and a second outlet in the
hollow spindle for
permitting fluid that passes through the porous wall to be drained from the
device, upon rotation
of the cylinder.
[0045] The separator of the present invention finds application in the
processing of waste and
low-value products to produce useful materials in reliable purities and
compositions, at acceptable
cost, without producing malodorous emissions, and with high energy efficiency.
The separator of
the present invention is particularly applicable to the preparation of organic
and inorganic waste
such as municipal sewage sludge for processing in a multi-stage process that
converts the sludge
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to useful materials including gas, oil, specialty chemicals (such as fatty
acids), fertilizer, and
carbon solids.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 shows a flow-chart of an overall process according to the
present invention;
[0047] FIG. 2 shows an apparatus for performing a process of the present
invention;
[0043] FIG. 3 shows a flow-chart of a preparation and first stage reaction of
a process of the
present invention;
[0049] FIG. 4 shows a flow-chart of a second, separation stage of a process of
the present
invention;
[0050] FIG. 5 shows a flow-chart of a third stage reaction of a process of the
present
invention;
[0051] FIG. 6 shows an apparatus for carrying out a third stage of the process
of the present
invention;
[0052] FIG. 7 shows an apparatus for separating fine suspended solids from a
fluid; and
[0053] FIGs. 8A and 8B show use, respectively, of a third stage reactor and a
cooler/condenser with a process according to the present invention.
DETAILED DESCRIPTION
[0054] The process of the present invention is directed to producing one or
more useful
materials from low-value or waste products generated by society at large,
either from ordinary
domestic practices, or from commercial operations. Typically the process of
the present invention
is applied to waste products, or other low-value products, for example grease,
that contain a
substantial proportion of organic materials. However, the present invention
may be applied to
convert other products, not normally considered low-value, to higher-value
products.
[0055] Organic materials are those commonly understood by one of ordinary
skill in the art.
In particular, for use with the present invention, organic materials are those
materials whose
constituent elements include carbon in combination with one or more other
elements such as
hydrogen, oxygen, nitrogen, sulfur, and phosphorous, and the halogen elements,
in particular
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fluorine, chlorine, bromine, and iodine. For the purposes of the present
invention, organic
materials also include compounds that contain carbon in combination with
elements such as
arsenic, selenium, and silicon, as well as salts of organic molecules, and
complexes of organic
molecules with metals such as, but not limited to, magnesium, mercury, iron,
zinc, chromium,
copper, lead, aluminum, and tin. Many organic materials used with the present
invention come
from biological sources and comprise proteins, lipids, starches, nucleic
acids, carbohydrates,
cellulose, lignin, and chitin, as well as whole cells. Other organic materials
for use with the
present invention, have man-made, or synthetic origin, such as plastics, and
other petroleum-
derived products.
[0056] In the process of the present invention, heat and pressure are applied
to a feedstock at
the levels needed to break the feedstock's long molecular chains. Thus,
feedstock material is
broken down at the molecular level to one or more constituent materials. In
the process, the
feedstock is transformed from a cost or low value to a profit, or significant
cost reduction, or
higher value. Importantly, the process is able to destroy pathogens.
[0057] The basic process of the present invention is designed to handle
potentially any waste
or low-value product, including: by-products of food manufacture and
distribution such as turkey
offal, fryer oils, corn stalks, rice hulls, waste scraps, last-press edible
oils such as canola, soybean,
palm, coconut, rape seed, cotton seed, corn, or olive oil, and other oils,
food processing wastes,
and seafood industry wastes; by-products of paper and other wood industry
manufacturing, such
as cellulose and lignin by-products, and paper-pulp effluent; yard waste such
as leaves and grass
clippings; tires; plastic bottles; harbor-dredged sediments; post-consumer
plastics and electronics,
such as old computers; municipal solid waste; oil-refinery residues;
industrial sludges; bagasse;
seaweed; milling waste; black liquor; coal refinery wastes; tar sands; shale
oil; drilling mud;
cotton waste; agricultural processing wastes such as animal manures;
infectious medical waste;
biological pathogens; and even materials such as anthrax spores that could be
used to make
biological weapons. It is to be understood that the foregoing list of
materials is not an exhaustive
list. In the foregoing list, bagasse is a byproduct from processing of sugar
cane, and black liquor
is a byproduct of chemical wood-pulping that results from dissolving wood
chips, liberating the
lignin, and freeing the fibers to give rise to a lignin and hemi cellulose
solution.
[0058] Waste products for use with the present invention are typically
byproducts or end-
products of other industrial processes, commercial preparations, and domestic
or municipal uses,
that typically have no other immediate use and/or which are ordinarily
disposed of. Low-value
products may similarly be byproducts or end-products of other industrial
processes, commercial
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preparations, and domestic or municipal uses, but are typically materials that
have very low re-
sale value and/or which require some further processing to be converted into
something of use.
[0059] When used with the process of the present invention, waste and low-
value products are
typically referred to as feedstocks or as raw feed. It is also to be
understood that the raw feed used
with the process of the present invention can comprise waste and/or low-value
products from a
number of sources, and of a number of different types. For example, food-
processing wastes
could be combined with agricultural processing wastes, if convenient, and
processed
simultaneously.
[0060] Still other exemplary raw feed materials for use with the present
invention include
municipal sewage sludge, mixed plastics (including polyvinylchloride ("PVC"))
as might be
obtained from a municipal recycling depot, and tires.
[0061] Polyvinyl chloride (PVC) is found in vinyl siding and plastic plumbing
pipes. PVC
contains about 55% by weight chlorine and thus has a propensity to give rise
to harmful chlorine-
containing compounds when degraded. For example, combusting PVC produces
dioxins, which
are some of the most toxic compounds known. One benefit of using water early
in the process of
the present invention is that the hydrogen ions in water combine with chloride
ions from the PVC
to yield solubilized products such as hydrochloric acid, a relatively benign
and industrially
valuable chemical which is useful for cleaners and solvents.
[0062] Tires are typically obtained from vehicles such as automobiles, buses,
trucks, aircraft,
and other mass-transit craft, as well as military and other commercial
vehicles. When applying
the process of the present invention to tires, a portion of the produced oil
is preferably recycled to
the inlet to assist dissolving the tires in the incoming feedstock.
[0063] Waste and low-value materials processed by embodiments of the present
invention are
generally converted into three types of useful materials, all of which are
both valuable and are not
intrinsically harmful to the environment: high-quality oil; clean-burning
gases; and purified solids
including minerals, and carbon solids that can be used as fuels, fertilizers
or raw materials for
manufacturing. Additionally, various side-streams are produced during the
process of the present
invention, including in some instances to concentrates similar to "fish
solubles." Typically, useful
materials are considered to be those that have a higher economic value than
the waste, low-value
or other materials that served as the feedstock. Such useful materials may
have, for example,
higher calorific content, or may have a wider range of applications than the
feedstock from which
they were derived.
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[0064] The process of the present invention comprises a number of stages, as
illustrated in
FIGs. 1 and 2. FIG. 1 shows, in outline, principal features of an embodiment
of the process of the
present invention. FIG. 2 shows an exemplary apparatus 200 for carrying out a
process according
to the present invention.
[0065] The raw feed 100, shown in FIG. 1, may potentially be any waste product
or low-value
organic and/or inorganic stream. Preferably, the raw feed contains a
substantial amount of carbon-
containing material.
[0066] Raw feed 100 is subjected to a preparation stage 110. An aspect of the
preparation
stage is to reduce the size of the raw feed using pulping and other grinding
technologies to a size
suitable for pumping. The preparation stage may comprise one or more steps,
and may comprise
adding materials to, or driving materials off from the raw feed, and results
in a slurry 112 that is
passed to a first stage 120. Slurrying may involve adding water (or other
suitable fluid) to raw
feed 100, depending upon its initial water content. Use of a slurry is
beneficial because wet
grinding, as in the preparation stage 110, reduces friction and energy
consumption, and because a
slurry may be easily transferred by pumps from one vessel to another. Suitable
slurrying devices
include: a pulper, an in-line grinder, or a maserator. A mixture of steam and
gases 121 is given
off from preparation stage 110.
[0067] In a first stage 120, the slurry is subjected to heat and increased
pressure wherein the
slurry undergoes a first reaction, also called a first stage reaction. Such
conditions of heat and
pressure lead to breakdown of the cell structure of biological components of
the slurry, to release
constituent molecules such as proteins, fats, nucleic acids, and
carbohydrates. Additionally, many
polymeric organic materials are hydrolyzed by water in the slurry to mixtures
of simpler organic
products. In particular, fats may be partially split to give floatable organic
materials such as fatty
acids (containing carboxylic acid groups), and water soluble glycerols (i.e.,
molecules containing
3 hydroxyl groups). Proteins are typically broken down into simpler
polypeptides, peptides, and
constituent amino acids. Carbohydrates are largely broken down into simpler,
water soluble,
sugars. Furthermore, the presence of water in the first stage is advantageous
because it helps
convey heat to the feedstock.
