Produccion de Etanol Ingles

7/30/2019 Produccion de Etanol Ingles

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D O E / I D / 1 2 0 5 0 - 1

Engineering81Economic Studiesfor Di rect Appl icat ion of Geothermal Energy

ETHANOL PRODUCTION FORAUTOMOTIVE FUEL USAGEQuarterly Report, 2 July - 30 September 1979

BYS.C. MayR.A. StenzelM.C. WeekesJ. Yu

Date Issued - 31 October 1979

Work Performed UnderContract NO. D E - AC 0 7 - 791D12050for th e Idaho Operat ions Off ic e

Bechtel National, Inc .San Francisc o, Califor nia

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DISCLAIMER

This report was prepared as an account of work sponsored by anagency of the United States Government. Neither the United StatesGovernment nor any agency Thereof, nor any of their employees,makes any warranty, express or implied, or assumes any legalliability or responsibility for the accuracy, completeness, orusefulness of any information, apparatus, product, or processdisclosed, or represents that its use would not infringe privatelyowned rights. Reference herein to any specific commercial product,process, or service by trade name, trademark, manufacturer, orotherwise does not necessarily constitute or imply its endorsement,recommendation, or favoring by the United States Government or anyagency thereof. The views and opinions of authors expressed hereindo not necessarily state or reflect those of the United StatesGovernment or any agency thereof.


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DISCLAIMER

Portions of this document may be illegible inelectronic image products. Images are producedfrom the best available original document.


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ABSTRACT

The producti on of ethanol from potatoes, sugar beet, andwheat usi ng geothermal resources at the Raft River areaof I daho i s being evaluated. The south cent ral secti on ofI daho produces approximatel y 18 mi l l i on bushel s of wheat,1 . 3 mi l l i on tons of sugar beet and 2 4 mi l l i on c w t potatoesannual l y. Based on these producti on f i gures, a 20 mi l l i ongal l on/yr ethanol f ac i l i ty has been sel ected as the l argestscale pl ant t hat can be supported with the cur rent agri -c u l t u r a l resources. The pl ant w i l l operate on al l threef eedstocks nominal l y processing potatoes f or f i ve months,sugar beet f or f our months and wheat f or three months ofthe year.The process f aci l i ty w i l l use conventional alcohol technol -ogy uti l i z i ng geothermal f l ui d at a maximum of 280 F as anenergy source. The process f l ow diagrams f or al l threefeedstocks are currentl y being prepared. There w i l l bebasi cal l y thr ee feedstock preparati on secti ons, al though thel i quef action and sacchari f i cation steps f or potatoes andwheat w i l l i nvol ve common equipment. The fermentati on,di sti l l ati on and by-product handl i ng secti ons w i l l be commonto al l three feedstocks.Three geothermal energy extr act i on systems were consideredto accommodate the energy requi rements of the ethanolf ac i l i t y ( f l ashed steam, pressui zed f l ui d and secondaryheat tr ansf er) . Pressuri zed geothermal f l ui d wi th di r ectheat transfer has been sel ected as the usage mode to mini-mize scale deposi ti on. T entati vel y, the geothermal suppl yw e l l s w i l l be l a i d out i n square gr i ds wi th 1/ 4 m i l e spaci ng.The number of wells required w i l l be determined af ter theprocess heat load i s calculated.


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TABLE OF CONTENTS

F i gur es . . . . . . . . . . . . . . . . . . . . . . . . .Tabl es . . . . . . . . . . . . . . . . . . . . . . . . .Sect on

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Page1 I NTRODUCTI ON . . . . . . . . . . . . . . . . . . 1- 12 ETHANOL PRODUCTI ON TECHNOLOGY.

2. 1 Feedst ock Requi r ement . . . . . . . . . .2. 2 Feedst ock Pr eparat i on . . . . . . . . .2. 3 Sacchar i f i cat i on and Fer ment at i on . . . . .2. 4 Anhydr ous Et hanol Pr oduct i on . I . . . .2 . 5 By- pr oduct Pr ocess i ng . . . . . . . . . . .

3 PROCESS FLOW DI AGRAM PREPARATI ON . . . . . . .3. 1 Est abl i shment Pr ocess Condi t i ons and Scope.3. 2 Pr ocess Fl ow Di agr ams . . . . . . . . . .3 - 3 Sugar Beet Pr ocess i ng . . . . . . . . . . .3. 4 Pot at o Pr ocess i ng Descr i pt i on . . . . .3. 5 Wheat Pr ocessi ng . . . . . . . . . . . . .

4 GEOTHERMAL RESOURCE4. 1 Resour ce Ext r act i on and Requi r ement . . . .4. 2 Geot her mal F l ui d Pr oper t i es . . . . .

2- 12- 12- 42- 62- 82- 9

3- 13- 13-23- 23- 193- 29

4- 14- 14- 3

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T A BLE O F C O NTENT S(continued )

Section Page5 CONCEPTUAL DESI GN O F GEOTHERMAL ENERGYGATHER ING, T RA NSFER , AND D I SPOSA L SY STEM . . . .

5.1 W e l l F i e l d D e s i g n . . . . . . . . . . .5.2 B r i n e G a t h e r i n g System . . . . . . . . .5.3 B r i n e D i s p o s al . . . . . . . . . .

6 ECONOMIC FACTORS . . . . . . . . . . . . . . .6.1 G e o t h e r m a l Well C o s t s . . . . . . . . .6.2 C r o o k ' s Property . . . . . . . . . . . . .6 . 3 G l o v e r ' s Prospect . . . . . . . . . . .6.4 E l e c t r i c R a t e s . . . . . . . . . . . . . .6.5 C o o l i n g Water . . . . . . . . . . . . . . .REFERENCES

5-1 5-15-45-4

6-16-1 6-1 6-26-26-2

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FIGURES

Number Page

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W e l l and Pi pel i ne L ocationR a f t River Area . . . . . . . . . . . . . 1-2Block Flow Diagram Sugar B e e t Processing20 MM G al / Y r Ethanol P l ant . . . . . . . 3-720 MM G al / Y r Nominal E thanol Fa c i l i t ySugar Beet Processing - PreliminaryProcess Flow Diagram . . . . . . . . . . 3-820 MM G al / Y r Nominal E thanol Fac i l i t ySugar Beet Processing - PreliminaryProcess Flow Diagram . . . . . . . . . . 3-9Block Flow Diagram Potato Processing20 MM G al / Y r Ethanol P l ant . . . . . . . . 3-2420 MM G al / Y r Nominal E thanol Fa c i l i t yPreliminary Potato Processing

Process Flow Diagram . . . . . . . . . . 3-2520 MM G al / Y r Ethanol F ac i l i tyP r e l i m i n a r y P r o du c t R e c o v e r yPotato Case . . . . . . . . . . . . . . . 3-26Relative Energy C o s t vsBri ne Return Temperature . . . . . . . . 4-2

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. . .

Number

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TABLES

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Scope of Work . . . . . . . . . . . . . . . . . 1- 4Recent Wheat Producti oni n South C entral I daho . . . . . 2-2Recent Sugar Beet Productioni n South C entral I daho . . . . . . . . . 2-2

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Recent Potato Productioni n South C entral I daho . . . . . . . . . 2-3A verage Compositi on of Sugar Beet (Clean) . . . 3-3P ri nci pal Design Bases - Processing 'Sugar Beets . . . . . . . . . . . . . . . 3-5P ri nci pal Design Bases - Fermentation

Sugar Beets . . . . . . . . . . . . . . . 3-14A verage Potato Composition (C l ean). . . . . . . 3-20P ri nci pal Design Bases - Processingpotatoes . . . . . . . . . . . . . . . . . -21P ri nci pal Design Bases -Potato Fermentati on . . . . . . . . . . . 3-22Geothermal Resource Design Bases . . . . . . . 5-2

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Section 1INTRODUCTION

The exi stence of extensi ve geothermal resources i n the UnitedStates represents an untapped potent i al energy source to supple-ment avai l abl e f oss i l f uel s. High temperature geothermal resources(


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T his study i s di vided i nto nine major tasks to --0 Evaluate the avai l abi l i ty of farm products i nthe R a f t River region to produce ethanol .0 Provide the necessary conversion process.0 E stabli sh the conditi ons and avai l abi l i ty ofthe geothermal resource.0 Provi de an economic anal ysi s.0 Determine i nsti tu ti onal requi rements f or com-mercial operati on.

