U.S. patent application number 12/646695 was filed with the patent office on 2010-06-24 for system for production of ethanol and co-products with separation and solvent washing of fermentation product.
This patent application is currently assigned to POET Research, Inc.. Invention is credited to Steven G. Redford.
Application Number | 20100159549 12/646695 |
Document ID | / |
Family ID | 42266497 |
Filed Date | 2010-06-24 |
United States Patent
Application |
20100159549 |
Kind Code |
A1 |
Redford; Steven G. |
June 24, 2010 |
SYSTEM FOR PRODUCTION OF ETHANOL AND CO-PRODUCTS WITH SEPARATION
AND SOLVENT WASHING OF FERMENTATION PRODUCT
Abstract
A system for the production of ethanol and co-products is
provided. The system facilitates an overall reduction in the use of
energy, for example, by reducing the mass of wet solids supplied to
a distillation system. The system also reduces the amount of energy
used to dry the wet solids component of a fermentation product, for
example, by increasing the ethanol concentration of the wet solids.
The system also facilitates the recovery of co-products including
bioproducts and other biochemicals extracted from components of the
fermentation product. The solids component of the fermentation
product may be dried and constituted into a meal that may be used
for animal feed, among other uses.
Inventors: |
Redford; Steven G.;
(Brandon, SD) |
Correspondence
Address: |
FLETCHER YODER P.C.
7915 FM 1960 RD. WEST, SUITE 330
HOUSTON
TX
77070
US
|
Assignee: |
POET Research, Inc.
Sioux Falls
SD
|
Family ID: |
42266497 |
Appl. No.: |
12/646695 |
Filed: |
December 23, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61140454 |
Dec 23, 2008 |
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61161342 |
Mar 18, 2009 |
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61161622 |
Mar 19, 2009 |
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61162097 |
Mar 20, 2009 |
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61161684 |
Mar 19, 2009 |
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61168331 |
Apr 10, 2009 |
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61179347 |
May 18, 2009 |
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61179348 |
May 18, 2009 |
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Current U.S.
Class: |
435/161 |
Current CPC
Class: |
A23K 40/20 20160501;
A23K 40/25 20160501; A23K 10/38 20160501; Y02P 60/87 20151101; A23K
10/37 20160501; Y02E 50/10 20130101 |
Class at
Publication: |
435/161 |
International
Class: |
C12P 7/06 20060101
C12P007/06 |
Claims
1. A method for processing a fermentation product of a fermentation
process in a biorefinery that performs distillation of ethanol, the
fermentation product comprising a liquid component and a solids
component, the method comprising the steps of: (a) separating the
liquid component from the solids component prior to distillation of
the liquid component; (b) applying a solvent to the solids
component to alter the composition of the solids component; and (c)
drying the solids component, wherein the solids component is not
exposed to heat added to the liquid phase product during the
distillation process.
2. The method of claim 1 wherein the solids component comprises
particulate matter, the particulate matter being separated from the
liquid component prior to distillation of the liquid component.
3. The method of claim 1 wherein the solids component is separated
from the liquid component by centrifuging.
4. The method of claim 1 wherein the solids component comprises
proteins derived from corn.
5. The method of claim 1 wherein the solvent comprises hexane.
6. The method of claim 1 wherein the solvent comprises ethanol.
7. The method of claim 6 wherein the solids component comprises a
moisture content comprising an ethanol component and a water
component, and wherein the composition of the solids component is
altered by decreasing the water component.
8. The method of claim 7 wherein the composition of the solids
component is altered by increasing the ethanol component.
9. The method of claim 7 comprising collecting liquid and/or gas
from the solids component, and increasing ethanol content of the
liquid and/or gas collected from the solids component to obtain a
higher ethanol-content liquid, and wherein the higher
ethanol-content liquid is applied to the solids component.
10. The method of claim 9 wherein the liquid and/or gas is
collected from the solids component by application of at least one
of a positive pressure, a vacuum pressure, and heat to the solids
component.
11. The method of claim 7 comprising performing step (b) at least
twice to drive the components of the moisture content towards the
water/ethanol azeotropic point.
12. The method of claim 11 wherein performance of step (b) is
stopped, and the solids component is dried prior to reaching the
water/ethanol azeotropic point.
13. The method of claim 7 comprising performing step (b) up to or
beyond the water/ethanol azeotropic point.
14. The method of claim 13 comprising performing step (b) until the
moisture content is substantially entirely ethanol.
15. The method of claim 7 wherein the ethanol is produced by
distillation of the liquid component of the fermentation
products.
16. The method of claim 1 comprising removing a portion of the
solids component bioproduct from the solids component prior to
drying.
17. The method of claim 1 wherein the solids component comprises
meal.
18. The method of claim 1 wherein in steps (b) and (c) the average
temperature of the solids component is maintained below a
temperature that will result in degradation of the solids
component.
19. The method of claim 18 wherein in steps (b) and (c) the average
temperature of the wet solid fermentation product is maintained
below 150.degree. C.
20. The method of claim 19 wherein in step (b) and (c) the average
temperature of the wet solid fermentation product is maintained
below 100.degree. C.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from and the benefit of and
incorporates by reference, each of the following: (a) U.S.
Provisional Application Ser. No. 61/140,454, entitled FORMING DRIED
SOLID FROM A FERMENTATION PROCESS, filed Dec. 23, 2008; (b) U.S.
Provisional Application Ser. No. 61/161,342, entitled PROCESS FOR
LOW ENERGY DRYING OF ETHANOL FERMENTATION SOLIDS, filed Mar. 18,
2009; (c) U.S. Provisional Application Ser. No. 61/161,622,
entitled PROCESS FOR LOW ENERGY DRYING OF ETHANOL FERMENTATION
SOLIDS, filed Mar. 19, 2009; (d) U.S. Provisional Application Ser.
No. 61/161,684, entitled LOW ENERGY DRYING OF ETHANOL FERMENTATION
SOLIDS WITH REDUCTION OF NON-FERMENTABLE INPUTS, filed Mar. 19,
2009; (e) U.S. Provisional Application Ser. No. 61/162,097,
entitled LOW ENERGY DRYING OF ETHANOL FERMENTATION SOLIDS WITH
MULTIPLE ETHANOL FEEDS, filed Mar. 20, 2009; (f) U.S. Provisional
Application Ser. No. 61/168,331, entitled PROCESS FOR PRODUCING
ETHANOL, filed Apr. 10, 2009; (g) U.S. Provisional Application Ser.
No. 61/179,347, entitled PROCESS FOR PRODUCING ETHANOL, filed May
18, 2009; and (h) U.S. Provisional Application Ser. No. 61/179,348,
entitled PROCESS FOR PRODUCING ETHANOL, filed May 18, 2009.
BACKGROUND
[0002] Ethanol can be produced from grain-based feedstocks (such as
corn), cellulosic feedstocks (such as switchgrass or corn cobs), or
other plant material (such as sugar cane).
[0003] In a conventional ethanol plant producing ethanol from corn,
corn kernels are processed to separate the starch-containing
material (e.g. endosperm) from other matter (such as fiber and
germ). The starch-containing material is then slurried with water
and liquefied to facilitate saccharification where the starch is
converted into sugar (i.e. glucose) and fermentation where the
sugar is converted by an ethanologen (i.e. yeast) into ethanol. The
product of fermentation is beer, which comprises a liquid component
containing ethanol and water (among other things) and a solids
component containing unfermented particulate matter (among other
things).
[0004] According to the process typically used at a conventional
ethanol plant, the liquefaction of the starch-containing material
is done by "cooking" the slurry at temperature at or near boiling
point of water. According to an alternative process (that has been
developed and implemented by the assignee of the present
application), for example, as described in U.S. Patent Application
Publication No. 2005/0239181, raw starch may be converted and
fermented without "cooking" or liquefication.
[0005] In a conventional ethanol plant, the liquid component and
solids component of the fermentation product is sent to a
distillation system. In distillation, the fermentation product is
processed into, among other things, ethanol and stillage containing
wet solids (i.e. the solids component of the beer with
substantially all ethanol removed) formed into a wet cake which can
be dried into distillers dried grains (DDG) and sold as an animal
feed product. Other co-products, for example, syrup (and oil
contained in the syrup) can also be recovered from the stillage.
Water removed from the fermentation product in distillation can be
treated for re-use at the plant.
[0006] In a conventional ethanol plant, certain plant operations
are conducted at elevated temperatures over ambient temperature
with the resultant consumption of energy. For example, the
liquefaction of the starch-containing slurry is typically done with
a jet cooker (using natural gas as a fuel to elevate the
temperature of the slurry to a boil). The amount of energy used in
the distillation process (another operation performed at an
elevated temperature, with heat typically provided by steam from an
on-site boiler) is a function, among other things, the volume/mass
of material supplied to the distillation system. And the drying of
wet solids into distillers dried grains, an operation in which
water is removed from the solids typically in a dryer (such as a
ring dryer) heated by natural gas, will consume energy as a
function of the properties (e.g. heat capacity, heat of
vaporization and boiling point) of the water to be removed from the
solids.
[0007] It would be advantageous provide for a system for producing
ethanol that facilitates an overall reduction in the use of energy
at the plant, for example, by reducing the mass of wet solids
supplied to the distillation system. It would also be advantageous
to provide for a system for producing ethanol that reduced the
amount of energy used to dry the wet solids component of the
fermentation product. It would further be advantageous to provide
for a system for producing ethanol that facilitated the recovery of
co-products including bioproducts and other biochemicals extracted
from components of the fermentation product. It would further be
advantageous to provide for a system for producing ethanol in which
the solids component of the fermentation product would be dried and
constituted into a meal that could be used for animal feed, among
other uses.
SUMMARY
[0008] The present invention relates to a system and method for
processing a fermentation product of a fermentation process in a
biorefinery that performs distillation of ethanol, the fermentation
product comprising a liquid component and a solids component, the
method comprising the steps of: (a) separating the liquid component
from the solids component prior to distillation of the liquid
component, (b) applying a solvent to the solids component to alter
the composition of the solids component, and (c) drying the solids
component, wherein the solids component is not exposed to heat
added to the liquid phase product during the distillation
process.
DRAWINGS
[0009] FIG. 1 is a process flow diagram of an exemplary embodiment
of a biorefinery.
[0010] FIG. 2 is a process flow diagram of an exemplary embodiment
of the biorefinery of FIG. 1.
[0011] FIG. 3 is a process flow diagram of an exemplary embodiment
of the biorefinery of FIG. 1.
[0012] FIG. 4 is a process flow diagram of an exemplary embodiment
of the biorefinery of FIG. 1.
