công nghệ chế biến

7/31/2019 cng ngh ch bin

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BI 5. THIT B CHNG CT

M bi: HD I5

Gii thiu.

Du th v cc sn phm du m l hn hp ng nht ca nhiu cu t.

Mi mt cu t hay mt khong cc cu t c mt ng dng khc nhau. Vic

phn chia cc cu t ny thnh cc phn on ring bit cho cc mc ch s

dng l mt cng vic quan trng trong cng ngh ch bin du kh. phn

chia cc cu t(hay mt khong cc cu t) ra thnh cc sn phm ring bit

v nguyn tc c nhiu gii php cng ngh nh: chng luyn, hp th, trch

ly,... Tuy nhin, phng php chng luyn vn l phng php phn chia hn

hp ng nht kinh t v hiu qu nht cp dng trong lnh vc ch bindu kh.

Qu trnh chng ct trong cng nghip ch bin du kh rt phc tp v c

nhiu c th ring. Nguyn l ca qu trnh chng ct c cp trong

phn chuyn khi ca gio trnh Qu trnh v thit b, tuy nhin cc ti liu

ny mi ch gii thiu nguyn l chung p dng cho cc qu trnh chng ct

n gin, c bit, cha cp n cu to cc thit b chng ct s dng

trong cng nghip ch bin du kh. Trong khun kh ca bi hc ny s gii

thiu nguyn tc chng luyn v cu to ca thit b chng ct s dng trongcng nghip ch bin du kh. Vi mc ch gip hc sinh tip cn gn hn vi

thc t, mt s qu trnh chng ct quan trng cng s c cp ti.

Mc tiu thc hin.

Hc xong bi ny hcvin c nng lc:

- M t c cu to chung thp chng ct trong cng nghip ch bin

du kh

- M t c s cng ngh, cu to thp chng luyn p sut

thng,- M t c s cng ngh, cu to thp chng luyn p sut chn

khng.

- M t c s , cu to thp chng ct trong mt s phn xng

Cracking v mt s phn xng khc nh Reforming, NHT, CCR.

- M t c cc phng thc iu khin cc thng s cng ngh trong

thp chng luyn.

- Nhn bit c cc dng a, thp chng luyn trong thc t.

- Vn hnh c thit b chng luyn trong phng th nghim .

http://www.ebook.edu.vn


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Ni dung chnh:

- Nguyn l hotng, cu to chung ca thp chng luyn trong cng

nghip ch bin du kh;

- Cc dng thp chng luyn dng a v dng m;

- Cu to v nguyn l hotng thp chng ct du th p sut khquyn;

- Cu to v nguyn l hotng thp chng ct chn khng;

- Cu to v nguyn l hotng thp chng ct chnh trong phn xng

cracking;

- Cu to v nguyn l hotng thp chng ct trong mt s cng ngh

quan trng: Reforming, X l Naphtha bng hydro.

- Nguyn l iu khin hotng ca thp chng luyn.

5.1. VAI TR THIT B CHNG CT V I TNG NGHIN CU

5.1.1. Vai tr thit b chng ct trong cng nghip ch bin du kh

Thit b chng ct gi mt vai tr quan trng trong cng nghip ch bin

du kh. Hu ht cc qu trnh phn tch hn hp lng ng nht ra thnh cc

phn on trong cc qu trnh cng ngh u s dng phng php chng ct.

Khi u cho mi qu trnh ch bin du th l qu trnh chng ct du th

p sut kh quyn. Du th khi qua thit b chng ct p sut kh quyn, cc

phn on du m mi c tch ra thnh cc sn phm (Kerosene, phnon Diesel-LGO) hoc sn phm trung gian lm nguyn liu cho cc qu trnh

ch bin tip theo nh cn chng ct, phn on Naphtha, LPG,...

Vi cc qu trnh ch bin quan trng khc (cracking xc tc, reforming, isome

ho v cc qu trnh x l bng hydro), sau khi thc hin qu trnh ch bin ho

hc, hn hp hydrocacbon u phi c a ti thit b chng ct phn

chia thnh cc phn on khc nhau.

5.1.2. i tng nghin cu

Nguyn l chung ca qu trnh chng ct c cp t nhiu tronggio trnh Qu trnh v thit b cng ngh ho, tuy nhin, trong cc chng

trnh ny cha cp n c th qu trnh chng ct cc sn phm du m.

Du m l hn hp ca hng ngn cu t, v vy, qu trnh chng ct du m

v cc phn on du m rt phc tp v c nhng c th ring bit cn phi

c nghin cu, tm hiu pht trin thm ngoi cc kin thc chung v chng

luyn. Mt khc, hc vin c kin thc v l thuyt v thc hnh th cn

phi c hc tp tng qu trnh c th v c nguyn l hotng v cu to

thit b nhm h tr cho vic hnh thnh k nng vn hnh sau kh kt thc



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chng trnh o to. T nhng phn tch trn v mc tiu o to, trong phm

vi ca bi hc ny s tp trung vo nguyn l v cu to thit b c trng trong

cng nghip ch bin du kh.

5.2. NGUYN L QU TRNH CHNG CT DU M

5.2.1. Tnh cht du th c c s cho tnh ton, thit kcng ngh v la chn thit b chng

ct trc ht cn phi hiu c nhng tnh cht c bn ca nguyn liu v

cc thng s c bn ca nguyn liu l c s cho vic tnh ton la chn thit

b. Cc tnh cht ho l l cc tnh chtquan trng phc v cho tnh ton thit b

chng ct, tnh cht ho hc ca du gip cho tnh ton cc qu trnh ch bin

ho hc tip theo.

