MC LC

NI DUNG Trang

MC LC24CHNG 1: TNG QUAN DU M V KH

41.1. Ngun gc

1.2.Thnh phn ha hc6CHNG 2: TNH CHT VT L C TRNG CA DU TH V PHN LOI DU M 132.1.Xc nh cc c trng vt l ca phn on du m 132.2.nh gi cht lng ca du m qua cc c trng sau212.3.Cc c tnh ca du th v sn phm du m252.4.Phn loi du m292.5.Thnh phn v phn loi kh30CHNG 3: CC PHN ON DU M V NG DNG CA CC PHN ON DU M 31Gii thiu: 313.1.Phn on kh323.2.Phn on xng373.3.Phn on kerosen483.4.Phn on gasoil nh513.5.Phn on gasoil nng (Phn on du nhn)533.6.Phn on cn du m (cn gudon)58CHNG 4: C S L THUYT CA QU TRNH CHNG CT 624.1.C s l thuyt624.2.Cc thng s cng ngh nh hng n qu trnh62CHNG 5: CC QU TRNH CHUYN HA HA HC DI TC DNG NHIT 645.1.S bin i ca cc hyrocacbon di tc dng nhit645.2.Qu trnh cracking nhit655.3.Qu trnh vibsreking675.4.Qu trnh nhit phn (pyrolyse)675.5.Qu trnh cc ha67CHNG 6: CC QU TRNH CHUYN HA HA HC DI TC DNG CA XC TC 686.1.Tnh u vit ca xc tc686.2.Qu trnh cracking xc tc716.3.Qu trnh reforming xc tc776.4.Qu trnh isomer ha806.5.Qu trnh alkyl ha82CHNG 7: S LC DU M V KH CA VIT NAM 847.1.Vi nt v ngnh du kh Vit Nam847.2.Tim nng ca du th Vit Nam85B Vng My867.3.Du th i din cho cc b trm tch Cu Long, Nam Cn Sn v Malay Th Chu 86TI LIU THAM KHO 90

CHNG 1: TNG QUAN DU M V KH

1.1. Ngun gc

1.1.1. Ngun gc v c

Theo gi thuyt ny trong lng Tri t c cha cc cacbua kim loi nh Al4C3, CaC2. Cc cht ny b phn hy bi nc to ra CH4 v C2H2:

Cc cht khi u (CH4, C2H2) qua qu trnh bin i di tc dng ca nhit , p sut cao trong lng t v xc tc l cc khong st, to thnh cc hydrocacbon c trong du kh. chng minh cho iu , nm 1866, Berthelot tng hp c hydrocacbon thm t axetylen nhit cao trn xc tc. Nm 1901, Sabatier v Sendereus thc hin phn ng hydro ha axetylen trn xc tc Niken v st nhit trong khong 200 3000C, thu c mt lot cc hydrocacbon tng ng nh trong thnh phn ca du. Cng vi hng lot cc th nghim nh trn, gi thuyt v ngun gc v c ca du m c chp nhn trong mt thi gian kh di.

Sau ny, khi trnh khoa hc v k thut ngy cng pht trin th ngi ta bt u hoi nghi lun im trn v:

phn tch c (bng cc phng php hin i) trong du m c cha cc Porphyrin c ngun gc t ng thc vt.

Trong v qu t, hm lng cacbua kim loi l khng ng k.

Cc hydrocacbon thng gp trong cc lp trm tch, ti nhit t khi vt qu 150 - 2000C (v p sut rt cao), nn khng nhit cn thit cho phn ng ha hc xy ra.

Chnh v vy m gi thuyt ngun gc v c ngy cng phai m do c t cn c.

1.1.2. Ngun gc hu c

l gi thuyt v s hnh thnh du m t cc vt liu hu c ban u. Nhng vt liu chnh l xc ng thc vt bin, hoc trn cn nhng b cc dng sng cun tri ra bin. trong nc bin c rt nhiu cc loi vi khun hiu kh v ym kh, cho nn khi cc ng thc vt b cht, lp tc b chng phn hy. Nhng phn no d b phn hy (nh cc cht Albumin, cc hydrat cacbon) th b vi khun tn cng trc to thnh cc cht d tan trong nc hoc kh bay i, cc cht ny s khng to nn du kh. Ngc li, cc cht kh b phn hy (nh cc protein, cht bo, ru cao phn t, sp, du, nha) s dn lng ng to nn lp trm tch di y bin; y chnh l cc vt liu hu c u tin ca du kh. Cc cht ny qua hng triu nm bin i s to thnh cc hydrcacbon ban u:

RCOOR + H2O RCOOH + ROH

RCOOH RH + CO2

RCH2OH R-CH=CH2 + H2O

R-CH=CH2 + H2 R-CH2-CH3

Theo tc gi Petrov, cc axt bo ca thc vt thng l cc axit bo khng no, s bin i to thnh -lacton, sau to thnh naphten hoc aromat:

Thuyt ngun gc hu c ca du m cho php gii thch c nhiu hin tng trong thc t. Chng hn nh: du m cc ni hu nh u khc nhau, s khc nhau c th l do vt liu hu c ban u. V d, nu vt liu hu c ban u giu cht bo th c th to ra loi du parafinic

Du c sinh ra ri rc trong cc lp trm tch, c gi l m. Do p sut y cao nn chng b y ra ngoi v buc phi di c n ni mi qua cc tng cha thng c cu trc rng xp. S di chuyn tip tc xy ra cho n khi chng gp iu kin thun li c th li y v tch t thnh du m.Trong qu trnh di chuyn, du m phi i qua cc tng xp, c th s xy ra s hp ph, cc cht c cc b hp ph v li cc lp , kt qu l du s nh hn v sch hn. Nhng nu qu trnh di chuyn ca du b tip xc vi oxy khng kh, chng c th b oxy ha dn n to cc hp cht cha cc d nguyn t, lm du b gim cht lng.

Khi du tch t v nm trong cc m du, qu trnh bin i hu nh t xy ra nu m du kn. Trong trng hp c cc khe h, oxy, nc kh quyn c th lt vo, s xy ra bin cht theo chiu hng xu i do phn ng ha hc.

Cc hydrocacbon ban u ca du kh thng c phn t lng rt ln (C30 C40), thm ch cao hn. Cc cht hu c ny nm trong lp trm tch s chu nhiu bin i ha hc di nh hng ca nhit , p sut , xc tc (l khong st). Ngi ta thy rng, c ln chm su xung 30 mt, th nhit trong lp trm tch tng t 0,54 1,200C, cn p sut tng t 3 7,5 atm. Nhng vy su cng ln, nhit , p sut cng tng v trong cc lp trm tch to du kh, nhit c th ln ti 100 2000C v p sut t 200 1000 at. iu kin ny, cc hydrocacbon c phn t ln, mch di, cu trc phc tp s phn hy nhit, to thnh cc cht c phn t nh hn, cu trc n gin hn, s lng vng thm t hnThi gian di cng l cc yu t thc y qu trnh crcking xy ra mnh hn. Chnh v vy, tui du cng cao, ln chm cng su, du c to thnh cng cha nhiu hydrocacbon vi trng lng phn t cng nh. Su hn na c kh nng chuyn ha hon ton thnh kh, trong kh metan l bn vng nht nn hm lng ca n rt cao. Cng chnh v vy, khi tng chiu su ca cc ging khoan thm d du kh th xc sut tm thy kh thng cao hn.

1.2. Thnh phn ha hc 1.2.1. Thnh phn hydrocacbon trong du m

Hydrocacbon l thnh phn chnh ca du, hu nh cc loi hydrocacbon (tr olefin) u c mt trong du m. Chng c chia thnh cc nhm parafin, naphten, aromat, hn hp naphten aromat.Hydrocacbon parafinic

Hydrocacbon parafinic (cn gi l alcan) l loi hydrocacbon ph bin nht. Trong du m chng tn ti ba dng: kh, lng, rn. Cc hydrocacbon kh (C1 C4), khi nm trong du, do p sut cao nn chng tn ti th lng v ha tan trong du m. Sau khi khai thc, do p sut gim, chng thot ra khi du. Cc kh ny gm metan, etan, propan v butan gi l kh ng hnh, ngoi ra cn c mt lng rt nh pentan bay hi ra cng.Trong du m c hai loi parafin: n parafin v izo parafin, trong n parafin chim a s (25 30% th tch) chng c s nguyn t t C1 n C45. Cc n parfin c s nguyn t cacbon bng hoc ln hn C18, nhit thng chng l cht rn. Cc parafin ny c th ha tan trong du hoc to thnh cc tinh th l lng trong du. Khi hm lng cc parafin ln qu cao, du c th b ng c, gy kh khn cho qu trnh vn chuyn. Hm lng ca chng cng cao, nhit ng c ca du cng ln. Khi bm v vn chuyn cc loi du ny phi p dng cc phng php sau: Gia nhit ng ng, cho thm ph gia, tch bt parafin rn ti ni khai thc h im ng c. Cc parafin rn tch t du th l nguyn liu qu tng hp ha hc, iu ch cht ty ra tng hp, t si nhn to, phn bn, cht doCc izo parafin thng ch nm phn nh v phn c nhit si trung bnh ca du. Chng thng c cu trc n gin, mch chnh di, nhnh ph t v ngn, nhnh ph thng l nhm metyl. Cc izo parafin c s cacbon t C5 n C10 l cc cu t rt qu, chng lm tng kh nng kh nng chng kch n (tng tr s octan) ca xng.Hydrocacbon naphtenic

Naphtenic (xyclo parafin) l mt trong s hydrocacbon ph bin v quan trng trong du m. Hm lng c th thay i t 30 n 60% trng lng. Chng thng dng vng 5, 6 cnh, cng c th dng ngng t 2 hoc 3 vng. Cc hydrocacbon naphtenic c mt trong cc phn on nh (thng l mt vng v t nhnh ph) hoc phn nhit trung bnh v cao (khi l cc cu t c nhiu vng v nhnh ph di).

Hydrocacbon naphtenic l thnh phn rt quan trng trong nhin liu ng c v du nhn. Cc naphtenic mt vng lm cho xng c cht lng cao; nhng hydrocacbon naphtenic mt vng c mch nhnh di l thnh phn rt tt cho du nhn v chng c nht cao v t thay i theo nhit . c bit, chng l cc cu t rt qu cho nhin liu phn lc, do chng c nhit chy cao, ng thi gi c tnh linh ng nhit thp.Hydrocacbon naphtenic trong du m cn l nguyn liu qu t iu ch cc hydrocacbon thm: benzen, toluen, xylen (BTX), l cc cht khi u trong sn xut t si tng hp v cht do.

Du m cha nhiu hydrocacbon naphtenic l nguyn liu tt cho sn sut du nhn c cht lng tt. Chng li c nhit ng c thp nn gi c tnh linh ng, khng gy kh khn cho qu trnh bm, vn chuyn, phun nhin liu. Hydrocacbon thm (aromat)

Hydrocacbon thm thng gp l loi mt vng v ng ng ca chng (benzen, toluen, xylen). Cc cht ny thng nm trong phn nh v l cu t lm tng kh nng chng kch n ca xng. Cc cht ngng t 2, 3 hoc 4 vng thm c mt trong phn c nhit si trung bnh v cao ca du m; hm lng cc cht ny thng t hn.

Khc vi nhin liu xng, nhin liu phn lc v diezen nu hm lng aromat nhiu th chng lm gim cht lng ca cc loi nhin liu do kh t bc chy v to cc, to cn trong ng c. Cc cu t aromat mt vng c nhnh ph di l nguyn liu qu sn xut du nhn c nht v ch s nht cao.Hydrocacbon loi hn hp naphten aromat

Loi ny rt ph bin trong du, chng thng nm phn on c nhit si cao. Mt s hydrocacbon hn hp naphten aromat thng gp trong du m c cu trc nh sau:

1.2.2. Cc thnh phn phi hydocacbon

Cc cht cha lu hunh

Trong thnh phn phi hydrocacbon cc hp cht lu hunh l ph bin nht, chng lm xu i cht lng ca du th. Cc loi du cha t hn 0,5% lu hunh l loi du tt, du cha t 2% lu hunh tr ln l loi du xu. Cc cht cha lu hunh thng dng sau: Mercaptan

Sunfua

Disunfua

Thiophen

Lu hunh t doR-S-HR-S-R

R-S-S-R

S, H2S

Lu hunh dng mercaptan: mercaptan l cc hp cht c nhm SH lin kt trc tip vi gc hydrocacbon, chng khng bn v d phn hy nhit cao:2RSH R-S-R + H2S

RSH R-CH=CH2 + H2S

Cc cht mercaptan thng c trong phn on nhit si thp, gc hydrocacbon thng t C1 C8.

Lu hunh dng sunfua v disunfua: cc cht ny thng c cc phn on c nhit si trung bnh v cao. Gc hydrocacbon c th l mch thng, vng no hoc vng thm. V d:

Lu hunh dng thiophen: cc hp cht cha lu hunh dng thiophen c cu trc mch vng, nh:

Thiophen l loi cht cha lu hunh ph bin nht (chim t 45 92% trong tt c cc dng hp cht cha lu hunh ca du m). Chng thng c phn nhit si trung bnh v cao ca du.

Lu hunh dng t do: l lu hunh dng nguyn t v dng H2S. Da vo hm lng lu hunh dng H2S c trong du m ngi ta phn thnh hai loi du: du chua lng H2S > 3,7 ml/ 1 lit du, du ngt lng H2S < 3,7 ml/ 1 lit du.Cc cht cha nit

Cc cht cha nit thng c rt t trong du m (0,01 n 1% trng lng), chng nm trong phn on c nhit si cao, thng c 1, 2 hoc 3 nguyn t Nit. Nhng hp cht c mt nguyn t nit thng c tnh baz v l loi chnh. Mt s v d v cc hp cht cha mt nit nh sau:

Cc cht cha oxy

Cc cht cha oxy trong du m thng tn ti di dng axit, xeton, phenol, ete, estetrong cc axit v phenol l quan trng hn c, chng thng nm nhit si trung bnh v cao. Cc phenol thng gp l:

Cc kim loi nng

Hm lng cc kim loi c trong du thng khng nhiu (vi phn triu). Chng c trong cu trc ca cc phc kim loi, ch yu l phc ca hai nguyn t V v Ni. Ngoi ra cn c mt lng rt nh cc nguyn t khc nh Fe, Cu, Zn, TiHm lng kim loi nng nhiu s nh hng n qu trnh ch bin xc tc, chng s lm ng c xc tc. V vy, i vi qu trnh crcking v reforming, yu cu hm lng ny khng c qu 5 n 10 ppm.