The ni ne tasks, i ncl udi ng al l of the subtasks, are shown i nTable 1-1.

The study was begun on J ul y 2, 1979. T hi s report covers resul tsaccompl i shed from the inception of the project to the l as t weekof September 1979.

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Table 121SCOPE OF WORK

Task 1 Define Current Ethanol Production Technology1.1 Feedstock Requirement1.2 Feedstock Preparation1.3 Sacchari f i cati on and Fermentation1.4 Anhydrous Ethanol Product on1.5 By-product Processing

Task 2 Process Flow Diagram Preparation2. 1 Establish Process Condi ti ons and Scope2.2 Prepare A l ternative PFD's f or Selected Feedstocks2.3 E stabl i sh Process Requirements '

Task 3 Defini t ion of Geothermal Resource Requirements3.1 Process Conditions3.2 Establ i shment of Geothermal Bri ne Flow Requirements3.3 Study of Physi cal and Chemical C onstrai nts

Task 4 Conceptual Design of Geothermal Energy Gatheri ng Transf erand Disposal Systems4 . 1 W e l l F i el d Design4.2 B ri ne Gatheri ng System4.3 Energy E xtract i on System4.4 Bri ne Disposal4.5 Resource Property V ari ati ons4.6 System Optimization

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Tabl e 1- 1(cont nued )

Task 5 Concept ual Des i gn of Al cohol Fac i l i t y5. 1 Def i ni t i on of Over al l Fac i l i t y5.2 Prepar at i on of Pr ocess Equi pment Speci f i cat i ons5. 3 Est abl i sh Fac i l i t y and Equi pment Li s t s

Task 6 Econom c Anal ys i s of Geot her mal - Al cohol Scheme6. 1 Capi t al Cos t Es t i mat e6. 2 Oper at i ng Cost Anal ys i s6 . 3 Econom c Eval uat i on and Compar i son wi t hOt her Ener gy Sour ces

Task 7 I mpl ement at i on Pl an f or Demonst r at i on Fac i l i t y7 . 1 Def i ne Pr ogr am Goal s7.2 I nf or mat i on Tr ans f er7 . 3 Techni cal Demonst r at i on

Task 8 Si t e I ns t i t ut i on Requi r ement f or Demonst r at i on Pr oj ect8.1 Feeds t oc k Avai l abi l i t y8. 2 Envi r onment al Ef f ect s8. 3 Resour ces Leasehol d Ar r angement8.4 Pr ocedur al Cons i der at i ons

Task 9 F i nal Repor t

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Section 2ETHANOL PRODUCTION TECHNOLOGY

2.1 Feedstock RequirementWheat, sugar beets and potatoes were selected as thecandidate raw materials f o r ethanol f ermentati on. Overthe past few years (1975-1978), producti on of each ofthese crops i n the counties around the R a f t River Geo-thermal P roj ect has been suf f i ci ent to support a "commer-cial-scale" ethanol producti on f a c i l i t y (20 MM gal/yr orlarger). The fol l owi ng shows the average annual production:

0 Wheat (wi nter) 10,000,000 bushel s0 Wheat ( spr i ng) 8,000,000 bushel s0 Sugar beets ' 1,300,000 tons0 Potatoes 24,000,000 c w t .

T abl es 2-1, 2 - 2 , and 2-3 summarize the approximate producti onby counties. T hese quanti ti es cannot be considered as theresources avai l abl e solely for ethanol production. Onecannot introduce a new demand equi val ent to the exi st i ngdemand for these agri cul tural products wi thout seri ousl yupsetting the local market condi ti ons. I n order to obtainraw materials at a reasonabl e price, the total demandmust be kept close to the achievabl e producti on i n the area.About 40 percent of the total cropl and i n these f i ve counti esi s used f o r these three crops. Other cropland acreage

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Table 2-1 (Ref. 2 )Recent Wheat Productioni n South C entral I daho

County Winter Wheatacreage y i el d productionpl anted bu/ac. MM bu

Cassin 60,000 46 2.76J erome 15,000 76 1.14Tw i n F a l l s 20,000 66 1.32Powers 125,000 34 4.25Min idoka 10,000 70 .7

Totals 230,000 44.2 avg 10.17

Spri ng Wheatacreage y i el d productionpl anted bu/ac. MM bu

35,000 71 2.4816,000 69 1.1022,000 75 1.6520,000 76 1.5 240,000 45 1.8133,000 64.3 avg 8.55

Table 2- 2 (Ref. 2 )Recent Sugar Beet Productioni n South Central I daho

County acreageplantedCassin 17,000J erome 5,000Minidoka 30,000Twin F al l s 14,000Power 8,000

Totals 74,000

y ie l dtons/ac.1 81 81 82016.518.2 avg

productiontons306,00040,000540,000280,000132,000

1,348,000

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Table 2-3 (Ref. 2 )Recent Potato Productioni n South Central I daho

County

CassiaJ eromeMinidokaTwin F a l l sPowerTotals

acreagepl anted25,00015,00035,00019,00016,000

110, 000

y ie ldcwt/ac245265235300235225 avg

productionc w t6,125,0003,975,0008,225,0002,700,0003,760,000

24,785,000

coul d be used to i ncrease production, however i r r i gati onwater i s i n l i mi ted supply. Rather than attempt to markedlyi ncrease the production of one of these potent i al f eedstocks,the strategy should be to seek a f racti on of each crop'sannual production f or f eedstock and to work wi th the growersassoci ati ons to ensure that there w i l l be adequate suppl i esf or al l the buyers.

T hi s mul ti -crop f eedstock concept has been adopted f or t h i sstudy.capacity was sel ected as being the l argest scale than canbe supported by the agr i cu l tural resources of the southcentral area. The f aci l i ty would nominall y process potatoesf or f i ve months, sugar beets f or f our months and wheat f orthree months of the year.

A 20 m i l l i o n gal l on per year ethanol production

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I n each year, crop producti ons and prices would dictatethe actual processing mi x and run durati on so that thelowest cost (per gal l on of producti on) f eedstock wouldbe purchased on the open market. Sugar beet acreagewould be contracted f ar i n advance through the growersassociation, so the process run on sugar beets i s essen-t i al l y f i xed before planting t i m e .

Only agri cul tural resources i n the south central area ofI daho were considered. T here i s very l i t t l e productionof wheat, sugar beets and potatoes i n the Utah counti esj u s t south of the Idaho-Utah state l i ne. Truck shipmentof these materi als from other producing areas i n I daho andperhaps Oregon would add too much to the cost of the materia-sto be an economic al ternat i ve.

2.2 Feedstock P reparati onFeedstock preparati on technology f or wheat, sugar beets andpotatoes was di scussed wi th conventional processors (millers,sugar f actor i es, star ch pl ants and dehydrators) wi th equip-ment vendors and wi th s ac char i f i c at i on/ f er ment at i on experts.

For each of the three feedtocks there are basical ly t w opreparati on approaches: 1)whole product processing and,2 ) ref i ned product preparati on. The second, and moreco st l y approach, produces cl ean substrate material whichi s theor eti cal l y amenable to continuous fermentati on.

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Whole product processing i s conducive onl y to batch fermen-tation.schemes were chosen. Both requi re l i quef acti on andsacchari f i cati on steps pri or to fermentati on. F or thebeet case, a' par ti al l y ref i ned product preparati on schemew as selected, si nce there i s l i t t l e experi ence wi th fermen-tati on of the whole beet ( j u i c e and pulp) .

For wheat and potatoes whole product processing

The preparati on steps f or wheat w i l l tentatively consistof cl eani ng, then dry gri nding wi th no separation fol lowedby sl urryi ng wi th water to a starch-dry sol i ds ( D S ) contentsui tabl e f or f ermentation to produce approximatel y 10%ethanol . The pH of the sl ur ry i s adjusted to 6.5 i npreparati on f or gel ati ni zati on and enzymatic l i quef acti on.

Potatoes are washed wi th water, drained and di si ntegratedwi thout peel i ng. The ground potatoes are centrifuged to aDS content of 2 1 percent. The pH i s adjusted to 6.5 as i nwheat preparati on prior to gel ati ni zati on and l i quef action.