[0068] It is to be understood that the terms react, reacting and reaction,
when used in
conjunction with embodiments of the present invention, can encompass many
different types of
chemical changes. In particular, the term reaction can encompass a chemical
change arising from
the combination or association of two or more species that give rise to one or
more products, and
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can encompass other types of decompositions or conversions that involve the
breakdown or
transformation of a single species, as induced by conditions of temperature,
pressure, or impact of
electromagnetic radiation, and can further encompass transformations involving
a solvent, such as
a hydrolysis. It is further to be understood that when the term "reaction", or
"react" is used herein
to describe a process, or a stage in a process, then more than one chemical
change can be
occurring simultaneously. Thus, a reaction can simultaneously involve a
hydrolysis and a
decomposition, for example.
[0069] A mixture of steam and gaseous products 126 is typically liberated from
the slurry in
the first stage 120. The reacted feed 122 resulting from the first stage
typically consists of a
mixture of reacted solid products and a mixture of reacted liquid products.
These various products
are typically characterized as an oil phase, a water phase, and a wet mineral
phase. The water
phase and the oil phase typically contain various dissolved organic materials.
The mixture of
steam and gases 126 produced in the first stage 120 is preferably separated by
a condenser, and
the steam is used to pre-heat incoming slurry.
[0070] The reacted feed 122 is then subjected to a separation stage 130 in
which a further
mixture of steam and gases 132 is driven off, and a mixture of minerals 134 or
other solid
materials is separated out. Preferably, the solid materials obtained at this
stage do not comprise
carbon solids, unless carbon solid was present in the input feedstock.
Separation stage 130 may
comprise more than one individual separation.
[0071] The residual material from separation stage 130 consists of a mixture
of liquid products
that includes produced water 138 (water with solubles) and an organic liquor
500. The organic
liquor 500 is typically a liquid that contains a mixture of carbon-containing
species such as reacted
liquid products from the first reaction. Preferably, most of the produced
water 138 is separated
off, and a liquid product such as the organic liquor 500 is directed to a
third stage 140. Thus, the
organic liquor preferably comprises a reacted liquid product, separated from
water and in most
instances also separated from reacted solid product. The produced water 138
contains numerous
compounds including sulfur- and chlorine-containing materials and is
preferably diverted for
concentration 139. It is desirable to separate out such compounds and, in
preferred embodiments,
concentration gives rise to a condensate 151 (whose purity is usually better
than that of municipal-
strength wastewater), and a concentrate 153 (that, in many instances, can be
used as liquid
fertilizer similar to fish solubles).
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[0072] Some of organic liquor 500 may be diverted to an optional separation
137 to form
specialty organic chemicals 143 such as fatty acids or amino acids, for
example via fractional
distillation of the organic liquor. Residual fractions, fractionated liquor
145, often called `heavy
liquor', that comprises fractions that are not useful as specialty chemicals,
may be redirected to
third stage 140.
[0073] When the feedstock is municipal sewage sludge, the reacted feed 122
from the first
stage reaction typically comprises produced water, a solid matrix of organic
and inorganic
material, and a small amount of organic liquor. The produced water from
municipal sewage
sludge is then diverted for concentration to form a product that finds
application as a fertilizer.
[0074] In a third stage 140, the organic liquor 500 is subjected to conditions
wherein it
undergoes a second reaction. It is also possible that the organic liquor
contains some quantity of
reacted solid product that is also passed to the third stage. Together, the
organic liquor and
reacted solid product may be referred to as a solid matrix. In the second
reaction, the organic
liquor is converted to a mixture of useful materials that usually includes
carbon solids 142, and a
mixture of hydrocarbons that is typically released as hydrocarbon vapor and
gases 148. Such a
conversion may involve a decomposition of one or more materials in the organic
liquor. Suitable
conditions in the third stage typically use temperatures that are elevated
with respect to the first
stage, and use pressures that are reduced with respect to the first stage. The
third stage typically
does not involve the use of added water.
[0075] Carbon solids 142 are typically similar to coke, i.e., usually hard
carbonaceous
materials with a high calorific value suitable for use as a fuel. Carbon
solids 142 preferably
contain little, if any, non-combustible minerals that typically result from
the incineration of
carbon-containing materials in an oxygen-deficient atmosphere. The mineral
content of carbon
solids 142 is preferably less than 10% by weight, more preferably less than 5%
by weight, still
more preferably less than 2% by weight, and most preferably less than 1% by
weight. Where
carbon solids 142 contain minerals, they may also be described as a carbon-
mineral matrix.
[0076] The hydrocarbon vapor and gases 148 are referred to as "bio-derived
hydrocarbons"
whenever biological material is the feedstock to the process of the present
invention. The
hydrocarbon vapor and gases can be variously referred to as "tire-derived",
"rubber-derived" or
"plastic-derived" if the raw feed stock comprises tires, rubber, or plastics,
respectively.
Hydrocarbon vapor and gases 148 typically comprise hydrocarbon gases, with
possibly some trace
impurities of non-hydrocarbon gases. The hydrocarbon gases include gases such
as fuel-gas 146;
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the hydrocarbon vapors may be readily condensed to liquids or oils 144 such as
the lighter
constituents of #2 diesel oil. One of ordinary skill in the art understands
that a #2 diesel oil is an
oil with a relatively low viscosity or density.
[0077] When the feedstock is municipal sewage sludge, the solid products from
the third stage
typically comprise a mixture of hydrocarbon oils, fuel gas, and a mixture of
minerals with carbon,
in solid form.
[0078] It is to be understood that the operating parameters of the process of
the present
invention may be adjusted in one or more instances in order to accommodate
different types of
raw feed materials. For example, in the context of raw feed such as turkey
offal, the major
components are animal fats, proteins, carbohydrates, and minerals. Thus, the
balance of the major
components may determine some aspects of the operating conditions of the
present invention.
Furthermore, the temperature ranges of the first and third stage reactors can
be controlled to
produce specific products, thereby maximizing the economic value that can be
obtained from the
yield of various products.
[0079] An apparatus 200 for carrying out a process according to the present
invention is
shown in FIG. 2. Based on the teachings of the present invention, the assembly
of the various
components of apparatus 200 would be within the capability of one of ordinary
skill in the art of
process engineering or chemical engineering. Accordingly, such technical
details as would be
familiar to an artisan of ordinary skill are omitted from the present
description.
[0080] Feedstock preparation and slurrying may be carried out in a feedstock
preparation
apparatus 210. After feed preparation and feed slurrying, the slurry is passed
to a low pressure
vented vessel 220 referred to as a feed storage tank. Preferably the feed is
subjected to heating in
or before the feed storage tank to produce a heated slurry that is optionally
subjected to
pressurizing prior to entering the first stage reactor. Such heating and
pressurizing typically take
place in equipment that comprises a vessel to retain the slurry, a pump for
increasing the pressure
of the slurry, and a heat exchanger to heat the slurry. Typically conditions
of about 140 F and 1
PSI are employed, to keep the feed slurry in a liquid state, and to limit
biological activity. In a
preferred embodiment, the feed storage tank comprises a first tank and a
second tank. In such a
preferred embodiment, the first tank is heated to a temperature of about 140
F (about 60 C) and
subjected to a pressure of about 1 p.s.i. Such conditions in the first tank
effectively bring about a
cessation of biological activity. In an exemplary embodiment, such a first
tank may have a
capacity of about 1,000,000 U.S. gallons; thus, for a throughput of 100 - 150
gallons/minute, the
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effective residence time in such a tank is about 700 minutes. The second tank
in such an
embodiment may be maintained at a temperature of about 300 F and subjects the
contents to a
pressure of up to about 100 p.s.i. The pressure is generally slightly above
the saturation pressure
of the mixture at a given temperature. For example, the saturation pressure of
the mixture is 66
p.s.i. at about 300 F (about 150 C). The conditions in the second tank are
typically harsh
enough to breakdown proteinaceous materials in the slurry, to loosen the
slurry, and to drive off
ammonia. The capacity of the second tank is typically less than that of the
first tank, and may be
as small as 2,500 U.S. gallons. Thus, in one embodiment, a flow rate of about
40 gallons per
minute gives a residence time of about an hour in the second tank. Longer,
preferred residence
times for particular feedstocks, for example of several hours in the second
tank, may be achieved
with lower flow rates.
[0081] The first stage of the present invention is carried out in a first
stage reactor 230, which
preferably comprises a multi-chamber vessel so that there is a narrow
distribution of residence
times of the constituent materials of the slurry. In an alternate embodiment,
the first stage reactor
can also be an augured reactor. Preferably the vessel is equipped with
baffles, and a multi-blade
motorized stirrer that can simultaneously stir the slurry in each of the
chambers. In a preferred
embodiment, there are four chambers in such a vessel. In another preferred
embodiment, the
heating of the slurry takes place in several stages ahead of this vessel.
