US00760l858B2
`
`(12) Ulllted States Patent
`Cantrell et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,601,858 B2
`Oct. 13, 2009
`
`(54) METHOD OF PROCESSING ETHANOL
`BYPRODUCTS AND RELATED SUBSYSTEMS
`
`(75)
`
`I
`
`nven ors:
`t
`
`avi
`re
`an re ,
`a emon ,
`D _d F d C t H L k
`t GA
`(US); David J. Winsness, Alpharetta,
`GA (US)
`
`(73) Assignee: GS Cleantech Corporation, New York,
`NY (US)
`
`4,407,955 A
`4,944,954 A
`
`5,250,182 A
`5’269’947 A
`5,316,782 A
`5,662,810 A
`5,801,140 A
`5,958,233 A
`
`10/1983 Muller et a1.
`7/1990 SHOP et 31,
`
`.
`10/1993 Bento et al.
`12/1993 Bflskfs
`5/1994 Zirnlich, 111
`9/1997 Willgohs
`9/1998 Langley et a1.
`9/1999 Willgohs
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(1)) by 578 days.
`
`5’998’641 A
`6’146’645 A
`6,433,146 B1
`
`12/1999 Ganguli et a1’
`11/2000 Deckers et a1’
`8/2002 Cheryan
`
`(21) Appl.No.: 11/122,859
`
`(22)
`
`Filed:
`
`May 5, 2005
`
`(Continued)
`
`(65)
`
`Prior Publication Data
`US 2006/0041152 Al
`Feb. 23, 2006
`
`Related U.S. Application Data
`
`OTHER PUBLICATIONS
`Singh, et al., “Extraction of Oil from Corn Distillers Dried Grains
`with Solubles”, 1998, Transactions 0ftheASAE, B0l.4l(6), pp. 1175
`and 1176.*
`
`(60) Provisional application No. 60/602,050, filed on Aug.
`17, 2004.
`
`(Continued)
`
`(51)
`
`II1t- CL
`(2006.01)
`CIIB 1/00
`(52) U.S. Cl.
`........................................................ .. 554/8
`(58) Field of Classification Search .................... .. 554/8
`See application file for complete search history.
`References Cited
`U,S, PATENT DOCUMENTS
`
`(56)
`
`:
`2,216,905 A
`2,253,503 A
`2,446,913 A
`2524718 A
`256155029 A
`§:?§i:Zé§ 2
`3,950,230 A
`4,341,713 A
`
`10/1940 Brown et al.
`11/1941 Brown
`8/ 1948 Erlich
`10/1950 Stark
`10/1952 Roster‘
`_
`13/33? 351153?“
`4/1976 Greenfield et al.
`7/1982 Stolp et a1.
`
`Primary Examiner—Deborah D Carr
`(74) Attorney, Agent, or Firm—Cantor Colburn LLP
`
`(57)
`
`ABSTRACT
`
`1
`
`'1 f
`h d
`'
`f h '
`n one aspect o t e invention, a met o recovers oi
`rom a
`concentrated byproduct, such as evaporated thin stillage
`formed during a dry milling process used for producing etha-
`nol. The method includes forming a concentrate from the
`byproduct and recovering oil from the concentrate. The step
`of forming the concentrate may comprise evaporating the
`byproduct. Further, the step of separating the oil from the
`concentrate may comprise using a centrifuge and, in particu-
`lar, a disk stack centrifuge. Other aspects of the invention
`include related methods and subsystems for recovering oil
`fr°mthmS“11age~
`
`16 Claims, 4 Drawing Sheets
`
`Wfil?Sti||lizfi
`‘M-an-nrcalscn-rattan"
`
`cAsE1
`"azronr
`(um
`
`
`
`mm sllllngi
`Yo1MVu1unnI
`n...
`
`an
`31.12
`I)!
`
`an
`
`SOLENIS EXHIBIT 2024
`
`Hydrite v. Solenis, IPRZO15-01592
`
`SOLENIS EXHIBIT 2024
`Hydrite v. Solenis, IPR2015-01592
`
`

`
`US 7,601,858 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`6,761,914 B2
`2003/0093832 Al
`2003/0180415 Al
`2004/0081654 Al
`2004/0082044 Al
`2004/0087808 Al *
`
`7 /2004 Deckers et al.
`5/2003 Szarka et al.
`9/2003 Stiefel et al.
`412004 Schryvers et al.
`412004 Prevost et al.
