ti: Sn xut para-xylenMc LcPhn 1. M u Phn 2. Ni dung 2.1. Tnh cht k thut ch yu ca para-xylen 2.2. Cc ngun sn xut chnh 2.2.1. Cc ngun t du m 2.2.1.1. T qu trnh reforming xc tc 2.2.1.2. T qu trnh Cracking hi nc 2.2.1.3. T qu trnh chuyn ha Hydrocacbon 2.2.2. Ngun t than 3 4 4 5 6 6 7 8 92.3. Cng ngh sn xut p-xylen t sn phm ca qu trnh reforming xc tc 11 2.3.1. X l nguyn liu Naphta 2.3.2. Qu trnh reforming xc tc 2.3.2.1. B phn phn ng 2.3.2.2. B phn ti sinh xc tc 2.3.2.3. B phn n nh 2.3.2.4. Xc tc cho CCR Platforming 2.3.3. Tch p-xylen t sn phm reformat 2.3.3.1. Phn xng Tatoray 2.3.3.2. Phn xng Isomar 11 12 13 14 16 23 25 25 291 ti: Sn xut para-xylen 2.3.3.3. Phn xng Parex Phn 3. Kt lun Ti liu tham kho 32 39 402 ti: Sn xut para-xylenPhn 1. Li M uPara-Xylen hay 1,4-dimetyl benzen l mt trong nhng ng phn c nhiu ng dng quan trng trong s cc ng phn ca xylen C6H4(CH3)2, Para-Xylen c s dng trong cng nghip ch yu sn xut axit terephtalic v dimetyl terephtalat, y l cc nguyn liu u cho vic sn xut s si, mng polieste v nha PET c ng dng rng ri trong mi lnh vc i sng x hi. y l sn phm cn t c sn xut trong nc3 ti: Sn xut para-xylenPhn 2. Ni Dung2.1. Tnh cht k thut ch yu ca para xylenPara xylen c khi lng phn t l 106,16 vC, si 138,40C, im nng chy nhit 13,30C, tn ti dng lng khng mu hay dng tinh th. Para xylen l cht c d bt chy, tan tt trong etanol v t tan trong nc. Mt s tnh cht khc trong bng 1.Bng 1: Mt s c trng k thut ca BTX v cumen [1]Thng sn vBenzen 78,11Toluen 92,13Khi vC lng phn t T trng 200C Nhit 0C nng chy Nhit 0C si Gii hn % th n trong tch khng kh Trn Dio-xylen mxylen 106,16 106,16p-xylen etylbenzen 106,16 106,170,879 5,330,867 -94,990.876 -25,20.86 -480.857 13,30.867 -94,980,1110,6144,4139138,4136,21,4 7,11,3 6,81,1 6,41,1 6,41,1 6,60,99 6,74 ti: Sn xut para-xylenNhit 0C chp chy cc kn T trng 2,77 hi(khng kh=1) Gii hn tip xc (ppm; gi) -11,1 4,4 17,2 25 25 153,143,73,73,73,73,75;850;8100;8100;8100;8100;82.2. Cc ngun sn xut chnhCc ng phn xylen trong t nhin thc t ch c trong du m. Tuy nhin hm lng ca chng trong du m cn ph thuc nhiu vo v tr a l cng nh tui ca du th. [Bng 2] so snh hm lng ca hydrocacbon thm C8 v C6-C8 nhiu loi du m khc nhau trn th gii. Bng 2: Hm lng Hydrocacbon thm trong cc loi du m. [2]Libi Hydrocacbon 0,56 C8, % khi lng Hydrocacbon 1,0 C6-C8, % khi lng Vnh ng Louisiana Texas 0,5 1,10 Venezuela Negiria 1,10 1,47 Iran 1.051,101,791,852,501,80D vy cng c mt vi trng hp trong du m (vd: du m ng Nam ) cha hm lng ln hydrocacbon thm (ln ti 35%). Nhng phng php tc ly xylen t nhin l khng c tnh kinh t.5 ti: Sn xut para-xylen 2.2.1. Cc ngun t du m 2.2.1.1. T qu trnh Reforming xc tc Hn hp xylen ni chung, cng nh p-xylen ni ring ch yu c tch t sn phm ca qu trnh reforming xc tc, vi nguyn liu u l thng l phn on napthta. Trc khi i vo qu trnh th nguyn liu cn phi c x l tp cht c bit l lu hunh, v lu hunh rt nhy cm ti h xc tc Pt Re ca qu trnh reforming. Thnh phn cng ca sn phm reformate cng nh hm lng ca pxylen ph thuc rt nhiu vo cch tin hnh qu trnh reforming cng nh l loi nguyn liu naphta c s dng. Thnh phn ca phn on naphtha c bit l hm lng naphthen hay cc hydrocacbon thm c nh hng ln nht n n cht lng ca sn phm reformate thu c. Trn thc t naphtha thu c t qu trnh chng du naphtenic th s ph hp nht cho qu trnh reforming sn xut hp cht thm. Tuy nhin phn on naphtha c sn xut t qu trnh hydrocracking thng cng thu c giu hm lng naphthen nn rt ph hp lm nguyn liu u cho qu trnh reforming sn xut cc ng phn xylen. Bn cnh thnh phn, khong nhit si ca naptha nguyn liu cng nh hng n hiu xut thu c xylen. Bng 3: S ph thuc ca thnh phn reformate vo nhit si ca nguyn liu u vo [2]Khong nhit si ca Naphtha, 0C 60-160 107-160 90-160 Thnh phn ca nguyn liu, % khi lng Paraffin Naphten Hydrocacbon thm Thnh phn hydrocacbon thm trong Reformat, % khi lng Benzen69,6 19,5 10,962,2 21,2 16,664,2 22,2 13,69,31,65,26 ti: Sn xut para-xylenToluen Hydrocacbon thm C8 Hydrocacbon thm C9+ 21,7 20,8 8,8 19,0 34,3 15,2 25,1 26,2 11,2Nh s liu trong