[0082] The flashing of the reacted feed after the first reaction can be
achieved in a flash vessel
240 (a "second stage separator") with a vent. Preferably the pressure in the
flash vessel 240 is
considerably lower than that in the first stage reactor 230. In one
embodiment, the pressure in the
flash vessel is about 300 psi, where the pressure in the first stage reactor
is around 600 psi.
[0083] Various equipment can be used to achieve various second stage
separations of the feed
that comes out of the first stage reactor 230. Preferably such separations
provide a mixture of
steam and gases 132, organic liquor 500, minerals 134, and produced water with
solubles 138.
Steam and gases 132 are preferably diverted back to the preparation stage to
assist with feed
heating.
[0084] Separation of the minerals from the organic liquor and water can be
achieved with
centrifuges, hydrocyclones or with a static tank. Drying of the minerals 134
can be achieved with,
for example, a drying kiln or other mineral drier such as a "ring" dryer (not
shown in FIG. 2). (In
an alternate embodiment, separation can be facilitated by adding a chemical to
break the
emulsion.)
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[0085] Produced water with solubles 138, resulting from the separation of the
organic liquor
from the water, can be concentrated in an evaporator 250 of a type that is
typically available in the
industry. The organic liquor 500 that has been separated from the minerals and
the water may be
contained in an organic liquor holding vessel 252 prior to transfer to the
third stage reactor 260.
Such a holding vessel may be an ordinary storage vessel as is typically used
in the industry.
[0086] Some portion of the organic liquor 500 may be diverted to give one or
more specialty
chemicals. Typically this involves subjecting the organic liquor to fractional
distillation. The
organic liquor that is subjected to fractional distillation is typically
distilled in a distillation
column 254. The organic liquor may be subjected to an acid wash to separate
out trace amino
acids before passing it to the distillation column. More volatile materials
from the organic liquor,
such as fatty acids, are distilled off and collected. Any heavier materials
such as non-volatilized
fats and fat derivatives that are found in the bottom of the distillation
column are passed on to the
third stage reactor 260.
[0087] The organic liquor that comes from the second stage separation is also
passed to the
third stage reactor 260 wherein a second reaction takes place in which the
organic liquor is
converted into one or more useful materials such as oil, and carbon solids
142. The oil that comes
out of the third stage reactor may be subjected to further separation in a
separator 270, to produce
oil 144 and fuel-gas 146. The separation may comprise condensing the oil in
various steps, and
diverting it to oil storage 280 in a storage vessel. The carbon solids 142
that come from the third
stage reactor are cooled and may also be stored, or further heated and then
treated to activate them
according to methods that are known to one of ordinary skill in the art. For
example, the carbon
solids may be heated in an additional reactor, and be activated by the
injection of superheated
steam.
[0088] As discussed hereinabove, exemplary raw feed materials include waste
products from
the agricultural and food processing industries. Such waste products can
comprise animal parts
such as wings, bones, feathers, organs, skin, heads, blood and necks, soft
tissue, claws and hair.
Typical animal parts are those found in turkey offal and remnants of carcasses
from
slaughterhouses. Other waste products from the food processing industry that
are suitable for
processing with the methods of the present invention include unused grease
from fast food
establishments such as burger franchises, and materials such as dissolved air
flotation (" ]CAF")
sludge from food processing plants. Agricultural waste products can include
animal dung or
manure from sheep, pigs, and cows, and also other materials such as chicken
litter and crop
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residuals. In an exemplary embodiment illustrated in FIGs. 3-5, raw feed 100
is a food processing
byproduct such as turkey offal.
[0089] As shown in FIG. 3, raw feed 100 is initially subjected to preparation
and slurrying 110
to produce a feed slurry 112, accompanied by steam and gases 121. Slurry 112
may be transferred
to feed storage 320 in a feed storage tank ("FST" or homogenizer) via a heat
exchanger 114. In
the FST, the contents are preheated, typically to a temperature between about
60 C and about 150
C, in order to lower viscosity, biologically inactivate the slurry, and help
mixing. The contents
are mixed in the FST to produce conditioned feed slurry 322, a relatively
homogeneous feed
suitable for passing to the first stage reactor. During feed storage, steam
and gaseous impurities
338 are preferably vented 336. Thus, one advantage of the present invention is
that degassing
occurs in the FST so that unwanted gaseous impurities are removed at an early
stage in the overall
process of the present invention. Feed slurry 112 may remain in feed storage
320 for any
convenient time until it is due to be further processed by the methods of the
present invention.
Preferably, the FST supplies a constant feed stream to a high-pressure slurry
pump that pressurizes
the feed and transports it to the first stage reactor.
[0090] For raw feed materials that contain significant amounts of ammonia
(NH3), such as
turkey offal, it is advantageous to remove the free ammonia, either during
preparation 110, in
which case it is one component of steam and gases 121, or during storage 320,
where it is vented
along with steam and gaseous impurities 338. One source of ammonia is the
breakdown of uric
acid found in residual quantities of urine that are often present in
aggregates of animal body parts.
Methods of removing ammonia are within the knowledge of one of ordinary skill
in the art and
include, but are not limited to, separation of the urine content prior to
slurrying, use of enzymatic
degradation, and application of heat. Additionally, ammonia can be converted
by acidification to
a salt such as ammonium sulfate, or ammonium phosphate. In a preferred
embodiment, the FST
comprises two vessels maintained at different conditions. The first such
vessel performs the role
of storage; the second vessel effects the breakdown of proteins, and releases
ammonia.
[0091] The conditioned feed slurry 322 that emerges from feed storage 320 is
subjected to a
first reaction 330, wherein water content in the conditioned feed slurry 322
effects a hydrolysis of
many of the biopolymers present. Sufficient agitation (provided by mixers
and/or recirculation
devices) is provided so that solids are kept in suspension. The first reaction
typically takes from
about 5 to about 60 minutes. The output from the first reaction is a reacted
feed 122. Typically
steam and gas 339 are also released from the first reaction.
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[0092] In the first reaction 330, some degasification takes place in which
partial removal of
nitrogen and sulfur compounds occurs, and deamination and decarboxylation
reactions can take
place in which significant quantities of protein also dissociate into products
such as ammonia, and
potentially carbon dioxide. In practice, for the process of the present
invention, decarboxylation
reactions are unwanted because the products, other than carbon dioxide, are
amines which tend to
be water soluble, and volatile. Thus, in general, deamination reactions are
preferred to
decarboxylation reactions, and the reacted liquid products obtained from the
first stage typically
include carboxylic acids when the feedstock includes material such as proteins
and fats.
Accordingly, since decarboxylation reactions typically occur at higher
temperatures than
deaminations, the first reaction is preferably run at the lowest temperature
possible at which fat
molecules are split. As an alternative, the pH in the first stage can be
shifted by adding acid,
thereby discouraging decarboxylation reactions.
[0093] Removal of the nitrogen and sulfur compounds at this stage, and the
prior preheating
stage, prevents formation of organic nitrogen compounds, ammonia, and various
sulfur
compounds that might become undesirable components of the resulting bioderived
hydrocarbons
if allowed to become processed through the third stage reactor.
[0094] Typical conditions for carrying out the first reaction in this example
are between 150
C to 330 C, though preferably around 250 C, and around 50 atmospheres
pressure, or about 600
psi, as may be obtained in a first stage reactor. Generally, the pressure in
the first stage reactor is
in the range 20-120 atmospheres. The total preheat and first stage heating
time is up to around
120 minutes. Such conditions may be varied according to the feeds to be used.
In one aspect of
the present invention, as applied to feedstocks that contain PVC, the
operating temperature in the
first stage is high enough, and is followed by washing steps, so that chlorine-
containing products
are removed.
[0095] Generally, the first reaction is carried out at temperatures in the
range from about 150
C to about 330 C so that at least one of the following three transformations
can be carried out.
First, proteins are transformed to the individual amino acid residues of which
they are composed.
This can be achieved by hydrolyzing the peptide amide linkage between each
pair of amino acid
residues in the backbone of the protein at temperatures in the range about 150-
220 C. Second,
fat molecules can be broken down to fatty acid molecules, a process that can
occur in the range of
200-290 C. Fats are hydrolyzed to split apart triglycerides to form free
fatty acids and glycerol.
Third, deamination and decarboxylation of amino acids can occur in the first
stage. The
carboxylic acid groups, if allowed to proceed to the third stage reactor,
still attached to their
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respective amino acid moieties, will all be converted to hydrocarbons at
relatively mild operating
conditions. Additionally, there may be some amino acids that are deaminated, a
process that
typically occurs in the temperature range 210-320 C. Thus, in the first stage
alone, virtually all
the protein present in the slurry will be converted to amino acids at
relatively low first stage
operating temperatures. Furthermore, the degree of amino acid deamination can
be controlled by
a judicious choice of first stage operating temperature.