`512004 Prevost et al. .................. 554/9
`
`OTHER PUBLICATIONS
`
`Yokoyama, et al. "Liquid Fuel Production from Ethanol Fermenta(cid:173)
`tion Stillage" 1986, The Chemical Society of Japan, pp. 649-652.*
`Minowa, T. et al., Oil Production form Buchwheat Stillage by
`Thermochemical Liquefactional, 1993, national Inst. for Resources
`and Environment, Ibaraki (Japan), STN, Abstract, NTIS database.*
`Yokoyama, et al., "Liquid Fuel Production from Ethanol Fermenta(cid:173)
`tion Stillage," 1986, The Chemical Society of Japan, pp. 649-652.
`"Disk Stack Centrifuge Technology," Alfa Laval website, www.
`alfalaval.com, Aug. 3, 2004.
`N. Singh and M. Cheryan, Extraction of Oil from Corn Distillers
`Dried Grains with Solubles, Transactions of the ASAE, 1998, pp.
`1775-1777, vol. 41(6).
`Y. Dote et al., Liquefaction of Stillage from Ethanolic Fermentation
`and Upgrading of Liquefied Oil, Trans. Mat. Res. Soc. Jpn., 1994, pp.
`285-288, vol. 18A.
`
`(No Author Available), "Thermochemical Liquefaction", article by
`Wisconsin Biorefining Development Initiative, www.wisbiorefine.
`org, p. 1-4, undated.
`International Search Report dated Mar. 11, 2008.
`International Search Report dated Aug. 20, 2008.
`Alfa Laval, "NS 934 DD Decanter," PFT00017EN 0207,
`PFT00018EN 0207, PFT00007EN 0207, 6 pags., 1999.
`(No Author Available) "Thermochemical Liquefaction" article by
`Wisconsin Biorefining Development Initiative, www.wisbiorefine.
`org. pp. 1-4, undated, 2004.
`(No Author Available), "Thermochemical Liquefaction", article by
`Wisconsin Biorefining Development Initiative, www.wisbiorefine.
`org, pp. 1-4, undated, 2004.
`Mcintyre, Craig., "Measurement solutions for Ethanol Producers", A
`white paper by Endress+Hauser, Inc., Copyright 2003, pp. 1-10.
`Jacques et al. "The Alcohol Textbook" 3rd Edition, published 1999,
`Part 1 of 4 Parts, 53 pgs.
`Jacques, et al., "The Alcohol Textbook", 3rd Edition, published 1999,
`Part 2 of 4 Parts, 50 pgs.
`Jacques, et al., "The Alcohol Textbook", 3rd Edition, published 1999,
`Part 3 of 4 Parts, 50 pgs.
`Jacques, et al., "The Alcohol Textbook", 3rd Edition, published 1999,
`Part 4 of 4 Parts, 42 pgs.
`* cited by examiner
`
`

`
`U.S. Patent
`
`Oct. 13, 2009
`
`Sheet 1of4
`
`US 7,601,858 B2
`
`Whole Stillage
`"Mechanica I Separation"
`Moisture Content of Distillers Wet Grains:
`
`CASE 1
`"BEFORE"
`65.0%
`
`Solids Concentration in Thin Stillage:
`
`Moisture Concentration in Syrup:
`
`6.70%
`
`80.0%
`
`Total Capacity
`
`·Total Moisture
`
`·Total Solids
`
`Distillers Wet Grains
`GPM
`57.5
`37.4
`20.1
`
`Total Volume
`Moisture:
`Tota! Solid$
`
`GPM
`
`145
`
`118
`
`Lbs/Hr
`
`72,210
`
`58,702
`
`27
`
`13,508
`
`/\
`
`Thin Stillage
`
`Lbs/hr
`28,634
`18,612
`10,022
`
`!e_
`
`65.0%
`35%
`
`Total Volume
`Moisture:
`Oil Content
`
`Solids: !