[0013] FIG. 5 is a process flow diagram of an exemplary embodiment
of the biorefinery of FIG. 1.
[0014] FIG. 6 is a block flow diagram of an exemplary embodiment of
the biorefinery.
[0015] FIG. 7 is a block flow diagram of an exemplary embodiment of
the biorefinery.
[0016] FIG. 8 is a block flow diagram of an exemplary embodiment of
the biorefinery.
[0017] FIG. 9 is a block flow diagram of an exemplary embodiment of
the biorefinery.
[0018] FIG. 10 is a block flow diagram of an exemplary embodiment
of the biorefinery.
[0019] FIG. 11 is a block flow diagram of an exemplary embodiment
of the biorefinery.
[0020] FIG. 12 is a block flow diagram of an exemplary embodiment
of the biorefinery.
[0021] FIG. 13 is a block flow diagram of an exemplary embodiment
of solids washing processes.
[0022] FIG. 14 is a process flow diagram of an exemplary embodiment
of the solids washing processes.
[0023] FIG. 15 is an exemplary graphical representation of energy
for drying wet solids vs. the ethanol concentration of the wet
solids.
[0024] FIG. 16 is a block flow diagram of an exemplary embodiment
of the solids washing processes.
[0025] FIG. 17 is a process flow diagram of an exemplary embodiment
of the solids washing processes.
[0026] FIGS. 18A and 18B are cross-sectional views of an exemplary
embodiment of a wash process capable of implementing multiple wash
stages.
[0027] FIGS. 19 through 23 are cross-sectional views at various
locations along the filter belt of FIGS. 18A and 18B.
[0028] FIG. 24 is a perspective view of an exemplary embodiment of
the ethanol wash process.
[0029] FIG. 25 is a flow chart of the exemplary embodiment of the
solids washing processes.
[0030] FIG. 26 is a flow chart of the exemplary embodiment of
multiple solids washing processes.
[0031] FIG. 27 is a process flow diagram of an exemplary embodiment
of the fractionation process.
[0032] FIG. 28 is a block flow diagram of an exemplary embodiment
of the saccharification process.
[0033] FIG. 29 is a block flow diagram of an exemplary embodiment
of the fermentation process.
[0034] FIG. 30 illustrates exemplary embodiments of the separation
process.
DETAILED DESCRIPTION
[0035] FIG. 1 is a process flow diagram of an exemplary embodiment
of a biorefinery 10. Biorefinery 10 receives a feedstock,
illustrated as corn 12, and processes the feedstock to produce
several usable products for consumption, principally ethanol.
Although illustrated as corn 12, other types of feedstock such as
sorghum, wheat, barley, potatoes, sugar cane, switchgrass, and corn
cobs, may be processed by biorefinery 10. Additional inputs such as
enzymes, yeast, water, and energy (e.g., heat energy) may be added
to the feedstock to facilitate production of the usable products.
The usable products from biorefinery 10 may include bioproducts 14,
such as corn oil, corn syrup, bran, flour, proteins (e.g., zein),
and other suitable bioproducts, ethanol 16, and an animal feed 18
shown as distillers dried grain (DDG).
[0036] Ethanol 16 is an alcohol produced from corn 12 or other
starch-based crop. Ethanol 16 has many uses, and of particular
interest is its capacity to be blended with gasoline for use in
motor vehicles 20. Ethanol 16 is a relatively clean-burning,
high-octane fuel that may be produced domestically in the United
States from renewable sources, reducing the dependence on foreign
sources of energy. Ethanol 16 also delivers economic vitality to
agricultural regions where the feedstocks are produced. Ethanol
blends increase fuel octane ratings, decrease harmful fossil fuel
emissions, reduce fuel costs, and extend the overall supply of
gasoline.
[0037] FIG. 2 is a process flow diagram of an exemplary embodiment
of biorefinery 10 of FIG. 1. Corn 12 may be directed into a
preparation/fractionation process 24, where corn kernels of corn 12
may be separated into non-fermentable solids (e.g., germ and fiber)
and fermentable solids (e.g., endosperm). Once the endosperm has
been separated from the non-fermentable solids, the endosperm may
be ground into ground endosperm, which may be directed into a
saccharification process 26. Separation and grinding of endosperm
may also be conducted in an integrated process. Saccharification
process 26 may also receive additional inputs (e.g., heat, water,
and enzymes) and may convert starches within the ground endosperm
into sugars, which may be suitable for fermenting. A fermentation
slurry may be directed from saccharification process 26 into a
fermentation process 28.
[0038] Fermentation process 28 may also receive additional inputs
(e.g., yeast and enzymes) and may ferment the sugars within the
fermentation slurry to produce a certain concentration of ethanol
within the fermentation slurry. Fermentation process 28 may produce
a certain amount of carbon dioxide (CO.sub.2) and other gases,
which may be processed through the use of a scrubber 30 or other
suitable equipment. The main product of fermentation process 28 is
a fermentation product shown as beer 32 comprises a liquid
component and a solids component and is generally a mixture of
ethanol, water, syrup, particulate matter, and dissolved solids.
Saccharification process 26 and fermentation process 28 may be
performed separately, or according to certain embodiments, may be
combined into a substantially integrated process (e.g., called
simultaneous saccharification and fermentation (SSF)).
[0039] Beer 32 may be directed into solids processing system 34,
which may wash beer 32 with ethanol (or other solvent). Solids
processing system 34 of FIG. 2 include a separation/wash process
36, a separation process 38, and a desolventizing process 40. Beer
32 may be separated into a liquid component and a solids component
by separation/wash process 36. The liquid component from
separation/wash process 36 may be processed by a series of
distillation system 42, which primarily produce ethanol 16.
Distillation system 42 may include a distillation pre-treatment
process 44, a distillation process 46, and a dehydration/filtration
process 48. Distillation pre-treatment process 44 may remove wet
solids components from the liquid component before distillation
process 46 produces ethanol, which may be dried within
dehydration/filtration process 48 to remove any remaining water 49.
Dehydration/filtration process 48 may include any suitable type of
dehydration, such as dessication. Water 49 removed from
distillation system 42 may be used as make-up water, as a slurry
water source, or as a source of water for other processes internal
or external to biorefinery 10.
[0040] The solids component comprises ethanol, water, syrup, meal,
zein, lutein, lysine, various proteins (having different attributes
and nutritional values), yeast, fiber, and other particulate matter
and dissolved solids. The solids component may be processed through
solids processing system 34, which primarily produces meal 18 and
several biochemicals, such as zein and xanthophylls. Ethanol 16
from distillation process 46 and/or dehydration/filtration process
48 may be used in separation/wash process 36 to wash the solids
component with ethanol, increasing the ethanol concentration of the
solids component and reducing the energy required to desolventize
the solids component in the desolventizing process 40 to produce
meal 18. Liquids removed by separation process 38 and
desolventizing process 40 may be directed to separation/wash
process 36.
[0041] FIG. 3 is a process flow diagram of an exemplary embodiment
of biorefinery 10 of FIG. 1. The processes are substantially
similar to those of FIG. 2 through the production of beer 32. Beer
32 may be directed into a separation process 50, which separates
the beer 32 into a liquid component and a solids component. The
liquid component from separation process 50 may be processed by
distillation processes operating through distillation system 42 to
produce ethanol 16.
[0042] The solids component may be directed into a wash process 52,
which washes the solids component with ethanol 16 from distillation
process 46 and/or dehydration/filtration process 48. Biochemicals
removed by wash process 52 may be extracted by a biochemical
extraction process. Certain components from wash process 52 may be
directed into distillation system 42 (e.g., distillation
pre-treatment process 44). Ethanol-washed solids from wash process
52 may be directed into separation process 38, where a certain
amount of water and ethanol may be removed before the ethanol
(e.g., solvent) is removed by desolventizing process 40 to produce
meal 18. Liquids removed by separation process 38 and
desolventizing process 40 may be directed to wash process 52.
[0043] FIG. 4 is a process flow diagram of an exemplary embodiment
of biorefinery 10 of FIG. 1. The processes are substantially
similar to those of FIGS. 2 and 3 through the production of beer
32. Beer 32 may be directed into distillation process 46, with
ethanol from distillation process 46 being directed to
dehydration/filtration process 48, and the liquid/solids mixture
(e.g., stillage) from distillation process 46 being directed into
separation/wash process 36. Separation/wash process 36 may receive
ethanol from distillation process 46 and/or dehydration/filtration
process 48 and wash the liquid/solids mixture (e.g., stillage) from
distillation process 46 with the ethanol, increasing the ethanol
concentration of the liquid/solids mixture (e.g., stillage). The
ethanol-washed liquid/solids mixture (e.g., stillage) may be
directed into separation process 38, where a certain amount of
water and ethanol may be removed before the ethanol (e.g., solvent)
is removed by desolventizing process 40 to produce distillers dried
grain (DDG) 54. Liquids removed by separation process 38 and
desolventizing process 40 may be re-cycled back through
separation/wash process 36. Biochemicals and stillage may be
extracted from separation/wash process 36.
[0044] FIG. 5 is a process flow diagram of an exemplary embodiment
of biorefinery 10 of FIG. 1. The processes are substantially
similar to those of FIGS. 2 through 4 through the production of
beer 32. Beer 32 may be directed into wash process 52, which may
wash beer 32 with ethanol from distillation process 46 and/or
dehydration/filtration process 48. The ethanol-washed beer 32 may
be directed into separation process 38, where a certain amount of
water and ethanol may be removed before the ethanol (e.g., solvent)
is removed by desolventizing process 40 to produce meal 18. Liquid
removed by separation process 38 and desolventizing process 40 may
be re-cycled back through wash process 52. Ethanol and water from
wash process 52, separation process 38, and desolventizing process
40 may also be directed into distillation system 42 (e.g.,
distillation pre-treatment process 44).
[0045] FIG. 6 is a block flow diagram of an exemplary embodiment of
biorefinery 10. Corn 12 may first be directed into
preparation/fractionation process 24, where it is prepared for
saccharification and fermentation. Non-fermentable solids in corn
12 may be separated (e.g., fractionated) from fermentable solids.
Corn kernels generally comprise endosperm, germ, and fiber.
Endosperm comprises most of the starches and proteins available in
a corn kernel and, therefore, is used in fermentation process 28 to
generate ethanol. In other words, endosperm represents the
fermentable solids of a corn kernel; germ and fiber represent the
non-fermentable solids, which may be withheld from fermentation
process 28. Endosperm comprises approximately 80-85% of a corn
kernel, germ comprises approximately 10-15% of a corn kernel, and
fiber comprises approximately 5-10% of a corn kernel, all by
mass.