Sugar beets are processed using conventi onal beet-sugartechnology. The beets are washed wi th water, drained, slicedinto thin strips (cossettes) and then the j u i c e phase i sextracted from the insol uble porti on of the beets ( pulp) i na hot water di f f usi on process. The thi n j u i c e contains about1 4 percent sucrose and i s par ti al l y concentrated bef ore f er-mentati on to ethanol . These feedstock preparati ons i nvolvesimple, wel l - establ i shed, physi cal processes.

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The r ef i ned pr oduct appr oach i nvol ves convent i onal separ a-t i on pr ocesses whi ch pr oduce hi gh qual i t y st ar ch ( wheat andpot at oes) and l ow i mpur i t y , concent r at ed j ui ce ( beet s ) .The maj or by- pr oduct mat er i al s ar e pr oduced i n t he pr epar a-t i on s t eps r at her t han i n t he post - f er ment at i on pr ocess i ng.

I n or der t o m ni m ze t he cost of t he t hr ee f eedst ock pr ep-ar at i on sec t i ons i n t he f ac i l i t y, t he s i mpl er appr oach wass el ec t ed f or t hi s s t udy.

2 . 3 Sacchar i f i cat i on and Fer ment at i onBot h pot at o and wheat st ar ches must be conver t ed i nt of er ment abl e sugar s. Enzymat i c sc hemes wer e sel ect ed f or

l i quef ac t i on and sacchar i f i cat i on based on st ar ch conver -s i on l i t er at ur e and di scuss i ons wi t h enzyme pr oducer s.The pr ocess i ng condi t i ons se l ec t ed ar e wel l - es t abl i shedand t he amyl ase enzymes r equi r ed ar e commer ci al l y avai l abl e.Pr ocess i ng st eps f or wheat and pot at o st ar ch are near l yi dent i c al so t he same equi pment can be used f or bot h:

0 Addi t i on of t he l i quef yi ng enzyme ( al pha amyl ase)t o t he r aw s t ar ch s l ur r y.0 Cook i ng t he s l ur r y to l i ber at e t he s t ar ch mol ecul es

( gel at i ni z at i on) and to al l ow enzymat i c br eakdownof t he s t ar ch bonds ( l i quef ac t i on) .0 Cool i ng t he sl ur r y and pH adj ust ment t o 4. 5.0 Conver s i on of s t ar ch t o gl ucos e ( s acchar i f i cat i on)by addi t i on of t he sacchar i f y i ng enzyme ( gl uco-amyl ase) and hol di ng t he sol ut i on f or about 48 hour s.

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The sacchar i f i cat i on s t ep can be car r i ed out s i mul t a-neousl y wi t h f er ment at i on wi t h t he penal t y of a hi ghergl ucoamyl ase dose. A c l ean subst r at e i s des i r abl e.

Bot h bat ch f er ment at i on and cont i nuous f er ment at i on sc hemeswer e consi der ed i n t he pr ocess of se l ect i ng pr epar at i onst eps f or each f eed mat er i al . Cont i nuous f er ment at i on of f er st he advant ages of hi gh f er ment at i on r at es ( l ow r es i dence t i me)and l o w yeas t makeup r equi r ement s. I t r equi r es a c l ean sub-s t r at e. Cont i nuous f er ment at i on i s al so mor e suscept i bl e t ocont am nat i on t han t he convent i onal bat ch pr ocess. The bat chf er ment at i on appr oach was chosen al ong wi t h t he whol e pr oductpr ocessi ng appr oach because of i t s r el at i ve s i mpl i c i t y andi t s pr oven r el i abi l i t y.

Bat ch f er ment at i on consi st s of chargi ng a f er ment at i on t ankwi t h t he sugar ( gl ucose o r sucr ose) sol ut i on, addi t i on ofbr ewer s yeast and nut r i ent s and hol di ng t he mash f or about48 hour s to al l ow compl et i on of t he sugar conver s i on t oet hanol . Cool i ng i s r equi r ed t o r emove t he heat of r eact i on,mai nt ai ni ng t he mash t emper at ur e at about 30 C. By- pr oduct sof t he r eac t i ons i nc l ude y eas t , car bon di oxi de, f us el oi l s( hi gh- mol ecul ar wei ght al cohol s) and al dehydes.

Af t er t he f er ment at i on per i od, t he t ank i s empt i ed, cl eanedand s t er i l i zed and i s r eady t o r ecei ve anot her char ge ofsugar sol ut i on. Mul t i pl e f er ment at i on t anks ar e empl oyed

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to avoid enormous tank sizes and to reduce the total cyclet i m e - f i l l , ferment, empty and cl ean.

The sugar so l ut i ons from beet and potato processi ng havelower than desi red sugar contents f or optimum fermentati onand the subsequent di st i l l ati on . Prior to f ermentati onboth w i l l be concentrated to be equival ent to the sugarcontent of the wheat processing sol uti on.

2 . 4 Anhydrous Ethanol Producti onThe possi bi l i ty of producing a 190 proof ethanol f or blend-ing with gasoline w as abandoned ear l y i n t h i s study bymutual agreement wi th DOE' S T echnical R epresentati ve.

The fol l owing di st i l l ati on methods f or producing anhydrous200 proof ethanol were subsequentl y examined:

0 Conventional l o w pressure str ipping, rect i f i cat ionand benzene-water-ethanol azeotropic d i s t i l l at ion.0 V acuum d i s t i l l a t i o n to avoid the water-ethanolazeotropi c condi ti on.0 Extracti ve di st i l l at i on with gasol i ne to di rec t l yproduce a gasoline/alcohol mixture.0 D i sti l l ati on fol l owed by vapor phase dehydration

using adsorpti on agents.The last t w o schemes of f er promise of si gn i f i cant energysavi ngs but are rel ati vel y undeveloped processes. V acuumdi sti l l at i on does not appear t o yi el d real cost/energysavi ngs because of the greater investment i n di st i l l ati on

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equipment. K atzen (Ref. 1) of fe rs a dual -pressure di sti l -modi f i cation of the conventional process. However, itrequires a steam temperature (from coal - f i red boi l ers) thati s considerabl y higher than that avai l abl e from the geo-

The more conventi onal scheme was therefo re selected:0 A beer s t i l l producing a 73 mole percent ethanoloverhead and a st i l l age bottoms product wi th f uselo i l s taken of f as a si de draw.0 A benzene-water-ethanol azeotropi c di st i l l ti on wi th

anhydrous ethanol as bottoms product. Water from thebenzene st r i pper i s essent i al l y f r ee of benzene andethanol .2.5 By-product Processing

By-product type and quant i ti es were consi derations i n thesel ecti on of the preparati on schemes f or each f eedstock.Ref i ned product preparati on produces a number of di f f erentf ront-end by-products. Wi th a multi ple feedstock f aci l i ty ,the handl i ng, stor age and marketing of a number of di f f erentby-product materials may not be attracti ve, even i f somehigh-value materials such as gl uten are produced. Processcomplexi ty and low ut i l i za t i on of process equipment arereal drawbacks.

The whole processi ng approach carries the non-fermentables(except f or beet pulp) through the process to the beer s t i l l .The whole st i l l age from each feed material contains y east,other i nsol ubl es and di ssolved so l i ds from which a si ngl e-

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type of by-product-animal-feed would be recovered. I tsadvantage i s a si ngl e recovery scheme that accommodateseach f eedstock .

Production of a w e t by-product f or animal f eeding onsi tewas an opti on considered br i ef l y. While i t would produce aconsi derable energy savi ngs by reducing dryi ng requirements,the opti on adds complexity by i ntroduci ng another i ndustryi nto the area. The feedl ot opti on may not be pr act i cal i nthe geothermal resource si te area.

The by-product processi ng scheme sel ected invol ves:

0 C entri f ugal separation of whole s t i l l age i n to asl udge and a thin l i quor contai ning the dissolvedsol ids.0 Evaporation of the thi n l i quor to a syrup-l ike

product.0 Bl ending the syrup wi th the sludge and dryi ng itwi th geothermal f l ui d as the heat source.0 Grinding the dry so l i ds f or storage and sale asdry animal feed.

Three separate dry products coul d be produced or they couldbe blended f or sale as a si ngl e product.