[0096] As would be understood by one of ordinary skill in the art, the actual
conditions under
which the first stage reactor is run will vary according to the feedstock
employed. For example,
animal offal typically utilizes a first reaction temperature in the range
about 200 C to about 250
C. Municipal sewage sludge typically utilizes a first reaction temperature in
the range about 170
C to about 250 C. A feedstock comprising mixed plastics typically utilizes a
first reaction
temperature in the range about 200 C to about 250 C. Tires typically utilize
a first reaction
temperature in the range about 250 C to about 400 C. A typical operating
condition for tire
processing in the first stage reactor of the process of the present invention,
would be at 275 C and
300 psi, with a solvent to tire ratio of 1:1 or less by weight. Such a
processing pressure for a given
temperature is far lower than those reported in other methods of tire
processing and is therefore
more economic.
[0097] The first stage of tire processing may also involve water for removal
of materials
containing elements such as chlorine. Preferably such materials are almost
completely removed
under normal operating conditions. The tire material, solvent and water can be
mixed together for
the first stage, or the tire may be contacted by the solvent and the water
sequentially.
[0098] The pressure in the first stage reactor is typically chosen to be close
to the saturation
pressure of the water at the operating temperature in question. The saturation
pressure is the
pressure that needs to be applied at a given temperature to keep the water
from boiling, and also
depends on the presence and quantity of other gases in the purified feed
slurry. The total pressure
in the reactor is greater than the vapor pressure of the water in the slurry
mixture, so that the water
does not boil off. The pressure is preferably in the range 45-55 atmospheres,
may be in the range
40-60 atmospheres, and may also be in the range 30-70 atmospheres. Typically,
the pressure is
adjusted by amounts up to, and in the range of, 0-100 psi above saturation so
that unwanted gases
may be vented 336 from feed preparation, feed storage, or the first stage
reactor.
[0099] One advantage of the present invention is that the venting during the
feed preparation
110, feed storage 320, and first reaction permits gaseous impurities such as
ammonia, carbon
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dioxide, and sulfur-containing gases to be removed. Typically, the first
reaction 330 gives rise to
sulfur-containing gases from the breakdown of sulfur-containing moieties in
the various bio-
materials. A principal source of sulfur is protein molecules, many of which
have sulfur-bridges
between cysteine residues. The sulfur-containing gases are typically hydrogen
sulfide (H2S), and
mercaptans (alkyl-sulfur compounds) such as methyl mercaptan. Additionally,
some salts such as
calcium sulfide (CaS) may be produced, and these are normally separated during
later stages.
[0100] After the first reaction, the reacted feed 122 that typically comprises
at least one
reacted liquid product and at least one reacted solid product and water, is
flashed 340 to a lower
pressure, and permitted to release excess heat back to the heating stages
prior to the first reaction.
Typically, flashing is achieved through multiple pressure reductions,
preferably in two to three
stages. The effect of flashing is to vent off remaining steam and gases 132
associated with the
reacted feed. Dehydration via depressurization is efficient because water is
driven off without
using heat. The effective use of the excess heat is known as heat recovery,
and represents a
further advance of the process of the present invention. The fact that the
first reaction uses water,
which may be vented as steam, along with other gases 339, lends itself to
efficient energy
recovery. Water and steam are effective in heat exchange and may be redirected
to the heating
stages before the first reaction using one or more condensers. Condensers are
quite compact and
promote efficiency. Thus, steam and gases 132 vented from the reacted feed 122
are also
preferably used to assist in heating the influent feed and in maintaining the
temperature of the first
reaction, thereby reducing the energy loss of the process of the present
invention. Steam and
gases 339 may also be passed to one or more heat exchangers placed prior to,
or after, feed storage
320. Steam may also be directly injected back into the incoming feed 100 in
some cases.
Preferably, steam and gases 339 from first reaction 330 are combined with
steam and gases 132
prior to passing to heat exchanger 114.
[0101] In the heat exchanger 114, the steam and gases are separated from one
another. Most
of the steam condenses to give a condensate 151. Preferably this condensate is
redirected to
combine with "produced water" that results from later stages of the process of
the present
invention, further described hereinbelow. Residual, small, amounts of steam
are vented 116 along
with the gases. Preferably these vented gases are combined with other gases
that are produced by
later stages of the process of the present invention to give fuel gas.
[0102] After the reacted feed has been flashed 340, and heat has been
recovered, the
intermediate feed 400 typically comprises at least one reacted liquid product,
at least one reacted
solid product, and water. The at least one reacted liquid product is typically
a constituent of an
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organic liquor; the at least one reacted solid product typically comprises
minerals. The
intermediate feed preferably is substantially free of gaseous products.
[0103] FIG. 4 shows a sequence of separations that is applied to the
intermediate feed. It is
another advantage of the process of the present invention that the
intermediate feed that results
from the first reaction is subjected to one or more separation stages that
removes minerals and
water before processing in the third stage reaction. The separation stage uses
separating
equipment such as centrifuges, hydrocyclones, distillation columns, filtration
devices, and screens,
and may also use distillation to remove very fine carbon solids from an
intermediate feed 400. In
general, further pressure reduction recovers more steam, and facilitates
solid/liquid separation to
recover minerals and other solids.
[0104] Intermediate feed 400, typically comprising organic liquor, water, and
minerals is
preferably subject to a first separation 410 that removes most minerals 412
and produces a mixture
of organic liquor and water 414 that is low in ash. Such a separation is
characterized as a
solid/liquid separation and may be achieved with a first centrifuge or via a
solid/liquid separation
device, for example by mechanical, or non-mechanical methods such as gravity
settling. Minerals
412 that are separated out are typically wet and are thus subjected to a
drying stage 420 before
passing to a dry mineral storage 430. The drying stage typically takes place
under normal
atmospheric conditions. The resulting dry minerals may find considerable
commercial application
as a soil amendment or other industrial precursor.
[0105] The organic liquor/water mixture 414 is subject to a second separation
440 to drive off
the water and leave the organic liquor 500. Such a second separation may be
achieved using a
second liquid/liquid centrifuge (or other separation device). Differences in
gravity allow
centrifugal separation of the produced water and organic liquor. The produced
water 138 that is
driven off contains significant amounts of dissolved small organic molecules
such as glycerol and
some water soluble amino acids that derive from the breakdown of proteins. The
produced water
also typically includes chloride impurities. Separating out such impurities
prior to the third stage
reaction represents an additional benefit of the present invention because
later products are
thereby not contaminated.
[0106] The produced water 138 may be subject to concentration 139, such as by
evaporation,
producing a water condensate 151 that may be recycled within the process of
the present
invention, and a concentrate 153 that is dispatched to a concentrate storage
460. Evaporation is
typically achieved by application of a slight vacuum. The concentrate, which
largely comprises a
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slurry of amino acids, glycerol and, potentially ammonium salts such as
ammonium sulfate or
phosphate, will typically have commercial value as, for example, fertilizers
known as "fish
solubles" that are sold in domestic garden stores.
[0107] It is to be understood that the present invention is not limited to a
separating stage
comprising two steps. Nor is the present invention limited by the order in
which any separation
steps are carried out. Thus, it is consistent with the present invention if
the separation of the
intermediate feed 400 into products such as organic liquor, minerals, and
water occurs in a single
step or in more than two steps. Furthermore, minerals may, in some instances,
be left in the
organic feed by design, and their separation thus need not occur prior to
third stage processing.
[0108] When processing tires with an embodiment of the present invention, a
portion of the
organic liquor may be used as a final product that is a devulcanized tire
feedstock for the
manufacture of rubber products.
[0109] FIG. 5 shows a stage of the process of the present invention wherein
organic liquor 500
resulting from a separation stage of FIG. 4 is subject to a third stage 140 to
produce one or more
useful products. The organic liquor 500 ordinarily goes to a holding vessel
before it is processed
further.
[0110] A portion, or all, of organic liquor 500 can optionally be directed for
processing ahead
of the third stage 140 to yield one or more specialty chemicals 143. According
to such an optional
process, some desired portion of organic liquor 500 is typically subjected to
a separation process
such as fractional distillation 510 or reacted with a compound such as alcohol
to form another
compound, as would be understood by one of ordinary skill in the art. Such a
separation process
generates specialty chemicals 143, and leaves behind a fractionated liquor
145, often referred to as
a "heavy liquor", that comprises higher molecular weight organic molecules
such as triglyceride
oils. Fractionated liquor 145 may be redirected to the third stage 140 for
processing in a similar
manner to organic liquor 500.