Cc cht nha v asphanten

Nha v asphanten l nhng cht cha ng thi cc nguyn t C, H, O, S, N; c phn t lng rt ln (500 600 vC tr ln). Nhn b ngoi chng u c mu sm, nng hn nc, v khng tan trong nc. Chng u c cu trc h vng thm ngng t cao, thng tp trung nhiu phn nng, nht l trong cn du m. Tuy nhin cng c th phn bit c nha v asphanten theo cc c im sau y:

Nha

Trng lng phn t: 600 1000 vC D tan trong dung mi hu c. Khi tan to dung dch thc thm ha: 0,140,25Asphanten

Trng lng phn t: 1000 2500 vC

Kh tan trong dung mi hu c. Khi tan to dung dch keo

thm ha: 0,20,7

Cc cht nha v asphanten thng c nhiu phn nng, c bit l phn cn sau khi chng ct, chng u lm xu i cht lng ca du m. S c mt ca chng trong nhin liu s lm cho sn phm b sm mu, khi chy khng ht s to cn, u c xc tc. Tuy nhin, du m no cha nhiu nha v asphanten s l ngun nguyn liu tt sn xut nha ngNc

Trong du m, bao gi cng c ln mt lng nc nht nh, chng tn ti dng nh tng. Cc nguyn nhn dn n s c mt ca nc trong du m, l: nc c t khi thnh nn du kh do s ln chm ca cc vt liu hu c di y bin v nc t kh quyn ngm vo cc m du.

Nc trong du m cha mt lng rt ln cc mui khong. Cc cation v anion thng gp l: Na+, Ca2+, Mg2+, HCO3-, SO42-Ngoi ra cn mt s oxit khng phn ly dng keo nh: Al2O3, Fe2O3, SiO2.Khi khai thc du, lng, nc s tch ra khi du. Trong trng hp nc to thnh h nh tng bn vng, lc mun tch nc phi dng ph gia ph nh.

Cn ch mt s mui khong trong nc b thy phn to ra axit, gy n mn thit b theo phn ng:

MgCl2 + 2H2O Mg(OH)2 + 2HCl

MgCl2 + 2H2O Mg(OH)Cl + HCl

CHNG 2

TNH CHT VT L C TRNG CA DU TH V PHN LOI DU M2.1. Xc nh cc c trng vt l ca phn on du m

2.1.1. Thnh phn chng ct phn on

Thnh phn ct l mt trong nhng ch tiu quan trng cn phi xc nh i vi cc sn phm trng nh xng, kerosen, izen. Theo thnh phn ct phn on c th bit c cc loi sn phm thu v khi lung ca chng. Cc phn on du bao gi cng gm rt nhiu cc n cht khc nhau vi nhit si thay i. Do vy c trng cho tnh cht bay hi ca mt s phn on l nhit si u v nhit si cui.

Qu trnh chng ct c thc hin trong b chng ct tiu chun Engler.

Cho 100 ml mu vo bnh. Gia nhit nhit t t, tc thng thng t 4 n 5 ml sn phm trong 1 pht. Khi c git lng u tin rt xung bnh hng th nhit si lc l nhit si u, tip ghi li nhit si ng vi 10, 20, 30, 90% th tch. n khi no ct thy ngn trong nhit k t cc i tt xung t ngt th l nhit si cui.

T cc gi tr , ta dng th ph thuc gia % sn phm chng ct c v nhit si gi l ng cong chng ct.

Mi mt loi nhin liu, c c trng bi thnh phn chng ct nht nh. Nhng nhn chung, nu cng l xng, hoc cng l kerosen th yu cu v khong nhit si gn nh nhau.

Thnh phn ct phn on xng ng c c ngha rt quan trng. Nhit si t 10 n 30% c ngha quyt nh kh nng khi ng ca ng c. Khong nhit cng thp ng c cng d khi ng khi my ngui. Tuy nhin thp qu, d to nt hi trong h thng cp nhin liu gy hao tn nhin liu. Nn nhit si 10% khng vut qu 700C.

Nhit ct 50% c ngha quyt nh kh nng tng tc ca ng c v qu trnh t nng ng c. Nu nhit ct 50% qu cao khi thay i tc , lng nhin liu trong my t, cng sut gim iu khin xe kh khn. Do vy nhit ct 50% (t 40% n 70%) cng thp cng tt v d dng tng s vng quay ca ng c ln mc ti a trong thi gian ngn nht. Tuy vy nu qu thp s to nt hi gy tht thot nhin liu (v vy khng nn vt qu 1400C).

Nhit ct 90% c ngha v mt kinh t, nu nhit 90% cao, xng khng bc hi hon ton trong bung t. Xng trng thi lng theo xylanh vt qua xecmng vo cate cha du, lm long du nhn, lm gim kh nng bi trn v mi mn ng c.

Nhit ct cui nh gi mc bay hi hon ton v lm long du nhn. Nu nhit si cui cao qu tr du nhn s b ra tri trn thnh xylanh, mi mn piston, v th nhit si cui khng qu c 2050C.

2.1.2. p sut hi bo ha

p sut hi bo ha l mt trong cc tnh cht vt l quan trng ca cc cht lng d bay hi. y chnh l p sut hi m ti , th hi cn bng vi th lng. Cht lng c p sut hi bo ha cng ln th iu kin bo qun, tn tr v vn chuyn cng phi nghim ngt, tun th cht ch cc bin php an ton phng chng chy n.

p sut hi bo ha Reid l p sut tuyt i 1000F (37,80C) c trng c trng cho kh nng bay hi ca phn on xng. l p sut hi bo ha o c iu kin ca bom Reid 37,80C. i lng ny cng ln bay hi cng cao.

p sut hi bo ha c xc nh trong dng c tiu chun gi l bm Reid (hnh 5.1).

Cho xng vo bnh 2, ni thng vi bnh 1, ri cho vo bnh n nhit, sau khi n nh nhit (37,80C) trong 15 pht th m vn ni ton b h thng vi p k thy ngn. chnh lch h s cho bit p sut hi bo ha ca xng cn o. bc hi ca xng cng cao, chnh h cng ln.

2.1.3. T trng

T trng l t s gia trng lng ring ca mt vt mt nhit nht nh v trng lng ring ca mt vt khc c chn l chun, xc nh cng v tr. i vi cc loi sn phm du lng u ly nc ct nhit 40C v p sut 760 mmHg lm chun.

T trng ca du m, hoc mt phn on du m nhit t trn trng lng ring ca nc 40C, ta c th ghi dt4. d so snh, t trng c biu th cng mt nhit , phn ln cc nc u ly 200C (d204) hoc 15,60C (tng ng vi 600F) so vi nc cng nhit .

mt s nc in hnh l M cn biu th t trng bng 0API. Cng thc chuyn i t trng sang 0API nh sau:

T trng ca sn phm du m thay i rt nhiu khi nhit thay i, nhng khng ph thuc vo p sut. Tuy nhin nu p sut cao th c nh hng cht t.

C th xc nh t trng bng phng php nh: dng ph k, cn thy tnh, picnomet. Phng php picnomet l ph bin nht, dng cho bt k loi cht lng no. Phng php ny da trn s so snh trng lng ca du vi nc ct trong cng th tch v cng nhit .

2.1.4. nht

nht l tnh cht ca mt cht lng, c xem l ma st ni ca cht lng v cn tr s chy ca cht lng. nguyn nhn c nht l do i lc c hc gia cc ht cu to nn cht lng.

nht ca du m c lin quan nqu trnh bm vn chuyn, s bi trn, s phun nhin liu trong cc ng c. nht ph thuc vo nhit , khi nhit tng nht gim.

nht ng lc (hoc ): nht ng lc biu th cho cc cht lng dng khng c gia tc, c tnh bng cng thc:

= C

Trong : l thi gian chy ca cht lng

C l hng s nht k, khng ph thuc vo nhit m ch ph thuc vo kch thc hnh hc ca nht k.

Nu nht ln phi dng nht k c ng knh mao qun ln; cn nht ca cht lng cn o nh, th dng nht k c ng knh mao qun nh; sao cho thi gian chy ca cht lng khng qu 200 giy.

nht ng lc c tnh bng poaz (P) hay centipoaz (cP).

1 P = 100 cP = 0,1 N.s/ m2 = 1 dyn.s/ cm2 = 1 g/cm.s

nht ng hc ():ng nht ng hc l t s gia nht ng lc hc v t trng n (c hai u xc nh cng nhit v p sut):

Trong : l nht ng hc, tnh bng stc (St) hoc centistc (cSt)

l nht ng lc

d l trng lng ring, g/cm31 St = 1 cm2/s = 100 cSt

Xc nh nht ng hc bng cch o thi gian chy ca du qua nht k mao qun Pinkvic.

nht quy c ( nht Engler): nht quy c hay nht biu kin, cn gi l nht Engler l t s gia thi gian chy ca 200 ml mu nhit th nghim v 200 ml nc ct 200C qua ng nh trong dng c o nht:

Trong :

l nht Engler nhit t.

t l thi gian chy ca mu nhit t

0 l thi gian chy ca nc 200C

2.1.5. ng cong im si thc

xc nh thnh phn phn on ca du m, thng tin hnh chng ct trong b chng ct tiu chun vi cc iu kin quy nh cht ch, gi l chng phc tp (va chng va luyn).

Qu trnh chng ct nhng vy s cho phn chia cao. Sau dng th quan h nhit si - phn trm sn phm chng ct so vi du th (% th tch hoc trng lng). th ny gi l ng cong im si thc.

T kt qu thu c xc nh im si thc, c th xc nh thnh phn cc phn on ca du m c nhit si n 2000C, 3000C n 4850C (hnh 2.2).

Ni chung, ng cong im si thc l mt ng cong quan trng nht ca du m. N cho php nh gi c thnh phn ca cc phn on c nhit si khc nhau. Ngoi ra cn gip cc nh cng ngh xc nh phng n ch bin t yu cu v cht lng v s lng cc phn on mong mun.

2.1.6. im anilin

im anilin l nhit thp nht trong iu kin xc nh, anilin l sn phm tng ng ha tan vo nhau to thnh mt hn hp ng nht. Khi thnh phn ha hc khc nhau th gi tr ca im anilin khc nhau. Hydrocacbon thm c im anilin thp hn so vi cc loi hydrocacbon khc rt nhiu (v hydrocacbon d dng tan trong anilin hn). Trong cng mt loi hydrocacbon th im anilin tng ln theo trng lng phn t.

im anilin thng thng c xc nh qua phng php th tch bng nhau gia anilin v sn phm. Anilin dng xc nh phi khng c mu, va mi chng ct. Ch dng phn chng ct trong khong 10 n 90%.

Phng php im anilin thng c s dng xc nh thnh phn cc hydrocacbon thm c trong phn on. hm lng hydrocacbon thm cng ln, im anilin cng thp.

2.1.7. Nhit chp chy

Nhit chp chy l nhit ti , khi phn on du m c t nng, hi hydrocacbon s thot ra to vi khng kh xung quanh mt hn hp m nu a ngn la n gn chng s bng chy ri pht tt nh l mt tia chp.

Nh vy nhit chp chy lin quan n hm lng cc sn phm nh trong phn on. Du cng c nhiu cu t nh, nhit chp chy cng thp.

Phn on xng: Nhit chp chy khng quy nh, thng l m.

Phn on kerosen: Nhit chp chy t 28 n 600C, thng thng 400C.

Nhit izen: Nhit chp chy cc kn t 35 n 860C, thng thng l 600C.

Phn on du nhn: Nhit chp chy t 130 n 2400C.

C hai phng php xc nh nhit chp chy: Phng php cc kn v phng php cc h.

Phng php cc kn thng p dng i vi i vi cc sn phm d bay hi nh kerosen, k c diesen.

Phng php cc h thng p dng i vi cc sn phm khng bay hi nh du nhn.

Phng php cc kn bao gi cng cho nhit chp chy thp hn so vi phng php cc h.

Xc nh nhit chp chy c ngha rt quan trng trong vic tn cha v bo qun nhin liu. Nu nhit chp chy ca nhin liu thp, khi bo qun trong b cha ngoi tri nng nng phi phng c tia la in gn trnh chy n. i vi nhin liu izen cho xe tng, nu nhit chp chy thp, c ngha l hm lng cc cu t nh nhiu, rt nguy him cho ngi ngi trong v xe tng phi lm vic trong iu kin kn hon ton.

Khi xc nh nhit chp chy ca mt phn on no , thy nhit chp chy khc thng, c th ngh rng trong phn on ln cc nhin liu nh.

2.1.8. Nhit ng c, im ng c v im kt tinh

ng c l mt tnh cht ca du m v sn phm du m. Chng b mt tnh linh ng khi nhit h thp. Tnh linh ng mt i l do s to thnh nhng mng kt tinh parafin hoc do nht tng mnh.

Mng tinh th parafin to thnh v trong nhng sn phm du m gm hn hp hydrocacbon c nhit ng c khc nhau. Khi lm lnh n mt nhit nht nh, nhng parafin c phn t lng ln kt tinh trc, nhng hydrocacbon c phn t lng nh hn s chui vo khung ting th , dn n s vn c trc khi ng c. Thng thng im vn c ln hn im ng c t 3 n 50C.