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Sec t i on 3PROCESS FLOW DI AGRAM PREPARATI ON

3. 1 Est abl i shment Pr ocess Condi t i ons and ScopeThe pr ocess condi t i ons f or t he t hr ee f eedst ock have beengener al l y es t abl i shed. F i nal condi t i ons f or wheat pr oces -s i ng ar e subj ect to conf i r mat i on by a t est bei ng conduct edat Novo Labor at or i es . Ther e wi l l be bas i cal l y t hr ee f eed-s t ock pr epar at i on sect i ons , al t hough the l i quef ac t i on andsacchar i f i cat i on s t eps f or wheat and pot at oes wi l l i nvol vecommon equi pment . The f er ment at i on, di st i l l at i on and by-pr oduct handl i ng sect i ons wi l l be common to al l t hr eef eedst ocks. A desi gn r at e of 2540 gpm of et hanol wi l l bepr oduced f r om t he f er ment at i on st ep. Twent y m l l i on gal l onsper year of 199O pr oof et hanol wi l l be recover ed.

Ut i l i t y r esour ces assumed t o be avai l abl e f or t he pr oces-s e s are:El ect r i c Power 4. 16 kV, 3@, 60 Her t z att he pl ant f enc e l i neCool ng wat er 60 F sour c e f r om wel l sPr ocess wat er 60 F s our c e f r om wel l sPot abl e wat er 60 F sour c e f r omwel l sHot wat er ( max. t emp. ) 280 F geot her mal wat er

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3.2 Process Flow DiagramsThe process f low diagram f or each feedstock are i n var iousstages of preparati on. T he fol l owi ng secti ons provi de thestatus of the sugar beet processi ng and potato processi ngprocess flow diagrams at the end of the report period.

3.3 Sugar Beet ProcessingSugar beets are processed f our conti nuous months each year,November through February, fol l owi ng 3 months of wheatprocessi ng. Three hundred twenty-one thousand tons ofbeets are recei ved by the pl ant f o r cleani ng and processing.On-site storage capacity i s 120,000 tons. About 21,000 tonsof trash and s i l t are removed i n cl eani ng the beets overthe four-month period. The dai l y s l ice contains 442 tons ofsugar of which 432 tons are extracted as a thi n ju i ce inthe di f f usi on process. The thi n j ui ce (13.85% sugar) i sconcentrated to 19%sugar. These 442 tons y i el d a net of213.1 tons of ethanol (ca 91.6% net yi el d) at the end ofbatch f ermentati on of the concentrate j ui ce. T he beer(10.3% w t ethanol ) i s d i s t i l l e d to a 87% w t ethanol over-head product, then dehydrated to a 99.2% w t ethanol producti n a benzene-water-ethanol column. Beet pulp from thedi f fus ion step i s dewatered and dr i ed f o r by-product sale.The whole s t i l l age from the beer s t i l l i s evaporated to asyrup and dri ed wi th the beet pulp. Fusel o i l s (highermolecul ar weight al coho l s) are also recovered as a by-product which may be blended wi th the ethanol product.

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Design BasisT able 3-1 presents the assumed composition of the sugar beetsprocessed i n the pl ant.

TableAverage Compositi on o

3-1Sugar B e e t (Clean)

Soluble dry matterMarcWater

J U I C E

SucroseN-free organi cs (carbohydrates, acids, saponins)N-organics (betai ne, amides, amino acids, puri nes,pyramidines, ammonia and ni t r at es )I norganics ( K , C a, Mg, N a, PO4, C1, SO4)Water

MarcI nsoluble pectic material, protei ns, saponinsCel lulose, l i gni n, hemi cel l ulosesBound water

18.87%5.00%

76.13%100. 00%

16.00%1.20%1.17%

50%76.13%

1.25%1.25%2.50%

100. 00%

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The as-del i vered beets are assumed to contain a tota l ofseven percent (on a clean beet basi s) f oreign matter --rocks, trash and s i l t . I n cl eaning the beets al l foreignmatter i s removed and 0. 1 percent of the soluble dry matterhalf sucrose) i s assumed to be lost i n washing ( or i n storage).

Beets are processed 24-hrs per day, seven days per weekat a design stream f actor of 90 percent - 2769.44 tons perstream day or 2492.5 tons per day on a cal endar day basi s.T ables 3-2 and 3-3 summarize the pr i nc i pal design bases f oreach process secti on.

Each sect i on i s descri bed below. F i gure 3-1 i s an overal lblock diagram of the beet processi ng and F i gure 3-2 i s aprocess flow diagram of the steps up to d i s t i l l a t i o n .F i gure 3-3 shows the product recovery section.B e e t Recei vi ng and Storage -- Sugar beets are shipped tothe ethanol f ac i l i ty by end-dump tr acto r - tr ai l ers. Thenet load averages 25 tons. T rucks are weighed i n ( gross)and o u t (tare) to record the as recei ved tonnages.A t the scale trucks are di rected to one of t w o dump stations,one f or di r ect processi ng and the other f or t r ansf er tostorage. F i ve trucks per hour are routed to the di rectprocessi ng stati on where a hydraul i c dump pl atform el evatesthe trucks to di scharge the beets i nto the w e t hopper.

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T able 3-2PRINCIPAL DESIGN BASES - PROCESSING

SUGAR BEETS

E l evation and N orm a l A tmospheri c Pressure

Beet Receivins ti StoraseReceiving peri odsCarrierL oads per dayDirect processR e c l a i m from storageMaximum reclaim rate

Beet WashingFlume waterWash waterDirect recyclePond recycleL o s t to sludge

4800-ft; 12.24 psia

dayl i ght hours, 7-days per week25-ton net tractor-trailers (end dump)214 for 60 days max rate1235 tpd1728 tpd150 tph

2000 .gal/ ton of ' beets f lumed (desi gn)400 gal /ton of beets (desi gn)60 percent (desi gn)19 percent (maximum)1 percent (minimum)

Beet S1 i c ingS l i c e rate 924 tpd per machineCompressed ai r to slicers 30 lb/ton of beets sl i cedKni fe block cycle t i m e 4 hours(cleaning)

DiffusionA verage di f f usi on temp.DraftL ength of cossettesDiffuser constantDiffusion t i m eSugar i n pul pSugar i n sliced beetsDi f fuser capacity

7OoC + 273' = 343O K120 l b j uice/100 l b cossettes13 m/lOO-g. cossettes6 . 6 x 1064 min..3529% w t (1.237% w t on pul p)15.95% w t3200 tpd

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Table 3-2 (conti nued)PRINCIPAL DESIGN BASES - PROCESSING

SUGAR BEETS

Pulp DewateringR aw pulp moi stureScreened pul p moi sturePressed pul p moi stureSugar l os s i n pulpPress water returnU t i l i t y and Energy R equirements

Electric power

Process waterCooling waterH o t geothermal waterGeothermal steam

Thin J ui ce ConcentrationSucrose ex i t concentrati onNumber of e f fec tsHeat recovery

93%w t85% w t80%w t80% on raw pulp2.237% w t on pul p

to be determined

19.8 percent weightpreheati ng, water heatingand di f f user heati ng

2

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J OB 13412


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* I I I

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A t the other dump stati on beets are dumped i nto a dryhopper and f ed onto a pi nch- rol l er trash screen whichremoves weeds and l eaves. A travel i ng- stacker conveyortransf ers the beets to one of t w o paral l el storage pi l es.A transverse slewi ng boom i s used to stack the beets upto a hei ght of twenty f eet and to a width of 115 feet.A t f u l l capaci ty, each pi l e w i l l contain 60,000 tons.T ransverse ai r ducts, spaced at 25 f t . i nterval s , dis -tr i bute venti l at i on ai r suppl i ed by l o w pressure fans.

Beets are reclaimed at up to 150 tons per hour by f ront-end l oaders working the toe of a pi l e. They l oad a move-abl e hopper posi ti oned above the reclaim bel t conveyor.The reclaim conveyor di scharges i nto the w e t dump hopperfrom which beets enter the f lume system.