`
`! Syrup
`
`Total Volume
`Moisture:
`OU Content:
`Solids:
`
`GPM
`87.5
`80.5
`1.1
`5.9
`
`Lbs/hr
`43,576
`40,090
`566
`2,920
`
`.%
`
`92%
`1.3%
`6.70%
`
`Operating Cost (S/hrl
`
`GPM
`35.0
`28.0
`1.1
`5.9
`
`Lbslhr
`17,430
`13,944
`566
`2,920
`
`~
`
`80.0%
`3.2%
`17%
`
`Dried Product· having 10% moisture content (lbs/hr):
`Moisture to Evaporate (lbsfhr):
`ar,inGPM:
`Fuel Required In Dryer (in Decatherms):
`Dryer Operating Cost@ $5.00 Oecathenn ($/hr):
`Product Value ($/hr):
`
`15,009
`31,055
`62.4
`52.4
`$252.22
`$600.36
`
`Fig. 1
`
`

`
`U.S. Patent
`
`Oct. 13, 2009
`
`Sheet 2 of 4
`
`US 7,601,858 B2
`
`Whole Stillage
`"Mechanical Separation"
`Moisture Content of Distillers Wet Grains:
`Solids Concentration in Thin Stillage:
`Moisture Concentration in Syrup:
`GPM
`145
`118
`27
`
`Lbs/Hr
`72,210
`58,702
`13,508
`
`I \
`
`Thin Stillage
`
`CASE1
`"AFTER"
`65.0%
`6.70%
`80.0%
`
`GPM
`87.5
`110.S
`1.1
`5.9
`
`Lbs/hr
`43,576
`.W,090
`566
`2,920
`
`~
`
`92°.4
`1.3%
`6.70%
`
`Evaporator Removes
`26,146
`Lbs/hr of Water, or
`53
`GPM of Water
`$50.98
`OJ>E!raling Cost ($/hr)
`
`GPM
`35.0
`28.0
`1.1
`5.9
`
`Lbs/hr
`17,430
`13,944
`566
`2,920
`
`80.0%
`J.2%
`17%
`
`14
`
`!Total Capacity
`• Total Moisture
`• Total Solids
`
`Distfllers Wet Grains
`GPM
`57.5
`37.4
`
`Total Volume
`Moisture:
`
`TOllll Solids
`
`20.1
`
`10
`
`Syrup (lbs/hr}:
`Moisture:
`Moisture (lbs/hr):
`Oil Content (lblh~:
`
`Solids Comerrt (lbalhr):
`
`l
`
`'
`
`Lbs/hr %
`28,634
`18,612
`10,022
`
`65.0%
`35%
`
`I
`
`Total Volume
`Molswre:
`Oil Content:
`Solids:
`
`i ' ..
`"'~_~ni
`l!f .........
`j;
`;<a
`"<II ..
`Syrup
`Total Volume
`Molswre:
`on Content:
`Solids:
`
`~
`
`16 892
`82.5%
`13,944
`
`28
`2,920
`
`... l.ba/hr
`_O_i_l'_R_e_c_i:>_v_e_r_e_d __ .-lb_,_s_J_h_r_: _ ___,.,
`·535
`$102
`Oil Value ($/hr):
`
`GPM
`1.1
`
`•
`
`/(,
`
`Dried Product· having 10% moisture content (lbs/hr):
`Moisture to Evaporate (lbs/hr):
`or, in GPM:
`Fuel Required in Dryer (in Decathenns):
`Dryer Operating Cost @ $5.00 Decettierm ($/hr):
`Product Value ($/hr):
`
`14,411
`31,115
`62.5
`52.5
`$262.73
`$576.46
`
`Fig. 2
`
`

`
`U.S. Patent
`
`Oct. 13, 2009
`
`Sheet 3 of 4
`
`US 7,601,858 B2
`
`Whole Stillage
`"Mechanical Separation"
`Moisture Content of Distillers Wet Grains:
`
`CASE2
`"BEFORE"
`60.0%
`
`Solids Concentration in Thin Stillage:
`
`Moisture Concentration in Syrup:
`
`3.67%
`
`60.0%
`
`Total Capacity
`
`-Total Moisture
`
`- Total Solids
`
`Distillers Wet Grains
`GPM
`56.9
`34.1
`22.8
`
`Total Volume
`Moisture:
`
`Total Solids
`
`GPM
`
`145
`
`118
`
`Lbs/Hr
`
`72,210
`
`58,702
`
`27
`
`13,508
`
`I\
`
`Thin Stillage
`
`Lbslhr
`28,325
`16,995
`11,330
`
`_%
`
`60.0%
`40%
`
`GPM
`88.1
`83.7
`1.1
`3.2
`
`Lbs/hr
`43,885
`41,707
`566
`1,612
`
`.%
`
`95%
`1.3%
`3.67%
`
`Total Volume
`Moisture:
`Oil Content:
`Solids:
`
`l
`
`: Io
`.-~{)!