S ph thuc nhit ng c vo hm lng parafin c biu din qua biu thc sau:

Trong

C l hm lng parafin rn c trong phn on (% trng lng)

K1, K2 l cc hng s

Trong trng hp hm lng parafin thp, s ng c l do khi gim nhit , nht tng mnh lm cho c khi nhin liu ng c li.

Nhng tnh trn ph thuc rt nhiu yu t nh: t l, cu to cc hydrocacbon trong sn phm du m, kiu lm lnh, nht, lng cc cht nha v asphanten, hm lng nc

im ng c: l nhit cao nht m sn phm du lng em lm lnh trong iu kin nht nh khng cn chy c na.

im vn c: l nhit m khi sn phm em lm lnh trong nhng iu kin nht nh, n bt u vn c do mt s cu t bt u kt tinh.

im kt tinh: l nhit sn phm bt u kt tinh c th nhn thy bng mt thng.

2.1.9. Nhit chy

Nhit chy l lng nhit ta ra khi t chy mt lng nhin liu vi iu kin l nhit ca nhin liu trc khi t v sn phm chy l 200C. Nhit chy l mt trong nhng c tnh ch yu ca nhin liu. Khi t chy hon ton cc nhin liu kh, nhin liu lng hoc nhin liu rn u to thnh CO2 v H2O v ta nhit theo phn ng:

Trong trng hp nhin liu cha lu hunh s to thnh SO2

Nc to thnh c th th lng hoc th hi.

Gi tr nhit lng cao (Qcao) l lng nhit ta ra khi tt c nc trong sn phm chy trng thi lng, Qcao = Q1 + Q2:

H2Ohi H2Olng + Q2

Gi tr nhit lng thp (Qthp) l lng nhit ta ra khi tt c nc trong sn phm chy trng thi kh.

Hiu gia nhit lng trn v nhit lng di chnh l nhit lng cn thit nc chuyn t trng thi lng sang trng thi hi, nhit lng ny gi l nhit ha hi ca nc.

2.1.10. Hm lng nc trong phn on du m

Nhn chung nc khng ha tan trong du m v cc phn on ca du m. Nhng khi tng nhit th ha tan ca nc trong du m s tng ln.

S c mt ca nc trong mt s phn on du gy nguy him cho qu trnh s dng, chng hn:

Nu trong du bin th c nc s lm gim cch in.

Trong nhin liu phn lc c nc s gy nguy him, v my bay lm vic cao ln, nhit h rt thp (khong 500C), lng nc c trong nhin liu s to thnh cc tinh th nc l tc vi phun, gy gin on cung cp nhin liu.

Trong sn sut LPG, khi dn n s h nhit , nc s to thnh cc tinh th nh gy tc van gim p.

Do vy cn phi tch nc ra khi cc phn on sao cho hm lng nc cng nh cng tt.

2.1.11. Tr s octan

Tr s octan l i lng c trng cho kh nng chng kch n ca nhin liu. C hai phng php xc nh tr s octan, l phng php nghin cu (RON) v phng php mt (MON).

Bn cht ca phng php ny l so snh bn chng kch n ca nhin liu th nghim v nhin liu tiu chun, biu th bng tr s octan. bn chng kch n ca izo-octan qui c bng 100 v ca n-heptan bng 0.

2.2. nh gi cht lng ca du m qua cc c trng sau

xc nh gi tr ca du th trn th trng, ng thi nh hng cho cc qu trnh s dng, ch bin, tnh ton cng sut thit b cho nh my lc du, vic phn tch, xc nh cc ch tiu ca du th l rt cn thit. C rt nhiu c tnh quan trng, trong phn ny ch a ra cc tnh cht tiu biu nht, lin quan n s dng v qu trnh cng ngh ch bin chng.

2.2.1. Thnh phn hydrocacbon trong du m

Hydrocacbon l thnh phn quan trng nht ca du th, trong du chng chim t 60 n 90% trng lng. Du cha cng nhiu hydrocacbon th cng c gi tr kinh t cao. Ph thuc vo hm lng ca tng loi: pararfin, naphten, aromat m c th sn xut c cc sn phm nhin liu c cht lng khc nhau. Du cha naphten, aromat s cho php sn xut xng c tr s octan cao. Du cha nhiu n-parafin s l ngun to ra nhin liu izen c cht lng tt, nhng hm lng parafin rn cao qu s lm tng im ng c ca du, gy kh khn cho qu trnh vn chuyn, bc rt, phi p dng cc bin php h im ng, gy tn km. Du trung gian naphten - parafinic s l nguyn liu tt sn xut ra du nhn c ch s nht cao.

Khi khai thc c du th, nht thit phi xc nh hm lng v c tnh ca cc hydrocacbon c trong du. C nhiu phng php xc nh chng nhng ph bin l phng php ha l nh sc k kh, ph hng ngoi (IR) v t ngoi (UV).

2.2.2. T trng

Da vo t trng c th s b nh gi du m thuc loi nng hay nh, mc bin cht thp hay cao. Theo t trng, ph bin ngi ta chia du thay 3 cp:

Du nh:

Du trung bnh:

Du nng:

Du th cng nh, hiu sut v cht lng cc sn phm trng thu c khi chng ct cng cao; du cng cha t lu hunh, cng mang nhiu c tnh parafinic hoc trung gian naphtenic parafinic. Du cng nng th cha cng nhiu cc cht d nguyn t, cc cht nha v asphanten, khng thun li sn xut cc sn phm nhin liu v du nhn, nhng li l nguyn liu tt sn xut bitum nha ng v cc.

2.2.3. H s c trng K

H s ny cho bit du m mang c tnh ca loi hydrocacbon no l ch yu. H s K dao ng trong khong t 10 n 13, trong :

H du parafinic

H du naphtenic

H du aromaticK = 13 12,5

K = 11,45 10,5

K = 10

Cc h du trung gian c gi tr K nm gia cc s trn. Bit c h du th l h g s c hng s dng hp l. Chng hn mt loi du th c K = 12, du s thuc loi trung gian naphteno parafinic, n cho hiu sut v cht lng ca xng, kerosen, gasoil cao, bitum thu c t cn du s khng tt.

2.2.4. Hm lng cc hp cht cha cc nguyn t d th

Cc cht cha lu hunh

Lu hunh l hp cht ch yu c trong du th. Chng tn ti nhiu dng: mercaptan, sunfua, disunfua, H2S, S. Cn c vo hm lng lu hunh ngi ta chia du m lm ba loi: Du m t lu hunh

Du m c lu hunh

Du m nhiu lu hunhS < 0,5%

S = 0,512%

S > 2%

Du m cha nhiu lu hunh c gi tr kinh t thp hn du m t lu hunh. Lu hunh l cht gy nhiu tc hi: Khi t chy to ra SO2, SO3 gy c hi v n mn ng ng, thit b. Mt khc, khi a du th i ch bin ha hc, lu hunh s l nguyn nhn gy ng c xc tc, lm gim hiu sut v cht lng sn phm. Thng thng du cng nng th hm lng lu hunh cng cao.

Hm lng Nit trong du

Cc cht cha nit trong du thng t hn so vi lu hunh. Chng thng c tnh baz nn c nh hng ln n qu trnh ch bin du trn xc tc axit (qu trnh crcking, reforming, alkyl ha), n l nguyn nhn gy nn mt hot tnh xc tc, to cn trong ng c v lm bin mu sn phm.

Cc cht nha v asphanten.

Du m c nhiu nha v asphanten th trong sn phm (du nhn v cn) cng c nhiu cht . Ni chung nha v asphanten l nhng cht c hi. Nu trong sn phm c nha v asphanten th kh nng chy s khng hon ton, to cn v tn, lm tc vi phun ca ng c. Nha l cht d b oxi ha, s lm gim tnh n ng ca sn phm. Tuy nhin du th cha nhiu nha v asphanten th phn cn li l nguyn liu tt sn xut bitum. Phn cn grudron ca du th Vit Nam c tng hm lng nha v asphanten l rt thp nn khng th s dng sn xut bitum.

2.2.5. nht

Da vo nht ca du m c th tnh ton c cc qu trnh bm vn chuyn. Du c nht cng cao th cng kh vn chuyn bng ng ng. vn chuyn phi tiu hao nng lng, v vy chi ch vn chuyn s tng ln. i vi du th cng nng th nht cng cao. i vi cc phn on du m, chng hn du nhn nht gn nh l mt ch tiu quan trng nht nhm m bo cho qu trnh bi trn tt.

2.2.6. Nhit ng c

Nhit ng c phn nh tnh linh ng ca du nhit thp. Nu nhit ng c ca mt loi du no cao th s rt kh khn cho qu trnh vn chuyn, bm rt, phi tin hnh cc bin php lm gim nhit ng c nh gia nhit gy tn km.

C hai nguyn nhn dn n du c nhit ng c cao, l: du c nht ln v du cha nhiu n parafin rn. V d du th Bch H cha nhiu n parafin rn nn nhit ng c l +330C.

2.2.7. Nhit chp chy

Nhit chp chy phn nh hm lng cc hydrocacbon nh c trong du v cho bit nguy him i vi hin tng chy n khi bo qun v vn chuyn. Nhit chp chy cng thp, cng gn vi nhit ca mi trng th cn phi thn trng khi bo qun v vn chuyn. Phi c cc bin php phng gim ti a cc hin tng chy n.

V d, xng c nhit chp chy thp nn bo qun an ton cho cc bn b cha xng, ngi ta thng sn nh trng phn x nhit, h thng ti nc lm mt b, hoc xy b ngm.

2.2.8. Hm lng cc conradson

cc ha conradson l i lng c trng cho kh nng to cc ca phn cn du m. i lng ny cng cao th hiu sut cc thu c cng cao. Hm lng cc conradson cng cao cn c ngha hm lng nha v asphanten trong du m s cao, v c th s dng cn du m loi ny sn xut bitum nha ng vi hiu sut v cht lng tt.

2.2.9. Kim loi nng trong du

Trong du m thng c nhiu kim loi mc vi lng nh V, Ni, Co, Pb, Ti, Mntrong ch yu l hai nguyn t Vanadi v Niken. Hm lng cc kim loi trong du phn nh mc nh hng ca chng khi s dng cc phn on lm nhin liu v nguyn liu cho cc qu trnh ch bin. V d, nu trong nhin liu t l c nhiu V, Ni cc kim loi ny s gy thng l do to thnh cc hp kim vi st c nhit nng chy thp, cn trong phn ng reforming xc tc, cc kim loi Pb, As s lm xc tc mt hot tnh (ng c xc tc).

i vi du th Vit Nam, hm lng trung bnh ca V v Ni rt thp, hm lng Vanadi trong phn cn cng ch khong 0,46 ppm, cn Ni l 10,503 ppm.

2.3. Cc c tnh ca du th v sn phm du m

2.3.1. Tnh bay hi

Tnh bay hi c trng cho kh nng chuyn t dng lng sang dng hi ca mt sn phm.

Ty thuc vo nhit , p sut mt cht c th tn ti dng ny hay dng khc, hay cc dng nm cn bng vi nhau. i vi cc nguyn cht, p sut xc nh s ha hi xy ra nhit khng i. Khi p sut tng th nhit ha hi tng. p sut do pha hi gy ra nm cn bng vi pha lng nhit xc nh gi l p sut hi.

i vi cu t nh d bay hi th p sut hi cng cao v nhit si cng thp. Ngc li cu t cng nng cng kh bay hi th p sut hi cng thp v nhit si cng cao.

Nhng i vi cc sn phm du kh c c trng bi khong nhit si. V d phn on xng, khong nhit si t 300C n 1800C.

Trong qu trnh s dng cc sn phm nng lng phi chuyn t dng lng khi tn tr sang dng hi khi s dng. V vy n i hi phi c giai on ha hi, i vi cc sn phm du kh, s ha hi xy ra nhit tng dn trong qu trnh ha hi. Mt khc, mt c im rt quan trng c lin quan n qu trnh ha hi l s ha hi tiu th nng lng. Ngc li qu trnh ngng t l qu trnh ta nhit. y l cc c tnh cn phi ch khi s dng cc sn phm du kh, v n dn n vn nh: lm h nhit mi trng, kh khi ng ng c iu kin lnh

2.3.2. Tnh bt chy

Chy l qu trnh oxi ha mt cht din ra rt nhanh v km theo ta nhiu nhit, y l qu trnh phc tp, trong phn ng oxy ha l c s ca qu trnh t chy cc sn phm du kh bng oxi (khng kh) th s to thnh cc sn phm chy CO2, H2O, SO2Nhit tr ca cc cht c th tham kho bng 3.1

(C, H, S) + O2 CO2 + H2O + SO2 + Q

Cc sn phm du kh c nhit tr cao, t l H/C cng cao v hm lng lu hunh cng thp th nhit tr cng cao. Nhng qu trnh chy xy ra hon ton nht thit phi hi t cc iu kin sau:

Cn thit phi a sn phm sang dng hi.

S dng lng thch hp khng kh v sn phm: qu trnh chy xy ra th t l nhin liu v khng kh phi nm trong khong gia gii hn chy di v gii hn chy trn.

Cn c nng lng khi mo: tia la in ca buri, ngn la mi hoc nhit cao.

Bng 3.1. Nhit chy ca mt s cht

Cht tSn phm chyNhit tr (kcal/ kg)

CKh CO28133

HHi H2O29100

SKh SO22322

2.3.3. Tnh lu chuyn

S lu chuyn ca cc sn phm du kh thng qua hai thng s: t trng v nht, l hai thng s thay i theo nhit , khi nhit tng t trng v nht gim, nh hng ny l ng k.

2.3.4. T trng

T trng l t s gia trng lng ring ca mt vt mt nhit nht nh v trng lng ring ca mt vt khc c chn l chun, xc nh cng v tr. i vi cc loi sn phm du lng u ly nc ct nhit 40C v p sut 760 mmHg lm chun.