[0111] Specialty chemicals 143 are typically organic compounds such as fatty
acids, fatty acid
esters, fatty acid amides, or a range of amino acids. Preferably the specialty
chemicals 143 are
fatty acids. More preferably, specialty chemicals 143 are fatty acids in the
range C12_20. Even
more preferably, the specialty chemicals 143 are fatty acids in the range C16-
20. When the
specialty chemicals 143 are fatty acid amides and fatty acid esters, they are
typically formed by
reaction with fatty acids. The specialty chemicals 143 resulting from a
feedstock such as turkey
offal may find application as lubricants and coatings and paints.
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[0112] In the third stage 140, the water content of the organic liquor 500 is
almost zero, so that
the conditions of the third stage are such that the remaining organic
molecules are broken down
largely by application of a high temperature, rather than by hydrolysis by
excess, or added, water
or steam. Typical conditions for carrying out the third stage are around 400
C, as may be
obtained in a third stage reactor. The third stage typically takes from about
5 minutes to about 120
minutes. In practice, the various phases of the liquor spend varying amounts
of time in the third
stage reactor. For example, the vapors pass through relatively quickly, and
the liquids take longer.
The output from the third stage comprises, separately, a mixture of
hydrocarbon vapor and gases
148 such as carbon dioxide, CO, and nitrogen and sulfur containing compounds,
and carbon solids
142. The carbon solids 142 preferably resemble high quality coke. The mixture
of hydrocarbon
vapor and gases 148 typically contains oil vapor. The conditions of the third
stage are preferably
selected to optimize the purity of the carbon solids 142, and the mixture of
hydrocarbon vapor and
gases 148. Rapid quench of hot vapors, such as the mixture of hydrocarbon
vapor and gases 148,
stops reactions and minimizes carbon char formation after the third stage. In
a preferred
embodiment, rapid quenching of vapors may be achieved by directing the vapors
into a drum full
of water or by multiple quenching steps using thermal fluids and cooling
mediums. Where such
multiple quenching steps are employed, it is advantageous to take multiple
cuts (diesel, gasoline,
etc.) from the oil so that the various fractions can be diverted to separate
commercial applications.
Alternatively, in another embodiment, the oil vapor may be quenched in the
presence of the
incoming organic liquor, thereby also facilitating energy recovery.
[0113] Generally, the third stage is carried out at temperatures in the range
of about 310 C to
about 510 C, so that at least one of the following two transformations can be
carried out. First,
fatty acids are broken down to hydrocarbons. This can be achieved by removing
the carboxyl
group from each fatty acid molecule at temperatures in the range approximately
316-400 C.
Second, hydrocarbon molecules themselves are "cracked" to form a distribution
of molecules of
lower molecular weights, a process that can occur in the range approximately
450-510 C.
Typically, however, hydrocarbon cracking occurs at temperatures above 480 C.
Preferably, the
third stage is carried out at a higher temperature than that for the first
stage. It would be
understood that the temperatures described herein applicable to the third
stage could be varied
without departing significantly from the principles of the present invention.
For example, the
third stage can be effectively carried out in the temperature range about 300-
525 C, as well as in
the range 400-600 C. In some embodiments, the temperature of the third stage
reactor is
between about 400 C and about 510 C.
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[0114] Furthermore, in at least one embodiment, the third stage reactor is
slightly pressurized,
to a pressure between about 15 psig and about 70 psig, i.e., from about 15 psi
above atmospheric
pressure, to about 70 psi above atmospheric pressure. Preferably the pressure
in the third stage
reactor is lower than that in the first stage reactor.
[0115] Carbon solids 142 generated from the third stage are typically first
passed to a carbon
solids cooler 630 wherein the carbon is permitted to lose its residual heat.
After cooling, the
carbon solids 142 are passed to carbon storage 540 and may be sold for a
number of useful
applications. For example, the carbon may be sold as a "soil amendment" for
use in domestic
horticulture because many of the bacteria in soil need a source of carbon. In
particular, the carbon
that is produced is of a quality similar to many forms of "activated carbon"
and thus may also find
application as a material for absorbing vapor emissions in automobiles, or for
use in domestic
water filters. Additionally the carbon, because of its level of purity, may
find application as a
solid fuel, like coal, but without the disadvantage of producing noxious
emissions arising from
combustion of the contaminants typically found in coal products. Also many
environmental
toxicants can be neutralized in a soil matrix by the use of a carbon additive
like the carbon solids
that results from the process of the present invention.
[0116] Instead of, or in addition to carbon solids 142, a useful product
generated by the
process of the present invention can be clean coal. Clean coal is generated
when the raw feed is
raw coal. It has been found that coal fines produced by the process of the
present invention are
advantageously freer of sulfur- and chlorine-containing contaminants than raw
coal typically
available. These properties of the coal generated by the process of the
present invention makes
them particularly attractive as sources of clean-burning fuel.
[0117] The mixture of hydrocarbon vapor and gases 148 produced by the third
stage reactor is
typically directed to a cooler/condenser 850 which separates the mixture into
fuel-gas 146 and a
hydrocarbon oil 144. The fuel-gas 146 has calorific value and may itself be
redistributed
internally within the process of the present invention for the purposes of
providing energy for
heating at various stages or can be used to produce electrical or other forms
of energy for external
or internal use. The oil 144 typically comprises hydrocarbons whose carbon
chains have 20 or
fewer carbon atoms. In this respect the mixture resembles the lighter
components of a fuel-oil
such as a #2 grade diesel oil. Such a product is also commercially saleable.
It is to be understood,
however, that the precise composition of the oil 144 depends upon the
feedstock. Thus the
composition of the oil obtained when the feedstock is composed of tires is
different from the
composition when the feedstock is turkey offal. It has been found that the oil
resulting from
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feedstocks that have a high fat content is rich in olefins, and di-olefins. If
not desired, such olefins
may be removed from the oil by resaturation or separation methods.
[0118] When the raw feedstock is tires, it has been found that the final stage
oil obtained from
hydrocarbon oil 144 - in this case tire-derived hydrocarbons - is a superior
solvent for tires as
compared to other solvents presently utilized in the art. Following a general
principle of
chemistry that "like dissolves like", since the final stage oil comes
ultimately from the tires, its
chemical nature is similar to the original tires and so it is a good solvent
for them. When the raw
feed used with the process of the present invention comprises tires, at least
some of the tire-
derived hydrocarbons are redirected to the input raw feed to assist with
dissolving it prior to or
during the preparation of a slurry. Typically the tire-derived hydrocarbons
have a boiling range of
about 100 C to about 350 C. In a preferred embodiment, the tire-derived
hydrocarbons are
heated prior to application to the tires. In another embodiment, the tire-
derived hydrocarbons are
applied to the tires and the mixture is heated to a temperature between about
200 C and 350 C.
The use of the final stage oil product eliminates the recurring costs of other
solvents, and make-up
quantities thereof.
[0119] In various embodiments of the present invention, the entire spectrum of
constituents of
the final stage oil or only a portion of these constituents can be used to
dissolve tires. Preferably
all of the tire-derived hydrocarbons are redirected to the input raw feed. In
another embodiment,
only the final stage heavy oil product is redirected in this manner. If a
portion of constituents is
used, the separation of the solvent into parts can take place during either
final stage processing or
the 1st stage processing. The use of the final oil product as a solvent makes
the process of the
present invention far more economic than other approaches. Because this oil
will ordinarily not
be available for the first batch of tires to be processed on any given
occasion, another solvent may
additionally be employed to assist with initial breakdown of the tires. Such a
solvent is toluene;
others are known to one of ordinary skill in the art.
[0120] When the raw feed is municipal sewage sludge, it is preferable to
facilitate the
separation of the organic from the inorganic materials. Accordingly, in a
preferred embodiment,
some of the hydrocarbon oil 144, in this case bio-derived hydrocarbons, are
redirected to the raw
feed or the product of the first reaction, in order to assist with floating
the material. In other
embodiments, materials such as trap grease, as are obtained from fast food
outlets for example,
can be used. The principle behind floating the material is that a material
that is lighter than water
is introduced to the raw feed, or the product of the first reaction, to assist
with floating the heavier
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than water organic materials, thereby facilitating the separation of organic
from inorganic
materials. The result is a sludge that is easier to centrifuge than would
otherwise be the case.
[0121] A further advantage of the process of the present invention is that all
of the products
are DNA and pathogen-free. That is, they are free of pathological materials
that are derived from
animal cells, bacteria, viruses, or prions. Such materials do not survive the
process of the present
invention intact. This is an important outcome because there is no risk of
using any of the
products of the process of the present invention in agricultural applications
where there would be a
danger that such molecules could re-enter the food-chain.