`Evaporator Removes
`fl~ 38,440
`lbs/hr of Water, or
`77
`GPM of Water
`$7 4.96
`Operating Cost ($1hr)
`
`- - - - - - - -
`.%
`
`60.0%
`10.4%
`30%
`
`Lbs/hr
`5,445
`3,267
`566
`1,612
`
`Syrup
`
`Total Volume
`Moisture:
`Oil Content:
`Solids:
`
`GPM
`10.9
`6.6
`1.1
`3.2
`
`Dried Product - having 10% moisture content (lbslhr):
`Moisture to Evaporate (lbs/hr):
`or, in GPM:
`Fuel Required in Dryer (in Decatherms):
`Dryer Operating Cost@ $5.00 Decatherrn ($/hr):
`Product Value ($/hr):
`
`Fig. 3
`
`15,009
`18,761
`37.7
`31.7
`$158.41
`$600.36
`
`

`
`U.S. Patent
`
`Oct. 13, 2009
`
`Sheet 4 of 4
`
`US 7,601,858 B2
`
`CASE2
`"'AFTER"
`60.0%
`3.67%
`60.0%
`
`Whole Stillage
`"Mechanical Separation"
`Moisture Content of Distillers Wei Grains:
`Solids Concentration In Thin Stlllage:
`Moisture Concentration in Syrup:
`GPM
`145
`118
`27
`
`Total Capacity
`- Total Moisture
`- Total Solids
`
`Lbs/Hr
`72,210
`58,702
`13,508
`
`/ \
`
`Thin Stillage
`
`Lbs/hr
`28,325
`16,995
`11,330
`
`~
`
`60.0%
`40%
`
`Total Volume
`Moisture:
`Oil Content:
`Solids:
`
`GPM
`88.1
`83.7
`1.1
`3.2
`
`.b!!§!!!r
`43,885
`41,707
`586
`1,612
`
`~
`
`95%
`1.3%
`3.67%
`
`Evaporator Removes
`
`+
`~IJ..1
`.~01iil_·_ .. ··::.r~~- '----"3""s-744""7=-o-=-----~-~-='--~-;_~_~.o_~e-1;_r._o_r __ ,
`""• Syrup
`
`.
`
`f)j -~'
`
`_
`
`$7 4.96
`
`Operating Cost ($/hr)
`
`Total Volume
`Moisture:
`Oil Content:
`Solids:
`
`GPM
`10.9
`6.6
`1.1
`3.2
`
`Lbs/hr
`5,445
`3,267
`566
`1,612
`
`%
`
`60.0%
`10.4%
`30%
`
`Distillers Wet Grains
`GPM
`56.9
`34.1
`22.8
`
`Total Volume
`Moisture:
`
`Totai Solfds
`
`Syrup (lbs/hr):
`Moisture:
`Moisture (lbslhr):
`
`011 Colllent llblhr):
`
`Sol>do Contant {tbs/hr):
`
`4907
`66.6%
`3,267
`
`11
`
`Z8
`1,612
`
`0111Recovered· lbsfhr : ··
`Oil Value $/hr :
`
`.. GPM
`
`.. :Um/hr '
`._.
`.·_,'
`'538
`$102
`
`l +
`
`Dried Product - having 10% moisture content (lbs/hr):
`Moisture to Evaporate (lbs/hr):
`or, in GPM:
`Fuel Required in Dryer (in Decathenns):
`Dryer Operating Cost@ $5.0D Decalhenn ($/hr):
`Product Value (Slhr):
`
`14,411
`18,821
`37.8
`31.8
`$158.92
`$576.46
`
`Fig. 4
`
`

`
`US 7,601,858 B2
`
`1
`METHOD OF PROCESSING ETHANOL
`BYPRODUCTS AND RELATED SUBSYSTEMS
`
`This application claims the benefit of U.S. Provisional
`Patent Application Ser. No. 60/602,050, filed Aug. 17, 2004,
`the disclosure of which is incorporated herein by reference.
`
`COPYRIGHT STATEMENT
`
`A portion of the disclosure of this document contains mate(cid:173)
`rial subject to copyright protection. No objection is made to
`the facsimile reproduction of the patent document or this
`disclosure as it appears in the Patent and Trademark Office
`files or records, but any and all rights in the copyright(s) are
`otherwise reserved.
`
`TECHNICAL FIELD
`
`The present invention relates generally to recovering oil
`and, more particularly, to recovering oil from a byproduct of
`the dry milling process used to form ethanol.
`
`BACKGROUND OF THE INVENTION
`
`Over the past thirty years, significant attention has been
`given to the production of ethyl alcohol, or "ethanol," for use
`as an alternative fuel. Ethanol not only bums cleaner than
`fossil fuels, but also can be produced using grains such as
`corn, which are of course renewable resources. At present,
`approximately sixty-nine "dry milling" plants in the United
`States produce over two billion gallons of ethanol per year.
`Additional plants presently under construction are expected
`to add over four hundred million gallons to this total in an
`effort to meet the current high demand.