5.2.1.1. Tnh cht ho l

a. Thnh phn

Du th khng phi l n cht m l hn hp ca hng ngn cc hp

cht khc nhau. Cc hp cht ny ch yu l s kt hp gia hydro v nguyn

t cacbon hnh thnh cc cu t gi l hydrocacbon t dng n gin nh

kh m tan (CH4) n cc dng phc tp nh C85H60. Tnh cht quan trng ca

du th l tng cu t cha trong n c nhit si khc nhau trong cng iu

kin p sut v nh hin tng vt l ny m chng c phn tch ra ring

bit bng phng php chng ct.b. ung cong chng ct

ng cong chng ct l mt trong nhng s liu quan trng ca du th,

qua ng cong chng ct phn nh tnh cht ho l quan trng ca mi loi

du m. ng cong chng ct biu th mi quan h gia nhit v phn

trm th tch (hoc khi lng) du th bay hi (tch lu). ng cong

chng ct l c s quan trng cho thit k thp chng ct phn chia cc cu

t ra cc phn ring bit. ng cong chng ct c thc hin trong phng

th nghim bng cch tin hnh gia nhit cho mt lng du th cha trong ccchu nhit (hoc thit b chng ct chuyn dng) cc nhit khc nhau. ng

vi mi nhit tin hnh o tng lng cht lng bay hi. T s liu thu

c tin hnh v ng cong quan h gia nhit v th tch cht lng

bay hi tch lu nhit tng ng. S minh haqu trnh th nghim v

xy dng ngcong chng ct c m t trong hnh v H-5.1 v H-5.2.

c. Phn on

Nh bit, du m gm rt nhiu cc hp cht ho hc c tnh cht l

ho khc nhau. Mt nhm cc hp cht phc v cho mt mc ch s dng no



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c gi l mt phn on (hay cn gil khong ct). Cc phn on hay

khong ct l tn gi chung ca tt c cc cu t c nhit si nm gia

khong hai gi tr nhit no . Ccgi tr nhit ny c gi l im ct.

Cc phn on in hnh cha trong du th v nhit khong ct nh trong

bng 5-1 di y.Bng 5.1.Cc phn on in hnh ca du th

TT Phn onKhongnhit

(0C)

1 Bu tan v cc cu t nh hn (C4-) < 35

2 Naphtha nh C5+ - 80

3 Naphtha nng 80170

4 Kerosene 1702305 Diesel (Gas Oil) 230370

6 Cnchng ct > 370

Ty theo tng loi du m thnh phn ca cc phn on khc nhau. Du

th nh c cc phn on Naphtha nh, Naphtha nng v Kerosene nhiu hn

cn du th nng th c cc phn on Diesel v cn nhiu hn. Cc cu t c

khi lng cng nng th cng c nhit si cng cao. Trc y, cc Nh

my lc du thng ch bin du nh v em li li nhun cao hn u t t v

bn thn du th cha nhiu cu t c gi tr kinh t cao. Tuy nhin, trongnhng nm gn y, ngun du th gim st v gi du ngy cng tng cao th

ch bin du nng li c nhiu u th do gi du nng thp hn tng i

nhiu so vi du nh. iu ny t ra thch thc ln cho cc Nh my lc du

xy dng trc y trong cuc cnh tranh.

d. Hm lng lu hunh

Hm lng lu hunh trong du th rt khc nhau gia cc loi du. Hm

lng lu hunh trong du th l mt trong tnh cht quan trng quyt nh gi

tr du th. Do lu hunh l tp cht c hi nn hm lng lu hunh nhhng nhiu n cht lng du th. Hm lng lu hunh trong du th ln

lm gim gi tr ca du do phi u t cho qu trnh ch bin nhiu hn (ch

yu l cc phn xng x l) v vn bo v mi trng gp phi nhiu kh

khn khi m bo hm lng cc hp cht lu hunh c hi trong kh thi.

Lu hunh cha trong du th khng phi dng n cht m dng cc hp

cht (nh H2S, Mercaptans, COS,...). Phng php x l cc tp cht ny

c trnh by bi 4 ca gio trnh ny. Cn c vo hm lng lu hunh

trong du th m ngi ta chia du th thnh loi du ngt (Sweet Crude), du



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chua (Sour Crude) v du trung gian gia ngt v chua. Du ngt l cc du c

hm lng lu hunh khng ln hn 0,5% khi lng, cn du chua l du

cha hm lng lu hunh khng nh hn 2,5% khi lng. Du th c hm

lng lu hunh nm trong khong trn l du trung gian (gia ngt v chua).

Trong cc nh my ch bin du kh, khi tng lng lu hunh thi ra mitrng vt mc cho php (c bit l khi ch bin du chua) th kh chua

(cha hp cht lu hunh nh H2S, SO2) s c a ti phn xng thu hi

lu hunh lm sch kh thi v thu hi lu hunh nguyn cht nh l mt

sn phm ph.

Hnh H-5.1S th nghim xy dng ng cong chng ct

Hnh H-5.2.ng cong chng ct im si thc

5.2.1.2. Thnh phn ho hc v phn loi du m

Nh trnh by, du m l hn hp phc tp cu thnh t hng ngn

cc cu t khc nhau, mi mt loi du c thnh phn ha hc v tnh cht ha

l khc nhau. Tuy nhin, v bn cht, cc loi du u c c im chung l



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thnh phn hydrocacbon chim ch yu (khong 60-90% tng khi lng),

phn cn li l cc hp cht cha lu hunh, ni -t, -xy, cc cht nha,

asphanten v cc phc c kim.

a. Thnh phn Hydrocacbon

Hydrocacbons l phn chnh ca du m. Cc hydrocacbons ny li baogm nhiu nhm khc nhau nh: Parafins, Naphthens, Aromactics (trong du

m khng cha Olefins, Olefins hnh thnh trong qu trnh ch bin)

Nhm Parafins

Parafins l loi hydrocacbon ph bin nht trong du m. Thnh phn

parafins c nhn dng theo quy lut: trong phn t hydrocacbon, cc nguyn

t cacbon ni vi nhau bng lin kt n, cc lin kt khc c bo ha bng

nguyn t hydro. Cng thc chung cho cc cu t thnh phn nhm parafins l

CnH2n+2. Parafin n gin nht l Metan (CH4), tip theo l hng lot cc hp

cht nh ethan, propane, butane (iso-butane v mch thng), pentane,... Khi

nguyn t cacbon trong phn t hydrocacbon ln hn ba th mt s

hydrocacbon c cc lin kt khc nhau phn t khc nhau. Cc nguyn t

cacbon khng ch lin kt vi nhau dng mch thng m cn lin kt thnh

cc mch nhnh n hoc nhnh kp to ra cc dng ng phn c tnh cht

nhiu khi khc xa hydrocacbon khc cng loi. V d, s octan thc nghim

(MON) ca n-octane ch l 17 trong khi s octane ca iso-octane l 100. Slng cacbon trong phn t cng nhiu th kh nng to ra cc dng ng

phn cng ln. V d butane c hai ng phn, pentane c ba ng phn,

octane c ti mi by cu trc ng phn, khi s nguyn t cacbon tng ln

18 (cetane) th s ng phn ln ti 60533. Trong du th c phn t parafins

cha ti 70 nguyn t cacbon vi s ng phn rt cao.