[0046] Non-fermentable solids 56 may be directed into various
bioproduct processes, which may produce usable bioproducts 14.
Non-fermentable solids 56 may include the germ and fiber of corn
12, which may be processed into bioproducts such as corn oil, corn
syrup, bran, flour, and proteins (e.g., zein). Fermentable solids
58 (e.g., endosperm of corn 12) from preparation/fractionation
process 24 may be directed into a saccharification/fermentation
process 60, which may include saccharification process 26 and
fermentation process 28. Saccharification process 26 and
fermentation process 28 may be conducted separately (e.g., in
separate stages) or may be conducted concurrently (e.g., in an
integrated stage). It should be noted that fermentable solids 58
may contain small portions of non-fermentable components (e.g.,
germ and fiber) not intended for the fermentation process.
[0047] Preparation/fractionation process 24 may include passing
corn 12 through mills, such as hammer mills and pins mills, to
grind fermentable solids 58 into a fine powder (e.g., flour),
further facilitating saccharification/fermentation process 60.
Fermentable solids 58 (e.g., endosperm) include a high proportion
of starches suitable for fermenting to produce ethanol 16.
Saccharification/fermentation process 60 may include saccharifying
fermentable solids 58 to convert the starches within fermentable
solids 58 into sugars. The process of saccharifying fermentable
solids 58 may include adding heat, water, and enzymes to
fermentable solids 58 to produce a fermentation slurry.
[0048] Saccharification/fermentation process 60 may also include
adding yeast to the fermentation slurry. The yeast helps convert
the sugars within the fermentation slurry into ethanol 16 and
carbon dioxide. The fermentation slurry may be agitated and cooled
until the concentration of ethanol 16 has been maximized. The
output from saccharification/fermentation process 60 may be
referred to as fermentation product 32, which may generally include
ethanol 16, but may also include a certain amount of water, as well
as syrup, particulate matter, and dissolved solids.
[0049] Fermentation product may be separated by separation process
50 into a liquid component and a solids component, both of which
may be processed in respective processing paths. The liquid
component may include liquid 62, which contains ethanol 16, a
certain amount of water and other non-ethanol liquids, as well as
fine solids, which may be removed from liquid 62. Distillation
system 42 may remove most of the water, other non-ethanol liquids,
and fine solids to produce ethanol 16. Ethanol 16 leaving
distillation system 42 may contain various target concentrations of
ethanol, such as from approximately 95% (e.g., 190 proof) to
approximately 100% (e.g., 200 proof). Stillage 66 (e.g., comprising
liquid and wet solids) from distillation system 42 may be processed
and/or combined into bioproducts 14 (e.g., animal feed, oils,
syrup, and other biochemicals).
[0050] The solids component may include wet solids 64, which may
include a certain amount of ethanol, a certain amount of water,
syrup, particulate matter, and dissolved solids. It should be noted
that when reference is made to "solids," the solids may include
particulate matter and dissolved solids, which may be associated
with a certain amount of liquids (e.g., "wet solids"). Solids
processing system 34 and desolventizing process 40 may remove most
of the water and ethanol from wet solids 64 to produce meal 18.
Solids processing system 34 may include washing wet solids 64 with
ethanol or a liquid with a desired ethanol content to decrease the
boiling point, specific heat, and enthalpy (heat) of vaporization
of the wet solids 64, reducing the energy required to dry (e.g.,
desolventize) wet solids 64 to produce meal 18. The ethanol may be
directed to solids processing system 34.
[0051] FIG. 7 is a block flow diagram of an exemplary embodiment of
biorefinery 10. The processes are substantially similar to those of
FIG. 6 through the production of beer 32. The fermentation product
shown as beer 32 may be directed into distillation system 42, where
beer 32 is distilled to produce ethanol 16. Stillage 66 from
distillation system 42 may be directed into solids processing
system 34 (e.g., including separation and washing), where stillage
66 may be washed with ethanol from distillation system 42 and/or
desolventizing process 40 to increase the ethanol concentration of
stillage 66, reducing the amount of energy required by
desolventizing process 40 to remove liquids from stillage 66 to
produce DDG 54. Thin stillage may be removed from solids processing
system 34 as bioproducts 14.
[0052] FIG. 8 is a block flow diagram of an exemplary embodiment of
biorefinery 10. The processes are substantially similar to those of
FIGS. 6 and 7 through the production of the fermentation product
shown as beer 32. Beer 32 may be separated by separation process 50
into a liquid component shown as comprising liquid 62 and a solids
component shown as comprising wet solids 64. Ethanol 16 may be
recovered from liquid 62 by distillation system 42; wet solids 64
may be directed into solids processing system 34, where solids may
be washed with a solvent 68 (e.g., hexane) other than ethanol.
Solvent 68 may be received by solids processing system 34 from a
solvent conditioning process 70, which may in turn receive spent
solvent from solids processing system 34, forming a closed-loop
cycle of solvent 68 through solids processing system 34. Solvent
from solvent-washed wet solids 64 may be removed by desolventizing
process 40 to produce meal 18. Solvent conditioning process 70 may
also remove a ethanol/water mixture 71 and direct the ethanol/water
mixture 71 to distillation system 42. Solvent conditioning process
70 may further remove water 72 and extracted co-products 74 from
wet solids 64.
[0053] FIG. 9 is a block flow diagram of an exemplary embodiment of
biorefinery 10. The processes are substantially similar to those of
FIGS. 6 through 8 through the production of the fermentation
product shown as beer 32. Beer 32 may be directed into distillation
system 42, where beer 32 is distilled to produce ethanol 16.
Stillage 66 from distillation system 42 may be directed into solids
processing system 34 (e.g., separation and washing), where stillage
66 may be washed with solvent 68 (e.g., hexane). Solvent 68 may be
received by solids processing system 34 from solvent conditioning
process 70, which may in turn receive spent solvent from solids
processing system 34, forming a closed-loop cycle of solvent 68
through solids processing system 34. Solvent from solvent-washed
wet solids 64 may be removed by desolventizing process 40 to
produce DDG 54. Solvent conditioning process 70 may further remove
water 72 and extracted co-products 74 from stillage 66. Thin
stillage may be removed from solids processing system 34 as
bioproducts 14.
[0054] FIG. 10 is a block flow diagram of an exemplary embodiment
of biorefinery 10. Biorefinery 10 begins with
preparation/fractionation process 24, which may include a
preparation process 76 and/or a fractionation process 78.
Preparation/fractionation process 24 prepares corn 12 for
saccharification and fermentation in saccharification process 26
and fermentation process 28.
[0055] Preparation process 76 may include a cleaning stage to
remove impurities that may be present in the corn, such as stalks,
cobs, stone, sand, and other fine particles. Clean corn output from
the cleaning stage may be directed into a water tempering stage,
where corn 12 may be tempered with a water concentration for a
period of time. In the water tempering stage, the water penetrates
the germ and fiber of corn 12, facilitating subsequent removal of
the germ and fiber from corn 12, as well as increasing resistance
of the germ and fiber to physical breakage during subsequent stages
(e.g., further separation).
[0056] Tempered whole corn 12 from preparation process 76 may then
be directed into fractionation process 78. Corn 12 may be
fractionated into non-fermentable solids 56 (e.g., primarily germ
and fiber) and fermentable solids 58 (e.g., primarily endosperm)
with fermentable solids 58 being milled to reduce the particle size
of fermentable solids 58. The downstream processes of biorefinery
10 may not require that corn 12 be fractionated into endosperm,
germ, and fiber. For example, separation process 50 and solids
processing system 34 do not require fractionated corn 12 to lead to
beneficial results, although such fractionation may enhance the
benefits.
[0057] The ground endosperm from fractionation process 78 may be
directed into saccharification process 26, in which starch within
the endosperm may be converted into sugars that can be fermented by
a microorganism, such as yeast. The conversion may be accomplished
by saccharifying the endosperm with a number of additional inputs,
such as saccharifying enzyme compositions, without cooking the
endosperm. The downstream processes of biorefinery 10 may not
require that corn 12 be saccharified prior to fermentation process
28, although certain benefits and co-products may be enhanced by
saccharification process 26.
[0058] The output of saccharification process 26 may be described
as a fermentation slurry, which may be directed into fermentation
process 28, in which sugars within the fermentation slurry are
fermented to produce ethanol 16. Additional inputs (e.g.,
microorganisms such as yeast) may be introduced into fermentation
process 28 to facilitate the fermenting. The output of fermentation
process 28 may include fermentation product 32, such as a mixture
of ethanol, water, syrup, particulate matter (e.g., fiber, germ,
yeast, etc.), and dissolved solids.
[0059] Fermentation product 32 from fermentation process 28 may be
directed into separation process 50, in which fermentation product
32 is separated into a liquid component (e.g., liquid 62) and a
solids component (e.g., wet solids 64). The equipment used for
separation process 50 may vary and may include, for example,
centrifuges, decanters, hydroclones, sedimentation tanks, and
filter presses.
[0060] Liquid 62 (e.g., water/ethanol mixture) and wet solids 64
(e.g., wet solids) may then be directed into separate processing
paths. Liquid 62 may be directed into distillation system 42; wet
solids 64 may be processed through solids processing system 34. An
end product of the liquids processing path is ethanol 16; an end
product of the solids processing path is meal 18 (and possibly
other bioproducts such as biochemicals).
[0061] Liquid 62 (e.g., water/ethanol mixture) from separation
process 50 may first be directed into distillation pre-treatment
process 44, in which liquid 62 is prepared for further
distillation. Distillation pre-treatment process 44 may include
heating liquid 62 prior to distillation. Distillation pre-treatment
process 44 may also include removing the remaining fractions of
germ and fiber from liquid 62 as bioproducts 14. Once liquid 62 has
been pre-treated by distillation pre-treatment process 44, the
pre-treated liquid 62 may be directed into distillation process 46,
in which water may be removed from ethanol 16. Ethanol 16 from
distillation process 46 may be approximately 190 proof (e.g.,
approximately 95% alcohol). Ethanol 16 from distillation process 46
may then be directed into dehydration/filtration process 48, in
which ethanol 16 is further dried and filtered. Ethanol 16 from
dehydration/filtration process 48 may be approximately 200 proof
(e.g., approximately 100% alcohol). Ethanol 16 from
dehydration/filtration process 48 may be sold for use as a
fuel.