T trng ca du m, hoc mt phn on du m nhit t trn trng lng ring ca nc 40C, ta c th ghi dt4, v trong h CGS biu th bng g/cm3. d so snh, t trng c biu th cng mt nhit , phn ln cc nc u ly 200C (d204) hoc 15,60C (tng ng vi 600F) so vi nc cng nhit .

mt s nc cn biu th t trng bng 0API. Cng thc chuyn i t trng sang 0API nh sau:

T trng ca sn phm du m thay i rt nhiu khi nhit thay i, nhng khng ph thuc vo p sut. Tuy nhin nu p sut cao th c nh hng cht t.

2.3.5. nht

nht l tnh cht ca mt cht lng, c xem l ma st ni ca cht lng v cn tr s chy ca cht lng. Nguyn nhn c nht l do i lc c hc gia cc ht cu to nn cht lng.

nht ca du m c lin quan n qu trnh bm vn chuyn, s bi trn, s phun nhin liu trong cc ng c. nht ph thuc vo nhit , khi nhit tng nht gim.

nht ng lc (hoc ): nht ng lc biu th cho cc cht lng dng khng c gia tc, c tnh bng cng thc:

= C

Trong : l thi gian chy ca cht lng

C l hng s nht k, khng ph thuc vo nhit m ch ph thuc vo kch thc hnh hc ca nht k.

Nu nht ln phi dng nht k c ng knh mao qun ln; cn nht ca cht lng cn o nh, th dng nht k c ng knh mao qun nh; sao cho thi gian chy ca cht lng khng qu 200 giy.

nht ng lc c tnh bng poaz (P) hay centipoaz (cP).

1 P = 100 cP = 0,1 N.s/ m2 = 1 dyn.s/ cm2 = 1 g/cm.s

nht ng hc (): nht ng hc l t s gia nht ng lc hc v khi lng ring ca n (c hai u xc nh cng nhit v p sut):

Trong : l nht ng hc, tnh bng stc (St) hoc centistc (cSt)

l nht ng lc

d l khi lng ring, g/cm3

1 St = 1 cm2/s = 100 cSt

Cc sn phm du kh c nht cng cao th tnh lu ng cng thp. nht cn nh hng n kh nng bm, kh nng phun sng v kh nng bi trn.

2.3.6. Tnh lu chuyn trong iu kin lnh

Khi nhit ca sn phm du kh gim, nht tng dn n tnh lu chuyn gim. Nu tip tc gim nhit , bt u xut hin cc vi tinh th rn, cc tinh th ny to dn n mt lc no lu cht s c li v ng khi lm cn tr qu trnh lu chuyn. Kh nng kt tinh ph thuc vo cc hydrocacbon c mt trong sn phm v c xp theo th t tng dn nh sau:

Aromatic < Naphtenic < iso-parafinic < n-parafinic

Nh vy kh nng kt tinh ch yu l do n-parafinic v tng dn khi s nguyn t cacbon tng. V d nhit kt tinh ca mt s n-parafinic c cho trong bng 3.2.

Bng 3.2. Nhit kt tinh ca n-parafinic

n-parafinicn-C4H10n-C8H18n-C16H34n-C26H54n-C44H90

T0kt (0C) -138-57+18+56+86

2.3.7. Tnh n mn v s c hi ca cc sn phm du m

Khi t chy cc sn phm du kh s sinh ra mt lng ln kh thi gm: CO2, CO, SO2, NOx v mui than gy nhim bu kh quyn, c hi i vi con ngi v thc vt.

Ngoi ra trong khi thi cn c mt lng ch gy nh hng n sc khe cng ng. Cc hp cht ch hu c i vo c th ngi qua phi v rut thm ch c th hp th qua da. nh hng c hi ca ch hu ht l i vi h thn kinh. Cc triu chng nhim c r rng l mt ng, c nhng gic m kinh hong, mt tp trung, km n, bun nn, ri lon cm xc

Cc hp cht SOx sinh ra trong khi thi khi gp hi nc trong khng kh to thnh axit gy n mn ng c.

SO2 + 1/2O2 SO3

SO3 + H2O H2SO4

Ngoi ra trong cc sn phm du kh c th cha cc hp cht axt m chng c mt nh cc ph gia hoc cc sn phm bin cht to thnh trong qu trnh tn tr, cc hp cht lu hunh m ch yu l cc hp cht mercaptan (RSH), cc hp cht oxi, cc axit hu c (RCOOH). S c mt ca chng s gy nn qu trnh n mn ng ng v cc thit b tn tr.

2.4.Phn loi du m 2.4.1.Da vo bn cht ha hc

Phn loi theo bn cht ha hc c ngha l da vo thnh phn cc loi hydrocacbon c trong du. Nu trong du, h hydrocacbon no chim phn ch yu th du m s mang tn loi . V d, du parafinic th hm lng hydrocacbon parafinic trong phi chim 75% tr ln. Tuy nhin trong thc t, khng c bt k m du no li c thun chng mt loi hydrocacbon nh vy, nh vy thng ch c du trung gian; v d, mt loi du no c: hn 50% parafinic, ln hn 25% naphtenic v cn li l cc loi khc th c gi l du napteno - parafinic

C nhiu phng php khc nhau phn loi theo bn cht ha hc:

Phn loi theo Nelson, Waston v Murphy: theo cc tc gi ny, du m c c trng bi cc h s K, l mt hng s vt l quan trng, c trng cho bn cht ha hc ca du m, c tnh theo cng thc:

T: nhit si trung bnh ca du th, tnh bng Reomuya (0R), 10R = 1,250C.

d: t trng ca du th, xc nh 15,60C (600F) so vi mc cng nhit .

Gii hn h s K c trng phn chia du m nh sau:

Bng 2.1. H s K c trng ca cc h du m khc nhau

Du m h parafinic

Du m h trung gian

Du m h naphtenic

Du m h aromatic K = 13 12,15

K = 12,10 11,5

K = 11,45 10,5

K = 10

2.4.2.Phn loi du m theo bn cht vt l

Cch phn loi ny da theo t trng, bit t trng c th chia du th theo ba cp.

1. Du nh:

2. Du trung bnh:

3. Du nng:

Hoc c th phn du theo 5 cp sau:

4. Du rt nh:

5. Du nh va

6. Du hi nng:

7. Du nng:

8. Du rt nng

Ngoi ra trn th trng th gii cn s dng 0API thay cho t trng v 0API c tnh nh sau:

Du m c 0API cng nh th du cng nng.2.5.Thnh phn v phn loi kh 2.5.1.Phn loi

Kh hydrocacbon trong t nhin c phn loi theo ngun gc nh di y:

Kh thin nhin: L cc kh cha trong cc m kh ring bit. Trong kh ny thnh phn ch yu l metan (chim t 70 99%) cn li cc kh khc nh etan, propan v rt t butan.Kh ng hnh: l kh nm ln trong du m, c hnh thnh cng vi du, thnh phn ch yu l cc kh propan, butan, pentan

Kh ngng t (Condensate): Thc cht l dng trung gian gia du v kh (phn cui ca kh v phn u ca du), bao gm cc hydrocacbon nh propan, butan v mt s hydrocacbon lng khc nh pentan, hexan, thm ch hydrocacbon naphtenic v aromatic n gin. iu kin thng, kh ngng t dng lng. Kh ngng t l nguyn liu qu sn xut LPG v s dng trong tng hp ha du.

2.5.2.Thnh phn

c trng ch yu ca kh thin nhin v kh du m bao gm hai phn: phn hydrocacbon v phi hydrocacbon.

Cc hp cht hydrocacbon: Ch yu l cc kh metan v ng ng ca n nh: etan, propan, n butan, izo butan, ngoi ra cn mt t cc hp cht C5, C6. Hm lng cc cu t trn thay i ty theo ngun gc ca kh. V d, trong kh thin nhin cha ch yu l metan, cc kh nng C3 n C4 rt t; cn trong kh ng hnh, hm lng cc kh C3, C4 cao hn.Cc hp cht phi hydrocacbon: Ngoi thnh phn chnh l hydrocacbon, trong kh thin nhin v kh du m cn cha cc hp cht khc nh: CO2, N2, H2S, H2, He, Ar, NeTrong cc loi kh k trn, thng kh N2 chim phn ln. c bit, c nhng m kh cha He vi hm lng kh cao nh cc m kh t nhin M.Ngi ta c th s dng cc m kh lm ngun nguyn liu sn xut cc kh tr, thu hi H2S phc v cho cng nghip.

CHNG 3 CC PHN ON DU M V NG DNG CA CC PHN ON DU MGii thiu:Du m mun s dng c th phi tin hnh phn chia thnh tng phn on nh. Qu trnh phn chia da vo phng php chng ct thu c cc khong nhit si khc nhau. u tin, khi khai thc do c s gim p sut nn phn on kh b tch ra, thng t C1 n C4 v mt lng rt t C5, C6. Sau , ty thuc vo gii hn nhit si m ta thu c cc phn on sau:

Phn on xng: nhit si nh hn 1800C, bao gm cc thnh phn t C5 - C11.

Phn on kerosen: nhit si t 180 n 2500C, cha cc hydrocacbon t C11 - C16.

Phn on gasoil nh (cn gi l phn on diesel): nhit si t 250 - 3500C cha cc thnh phn t C16 - C21.

Phn on gasoil nng (cn gi l phn on du nhn), nhit si t 350 n 5000C, bao gm C21 n C25, thm ch n C40. Phn on cn gudron nhit si trn 5000C, gm cc thnh phn c s nguyn t cacbon t C41 tr ln, gii hn cui cng c th n C80.

Cc phn on k trn c ng dng trong nhiu mc ch khc nhau, nhng ch yu c s dng lm nhin liu hoc to cc sn phm ha hc. c th s dng vi hiu qu cao nht cc sn phm du m, cn phi nm vng cc c im, tnh cht ca tng phn on.

3.1. Phn on khPhn on kh bao gm cc hydrocacbon C1 n C4, mt lng rt t C5, C6. Cc kh ny c th khai thc t m kh hoc tch ra khi khoan du. Kh c ng dng lm nguyn liu cho cng nghip tng hp ha du v lm nhin liu t.3.1.1. Kh lm nguyn liu tng hp ha du

Tng hp amoniac

Amoniac (NH3) l nguyn liu ban u tng hp phn m. Qu trnh tng hp s dng ch yu l kh thin nhin qua cc qu trnh sau:u tin chuyn ha thnh kh tng hp (qu trnh reforming hi nc)

CH4 + O2 CO + 2H2CH4 + H2O CO + 3H2CO + H2O CO2 + H2Sau khi loi b CO l tip n giai on tng hp amoniac:

N2 + 3H2 2NH3 + QXc tc cho phn ng ny l cc oxyt nh Fe2O3, Fe3O4, FeO, Al2O3, Cr2O3, TiO2Phn ng ny xy ra p sut cao (25 n 100MPa), nhit 5000C.

Tng hp metanol

Metanol l mt trong nhng nguyn liu v dung mi quan trng trong cng nghip ha hc. Metanol cn c coi l nhin liu l tng v n c kh nng chy hon ton khng gy nhim mi trng, ngoi ra n c s dng lm ph gia tng tr s octan cho xng.

C th tng hp metanol bng cch oxy ha khng hon ton metan theo phn ng sau:CH4 + [O] CH3OHXc tc s dng trong qu trnh ny c th l: Cc kim loi Fe, Ni, Cu, Pd cc oxyt ca chng, hoc hn hp oxyt v kim loi.

Ngy nay trong cng nghip, xc tc c s dng l V2O5 vi nguyn liu l h CH4, O2, NO v cc nhit khc l nhit , p sut.

Trong cng nghip ha cht, mtanol c s dng nh l mt bn sn phm cho nhiu qu trnh tng hp cng nghip. Phn ln metanol dng cho iu ch formandehit v mt s cht quan trng nh: Cloruametyl (CH3Cl), metyl amin (CH3NH2), axit acetic (CH3COOH), vinylmetyl ete (CH3O-CH=CH2), metyl mercaptan (CH3SH)Nh vy, oxy ha trc tip metan c th thu c sn phm l metanol v formaldehyt. Vic s dng NOx nh l cht khi mo hoc cht oxi ha cho phn ng em li nhng hiu qu r rt. Thnh phn sn phm thu c khi oxy ha trc tip metan c th tham kho hnh 4.1.

3.1.2. Kh lm nhin liu t

Hin nay trong cng nghip s dng cc loi l t vi nhiu loi nhin liu truyn thng khc nhau nh D.O, F.O, than, in Phc v cho cng on gia nhit ca cc cng ngh sn xut khc nhau nh: nung, sy, hp. Lng nhin liu s dng trong lnh lc ny rt ln, do vy vic chuyn i nhin liu cng c ngha to ln.Chuyn ha kh thnh nhin liu t l hng s dng quan trng v c hiu qu cao, do cng ngh ha lng kh v ang pht trin trn phm vi ton cu.

Kh t nhin ha lng (LNG)

ngha quan trng nht ca vic ha lng kh t nhin l gim c 600 ln th tch, lm cho cng vic tn tr, vn chuyn v bo qun tr nn thun li hn rt nhiu.

Trong qu trnh ha lng kh t nhin, cc kh c nhit si thp s c lm lnh xung di im sng ca n. Kh t nhin ha lng c s dng lm nhin liu trong nhiu ngnh kinh t quc dn nh nng lng, cng nghip, giao thng vn ti, kh t dn dng, v t ra c u th hn hn so vi cc loi nhin liu khc. Chng hn nh trong ngnh nng lng, s dng kh t nhin sn xut in s lm gim gi thnh t 30 n 40%. Xy dng nh my chy bng kh t, vn u t s gim 20% so vi nh my chy bng than. Ngy nay, khong 20% tng lng kh tiu th trn th gii l phc v cho vic sn xut ra nng lng v d tnh con s ny trn th trng s tng mnh trong nhng nm ti. Nhiu nh my chu trnh hn hp kh ln ang c xy dng, v tng nhanh trong khi nhiu nh my nng lng sn c ang c trang b li tng hiu qu v gim cht thi NOx v SOx. Mt s h thng tm c ln cung cp hi qu trnh cng c s dng, gi l nhit nng lng kt hp (Combined heat and power CHP).Hin trn th gii vic s dng kh cho pht in l rt ph bin. cc nc c ngun kh thin nhin di do, kh c s dng cho my pht in chim t l rt cao (khong 80% sn lng kh khai thc c). Bi v vic s dng kh c tnh u vit nh sau:

t gy nhim mi trng.