Nhm Naphthenes (Cycloparafins)

Cc parafins mch vng trong tt c cc lin kt cn li ca nguyn t

cc bon u c bo ho bng nguyn t hydro gi l naphthene. C rtnhiu dng naphthene tn ti trong du m, tuy nhin, cc naphthene c khi

lng phn t thp (nh cyclopentane, cyclohexane) thng thng khng

c xem nh l nhng cu t ring bit, trong thc t nhm cu t ny c

phn loi bng khong nhit si. Mt s dng cu trc phn t ca

Naphthenes in hnh c trnh by di y:



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Cyclopentane Methyl-cyclopetane Dimethylcyclopentane

Cyclohexane 1,2 Dimethylcyclohexane Methyl-cyclohexane

Decalin

Nhm Aromactics

Nhm cc hp cht aromantics c tnh cht l ho khc rt xa cc hp

cht parafins v naphthenes. Cc hydrocacbon dng ny cha mt mch vng

benzene khng bo ho nhng rt n nh. Tuy cc lin kt ca cc nguyn tcacbon khng bo ho hon ton nhng cc hp cht aromactic lun c tnh

cht nh l mt hp cht bo ho cc lin kt. Mt s dng in hnh ca

aromactic thng gp trong du c trnh by di y:

Benzene Toluene Ethylbenzene Ortho-xylene

Para-xylene Meta-xylene Naphthalene

Nhm Olefins



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Nh cp phn trn, v nguyn tc, olefins khng tn ti trong du

th, tuy nhin, trong qu trnh ch bin (c bit l qu trnh cracking) to ra

olefins. Cc hp cht olefins c cu trc tng t nh cc hp cht parafins.

Tuy nhin, trong phn t ca hp cht olefins t nht c hai nguyn t cacbon

c lin kt i. Cng thc ho hc chung ca nhm hp cht ny l CnH2n.Trong ch bin du kh, nhm cc cht olefins l nguyn liu quan trng cho

ha du.

b. Thnh phn phi hydrocacbon

Ngoi cc hp cht hydrocacbon, trong du m cn cha cc hp cht

khc (cn gi l cc thnh phn phi hydrocacbon). Cc thnh phn phi

hydrpcacbon ch yu l cc hp cht ca lu hunh, ni-t, cc cht cha -xy,

kim loi v cc cht nha, asphanten.

Cc hp cht lu hunh

Ngoi hydrocacbon, trong tng lng cc cht phi hydrocacbon th hp

cht lu hunh thng cha mt t l ln nht (c khi ti trn 2% khi lng).

Cc hp cht lu hunh chnh cha trong du m v cc sn phm l H2S,

Mercaptan (R-S-H), Sulfure (R-S-R), Disulfure (R-S-S-R) v Thiophen (lu

hunh trong mch vng). Mt s dng hp cht Thiophen c cu trc phn t

nh di y:

Lu hunh c mt trong du th cng nhiu cng lm du xu i do gy

kh khn cho qu trnh ch bin v bo v mi trng.

Cc cht cha ni-t

Cc hp cht cha ni-t thng c rt t trong du m v cc sn phm

du m. Hm lng ni-t c trong du cao l iu khng mong mun i vicc nh ch bin. Cc hp cht hu c ca ni-t gy ng c xc tc ca cc

qu trnh ch bin du kh rt mnh v gy ra hin tng n mn my mc,

thit b. Khi hm lng ni-t trong du cao hn 0,25% khi lng th cn phi

c yu cu x l c bit trc khi ch bin. Cc dng hp cht ca ni -t

thng gp trong du l:



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Cc cht cha -xy

Cc hp cht cha -xy tn ti trong du th thng di dng axit,

phenol, xeton, ete, este... Trong s cc hp cht cha -xy th phenol v axit l

ng ch hn c do cc hp cht ny nh hng n mt s qu trnh cng

ngh cng nh sc kho, an ton mi trng. Cc hp cht ny thng tn ti

trong cc phn on c nhit si trung bnh (Kerosene) v cao (Gas Oil).Dng axit thng gp v cn x l l axit naphthenic (R-COOH). Mt s dng

phenol thng gp trong du m v cc sn phm du l cc loi di y:

Cc cht nha v asphantene

Nha v asphantene l hp cht ca cc nguyn t C, H, O, N, S c phnt lng rt ln. C nha v asphantene u c c im chung l khng tan

trong nc c t trng ln hn 1. V cu trc phn t, nha v asphantene u

c cu trc h vng ngng t cao. Cc hp cht ny nm tp trung cc phn

on nng nh cn chng ct kh quyn, cn chng ct chn khng. Tuy

nhin, gia cn v nha vn c nhng c im ring. Nha thng c phn

t lng thp hn so vi asphantene. Nha cha trong du m d b xy ho

chuyn thnh dng asphantene, chnh v vy m asphantene c phn t

lng cao hn. C nha v asphanten c trong du th nhiu u khng tt dohiu sut thu hi sn phmnh (c gi tr cao) thp, qu trnh ch bin phi u

t nhiu hn. S c mt ca cc hp cht ny cn gy ng c xc tc nh

hng n hiu sut, cht lng sn phm ca qu trnh ch bin. Mc du

vy, nu trong du c hm lng nha v asphantene caoli l nguyn liu tt

sn xut nha ng.

Cc dng hp cht khc



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Ngoi cc hp cht phi hydrocacbon nu trn, trong du cn cha mt

lng nc nht nh. Nc cha trong du th vn d tn ti ngay trong du

th t trong qu trnh hnh thnh du v b nhim bn trong qu trnh khai thc.