[0062] Wet solids 64 from separation process 50 may first be
directed into a wash process 52, in which wet solids 64 are washed
with various concentrations of ethanol 16 to increase the ethanol
concentration of wet solids 64. The wet solids 64 may then be
directed into separation process 38 and desolventizing process 40,
in which the wet solids 64 may be deliquified, separated, and
desolventized to generate meal 18. By increasing the ethanol
concentration of wet solids 64 in wash process 52, the boiling
point of the liquid component of the wet solids will be decreased,
as will its specific heat and enthalpy (heat) of vaporization,
reducing the energy required to dry (e.g., desolventize) the wet
solids in desolventizing process 40. Wash process 52 and separation
process 38 may be integrated or separate, such that each stage
through wash process 52 and separation process 38 progressively
increases the ethanol content in the wet solids. Ethanol 16 from
separation process 38 and desolventizing process 40 may be used to
increase the ethanol concentration of wet solids 64 in wash process
52.
[0063] FIG. 11 is a block flow diagram of an exemplary embodiment
of biorefinery 10. The processes are substantially similar to those
of FIG. 10 through fermentation process 28. Fermentation product 32
from fermentation process 28 may be directed into distillation
system 42 (e.g., distillation pre-treatment process 44,
distillation process 46, and dehydration/filtration process 48),
where fermentation product 32 is distilled to produce ethanol 16.
Stillage 66 from distillation process 46 may be directed into
solids processing system 34, where stillage 66 may be washed with
ethanol to increase the ethanol concentration of stillage 66,
reducing the amount of energy required by desolventizing process 40
to remove liquids from stillage 66 to produce DDG 54. Solids
processing system 34 may receive the ethanol from distillation
process 46 and/or dehydration/filtration process 48. A certain
amount of ethanol from desolventizing process 40 may be directed
back to solids processing system 34 for further use. An extraction
process 79 may also extract bioproducts 14 from solids processing
system 34. Some biochemicals may be extracted from solids
processing system 34 and directed into distillation pre-treatment
44 for further processing.
[0064] FIG. 12 is a block flow diagram of an exemplary embodiment
of biorefinery 10. The processes are substantially similar to those
of FIGS. 10 and 11 through fermentation process 28. Fermentation
product 32 from fermentation process 28 may be separated by
separation process 50 into a liquid component shown as comprising
liquid 62 and a solids component shown as comprising wet solids 64.
Liquid 62 may be converted into ethanol 16 by distillation system
42 (e.g., distillation pre-treatment process 44, distillation
process 46, and dehydration/filtration process 48); wet solids 64
may be directed into wash process 52, where solids may be washed
with a solvent 68 (e.g., hexane) other than ethanol. Solvent 68 may
be received by wash process 52 from solvent conditioning process
70, which may in turn receive spent solvent from wash process 52,
forming a closed-loop cycle of solvent 68 through wash process 52.
Solvent from solvent-washed wet solids 64 may be removed by
separation process 38 and desolventizing process 40 to produce meal
18. Some of the solvent removed from separation process 38 and
desolventizing process 40 may be directed to wash process 52 for
further use. Solvent conditioning process 70 may also remove an
ethanol/water mixture 71 and direct the ethanol/water mixture 71 to
distillation system 42 (e.g., distillation pre-treatment process
44). Solvent conditioning process 70 may further remove water 72;
extraction process 79 may extract co-products 74. Both
pre-treatment process 44 and wash process 52 may facilitate the
recovery of bioproducts 14 available from the fermentation product
32.
[0065] The individual processes of biorefinery 10 may be highly
synergistic, with each process contributing to efficiencies and
other benefits of other processes. For example, by fractionating
and milling the feedstock into primarily ground endosperm in
fractionation process 78, the downstream processes of biorefinery
10 may be indirectly enhanced. Because primarily fermentable
endosperm is directed into saccharification process 26, only enough
energy to saccharify the endosperm will be required by
saccharification process 26. Energy need not be expended processing
the non-fermentable solids (e.g., germ and fiber) in
saccharification process 26 or in other processes, such as the
operation of distillation system 42. Because the fermentation
slurry from saccharification process 26 consists of primarily
fermentable solids, water, and enzymes, fermentation process 28 may
also be generally more efficient.
[0066] By saccharifying the ground endosperm in saccharification
process 26 without cooking, the amount of heat input into the
ground endosperm may be lower as compared to conventional cooking
processes. Saccharifying the ground endosperm without "cooking"
(e.g., using "raw starch" hydrolysis) may lead to meal 18 having a
different quality than DDG 54 produced by conventional
biorefineries. For example, meal 18 may be higher in protein
values, as well as higher in amino acids (e.g., lysine) and other
biochemicals having different attributes and qualities, than
typical DDG 54.
[0067] Separating a liquid component comprising liquid 62 from a
solids component comprising wet solids 64 in separation process 50
may lead to several benefits downstream of separation process 50.
Because wet solids 64 (e.g., a certain amount of ethanol, a certain
amount of water, syrup, particulate matter, and dissolved solids)
have been substantially removed from liquid 62 (e.g., a
water/ethanol mixture), the distillation equipment of distillation
process 46 will be much less likely to encounter fouling from wet
solids 64, which may otherwise impair the performance of the
distillation equipment, render it less efficient, and/or require
cleaning. The distillation equipment of distillation process 46 may
also be sized smaller because the added mass of wet solids 64 need
not be processed through the distillation equipment. The removal of
wet solids 64 may also lead to the distillation equipment of
distillation process 46 requiring less energy than conventional
distillation equipment.
[0068] The combination of the processes of biorefinery 10 may lead
to overall energy reduction of biorefinery 10, as well as reducing
the temperature to which the products of biorefinery 10 are
exposed. Wet solids 64, stillage 66, meal 18, and DDG 54 may all be
processed by biorefinery 10 without ever experiencing temperatures
above approximately 150.degree. C. Maintaining the temperature
below 150.degree. C. has been shown to reduce the possibility of
degradation of the resulting meal 18 or DDG 54. Reduced degradation
may include color transformation and significant oxidation of
residual starches downstream of fermentation process 28. Using
measurements of the resulting meal 18 or DDG 54, such as neutral
detergent fiber (NDF) measurements, it has been found that
maintaining the temperatures experienced by meal 18 or DDG 54
within biorefinery 10 under approximately 150.degree. C.
significantly reduces the possibility of degrading the resultant
meal 18 or DDG 54. Using these same measurements, it has been found
that maintaining the temperatures experienced by meal 18 or DDG 54
within biorefinery 10 under approximately 100.degree. C. may
further reduce the possibility of degrading the meal 18 or DDG
54.
[0069] FIGS. 13 and 14 are a block flow diagram and a process flow
diagram of an exemplary embodiment of solids processing system 34.
Wet solids components 80 (e.g., wet solids 64 or stillage 66) may
be washed with ethanol 16 to increase the ethanol concentration,
facilitating the reduction of energy required for drying. Wet
solids components 80 may generally comprise wet solids or wet beer
solids. Washing with ethanol may lead to lower drying energy
consumption regardless of whether a liquid component (e.g., liquid
62) and a solids component (e.g., wet solids 64) have been
separated by separation process 50. The ethanol wash may also be
used with wet solids exiting a distillation process, as in existing
plants.
[0070] A stream of ethanol 16 may be introduced into wet solids
components 80. The stream of ethanol 16 may be received from
distillation system 42 or may be received from other sources
internal or external to biorefinery 10. The stream of ethanol 16
may be fed through ethanol feed flow lines 82 into an ethanol
distribution system 84, which applies (e.g., sprays, mists, drips,
deposits, or pours over) ethanol 16 to wet solids components 80 to
increase the ethanol concentration of wet solids components 80.
Although ethanol distribution system 84 is illustrated as a series
of spray nozzles, other means of applying ethanol 16 may be used.
For example, ethanol 16 may be poured over wet solids components
80. Wet solids components 80 will remain generally unperturbed by
the application of ethanol 16. Once wet solids components 80 have
been washed with ethanol 16, liquid 86 (e.g., a mixture of water
and ethanol) from wet solids components 80 may be collected by a
liquid collection 88, such as a tank or collection tray.
Co-products (e.g., zein and xanthophylls) may be extracted from
liquid 86, and liquid 86 collected by liquid collection 88 may be
directed into distillation system 42 for further processing.
[0071] Wet solids components 80 washed with ethanol 16 may be
transformed into wet solids components 90, which contain an
increased concentration of ethanol 16 to water as compared to the
initial wet solids components 80. Less energy may be required by a
desolventizer 40 to dry (i.e., desolventize) wet solids components
90 (e.g., after ethanol washing) than would be required by
desolventizer 40 to dry (i.e., desolventize) wet solids components
80 (e.g., before ethanol washing). The reduction in energy required
to desolventize/dry wet solids components 90 to produce meal 18 may
be due at least in part to the fact that wet solids components 90
contain an increased concentration of ethanol 16 to water as
compared to wet solids components 80.
[0072] FIG. 15 is an exemplary graphical representation 92 of
energy for drying wet solids as it relates to the amount of ethanol
present in the liquid portion of those wet solids. The horizontal
axis in FIG. 15 represents the volume of ethanol present in the
liquid portion of the wet solids as a percent of the total liquid
volume portion of the wet solids. The vertical axis in FIG. 15
represents the amount of energy that it would take to dry (e.g., by
vaporization) all liquid from wet solids. The graphical
representation in FIG. 15 represents the relationship of the amount
of energy to dry the solids within the liquid portion as the
concentration of ethanol changes in the liquid portion of the wet
solids. In a conventional drying process, the wet solids may
contain no ethanol and may require .epsilon..sub.0 amount of energy
to remove the liquid from wet solids. By processing the wet solids
to contain 20% by volume of ethanol, the amount of energy required
to remove the liquid from wet solids would decrease to
.epsilon..sub.20 as depicted in FIG. 15. This trend continues as
the ethanol concentration is increased, as seen when the ethanol
concentration is increased to 90% by volume and the new amount of
energy required to remove the liquid portion is drastically reduced
to .epsilon..sub.90. The lowest amount of energy required to remove
the liquid from wet solids can be achieved when the liquid is 100%
ethanol.