`As noted in the foregoing discussion, a popular method of
`producing ethanol is known as "dry milling," and in the
`United States is typically practiced using corn. As is well
`known in the industry, the dry milling process utilizes the
`starch in the com or other grain to produce the ethanol
`through fermentation, and creates a waste stream comprised 40
`of byproducts termed "whole stillage" (which may be further
`separated into products known as distillers wet grains and
`"thin stillage"). Despite containing valuable oil, this whole
`stillage has for the most part been treated as waste and used
`primarily to supplement animal feed (mostly in the form of
`distillers dried grains with solubles (DDGS), which is created
`by evaporating the thin stillage, recombining the resulting
`concentrate or syrup with the distillers wet grains, and drying
`the product to have a low moisture content; see, e.g., U.S. Pat.
`Nos. 5,662,810 and 5,958,233, the disclosures of which are 50
`incorporated herein by reference).
`Efforts to recover the valuable oil from this byproduct have
`not been successful in terms of efficiency or economy. For
`example, one approach involves attempting to separate the oil
`from the thin stillage before the evaporation stage, such as
`using a centrifuge. However, spinning the thin stillage at this
`stage does not produce usable oil, but rather merely creates an
`undesirable emulsion phase requiring further processing.
`Moreover, the volume of thin stillage present is generally 2 to
`10 times greater than the syrup, which requires considerable
`capital to purchase the number of centrifuges required.
`Together, these obstacles make attempts to recover oil from
`thin stillage highly inefficient and uneconomical.
`U.S. Pat. No. 5,250,182 (the disclosure of which is incor(cid:173)
`porated herein by reference) describes the use of filters for
`removing substantially all solids and recovering lactic acid
`and glycerol from the thin stillage without the need for evapo-
`
`2
`ration. Despite eliminating a step in the conventional process,
`the proposal results in a more complicated arrangement
`requiring multiple filtration steps. Wholesale elimination of
`the evaporator in the vast majority of existing plants is also
`unlikely and otherwise uneconomical. Filters, and especially
`the microfiltration and ultrafiltration types proposed in this
`patent, are also susceptible to frequent plugging and thus
`disadvantageously increase the operating cost. For these rea(cid:173)
`sons, the filtration process proposed in this patent has not
`10 gained widespread commercial acceptance.
`Accordingly, a need exists for a more efficient and eco(cid:173)
`nomical manner of recovering oil from a byproduct contain(cid:173)
`ing it, such as thin stillage created during the dry milling
`process used to produce ethanol.
`
`15
`
`SUMMARY OF THE INVENTION
`
`In accordance with one aspect of the invention, a method of
`processing a concentrated byproduct of a dry milling process
`20 for producing ethanol, such as by using com, is disclosed. In
`its most basic form, the method comprises recovering oil
`from the concentrated byproduct.
`In one embodiment, the byproduct comprises thin stillage,
`and the method includes the step of evaporating the thin
`25 stillage to form a concentrate. The recovering step may fur(cid:173)
`ther comprise separating the oil from the concentrate using a
`disk stack centrifuge. Preferably, the recovering step com(cid:173)
`prises: (1) providing the concentrated byproduct at a tempera(cid:173)
`ture of between about 150 and 212° F. and, most preferably, at
`30 a temperature of about 180° F.; and/or (2) providing the
`concentrated byproduct having a pH of between about 3 and
`6 and, most preferably, between about 3.5 and 4.5. Addition(cid:173)
`ally, it is preferred that the concentrated byproduct have a
`moisture content greater than 15% by weight, more prefer-
`35 ably a moisture content greater than 50% and less than 90%
`and, most preferably, a moisture content between about
`60-85%. The step of recovering the oil from the concentrated
`byproduct produces syrup, and the method may further
`include the step ofrecovering oil from the syrup.
`In accordance with another aspect of the invention, a more
`specific method of processing concentrated thin stillage cre(cid:173)
`ated by a dry milling process for producing ethanol, such as
`from com, is disclosed. The method comprises recovering oil
`from the concentrated thin stillage having a moisture content
`45 ofless than about 90% by weight.
`In one embodiment, the recovering step comprises sepa(cid:173)
`rating the oil from the concentrate using a disk stack centri(cid:173)
`fuge. The method may further include the step of drying the
`concentrate after the removing step.
`In accordance with still another aspect of the invention, a
`method of recovering oil from thin stillage is disclosed. The
`method comprises evaporating the thin stillage to create a
`concentrate having a moisture content of greater than 15% by
`weight and less than about 90% by weight. Oil is then recov-
`55 ered by centrifuging the concentrate, preferably using a disk
`stack centrifuge.
`In accordance with yet another aspect of the invention, a
`method of processing whole stillage is disclosed. The method
`comprises recovering thin stillage including oil and solids
`60 from the whole stillage, concentrating the thin stillage includ(cid:173)
`ing the solids, and recovering oil from the concentrate.