Nc trong du th thng tn ti di dng nh tng. v ho tan cc mui

hu c v v c lm nhim bn du. V vy, trc khi ch bin, du th phic tch mui v nc (vn ny s c cp trong phn chng ct du

th p sut kh quyn).

c. Phn loi du th

C nhiu phng php phn loi du th nh cn c vo thnh phn

ho hc, cn c vo tnh cht vt l.

Phn loi theo thnh phn ho hc

Vic phn loi du m theo thnh phn ho hc cng ty thuc vo cc c

quan nghin cu du th a ra cc tiu chun phn loi khc nhau (Vin du

Hoa k-API, Vin du m Php- IFP, Vin du m Nga,...). Tuy nhin, im

chung ca phng php phn loi ny l cn c vo thnh phn ho hc ca

du th l parafins, naphthenic, aromactic chia ra cc loi du khc nhau.

Phn loi theo bn cht vt l

Phng php phn chia du th theo bn cht vt l l da trn t trng

ring ca du th, chia du thnh cc du: nng, du trung bnh v du nh.

Thng thng du nh c t trng 0,884 c coi l du nng. Trong

thc t tnh ton cng ngh cng nh giao dch ngi ta thng s dng n

v o 0API (theo tiu chun ca vin du mHoa k) thay cho t trng. Quan

h gia t trng ring v 0API c biu th qua biu thc di y:

5,1315,141

dAPI

o

Trong d l t trng ring ca du iu kin tiu chun.

5.2.2. Nguyn l5.2.2.1.t vn

Du th khng phi l n cht, hay hn hp ca mt vi hp cht ho

hc m l hn hp ca hng ngn hn hp ho hc, v vy, vic phn chia cc

hp cht ho hc ny hay mt khong cc hp cht ny (mt phn on) bng

phng php chng ct l rt phc tp. Nguyn l ca qu trnh chng ct

cng c cp gio trnh khc. Tuy nhin, trong cc gio trnh ny mi

ch cp n nguyn l chng ct hai cu t l chnh. Chnh v vy, cn thit

phi cp nguyn l chng ct trong cng nghip ch bin du do du th v



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phn on cnhng c im ring nh gm rt nhiu cu t, d chy n. Do

nhng c im ring ny m cu to ca cc thp chng ct cng c nhiu

im khc bit so vi cc thp chng ct s dng trong cc ngnh cng nghip

khc.

5.2.2.2. Cc khi nim hiu c nguyn l qu trnh chng ct du m v cc sn phm du

cn phi hiu mt s khi nim c nh ngha ring trong cng ngh lc ho

du. y cng l cc thng s cng ngh c bn cn c xc nh trong qu

trnh thit k cc thit b chng ct.

a. im ct

i vi cc nh cng ngh v thit k thit b chng ct th im ct l mt

trong nhng thng s cng ngh quan trng. Cc nhit m ti cc sn

phm chng ct c phn chia ra thnh cc phn on khc nhau gi l cc

im ct. Vi mi phn on (hay cn gi l khong ct), gi tr nhit m ti

sn phm (phn on) bt u si gi l im si u (Initial Boiling Point-

IBP). Nhit m ti ton b (100%) sn phm bay hi gi l im si cui

(End Point-EP).

V vy, mi mt sn phm (phn on hay khong ct) c hai im ct l

im si u v im si cui. Nh vy,vi hai phn on k tip nhau ti im

ct ca hai phn on ny, im si cui ca phn on nh hn cng chnh lim si u ca phn on nng hn. V d vi hai phn on Naphtha v

Kerosene, im si cui ca phn on Naphtha cng l im si u ca phn

on Kerosene. Tuy nhin, trong thc t, hiu qu qu trnh phn tch khng

phi lc no cng t ng theo l thuyt, v vy m im si cui ca phn

on nh hn v im si u ca phn on nng k tip c th khng trng

nhau. V d nh hnh H-5.3

Khong chng ln gia hai phn on phn nh hiu qu ca qu trnh

chng ct. y l mt thng s quan trng m cc nh thit k v ch to phibo m (guarantee) cho ngi s dng. minh ha r hn v khong chng

ln nhit si u v nhit si cui gia cc phn on chng ct ngi ta

xy dng ng cng biu th mi quan h gia nhit si v phn th tch

phn on bay hi ti nhit (khng phi tng th tch phn bay hi tch ly).

Cc ng cng ny vi khong chng ln c minh ha hnh H-5.4. T

th minh ha ny ta thy r c khong chng ln nhit im si u v si

cui gia cc phn on. Khong chng ln ny cn c kim sot cht ch

trong thit k thit b chng ct m bo cht lng ca cc phn on.



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Hnh H-5.3 Khong chng ln ng cong chng ct hai phn on k tip

nhau

Hnh H-5.4 Khong chng ln im si u v im si cui hai phn on ktip nhau

b. Xc nh im ct

Xc nh im ct ca cc phn on l vic lm ht sc quan trng ca

nh thit k. im ct c nh hng ln ti hiu sut thu hi v cht lng ca

cc phn on. Ty theo tnh cht ca du, mc ch ca nh my (cc sn

phm cn sn xut, cc loi sn phm cn u tin, cht lng sn phm yu

cu) m xc nh im ct cc phn on chng ct cho ph hp. V d, vic

chn im ct gia hai phn on Naphtha nng v Naphtha nh, nu chn



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nhit im ct l 700C cho php thu hi c nhiu phn on Naphtha

nng hn, do vy cho php tng c s Octan ca xng ton nh my (do

Naphtha nng l nguyn liu cho qu trnh reforming). Tuy nhin, vic chn

nhit ct thp th trong Naphtha nng cha nhiu tin t to th nh

Benzene trong qu trnh reforming. Nu nh Nh my c sn xut BTX(Benzen, Toluen, Xylene) th la chn ny l ph hp, song nu nh mc ch

ca nh my ch sn xut nhin liu l chnh m li khng c u t phn

xng ng phn ha Naphtha nh (Isome ha) th hm lng benzene trong

xng thnh phm thng cao. Trong trng hp ny, gim hm lng

benzene trong xng ngi ta thng tng nhit im ct gia hai phn on

Naphtha nng v Naphtha nh ln khng thp hn 800C.