bng, khong nhit si thch hp nht ca Naphtha lm nguyn liu Reforming sn xut para xylen l t 106 n 160 0C. 2.2.1.2. T qu trnh Cracking hi nc ( Xng nhit phn) Xng nhit phn c thnh phn t C5 tr ln l sn phm ca qu trnh cracking hi nc cc phn on lng. Thnh phn ca xng nhit phn c cha hm lng ln cc hydrocacbon thm, c bit l benzen, v mt lng tng i cc ng phn xylen. Chnh v vy y cng l mt ngun ng gp sn phm c gi tr co cho c cng ngh sn xut xng cng nh cng ngh tng hp hu c ha du. Sn lng xng nhit phn cng nh hm lng cc ng phn xylen trong c quyt nh bi nguyn liu s dng v iu kin tin hnh sn xut. Bng 3: nh hng ca nguyn liu u vo n lng xng nhit phn v lng hydrocacbon thm C8 t cracking hi nc trong iu kin khc nhit vi dng C2, C3 tun hon [2]Nguyn liu Sn lng xng nhit phn (C52000C), % 1,7 6,6 7,1 18,7 18,4 19,3 Sn lng Hydrocacbon thm C8, % Phn hydrocacbon thm C8 trong xng nhit phn, %Etan Propan Butan Naphtha c nhit si trung bnh Du chng p sut kh quyn Du chng p sut chn khng0,4 1,8 2,2 1,95,6 9,6 12,0 9,87 ti: Sn xut para-xylen Sn phm xylen t xng nhit phn l sn phm ph ca qu trnh sn xut etylen v propen, tuy nhin trong mt s trng hp vic tch cc ng phn xylen li mang li hiu qu v mt kinh t. Vic iu chnh iu kin sn xut tuy khng ti a ha sn lng ca xylen nhng cng c nh hng ng k, c th l nu tng nhit phn ng, gim thi gian lu, gim thi gian lu bng cch tng lng hi vo th s lm gim ng k lng xng nhit phn thu c, tuy nhin hm lng ca xylene trong li tng ln.Bng 4: nh hng ca iu kin phn ng (thnh phn etylen trong sn phm) ca qu trnh cracking hi nc n nng xut v thnh phn ca xng nhit phn [2]iu kin (% Etylen) Xylen + Etylbenzen (trong tt c cc sn phm), % khi lng 0,9 1,6 1,7 Xylen + Etylbenzen trong xng nhit phn, % khi lng 3,5 7,2 10,7Thp (24,4) Trung binh (28,5) Cao (33,4)2.2.1.3. Cc qu trnh chuyn ha Hydrocacbon a. Isome ha V p-xylen l ng phn c gi tr nht xn xut s si tng hp nn bn cnh vic thu nhn n t qu trnh tch hn hp ng phn xylen bng kt tinh phn on hoc hp ph, hiu sut p-xylen cn c tng cng nh qu trnh isome ha o-, m-xylen v c etylbenzen. b. Phn b li Toluen Qu trnh ny c pht trin thnh quy m cng nghip nhm mc tiu tng sn lng benzen v hn hp xylen trn c s chuyn ha toluen t c gi tr ng dng hn. Bng cch kt hp vi qu trnh8 ti: Sn xut para-xylen phn tch p-xylen theo phng php kt tinh hoc hp ph, hoc kt hp Isome ha, cng ngh ny c th c s dng sn xut lng tng i ln o-, p-xylen m khng cn tng lng reformat x l. c. Qu trnh Cyclar Bn cht qu trnh Cyclar l chuyn ha c xc tc LPG, mt hn hp ca propan v butan, thnh sn phm giu hydrocacbon thm. Giai on u tin c gi thit l phn ng dehydro ha ca propan v butan thnh cc olefin tng ng. Tip , cc olefin ny s oligome ha thnh cc olefin C6, C7 v C8. Phn ng tip theo l dehydro vng ha to thnh cc hydrocacbon thm BTX. Mc d olefin l cc hp cht trung gian ca qu trnh ny nhng sn phm cui cng ca qu trnh c nng olefin rt thp. Ton b qu trnh phn ng l thu nhit do tnh tri ca phn ng dehydro ha v cracking. Metan v etan l cc sn phm ph hnh thnh t phn ng Cracking. Hiu sut hydrocacbon thm t 63-66% ty thuc vo thnh phn nguyn liu. Thnh phn sn phm lng cha ti 92% khi lng BTX, 7-8% hydrocacbon thm C9 v C10, v rt t lng hydrocacbon khng thm. Nu ch s dng propan lm nguyn liu th lng hydrocacbon thm C8 thu c l 17,3% khi lng, cn s dng butan th thu c 19,8% khi lng hydrocacbon thm C8. Lng xylen thu t qu trnh ny t c khong 15% khi lng nguyn liu a vo.2.2.2. Ngun t than . Du nh, c hnh thnh nh l sn phm ca qu trnh cacbon ha than (cc ha) nhit cao, c cha khong 60% benzen v 1220 % toluen. Trong iu kin cc ha 10000C, khng c khng kh, s xy ra cc qu trnh chuyn ha su (phn hy nhit v thm ha) phn hu c ca than to thnh cc, cc sn phm lng v kh. Do thanh ngho hydro hn so vi du m nn hiu sut sn phm cc9 ti: Sn xut para-xylen to thnh (70-80%) ln hn rt nhiu so vi sn phm lng (4-5%). Tuy nhin, v qu trnh cc ha din ra nhit cao nn sn phm lng c thm ha hon ton (95-97%), v vy lng hydrocacbon thm l rt ng k. Cc sn phm hydrocacbon thm hnh thnh t qu trnh phn hy nhit v thm ha phn hydrocacbon ca than l