Chi ph u t cho cng ngh s dng kh thp.

Hiu sut nhit cao. Thi gian xy dng ngn. Din tch xy dng nh my nh. Gi thnh sn xut 1 Kwh in t kh thp hn so vi cc loi nhin liu khc. Kh du m ha lng (LPG)Thnh phn ch yu ca LPG bao gm cc hydrocacbon parafinic nh propan, butan. Ngoi ra, ty thuc vo phng php ch bin m trong thnh phn ca n c th c mt mt lng nh olefin nh propylen, butylen.

Khi ha lng, th tch ca cc hydrocacbon gim, v d mt lt propan lng cho 270 lt hi 1 atm, 1 lt butan lng cho 238 lit hi 1 atm. V vy cng nh LNG, LPG c th vn chuyn, tn tr mt cch d dng v thun tin.

Nhit lng ta ra khi t LPG rt ln (khong 10900 n 13000 kcal/ kg tng ng vi vi nhit lng ca 1,5 n 2 kg than ci, 1,3 lit du ha hay 1,5 lit xng). Vi nhit lng c th s dng cho cc l cng nghip, lm nhin liu cho ng c t trong thay cho xng (trong cc loi t), lm nhin liu dn dng. Ngy nay trn th gii c xu hng s dng LPG thay cho nhin liu xng chy t, do n c nhiu u im hn hn so vi cc loi nhin liu khc l nhin liu chy hon ton, khng c khi, khng c tro, khng ln cc tp cht gy n mn cc phng tin bn b cha, khng gy nhim. Hm lng kh thi c hi nh NOx, COx rt t.

sn xut LPG, ngi ta va nn va lm lnh n nhit ha lng ca cht kh. V d, propan ha lng - 42,10C; izo butan - 110C; n butan - 0,50C.

Qua phn phn tch, so snh, nh gi v tng quan gi thnh trn n v nhit tr v hiu sut t chy gia cc loi nhin liu truyn thng, nhin liu kh thin nhin v LPG cho thy nu xt v phng din chi ph, th vic chuyn i cc nhin liu truyn thng sang s dng nhin liu kh thin nhin v LPG s tit kim c ng k chi ph cho nhin liu tnh trn u sn phm. Kh t c th t c nhit tr cung cp cao mt cch nhanh chng v cng h nhit nhanh khi ngng s dng. y l u im ln ca kh trong qu trnh nung, un, nu. Theo ti liu ca Unique Gas cung cp, hiu qu v nhit tr ca vic s dng kh vi cc loi nhin liu khc l: Bng 3.1. So snh nhit tr ca cc nhin liu

Nhin liuNhit tr (Kcal/ kg)T trng

in

Ci

Than ci

Than

Du F.O

Du D.O

Du th

Du ha

Nhin liu phn lc

Xng ng c

Kh du m ha lng (LPG)

Kh thin nhin ha lng (LNG)860

2662

6582

8171

10175

10675

10175 10840

11000

11400

11400

11845

124000,92 0,99

0,82 0,90

0,80 0,87

0,78 0,84

0,71 0,79

Bn cnh vic gim nhim mi trng kh dng kh thin nhin v LPG cn tit kim c khong 30 50% thi gian un nng do kh c nhit chy cao hn cc loi nhin liu khc v c hiu sut cao gp 1,5 ln so vi cc loi cht t khc. y l loi nhin liu sch, hiu sut chy cao, khng sinh khi v to mui khi chy.V nguyn tc LPG c s dng nh l mt ngun nguyn liu tin li sch s nht trong cc loi nhin liu thng dng. LPG c chia thnh 5 lnh vc s dng chnh: Dn dng v thng nghip: nu n, si m, n gas trong cc h dn, cc ca hng n ung v khch sn.

Cng, nng nghip: sy thc phm, nung gm s, hn ct

t: nhin liu cho xe con, xe taxi

Pht in: chy my pht in turbin.

Ha du: sn xut etylen, propylen, butadien cho ngnh nha v c bit sn xut MTBE l cht lm tng tr s octan.3.2. Phn on xng3.2.1. Thnh phn ha hc

Phn on xng bao gm cc hydrocacbon t C5 n C10, C11 c khong nhit si di 1800C. C 3 loi hydrocacbon parafinic, naphtenic, aromatic u c mt trong phn on. Tuy nhin thnh phn s lng cc hydrocacbon rt khc nhau, ph thuc vo ngun gc du th ban u. Chng hn, t h du parafinic s thu c xng cha parafin, cn t du naphtenic s thu c xng c nhiu cu t vng no hn.

Ngoi hydrocacbon, trong phn on xng cn c cc hp cht lu hunh, Nit v Oxy. Cc cht cha lu hunh thng dng hp cht khng bn nh mercaptan (RSH). Cc cht cha Nit ch yu dng pyridin; cn cc cht cha oxy rt t, thng dng phenol v ng ng. Cc cht cha nha v asphanten u cha c.

3.2.2. Xng lm nhin liu ng c xng

ng c xng l mt kiu ng c t trong, nhm thc hin chuyn ha nng lng ha hc ca nhin liu khi chy thnh nng lng c hc di dng chuyn ng quay. ng c xng bao gm ng c 4 k v ng c 2 k, trong ng c 4 k ph bin hn. Chu trnh lm vic ca ng c 4 k c th hin trong hnh 3.1.

Xng t thng nhin liu ca phng tin c bm chuyn n b ch ha kh (Carburettor), hoc h thng phun nhin liu c in t. Ti y n c phun sng v phi trn vi khng kh to thnh hn hp chy. Hn hp nhin liu v khng kh sau c a vo xylanh ng c thng qua ng gp u vo v van ht.

K ht: Piston i t im cht trn xung im cht di, van ht m ra ht hn hp xng v khng kh vo xylanh. Lc ny

van thi ng.

K nn: Piston i t im cht di ln im cht trn, lc ny van ht ng li nn hn hp xng v khng kh. Khi b nn, p sut tng (6-12 kg/cm2) dn n nhit tng (250 3500C), chun b cho qu trnh chy tip theo.

K chy: Khi piston ln n im cht trn th bugi nh la, s t chy hn hp xng v khng kh. Khi chy, nhit nng bin thnh c nng y piston xung im cht di, ng thi truyn chuyn ng qua thanh truyn lm chy my.

K x: Lc ny piston b y xung im cht di, v do qun tnh ca bnh piston tip tc i ln, van x s m ra kh chy thot ra ngoi v khi piston ln im cht trn th xylanh thi sch kh thi, van thi s ng li.

Khi piston bt u i xung th van ht li m ra v bt u cho mt chu trnh mi Bn cht ca qu trnh chy trong ng c xng

ng c lm vic bnh thng th trong xylanh, cc mt la phi lan truyn u n, ht lp n n lp kia, vi tc khong 15 n 40 m/s. Nu mt la lan truyn vi tc qu ln (ngha l s chy din ra cng mt lc trong xylanh) th xem nh l qu trnh chy khng bnh thng v c gi l chy kch n. l s chy rt nhanh hn hp nhin liu v khng kh trong bung t do nhit v p sut gia tng nhanh tip theo s chy khi u ca hn hp chung quanh bugi. nh hng ca thnh phn nhin liu n tnh cht chy trong ng c. Tr s octan.

Mt trong nhng tnh cht quan trng ca nhin liu xng l phi c kh nng chng li s kch n. c trng gi l tr s octan.

Tr s octan l mt n v o quy c dng c trng cho kh nng chng kch n ca nhin liu, c o bng phn trm th tch ca izo-octan (2,2,4 trimetylpentan C8H18) trong hn hp chun vi n-heptan (n C7H16), tng ng vi kh nng chng kch n ca nhin liu iu kin tiu chun. S dng thang chia t 0 n 100, trong n heptan c tr s octan bng khng v izo octan c quy c bng 100.

V nguyn tc, tr s octan cng cao cng tt, tuy nhin phi ph hp vi tng loi ng c. Xng c tr s octan t 80 n 83 thng c s dng cho cc loi xe c t s nn nh hn 7,5. Xng c tr s octan t 90 n 95 thng c s dng trong cc loi xe c t s nn cao trn 9,5 nh cc loi xe ua, xe t cao cp

C hai phng php xc nh tr s octan, phng php nghin cu (gi l tr s octan theo RON) v phng php mt (gi l tr s octan theo MON). im khc nhau ca hai phng php ch yu l do s vng quay ca mt th nghim.

Theo RON: L tr s octan ca xng th hin khi s dng trong ng c iu kin tc v ti trng trung bnh. S vng quay ca mt th nghim l 600 vng/ pht.

Theo MON: L tr s octan ca xng c trng cho iu kin hot ng khc nghit hn, l nhit u vo ca hn hp cao, ti trng ln, v ng c phi tri qua ch van tit lu m ht tc cao. S vng quay ca mt th nghim l 900 vng/ pht.

Thng thng, tr s octan theo RON thng cao hn MON. Mc chnh lch phn nh: mt mc no tnh cht ca nhin liu thay i khi ch lm vic ca ng c thay i, cho nn mc chnh lch cn gi l nhy ca nhin liu i vi ch lm vic thay i ca ng c. Mc chnh lch gia MON v RON cng thp cng tt.

Mi loi xng khc nhau c chng kch n cng khc nhau. Ngi ta thy rng:

Cc hydrocacbon phn t nh nh parafin mch nhnh, cc aromat ch chy c sau khi im ha, c ngha l loi ny c kh nng chng kch n tt.

Cc n parafin d dng chy gy c khi ngn la cha lan truyn ti, gy ra s chy kch n.

C th sp xp kh nng chng kch n ca cc hydrocacbon nh sau:

Hydrocacbon thm > olefin mch nhnh > parafin nhnh > naphten c nhnh > olefin mch thng > naphten > n parafin.

Nh vy, trong xng cha cng nhiu hydrocacbon thm hoc izo-parafin th tr s octan cng cao. Tr s octan ca mt s hydrocacbon ring r c th tham kho bng 4.6. Bng 3.2. Tr s octan ca mt s hydrocacbon khc nhau

HydrocacbonTr s octan chnh lch

PP RONPP MON

Cc parafin: Propan

n butan

izo butan

n pentan

izo pentan105,7

93,6

> 100

61,9

92,3100

90,1

99

61,9

90,35,7

3,5

-

0

2,0

Cc olefin:

Propylen

Buten 2

Penten 1

Hexen 1101,4

99,6

90,9

76,484,9

86,5

77,1

63,416,5

13,1

13,8

13,0

Cc naptalen:

Xyclopentan

Xyclohexan

Metyl xyclohexan

Etyl xyclohexan100

83

74,8

46,585

78,6

71

40,815

4,4

3,8

5,7

Cc hydrocacbon thm:

Benzen

Toluen

o - Xylen

m - Xylen

p - Xylen

1,3,5 - Trimetyl bezen

Izo - Propyl bezen113

115> 100

> 100

> 100

> 100

108111,6

102,1

100

> 100

> 100

114

99,31,4

12,9

-

-

-

-

8,7

Cc phng php nng cao cht lng ca xng

Phn on xng ly trc tip t du m c rt t izo parafin v hydrocacbon thm, nhiu n parafin, do tr s octan rt thp (ch t t 30 n 60), trong khi yu cu v tr s octan cho xng ng c phi ln hn 80. V vy phi dng nhng bin php khc nhau nng cao cht lng ca xng, ngi ta dng cc phng php sau y:

Phng php dng ph gia

Bn cht ca phng php ny l dng mt s ha cht pha vo xng nhm hn ch mt s qu trnh oxy ha ca cc hydrocacbon khng gian trc mt la khi chy trong ng c. Cc loi ph gia c chia lm hai nhm:

Ph gia ch bao gm cc cht nh tetrametyl ch (TML), tetretyl ch (TEL), c tc dng ph hy cc hp cht trung gian hot ng (peroxyt, hydroperoxyt) v do lm gim kh nng b chy kch n. Kt qu l tr s octan ca xng thc t c tng ln. C ch dng ph gia ch nh sau:

Phn hy TML trong ng c:

To cht khng hot ng:

Kt qu l bin cc peroxyt hot ng thnh cc aldehit (RCHO) bn vng, lm gim kh nng chy kch n. Nhng ng thi PbO kt ta s bm trn thnh xylanh, ng dn, lm tc ng nhin liu v tng mi mn. Do vy ngi ta dng cc cht mang a PbO ra ngoi. Cc cht mang thng dng l C2H5Br hoc C2H5Cl, c ch tc dng nh sau:

Cc sn phm PbBr2, H2O l cht lng, c nhit si thp s bc hi v c kh thi a ra ngoi. Hn hp ph gia ch v cht mang gi l nc ch. Nc ch rt c nn phi nhum mu phn bit. Phng php ha hc

Ph gia ch nh phn tch phn trn, ch l ph gia khi cho vo xng lm tng tr s octan nhiu nht (t 6 n 12 n v octan). Tuy nhin do tnh c hi m hin nay nhiu quc gia ban hnh lut cm s dng loi ph gia ny. Vit Nam, t thng 7 nm 2001 bt u chin dch khng s dng xng ch.

C mt s bin php hu hiu t tr s octan cao hn khi khng s dng ch:

Pha trn xng c tr s octan cao (nh xng alkyl ha, izomer ha) vo nhin liu c tr s octan thp.

Nng cp v a thm cc thit b lc du sn xut hn hp xng c tr s octan cao.