Ngoi nhng nh hng su xa ti cc qu trnh ch bin v cht lng

sn phm cui cng nh v d trn, vic thay i nhit im ct nh hng

trc tip ngay n cht lng ca tng phn on nh t trng, nhit im

ng c,... Chnh v vy, xc nh nhit im ct l vic lm ht sc quan

trng trong qu trnh thit k nh my lc ha du i t ngun du th. Vic xc

nh nhit im ct phi c nh gi mt cch tng th v kinh t k thut

v mi trng.

Hnh H-5.5 Nguyn l phn tch cc cu t c nhit si khc nhau

5.2.2.3. Nguyn l qu trnh chng ct du

a.Nguyn l

Nguyn l chung



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Phn tch cc cu t trong du th cng da trn nguyn tc s khc

nhau v nhit si ca cc cu t ny trong cng iu kin. Tuy nhin, c mt

iu may mn l a s cc sn phm du kh cng khng phi l n cht m

l tp hp ca nhiu cu t c nhit si nm trong khong nht nh (mt

phn on), v vy, khng phi phn tch hng ngn cc cu t thnh cc snphm ring bit (mt iu khng kh thi trong thct) m ch cn tch du th

thnh mt s phn on nht nh. Qu trnh chng ct tch cc phn on

c thc hin trong cc thp chng ct. Qu trnh phn tch c thc hin

cc a (thp a) hay b mt tip xc (thp m). Cc cu t nng c nhit

chuyn pha (bay hi hay ngng t) cao hn so vi cc cu t nh c xu hng

d b ngng t hn, khi ngng t, cc cu t ny gii phng ra mt lng nhit

lm cc cu t nh hn bay hi. Qu trnh c tip din nh vy lm cho cc

cu t nh hn s tng dn pha phn trn ca thp. Hnh H -5.5 minh ha

qu trnh phn tch cc cu t c nhit si khc nhau qua hin tng trao

i nhit gia cc cu t trong thp chng ct.

Tuy nhin, khc vi qu trnh chng ct hn hp hai cu t, qu trnh

chng ct du m v cc sn phm trung gian bao gm nhiu cu t v phn

on nn sn phm qu trnh chng ct s c ly ra khng ch nh v y

thp m cn c ly ra mt s v tr thch hp. Vn ny s c cp

su hn v nguyn l v cu to thp chng ct.S nguyn l chng ct trong cng nghip ch bin du kh

Trong cng nghip ch bin du kh, qu trnh chng ct u l qu trnh

lin tc. Thit b chng ct l cc thp chng ct (ct chng ct). S nguyn

l hotng chung ca cc thp chng ct s dng trong cng nghip ch bin

c n gin ho nh minh ha trong hnh H-5.6. Theo s chng ct

ny, sn phm thu c khng ch l sn phm nh v sn phm y nh cc

qu trnh chng ct thng thng m cn c ly ra gia thn t hp. Cc

sn phm ly ra thn thp cc a c cu to c bit. thu hi c chtlng sn phm ph hp, hn hp sau khi ly ra thn c a vo mt

thp sc ph tch phn hydrocacbon c khong nhit si nm ngoi gii

hn sn phm nh tch. Ty theo tnh cht nguyn liu, ng dng c th m

ngi ta thit k cc a thu hi cc sn phm gia thp.



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Hnh H-5.6 Nguyn l chng ct trong ch du kh

Qu trnh hotng ca thp c th tm tt nh sau: Nguyn liu trc

khi a vo thp c nng ti nhit thch hp nh h thng thit b trao i

nhit v l t. Ti a tip liu cc cu t c nhit si thp s bay hi v

ngng t cc a pha trn thp. Phn cc cu t nng hn, c nhit si

cao hn s chy xung phn chng cathp (stripping section). phn tch

cc cu t nh cn cha trong phn nng, y thp thng lp t mt thitb gia nhit trc tip hay gin tip ty thuc vo ng dng c th.

iu khin nhit ca thp, dc theo thn thp ngi ta b tr cc

bm tun hon ly pha lng t trong thp ra lm ngui khi cn thit,

nhm mc ch tch cc phn on nm trong cc khong nhit si ph hp

vi im ct thit k. Sn phm nh sau khi ngng t c hi lu mt phn

tr li thp nhm iu chnhhotng ca thp ph hp. Cc sn phm ly ra

t mt thp ny c th tip tc c a sang thp khc phn tch tip thnh

cc phn on nh hn hoc tch trit cc tp cht.



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b. Mt s nguyn tc c bn trong chng ct du m

Vic thit k, vn hnh thit b chng ct s dng trong cng nghip ch

bin du kh mc d khng cn l bn quyn na, tuy nhin, vn cn l nhng

cng vic kh khn. Mt s nguyn tc c bn cn c lu trong thit k v

vn hnh thit b chng ct c tm tt nh sau:- p sut nh hng ti nhit si ca cc cu t, p sut cng cao

nhit si ca cc cu t cng cao.

- Trong cng iu kin cng ngh nh nhau, nu p sut thp tng ln th

cc sn phm ca qu trnh chng ct s nh hn.

- Nu nhit nguyn liu vo qu thp th lng cu t bay hi a

tip liu s thp v phn khng bay hi s chy xung phn chng ca

thp.

- Nu nhit y thp qu thp, sn phm y s nh v nhiu hn.

- Nu nhit nh thp qu cao th sn phm nh s cng nng hn v

do vy lng sn phm cng nhiu.

- Nhit du nng bay hi cao hn so vi du nh.

- Hi do h thng gia nhit y ng vai tr quan trng trong vic sc cc

cu t nh cha trong pha lng cc a bay hi. Gim nhit gia

nhit y s lm gim lng hi trong thp v gim nhit ca thp.

- Tng nhit lng thit b gia nhit y s lm tng lu lng hi trongthp v tng nhit cc a chng ct. Kt qu l cc cu t trn

cc a s nng hn.

- Tng lng hi lu s lm tng lng cht lng trong cc a. Kt qu

l nhit nh thp s gim i, sn phm nh s nh hn. Tuy nhin,

nh hng ca dng hi lu chm hn.