benzen, toluen, xylen, thiophen, pyridin Cc hydrocacbon thm c th c tch ra nh qu trnh hp th ngc dng bng phn on du m c nhit si cao, khong 300-4000C. Hn hp c chng tch trong thp chng ct li cun hi nc lin tc. Cc hydrocacbon nh c tch ra nh qu trnh chng ct v sn phm th c ra bng dung dch axit sunfuric c loi b hon ton cc hp cht lu hunh, cc hydrocacbon c tip tc chuyn v b cha, trung ha ht phn axit d v ra li bng nc. Qu trnh hydro ha loi b cc cht lu hunh, nit v cc hp cht khng no cn li. Benzen c tch ra t phn on hydrocacbon thm nh qu trnh chng trch ly vi dung mi sunfolan. Cc ng phn xylen c tch ra tng t so vi i t qu trnh Reforming xc tc. Cng ngh sn xut hydrocacbon thm i t sn phm lng ca qu trnh cc ha than trn thc t ch ph bin khi du m cha c bit n v khai thc. Ngy nay cng ngh ny ch cn c s dng trng mt s nh my Nam Phi v Niudiln.10 ti: Sn xut para-xylen2.3. Cng ngh sn xut p-xylen i t sn phm ca qu trnh Reforming xc tc.S tng qutX l nguyn liu NaphtaQu trnh Reforming xc tcTch p-xylen t sn phm Reformat2.3.1. X l nguyn liu NaphtaTrong nguyn liu u hydrocacbon c cha cc hp cht lu hunh c th gy ng c cho xc tc ca qu trnh chuyn ha, v vy cc hp cht cha lu hunh cn phi c lm sch khi nguyn liu u. Cc hp cht lu hunh c chuyn sang dng H2S bng qu trnh Hydrodesulfua ha (HDS) vi xc tc Co-Mo/Al2O3. Sau H2S c hp ph bng ZnO (b mt ring 25 m2/g) H2S + ZnO = ZnS + H2O Hm lng lu hunh c gim xung mc nh hn 0,01 ppm. Cc hp cht clo gy n mn cc thit b trao i nhit v gy ng c xc tc kh ha nhit cng c lm gim xung mc di 5ppb s dng cht hp ph Al2O3 c x l vi kim.11 ti: Sn xut para-xylen2.3.2 Qu trnh Reforming xc tcHnh 1: S cng ngh CCR Platforming ca UOP [3]Cng ngh CCR Platforming ca UOP vi cc thit b phn ng chng ln nhau thnh mt khi. Xc tc chuyn ng t thit b phn ng trn xung thit b phn ng di cng, sau xc tc lm vic c chuyn sang thit b ti sinh khi phc li hot tnh ri np li thit b phn ng th nht to thnh mt chu k khp kn.12 ti: Sn xut para-xylen 2.3.2.1. B phn phn ng Nguyn liu trn vi kh H2 tun hon c t nng n nhit phn ng trong thit b trao i nhit v b phn th nht ca l ri c np vo thit b phn ng th nht ( trn cng). Sau khi tip xc vi xc tc, nguyn liu b bin i ty thuc vo kht khe, cc iu kin cng ngh ca qu trnh, to nn sn phm c tr s octane cao hn hay hydrocarbon thm nhiu hn. Khi thit b phn ng gm c 3 4 thit b chng ln nhau theo trc thng ng. Kch thc tng dn t trn xung di v u l kiu xuyn tm. Trong mi thit b phn ng c thit k ring v ng dn xc tc, b phn phn phi, b phn cch ly v cc thit b khc sao cho ph hp vi qu trnh chuyn ng ca xc tc v cc phn ng ha hc xy ra. Lng xc tc trong thit b phn ng rt khc nhau, trong khi thit b phn ng th nht ch cha 10 20% lng xc tc th thit b phn ng cui cng cha n 45% xc tc. T l phn b xc tc trong cc thit b phn ng vi s 4 thit b phn ng thng theo t l 1 : 1,5 : 3 : 4,5. Xc tc lm vic chuyn sang l ti sinh xc tc, hn hp hi-kh phn ng i ra khi thit b phn ng th nht c qua l t nng li nhit n nhit phn ng ri c np ngay vo thit b phn ng th hai. C nh vy cho n thit b phn ng th 4. Sau , hi-kh sn phm c lm lnh do trao i nhit vi nguyn liu ri ngng t v lm lnh tip trc khi chuyn sang b phn phn tch sn phm. thit b tch, sn phm c chia13 ti: Sn xut para-xylen thnh hydrocarbon lng ngng t v kh giu H2. Mt phn kh ny c quay li thit b phn ng nh my nn kh tun hon, phn cn li c trn vi b ti tip xc ri i vo ct n nh sn phm. 2.3.2.2. B phn ti sinh xc tc Xc tc lm vic chy t y ca thit b phn ng cui cng xung b phn thu xc tc bunke cha sau n chy xung ng nng. Ngi ta dng kh H2 tun hon t my nn y xc tc v vn chuyn n ln nh vo b phn phn tch bi pha trn l ti sinh. b phn tch ny, ngi ta b sung thm mt lng kh H2 tun hon tch cc ht bi mn ca xc tc v mang chng ra ngoi vi kh vo ng tp trung bi, cn xc tc ri xung y b phn tch bi ri chy xung l ti sinh. Ti sinh xc tc gm 5 bc: ui hydrocarbon ra khi xc tc bng kh tr, thi khng kh nng vo t cc, tin hnh clo ho xc tc nhm tng hot tnh xc tc, sy cht xc tc, ui ht O2 ra khi xc tc bng lung kh tr N2 sau tin hnh hydro ho chuyn t mi trng oxy ho sang mi trng kh. t chy cc bm trn b mt xc tc c tin