[0073] Returning to FIGS. 13 and 14, increasing the ethanol
concentration of wet solids components 90 decreases the amount of
energy required to dry wet solids components 90 at least partially
because water has a relatively high boiling point, heat capacity,
and enthalpy (heat) of vaporization as compared to ethanol. A
relatively high amount of energy is required to heat water to a
temperature sufficient to vaporize the water; a relatively low
amount of energy is required to heat ethanol to a temperature
sufficient to vaporize ethanol. For example, the boiling point of
ethanol is approximately 173.degree. F. at atmospheric pressure;
the boiling point of water is approximately 212.degree. F. at
atmospheric pressure. The heat capacity of ethanol is approximately
0.58 BTU/lb-.degree. F.; the heat capacity of water is 1.0
BTU/lb-.degree. F. The enthalpy (heat) of vaporization of ethanol
is approximately 362 BTU/lb; the enthalpy (heat) of vaporization of
water is approximately 980 BTU/lb. Ethanol may be heated with less
energy input, reaching its boiling point at a lower temperature,
and once at the boiling point, vaporizes with less energy
input.
[0074] Increasing the ethanol concentration of wet solids
components 90 helps to decrease the amount of energy required by
desolventizer 40 to dry/desolventize wet solids components 90.
FIGS. 13 and 14 include one stage of ethanol washing. FIGS. 16 and
17 are a block flow diagram and a process flow diagram of exemplary
embodiments of solids processing system 34, comprising multiple
ethanol wash stages. Separation process 50 may separate a liquid
component shown as liquid 62 (e.g., a water/ethanol mixture) from a
solids component shown as wet solids 64 (e.g., a certain amount of
ethanol, a certain amount of water, syrup, particulate matter, and
dissolved solids). Liquid 62 may be directed into distillation
process 46, which may produce ethanol 16.
[0075] Ethanol 94 from distillation system 42 may be directed into
a first stage wash 96, which also receives wet solids 64 from
separation process 50. Wet solids 64 from separation process 50 are
washed with ethanol 94 to increase the ethanol concentration of wet
solids 64. It should be noted that when reference is made to
"ethanol" in the discussions of the wash process, the fluid used
may, and in many cases will, be an ethanol-containing fluid, such
as a mixture of water and ethanol. Any other suitable solvent
(e.g., hexane) may also be used. The "wash" fluid will generally
have a higher concentration of ethanol (or other solvent) than the
wet solids receiving the wash, displacing water in the wet solids
with ethanol (or other solvent).
[0076] First stage wash 96 is configured to mix wet solids 64 with
ethanol 94. Ethanol-washed solids 98 from first stage wash 96 may
be directed into a first stage separation 100, which separates
first stage solids 102 from first stage liquid 104. First stage
liquid 104 may consist of a water/ethanol mixture, which may be
directed back to distillation system 42 for further processing.
First stage liquid 104 washes away a certain amount of the water
from wet solids 64. First stage solids 102 output from first stage
separation 100 will have a higher ethanol concentration than wet
solids 64 input into first stage wash 96.
[0077] A second stream of ethanol 106 may be directed into a second
stage wash 108, which also receives first stage solids 102 from
first stage separation 100. First stage solids 102 from first stage
separation 100 may be washed with ethanol 106 to further increase
the ethanol concentration of first stage solids 102. Second stage
wash 108 may be configured to mix first stage solids 102 with
ethanol 106. Ethanol 106 may be received from distillation system
42 or may be received from other processes within biorefinery
10.
[0078] Ethanol-washed solids 110 from second stage wash 108 may be
directed into a second stage separation 112, which may separate
second stage solids 114 from second stage liquid 116. Second stage
liquid 116 may consist of a water/ethanol mixture, which may be
directed back to first stage wash 96. Second stage liquid 116 may
supplement or replace ethanol 94 from distillation system 42 to
wash wet solids 64 in first stage wash 96. Second stage liquid 116
washes away a certain amount of the water from first stage solids
102. Second stage solids 114 output from second stage separation
112 will have a higher ethanol concentration than first stage
solids 102 input into second stage wash 108.
[0079] The ethanol wash cycles (e.g., washing and separating) may
be repeated multiple times. A last stream of ethanol 118 may be
directed into a final stage wash 120, which also receives the
previous stage solids from a previous stage separator. The previous
stage solids may be washed with ethanol 118 to further increase the
ethanol concentration of the previous stage solids. Final stage
wash 120 may be configured to mix the previous stage solids with
ethanol 118. Ethanol 118 may be received from distillation system
42 or may be received from other processes within biorefinery
10.
[0080] Ethanol-washed solids 122 from final stage wash 120 may be
directed into a final stage separation 124, which may separate
final stage solids 126 from final stage liquid 128. Final stage
liquid 128 will consist of a water/ethanol mixture, which may be
directed back to the previous stage wash. Final stage liquid 128
may wash away a certain amount of the water from the previous stage
solids. Final stage solids 126 output from final stage separation
124 will have a higher ethanol concentration than the previous
stage solids input into final stage wash 120.
[0081] Final stage solids 126 may then be directed into an
evaporation stage 130, in which the remaining liquid may be
evaporated from final stage solids 126, leaving dry or
substantially dry meal 18. Ethanol vapor 132 recovered from
evaporation stage 130 may be condensed by a condenser 134 and added
to the final stage ethanol 118 in the final stage ethanol wash
cycle, as shown by line 136. In order to effect the condensation of
ethanol vapor 132 from evaporation stage 130, a heat exchanger may
be used to recover waste heat from any available source, and direct
the heat into evaporation stage 130.
[0082] FIG. 17 is substantially similar to FIG. 16 with additional
wash stages illustrated. A third stream of ethanol 138 may be
directed into a third stage wash 140, which also receives second
stage solids 114 from second stage separation 112. Second stage
solids 114 from second stage separation 112 may be washed with
ethanol 138 to further increase the ethanol concentration of second
stage solids 114. Third stage wash 140 may be configured to mix
second stage solids 114 with ethanol 138. Ethanol 138 may be
received from distillation system 42 or may be received from other
processes within biorefinery 10.
[0083] Ethanol-washed solids 142 from third stage wash 140 may be
directed into a third stage separation 144, which may separate
third stage solids 146 from third stage liquid 148. Third stage
liquid 148 may consist of a water/ethanol mixture, which may be
directed back to second stage wash 108. Third stage liquid 148 may
supplement or replace ethanol 106 from distillation system 42 to
wash first stage solids 102 in second stage wash 108. Third stage
liquid 148 washes away a certain amount of the water from second
stage solids 114. Third stage solids 146 output from third stage
separation 144 will have a higher ethanol concentration than second
stage solids 114 input into third stage wash 140.
[0084] This process continues with a fourth stream of ethanol 150
being used by a next-to-final stage wash 152 to generate
ethanol-washed solids 154, which may be separated by a
next-to-final stage separation 156. Similar to the other wash
stages, solids 158 from next-to-final stage separation 156 may be
directed into final stage wash 120; liquid from next-to-final stage
separation 156 may be directed to the previous wash stage.
[0085] The ethanol wash stages of FIGS. 16 and 17 may be repeated
multiple times such that the wet solids contain a low concentration
of water and a high concentration of ethanol. The number of ethanol
wash stages may be chosen to achieve a particular concentration of
ethanol in the resultant wet solids prior to drying. The
concentration of the resultant wet solids prior to drying may be
selectively adjusted. In each ethanol wash stage, the washes
receive a quantity of ethanol wash containing a higher ethanol
concentration than the concentration present in the wet solids. For
each ethanol wash stage, a water/ethanol mixture may be received
from a subsequent ethanol wash stage as an ethanol wash source. The
water/ethanol mixture from a subsequent ethanol wash stage may be
suitable for a previous ethanol wash stage because the
water/ethanol mixture from the subsequent ethanol wash stage may
generally contain more ethanol than the wet solids of the previous
ethanol wash stage. Using ethanol from a subsequent ethanol wash
stage allows the same stream of ethanol 94 brought into the initial
ethanol wash stage to be used over and over again until the final
ethanol wash stage. If enough ethanol wash stages are used, the
composition of the resulting wet solids will have an ethanol
concentration approximately equal to the ethanol concentration of
ethanol used in the initial ethanol wash stage. After the multiple
ethanol wash stages, the resultant final stage solids 126 contain a
liquid component with a higher concentration of ethanol than wet
solids 64 from separation process 50. In certain embodiments,
ethanol stream 118 may be the only stream of ethanol used; ethanol
streams 94, 106, 138, and 150 may be used as make-up ethanol, to
selectively control the concentration of ethanol in the other wash
stages, or may be omitted.
[0086] Returning to FIG. 15, to minimize the energy to dry meal 18,
the ethanol concentration of the resultant final stage solids 126
may be at or above the azeotropic ratio for water and ethanol
(e.g., point A), which is approximately 96% ethanol-to-water. At
concentration levels at or above the azeotropic ratio, ethanol in
wet solids will vaporize at substantially the same rate as the
remaining water in the wet solids, leaving meal 18 while using the
least amount of energy for drying. With a ratio of ethanol-to-water
below the azeotropic ratio, drying of wet solids will be less
efficient than when the ratio is at or above the azeotropic ratio.
The process may bring the ethanol content of the wet solids to any
point along the concentration line with consequent benefits to
drying. In an effort to achieve certain benefits, the wet solids
will be brought to an ethanol concentration above the azeotropic
ratio.
[0087] Returning now to FIGS. 16 and 17, evaporation stage 130 may
employ a dryer for drying the resultant final stage solids 126,
otherwise referred to as wet cake. The drying process may expose
meal 18 to temperatures just high enough to vaporize ethanol vapor
132 from meal 18. Meal 18 may be altered and change color when
exposed to high temperatures. By limiting the temperature that
final stage solids 126 experience by using a low-energy drying
process, the possibility of altering the meal 18 during evaporation
stage 130 may be substantially reduced. Because final stage solids
126 may be dried at much lower temperatures and with less energy
input than in conventional processes, a large volume of air may not
be required during evaporation stage 130. Because a lower volume of
air may be used in evaporation stage 130 for low-energy drying, the
concentration of liquid in the resulting ethanol vapor 132 may be
relatively high. Ethanol vapor 132 may also be condensed and
re-used within biorefinery 10, reducing emissions from biorefinery
10. Because water used in evaporation stage 130 may be
re-circulated, more of the water initially injected into the
saccharification (if used) and fermentation processes of
biorefinery 10 may be sent back to distillation system 42, where it
may be captured and re-used, significantly reducing the overall
water consumption of biorefinery 10. The specific equipment of
FIGS. 16 and 17 are merely illustrative. Other specific equipment
and processes may be used to implement multiple ethanol wash stages
to increase the ethanol concentration of wet solids for the purpose
of reducing the energy required to dry the wet solids.