B e e t Washing -- The beets are cl eaned to remove rocks,trash and soil pr io r to s l i c ing . Beets are slui ced i ntothe f lume system wi th a mixture of f resh and recycl edflume water. A f eeder which i n the f lume regul ates thef low of beets i nt o the downstream por ti on of the flume.A Dyer-type rock catcher removes rocks from the l i ghterbeets using an upward f l ow of water to l i f t t he beetsand allow the rocks to settle downward i n the rock chute.A chai n conveyor removes the collected rocks. Weeds,l eaves and beet t a i l s are removed i n a Dalton-type trashseparator . The tr ash i s di scharged from a rotati ng drum

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onto a bel t conveyor f or trash di sposal . The beets returnto the f l u m e and enter the washer which has a dewateri ngsection at the i nl et. Fresh water i s added as the beetspass onto a curved screen and are washed by sprays andby agi tati on. Cl ean beets are di scharged by a dewateri ngscrew onto a bel t conveyor. Flume water and wash waterpass over a trash screen and i nto a sump. The water canbe recycled di rect l y or di scharged to a grav i ty c l a r i f i erf or cleanup. S i l t settl es o u t i n the c l ar i f i e r and i spumped to one of t w o s i l t ponds. The c l ar i f i er overfl ow(about 80 percent) i s recycled to the head end of the flume.The s i l t ponds allow fu r ther c l ar i f i cat ion to occur soaddi ti onal water can be recycl ed. Sl udge accumulates i nthe ponds and i s dredged at the end of the beet processingseason.

Beet S l i c i ng -- Washed beets are conveyed to a bucketel evator which l i f t s them to a hori zontal t ransf er con-veyor above the 50 ton capaci ty cl ean beet bin.i s mounted above three 1000 ton per day capaci ty rotary

The bi n

slicers. Rotating kni f e blocks c u t the beets i nto thi nslices (cossettes). The kni f e blocks are changed o u tabout every four hours f or sharpening. Compressed ai ri s used to cl ean the blocks duri ng operation. The cossettesare fed onto a weigh bel t conveyor (weightometer) whichautomati cal l y weighs and totals the dai l y sl ice.

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Diffusion -- Hot water extraction of the j ui ce from thecossettes i s carr i ed out i n a continuous slope di f fuser .The 3200 ton per day capacity Si l ver D.d.S. di f f user i ssteam j acketed to mai ntai n the j ui ce and pul p at thedesi red temperature ( 160 F average). Cossettes enter thelower end and are conveyed upward by the scrolls. Hot waterand pul p return water enter the top end and pass downwardcountercur rentl y contacting the cossettes. By di f fus ionthe j ui ce phase passes from cel l ul ar material i n t o thel i qui d. Exhausted cossettes (pulp) are di scharged fromthe top end of the di f f user and drop onto a dewateri ngscreen. The thi n j ui ce i s dischargd (on l evel contr ol )from the l o w end of the di f f user i nto a tank. The th i nj ui ce amounts to about 120 percent based, i n the weight ofthe entering cossettes. The sugar content i s 13.65 percentand represents a 97.8 percent sugar recovery.

Pulp Dewatering -- The raw pulp i s screened to remove freew a t e r and then conveyed to eight vert ica l s c r e w pressesf or dewateri ng to about 80 percent moi sture content.Nearly 33 tons per hour of pressed pul p are generated.Th i s material i s conveyed to by-product dryi ng. Screeningwater and press water are pumped through a heat exchangerand returned hot (158F) to the d i f f usi on water i n l e t .Heated makeup water i s also added to the return waterstream ahead of the heat exchanger. Steam preheati ng thewater hel ps to control bacteri al growth i n the di f f user.

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Thi n J ui ce Concent r at i on -- Mul t i pl e- ef f ec t evapor at i oni s used t o r ai se the sugar concent r at i on i n t he j ui ce f oropt i mum f er ment at i on and al cohol r ecover y. A modi f i edt wo- ef f ec t evapor at or sys t em r ai ses t he sugar concent r at i ont o 19. 8 per cent wei ght . Hot geot her mal br i ne ( 280 F) i n t hef i r s t ef f ec t vapor i zes wat er whi ch i s used as s t eam t o t hesecond ef f ect . The evapor at or c ondensat es al ong wi t h vaporf r om t he second ef f ec t pr eheat t he t hi n j ui ce f eed. The r e-mai ni ng vapor f r om t he second ef f ec t pr ovi des a l l o f t hedi f f us er ' s s t eam needs . The coi ncent r at ed j ui ce i s t hencool ed t o 80F pr i or t o f er ment at i on.

Fer ment at i on -- Fer ment at i on of t he sucr ose sol ut i on i scar r i ed out bat ch- wi se i n t en 170, 000 gal f er ment er s t oy i el d a net 2540 gal l ons per hour of et hanol . Tabl e 3-3summar i zes t he f er ment at i on par amet er s. The t ot al cycl et i me per f er ment er i s 6 0 hour s and ei ght bat ches ar eal ways i n some st age of f er ment at i on at any one t i me.One f er ment er i s bei ng f i l l ed and one i s bei ng empt i ed andcl eaned at any one t i me.

At t he s t ar t of a cyc l e, concent r at ed j ui ce, yeas t andnut r i ent s ar e pumped i nt o t he f er ment at i on t ank. H C 1 i sadded i n- l i ne to dr op t he pH t o 4.5 f r o m 6. 5. As t hef er ment at i on pr oceeds, heat r el eased by t he r eact i oni ncr eases t he mash t emper at ur e. Car bon di oxi de f or med i nt he r eac t i on al s o i s r el eased i nt o t he vapor space.

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Tabl e 3- 3PRI NCI PAL DESI GN BASES - FERMENTATI ON

SUGAR BEETS

Chem cal React i ons and Conver s i ons ( Basi s 100 l b gl ucose)Sucr ose hydr ol ys i s ( 100%)

C12H22011 + H2 - - - - - - - - - - - )C6H120695. 0 l b + 5. 0 l b 100. 0 l b

Gl ucose conver s i ont o et hanol ( 91. 88%)

yeas t 2C2H50H + 2C02gH12691. 82 l b 46. 97 l b 44. 85 l b

t o yeast . ( 3. 636%)C2H1206 i nnocul um yeas t + 1 452C02 + 1. 452 H203. 6363 l b 1. 8181 l b . 9091 l b . 9091 l b

t o o t her o r gani c s ( 4 . 545%)2. 5 CgH1206 - - - - - - +3CH3CHO + 4C02 + CH3( CH2) 3CH2 OH + 3H2O

4. 5454 1b. 1. 3333 l b 1. 777 l b . 8897 l b . 545 l b

Fer ment at i on --Yeast MakeupNut r i ent Requi r ement sFer ment at i on Ti meFer ment at i on Temper at ur e

0. 2385 l b/ 100 l b et hanol pr oduced0. 954 l b/ 100 l b et hanol pr oduced48 hour s85O F - goo F

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Table 3-3 (conti nued)

PRINCIPAL D ES IGN BASES - FERMENTATION

22 kcal/g-mole (430 Btu/l b ethanol )Fermenter F i l l TimeFermenter Empty & Clean TimeT otal Batch Cycle TimeMaximum/Design Capacity

Off-gas Scrubbing --Vapor super f i c i al veloc i tyL/GPressure dropG as i nl et temperatureG as ex i t temperatureLiquid c i rculat ion temp.Makeup water

Beer WellSurge capaci tyRecirculation rate

6 hours6 hours60 hours120 8

3 feet per second20 ga1/1000 ACFM2. i n. W.G.g o o F (avg)60 F (avg)60 F (avg)repl acement of water i n off-gas

8 hr s @ 80% f u l l1500 gpm

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The mash i s ci rcu l ated through pl ate- type exchangers whenthe bulk temperature reaches about 90' F.( 60 F ) removes the bul k of the heat of reacti on and l i m i t sthe mash temperature rise. Cooling i s required only partof the fermentation t i m e so one exchanger can be used toserve tw o fermenters. A l ternatel y, the mash i s circulatedcontinuously, most of the t i m e bypassing the exchanger.Evolved vapors, mainly C 0 2 , are water- scrubbed i n a traycolumn to recover ethanol . Blowdown from the scrubber i spumped to the beer w e l l . Scrubber off-gas i s vented tothe atmosphere.

Cooling water

A t the end of the 48 hour f ermentati on period, the fermentedmash contai ni ng 9.8% ethanol i s pumped to the beer w e l l .The empty f ermenter i s chemi cal l y cl eaned by i nternalspraying machines, st er i l i z ed wi th an i odine sol uti on andrinsed with sterile water. The spent sol uti ons ar e routedto wastewater treatment, and th i s tank i s agai n ready forservi ce.

The fermented mash (beer ) charged to the beer w e l l containswater, yeast, dissolved sol i ds ( organic and inor gani c) ,fusel o i l and aldehydes i n addi ti on to the ethanol . The netyi el d of ethanol based on sucrose i s 91.6 percent. An eight-hour surge capaci ty i s provi ded and the tank contents areci rcul ated continuously to provide a uniform feed to thed i s t i l l at i on sec tion.