[0122] An apparatus for converting reacted liquid product from the separation
stage, such as
an organic liquor, into a mixture of hydrocarbons, and carbon solids, is a
suitable third stage
reactor for use with the process of the present invention. As shown in FIG. 6,
a third stage reactor
600 according to an embodiment of the present invention comprises a heater 610
for heating the
organic liquor, thereby producing a mixture of liquid and vaporized oil; a
reactor 620 for
converting the mixture of liquid and vaporized oil into carbon solids 142, and
a mixture of
hydrocarbon vapor and gases 148; a first cooler 630 for accepting the carbon
solids 142; and a
second cooler 640 for accepting the hydrocarbon vapor and gases. Third stage
reactor 600 may
additionally comprise a fluid-solid separator 624 communicating with reactor
620 for separating
hydrocarbon vapor and gases 148 from carbon solids 142.
[0123] The heater 610 is preferably efficient and compact, comprising a large
number of
internal tubes that give rise to a large surface area for heat exchange. The
heater 610 is typically a
"fired heater". Heater 610 typically has an inlet for accepting organic liquor
and steam 602, and
an outlet for directing heated organic liquor/steam mixture to reactor 620.
Steam 602 in an
amount approximately 2-5% by weight accompanies the organic liquor as it
enters heater 610.
Such a quantity of steam helps uniform heating and prevents residue build-up
on the inside of the
heater. In a preferred embodiment, one or more pre-heaters are used to heat
organic liquor 500
prior to mixing it with steam and/or transferring it to heater 610. Pressure
for the third stage is
imparted by a pump system after storage 500.
[0124] Reactor 620 preferably comprises at least one heated auger, and has and
inlet and an
outlet configured, respectively, to accept a heated mixture of liquid and
vaporized oil from heater
610, and to direct carbon solids and a mixture of hydrocarbons and gases into
a fluid-solid
separator. The heated mixture of liquid and vaporized oil with steam is passed
into the reactor
620 where it splits into carbon solids, and a mixture of hydrocarbon gases
that preferably contains
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constituents of oil and fuel gas. Typically, the carbon solids produced amount
to about 10% by
weight of the mixture of liquid and vaporized oil. In other embodiments,
depending upon the
constituents of the raw feedstock, the carbon solids produced are between
about 5% and about
20% by weight of the mixture of liquid and vaporized oil. In some embodiments
of the present
invention, to avoid build up of excess carbon solids in reactor 620, the
amount of feedstock
processed is adjusted.
[0125] An auger is suitable for producing carbon solids and a mixture of
hydrocarbons
because it permits control of residence time and temperature of the incoming
organic liquor, and
because it permits efficient separation of the carbon solids and the volatile
products. Preferably
the dimensions of the auger are selected so that the purity of the resulting
hydrocarbon mixture
and the carbon solids is optimized. For example, the cross-sectional diameter
of the auger
principally determines the rate of flow of vapors through it. Preferably the
rate of flow is not so
high that dust is carried through with the vapors to produce an impure
hydrocarbon mixture. The
residence time of the heated mixture of organic liquor, vapors and steam, as
it reacts, also
determines the size of the auger.
[0126] Preferably the third stage reactor 600 includes a fluid-solid separator
that
communicates with the outlet of the reactor 620. The fluid-solid separator
preferably has a first
outlet for hydrocarbons and gases, and a second outlet for carbon solids. Some
of the fuel gas
from the mixture of hydrocarbons and gases is preferably redirected back to
heater 610 and burned
to help maintain the temperature in the heater, thereby promoting overall
efficiency of the process
of the present invention.
[0127] The carbon solids - often at a temperature as high as about 500 C -
are directed into a
first cooler, carbon solids cooler 630, which is preferably a cooling auger
which communicates
with the reactor through an air lock device, or optionally the fluid-solid
separator. In some
embodiments of the present invention, more than one cooling auger 630 may be
employed. It is
preferable to introduce water 632 into carbon solids cooler 630 to assist with
the cooling process.
The carbon solids are transferred to a finished product storage system 650,
optionally via a
transfer auger or some other conveyancing device such as a bucket elevator 654
or to another
heater/reactor to activate the carbon solids.
[0123] The second cooler 640 for accepting the mixture of hydrocarbon vapor
and gases
preferably comprises a carbon particulate separator for separating out any
residual carbon solids
and returning them to reactor 620.
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[0129] A modified version of the process of the present invention could be
used to inject
steam into underground tar-sands deposits and then refine the deposits into
light oils at the
surface, making this abundant, difficult-to-access resource far more
available. Experiments also
indicate that the process of the present invention can extract sulfur,
mercury, naptha and olefins -
all saleable commodities - from coal, thereby making the coal burn hotter and
cleaner. Pre-
treating via the process of the present invention also makes some coals more
friable, so less
energy is needed to crush them prior to combustion in electricity-generating
plants.
[0130] For some feedstocks, the process of the present invention employs a
device for
separating fine suspended solids from a fluid as part of the feed preparation
stage. In addition,
many other industrial and commercial applications require suspended solids to
be separated from a
liquid. FIG. 7 illustrates a separating device 700 according to a preferred
embodiment of the
invention that is useful for such separations. Another example of an
application requiring the
separation of a solid suspension is the separation of red and white blood
cells from whole blood.
When the size of the suspended solid particles is large, or their density is
significantly different
from that of the fluid, there are many different types of apparatus that can
separate them. For
example, filters of many different configurations with openings smaller than
the suspended solid
particles can be used for solid material that does not deform significantly
under strain. Clarifiers,
settling chambers, and simple cyclones can be used effectively when there is a
significant density
difference between the solid particles and the fluid. As the size or density
difference become
smaller, active devices using centrifugal forces can be effective. However,
the efficiency of all
these separating devices decreases dramatically for very small particle sizes
with deformable
material that has a density only slightly different from that of the
suspending fluid.
[0131] With respect to a preferred process of the present invention, one
application where the
suspended solids are small, deformable, and have small density difference is
municipal sewage
sludge (MSS). The suspended material in MSS consists primarily of cellular
material and cellular
debris from bacteria and typically has dimensions of about 1 micrometer. This
material is
deformable and has an effective density within 10% of that of the suspending
water medium.
Separating this solid material from water is a preferred step in preparing MSS
as a feedstock for
the process of the present invention. Such separation may be achieved through
use of centrifuges;
however, in a preferred embodiment, separating device 700 is employed.
[0132] According to a preferred embodiment of the present invention, it is
preferable to
employ separating device 700, as illustrated in FIG. 7, for separating solid
and liquid components
of a raw feed such as MSS, prior to further processing by the methods of the
present invention.
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Such a device may also be applied to other industrial or commercial wastewater
sludges whose
solid particulates are deformable, or whose effective density is within about
10% of that of the
liquid phase.
[0133] Device 700 preferably comprises a housing 702 that contains a spinning
assembly 704
mounted in an inner chamber 706 having a frusto-conical shape. The shape of
inner chamber 706
typically comprises a frusto-conical section that has an angle of taper, with
additional sections at
the base and/or at the top of the frustum that house other parts of spinning
assembly 704. The
housing 702 preferably comprises a spinner case bottom 714 and a spinner case
top 716 that are
joined to one another, and that enclose the spinning assembly 704. Separating
device 700 further
comprises an inlet 710 and a first outlet 730 that communicate with the inner
chamber, and a
second outlet 750. Inlet 710 permits introduction of the fluid that contains
the suspended solids
into an annular space 712 between a stationary inner wall 720 of the inner
chamber, and the
spinning assembly.
[0134] The spinning assembly comprises a frusto-conically shaped cylinder with
a hollow
interior, which is preferably made from a spinner bottom 722, connected to a
tapered cylindrical
wall 724 which itself is connected to a spinner top 718. The spinning assembly
is concentrically
mounted on a longitudinal axis 736 of a hollow spindle 726 which rotates at
speeds typically in
the range about 1,000 r.p.m. to about 50,000 r.p.m. In a preferred embodiment
for separation of
MSS, the rotation speed is about 10,000 r.p.m. Preferably the rotation speed
is chosen so as to
minimize chaotic flow. The spinning assembly is tapered so that the effective
cross-sectional area
decreases as the width narrows. Typically the angle of taper is between about
1 and about 10 . In
a preferred embodiment, the angle of taper is between about 2 and about 2.5 ,
and is even more
preferably about 2.25 . The hollow interior of the spinning assembly
communicates with a second
outlet 750.
[0135] Preferably there is a pressure differential between the inlet 710 and
the interior of the
separator device 700. Typically, this pressure differential is between about 3-
150 p.s.i. and is
controlled by two pumps (not shown in FIG. 7).
[0136] The flow rate for different sized separators will scale with the
surface area of the
rotating cylinder. Preferably, the inlet and the annular gap are configured to
provide a flow rate
between about 1 and about 200 gallons per minute. More preferably, the flow
rate is between
about 1 and about 20 gallons per minute. Even more preferably for handling
MSS, the flow rate is
about 10 gallons per minute.