Trong cc thit k thp chng ct s dng trong ch bin du kh hin nay,

iu khin nhit ca cc a v do iu khin c cht lng sn

phm chng ct ngi ta lp t thm cc h thng bm tun hon. Cc bmny ly cht lng t trong thp ra ngoi iu chnh nhit ri a quay tr

li thp. Trong mt s thit k mi, phng php truyn thng dng dng hi

lu iu chnh nhit nh thp khng cn c s dng trong vn hnh

bnh thng m thay vo l s dng phng php bm tun hon (ng

hi lu ch c s dng trong giai on khi ng thit b).

5.3. CU TO V NGUYN L HOT NG THIT B CHNG CT

Thit bchng ct s dng trong cng nghip ch bin du kh l cc thp

chng ct. Trong cng nghip ch bin, hu nh khng s dng cc qu trnh



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chng ct n gin hay chng gin on (cc qu trnh chng ct ny c

gii thiu gio trnh Qu trnh v thit b cng ngh ho). Trong khun kh

ca bi hc ny ch gii thiu cu to v nguyn l hotng ca thp chng

ct (ct chng ct) s dng trong ch bin du kh.

5.3.1. Phn loiPhn chia dng thit b chng ct cn c ch yu vo cu to chi tit b n

trong ca thp chng ct. V c bn, vic phn chia thp da trn cch thc,

cu to ca b phn to b mt chuyn khi. Thp chng ct c chia thnh

cc loi sau:

- Thp chng ct kiu a;

- Thp chng ct kiu m.

Ty theo cu to c th m cc dng ny li chia thnh nhiu dng khc

nhau nh thp a chp, thp a li, thp m c cu trc ng nht, thp

m c cu trc khng ng nht. Cu to v nguyn l hotng c th ca

cc loi thp ny s c cp cc phn di y ca bi hc ny.

5.3.2. Cu to thp chng ct

5.3.2.1. Thp a

a. Cu to v nguyn l hotng chung

Cu to chung

Thp chng ct dng a l mt ct hnh tr thng ng bn trong lp cca trao i cht v trao i nhit. Mi a l mt bc chuyn khi thc t. C

nhiu dng thp a nhng tt c c c im chung l qu trnh chuyn khi

c thc hin trn cc a lp trong thp. Cu to chung ca thp chng ct

kiu a vi cc dng a khc nhau c minh ha trong hnh H-5.7. Thp

chng ct ng v mt cng ngh c chia lm hai phn: on chng v

on luyn. on chng tnh t a tip liu ti y thp. on luyn t a tip

liu ti a trn cng. ng v mt c kh, thp chng ct bao gm cc b

phn chnh: V thp, a chng ct, cc ng chy truyn.Nguyn l hotng

Nguyn tc hotng chung ca thp a l to ra trn b mt a mt lp

cht lng cho pha hi i t pha di ln. Khi pha hi v pha lng tip xc

nhau trn a cc qu trnh trao i nhit v trao i cht din ra. Cc cu t d

bay hi hn s tch ra khi pha lng chuyn vo pha hi trn b mt ca a,

cn cc cu t c nhit si cao hn s ngng t li hoc gi nguyn trng

thi lng v chy xung a pha di (theo ng chy truyn hay qua cc l trn

a ty thuc vo kt cu).



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Hnh H-5.7- Cu to chung thip chng ct dng a (mt ct ngang)

Trn cc a, ngi ta c cc l v mi l ny c lp mt chi tit gi l

chp. Mc ch ca chi tit ny l to ra cc bong bng hi i xuyn qua lp

cht lng pha trn ca a.Vic to cc bt bong bng i qua lp cht lng

l mt giai on quan trng trong qu trnh trao i nhit v chuyn khi gia

cc pha v gia cc cu t. Trong qu trnh chuyn ng, pha kh trong bong

bng c nhit cao s truyn nhit cho pha lng qua b mt phn chia pha

(mt ca cc bong bng). Kt qu l nhit ca bong bng s gim i mt

cht v do mt s hydrocacbon pha hi trong bong bng s ngng t

chuyn t trng thi hi sang trng thi lng. Trong khi mt s hydrocacbon

trong pha hi ngng t th mt s hydrocacbon nh cha trong pha lng li



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chuyn t trng thi lng sang trng thi hi. Hi hydrocacbon sau khi i qua

lp cht lng trn mt a, mt phn hydrocacbon nng s b ri li trong cht

lng v phn cn li di chuyn ln a pha trn. Qu trnh c nh vy tip din

v pha hi c thnh phn hydrocacbon ngy cng nh i cho ti a cui cng

trn nh thp ch cn li cc hydrocacbon rt nh. Phn hydrocacbon ny sc ngng t thit b ngng t pha ngoi thp v c hi lu mt phn

tr li thp. Do qu trnh ngng t ca hi trn mt a tch t dn li ngi ta

phi thit k mt ng ng dn cht lng xung a pha di. ng ny

c gi l ng chy truyn.

Trong qu trnh lun chuyn gia pha lng v pha hi, mts cu t bay

hi t mt a pha di ln trn ri li ngng t thnh pha lng ri chy

ngc li qua ng chy truyn qua mt s a. Vng tun hon ny c th lp

li mt vi ln v nh cc phn on hydrocacbon c tch ra. tch

cc phn on ra gia thn thp ngi ta thit k mt s a c bit a

cc phn on ny ra ngoi thp. Tng lng lng rt ra thn thp, y v

nh thp phi cn bng vi lng nguyn liu a vo m bo thp lm

vic n nh. Nguyn l qu trnh phn tch cc cu t trong thp c minh

ha trong hnh H-5.8.

b. Cu to mt s b phn

Trong cng iu kin nh nhau, hiu qu lm vic ca thp chng ct phthuc ch yu vo kt cu v nguyn tc hotng ca cc chi tit bn trong:

chp to bong bng, kt cu a, ng chy truyn,... Cu to cc b phn bn

trong ca thp c minh habng hnh nh trong hnh H-5.9.