`In one embodiment, the step of recovering the thin stillage
`includes using a separator selected from the group consisting
`of a press, extruder, a decanter centrifuge, and a screen cen-
`65 trifuge. The concentrating step may comprise processing the
`thin stillage to a temperature of between about 150 and 212°
`F., a pH of between about 3 and 6, and a moisture content of
`
`

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`US 7,601,858 B2
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`4
`between 30% and about 90%, and ideally about 60-85% by
`weight. Under these process conditions, the disk stack cen(cid:173)
`trifuge is able to separate the oil in usable form from the
`concentrate in an efficient and effective manner, despite the
`relatively high level of solids present (which may be recov(cid:173)
`ered from the centrifuge in a continuous or intermittent fash(cid:173)
`ion, depending on the particular process conditions).
`Besides creating usable oil, the concentrate or syrup recov(cid:173)
`ered from the disk stack centrifuge is considered more valu(cid:173)
`able. This is because the post-evaporation processing to
`recover or remove the oil improves the efficiency of the dry(cid:173)
`ing process used on the combined concentrate syrup and
`distillers wet grains. A stable, flowable product for supple(cid:173)
`menting animal feed results, which thus further complements
`the value of the oil recovered.
`Two examples are presented below to demonstrate the
`efficacy of the above-described method.
`
`EXAMPLE 1
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`3
`less than 90%. The step ofrecovering oil comprises separat(cid:173)
`ing the oil from the concentrate using a centrifuge. The recov(cid:173)
`ering and concentrating steps may be performed in a continu(cid:173)
`ous fashion. The method may further include drying the
`concentrate after recovering oil.
`In accordance with a further aspect of the invention, a
`subsystem for use in a system for producing ethanol by dry
`milling and creating thin stillage as a byproduct is disclosed.
`The subsystem comprises an evaporator for evaporating the
`thin still age to form a concentrate, and a centrifuge for receiv- 1 o
`ing the concentrate and recovering oil therefrom. Preferably,
`the concentrate has a moisture content ofless than about 90%
`by weight, and the centrifuge is a disk stack type.
`Still a further aspect of the invention is a subsystem for use
`in a system for producing ethanol by dry milling and creating 15
`thin stillage as a byproduct. The subsystem comprises an
`evaporator for evaporating the thin stillage to form a concen(cid:173)
`trate and means for recovering oil from the concentrate. In
`one embodiment, the recovering means comprises a centri(cid:173)
`fuge and, most preferably, a disk stack centrifuge.
`Yet a further aspect of the invention is the combination of
`a concentrate formed from thin stillage including oil and a
`centrifuge for removing at least a portion of the oil from the
`concentrate. Preferably, the concentrate has a moisture con(cid:173)
`tent of greaterthan 15% by weight and less than about 90% by 25
`weight, and the centrifuge is a self-cleaning bowl type of disk
`stack centrifuge, a nozzle bowl disk stack centrifuge, or a
`horizontal centrifugal decanter
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`20
`
`Reference is made to FIGS. 1and2 to illustrate schemati(cid:173)
`cally a first example demonstrating the efficacy of the present
`method.
`FIG. 1 represents one technique for processing whole stil-
`lage resulting from dry milling com to create distillers dried
`grains with solubles. The whole stillage leftover after deriv(cid:173)
`ing the ethanol is mechanically separated into distillers wet
`grains (approx. 35% solids) and thin stillage (approx. 6.7%
`30 solids), such as by using a centrifugal decanter. The thin
`stillage is then introduced to an evaporator to create a syrup
`having a moisture content of approximately 80% by weight
`and about 17% solids by weight. The syrup is then recom(cid:173)
`bined with the distillers wet grains, introduced to a drum
`35 dryer, and dried to reduce the overall moisture content to
`approximately 10% by weight. An estimated total value of the
`resulting distillers dried grains with solubles is $600.36 per
`hour.
`FIG. 2 represents the inventive method and a related sub-
`40 system 10 for implementing it. Initial processing of the whole
`stillage is done in the same fashion, and the mechanically
`separated thin stillage is delivered to the evaporator 12 form(cid:173)
`ing part of the subsystem 10. The resulting concentrate or
`syrup having a moisture content of approximately 80% by
`45 weight and a solids content of approximately 17% by weight
`is delivered to a disk stack centrifuge 14, and preferably a
`"solids ejecting" one, such as an Alfa Laval Model No. AFPX
`510, AFPX 513, or AFPX 617 or equivalent device. At an
`infeed rate of approximately 35 gallons per minute, this cen-
`50 trifuge 14 recovers usable oil at a rate of538 pounds per hour
`and produces syrup having a having a moisture content of
`82.5% by weight, but with far less oil in view of the preceding
`recovery step.