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[0137] The wall 724 of the spinning assembly is perforated. The pore size in
the wall 724 is
typically between about 1 and about 200 micrometers. Preferably, the pore size
is about 50
micrometers. The wall 724 is preferably made of a plastic material such as
HDPE or any other
material that is not hygroscopic, to avoid closure of the pores during
operation.
[0133] The fluid and suspended material flow along the annular passage 712 in
a generally
axial direction while a portion of the fluid flows through the perforated
rotating wall 724 into the
hollow interior 728 of the cylinder. Hollow interior 728 communicates with
hollow spindle 726
through spindle inlet 732. Most of the suspended particles are prevented from
flowing with the
fluid through the perforated cylinder due to shear and centrifugal forces at
the surface of the
rotating cylinder. The rotational speed of the cylinder effectively sets the
shear and centrifugal
forces on the suspended particles, and so can be used to control the minimum
size of the particle
that can be prevented from following the fluid through the perforated
cylinder. The water and
particles that flow into the interior of the cylinder 728 subsequently flow
through spindle inlet 732
into the center of hollow spindle 726, and flow towards spindle outlet 734
before being discharged
through a second outlet 750.
[0139] The material in the annular passage 712 follows a tight spiral flow
path in response to
the motion of the rotating cylinder. Preferably the thickness of annular
passage 712 is constant
along its length. For some applications this annular space may vary from top
to bottom.
Variations in annular space can impart flow conditions near the perforated
spinner surface. A first
outlet 730 for discharging the now concentrated fluid stream is provided at
the. end of the annular
passage away from the entrance.
[0140] The operation of the device of FIG. 7 is preferably orientation-
independent. In a
preferred embodiment, the axis of the tapered cylinder is oriented vertically
with the first outlet
730 at the bottom.
[0141] An advantage of the device of FIG. 7 over other separation devices
known in the art is
that it can process sludges with a wide range of particle characteristics, in
particular including
those with deformable suspended solids in the size range below 1 micrometer or
those that have
densities within 10% of the suspending fluid. In a preferred embodiment, the
annular gap and the
pore size in wall 724 are configured for separating a suspension of municipal
sewage sludge. In
some embodiments of the process of the present invention, many such separators
are used, in
parallel, to achieve high throughput separation of a raw feedstock.
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[0142] It is to be understood that the separator 700 depicted in FIG. 7 is not
drawn precisely to
scale, though the various elements are in approximate proportion to one
another. Thus, separator
700 may be constructed according to ordinary principles familiar to one of
ordinary skill in the art
of mechanical engineering and design.
[0143] In a preferred embodiment, the outer diameter of spinner bottom 722 is
about 2", and
the outer diameter of the spinner top 718 is about 2.2". The preferred length
of spinner case
bottom 714 is between about 7" and about 8". The preferred length of spinner
wall 724 is
between about 4" and about 6", and its preferred thickness is preferably
constant along its length
and is about 1.5". The preferred diameter of outlet 730 in conjunction with
such a spinner is about
0.8" and the outer diameter of the spinner case bottom is preferably about 3".
The outer diameter
of spinner case top is then preferably about 4". Spindle 726 is hollow and
preferably has an inside
diameter of about 0.25". The outside diameter of spindle 726 may vary along
its length and may
be between about 0.5" and about 0.75". The distance between spindle inlet 732
and spindle outlet
734 may be about 6" in such an embodiment. The thickness of annular passage
712 is preferably
about 0.05 to about 0.50 inches.
[0144] The preferred dimensions presented herein are to be taken as but one
illustration, and,
according to design choice and desired throughput, a mechanical engineer of
ordinary skill in the
art would be able to scale up or down the size of the various elements of
separator 700 in order to
achieve operating efficiency.
[0145] The overall apparatus for carrying out the process of the present
invention is preferably
accompanied by a computerized control system that comprises simple controllers
for valves,
pumps, and temperatures. Development of such a system is within the capability
of one of
ordinary skill in the art of computer process control engineering.
[0146] The apparatus of the present invention may be scaled according to need.
For example,
plants that handle many thousands of tons of waste per day can be envisioned,
whereas portable
plants that could be transported on the back of a flatbed truck and that might
only handle one ton
of waste per day can also be built.
EXAMPLES
Example 1: Pilot Plant
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[0147] A pilot plant has been built employing apparatus and processes of the
present
invention. The pilot plant can handle approximately seven tons of waste per
day.
[0148] According to one exemplary application of the pilot plant, the
experimental feedstock
was turkey processing-plant waste: feathers, bones, skin, blood, fat, viscera.
An amount of 10,044
pounds of this material was put into the apparatus's first stage: a 350-
horsepower grinder, which
turns the material into gray-brown slurry. From there, the material flowed
into a series of tanks
and pipes which heated and reformed the mixture.
[0149] Two hours later, a light-brown stream of steaming fine oil was
produced. The oil
produced by this process is very light. The longest carbon chains are C20. The
produced oil is
similar to a mix of half fuel oil, half gasoline.
[0150] The process of the present invention has proved to be 85% energy
efficient for
complex feedstocks such as turkey offal. This means that for every 100 B.t.u.
(British thermal
units) in the feedstock entering the plant, only 15 B.t.u. are used to run the
process. The efficiency
is even better for relatively dry materials, such as carbon-heavy or moisture-
light raw materials
such as plastics.
[0151] The first stage reactor, comprises a tank approximately 20 feet tall,
three feet wide, and
heavily insulated and wrapped with electric-heating coils. In the first stage
reactor, feedstock is
hydrolyzed by means of heat and pressure. Both temperatures and pressures are
not very extreme
or energy-intensive to produce because water assists in conveying heat into
the feedstock. It
usually takes only about 15 minutes for this process to occur in the pilot
plant.
[0152] After the organic materials are heated and partially depolymerized in
the reactor vessel,
a second stage begins. In this phase, the slurry is dropped to a lower
pressure. The rapid
depressurization instantly releases about half of the slurry's free water.
Dehydration via
depressurization is far more efficient than heating and boiling off the water,
particularly because
no heat is wasted. Water that is "flashed-off 'is sent up a pipe that leads
back to the beginning of
the process to heat the incoming process stream.
[0153] In this second stage, the minerals settle out, and get shunted to
storage tanks. In turkey
waste, these minerals come mostly from bones. The minerals come out as a dried
brown-colored
powder that is rich in calcium and phosphorous. It can be used as a fertilizer
because it is well-
balanced in micro-nutrients. In particular it has a useful range of micro- and
macro- nutrients.
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The minerals contain the correct amounts of elements such as calcium and
phosphorous required
for healthy plant growth and development.
[0154] In the pilot plant, the remaining concentrated organic materials flow
into a third stage
reactor and is subjected to third stage processing, as described hereinabove.
Gases resulting from
the processing were used on-site in the plant to heat the process of the
present invention. The oil
and carbon flow into storage as useful higher value products.
[0155] Depending on the feedstock and the first and third stage processing
times, the process
of the present invention can make other specialty chemicals, which are
extracted at various
sections of the process. Turkey offal, for example, can make fatty acids for
use in soap, tires,
paints and lubricants.
Example 2: Operating plant
[0156] A full-sized commercial-scale installation is under construction,
intended to process
over 200 tons of turkey-waste daily. The plant is designed to produce about 10
tons of gas per
day, which returns to the system to generate heat to power the system. The
plant will produce
about 21,000 gallons of water, which is clean enough to discharge into a
municipal sewage
system, and is also free of pathological vectors. The plant also will make
about 25 tons of
minerals, concentrate and carbon, and about 500 barrels of high-quality oil of
the same grade as a
#2 heating oil.
Example 3: Exemplary Conversions of Waste Products
[0157] Table 1 shows end-products, and their proportions, for 100 lbs of each
of the following
waste product, when they are converted to useful materials using the process
of the present
invention: Municipal Sewage Waste (comprising 75% sewage sludge and 25% grease-
trap
waste); Tires; Poultry Processing Waste (comprising organs, bones, blood,
feathers and fat);
Plastic bottles (comprising a blend of Polyethylene Terephthalate (PET) used
to make soda
bottles, and High Density Polyethylene (HDPE) used to make milk jugs); Paper;
Medical Waste
(originates primarily from hospitals and comprises plastic syringes,
transfusion bags, gauze, paper
wrappers and wet wastes); and Heavy Oil (such as refinery-vacuum residues and
tar sands).
Amounts in Table 1 are in pounds.
Table 1
Feedstock Oil Gas Solids & Concentrate Water
Municipal Sewage Sludge 26 9 8 (carbon and mineral solids) t 57
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Tires 44 10 42 (carbon and metal solids) 4
Poultry Processing Waste 39 6 5 (carbon and mineral solids) 50
Plastic bottles 70 16 6 (carbon solids) 8
Paper $ 8 48 24 (carbon solids) 20
Medical Waste 65 10 5 (carbon and metal solids) 20
Heavy Oil 74 17 9 (carbon solids). -
1 For paper, the figures are based on pure cellulose; it is estimated that
yields for specific paper
feedstocks such as newspapers or office waste paper would be within 10% of
these figures.
t The solid output from municipal sewage sludge may also contain heavy metals.