hnh trong vng chy nh l ti sinh. Xc tc c a vo v chy xung pha di gia mng chn hnh tr t thng ng, khng kh nng c thi theo hng bn knh i t pha ngoi vo trong qua lp xc tc. Kh chy nng c thi nh bm, sau lm lnh v tun hon qua cc ng trong vng chy. t chy cc vn xy ra trong khi xc tc14 ti: Sn xut para-xylen vn chuyn ng xung pha di, b phn lm lnh ti sinh s ly nhit khi t cc. Cn b phn t nng ti sinh s lm vic khi cn phi t nng kh m bo nhit pha trong vng thch hp. Qu trnh oxy ha, phn tn kim loi trn xc tc v b sung thm clo c thc hin trong vng clo ha ca l ti sinh b tr di vng chy. Xc tc ri xung theo cc lp hnh tr, kh clo ha nng c thi qua lp xc tc v i ra vng chy, t vng sy kh thi qua cc ng vng trn i vo vng clo ha. Hp cht clo hu c c phun vo khng kh dn vo vng clo ha v cng c t nng b phn gia nhit ring m bo nhit vo. Sy kh khng kh c thc hin vng sy. Vng sy nm pha di vng clo ha, kh kh nng c thi qua lp xc tc v tch m. Vic t nng kh kh c thc hin bi l t khng kh.Qu trnh kh kim loi trn xc tc xy ra vng kh. Vng kh t pha di v tch bit khi ba vng trn. Kh kh nng c thi qua lp xc tc. H thng tinh ch s tch cc hydrocarbon nh t kh ny v lm tng tinh khit ca H2. Kh kh c t nng nh l t nng ring m bo cho nhit vo vng kh. Sau khi kh, xc tc c a theo ng dn xc tc vo ng nng th hai, tc chy c khng ch m bo chu trnh kh v ti sinh xy ra. Tip theo xc tc c kh H2 vn chuyn v nng ln bunke cha t pha trn ca nh thit b phn ng th nht, tip tc chuyn ng vo cc thit b phn ng lm vic. Chuyn ng ca xc tc t thit b phn ng ny xung thit b phn ng khc15 ti: Sn xut para-xylen c khng ch v phn phi qua tm ng dn hay nhiu hn m bo iu ha, phn phi u, trnh chy tho xc tc hay t qung lp xc tc. 2.3.2.3. B phn n nh Thp n nh s tch hydrocarbon nh v thu c reformate n nh. Sn phm reformate n nh c cho qua thit b trao i nhit vi nguyn liu ri cho vo b cha. a. B phn thit b phn ng B phn thit b phn ng c cc thng s cn ch sau: + Nhit . + Tc truyn nguyn liu theo th tch. + p sut thit b phn ng. + T s H2/RH. Nhit thit b phn ng Khi nhit thit b phn ng tng, tr s ca octane tng ln v nng sut ca sn phm xng gim xung. Do vy thit b phn ng cn gi mc nhn sn phm c tr s octane mong mun v khng nn cao hn.16 ti: Sn xut para-xylen Tc truyn nguyn liu Tc truyn nguyn liu theo th tch c nh hng nhiu n cht lng sn phm. VVH cng cao th cht lng sn phm cng thp. Khi mun b li s gim cht lng sn phm, ta c th tng nhit ca thit b phn ng. Khi VVH thp, cc phn ng ph li xy ra v iu lm gim nng sut ca reformate.iu cn thit l nn gim nhit vo ca thit b phn ng trc khi gim tc np liu m khng nn lm ngc li, nu khng s tng tc hydrocracking, dn n tiu hao nhiu H2 v khi qu trnh to cc trn xc tc s xy ra nhanh hn. p sut thit b phn ng p sut trong thit b phn ng nh hng n hiu sut v cht lng ca reformate, n nhit thit b phn ng v n n nh ( bn) ca xc tc. p sut thit b phn ng v mt l thuyt khng hn ch, tuy vy khi thit k cn phi c gii hn m bo khng nh hng xu n cc ch tiu kinh t. Gim p sut ca thit b phn ng s lm tng nng sut ca H2 v nng sut ca reformate, gim nhit thit b phn ng cn thit m gi vng cht lng sn phm, nhng dn n chu k lm vic ca xc tc ngn hn do tng lng cc bm trn b mt xc tc. T l H2/RH17 ti: Sn xut para-xylen Tun hon H2 trong h thng CCR l cn thit gi xc tc n nh v hot tnh. Cc nguyn nhn dn n tng t l mol H2/RH: Kh tun hon qu nhiu. Tc np nguyn liu vo thit b phn ng gim thp hn khi tc tun hon khng i. p sut thit b phn ng tng ln. l nhng bin php v cc du hiu kim tra t l H2/RH. Tuy nhin c mt s tnh hung c th lm thay i t l m khng phi do thay i iu kin thao tc t trc, l: + Gim tinh khit ca H2 trong kh tun hon. + Tng kh nng tt t ngt p sut. + My nn km hiu qu v cc nguyn nhn v c kh. S to cc Trong qu trnh sn xut, khi thao tc khng kp ti sinh, mc lng ng cc trn b mt xc tc tng ln v n mc phi tho xc tc ra rt nhanh ti sinh, lm nh vy dn n hu qu xu l: + Lm gim nng sut reformate. + Lm gim nng sut H2. + Tng nhit thit b phn ng n nhit cc i.18 ti: Sn xut para-xylen + Tng nhit t nng. Tng tc lng cc v tng mc carbon cn bng (lng carbon cn li xc tc ti sinh) l do cc nguyn nhn sau: + Tng nhit ca xc tc. + Gim