`Recombining the syrup (which is substantially free of oil)
`55 from the centrifuge 14 with the distillers wet grains and
`drying in a drum dryer 16 to a moisture content of 10% by
`weight results in a product having a value of$576.46 per hour.
`However, the 538 pounds per hour of oil recovered has a
`product value of approximately $102 per hour. Accordingly,
`60 the total product value using the inventive method is $678.46
`per hour, which is approximately 12% greater than the
`$600.36 per hour product value resulting from use of the
`conventional set-up shown in FIG. 1. Moreover, removal of
`the majority of the oil before the drying step makes the pro-
`65 cess more efficient, and results in an estimated energy savings
`of approximately 10%, or $26.27 per hour. As a result, prod(cid:173)
`uct value per hour ($678.46) less the estimated dryer operat-
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a partially schematic flow chart illustrating the
`processing of co-products formed during the ethanol extrac(cid:173)
`tion process;
`FIG. 2 is a partially schematic flow chart illustrating the
`recovery of oil from a syrup formed by evaporating the thin
`stillage;
`FIG. 3 is a schematic view similar to FIG. 1; and
`FIG. 4 is a schematic view similar to FIG. 2.
`
`DETAILED DESCRIPTION OF THE INVENTION
`
`In accordance with one aspect of the invention, a method
`recovers oil from a byproduct resulting from the production
`of ethanol using a dry milling technique (which is extensively
`described in the above-referenced' 182 patent). The byprod(cid:173)
`uct, known as "thin stillage," is recovered by separating the
`distillers wet grain from the "whole stillage" leftover after
`fermentation is complete. As is known in the art, this
`mechanical separation may be accomplished using a press/
`extruder, a decanter centrifuge, or a screen centrifuge. Mois(cid:173)
`ture is then removed from the unfiltered thin stillage to create
`a concentrate or syrup, such as through evaporation. Advan(cid:173)
`tageously, usable oil is then easily recovered from this con(cid:173)
`centrated form of the byproduct through relatively simple
`mechanical processing, without the prior need for multiple
`stages of filtration or other expensive and complicated under(cid:173)
`takings.
`In one embodiment, oil is recovered from the concentrate
`by passing it through a centrifuge and, in particular, a disk
`stack centrifuge (and most preferably a self-cleaning bowl
`type). Preferably, the concentrate fed to the disk stack centri(cid:173)
`fuge is at a temperature ofbetween about 150 and 212° F. (and
`ideally 180° F.) and a pH of between about 3 and 6 (ideally
`between about 3.5 and 4.5). As a result of the preceding
`evaporation step, the concentrate has a moisture content of
`greater than 15% and less than about 90%, more preferably
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`

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`US 7,601,858 B2
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`5
`ing cost ($236.46 per hour with the 10% savings) and less the
`estimated evaporator operating cost ($50.98 per hour) is
`about $391.02 per hour.
`
`EXAMPLE2
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`6
`evaporating the thin stillage to remove water and form a
`concentrated byproduct; and
`recovering oil from the concentrated byproduct by heating
`and mechanically processing the concentrated byprod(cid:173)
`uct to separate the oil from the concentrated byproduct,
`wherein the concentrated byproduct has a moisture con(cid:173)
`tent of greater than 30% and less than 90% by weight.
`2. The method of claim 1, wherein the mechanical process(cid:173)
`ing comprises separating the oil from the concentrated
`10 byproduct using a disk stack centrifuge.
`3. The method of claim 1, wherein the recovering step is
`performed on the concentrated byproduct at a temperature of
`between about 150 and 212° F.
`4. The method of claim 1, wherein the recovering step is
`15 performed on the concentrated byproduct at a temperature of
`about 180° F.
`5. The method of claim 1, wherein the recovering step is
`performed on the concentrated byproduct having a pH of
`between about 3 and 6.
`6. The method of claim 1, wherein the recovering step is
`performed on the concentrated byproduct having a pH of
`between about 3.5 and 4.5.
`7. The method of claim 1, wherein the concentrated
`byproduct has a moisture content between about 60-85%.
`8. A method of recovering oil from thin stillage, compris(cid:173)
`ing, in sequence: evaporating the thin stillage to create a
`concentrate having a moisture content of greater than 30% by
`weight and less than about 90% by weight; and centrifuging
`30 the concentrate to recover oil.
`9. The method according to claim 8, wherein the step of
`centrifuging the concentrate comprises using a disk stack
`centrifuge.