Hnh H-5.8- Nguyn l qu trnh chuyn khi trong thp



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Hnh H-5.9- Cu to cc chi tit bn trong thp

Cu to ca chi tit mt s b phn ny s c trnh by di y.Cc dng a v cu to

Trong thp dng a, theo cu to ca b phn to bong bng m thp

chng ct dng a li c phn chia ra thnh nhiu dng thp khc nhau

nh: thp a l, thp a chp, thp a van,... Cc dng thp truyn thng

c s dng trc y l a chp. Trong nhng nm gn y do yu cu v

hiu qu qu trnh chng ct v gim gi thnh ch to, nhiu dng a mi

c nghin cu v pht trin a vo s dng nh cc dng a van, a

Ballast, Flexible,...a chp dn c thay th bng cc loi a c cu to n gin, nh

hn v tng ng l r tin hn nh cc dng a van, a l,...Tuy nhin, mi

loi a u c nhng u, nhc im nht nh. Khng c loi a no hon

ton tt hoc hon ton xu. Mt khc mi mt dng a c ng dng i vi

mt loi nguyn liu nht nh. V d a chp mc d c cu to phc tp gi

thnh cao, hiu qu qu trnh chuyn khi khng phi cao nht nhng c th

dng c hu ht trong cc ng dng. Loi a van cu to n gin hiu qu

cao, tuy nhin, do c b phn chuyn ng, v vy i lc xy ra hin tng kt

lm nh hng n hiu qu hotng ca thp. Thp a l c cu to n

gin (vi kch thc l trong khong t 3mm-15mm), tuy nhin, loi thp ny

vn xy ra hin tng pha lng chy trc tip qua cc l trn a lm tc nghn

dng hi hoc lm gim lu lng hi t di i ln v do vy lm gim hiu

qu hot ng ca thp. Trong thc t, vic la chn loi a no cho thp

chng ct ph thuc vo nhiu yu t nh bn cht ca nguyn liu ch bin,

hiu qu phn tch v yu cu v tn tht p sut trong thp.



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a chp

a chp l loi a truyn thng s dng rng ri trong cng nghip ch

bin du kh cng nh trong cc ngnh cng nghip khc. a chp c u im

l khong ng dng rng ri t chng ct du th ti cc phn on khc. a

chp c kh nng hot ng n nh vi cc thay i ca lu lng dnglng/hi trong thp. Tuy nhin, dng a ny cu to phc tp nhiu chi tit

nng n do ko theo gi thnh cao. Cu to in hnh v nguyn l hot

ng ca a chp c minh hatrong hnh v H-5.10. Vi cu to ny, nu

tng din tch b mt tip xc pha lng-hi th cng phi tng tit din ca ng

chy truyn mt cch tng ng m bo cn bng lng lng, hi vo ra,

bay hi-ngng t. Trong nhng nm gn y, cc nh bn quyn v cc dng

a chng ct c nhiu ci tin v kt cu ca a chp tuy nhin dng a

ny vn t cho vi cc dng a khc. Chnh v vy m trong cng nghip ch

bin du kh, cc qu trnh yu cu c hiu sut qu qu trnh cao vi chi ph

u t hp l th cc dng a khc ngy cng c s dng nhiu thay th

a chp.

Hnh H-5.10- Cu to thp a chp

a chp l dng a tng i thng dng v cng c gii thiu

gio trnh khc, v vy, trong khun kh ca gio trnh ny khng i su thm

chi tit cu to ca chp.

a vana van l dng a chng ct tng t nh loi a chp, tuy nhin, ti

cc v tr lp chp c thay th bng chi tit c th ng m l hi cc mc

khc nhau. C rt nhiu loi van a, tuy nhin, nguyn l hotng chung

ca loi van a l cc van s ng m mt v tr ty thuc vo lu lng ca

dng hi t di ln. Nh nguyn tc hotng ny m thp hot ng tng

i n nh hn ch hin tng lng ko theo dng hi do tc qu ln hoc

hin tng sc thp. Nguyn l hotng v cu to chung in hnh ca mt

van a c minh ha trong hnh H-5.11 v cu to ca mt vi dng a van



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in hnh khcc m t trong hnh H-5.12. Mt s c im chnh ca a

van:

- C kh nng hotng khong rng ch hotng ca thp. Loi

a ny c bit c nh gi cao nh kh nng duy tr c hiu qu

lm vic ngay c khi hot ng di cng sut thit k (trong chbin du kh vic m bo hotng mc di cng sut l yu cu

bt buc m bo hot ng linh ng ca nh my, c bit l

trong giai on khi ng v khi gp s c).

- Lp cht lng pha trn a n nh, vy hn ch hin tng ko theo

lng ln a pha trn lm nh hng n hiu qu qu trnh phn tch.

- Nng lng dng hi i qua van c s dng mt cch c hiu qu

ci thin qu trnh tip xc lng-hi.

- Tr lc cc b do cc van gy ra cho dng chy pha lng trn a

khng qu ln (thm ch khng cn ng k khi pha hi ch mc 20%

thit k), v vy, m chnh b mt cht lng gia cc phn ca a

c gim thiu. Nh c im ny m hiu qu lm vic ca cc vng

trong a ng u.

- D ch bin bt c nguyn liu no th ton b a c s dng do

vy ch mt phn nh vng cht c th xut hin.

- Kiu a ny c kt cu vng chc, nh v khng t.- Thit k v vn hnh loi a ny n gin, v vy, sai st xy ra khng

ln hoc nhng nh hng t cc sai st ny khng qu nghim trng.

Hnh H-5.11A- Van trng thi ng Hnh H-5.11B- Van trng thi m mtphn

Hnh H-5.11C- Van trng thi m hon ton



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Hnh H-5.12- Hnh dng mt s dng a van

Hnh H-5.13- Hnh nh kt cu tng th ca a van lp t trong thp chng

ct

Dng a c bit (Ballast v Flexi)

Kt cu ca mt s dng a ny nh m t trong hnh H-5.14. V nguyn

tc, cc dng a ny l dng ci tin van a. m ca van dng ny ciu chnh t ng ph hp vi tc dng kh v hi trong thp. nghing

ca lp cht lng chy trn a cng thp hn so vi van a, v vy m c th

cho php tng lu lng dng kh v hi trong thp ti 20-30%. Vi kt cu

c bit, a chng luyn dng ny cho php thp hotng rt n nh, thm

ch lu lng dng kh/hi thp. Mt s c im chnh ca dng a ny l:

- Tn tht p sut l rt nh, do vy, tng tn tht p sut trong thp nh

ph hp viqu trnh chng ct chn khng.