[0088] Each stage of the solids processing (including steps in the
wash/separation process) may be conducted on a single apparatus or
(as indicated in FIGS. 16-18, for example) may be conducted on
separate apparatus of the same type or including different types of
apparatus (e.g., a filter belt system, separator, centrifuge,
decanter, etc.); different stages of the processing of the solids
component may be conducted on the same or on different/separate
apparatus. In the processing of the wet solids (e.g. wet cake),
additional operations to the wash/separation process, including
operations such as soaking, re-mixing, slurrying, or other
processing of the solids component may be conducted in various
sequences, before, during or after washing and separating
operations.
[0089] According to an exemplary embodiment, at least a portion of
the solids processing can be conducted on a filter belt system
shown as including filter belt 162 (see, e.g., FIGS. 18 through
24). The filter belt system may include one or more belts (e.g.,
for conveying material), some of which may be comprised of a filter
media (e.g., to allow the filtration of material on and through the
belt), bulk handling systems for loading and unloading the material
into and from the system, controls and other instrumentation. The
filter belt system may be segmented into stages or chambers (some
of which may be configured to operate at differential pressure,
including vacuum or positive pressure). According to other
embodiments, other combinations of systems may be used for solids
processing of the solids component (e.g., wet solids or wet
cake).
[0090] FIGS. 18A and 18B are cross-sectional views of an exemplary
embodiment of an ethanol wash process 160 capable of implementing
multiple ethanol wash stages. Ethanol wash process 160 comprises an
apparatus shown as a filter belt 162 conveyed by a pair of rollers
164, 166. Rollers 164, 166 are configured to rotate in a clockwise
fashion, as shown by arrow 168, causing filter belt 162 to move in
a left-to-right direction from the top of roller 164 to the top of
roller 166, as shown by arrow 170, and in a right-to-left direction
from the bottom of roller 166 to the bottom of roller 164, as shown
by arrow 172. The specific relative movement of filter belt 162 and
rollers 164, 166 may vary among specific implementations.
[0091] Wet solids 64 may be loaded onto the top of filter belt 162
and may move in a left-to-right direction. The left-hand end of
filter belt 162 may be referred to as the upstream end; the
right-hand end of filter belt 162 may be referred to as the
downstream end. Ethanol wash process 160 utilizes a counterflow
ethanol wash process. Ethanol may flow through ethanol wash process
160 from the downstream end of filter belt 162 to the upstream end
of filter belt 162; wet solids 64 may flow through ethanol wash
process 160 from the upstream end of filter belt 162 to the
downstream end of filter belt 162. The ethanol used for ethanol
wash process 160 generally flows in a direction opposite from the
flow of wet solids 64. The ethanol used for ethanol wash process
160 may alternatively flow in the same direction as wet solids
64.
[0092] Ethanol may be introduced into ethanol wash process 160
toward the downstream end of filter belt 162. A first stream of
ethanol 174 may be applied to (e.g., poured over, sprayed onto, or
deposited onto) wet solids 64 by ethanol distribution system 84
above a first downstream collection vessel 176. A mixture of water
and ethanol may be drawn through filter belt 162 by gravity and/or
vacuum into collection vessel 176 or the flow of the mixture of
water and ethanol through filter belt 162 and into collection
vessel 176 may be facilitated by positive differential pressure
above filter belt 162. The water/ethanol mixture 178 from
collection vessel 176 may then be combined with a second stream of
ethanol 180, with the combination being applied to (e.g., poured
over, sprayed onto, or deposited onto) wet solids 64 by ethanol
distribution system 84 above a second downstream collection vessel
182, which is upstream of collection vessel 176. The first stream
of ethanol 174 may have a higher, lower, or substantially similar
concentration of ethanol than the second stream of ethanol 180. In
other embodiments, the second stream of ethanol 180 may not be
combined with the water/ethanol mixture 178 from collection vessel
176, but rather only the water/ethanol mixture 178 may be applied
to wet solids 64. A mixture of water and ethanol may be drawn
through filter belt 162 by gravity and/or vacuum into collection
vessel 182 or the flow of the mixture of water and ethanol through
filter belt 162 and into collection vessel 182 may be facilitated
by positive differential pressure above filter belt 162. The
water/ethanol mixture 184 from collection vessel 182 may then be
applied to (e.g., poured over, sprayed onto, or deposited onto) wet
solids 64 by ethanol distribution system 84 above a third
downstream collection vessel 186, which is upstream of collection
vessel 182.
[0093] Water/ethanol mixture 188 from collection vessel 186 may be
directed toward other upstream ethanol distribution systems 84.
Ultimately, water/ethanol mixture 190 may be applied to (e.g.,
poured over, sprayed onto, or deposited onto) wet solids 64 by
ethanol distribution system 84 above a first upstream collection
vessel 192. Water/ethanol mixture 194 from collection vessel 192
may be directed back to distillation system 42 to recapture some of
the ethanol. A second upstream collection vessel 196 upstream of
collection vessel 192 may collect water/ethanol mixture 198, which
may also be directed back to distillation system 42 to recapture
some of the ethanol. A final downstream collection vessel 200
downstream of collection vessel 176 may collect water/ethanol
mixture 200, which may also be directed back to distillation system
42 to recapture some of the ethanol. Collection vessel 200 may also
act as an evaporation stage, whereby the last remaining
water/ethanol mixture 202 may be removed or joined with the
water/ethanol mixture 178 from collection vessel 176. A separate
drying process, such as evaporation stage 130 of FIGS. 16 and 17
and/or desolventizer 40 of FIGS. 13 and 14 may also be used
downstream of ethanol wash process 160.
[0094] More or less pure ethanol may be applied to wash the wet
solids at the various locations along the filter belt 162. Such
concentrations, along with the flow rates of the wash fluid and the
speed of the filter belt 162, may serve to control the rate of
displacement of water in the wet solids by ethanol. Such factors
may regulate the relative difference in ethanol content at each
wash stage, as well as the ultimate ethanol content of the wet
solids just before final drying.
[0095] FIGS. 19 through 23 are cross-sectional views at various
locations along filter belt 162 of FIGS. 18A and 18B. For example,
FIG. 19 is a cross-sectional view of filter belt 162 of FIGS. 18A
and 18B upstream of the location where wet solids 64 are placed
onto filter belt 162 shown by arrow 204 in FIGS. 18A and 18B.
Although any filter belt technology may be employed, filter belt
162 may have a substantially perforated or porous structure such
that a liquid component of wet solids 64 on filter belt 162 may be
drawn through filter belt 162 or the flow of the mixture of water
and ethanol through filter belt 162 may be facilitated by positive
differential pressure above filter belt 162. Filter belt 162 may
also include a collection tray 206, which may facilitate the
collection of water/ethanol mixtures collected through filter belt
162. Collection tray 206 may include a collection opening 208,
through which water/ethanol mixtures may be collected into
collection vessels. FIG. 20 is a cross-sectional view of filter
belt 162 of FIGS. 18A and 18B at a location where wet solids 64 are
placed onto filter belt 162 shown by arrow 210 of FIGS. 18A and
18B. A vacuum or gravity beneath filter belt 162 may draw a
water/ethanol mixture 212 from wet solids 64 onto collection tray
206 and into collection vessel 196, as shown by arrows 214. FIG. 21
is a cross-sectional view of filter belt 162 of FIGS. 18A and 18B
upstream of ethanol distribution system 84 shown by arrow 216. At
this point on filter belt 162, wet solids 64 will contain a certain
concentration of ethanol. FIG. 22A is a cross-sectional view of
filter belt 162 of FIGS. 18A and 18B at a location near ethanol
distribution system 84 shown by arrow 218. At this point, ethanol
is introduced into wet solids 64 by ethanol distribution system 84,
transforming wet solids 64 into a mixture of liquids 220 (e.g., a
water/ethanol mixture) and solids 222. A vacuum or gravity beneath
filter belt 162 may draw a water/ethanol mixture 212 from wet
solids 64 onto collection tray 206 and into a collection vessel, as
shown by arrows 214. FIG. 22B is a cross-sectional view of filter
belt 162 of FIGS. 18A and 18B at a location near ethanol
distribution system 84 shown by arrow 218. A pressure chamber 223
may be used to create a differential pressure between the top and
bottom of filter belt 162. Pressure may be applied within pressure
chamber 223 to facilitate washing by effectively facilitating the
flow of the ethanol through wet solids 64. Wet solids 64 downstream
of location 218 of filter belt 162 will have a higher ethanol
concentration than wet solids 64 upstream of location 218 of filter
belt 162. FIG. 23 is a cross-sectional view of filter belt 162 of
FIGS. 18A and 18B at a location near collection vessel 200, as
shown by arrow 224. Collection vessel 200 may be used as an
evaporation stage. Heated gas 226 may be applied to wet solids 64
above filter belt 162. A vacuum or gravity beneath filter belt 162
may draw heated gas 226 through wet solids 64 and an ethanol vapor
228 may be collected and further processed to recover ethanol and
other desirable components present in ethanol vapor 228.
[0096] FIG. 24 is a perspective view of another exemplary
embodiment of ethanol wash process 160. Wet solids 64 may be placed
on filter belt 162 at an upstream location with meal 18 exiting at
a downstream location of filter belt 162. An initial collection
vessel 196 may collect water/ethanol mixture 198 without washing,
which may be directed back to distillation pre-treatment process
44. The first stream of ethanol 174 may be applied to wet solids 64
above collection vessel 176. A mixture of water and ethanol may be
drawn through filter belt 162 by gravity and/or vacuum into
collection vessel 176 or the flow of the mixture of water and
ethanol through filter belt 162 and into collection vessel 176 may
be facilitated by positive differential pressure above filter belt
162. The water/ethanol mixture from collection vessel 176 may be
directed into a first conditioning process 230, which may filter
and condition the water/ethanol mixture. A portion of the
ethanol/water mixture may be directed to co-product processing, as
shown by arrow 232; filtered/conditioned ethanol from conditioning
process 230 may be applied to wet solids 64 above collection vessel
182.
[0097] A mixture of water and ethanol may be drawn through filter
belt 162 by gravity and/or vacuum into collection vessel 182 or the
flow of the mixture of water and ethanol through filter belt 162
and into collection vessel 182 may be facilitated by positive
differential pressure above filter belt 162. The water/ethanol
mixture from collection vessel 182 may be directed into a second
conditioning process 234, which may filter and condition the
water/ethanol mixture. A portion of the ethanol/water mixture may
be directed to co-product processing, as shown by arrow 236;
filtered/conditioned ethanol from conditioning process 234 may be
applied to wet solids 64 above previous upstream collection
vessels. Ultimately, a mixture of water and ethanol may be drawn
through filter belt 162 by gravity and/or vacuum into collection
vessel 192 or the flow of the mixture of water and ethanol through
filter belt 162 and into collection vessel 192 may be facilitated
by positive differential pressure above filter belt 162. The
water/ethanol mixture 194 from collection vessel 192 may be
directed to distillation pre-treatment process 44.