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Ethanol Di st i l l at i on -- Fermented beer from the beer w e l li s preheated wi th the condensing vapors from the azeotropi ccolumn and the beer s t i l l through feed/tops exchangers torecover the condensing load of the vapor f rom both columns.The beer i s f ur ther heated through a feed/bottoms exchangertaki ng addi ti onal heat from the bottom of the beer s t i l l .A t r i m heater using geothermal f l ui d w i l l provide .the f i nalheat necessary to provide a bubble-point feed i nto thebeer s t i l l .

The beer sti l l i s operated at a pressure of 1 0 psig at thebottom of the column, which corresponds t o the maximumtemperature avai l abl e from the geothermal f l ui d f or r eboi lduty i n the thermosiphon reboi l er. Fusel oi l i s concentratedi n the upper par t of the column and i s removed and water-washed i n a separate fusel oi l washer. The alcohol and waterrecovered from the f usel o i l washer i s returned to the beers t i l l feed. Trace quant i ti es of aldehyde produced i n thefermenter i s removed as an overhead stream. A f t e r conden-sati on, the aldehyde i s rebl ended wi th the ethanol product.Ethanol-water close to the azeotropic composition i s con-densed agai nst the in-coming beer f eed pr i or to i ts entryas a bubble-point feed to the azeotropi c di sti l l ati on column.

Benzene i s used to form a ternary azeotrope with the ethanol/water mixture i n the azeotropi c column. The water i s removedoverhead wi th the benzene. The condensed l i qu i d i s collected

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i n a phase separator. The benzene i n the upper phase i srecycl ed back to the top of the column. The aqueous phasecontai ning trace quanti ty of hydrocarbon i s fed to a hydro-carbon st r i pper . The bottom stream of the azeotropi c columni s 99.2% ethanol . Th i s stream i s cool ed and pumped t o storage.

I n the hydrocarbon stri pper essenti al l y al l of the hydro-carbon remaining i n the feed i s removed overhead and fedback to the f eed stream t o the azeotr opi c column. The bottomstream i s sent to wastewater treatment.

By-product Recovery -- The bottom stream from the beer s t i l lcontai ning the yeast and dissol ved sol i ds i s pumped to thewhole sti l l age tank f or f urther processi ng.

The whole s ti l l age a t thi s poi nt combines with t he beetpul p and i s centrifuged to produce a thi n st i l l age and a35% sol i ds stream f or dryi ng to produce an animal feedby-product.

The t h i n s t i l l a g e i s concentrated to 54% medium syrup througha mechanical vapor recompression f al l i ng f i l m evaporatorsystem. The condensate collected from th i s mechanical vaporrecompression system i s f ed to the wastewater treatmentsystem.

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The medium syrup combines wi th the centri f uged so l i ds al ongwith some recycled dri ed sol i ds and f ed to a turbul i zer tomix these streams to y i e l d a 45% s o l i d stream as a feed tothe geothermal f l u i d dryers. The f i nal product from thedryers i s 90% so l i d and 1 0 % moi sture. The dr i ed product,part of which i s recycled, i s f ed through a hammer m i l lf or si z e reducti on fol l owed by cool i ng prior to i ts con-veyance to the by-product storage awai ti ng shipment.

The material balance f or th i s secti on of the pl ant i s notcomplete at t h i s t i m e .

3 . 4 Potato Processing DescriptionPotatoes are processed for f i ve continuous months each year,March through J ul y , f ol l owi ng the f our months of sugar beetprocessi ng. 360,000 tons of potatoes are received by thepl ant f or cl eaning and processi ng during t hi s peri od. On-site storage capacity i s 36,500 tons. The desi gn mash ratei s 2,630 tons of potatoes per day. T he d a i l y mash conta ins389 tons of star ch which i s converted to 432 tons of sugar.A t the end of batch f ermentati on, t h i s sugar i s convertedto 203 tons per day of ethanol . The beer (11.25% w t . ethanol )i s d i s t i l l e d to a 87%w t . overhead product, then dehydratedto a 99.2% w t . ethanol product i n a benzene-water-ethanolcolumn.

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The whole st i l lage from the beer s t i l l i s centrifuged.The cake i s dr ied t o 90% sol i ds. A pproximately 206 tonsof th i s dri ed animal feed are produced per stream days.F u s e l oi l s (higher molecular weight alcohols) are alsorecovered as a by-product.

Design BasesTable 3 . 4 presents the assumed composi tion of the potatoes proces-sed i n the pl ant.

Table 3-4AVERAGE POTATO COMPOSITION ( C L E A N )

FJ aterStarchP rotei ns and f atsFiber

77.5%15.0%

2.1%5 .4%

100.0%

A l l foreign matter i s removed and 0 . 1 percen, of the sdry matter i s assumed to be lost i n dewateri ng.

l u b l e

Potatoes are processed 24-hrs per day, seven days per week ata design stream factor of 90 percent (2630 tons per stream day).Tables 3 . 5 and 3 . 6 summarize the pr i nc i pal desi gn bases f or eachprocess secti on.

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Table 3-5P R I N C I P A L D E S I G N BASES - PROCESSING

POTATOES

Potato Receiving and StorageReceiving peri odsCarrierLoads per dayDirect process

Potato WashinaF1ume w aterWash waterDirect recyclePond recycl eL ost to sludge

Potato MashingMashing rate

Mash DewateringRaw mash moistureDewatered mash moistureConcentrate moisture

dayl i ght hours, 7-days per week20-ton net tr acto r - tr ai l ers(end dump)1302607 tpd

1920 gal/ton of potatoes

100 gal/ton of potatoes (desi gn)fl umed (desi gn)

98 percent (desi gn)

870 tpd per machine

78%w t69%w t98%w t

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Table 3-6PRINCIPAL D E S I G N BA S ES - POTATO FERMENTATION

Chemical Reactions and Conversions (Basis 100 l b. gl ucose)

Glucose conversionto ethanol (91.818%)gH1Z06 yeast 2 C2H50H + 2 C O291.812 l b 46.97 l b 44.85 l b

to yeast (3.636%)C6H1206 innoculation yeast + 1. 452 C 02 + 1. 452 H 2 03.636 l b 1.8181 l b . go91 l b .go91 l b.

to other organics (4.545%)2.5 CgH1206 yeast 3CH3CH0 + 4 C 02 + CH3 (CH2)34.545 l b 1.3333 l b 1.777 l b .8897

CH20Hl b

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Each Process sect i on i s descri bed below. F i gure 3-4 i s anov eral l block diagram of the potato processing 'and F i gure 3-5i s a process flow diagram of the steps up to d i s t i l l a t i o n .Figure 3 . 6 shows the products recovery.

Potato Receiving and Storage -- Potatoes are shipped t o theethanol f ac i l i ty by end dump tr actor- tr ai l ers. The n e tl oad averages 20 tons. T rucks are weighed i n (gross) ando u t (tare) to record the as received tonnages. A t thescale, trucks ae di verted t o the dump stat i on where potatoesare dumped i nto the po tato cellar which prov i des storagespace f or 1 4 days' potato requi rement (36,500 tons).Potatoes are recl aimed by front-end loaders working at thetoe of a pi l e. The l oaders tr ansf er the'potatoes to thereclaim bel t conveyor which di scharges i nto the sl ab stor agearea which provi des potato storage f or 8 hours of pl antoperation.

Potato Washing -- The potatoes are conveyed v i a a flume toone of three potato washers. F lume water is recycl ed.Wash water i s supplied to each washer at 75 gal l ons perminute. The wash water f l ow f rom the washer to a two-compartment set t l i ng pond. Suspended so l i ds settle o u ti n the f i r s t compartment and cl ari f i ed water f l ows i ntothe second compartment from which i t i s recycl ed as f lumewater makeup. Sludge accumulates i n the sett l i ng pondand i s dredged a t the end of the po tato processi ng season.

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Le

1

III

I


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.

STEAM .-r A k X

_- I r - - - - - - -i I - II8.

3 ENX4TE 5 OOKED POATOMAS1;IO0 OI lQt o I 'V 3I 790-1921bI I r -3987

L l----L 0- . '0:3L

t7373. t

po*o100 1 33 I IO0DO kC, 553 1 0 0 - 0 167 1bc100.0 100-0.