p sut ca thit b phn ng. + Gim t l mol H2/RH. + Nguyn liu np vo c im si cui cao, nhiu cu t nng. + Tng tc np liu qu ln. + Cht lng ca nguyn liu thp (tng N + 2A thp). Nu tip tc vn hnh mc carbon cn bng cao s gim thi gian lm vic xc tc. Khi cc lng ng trn b mt xc tc s lm xut hin cc hin tng sau: + Cht lng ca sn phm RON gim thp khi nhit ca thit b phn ng v tc np nguyn liu khng thay i. + tt nhit tt c cc thit b phn ng u gim xung so vi thit k. + Gim kh tch ra. + Nng H2 trong kh tun hon gim.19 ti: Sn xut para-xylen + Cht lng reformate gim. Xc tc lm vic c chuyn sang ti sinh loi b cc cc bm trn b mt xc tc v tr li hot tnh cho xc tc. Ty thuc vo iu kin vn hnh ca qu trnh reforming xc tc m thi gian lm vic ca xc tc c th t t 2 5 nm. b. B phn ti sinh xc tc Nhng thng s quan trng nht ca vng ny gm: + Tc tun hon xc tc. + Hm lng oxy trong vng chy. + Hm lng cc bm trn xc tc lm vic. + Tc kh ti sinh. Trn thc t, ngi vn hnh cn phi kim tra thc t hai ch tiu l tc tun hon xc tc v hm lng oxy trong vng chy. Cn hai ch tiu khc l lng cc bm trn xc tc v tc kh ti sinh khng cn kim tra trc tip m ch qua phn tch xc nh lng cc bm trn xc tc, t quy nh tc kh ti sinh v nng oxy trong vng ti sinh m bo sau khi ti sinh lng cc ch cn 0,2% khi lng trn xc tc.20 ti: Sn xut para-xylen Oxy trong vng chy Ngi vn hnh kim tra lng oxy trong vng chy khi s dng my phn tch oxy. Khi vn hnh bnh thng, my phn tch oxy s cho bit lng d khng kh c thi t thp ti sinh l bao nhiu. Khong nng thch hp ca oxy trong vng chy 0,5 0,8%mol. Nu nng oxy cao hn s lm cho qu trnh chy mnh lit hn dn n tng nhit qu cao nguy hi cho xc tc v cc trang thit b trong vng ny. Nu nng oxy qu thp s lm gim qu trnh chy cc v khng tch ht lng cc cn tch, hay ni cch khc l khng th hon thnh qu trnh chy trong vng ny. Lng cc bm trn xc tc lm vic Nhng iu kin vn hnh ca thit b phn ng nhm kim tra v khng ch lng cc bm trn xc tc lm vic. Hm lng cc l mt hm s ca tc truyn nguyn liu, tr s octane ca sn phm, cht lng nguyn liu, p sut thit b phn ng, tc tun hon H2 v tc vn chuyn xc tc. Khi thao tc thng thng s c 3 7%m cc bm trn xc tc, ch trong khong ny cht lng xc tc v thi gian lm vic ca xc tc mi l thch hp nht. Bin php nh gi lng cc bm trn xc tc cho php hiu rng iu kin vn hnh nh vy c cho php hay khng. Lng cc cho php ti a trn xc tc c xc nh t ng cong vn hnh chung nh c ch ra nh v d sau: Nu iu kin vn hnh b ti sinh l:21 ti: Sn xut para-xylen + Tc vn chuyn xc tc: 100% theo thit k. + Oxy trong vng chy: 0,8%mol. + Chiu di vng chy: 90% ca thit k. th hm lng cc cho php cc i l 5,4%m so vi lng xc tc . Nh vy phi iu chnh iu kin vn hnh ca l phn ng gii hn hm lng cc bm trn b mt xc tc ti a l 5,4% khi lng. Nhit ca cc lp trong vng chy Cc iu kin vn hnh trong b phn ti sinh c m bo khi khng ch cht ch nhit tng lp trong vng chy. Nhit ny s cho bit du hiu tt hay xu ca s chy cc trong vng. T nh ti y ca vng chy, nhit ca cc lp s to thnh mt hnh nh rt r rng v tc ca qu trnh. Thng thng c ba quy lut chung lin quan n hnh nh thay i nhit ca cc lp: + Nhit cc i (nh ng cong) s nm trong khong 40% k t nh ca vng chy xung pha di. Khi tc chy l ln nht. + nh nhit khng xut hin m c hai u vng chy nhit nh nhau. iu ny chng t s chy cc ch yu l y vng chy.22 ti: Sn xut para-xylen + S thay i khc nhau ca ng cong nhit s bo ng cho ngi vn hnh bit thay i cc thng s vn hnh trong thp ti sinh. Cc i ca nh nhit lp thng l 5390C. Nu vt qu nhit ny s ph hng lp xc tc, thm ch cn nguy him cho trang thit b khc ca thit b ti sinh. Vng kh Vng kh c vn hnh bng cch t ng iu khin cc thng s cng ngh trnh xy ra cc hin tng n do s xm nhp ca kh H2 v kh chy hay oxy trong vng chy. 2.3.2.4. Xc tc cho CCR Platforming Xc tc th h mi nht ca cng ngh CCR Platforming ca UOP l R-254 v R-284, vi cc u im ni tri nh: sn lng cao, hot tnh tt, lng cc to thnh thp v n nh cao. Xc tc ngy nay l xc tc lng chc nng. Thnh phn ca xc tc l Pt- Re/ Al2O3 vi 0.3% Pt + 0.3% Re mang trn - Al2O3, vi din tch b mt khong 250m2/g, c b sung thm cc hp cht halogen hu c. Hm lng Clo thm vo khong 0.5 n 1% trng lng. Vai tr ca tng