[0158] It is worth noting that the yields from cattle and pork processing
wastes are similar to
those from poultry processing waste.
Example 4: Removal of contaminants from coal fines and high sulfur coal.
[0159] Low detection mercury analysis was carried out on raw fines, high
sulfur coal, and on
the products of the process of the present invention applied to each. In each
case the detection
limit was 0.01 ppm. From coal fines raw feed, the mercury level was 0.12 ppm;
mercury was not
detectable in the processed carbon.
[0160] From high sulfur coal raw feed, the mercury level was 0.02 ppm; mercury
was not
detectable in the processed carbon.
Example 5: Removal of sulfur contaminants from coal fines
[0161] Unprocessed fines contained 1.71 % sulfur. Composite carbon contained
1.58 %
sulfur, a 7.6% reduction from the unprocessed fines. Carbon produced by one
application of the
process of the present invention contained 1.51% sulfur, a 11.6 % reduction
from the raw feed.
Example 6: Removal of sulfur contaminants from high sulfur coal
[0162] Raw feed high sulfur coal contained 2.34% sulfur by weight. After one
application of
the process of the present invention, the resulting solid product contained
2.11% sulfur by weight.
Example 7: Removal of contaminants from low sulfur coal
[0163] Unprocessed coal contained 1.08 % sulfur; carbon obtained from the
process of the
present invention contained 0.49 % sulfur, a reduction of 54.6 %. A very low
concentration of
sulfur (45 ppm) was also detected in produced water.
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[0164] In another application of the process of the present invention to the
same sample,
carbon contained 0.57 % sulfur, a reduction of 47.2 %. The produced gas (the
gas discharged
from the process) from this application contained 0.9 % sulfur by weight, thus
illustrating that the
sulfur driven off ends up largely in gaseous products.
[0165] It is significant that as much as about half of the sulfur-containing
contaminants can be
removed when the initial sulfur-content is already very low.
[0166] The process of the present invention is also effective at removing
mercury. Mercury
was essentially absent from carbon produced by the process of the present
invention, where
detection levels to about 10 ppb were possible. Mercury was detected in the
produced water at
levels of 30 ppb (0.028 ppm) demonstrating that when mercury is removed from
coal, it is
transferred to water. When the mercury is in the water, it is amenable to safe
disposal. The water
is stripped of hydrocarbons, and concentrated down by use of a vacuum
distillation unit. The
resulting mercury-concentrated water is subject to silicate crystallization
and the resulting highly
insoluble silicate crystals would be containerized and stored in a hazardous
waste site rated for
storage of toxic metals.
Example 8: A bio-derived oil
[0167] A bio-derived oil can be produced from a wide range of organic
materials using the
process of the present invention. One such bio-derived oil comes from turkey
offal, comprises C-
20 and shorter carbon-chain components, and virtually eliminates particulate
emissions when used
as a fuel. This oil provides refineries or blenders with a narrow range 40-
plus American
Petroleum Institute (API) renewable oil that can be used as an alternative
fuel, or a blending
component for combustible fuels. Salient properties of this oil are shown in
Table 2, wherein the
specification methods are designated by an ASTM (American Society for Testing
Materials) code.
Table 2
Fuel Property Specification Method Bio-derived Oil
API Gravity at 60 F D-287 40+
Flash Point ( F) D-93 100
Distillation, Recovery, F (Typical) D-86
Initial Boiling Point, F 125
10% 160
20% 220
30% 280
40% 335
50% 400
60% 450
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Fuel Property Specification Method Bio-derived Oil
70% 500
80% 580
90% 660
Recover, Vol. % 95%
Appearance D-4176 Clear and Bright
Cloud Point C D-2500 -10
Pour Point C D-97 -20
Viscosity @ 40 C, cSt D-445 -1.50
Sulfur, Wt.% D-4294 < 0.15
Copper Corrosion Rating (2 hrs @ 212 F) D-130 < 2
Cetane Index D-976 - 40
BS&W (Basic Sediment and water), Vol. % D-2709 < 0.10
Ash, Wt.% D-482 < 0.005
Carbon Residue, Wt.% D-524 < 0.50
Heat Content, BTU/lb D-240 -18,800
PONA, Wt. % (Typical) D-5443
Paraffins 22
Olefins 14
Naphthenes 3
Aromatics 6
C-14/C-14+ 55
[0168] In Table 2, the weight percent of paraffins, olefins, naphthenes, and
aromatics refer to
molecules that contain up to and including 13 carbon atoms.
Example 9: Embodiment of a third stage reactor and cooler/condenser
[0169] FIGs. 8A and 8B show an embodiment of an apparatus for use with the
process of the
present invention. Some elements are also shown in FIG. 6.
[0170] FIG. 8A shows an apparatus for use with the third stage of the process
of the present
invention. Organic liquor 500 passes into a storage tank 812. Optionally,
organic liquor and oil
may be directed to a liquid/liquid separator 814 and divided into a first
portion of fractionated
liquor/oil 816 and a second portion of, or residual, fractionated liquor/oil
822. The first portion of
fractionated liquor/oil may be directed to finished product storage 818, and
distributed as
fractionated liquor/oil 820 which can be recycled or sold. The second portion
of fractionated
liquor/oil 822 is redirected to one or more preheaters 830.
[0171] Having been heated, the fractionated liquor/oil 822, or the unseparated
liquor/oil 500 is
passed to a heater 610, preferably accompanied by steam 602. Resulting liquid
and vaporized
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liquor/oil 836 is passed to a reactor 620, such as an auger, and separated
into hydrocarbon vapor
and gases 148, and carbon solids 142. The hydrocarbon vapor and gases 148 are
passed to a
cooler/condenser 850, which is further described in FIG. 8B. Any remaining
particulates in the oil
vapor and gases, such as residual carbon solids 844, are removed and returned
to the reactor 620.
[0172] Carbon solids 142 are directed through an air lock 846, and into a
carbon solids cooler
630, wherein they are mixed with water 632. The resulting mixture of water and
carbon solids is
passed through another air lock 854 into a finished product storage system
650. Final product
carbon solids 142 may be distributed to one or more commercial applications.
[0173] For use in conjunction with apparatus 800 shown in FIG. 8A, is a
cooler/condenser
850, shown in FIG. 8B. Cooler/condenser 850 facilitates a number of separation
cycles wherein a
mixture of oil vapor and gases, which may also contain water and particulates,
is subject to a
number of different separation steps. Hydrocarbon vapor and gases 148 from
reactor 620 pass
into a carbon particulate separator 842, which separates out remaining solid
particles, such as
residual carbon solids 844, and redirects such solids back to reactor 620.
[0174] The hydrocarbon vapor and gases that emerge from the carbon particulate
separator
pass into a vapor quenching system 860, implemented according to general
principles that would
be understood by one of ordinary skill in the art. From the vapor quenching
system, oil and gases
870 pass into an oil/water/gas separator 872 which further separates the
various components such
as oil 862, slop oil 876, gas and LPG 874, and an oil/carbon slurry 881.
[0175] Oil 862 passes to a heat exchanger 864 and thereafter into a finished
product storage
system 866, and is sold as oil 144.
[0176] Gas and liquid petroleum gas ("LPG") 874 pass into a condenser 890
which separates
out LPG 898 from the other gaseous components. Gas 894 is passed to super
heater 892 to yield a
fuel gas 146, which can be delivered to one or more devices as a source of
energy. LPG 898 is
recycled in the following way. First, LPG 898 is passed through a liquid/solid
separator 884, and
any residual carbon solids 886 are removed. Then, the separated LPG, mixed
with oil separated
from the oil/carbon slurry 881, is returned to the oil/water/gas separator
872, and a further
separation takes place. The cycle wherein the gas and LPG mixture is separated
and condensed
may be repeated as many times as is desired.
[0177] An oil/solid mixture, typically an oil/carbon slurry 881, may also be
directed from
oil/water/gas separator 872 to liquid/solid separator 884 in order to remove
residual carbon solids
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886. The separated oil, mixed with LPG, is preferably returned to the
oil/water/gas separator for
further redirection, as appropriate.
[0178] Slop oil 876 from oil/water/gas separator 872 is passed to an oil/water
separator 878,
and water 880 is released, or may be recycled. Oil 882 from the oil/water
separator is passed back
to the oil/water/gas separator for further iterations of the separation cycle.
[0179] The foregoing description is intended to illustrate various aspects of
the present
invention. It is not intended that the examples presented herein limit the
scope of the present
invention. The invention now being fully described, it will be apparent to one
of ordinary skill in
the art that many changes and modifications can be made thereto without
departing from the spirit
or scope of the appended claims.
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