S dng cc ph gia khng cha ch, nh cc hp cht cha oxy: etanol, MTBE, ETBE, MTBA, TAME

Trong cc ph gia cha oxy ni trn, etanol v MTBE c s dng vi s lng nhiu nht. Chng hn nh M, MTBE c pha trn ti 15% th tch, etanol ti 10% th tch. Brazil pha trn ti 22% etanol vo xng trong nhiu nm.

Metanol khi dng pha ch thng c tr s octan cao tng t nh cc cht ph gia khc. u im ln nht ca ph gia ny l: gi tng i r, kh nng iu ch ph gia ny trong thin nhin tng i d dng. Metanol c th iu ch t cc nguyn liu th khc nhau. Nhc im ln nht ca ph gia ny l kh nng tan v hn ca n trong nc c th dn ti nhng hu qu khng tt.

Etanol khng c s dng rng ri nh metanol, n ch c s dng ch yu cc quc gia c sn ngun nguyn liu thin nhin l ma nh Brazil. Nhc im ca ph gia ny l ht m rt nhiu, lm tng nguy c chy n ca nhin liu v lm tng RPV ca nhin liu.

Ph gia Tert butyl alcol l sn phm trung gian ca oxyt propylen. C khong 800.000 tn TBA c sn xut trn ton th gii hng nm, trong khong 400.000 tn c sn xut chu u. Hin nay TBA c s dng pha ch vi metanol (t l 1: 1) hn hp theo t l ny s lm gim kh nng phn cch gia hai pha ca metanol, ng thi ci thin RPV ca hn hp. Nhc im ca ph gia ny l nhit chy mm kh cao ( v vy khng tn cha xng c ph gia ny nhit thp) v c kh nng ht m cao tuy khng nhiu nh metanol v etanol.

Ph gia Metyl tert butyl ete (MTBE) khi pha vo xng khng lm thay i RPV ca nhin liu. Kh nng ha tan vi nc ca MTBE thp hn nhiu so vi cc loi ru khc do vy lng nc ln vo nhin liu s t hn nhiu, s dng MTBE t nguy him hn so vi cc ph gia khc v nguy c gy chy n t hn so vi ru. Tuy nhin nhc im ln ca ph gia ny l gi thnh cao, trong khi lng dng trong xng kh ln (ti a n 15%). MTBE c iu ch bng phng php tng hp cc izo butylen, m izo butylen khng phi l loi nguyn liu d kim.

Bn cnh vic tng tr s octan, hn hp ca xng vi ph gia cha oxy gip gim thi hydrocacbon v CO t xe c s dng nhin liu.

C th thy r tr s octan ca mt s cht cha oxy in hnh trong bng 3.3.Bng 3.3. Tr s octan ca cc ph gia cha oxy

Ph gia cha oxyRONMON

Metanol

Etanol

Tert butyl alcol (TBA)

Metanol / TBA (50/50)

Metyl tert butyl ete (MTBE)

Tert amylmetyl ete (TAME)

Etyl tert butyl ete (ETBE)127 136

120 135

104 110

115 123

115 123

111 116

110 - 11999 104100 106

90 98

96 104

98 105

98 103

95 - 104

Bng 3.4.. c im ca mt s loi xng

Cc c tnhXng nh chng ct trc tipXng reformingXng CrckingXng Alkyl ha

T du th naphtenicT du th trung gianT du th parafinic

RON ban u

thm 0,5% nc ch

T trng d415

p sut hi bo ha Reid (bar)Thnh phn ct (ASTM):

Nhit si u

Nhit si 10%

Nhit si 50%

Nhit si 90%

Nhit si cui7787

0.721

0.43

52

69

83

103

1096985

0.685

0.59

42

56

68

84

1076582

0.682

0.59

40

55

71

93

979399

0.76

0.45

37

60

115

170

1809398

0.74

0.55

37

50

100

188

19597101

0.71

0.45

37

65

107

119

147

Bng 3.5. Ch tiu cht lng xng khng ch

Ch tiuXng khng chPhng php th

RON 92RON 97

1. Tr s octan, min

Theo phng php RON

Theo phng php MON92

-97

-ASTM D2699

2. Thnh phn phn on, 0C

10% V, max

50% V, max

90% V, max

im si cui, max

Cn cui, % V, max

Cn v hao ht % V, max70

120

190

210

2.0

4.070

120

190

210

2.0

4.0TCVN 2698 - 1995

3. axit, mg KOH/ 100ml, max3.03.0TCVN 2695 1995

4. n mn tm ng 500C, 3h, max1A1ATCVN 2694 1995

5. Hm lng nha thc t mg/ 100ml, max5.05.0ASTM D381

6. n nh oxy ha, pht, min360360ASTM D1266

7. Hm lng lu hunh tng, % kh. l. , max0.10.05ASTM D1266

8. Hm lng ch, g/l, max0.0130.013ASTM D3237

9. p sut hi bo ha/ Reid 37,80C, kPa, max8383ASTM D4953

10. Hm lng benzen, %kh.l., max55ASTM D3606

11. Hm lng MTBE, % V, max1010ASTM D4815

Bng 3.6. Tng quan v s phn loi xng t trn th gii hin nayPhn loiCh tiu c trng cho s phn loi

Tr s octan, minHm lng ch

1. Xng ch thng dngMON 72, RON 80t 0.15 n 0.8 g/l

2. Xng ch c cht lngMON 86, RON 92T 0.15 n 0.6 g/l

3. Xng khng ch c cht lngMON 85, RON 92Max: 0.015 g/l

4. Xng khng ch c bitMON 90, RON 95Khng

Xng my bay

Xng my bay thuc loi xng cao cp, khng th ly c ly c t mt loi xng thun nht m thng l hn hp ca mt s thnh phn c bit nhm thu c xng c phm cht tt. Xng my bay phi c nhng tiu chun cn thit sau y.

Tr s octan bng hoc ln hn 100, ngoi ra phi m bo tr s octan khi hn hp chy thiu xng, tha khng kh v hn hp chy tha xng, thiu khng kh. ng c my bay khi lm vic c hai qu trnh: qu trnh ct cch bao gi cng phi s dng cng sut ti a, lng xng trong hn hp phi c tng ti a (gi l hn hp giu). Trong qu trnh bay, c lc ng c phi gim cng sut, lng xng gim (hn hp ngho). Tr s octan trong trng hp hn hp giu gi l tr s phm . Ngi ta th hin tr s octan ca xng my bay bng phn s, trong : t s l tr s octan, mu s l tr s phm . V d xng loi B 100/ 130 th 100 l tr s octan, 130 l tr s phm .

Thnh phn ct phn on ca xng my bay phi ly hp (t 40 n 1800C) trnh c nhiu cu t nh to nt hi trong h thng cp liu, v c nhiu cu t nng, v khi chy s chy khng hon ton to cn.

Hm lng olefin phi thp (< 3%) trnh s trng hp to nha, lm cho xng b bin mu v khng bo qun c lu.

Xng my bay thng l xng pha trn, v d, xng loi B 100/ 130 thu c bng cch trn xng cracking xc tc vi nhng thnh phn cao octan nh izo-octan. Xng B 91/ 115 l xng pha trn gia xng crking xc tc, xng chng ct trc tip v thnh phn cao octan. Bng 4.13 cho bit ch tiu cht lng ca xng my bay theo tiu chun ca Lin X (c).3.2.3. Cc ng dng khc ca xng

Ngoi cng dng chnh l nhin liu, xng cn c s dng lm dung mi hoc nguyn liu cho tng hp ha du. Xng lm dung mi

Phn on xng c s dng lm dung mi trong cng nghip sn, cao su, keo dn, ngoi ra cn s dng trch ly cht bo, trong cng nghip hng liu, dc liu

Trong cc loi dung mi, ph bin l xng parafinic v aromatic. Thng thng xng dung mi ly trc tip t du m l xng parafinic, c hm lng hydrocacbon thm thp. Cc lnh vc ng dng khc nhau ca xng xem bng 4.12. Xng lm nguyn liu cho tng hp ha du

Xng s dng lm nguyn liu cho tng hp ha du cn gi l phn on naphta. T phn on ny ngi ta sn xut c cc hydrocacbon thm khc nhau nh benzen, toluen, xylen. Ngoi ra, cn thu c cc olefin nh nh etylen, propylen, butadien

thu c cc hydrocacbon thm (BTX), ngi ta s dng cc phn on hp khi chng ct.

Bng 3.7. Cc ng dng ca xng dung mi

Loi dung miKhong si 0CMc ch s dng

AB

C

D

E

F

G

White Spirit40 10060 80

70 100

95 103

100 130

100 160

30 75

135 205Keo, cao su, ty vt mTrch ly du m, cht bo, ch to nc hoa

Trch ly du m, cht bo, cng nghip cao su

Kh nc ca ruCng nghip cao su, sn, ty bn

Cng nghip cao su, sn.

Trch ly hng liu, sn xut dc liu.

Sn, vecni (thay du thng)

Phn on 60 850C: Phn on cha metyl xyclopentan, xyclohexan cho hiu sut benzen cao nht.

Phn on 80 1000C: Phn on cha naphten C7, cho hiu sut toluen cao nht.

Phn on 105 1400C: Phn on cha naphten C8, cho hiu sut xylen cao nht.

Xng dng ch bin ha hc cn phi rt sch, v nu trong xng c nhiu S, N, O s lm ng c xc tc trong qu trnh ch bin. V vy yu cu v hm lng cc cht d th v kim loi nng c trong xng phi nh sau:

Hm lng S (10 15). 10-4 % trng lng

Hm lng N 1. 10-4 % trng lng

Hm lng Hg, Pb 5. 10-6 % trng lng

Hm lng As 1. 10-7 % trng lng

3.3. Phn on Kerosen

Phn on ny cn gi l du la: c nhit si t 180 n 2500C, bao gm cc hydrocacbon c s cacbon t C11 n C16.3.3.1. Thnh phn ha hc

Trong phn on ny, hu ht l cc parafin, rt t izo parafin. Cc hydrocacbon naphtenic v thm mt vng nhiu nhnh ph ngoi ra cn c mt cc hp cht hai hoc ba vng, c bit loi naphten v thm hai vng chim a s.3.3.2. ng dng

Phn on kerosen s dng ch yu cho hai mc ch: lm nhin liu phn lc v du ha dn dng, trong nhin liu phn lc l ng dng chnh. Kerosen lm nhin liu phn lc

ng c phn lc (Hnh 3.2).

Tuabin chnh ch s dng mt phn ng nng ca sn phm chy bung t nhm lm quay tuabin my nn, phn ng nng quan trng cn li s c gin n qua tuy-e ra ngoi vi tc rt ln, to nn mt phn lc tc ng ln ng c, y ng c tin ln pha trc. y l ng c phn lc tuabin.

Hnh 3.2. ng c phn lc

Ch thch:

1. Tuabin my nn khng kh a vo bung t.

2. Tuabin chnh, bin mt phn ng nng ca dng kh thnh chuyn ng quay, lm quay tuabin my nn.

3. Bung t chnh

4. Bung t ph

nh hng ca bn cht nhin liu n qu trnh chy: nhin liu dng trong ng c phn lc c ch to t kerosen hoc t hn hp gia phn on kerosen vi phn on xng.

Yu cu ca nhin liu phn lc l d chy bt k iu kin p sut v nhit no, chy iu ha, khng b tt trong dng khng kh c tc xoy ln.

m bo c nhit tr cao, nhin liu khng cha nhiu thnh phn aromatic m ch yu l parafinic v naphtenic.

Nhng an ton cho my bay hot ng cao ln, nhit thp cn hn ch thnh phn parafinic d b kt tinh v tng cng thnh phn naphtenic nhiu vng. Cn phi ch n kh nng to cn, to cc ca nhin liu gy nh hng xu n tnh nng hot ng ca ng c. Kh nng c xp theo chiu gim dn nh sau:

Aromatic > olefin > izo-parafin, naphten > n-parafin

nh gi kh nng to cn cacbon, ngi ta dng i lng chiu cao ngn la khng khi, l chiu cao ti a ca ngn la khng c khi tnh bng mm, khi t nhin liu trong n du tiu chun. Chiu cao ngn la khng khi cng cao chng t nhin liu chy cng hon ton. Chiu cao cng thp, kh nng to cn cacbon cng ln. Nhng thnh phn khng phi hydrocacbon cha trong nhin liu u c nh hng xu n tnh cht s dng ca nhin liu. Cc hp cht lu hunh khi chy to ra cc cht c tnh axit gy n mn nhit thp. Cc hp cht cacbon cn gy ra cn cacbon trong bung t. Cc hp cht oxy, nh axit naphtenic, phenol u lm tng kh nng n mn cc thng cha, ng dn nhin liu v cc sn phm to ra do n mn (cc mui kim loi ca axit naphtenic) li gp phn to cn to tro khi chy bm vo bung t, ch yu l nn in, vi phun, tuy-e thot sn phm gy tr ngi cho qu trnh.

Cc hp cht Nit lm nhin liu km n nh, bin mu ca nhin liu. cc kim loi nht l Vanadi, Natri nm trong sn phm chy nhit cao 6500C n 8500C khi p vo cc tuabin s gy n mn hp kim hoc gy ph hoi cc chi tit tuabin, v vy hm lng kim loi v tro trong nhin liu phi rt nh, khong vi phn triu. Kerosen lm du ha dn dng.

T phn on kerosen, vi khong si 200 n 3100C c th sn xut du ha, s dng lm du ha dn dng nh thp sng, un nu. c tnh quan trng ca du ha l chiu cao ngn la khng khi. m bo ngn la sng, p, r, u, chiu cao ny phi ln hn 20 mm.