thnh phn Pt: ng vai tr kim loi trong xc tc, l pha hot ng tng tc phn ng. Mang chc nng oxi ha kh, xc tin cho cc qu trnh to vng thm, loi nguyn t d th S,N,O.23 ti: Sn xut para-xylen Re: thm vo to thnh xc tc a kim loi, lm h gi thnh xc tc, ko di bn hot ng ca xc tc. c bit, chng c vai tr lm phn tn u cc nguyn t Pt ln trn b mt axit rn. T , lm cho hiu sut qu trnh c tng cao. Al2O3 : ng vai tr chc nng axit trong xc tc, thc u phn ng izome ha. Yu cu i vi xc tc Xc tc phi c chn lc cao Phi c bn nhit v kh nng ti sinh tt Xc tc phi b vi cc cht gy ng c C n nh cao C gi thnh hp l, d ch to.24 ti: Sn xut para-xylen2.3.3. Tch para-xylen t sn phm Reformat. S cng nghHnh 2: T hp sn xut cc hp cht thm ca UOP [3] 2.3.3.1. Phn xng Tatoray Trong cng nghip ha du, do toluen c t gi tr ng dng, ngi ta thng chuyn ha toluen tng sn lng benzen v hn hp xylene thng qua vic phn tch p-xylene theo phng php kt tinh hoc hp ph. Cng ngh ny thng c s dng sn xut mt lng ln o-xylene v p-xylene m khng cn tng lng reformate cn x l.25 ti: Sn xut para-xylen Phn ng chnh xy ra: 2C6H5CH3 C6H6 + C6H4(CH3)2 Hoc phn ng chuyn nhm alkyl nu c trimetyl benzen trong thnh phn nguyn liu u: C6H5CH3 + C6H3(CH3)3 2C6H4(CH3)2 Phn ng ny c s dng iu chnh t l benzen/C8 bng cch a vo hn hp nguyn liu cc hydrocacbon thm C9 c tch trong qu trnh x l phn on C8. S cng nghHnh 3: S cng ngh Tatoray ca UOP [3]Cng ngh Tatoray bao gm 1 thit b phn ng loi tng c xc tc c nh v 1 thp tch sn phm. Nguyn liu u vo gm Toluene v C9 c kt hp vi ngun kh tun hon giu hydro c gia26 ti: Sn xut para-xylen nhit trc bi thit b trao i nhit. V mt l thuyt, qu trnh c th tin hnh m khng cn s c mt ca hydro, nhng s c mt ca n hn ch s to cc. Sau , hn hp s c nng ln n nhit phn ng thit b t nng. Sau , hn hp hi c a vo thit b phn ng chnh loi tng c lp xc tc c nh. Dng ra sau c lm lnh qua thit b trao i nhit vi ngun lnh chnh l hn hp vo. Dng sn phm trc khi vo thp tch cn c cho qua thit b ngng t. Kh giu hydro c ly ra pha trn nh thp, mt phn nh ca n c lc tch loi cu t nh v quay tr li i v trn vi nguyn liu u. Dng lng pha di ca thp tch c chuyn qua thp tch kh lng. Sn phm nh ca thit b c lm lnh sau c tch ra mt phn l kh, 1 phn l lng. Phn kh bao gm cc cu t nh c chuyn qua h thng kh nhin liu. Sn phm lng nh th c chuyn qua phn xng Platforming thp debutan. Dng Benzen trong dng ny th c tch ra v chuyn sang b phn tch benzene toluene. Benzen v cc ng phn xylene, cng vi toluene cha phn ng v hydrocacbon thm C9, c ly t y thp tch Stripper s tun hon chuyn n b phn tch benzene-toluen. iu kin cng ngh T l mol H2/hydrocacbon = 5-20 Nng hydro trong dng kh tun hon >70% p sut: 3-4 MPa Nhit tng t 410 n 470OC Xc tc27 ti: Sn xut para-xylen Xc tc th h mi nht ca qu trnh Tatoray l T-20 l xc tc zeolite c cha 1,25% Cr v 0.5% Mo. Vic ci tin to nn rt nhiu u im cho xc tc ny: Tnh n nh cao hn Hot tnh cao hn Khng thay i cc iu kin m h thng yu cu chuyn ha v sn lng tng Khng cha kim loi qu Cht lng benzene cao, tinh khit C th ti sinh iu kin tin hnh:Hnh 4: Sn lng p-Xylene thu c ti a cc iu kin qu trnh Tatoray [3]28 ti: Sn xut para-xylen Da vo hnh trn ta c th thy, nu nhit dng vo l 170OC th sn lng p-Xylene thu c s ln nht: 420 KMTA.2.3.3.2. Phn xng IsomarPhn xng UOP Isomar c s dng thu ti a mt ng phn xylen no trong hn hp ng phn hydrocacbon thm C8. Thng thng Isomar ch yu c s dng tn thu ti a p-xylen nhng n cng c th s dng thu hi c o-, m-xylen. Trong trng hp thu hi p-xylen th nguyn liu ca qu trnh ny l phn raffinat ca phn xng Parex, ni m p-xylen c thu hi ti 97% v c tinh khit ln ti 99% khi lng. Phn Raffinat cn li ch yu gm m-xylen v etylbenzen mt lng nh cn li l p- v oxylen. y hiu sut ca p-xylen c tng cng nh qu trnh isome ha cc ng phn m-,o-xylen v c etylbenzen. Isome ha to ra s chuyn ha lin tc v dn n cn bng gia 4 loi hydrocacbon thm C8 theo s sau: Cc phn ng chnh Phn ng Isome ha xylen Phn ng Isome ha Etylbenzen29 ti: Sn xut para-xylen Xc tc ca qu trnh Xc tc dng cho qu trnh ny l xc tc lng chc, chc axit (zeolit) v chc kim loi. Chc nng ca chc axit l isome