[0098] In certain embodiments, the apparatus comprising a filter
belt may include two or more such belts. For example, a first belt
may be used for a first stage of washing with ethanol (or another
solvent), while further filter belts may be used for subsequent
stages. The material conveyed with the belts may be transferred
from one belt to the other as the process progresses. Some
embodiments may include intermediate equipment between filter
belts, such as mixers for creating a slurry with the solvent or
solvent mixture, centrifuges or other separators for performing
some degree of moisture removal, and so forth. The filter belts
themselves may be of any suitable type, including arrangements in
which a semi-permeable belt serves as a substrate used to receive
the solids component, and apparatuses with multiple layers of
belts, support structures, and so forth.
[0099] FIG. 25 is a flow chart of an exemplary embodiment of solids
processing system 34. Separation process 50 may be performed to
separate a liquid component shown as liquid 62 (e.g., a
water/ethanol mixture) from a solids component shown as wet solids
64 (e.g., a certain amount of ethanol, a certain amount of water,
syrup, particulate matter, and dissolved solids). Wet solids 64 may
then be washed with ethanol (e.g., wash process 52). For example, a
solvent (e.g., ethanol) may be added to wet solids 64, as shown by
block 238. Once ethanol has been added to wet solids 64, wet solids
64 may be separated to remove a mixture of water and ethanol from
wet solids 64 (e.g., separation process 38). Wet solids 64 will
contain a higher concentration of ethanol than before wash process
52 and separation process 38. Wet solids 64 may then be
desolventized to remove remaining liquids from wet solids 64 to
produce meal 18 (e.g., desolventizing process 40). In each of
separation process 38 and desolventizing process 40, liquid and
vapor may be captured, as shown by block 240. The liquid and vapor
may be distilled and used as a source of ethanol in wash process
52, as shown by block 242. The liquid and vapor may be re-used by
wash process 52.
[0100] FIG. 26 is a flow chart of an exemplary embodiment of
multiple solids processing system 34 stages. Separation process 50
may be performed to separate a liquid component shown as comprising
liquid 62 (e.g., a water/ethanol mixture) from a solids component
shown as comprising wet solids 64 (e.g., a certain amount of
ethanol, a certain amount of water, syrup, particulate matter, and
dissolved solids). Wet solids 64 may then be washed with ethanol
(e.g., wash process 52). Once ethanol has been added to wet solids
64, wet solids 64 may be separated to remove a mixture of water and
ethanol from wet solids 64 (e.g., separation process 38). Wet
solids 64 will contain a higher concentration of ethanol than
before wash process 52 and separation process 38. Subsequent
ethanol wash stages may be used to further increase the ethanol
concentration of wet solids 64 before desolventizing process 40.
For example, wet solids 64 may be washed again with concentrated
ethanol (e.g., wash process 52). For example, a solvent (e.g.,
ethanol) may again be added to wet solids 64, as shown by block
238. Once ethanol has again been added to wet solids 64, wet solids
64 may be separated again to remove a mixture of water and ethanol
from wet solids 64 (e.g., separation process 38). Wet solids 64 may
contain an even higher concentration of ethanol than before ethanol
wash processes 52 and separation processes 38. Wet solids 64 may
then be desolventized to remove remaining liquids from wet solids
64 to produce meal 18 (e.g., desolventizing process 40). In each of
separation processes 38 and desolventizing process 40, liquid and
vapor may be captured, as shown by blocks 240. The liquid and vapor
may be re-distilled and used in other processes internal and/or
external to biorefinery 10, as shown by block 242. The liquid and
vapor may be re-used by previous wash processes 52.
[0101] Various processes upstream of solids processing system 34
may also lead to significant tangible benefits. For example, FIG.
27 is a process flow diagram of an exemplary embodiment of
fractionation process 78. Exemplary processes are described in U.S.
Patent Application Publication No. 2005/0233030, U.S. Patent
Application Publication No. 2007/0037267, U.S. Patent Application
Publication No. 2007/0178567, and U.S. Patent Application
Publication No. 2007/0202214, each of which is incorporated by
reference. Corn 12 may initially be processed into individual corn
kernels 244, which may be fractionated within fractionation process
78. Each corn kernel 244 may be comprised of endosperm 246, fiber
248, germ 250, and a tip cap 252. Endosperm 246 comprises most of
the starches and proteins available in corn kernel 244 and is used
in fermentation process 28 to generate ethanol 16. Endosperm 246
represents the fermentable solids 58 of corn kernel 244; germ and
fiber represent the non-fermentable solids 56 of corn kernel 244,
which may be withheld from fermentation process 28. Endosperm 246
comprises approximately 80-85% of corn kernel 244 by mass, germ 250
comprises approximately 10-15% of corn kernel 244 by mass, and
fiber 248 comprises approximately 5-10% of corn kernel 244 by
mass.
[0102] Fractionation process 78 prepares corn kernels 244 for
saccharification and fermentation in saccharification process 26
and fermentation process 28. Fractionation process 78 reduces corn
kernel 244 to make starches and proteins within corn kernel 244
more readily available for saccharification and fermentation. For
example, corn kernel 244 may first be fractionated into its
component parts, such as germ 250, fiber 248, and endosperm 246.
Tempered whole corn may be fed into a primary separation stage 254,
which substantially separates corn kernel 244 into components
(e.g., fractions) of endosperm germ 250, fiber 248, and endosperm
246. Primary separation stage 254 may also separate out fiber 248
(e.g., bran) and flour (e.g., comprising a fine powder of endosperm
246) and may direct the remaining components of corn kernel 244
into a secondary separation stage 256. Fiber 248 from primary
separation stage 254 may be processed through a secondary starch
recovery process. The secondary starch recovery process may include
a milling stage, a separation stage, and a mechanical fiber dusting
stage. The milling stage may utilize a pin mill, a hammer mill, a
roller mill, or other suitable mill technology.
[0103] Secondary separation stage 256 may further remove germ 250
from endosperm 246. Germ 250 from secondary separation stage 256
may pass through a secondary refining (or purification) process,
which may include a milling stage and a separation stage. The
milling stage may utilize a roller mill. Grits (e.g., endosperm
246) from the secondary refining process may be passed to a
mechanism for reducing their size, such as a hammer mill, prior to
fermentation.
[0104] Fractionating corn kernel 244 to separate endosperm 246
(e.g., fermentable solids) from germ 250 and fiber 248 (e.g.,
non-fermentable solids) may provide several benefits to processes
downstream of fractionation process 78. For example, using
primarily endosperm 246 in saccharification process 26 may enhance
the efficiency of saccharification process 26 because
non-fermentable solids 56 are generally not involved in
saccharification process 26. The fact that the fermentation slurry
from saccharification process 26 includes primarily endosperm 246,
water, and enzymes may also lead to fermentation process 28 being
more efficient because non-fermentable solids 56 are generally not
involved in fermentation process 28.
[0105] By fractionating corn kernel 244 prior to fermentation, the
levels of proteins (e.g., zein) may be increased. For example,
removing germ 250 and fiber 248 fractions prior to fermentation
process 28 may concentrate proteins in the fermentation slurry
delivered to fermentation process 28. Proteins are generally
isolated in endosperm 246 of corn kernel 244 and fractionation of
protein-enriched endosperm 246 results in concentration of proteins
in residuals from fermentation process 28.
[0106] Endosperm 246 from secondary separation stage 256 may be
directed into a milling process, where endosperm 246 may be milled
and reduced in particle size to prepare the ground endosperm for
saccharification process 26 and fermentation process 28. Endosperm
246 may be reduced using any suitable method, including grinding,
to make starches within endosperm 246 more readily available for
saccharification process 26 and fermentation process 28. The
specific equipment used to grind endosperm 246 may include, for
example, a ball mill, a roller mill, a hammer mill, or any other
type of mill capable of grinding endosperm 246 for the purpose of
particle size reduction. The use of emulsion technology, sonic
pulsation, rotary pulsation, and other particle size reduction
methods may be utilized to increase the surface area of endosperm
246, while also raising the effectiveness of flowing the liquefied
media (e.g., decreased viscosity). The ground endosperm 246 may be
referred to as being or including "raw starch." Grinding endosperm
246 exposes more surface area of endosperm 246 and may facilitate
saccharification process 26 and fermentation process 28.
[0107] Ground endosperm 246 from fractionation process 78 may be
directed into saccharification process 26, in which starches within
ground endosperm 246 may be converted into sugars that may be
fermented in fermentation process 28. FIG. 28 is a block flow
diagram of an exemplary embodiment of saccharification process 26.
Endosperm 246 may be combined in a reaction tank 258 with a
saccharifying enzyme composition 260, water 262, and heat 264 to
facilitate the conversion. The saccharifying enzyme composition 260
may include an amylase, such as an alpha amylase (e.g., an acid
fungal amylase). The saccharifying enzyme composition 260 may also
include glucoamylase. The saccharifying enzyme composition 260 may
also include acid fungal amylase for hydrolyzing raw starch within
ground endosperm 246.
[0108] The term "saccharifying" refers to the process of converting
starches within ground endosperm 246 into smaller polysaccharides
and eventually to monosaccharides, such as glucose. Conventional
saccharification methods use liquefaction of gelatinized starch to
create soluble dextrinized substrates that hydrolyze into glucose.
Saccharification process 26 may be conducted without cooking. The
phrase "without cooking" generally refers to a process for
converting starch to sugars without heat treatment for
gelatinization and dextrinization of starches within ground
endosperm 246. "Without cooking" (e.g., a "raw starch" process)
refers to maintaining a temperature below starch gelatinization
temperatures of ground endosperm 246 such that saccharification
occurs directly from the raw native insoluble starch to soluble
glucose, while bypassing conventional starch gelatinization
conditions. Starch gelatinization temperatures are typically in a
range of 57-93.degree. C., depending on the starch source and
polymer type. Saccharification process 26 may be conducted in a
temperature range of approximately 25-40.degree. C. Exemplary
processes are described in U.S. Patent Application Publication No.
2004/0234649, U.S. Patent Application Publication No. 2005/0233030,
U.S. Patent Application Publication No. 2005/0239181, U.S. Patent
Application Publication No. 2007/0037267, U.S. Patent Application
Publication No. 2007/0178567, U.S. Patent Application Publication
No. 2007/0196907, and U.S. Patent Application Publication No.
2007/0202214, each of which is incorporated by reference.