Thnh phn ha hc ca du ha nh hng cn bn n s chy. Du ha c cha nhiu thnh phn hydrocacbon thm trong khi chy s to nhiu mui khi. Cht keo v axit naphten lm tc bt trong mung n, lm gim nh sng khi t chy. Trong thnh phn ca du ha dn dng ch c parafinic v naphten c s nguyn t cacbon trong phn t t 10 n 14. y l cc cht chy tt cho ngn la xanh, nhit tr cao.

Nu trong nhin liu cha nhiu lu hunh, khng nhng gy c hi trc tip cho ngi s dng m cn lm cho bng n m i, khng m bo cng chiu sng ca ngn la. Ch tiu v du ha dn dng ca Vit Nam xem bng 3.8.Bng 3.8. Ch tiu du ha dn dng theo tiu chun Vit Nam

Cc ch tiuPhng php thMc quy nh

Mu SayboltASTM D156Min 20

Axit tng, mg KOH/gASTM D3242Max 0,002

Chiu cao ngn la khng khi, mmASTM D1322Min 19

Thnh phn ct phn on, 0C im si u

im ct 50%

im si cui

Cn trung bnhMin 144

Min 200

Min 277

Max 1,00

Hm lng lu hunh, %KlASTM D1266Max 0,1

im chp chy cc kn, 0CASTM D93Min 36

Lng nha thc t, mg/100mlASTM D381Max 1,0

nht 200C, cStASTM D445Max 3,5

n mn tm ng, 2h/1000CASTM D1301,0

Khi lng ring 150C, g/cm3ASTM D1298Max 0,83

3.4. Phn on Gasoil nh

Gasoil nh, cn gi l phn on du izen, c khong nhit si t 250 n 3500C, cha cc hydrocacbon t C16 n C21.

3.4.1. Thnh phn ha hc

Phn ln trong phn on ny l cc n-parafin, izo-parafin cn hydrocacbon thm rt t.

Hm lng cc cht cha S, N, O tng nhanh. Lu hunh ch yu dng disunfua, d vng. Cc cht cha oxy ( dng axit naphtenic) c nhiu v t cc i phn on ny. Ngoi ra cn c cc cht dng phenol nh dimetylphenol. Trong gasoil xut hin nha, song cn t, trng lng phn t ca nha cn thp (300 n 400 .v.C).3.4.2. ng dng ca phn on Gasoil nh

Phn on Gasoil ca du m ch yu c s dng lm nhin liu cho ng c izen ng c izen

1 - Thanh truyn; 2 - Xylanh; 3 - Piston; 4,7 - Vi phun nhin liu

5 - Van np khng kh; 6 - Van thi sn phm; 8 - im cht trn

9 - im cht di

Hnh 3.3. M hnh bung t ca ng c izen

ng c xng c t s nn thp hn so vi ng c izen. Vi ng c xng, t l l t 7/1 n 11/1, cn ng c izen l t 14/1 n 17/1, v vy ng c izen c cng sut ln hn ng c xng trong khi tiu hao cng mt lng nhin liu.

Nguyn l lm vic: Khi piston i t im cht trn xung im cht di, van np m ra, khng kh c ht vo xy lanh; sau van np ng li, piston li i t im cht di ln im cht trn, thc hin qu trnh nn khng kh. Do b nn, p sut tng, dn n nhit tng c th ti 500 n 7000C. Khi piston ln n gn im cht trn nhin liu c phun vo xy lanh (nh bm cao p) di dng sng, khi gp khng kh nhit cao s t bc chy. Khi chy p sut tng mnh y piston t v tr im cht trn xung im cht di thc hin qu trnh dn n sinh cng c ch v c truyn qua h thng thanh truyn lm chy my. Piston sau li i t im cht di ln im cht trn thi sn phm chy ra ngoi qua mt van thi v tip tc thc hin chu k mi. Bn cht ca qu trnh chy

Nhin liu sau khi phun vo xylanh khng t chy ngay m phi c mt thi gian oxy ha su cc hydrocacbon trong nhin liu, to hp cht cha oxy trung gian, c kh nng t bc chy. Khong thi gian gi l thi gian cm ng hay thi gian chy tr. Thi gian cm ng cng ngn cng tt, lc nhin liu s chy iu ha.

Nh vy, c thi gian chy tr ngn th trong nhin liu phi c nhiu cc cht n parafin, v cc cu t ny d b oxy ha, tc l d t bc chy, cn cc izo parafin v cc hp cht hydrocacbon thm rt kh b oxy ha nn thi gian chy tr di, kh nng t bc chy km. C th sp xp th t theo chiu gim kh nng oxy ha (tc l thi gian cm ng) ca cc hydrocacbon nh sau:

n parafin < naphten < n olefin < izo naphten < izo parafin < izo olefin < hydrocacbon thm.

Tr s xetan

c trng cho kh nng t bc chy ca nhin liu izen, ngi ta s dng i lng tr s xetan. Tr s xetan l n v o quy c, c trng cho kh nng t bc la ca nhin liu izen, l mt s nguyn, c gi tr ng bng gi tr ca hn hp chun c cng kh nng t bt chy. Hn hp chun ny gm hai hydrocacbon: n xetan (C16H34) quy nh l 100, c kh nng t bc chy tt v - metyl naphtalen (C11H10) quy nh l 0, c kh nng t bc chy km. Cc hydrocacbon khc nhau u c tr s xetan khc nhau: mch thng cng di, tr s xetan cng cao, ngc li, hydrocacbon thm nhiu vng, tr s xetan thp.

Nu tr s xetan qu cao s khng cn thit v gy lng ph nhin liu, mt s thnh phn nhin liu trc khi chy, nhit cao trong xylanh b thiu oxy nn phn hy thnh cacbon t do, to thnh mui.

Nu tr s xetan thp s xy ra qu trnh chy kch n do: trong nhin liu c nhiu thnh phn kh b oxy ha, khi lng nhin liu phun vo trong xylanh qu nhiu mi xy ra qu trnh t chy, dn n chy cng mt lc, gy ta nhit mnh, p sut tng mnh, ng c run git, gi l chy kch n.

tng tr s xetan c th thm vo nhin liu cc ph gia thc y qu trnh oxy ha nh: izo propylnitrat, n butylnitrat, amylnitratvi lng khong 1,5% th tch, cht ph gia c th lm tng tr s xetan ln 15 n 20 n v.

3.5. Phn on Gasoil nng (Phn on du nhn)

Vi khong si t 350 n 5000C, phn on ny bao gm cc hydrocacbon t C21 n C35 hoc c th ln ti C40.

3.5.1. Thnh phn ha hc

Do c phn t lng ln, thnh phn ha hc ca phn on du nhn rt phc tp: Cc n - parafin v izo - parafin t, naphten v thm nhiu. Dng cu trc hn hp tng.

Hm lng cc hp cht ca S, N, O tng mnh: hn 50% lng lu hunh c trong du m tp trung phn on ny, gm cc dng nh disulfua, thiophen, sulfua vng Cc cht Nit thng dng ng ng ca pyridin, pyrol v cacbazol. Cc hp cht oxy dng axit. Cc kim loi nng nh V, Ni, Cu, PdCc cht nha, asphanten u c mt trong phn on.

Thng thng ngi ta tch phn on du nhn bng cch chng ct chn khng phn cn du m, trnh phn hy cc cht nhit cao.

3.5.2. ng dng ca phn on sn xut du nhn

Cng dng ca du bi trn

Cng dng lm gim ma st

Mc ch c bn ca du nhn bi trn gia cc b mt tip xc ca cc chi tit chuyn ng nhm gim ma st. My mc s mn ngay nu khng c du bi trn. Nu chn ng du bi trn th h s ma st gim t 100 n 1000 ln so vi ma st kh. Khi cho du vo my vi mt lp dy, du s xen k gia hai b mt. Khi chuyn ng, ch c cc phn t du nhn trt ln nhau. Do my mc lm vic nh nhng, t b mn, gim c cng tiu hao v ch.

Cng dng lm mt

Khi ma st, kim loi nng ln, nh vy mt lng nhit sinh ra trong qu trnh . Lng nhit ln hay nh ph thuc vo h s ma st, ti trng, tc . tc cng ln th lng nhit sinh ra cng nhiu, kim loi s b nng lm my mc lm vic mt chnh xc. Nh trng thi lng du chy qua cc b mt ma st em theo mt phn nhit truyn ra ngoi, lm cho my mc lm vic tt hn.

Cng dng lm sch

Khi lm vic, b mt ma st sinh ra mn kim loi, nhng ht rn ny s lm cho b mt cng tc b xc, hng. ngoi ra c th c ct, bi, tp cht ngoi ri vo b mt ma st. Nh du nhn lu chuyn qua cc b mt ma st, cun theo cc tp cht a ra cacte du v c lng lc i. Cng dng lm kn

Trong cc ng c c nhiu chi tit truyn ng cn phi lm kn v chnh xc nh piston xylanh, nh kh nng bm dnh to mng, du nhn c th gp phn lm kn cc khe h, khng cho hi b r r, m bo cho my lm vic bnh thng.

Bo v kim loi

B mt my mc, ng c khi lm vic thng tip xc vi khng kh, hi nc, kh thilm cho kim loi b n mn, h hng. nh du nhn c th lm thnh mng mng ph kn ln b mt kim loi nn ngn cch c vi cc yu t trn, v vy kim loi c bo v.

Phn loi du nhn

Theo ngha s dng, du nhn c 2 loi chnh, l:

Du nhn s dng cho mc ch bi trn (gi l du ng c)

Du nhn khng s dng cho mc ch bi trn (du cng nghip)

Trong thc t, du ng c chim mt t l kh ln trong cng nghip sn xut du bi trn ni chung (khong 40%) v c s dng ph bin.

Cc c trng c bn ca du bi trn

nht

nht ca mt s phn on du nhn l mt i lng vt l c trng cho tr lc do ma st ni ti ca n sinh ra khi chuyn ng. Do vy nht c lin quan n kh nng bi trn ca du nhn.

thc hin nhim v bi trn, du nhn phi c nht thch hp, phi bm chc ln b mt kim loi v khng b y ra ngoi, ngha l n phi c ma st ni ti nh.

nht ca du nhn ph thuc ch yu vo thnh phn ha hc.

Cc hydrocacbon parafinic c nht thp hn so vi cc loi khc. chiu di v phn nhnh ca mch hydrocacbon cng ln, nht s tng ln.

Cc hydrocacbon thm v naphten c nht cao. c bit s vng cng nhiu th nht cng ln. Cc hydrocacbon hn hp gia thm v naphten c nht cao nht.

nht ca du nhn thng c o bng poaz (P), centipoaz (cP), hoc stc (St), centistc (cSt). Ch s nht

Mt c tnh c bn na ca du nhn l s thay i nht theo nhit . Thng thng, khi nhit tng, nht s gim. Du nhn c xem l du bi trn tt khi nht ca n t b thay i theo nhit , ta ni rng du c ch s nht cao. ngc li nu nht thay i nhiu theo nhit , c ngha l du c ch s nht thp.

Ta c th xc nh ch s nht VI theo ton hnh 4.4.

Cch xc nh nh sau: t thc ni 2 im gi tr nht 400C v 1000C, im ct s l gi tr ch s nht VI cn tm.

Hnh 4.4. Ton xc nh ch s nht VI

Sn xut du nhn

thc hin c chc nng bi trn tt, du nhn phi c nht kh cao duy tr c mng du lin tc, mt khc ch s nht phi cao khi my mc lm vic nhit thng, cng nh nhit cao nht t b thay i (c ngha l du phi c ch s nht cao). t c mc ch trn, nguyn liu tt nht sn xut du nhn gc l:

Cc n parafin sau khi tch bt cc cht c phn t lng qu ln trnh s kt tinh.

Cc hydrocacbon naphtenic hoc thm t vng, c nhnh ph di; cc cu t ny l nguyn liu l tng sn xut du nhn gc, v chng va c nht cao (tnh cht ca cc vng naphten, vng thm); va cho ch s nht cao (tnh cht ca nhnh ph - parafin).

Sau khi c du nhn gc, sn xut du nhn thng phm, ngi ta phi pha thm cc ph gia nhm mc ch tng cng cc tnh cht sn c, hoc to ra nhng kh nng m trong du nhn gc cha c. Ph gia pha ch du bi trn phi p ng c cc yu cu: tan trong du gc, n nh ha hc, khng c hi, c tnh tng hp, bay hi thp v khng phn ng ha hc vi nhau. Cc loi ph gia thng l:

Ph gia chng oxy ha bao gm cc dn xut ca phenol, amin nh:

Ph gia tng ch s nht

Ph gia c ch n mn

Ph gia ty ra

Ph gia h im ng v nhiu cc loi ph gia khc.

3.5.3. ng dng ca phn on sn xut sn phm trng

Cc sn phm trng l tn gi ca ba loi nhin liu: Xng, kerosen, izen. l cc loi nhin liu c s dng nhiu nht, quan trng nht. lm tng s lng cc nhin liu ny, c th tin hnh phn hy gasoil nng bng phng php crking hoc hydrocrking. Vi cch ny, c th bin cc cu t C21 n C40 thnh xng (C5 n C11), kerosen (C11 n C16), izen (C16 n C20), nh vy, nng cao hiu sut s dng ca du m.

3.6. Phn on cn du m (cn gudon)3.6.1. Thnh phn ha hc

Gudron l phn cn li sau khi phn tch cc phn on k trn c nhit si ln hn 5000C, gm cc hydrocacbon c s nguyn t cacbon ln hn C41, gii hn cui cng c th ln n C80.

Thnh phn ca phn on ny rt phc tp. C th chia thnh 3 nhm chnh sau:

Nhm cht du

Nhm cht du bao gm cc hydrocacbon c phn t lng ln, tp trung nhiu cc hp cht thm c ngng t cao, cu trc hn hp nhiu vng gia thm v naphten, y l nhm hp cht nh nht, c t trng xp x bng 1, ha tan trong xng, n pentan, CS2 nhng khng ha tan trong cn. Trong phn on cn nhm du chim t 45 n 60%. Nhm cht nha

Nhm ny dng keo qunh: gm hai nhm thnh phn l cht trung tnh v cht axit.