ha cc ng phn xylen to thnh mt hn hp cn bng ng. Chc kim loi ch yu thc y cc phn ng hydro ha v hydro ha, gp phn chuyn ha etylbenzen thnh cc ng phn xylen. Theo dy chuyn ca UOP ti a ha lng p-xylen thu c h a ra mt lot cc mu xc tc nh I-9, I-210, I-400 Dy chuyn cng nghHnh 5: S cng ngh UOP Isomar [2] Mt phn xng Isomar thng thng s lun i cng vi mt phn xng thu hi mt hay nhiu ng xylen. V hu ht cc phn xng Isomar thng i cng vi phn xng Parex thu hi p-xylen. Hn hp xylen nguyn liu vo phn xng Parex c a ti thp chng ct xylen, y l b phn thit k khng nhng thu c o-xylen y thp m cn n gin loi b c cc hydrocacbon thm C9+ p ng c cc ch tiu nguyn liu ca phn xng Parex. Cn sn phm nh ca thp chng xylen s c a thng vo qu trnh Parex ni m c th thu hi 97% lng p30 ti: Sn xut para-xylen xylen v sn xut c p-xylen vi tinh khit 99,9%. Cn sau sn phm Raffinat ca qu trnh Parex, cha hm lng p-xylen di 1% c a sang qu trnh Isomar. Dng nguyn liu ca qu trnh Isomar u tin phi trn vi dng kh giu Hydro tun hon v lun c b vo lng Hydro mt i do phn ng ca qu trnh Isomar. Sau dng nguyn liu c gia nhit bi dng sn phm ra t thit b phn ng, tip theo chng c bc hi trong thit b nung nng, nhit c nng ti nhit phn ng. Dng kh nng c a vo thit b phn ng ri i qua cc lp xc tc c nh, thit b thng dng hng trc. Dng sn phm ra khi thit b phn ng c lm lnh khi trao i nhit vi hn hp nguyn liu u sau c a vo thit b tch sn phm. Dng kh giu hydro s c ly ra nh ca thp tch v tun hon li thit b phn ng. Mt phn ca dng kh c lm sch loi b phn nh ln vo trong dng kh tun hon. Phn lng y thp tch c a n thp chng loi b cc hp cht C7. Phn C7 nh thp ny c cng c lm lnh v a vo mt b phn tch kh lng, phn kh c s dng lm nhin liu cn phn lng th c tun hon li qu trnh UOP Platforming. Phn hydrocacbon C8 di y ca thp deheptan ha c x l bng vt liu t st loi b vt tp cht, cc loi nha v polime to thnh, sau tip tc tun hon v thp tch xylen. Cc ch tiu nguyn liu ca qu trnh Isomar Bng 5: Ch tiu nguyn liu ca qu trnh Isomar Tp cht Nc Tc hi Gii hn Tng n mn, gim 200 ppm, max hot tnh xc tc, khng ti sinh c Tng cng chc 2 ppm, max axit, tng phn ng cracking, c th ti sinh31Tng clo ti: Sn xut para-xylen Tng nit Trung ha vng axit, gim hot tnh xc tc, khng ti sinh c Gim hot tnh chc kim loi, tng phn ng cracking, c th ti sinh Lm ng c chc axit v chc kim loi, khng th ti sinh Lm ng c chc axit v chc kim loi, khng th ti sinh Lm ng c chc axit v chc kim loi, khng th ti sinh 1 ppm, maxTng lu hunh1 ppm, maxCh ng20 ppb, max20 ppb, maxAsen2 ppb, max2.3.3.3. Phn xng Parex UOP Parex l qu trnh s dng phng php tch vi h hp ph zeolit sng phn t thu hi p-X t hn cc ng phn xylen. Hu ht cc qu trnh Parex ngy nay c thit k sn xut p-X c tinh khit l 99,9 % khi lng v thu hi c trn 97 % lng a vo. Khng ging nh cc phng php sc k thng thng, qu trnh Parex m phng s chuyn ng ngc chiu nhau ca lng lng nguyn liu so vi lp cht hp ph tc c nh. Nguyn liu v sn phm vo v ra khi lp cht hp ph mt cch lin tc vi thnh phn gn nh khng thay i. K thut ny cn i khi gi l simulated moving-bed (MBA) lp hp ph gi chuyn ng.32 ti: Sn xut para-xylen Trong mt t hp sn xut hp cht thm hin i (Hnh 2), Phn xng Parex thng nm di thp tch xylen v thng i cng vi phn xng Isomar. Nguyn liu ca thp tch xylen cha sn phm hydrocacbon thm C8+ t qu trnh CCR* Platforming cng vi sn phm t phn xng Tatoray. Phn C8 t nh ca thp tch xylen c a thng ti phn xng Parex, ni m p-xylen c tinh khit cao c thu hi. Phn Raffinat ca qu trnh Parex sau c a sang phn xng Isomar, ni m cc ng phn C8 c chuyn ha thm thnh p-xylen v li tun hon v thp chng tch xylen. Trc khi qu trnh Parex c bin n, p-xylen ch yu ch c sn xut bng phng php kt tinh phn on. Trong phng php kt tinh, hn hp xylen c lm lnh xung khong -750C (1000F) ti im m p-xylen bt u kt tinh. Cc tinh th c tch ra khi nc ci bng my lc ly tm hay tch lc thng thng. Sau sn phm s c ra bi Toluen hay chnh mt phn sn phm pxylen. Nhng khong khng lu sau , nm 1971 cng ngh UOP Parex nhanh chng tr thnh cng ngh c la chn nht sn xut p-xylen. V t thi im hu nh tt c cc dy chuyn sn xut p-xylen da trn