Chi ㈣JChvm ．Eng，i i ( 1j 1—8( 2003)St udyonO pti m al Strategyof G rade Transi ti oni n Industri alFl ui di zed Bed G as．Phase Pol yet hyl eneProduct i on ProcessW AN GJ i ngdai ( t靖岱) andYAN GYongrong( 阳水荣) +D epartm ent of ohem |calEngi neerl ng，Zhej i angU nl versi ％y，H angzhou 310027，Chi na了&{万禽AbstractD roduct i on D rocessby theopti m i zati onof operat i ag vari abl es，such晒pol ym eri zatl on t铀pera札re，the rati o ofhydrogeato ethyl ene，the rari o of co- m onom erreel ％fl ow ( M FR) ．ui nduded i n"obeobj ecti vef unctl oq，[ or rcstral ni ngthesharp edl ustm cntand narrow i ngthe di stri buti on of m ol ecul ar w ei ghtof the resi nbed l evel 时e decreased i n orderThi s。D tl m l zati onprobl emi s sol ved by an al gori thmof sequenti al quadrati c program m i ng( SQ P) i n M ATLABThere bconsi derabl e di f i ef ence betw een the forw ard transi ti on and reversetransi ti onofgradew i t h regardto theoD erat i ngvari abl es due to thenon- l i neari ty of thesystem ．The gradetransi ti on m odelti Ineyi el d( STY) process w i t h the so- cal l ed condensed m odelm ul ti ．producttheopti m al gradetransi ti on roodel ．A曲quenti al transi ti onof si x com m erel alanopti m al m ul ti - product operati on．Keyw ordspol ym er，conti nuous pol ym eri zati on，gradetransi ti on，m ul ti —product operati on，tw o- l evel opti m i zati onA m odelof grade transi ti on hpresent edThequant i t y of off-speci fi cati on productfor a com m erci al i zed fl ui di zed bed gab- phase poLyet hyLeneandthe ti m e of gradetransi ti on can be m i ni m l 20dto ethyf exxe，f eed rate of catal yst，andbed l evelAnewperf orm ance i ndext the rati oolof operat i onvari abl esi s recon2rnended thatItcatal ystf eedrate andto reduce the gradetransi ti on ti m e and the quant i t y of off-speci fi cati on producti s ext endedto ahi gh spaceoperat i on．I n theend，al l opti m i zati on strategyfortransi ti on i s propodedw i t h tw o- l evelopti m i zati onof the obj ecti ve f unct i onJ ( z，u) onthe basi s ofpol yet hyl enegradesi s l l l ustrated for1 I N TRoD U CTI oNToday pl asti c pol ym ersO U S ki nds ofproducts．sucha8partsfor cars、dl i ferentki nds ofbottl es，fi l m s and fram esances．Each usage requi res di fi erent pol ym ers w i thsom edesi gnated speci fi cati ons．Inorder to m eet thesedem ands，pol ym et com pani es often have toproducevari ousgradesof apol ym er．Therefore m any typesofpol yethyl eneshoul d beproducedi n asystemw i thor severalreactors．Thi s i nvol vescess operati onthat i s cal l edgrade transi ti on．The fre-quencyandm agni tudeofgradetransi ti ons D．reusual l ydeterm i nedbyboth thepri ceand m arket dem ands forpol ym ers，G rude transi ti on l eadsoff-specti fi cati on pol ym ers to beproducedsi ncegradechangeover w oul d be m ade som eti m eseverya fewdaysand the transi ti on ti m eof pol ym etphase pol yethyl ene reactor i s general l y from10 to 30hours．Iti svery i m portantcom panytoperformagood gradetransi ti onopera-ti on ai m ed atproduci ng l ess off-specti fi cati on po妒m etand／or reduci ngof the ti m e of grade transi ti onsi nce the m arketspecti fl cati on pol ym ers D i e qui tedi 船rentl l |．Si ncl ai rhas outl i ned som epracti cm aspectsthegrade transi ti on probl em l Ⅲ．Ray m adedynam i csi reul ati ous offor t w o fl ui di zed．bed reactors，and theydeterm i nedthatthecatal ystfeedrate，hydrogenfeedrate，andbl eed fl ow rate are i m portantarew i del yused asvari -f or el ectri c appl i -ouea speci alpro-t o a97reatdesl ofi 12 an i ndustri algasforapol ym er-produci ngpri cesofon-specti ti cati on and off-ofRam anathan andgradetransi ti onvari abl es foraccom ，pl i shi ng rapi dstone for opti m alsol vi ngl em ．M cAul eyandM acG regorfi rst obtai nedopti m algradetransi ti on strategi esl ene reactort5J ．0hshi m atransi ti ons LSJ．gradetransi ti on strategy[ 4J．a dynam i c m odel - basedAndi t w asam i l e—Byopti m i zati on prob—i nal so conductedal oop and gas· phaseagas phase pol yethy—opti m algrade-transi ti on strategi espol ypropyl enereactorby usi ng dynam i c progranl m i ngaftersi l npl i fyi ngthe correl ati on m odel s ofpol ypropy-l ene resi nspeci fi cati on ofAl thoughcorrel ati on m odel s w i th the vari ati on of m el ti ndex(M I)，densi ty, tem peraturesandgasCO ncentra-ti ons i n the reactor m ake opti m i zati on to be sol vedeasi l y, M cAul ey andM acG regorD] 、O hshi m a[ 6J di dnotful l y characteri ze other speci ti cati ons ofsuch as m ol ecul arw ei ght di stri buti on( M W D) De．bri nge￡alsi m ul ated grade-transi ti on operati ons forvari ous ki nds of pol ym eri zati on process by usi ng thedynam i csi m ul ati onpackage“ PO LYRED ” 川TakedaandRay al so si m ul ated the opti m al grade-transi ti onstrategi estots w i th bi m odal products by usi ng“ PO LYRED ” ( slH ow ever，them ethods adopted i nRefs．『7, 81to obtsi ntheopti m alInthi s study, several i m provem ents ou the basi sofM cAul eyandM acGregor’ s grade transi ti on m odel [5】are m ade to obtai n theopti m um profi l es for gradetransi ti oneffecti vel y．Fi rst( M FR) i s consi dered i n t heopti m al grade transi ti onm odel because M FRdi rectl y refl ects the di stri buti oni nm ei ti ndex anddeusi ty[ Slapol ym er，form ul ti stageol 胡npol ym eri zati on reac-sol uti on areti m e．consum i ng．ofal l ，m el tfl ow rati oRecei ved2002· 02- 11，accepted 2002- 11- 08．Tow homcorrespondenceshoul d be addre"ed．E-m ai l ：yryangO m ai l ．hz．羁j ．cn’ 万方数据