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Potato Mashing and Dewateri ng -- Washed potatoes are con-veyed to one of three feed bins and then to three di si nte-grators where the potatoes are crushed, and resi dual f orei gnmatter (tramp i ron, etc.) i s separated from the mash anddi scharged to waste. The mash f lows from the di si ntegratorsto screens where course potato pieces are removed and re-cycled to the di si ntegr ator s. The screened mash f l ows to acentri f uge where i ts moi sture content i s reduced to approxi-mately 69 percent. The cent rate containi ng 0.3 percent starch,i s discharged to the wastewater treatment f aci l i ty .

Starch L i quefaction -- A t w o percent sol uti on of sodiumhydroxide i s added i n- l i ne to raise the pH of the dewateredmash from 5.6 to 6.5. A lpha amylase i s next added to themash to break down the star ch bonds and 10,670 pounds perhour of 10 psig direct steam are added to raise the tempera-ture of the mash to 221 F f or gelati ni zati on and cookingof the starch. The star ch i s cooked f or f i ve minutes i n atubular cooker a t 221 F and i s then f l ash cooled to 203O F.The cooked mash next enter s a baf f l ed hold tank which pro-vides 90 mi nutes detenti on t i m e . A gitators are providedf o r adequate mixing of the hold tank contents to preventset tl i ng of suspended matter. The hol d tank ef f l uent i scooled to 140 F and treated wi th a f i ve percent hydro-chlor i c ac id so luti on to lower the pH from 6.5 to 4.5.

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Sac char i f i c at i on -- Gl ucoamyl ase i s added t o t he l i qui f i edst ar ch t o br eak down t he st ar ch dext r i ns to pr oduce a hi ghy i el d of f er ment abl e gl ucose . Thi s t akes pl ace i n t en 170, 000gal l on sacchar i f i cat i on vessel s each wi t h 60 hour s r et ent i ont i me.mai nt ai ns t he cont ent s at 140 F. Each vess el i s al s oequi pped wi t h an agi t at or t o ensur e adequat e m xi ng oft he r eact ant s.

A s t eam j acket ar ound each sacchar i f i cat i on vesse l

Fer ment at i on -- Fer ment at i on of t he gl ucose sol ut i on i scar r i ed out bat ch- wi se i n t en 170, 000 gal l on f er ment er st o yi el d a net 2540 gal l ons per hour of et hanol .i n t he beet pr ocess i ng sect i on summar i zes t he f er ment at i onpar amet er s . The f er ment at i on condi t i ons ' ar e i dent i cal t o

Tabl e 3-3

t hat descr i bed i n t he beet sect i on.

Al cohol Di s t i l l at i on -- The di s t i l l at i on s cheme f or t hepot at o case i s i dent i cal t o t hat desc r i bed f or t he beetcase except f or a hi gher sol i ds concent r at i on bot t oms t r eam f r om t he beer s t i l l i n t he pot at o case. The f i ber sf r om t he pot at o pr ocess i ng wer e not separ at ed pr i or t odi s t i l l at i on, t her ef or e al l of t he f i ber s c ome i n wi t ht he beer f eed t o t he s t i l l .

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By-product Recovery -- The whole st i l l age f or the potatocase has a much lower dissolved sol ids content than i n thebeet case. T herefore, the thi n st i l l age produced from thecentr i f uge may go di rect l y to wastewater treatment withoutbeing processed through the mechanical vapor recompressionsystem. The energy consumption, ther ef or e, i s expectedto be lower than that necessary f or the sugar beet case.

The centri f uged so l i ds from the whole s t i l l a g e w i l l berecovered i n a simi l ar manner to that descri bed underthe sugar beet case.

3 . 5 Wheat Processi nsWork on the wheat processing opti on has been started.Equipment manuf acturers have been contacted and a wheatprocessi ng pl ant ( f l our m i l l ) was vi si ted. Wheat mi l l i ngtests are being conducted to determine whether removalof the gluten por ti on of the wheat i n the mi l l i ng sectionof the pl ant w i l l have a f avorable ef f ect on processeconomics. The process flow diagram w i l l be producedaf te r t h e test results become avai l abl e.

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Sec t i on 4GEOTHERMAL RESOURCE

The over al l pr ocess heat r equi r ement s wi l l di c t at e t he geot her malbr i ne requi r ement s. These have not been compl et ed, but a pr el i m -nary est i mat e of t he r equi r ement s i s bet ween 100 and 200 m l l i onBTU/ hr . The f ol l owi ng di scussi on cover s how t he geot her mal br i newi l l be used i n t he syst em and t he br i ne f l ow r equi r ement s.

4.1 Resour ce Ext r act i on and Requi r ementThr ee di f f er ent ener gy ext r act i on syst ems wer e consi der ed:( 1) f l ashed s t eam ( 2 ) pr essur i zed geot her mal f l ui d wi t ha di r ec t t r ans f er of heat , and ( 3 ) use of a s econdar y heatt r ans f er f l ui d. The pr es s ur i zed f l ui d s ys t em has beens el ec t ed s i nce i t m ni m zes t he pot ent i al s cal i ng pr obl emsi n t he br i ne t r ans f er s ys t em Thus , t her e wi l l be no di r ec ti nj ec t i on o f t he br i ne i nt o t he pr ocess s t r eams . I n t heevent s t eam i nj ec t i on i s r equi r ed, as i n pot at o cook i ng,a secondar y loop i ncor por at i ng a s t eam gener at i on sys t emwi l l be ut i l i z ed.

Si nce t he over al l heat bal ance i s not compl et ed, onl y apr el i m nary est i mat e can be made f or t he geot her mal f l ui df l ow r equi r ement s. F i gur e 4- 1 shows t he r el at i onshi pbet ween geot her mal f l ui d r et ur n f l ow t emper at ur e and t hi snumber of wel l s r equi r ed and t he r e l at i ve ener gy costt o suppl y t he pr ocess heat l oad.

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.

I-v)84w>Fra

1 .o

0. 75

0.50

0.25

TOTAL HEAT LOAD =100x l o6 BTU/HRTBRINE IN =2800~WELLS, PUMPING POWER,AND LAND ONLY

INTER ESTRATE

0 I I 1 J150 175 200 225 250BRINE OUT- F

12108 NO.

OFSUPPLY4 WELLS

20

Figure 4-1 R E L A T I V E E N E R G Y C OS T VS B R I N ER E T U R N T E M PE R A T U RE


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4 . 2 Geothermal F l ui d P roperti esPhysi cal and chemical proper ti es of the geothermal f l ui dconstrai nt the method by which the f l ui d may be used.The ef f ects of these properti es relate to the scal i ngtendency of the f l ui d, and potent i al cor rosi on by thenon-condensible gases and br i ne sal i ni ty .

A nal ysi s of the total dissolved sol i ds i n the Raf t RiverKGRA i ndi cates t w o di f ferent sources of geothermal waterexi st i n deep wells. One of these i s of a l o w sa l i n i t y(approxi matel y 1000 ppm TDS) and one of a high sal i n i ty(about 6000 ppm TDS). These waters are associ ated withl ocal geographical condi ti ons known as the Bri dge f aul tand the narrows Structure (Ref. 3 ) .

The f l ui d temperature of these t w o sources i s also d i f -ferent. Bottom hol e temperatures i n deep w e l l s vary byas much as 5 F f or the same depth.

Non-condensible gases are present i n the geothermal bri ne.M aterials test i ng has shown there are trace amounts ofhydrogen sul f i de i n the bri nes (Ref. 4 ) . These are ofsuf f i c i ent quanti ty to cause corrosi on problems wi thcopper al l oys. The f i nal materials sel ecti on w i l l takethe f l ui d properti es i nto consi deration.

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Section 5CONCEPTUAL D E S I G N OF GEOTHERMALENERGY G ATH E R I N G , TRANSFER,A ND DISPOSAL SYSTEM

A v i s i t w as made to the DOE Raft River s i te on September 19 and20 to obtai n design i nformati on on the geothermal resources andcost estimates f or use of the geothermal resources at the Crookand Gl over propert i es. A summary of the geothermal resourcecharacteristics i s shown i n Table 5-1.

5.1 Well F i eld DesignDiscussions were hel d wi th geol ogi st, hydrol ogi sts, andengineers of EG&G concerning the Raft River area. N o reporti s avai l abl e which can supply the design condi ti ons f orthe geothermal resources nor i s there any general agreementon the extent of the resource.