cng ngh UOP Parex. Li th chnh ca qu trnh Parex so vi phng php kt tinh l kh nng thu hi trn 97% lng p-xylen a vo. Cn cc phng php kt tinh cha cc hn hp -tec-tc nn lng p-xylen thu hi c ch t khong 65%. nh gi nguyn liu Hu ht hn hp xylen c s dng sn xut xylen c sn xut t naphta du m bi qu trnh reforming xc tc. Cng ngh UOP CCR Platforming hot ng iu kin cc k kht khe nn trong thnh phn C8+ ca phn Reformat hu nh khng cha cc tp cht khng thm. Nh cc ng phn hydrocacbon thm C8 c th a trc tip vo t hp thu hi xylen. Nhng cso trn mt33 ti: Sn xut para-xylen na tn lng hn hp xylen c sn xut t qu trnh chuyn ha ca toluen v hydrocacbon thm C9 trong qu trnh Tatoray. Cc tp cht khng thm trong nguyn liu ca qu trnh Parex ch lm tng nng lng tiu th v chim nhiu khng gian ch khng nh hng n tinh khit ca p-xylen sn phm. Nhng nguyn liu phi c tin hnh phn on trc tch hn hp hydrocacbon thm C8 v x l bng t st bo v cht hp ph. Bng 6: Ch tiu thnh phn nguyn liu ca qu trnh Parex [3]Thnh phn Para Xylen min, % khi lng Etyl Benzen max, % khi lng Toluen max, % khi lng Hydrocacbon C9+ max, % khi lng Hydrocacbon khng thm max, % khi lng Nit max, mg/kg Lu hunh max, mg/kg Axit Ch tiu 18 20 0.5 1.5 0.3 1.0 1.0 Khng c c34 ti: Sn xut para-xylen S dy chuyn cng nghHnh 6: S cng ngh UOP Parex [3] Cc qu trnh chia tch din ra trng cc thp hp ph. Mi thp hp ph c chia thnh cc lp cha cht hp ph. Mi lp hp ph c gn bi mt b phn phi c bit, mi b phn phi ny c ni chung vi mt van quay nh cc ng ni. B phn phi gia cc lp hp ph dng a cht lng vo v rt cht lng ra khi thp, cng nh thu hi cht lng a trn v phn phi cht lng cho a di. Thng thng mt Phn xng Parex c 24 lp hp ph v 24 ng ni mi lp n van quay chung. Nhng theo thc t kho st v ng gi mi Phn xng Parex c 2 thp hp ph mi thp c ch 12 lp cht hp ph. Qu trnh Parex thng c bn dng chnh c phn phi vo trong thp hp ph bi van quay l: Dng nguyn liu: Hn hp xylen vo Dng trch ra: Gm c sn phm p-xylen cng vi cht nh hp ph35 ti: Sn xut para-xylen Dng raffinat ra: Gm c etylbenzen, m-xylen, o-xylen, v cht nh hp ph Dng cht nh hp ph vo: Cht nh hp ph c tun hon t khu vc phn tch. Ti bt c thi im no cng ch c 4 ng dn hot ng a 4 dng ra v vo thp hp ph. Van quay c s dng chuyn theo chu k v tr ca lng vo v ra khi thp tng ng vi mi v tr c thnh phn xc nh dc theo thn thp. Mt bm c s dng bm cht lng t y thp 1 ln nh ca thp 2 v mt bm c s dng bm cht lng t y thp 2 nn nh thp 1. Nh vy 2 thp hp ph hot ng nh mt thp c ln lt tun hon tng lp cht hp ph. Dng trch t thp hp th c van quay a n thp chng tch sn phm ra khi cht nh hp ph. Sn phm nh ca thp c a sang thp cui cng tch loi bt c lng toluen no cn ln phi p-xylen tinh khit. Dng raffinat tng t cng c van quay a sang thp chng tch cht nh hp th. Sn phm nh ca thp l hn hp ng phn C8: etylbenzen; m-xylen; o-xylen cng vi bt c hp cht thm no cn ln phi trong nguyn liu vo. Sn phm raffinat li tip tc a sang qu trnh Isomar chuyn ha thnh p-xylen ri li tun hon v qu trnh Parex.36 ti: Sn xut para-xylenHnh 7: S cng ngh Parex kiu 1 thp hp ph [3]Hnh 8: M hnh thp hp ph vi lp cht hp ph chuyn ng [3]37 ti: Sn xut para-xylen Nh vy qua cc qu trnh: La chn nguyn liu naphta Tin hnh qu trnh reforming xc tc Phn b li Toluen bng phn xng Tatoray Isome ha xylen v etylbenzen trong phn xng Isomar Tch p-xylen bng qu trnh ParexTa c th thu hi c 97% p-xylen c tinh khit cao ti 99,9% v khi lng.38 ti: Sn xut para-xylenPhn 3. Kt lunThc t trn th gii cng ngh sn xut para xylen ngy cng hin i v dn t ti hiu xut ti a. Ngnh cng nghip sn xut para xylen l ngnh cng nghip mang li nhiu li nhun vi nhu cu tiu th hng nm lun tng. Cc sn phm sn xut t para xylen ngy cng c nhiu ng dng rng ri trong mi mt i sng x hi. Vi thc t Vit Nam th y l ngnh ang c b ng v giu tim nng pht trin39 ti: Sn xut para-xylenTi Liu Tham Kho [1] Phm Thanh Huyn, Nguyn Hng Lin. Cng ngh tng hp Hu c Ha du [2] Willey-VCH. ULLMANN'S Encyclopedia of Industrial Chemistry [3] Robert Meyers. Handbook of Petroleum Refining Process [4] http://www.uop.com/processingsolutions/refining/gasoline/#naphtha-reforming40