Cc cht trung tnh c mu en hoc nu, nhit ha mm nh hn 1000C, t trng ln hn 1, d dng ha tan trong xng, naphta. Cht trung tnh to trong nha c tnh do dai v tnh dnh kt. Hm lng ca n nh hng trc tip n tnh ko di ca nha, chim khong 10 n 15% khi lng ca cn gudron.

Cc cht axt l cht c nhm COOH, mu nu sm, t trng ln hn 1, d ha tan trong cloruaform v ru etylic, cht axit to cho nha c tnh hot ng b mt. Kh nng kt dnh ca bitum ph thuc vo hm lng cht axit c trong nha, n ch chim khong 1% trong cn du m.

Nhm asphanten

Nhm asphanten l nhm cht mu en, cu to tinh th, t trng ln hn 1, cha phn ln cc hp cht d vng c kh nng ha tan mnh trong cc disunfua (CS2). un 3000C khng b nng chy m b chy thnh tro.

Ngoi ba nhm cht chnh ni trn, trong cn gudron cn c cc hp cht c kim ca kim loi nng, cc cht cacbenkhng tan trong cc dung mi thng thng, ch tan trong pyridin3.6.2. ng dng ca phn on cn gudron

Phn on gudron c s dng trong nhiu mc ch khc nhau nh sn xut bitum, than cc, nhin liu t l. Trong cc ng dng trn, sn xut bitum l ng dng quan trng nht.

Sn xut bitum

Thnh phn ha hc ca bitum

Bitum l hn hp phc tp ca nhiu loi cht, trong hm lng cc nguyn t thu c nh sau:

Bng 4..8. Thnh phn nguyn t ca bitum

Cacbon

Hydro

Lu hunh

Nit

Oxy(C)

(H)

(S)

(N)

(O)80 87%

10 15%

2 8%

0,5 2%

1 5%

Trong cc nguyn t k trn, hm lng cacbon v hydro chim mt t l tng i ln. Qua thy rng nhm du l b phn ch yu to thnh bitum.

Cc cht asphanten quyt nh tnh rn ca bitum, c ngha l mun bitum cng rn th hm lng asphanten cng cao.

Cc cht nha quyt nh tnh do v kh nng gn kt ca bitum

Cc cht du lm tng kh nng chu ng sng gi, nng ma ca bitum.

Mt loi bitum tt, chu thi tit tt, c cao th phi c thnh phn nh sau: 25% nha, 15 n 18% asphanten, 52 n 54% du. T l gia asphjanten v nha khong 0,5 n 0,6. T l nha so vi du t 0,8 n 0,9.

Cn du m cha nhiu parafinic rn l nguyn liu xu nht sn xut bitum. Bitum s c bn thp, tnh gn kt km do c nhiu hydrocacbon khng phn cc. Ngc li cn du m loi aromatic hoc naphten aromtic l nguyn liu rt tt sn xut bitum. Mt s tnh cht c trng ca bitum

xuyn kim: l i lng c trng cho qunh ca bitum, c tnh bng milimt chiu su ln xung ca kim t di ti trng 100g trong thi gian 5 giy 250C. ln kim cng nh, bitum cng qunh.

dn di: l i lng c trng cho tnh do ca bitum, c tnh bng cetimet khi ko cng mt mu c tit din quy nh 250C vi tc ko l 5 cm/ pht. dn di cng ln th tnh do ca bitum cng cao.

Tnh n nh nhit: khi nhit thay i, tnh cng, tnh do ca bitum cng thay i. Nu s thay i cng nh th tnh n nh ca bitum cng cao.

Tnh n nh vi thi gian: L kh nng ca bitum chng li tc ng ca mi trng xung quanh. Do nh hng ca thi gian m tnh cht v thnh phn ca bitum thay i. S thay i gi l s ha gi ca bitum.

Tnh n nh ca bitum du m tng i cao, thng th sau 10 n 15 nm s dng, cc tnh cht ca n mi thay i r rt.

ng dng ca phn on cn lm nhin liu t l

C th s dng trc tip phn on cn du m lm nhin liu t l. Nhit nng ca nhin liu ny vo khong 10.000 kcal/ kg. T l gia C v H cng thp, nhit nng ca du cng cao.

Nu trong nhin liu ny c hm lng cc kim loi nng ln, khi chy s to thnh hp kim vi st c nhit nng chy thp, dn n thng l.

CHNG 4

C S L THUYT CA QU TRNH CHNG CT4.1. C s l thuyt

Qu trnh chng ct du l mt qu trnh phn chia vt l du th thnh cc phn on. Ty theo cch tin hnh m ngi ta chia qu trnh chng ct thnh: chng ct n gin v chng ct phc tp.

Chng ct n gin: chng ct bay hi dn dn, chng ct bay hi mt ln v nhiu ln

Chng ct phc tp: chng ct c hi lu, chng ct c tinh luyn

Chng ct trong chn khng v chng ct c hi nc

Chng ct chn khng v chng ct vi hi ncHn hp cc cu t c mt trong du khng bn nhit cao (h.c cha lu hunh < cc cht cao pt < parafin < naphten < aromatic)

Khi nhit si ca hn hp p sut kh quyn cao hn nhit phn hy, ngi ta phi dng chng ct chn khng (VD) hay chng ct vi hi nc (gim p sut hi ring phn, gim nhit si)

Tuy nhin nhit lng bay hi ca nc khc xa vi nhit t nng cht lng. Khi tng lng hi nc s lm gim Phbhca du, dn n gim s tch hi. Ti u nht l lng hi nc khong 2 3% nguyn liu. Khi tin hnh chng ct, nhit hi nc (380 4500C) phi thp hn nhit hi du.

u im ca chng ct hi nc: tng cng khuy trn, tng b mt bay hi, t nng cn du trong l ng khi chng chn khng, trnh v ngn nga qu trnh to cc trong l ng

4.2. Cc thng s cng ngh nh hng n qu trnh

Cc thng s cng ngh nh hng trc tip ti hiu sut v cht lng ca qu trnh chng ct l: nhit , p sut, phng php chng ct

Ch nhit ca thp chng luyn

Ch nhi ca thp gm: nhit ca nguyn liu vo thp, nhit nh thp, nhit trong thp v y thp.

Nhit ca nguyn liu (du th) vo thp chng c khng ch ty theo bn cht c aloi du th, mc cn phn chia sn phm, p sut trong thp v lng hi nc a vo y thp; nhng ch yu l phi trnh c s phn hy nhit ca nguyn liu nhit cao. Do vy, nhit l ng t nng phi c khng ch cht ch.

Nhit y thp chng luyn ph thuc vo phng php bay hi v phn hi lu y. Nu bay hi phn hi lu y bng mt thit b t nng ring bit (reboiler), th nhit y thp s ng vi nhit bc hi cn bng p sut ti y thp. Nu bc hi bng cch dng hi nc qu nhit th nhit y thp s thp hn nhit vng np liu. Nhit y thp phi chn ti u, trnh s phn hy cc cu t nng nhng phi tch ht hi nh khi phn cn y.

Nhit nh thp c khng ch nhm m bo c s bay hi hon ton sn phm nh m khng gy ra s cun theo cc phn nng khc. Mun vy ngi ta phi dng hi lu nh thp. tch xng khi cc phn on kh, nhit nh thp khi chng ct p sut kh quyn cn gi trong khong 100 1200C, cn vi thp chng chn khng khi p sut chng l 10 70mmHg thng khng qu 1200C tch ht phn gasoil nh cn ln trong nguyn liu

Dng hi lu s to iu kin phn chia tt hn. Hi lu nh thp c 2 dng: hi lu nng v hi lu ngui.

Ngoi hi lu nh v y, ngi ta cn s dng hi lu trung gian tng cht lng cc sn phm cnh sn v iu chnh nhit trong thp.

p sut ca thp chng

Khi chng ct du m p sut kh quyn, p sut tuyt i trong thp thng cao hn mt cht so vi p sut kh quyn, v mi phn ly sn phm ra, p sut cng c khc nhau, ph thuc vo vic tng hay gim nhit sn phm ly ra khi thp. p sut trong thp chng ct c khng ch bng mt b phn iu chnh p sut t thit b ngng t.

Khi chng p sut chn khng, p sut c khng ch trong khong t 10 70mmHg. chn khng cng su, cng cho php chng su hn, song nu p sut qu thp s kh cho ch to thit b vi nng sut ln.

S lm vic n nh ca thp chng ph thuc vo p sut trong thp. iu ny thy r trong phn di y.

iu khin, khng ch ch lm vic ca thp chng ct:

iu hnh s lm vic n nh ca thp chng ct, chng ta cn phi nm vng cc nguyn tc sau:

1. iu chnh p sut trong thp lm thay i im si ca cht lng

2. Nu p sut tng ln, cht lng si nhit cao hn, nu p sut tgn cao qu , lng cht lng trong thp nhiu v nh vy s dn n hin tng sc lm gim hiu qu phn chia.

3. Nu cc iu kin khc trong thp l c nh, th sn phm nh, sn phm cnh sn v sn phm y tr nn nh hn nu p sut trong thp tng ln.

4. Nu nhit y qu thp, sn phm y s cha nhiu phn nh.

5. Nu nhit cp liu vo thp qu thp, lng hi trn cc khay cha a s nh, vy phn lng s nhiu v chng chy xung pha di vo b phn chng s cng nhiu.

6. Nu nhit ca reboiler qu thp (vi s chng ct c reboiler) s khng tch ht phn nh trong cn v lm tng phn cn.

7. Nu nhit nh qu cao, sn phm nh s qu nng v c nhiu sn phm hn so vi thit k v ngc li, nu nhit nh qu thp, sn phm nh s qu nh v c t sn phm hn.

8. Nhit cn thit tch phn on du th nng s cao hn so vi du th loi nh.

9. Ch nht l nhit nh thp, trnh nhit qu cao m nguyn nhn c th l do lm lnh khng , dn n thay i ch hi lu, nh hng nhiu n cht lng sn phm.

Chng 5

CC QU TRNH CHUYN HA HA HC DI TC DNG NHIT5.1. S bin i ca cc hyrocacbon di tc dng nhit

5.1.1. S bin i ca RH parafinic

Cc RH parafinic l hyrocacbon no, trong phn t ch c 2 lin kt chnh: l lin kt C-C v C-H. Lin kt C-C km bn nhit hn lin kt C-H, nn di tc dng ca nhit cao s xy ra s phn hy c mch lin kt C-C trc. Khi to thnh RH c trng lng phn t thp hn.

Nu phn t parafin mi to thnh cn c mch di, n li b phn hy tip. Ch khi s nguyn t cacbon nh hn 4, lc ny parafin kah1 bn v kh b a lin kt C-C, nn khi xy ra s t lin kt C-H, to thnh hyro.

V tr t mch C-C ph thuc nhiu vo iu kin tin hnh qu trnh nh nhit , p sut v thi gian lu ca hn hp phn ng nhit . Nu nhit cng cao v p sut cng htp, v tr t mch c xc sut ln hn u mch, do vy m iu kin ny s cho sn phm kh nhiu hn. Nhng nu nhit va phi (450 5300C) v p sut cao th v tr t mch li c xc sut ln v tr gia mch. Do iu ny d to iu kin thun li tng hiu sut sn phm lng. l c s quyt nh iu kin cng ngh khc nahu gia cracking nhit v Pyrolise.

C ch ca cc phn ng c ngh l chui gc v xy ra qua cc giai on sau:

To gc t do (khi mo)

Pht trin chui trn c s gc t do

Dng phn ng (tt mch chui)

5.1.2. S bin i ca cc hp cht olefin

Trong du th ban u, hm lng olefin khng ng k. Nhnh di tc dng ca nhit 6 cao, cc hp cht olefin s c to thnh. Chng c kh nng phn ng coa hn so vi parafin v kh nng bin i a dng cng ph thuc vo iu kin tin hnh phn ng (p sut, nhit ). iu kin nhit thp v p sut cao, olefin c trng lng phn t thp d b trng hp, phn ng trng hp cng mnh nu p sut cng tng cao. Nhng nu tng nhit th tc phn ng trng hp li gim xung nhng ch cho phn ng phn hy, v nu thi gian lu trong vng phn ng cao lu, th s phn hy phn ng cng xy ra mnh lit. C ch phn hy olefin cng ging nh parafin, nhng phn ng thun li l t mch lin kt C-C v tr so vi ni i.

Ngoi phn ng trng hp, phn hy, olefin cn tham gia cc phn ng ngng t, ankyl ha vi cc RH naphten hay hyrocacbon thm to ra cc hp cht cao phn t v cui cng l to thnh nha v cc.

5.1.3. S bin i ca RH naphten

RH naphten c bn nhit cao hn so vi parafin c cng s nguyn t cacbon trong mch. Cc bin i c trng ca RH naphten nhit cao l thng xy ra c cphn ng u tin theo th t sau:

Kh nhnh ankyl

Kh hyro to olefin vng v sau tip tc to thnh RH thm

Kh naphten n vng thn hparafin v olefin hay diolefin

Nh vy r rng l cc naphten khi tham gia phn ng phn hy nhit, sn phm ta thnh c c trng no hn so vi parafin, v c xu hng to thnh nhiu cc phn t c trng lng trung bnh, ngha l cho php to nhiu sn phm lng hn so vi nguyn liu l parafin

5.1.4. S bin i ca RH thm

nhit cao, s bin i RH thm xy ra theo quy lut sau:

Kh nhnh ankyl

Cc gc thm ngng t vi nhau, kh hro to thnh gc

mi c phn t lng ln hn v nhiu vng thm hn.

Cui cng pht trin thnh hp cht cao phn t gi l cacboit hay gi l cc. Nh vy cc du m khc vi cacbon nuyn t ch chng l h vng thm c ngng t cao. Cc to ra thng lng ng, bm vo thnh ng phn ng hay thit b trao i nhit,