There i s major fau l t i ng in the R a f t R i v e r area so that i ti s very di f f i cu l t to predi ct the results from expl orati ondr i l l i ng even i f it i s near an exi sti ng w e l l . M ulti -l eggedwells are not worth the addi ti onal expenditure j u s t to i n-crease the flow but can be used to improve a bad w e l l .The fl ow i ncrease i s small f or multi -l egged wells, the costi s l arge, and there are chances of plugging one or theother l egs due to obstructions from tai l i ngs.

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Table 5-1G eothermal ResourceDesign Bases

W e l l SupplyTemperature = 280 F ( at surface)Flow = 600 gpm/well wi th 200 KW pumping powerDepth = 5000 f eetCost = $700,000 to $900,000 (1979$)(not i ncl udi ng exploration cost)L i f e = One new w e l l every other year f or 7 w e l l s d r i l l e d .Well Spacing - On a 1/ 4 M i l e Square G r i dNon-condensible Gases - N o H 2 SRedundancy - 7 wells dr i l l e d f o r 5 producing w e l l s( the 2 wells cannot be used , f or re-in ject ion) .Scal ing - Flashinq of the bri ne should not be allowed.Keep pressure above 100 psig.

Br ine D i s D o s a lSame quanti ty as obtained from the suppl y w e l l mustbe rei ni ected.One rei nj ecti on w e l l per 2 supply w e l l s i n to 1500 to2500 aqui f er.Maximum rei nj ect i on pressure = 250 psigN o particles greater than 200 micron

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Estimates of w e l l operating conditions also vary.the 5 MW Power Pl ant w as designed f or 290 F, more recentdata i ndi cated an average temperature of 270 to 280 F(pumped and at the wel l head). A ddi ti onal temperature l os si n the pi pel i nes can be expected. Flows of 500 to 600 gpmper w e l l are possi bl e wi th pumping. Well depths are typi-c a l l y 5000 feet.

A lthough

A lthough w e l l s can be sel f f l owing, pumping i s recommended.A study f or w e l l pumping f or the 5 MW pl ant concluded therei s an optimum operati ng pressure. I ncreasing the pump headi ncreases the fl ow. Submersible pumps have been consi dered.Their use should be consi dered as developmental f o r th i sapplication. Line pumps can be used f o r pump depths of800 f eet and possi bl e to 1200 to 1500 feet.

W e l l l i f e i s unknown. A l though some wel ls have been i nexi stence si nce 1975, i nsuf f i c i ent i nformation i s avai l -able to project the operating l i f e. Most analyses arebased upon a maximum l i f e of 5 years. L onger w e l l f l owsare possibl e but at the expenses of i ncreased pump sett ingdepths and pump horsepower. T herefore, a recommendationof one new w e l l every other year f or every 5 to 7 pro-duction wells was made.

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5.2 Bri ne Gatheri ng SystemA supply w e l l f i e ld l ayout using a square grid with aw e l l spaci ng of 1/ 4 t o 1/ 2 a m i l e i s recommended. T h i s i ssimilar to o i l f ie lds . A general comment i s that there i si nsu f f i ci ent space on the Crook and Gl over property t osuppl y the ethanol production f ac i l i ty (based upon o urpreliminary estimate of f ive wells). A djacent pro perti esw i l l be needed to supply the heat load requi rement.

5.3 Brine DisposalF o r br ine rei nject ion, the f l u i d must be inj ected suchthat it does not contaminate the drinking water supply.Normally t h i s might be i nt o the same aqui f er the bri ne i sobtained from ( at l east about the same depth). More recenttesti ng has shown an aqui f er at 1500 to 2500 f eet w i l l acceptreinjected fl ow readi l y (Ref. 5). Whether th i s can be usedon a long term basi s i sn ' t known. I t i s esti mated a r e i n -j ecti on pressure of 250 to 300 psi i s requi red at the endof f i ve years. I t i s recommended ther e be one standbyw e l l f or every t w o in ject ion wells. One re inject ion w e l lper t w o supply w e l l s i s required for the shallow aquiferwhereas a one-to-one ratio i s requi red f or the deeperaquifer.The only present pretreatment f or rei nj ecti on i s 200 micronf i l t r a t i o n . 5 micron f i l tr at i on may be requi red.

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Section 6ECONOMIC FACTORS

During the v i si t to R a f t River, discussions were held with DOEpersonnel i n order to obtai n w e l l d r i l l i n g costs. I n addition,discussions were held wi th the owner of the t w o properties underconsideration - Gary Crook and Frank Glover.6.1 Geothermal Well Costs

W e l l d r i l l i n g costs were obtained from the DOE i n a paper"Geothermal W e l l D r i l l i n g Estimates Based on Past W e l lCosts". I t i s estimated that an annual i nf l ati on rate f orw e l l s i s as high as 25%. A 5000 foot w e l l may cost up to$900,000 (1979$) not including exploration costs. A reviewof other DOE contracts showed expl orati on costs to rangefrom $11,000 (one case) to $100,000 ( t w o cases) (Ref. 6) .

6.2 Crook's PropertyM r . Crook provided thr ee al ternati ves f or the cost of h i sproperty. 1) An outr i ght sale would cost $350,000 (landval ue of hi s property by other estimates.is about $10,000) .2 ) A lease arrangement at $25,00O/year wi th him retai ni ngthe r ight to use of 150 gpm of geothermal water at lessthan 180 F for h i s greenhouse. 3 ) S e l l seven acres noti ncl udi ng greenhouse but i ncl uding geothermal r i gh ts at$150,000. For th i s case he w i l l also retai n the r i ghts

I

to the use of 150 gpm f l ui d fl ow.6- 1


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M r . Crook does no t have water r ights. H i s land i s l ocatedon a f l ood pl ai n and would probably be a poor location foran ethanol pl ant.

6 . 3 Glover's ProspectFrank Gl over owns 160 acres at the Raft River site.H e has hi red an apprai ser to determine the val ue of hi sproperty but has not yet obtai ned the report. When hedoes, he w i l l send the results.

There are no producing water wells on hi s property. H ehas peti ti oned to d r i l l a small exploratory w e l l but asyet has not recei ved approval .

6. 4 Electric R a t e sE l e c t r i c i t y i s obtained from the Raf t Ri ver Elctrical Co-op. A rate schedule was obtai ned and shows the powercost for industr ia l user to be less than 0.02 $/KW-Hr.The co-op indicated t h e rates w i l l rise substant ial lyi n December. For insta l lat ion cost of commercial si z eelectrical loads, speci al rates may be obtai ned.

6.5 Cooling WaterThe Raft River i s a closed resource so that there can beno consumptive uses of water. T h i s i s i nterpreted tomean both geothermal and cool i ng water. Present waterusers may se l l their water r ights to other part i es i n

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the f uture. I n additi on, water r ights are given onlyon rea l i t i ve ly l a rge areas of l and. Thus the 10 acresof the Crook's property does not have water r ights.However the 1 60 acres that h i s 1 0 acres i s part of ,has water r ights.

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1.

2 .

3.

4 .

5.

6.

REFERENCES

Gr ai n Mot or Fuel Al cohol - Techni cal and Econom c Ass essmentSt udy, HCP/ J 6639- 01, Raphael Kat zen Ass oci at es f or U. S. DOEunder Cont r act No. EJ - 78- C- 01- 6639.

1978 Agr i c ul t ur al St at i s t i c s, USDA, Ec onom c , St at i s t i c sand Cooper at i ve Ser vi ce, Boi se, I daho, 1978.

C. A. Al l en, R. E. Chaney, and R. E. McAt ee, Geochem cal Model -i nq at Raf t Ri ver , Geot her mal Resour ces Counc i l , Tr ansact i ons,Vol . 3, Sept . 1972.

R. L. Mi l l er , Cor r osi on of Copper - Base Al l oys i n a Geot her malBr i ne, AI ME I nt er nat i onal Symposi um on Oi l f i el d and Geo-t her mal chem st r y , J an. 1979.

Di scuss i ons wi t h R. Chappel of DOE, I da ho Ope r a t i o ns Of f i ceand K. J ones of EG&G, I daho, Sept . 1979.

Di scuss i ons wi t h C. Al l en, D. Gol dman, and S. Spencerof EG&G, I daho, Sept . 1979.

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