`10. A method of processing whole stillage, comprising:
`35 recovering thin stillage from the whole stillage, the thin stil(cid:173)
`lage including oil and solids; concentrating the thin stillage
`including the solids to produce a thin stillage concentrate,
`wherein the thin stillage concentrate has a moisture content of
`greater than 30% and less than 90% by weight; and recover-
`40 ing oil from the concentrate by a process consisting essen(cid:173)
`tially of heating and mechanically processing the concentrate
`to separate the oil from the concentrate.
`11. The method of claim 10, wherein the step ofrecovering
`the thin stillage includes using a separator selected from the
`45 group consisting of a press, extruder, a decanter centrifuge,
`and a screen centrifuge.
`12. The method of claim 10, wherein the concentrating step
`comprises processing the thin stillage to a temperature of
`between about 150 and 212° F., a pH of between about 3 and
`50 6.
`
`Reference is made to FIGS. 3 and 4, which illustrate a
`prophetic comparison between one processing method and
`the inventive method. The set-up is essentially the same as
`shown in FIGS. 1 and 2, but a more effective centrifugal
`decanter is used than the one used in Example 1. As a result,
`the syrup introduced to the disk stack centrifuge 14 would
`have a moisture content estimated at 60% by weight. While
`this does not impact the product value figures, the syrup from
`the centrifuge 14 has a moisture content of only 66.6% by
`weight, as compared to 82.5% by weight in Example 1. As a
`result, the cost per hour of drying this syrup when combined
`with the distillers wet grains to achieve an end product having
`a moisture content of less than 10% is only $158.92, or
`approximately 40% less. Assuming a savings in dryer effi- 20
`ciency of 10%, the product value per hour ($678.46) less the
`estimated dryeroperating cost ($143 .03 per hour) and less the
`estimated evaporator operating cost ($74.96 per hour) is
`$460.46 per hour. This represents an approximate 15%
`increase over the corresponding value calculated for Example 25
`1.
`
`As should be appreciated, the above-described method and
`subsystem of the preferred embodiment essentially require
`the addition of a centrifuge downstream of the evaporator in
`the conventional system for processing thin stillage (which
`centrifuge may thus be considered a "means for" recovering
`oil from thin stillage ). Accordingly, instructions on how to
`implement the above-described method (including the opti(cid:173)
`mum process variables) may be provided along with a cen(cid:173)
`trifuge for use in an ethanol plant for forming the novel
`subsystem 10 disclosed herein. Such instructions result in the
`most efficient implementation of the method, as compared to
`the situation where the scientists or engineers at the plant
`must experiment with the centrifuge to determine the opti(cid:173)
`mum process conditions required to achieve a favorable
`result.
`The foregoing description provides illustration of the
`inventive concepts. The descriptions are not intended to be
`exhaustive or to limit the disclosed invention to the precise
`form disclosed. Modifications or variations are also possible
`in light of the above teachings. For example, the syrup recov(cid:173)
`ered from the centrifuge may be evaporated and processed
`again in a further effort to recover oil before drying. More(cid:173)
`over, in addition to a self-cleaning bowl type of disk stack
`centrifuge, a nozzle bowl disk stack centrifuge would work as
`a means for recovering oil from the concentrate, as would a
`horizontal centrifugal decanter (which may be especially
`beneficial when the moisture content of the concentrate is less
`than 50% by weight) or other like devices for separating oil
`from a substance including suspended solids. Moreover, 55
`besides com, the present invention may have utility with any
`other grain used in a dry milling process for producing etha(cid:173)
`nol, such as for example, milo. The embodiments described
`above were chosen to provide the best application to thereby
`enable one of ordinary skill in the art to utilize the inventions 60
`in various embodiments and with various modifications as are
`suited to the particular use contemplated. All such modifica(cid:173)
`tions and variations are within the scope of the invention.
`The invention claimed is:
`1. A method ofrecovering oil from thin stillage, the method
`comprising, in sequence:
`
`13. The method of claim 10, wherein the step ofrecovering
`oil comprises separating the oil from the concentrate using a
`centrifuge.
`14. The method of claim 10, wherein the recovering and
`concentrating steps are performed in a continuous fashion.
`15. The method of claim 10, further including the step of
`drying the concentrate after the step ofrecovering the oil.
`16. Ina method for processing corn to produce ethanol and
`concentrated thin stillage, the improvement comprising the
`step of recovering a product consisting essentially of oil from
`the concentrated thin stillage by heating and mechanically
`processing the concentrated thin stillage to separate the oil
`from the concentrated thin stillage.
`
`* * * * *