[0109] Saccharification process 26 may include mixing ground
endosperm 246 with a liquid (e.g., water 262), which may form a
slurry or suspension, and adding a saccharifying enzyme composition
260 to the slurry. The addition of the saccharifying enzyme
composition 260 may occur before or during mixing of ground
endosperm 246 with water 262. Saccharification process 26 may
convert raw or native starch to sugars at a faster rate as compared
to conventional saccharification methods that utilize cooking. The
percentage of ground endosperm 246 to water 262 may be higher as
compared to conventional saccharification methods that utilize
cooking because, unlike conventional processes, saccharifying
ground endosperm 246 without cooking does not include
gelatinization, which increases viscosity.
[0110] Saccharification process 26 may utilize any enzyme sources
suitable for saccharifying starches within ground endosperm 246 to
produce fermentable sugars without cooking. The saccharifying
enzyme composition 260 may include an amylase, such as an alpha
amylase (e.g., an acid fungal amylase) or a glucoamylase. The
initial pH of saccharification process 26 may be adjusted by the
addition of, for example, ammonia, sulfuric acid, phosphoric acid,
or process waters (e.g., stillage or backset, evaporator condensate
or distillate, side stripper bottoms).
[0111] The ability of saccharification process 26 to convert
starches within ground endosperm 246 to produce fermentable sugars
without cooking ground endosperm 246 may provide several tangible
benefits. For example, meal 18 that is ultimately produced by
biorefinery 10 may generally be of higher quality because ground
endosperm 246 is not cooked. Meal 18 produced by biorefinery 10 may
include elevated levels of protein as compared to conventional DDG
54. Meal 18 produced by biorefinery 10 may also include elevated
levels of B vitamins, vitamin C, vitamin E, folic acid, amino acids
(e.g., lysine), and/or vitamin A as compared to conventional DDG
54. Meal 18 produced by biorefinery 10 may also have improved
physical characteristics, such as decreased caking or compaction
and increased ability to flow.
[0112] Fermentation slurry 266 from saccharification process 26 may
be directed into fermentation process 28, in which the sugars
within the fermentation slurry 266 are fermented to produce ethanol
16. FIG. 29 is a block flow diagram of an exemplary embodiment of
fermentation process 28. Exemplary processes are described in U.S.
Patent Application Publication No. 2004/0234649, U.S. Patent
Application Publication No. 2005/0233030, U.S. Patent Application
Publication No. 2005/0239181, U.S. Patent Application Publication
No. 2007/0037267, U.S. Patent Application Publication No.
2007/0178567, U.S. Patent Application Publication No. 2007/0196907,
and U.S. Patent Application Publication No. 2007/0202214, each of
which is incorporated by reference. Fermentation slurry 266 may be
combined in fermentation tank(s) 268 with enzymes 270 and yeast 272
to facilitate fermentation. Fermentation process 28 may be
facilitated by mixing the yeast 272 with fermentation slurry 266
under conditions suitable for growth of the yeast 272 and
production of ethanol 16. Fermentation slurry 266 contains sugars
that have been converted from starches without cooking.
[0113] Any of a variety of yeasts 272 may be utilized as the yeast
starter in fermentation process 28. Yeast 272 may be selected to
provide rapid growth and fermentation rates in the presence of high
temperature and high ethanol levels. The amount of yeast starter
utilized is selected to effectively produce a commercially
significant quantity of ethanol 16 within a suitable time from
(e.g., less than 72 or 144 hours). Yeast 272 may be added to
fermentation slurry 266 by any of a variety of methods known for
adding yeast 272 to fermentation processes. Yeast starter may be
added as a dry batch, or by conditioning/propagating. Yeast starter
may also be added as a single inoculation.
[0114] Fermentation process 28 may be conducted as either a
continuous process or a batch process. As a continuous process,
fermentation slurry 266 from saccharification process 26 may be
moved (e.g., pumped) through a series of vessels (e.g., tanks) to
provide a sufficient duration for fermentation process 28.
Fermentation process 28 may also include multiple stages of
vessels. For example, fermentation slurry 266 from saccharification
process 26 may be fed into the top of a first vessel stage,
partially fermented slurry drawn out of the bottom of the first
vessel stage may be fed into the top of a second vessel stage, and
partially fermented slurry drawn out of the bottom of the second
vessel stage may be fed into the top of a third vessel stage. As a
batch process, fermentation slurry 266 may be directed into a
vessel, where the fermentation cycle may be completed before the
vessel is emptied.
[0115] Output from fermentation process 28 may include the
fermentation product shown as beer 32. Ethanol 16 may be recovered
from liquids in beer 32, meal 18 may be recovered from solids in
beer 32, and other various by-products (e.g., proteins and corn
syrup) may be separated from beer 32. Fermentation process 28 may
generate a relatively large amount of carbon dioxide (CO.sub.2) and
other gases. A system may be installed at biorefinery 10 to
capture, re-use, and/or otherwise dispose (e.g., via sequestration)
of the gases.
[0116] Fermentation product 32 (e.g., beer) may be separated by
separation process 50 into a liquid component (e.g., liquid 62) and
a solids component (e.g., wet solids 64). FIG. 30 illustrates
exemplary embodiments of separation process 50. Liquid 62 may be
directed into distillation system 42, where ethanol 16 may be
produced. By directing primarily liquid 62 to distillation system
42, equipment of distillation system 42 may be less susceptible to
fouling, which is usually caused by solids present when fermented
beer is distilled directly, such as in conventional methods.
Because liquid 62 has substantially fewer solids, occurrences of
fouling may be substantially reduced. With a reduced susceptibility
to fouling, complicated anti-fouling provisions may be unnecessary,
reducing the complexity and cost of distillation system 42. Because
liquid 62 is substantially free of solids components, heat energy
applied to distillation system 42 may only have to heat those
minimal solids dissolved in liquid 62, reducing heat energy
requirements of distillation system 42 compared to conventional
distillation systems, which must heat both the solids and liquid
components of fermented beer.
[0117] Wet solids 64 may be directed into solids processing system
34, where ethanol (or other solvents) may be added to wet solids 64
to decrease the boiling point, heat capacity, and enthalpy (heat)
of vaporization of wet solids 64. The ethanol concentration of wet
solids 64 from separation process 50 may generally be determined by
fermentation process 28, and may typically fall within a range of
10-20% by volume, although ethanol concentrations above and below
this range may also be used. A substantial portion of water will be
removed from beer 32 as liquid 62 and, as such, the boiling point,
heat capacity, and enthalpy (heat) of vaporization of wet solids 64
may be reduced downstream of separation process 50 as compared to
beer 32 upstream of separation process 50. The amount of energy
required to dry/desolventize wet solids 64 (i.e., having a lower
boiling point, heat capacity, and enthalpy (heat) of vaporization)
may be substantially reduced compared to conventional
deliquification/drying systems, which must deliquify and dry
stillage containing higher concentrations of water (i.e., having a
higher boiling point, heat capacity, and enthalpy (heat) of
vaporization).
[0118] By separating liquid components (e.g., liquid 62) from the
solids components (e.g., wet solids 64) of beer 32 prior to
distillation system 42, the favorable physical characteristics of
ethanol may be exploited (particularly the low boiling point, low
specific heat, and low enthalpy (heat) of vaporization of ethanol)
to evaporate liquid matter from wet solids 64, producing meal 18.
Rather than drying stillage that has been processed in a
distillation system and contains little to no ethanol,
ethanol-containing wet solids 64 may be dried using lower amounts
of energy as compared to conventional methods. Separation process
50 may be performed by any suitable separation means including, but
not limited to, a disk-type centrifuge 274, a decanter centrifuge
276, a hydroclone 278, a sedimentation tank 280, or a filter press
282. Indeed, any type of separator capable of separating liquid 62
from wet solids 64 may be used.
[0119] Meal 18 produced by biorefinery 10 may also be reconstituted
into feed at a desired composition to differentiate the product for
various markets. For example, some protein and any extracted
biochemicals or other bioproducts may be re-applied to the
resulting meal to constitute the desired end product. Levels of
protein and other amino acids could be selectively adjusted. For
example, proteins, fats, syrup, oils, lutein, lysine, zein, and
other bioproducts and biochemicals may be selectively combined with
the meal. According to preferred embodiment, processing of the meal
may take place at temperatures that avoid degradation of the meal
itself. The use of such reduced temperatures at all stages of
processing (through the plant) results in a meal that is of a
different quality than conventional DDG (i.e., resulting from a
process employing "cooked" liquefaction). For example, maintaining
the processing temperatures below about 150.degree. C. is believed
to produce a product that is quite distinct from conventionally
processed DDG, and even lower temperatures, on the order of
100.degree. C. (or even lower, at 93.degree. C., 180.degree. F., or
130.degree. F.) are particularly helpful in creating a unique
meal.
[0120] Depending upon the processing, the meal may be referred to
as "corn meal" (particularly when corn is the feedstock),
"distillers meal", "distillers dried meal", "dried distillers
meal", "protein-containing meal", and "corn distillers meal", among
others. When the solids component is subject to the distillation
process, the resulting product may be different still, somewhat
more akin to conventional DDG, although certain benefits of the
processing are nevertheless realized, such as the reduction in
energy utilization in the biorefinery.
[0121] The meal may also be further transformed for particular
product categories and markets. For example, the meal may be
mechanically pressed or extruded into pellets configured for
packaging, transportation, durability, and digestibility. Such
processing may be well suited for producing animal feeds. Within
this category of product, a number of varieties may be formulated
including different ingredients, protein qualities, additives,
sizes, and configurations.
[0122] While only certain features and embodiments of the invention
have been illustrated and described, many modifications and changes
may occur to those skilled in the art (e.g., variations in sizes,
dimensions, structures, shapes and proportions of the various
elements, values of parameters (e.g., temperatures, pressures,
etc.), mounting arrangements, use of materials, colors,
orientations, etc.) without materially departing from the novel
teachings and advantages of the subject matter recited in the
claims. The order or sequence of any process or method steps may be
varied or re-sequenced according to alternative embodiments. It is,
therefore, to be understood that the appended claims are intended
to cover all such modifications and changes as fall within the true
spirit of the invention. Furthermore, in an effort to provide a
concise description of the exemplary embodiments, all features of
an actual implementation may not have been described (i.e., those
unrelated to the presently contemplated best mode of carrying out
the invention, or those unrelated to enabling the claimed
invention). It should be appreciated that in the development of any
such actual implementation, as in any engineering or design
project, numerous implementation specific decisions may be made.
Such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure, without undue experimentation.
* * * * *