- C th hotng thch hp vi cng sut cao hn nhiu so vi a van;- C kh nng phn tch cc cu t tt nh to iu kin chuyn khi tt

v s hotng n nh.

- Hiu qu hot ng cao cng sut thp m bo gim thiu ti a

lng sn phm khng t cht lng trong giai on khi ng thp.

- linh ng cao cho php hotng trong khong rng cng sut ch

bin vi tiu th nng lng mc ti thiu.

- Hotng vi hiu sut cao ngay c iu kin 5-10% di gii hn

thp bt u xy ra hin tng sc, nh vy m c th tng cng sut



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hiu dng ca thp, cho php tn dng mt cch hiu qu thp chng

ct v cc thit b ph.

- Hiu sut hotng cao iu kin cng sut trung bnh cho php ci

thin c cht lngsn phm, gim c t l hi lu v do cho

php gim c nng lng, ph tr tiu th hoc gim c s lnga trong thp.

- Thit k c kh ca cc phn tai, chn mc (b phn nh hng cho b

phn chuyn ng ca van) gn nh loi b hon ton hin tng kt

ca b phn chuyn ng. Thi gian ngng thp gim ng k do kh

nng thu hi cht lng nhanh.

Hnh H-5.13 Cu to mt s dng a ballast v flexi

Hnh H-5.14. Hnh nh kt cu tng th a ballast lp t trong thp chng ct

ng chytruynv cc s kt cu a chng

Ngoi kiu kt cu b phn to b mt tip xc pha (cc chp, van to

bong bng), s b tr mt a chng c nh hng nhiu ti hiu qu hot

ng ca thp. S b tr ca thp ch yu ph thuc vo cch thc b tr

cc dng chy trn b mt ca cc a. Cch thc b tr cc dng chy trn a

c lin quan n s lng cc ng chy truyn. Trong thp chng ct, ng

chy tryn c nhim v a cht lng a pha trn xung a pha di v



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khng cho php pha hi i qua ng ny. Vic b tr cc ng chy truyn c

ngha quan trng i vi hotng ca thp mc d khng phi l mt b phn

to ra tip xc pha. Vic b tr s ng chy truyn, kt cu ng chy truyn nh

hng ti s dng chy trn a chng, din tch b mt hiu dng ca a do

nh hng gin tip ti hiu sut v kch thc ca thp chng ct.S b tr a chng ct v ng chytruyn

Trong thc t, ty thuc vo tnh cht nguyn liu ch bin, cng sut ch

bin m kch thc ca thp s c thit k khc nhau p ng yu cu.

Vi cc thp chng ct c kch thc nh th c th ch c mt dng chy ca

cht lng trn mt a. Tuy nhin, vi cc thp chng ct c kch thc ln th

vic b tr dng chy trn mt a l vn quan trng v c nh hng nhiu

ti hotng ca thp v hiu qu chng ct. ng knh thp chng cng

ln th hiu sut lm vic gia cc vng trn a cng khc nhau nu nh vic

phn b dng chy khng tt. Vic phn b dng chy trn a khng tt dn

n s khc nhau v mc cht lng ( nghing cht lng trn a cng ln

nu kch thc a cng ln) v s ng nht ca thnh phn cht lng trn

a. gii quyt vn ny, cc nh thit k a ra nhiu kiu phn b dng

chy trn mt a khc nhau ty theo iu kin c th (kch thc thp, nguyn

liu ch bin,...) nhm hn ch ti a s khc bit gia cc vng trn mt a.

Vic b tr cc chi tit trn mt a thch hp cho php nng cao hiu qu phntch. Hiu sut s dng din tch cao cho php gim c kch thc thit b

v s lng a trong thp chng ct v m bo c s hotng linh hot

ca thp. Mt s cch b tr a chng ct c m t trong hnh v H-5.15 v

minh habng hnh nh trong hnh H-5.16, H-5.17.

A-kiu dng chy n trn a B-kiu hai dng chy trn a



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C-kiu ba dng chy trn a Dkiu bn dng chy trn a

Hnh H-5.15. Mt s kiu b tra v cc ng chy truyn

Hnh H-5.16. Hnh minh ho s b tr a chng kiu dng chy n

Hnh h -5.17. Hnh minh ho s b tr a chng kiu nhiu dng chy

T cc hnh v cho thy: c rt nhiu cch b tr dng chy cht lng trn

mt a, t mt dng chy n cho ti 3, 4, 5, 6 dng chy ca cht lng trn

mt a. Tng ng vi mi kiu dng chy ca cht lng trn mt a c mt

s b tr a v cc ng chy truyn khc nhau. Trong thit k truyn thng

trc y, phn mt a pha di ng chy truyn thng l phn a cht



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khng lpt chp hoc van dn n gim hiu sut s dng din tch a.

tng din tch s dng hu ch ca a v ca ton thp, mt s thit k hin

nay trong cng nghip ch bin du kh, phn din tch di cc ng chy

truyn cng c s dng vi mt kt cu c bit nh minh ha trong hnh H-

5.18.

Hnh H-5.18. S b tr a chng phn di ng chy tryn

Cu to v hnh dng mt s loi ng chy truyn

ng chy truyn vi chc nng vn chuyn cht lng t a pha trn

xunga pha di, tuy nhin, nu cc ng chy truyn khng c thit k

thch hp v kch thc, hnh dng s nh hng n hotng bnh thng

ca thp chng v hiu qu s dng din tch b mt a chng. Nu kchthc ca ng chy truyn khng thch hp s dn n hin tng cht lng

khng chy kp gy hin tng sc thp hoc lng cht lng trong ng khng

lm ng chy truyn tr thnh ng i tt ca hi. Tt c cc hin tng

ny u dn ti s hotng khng bnh thng ca thp chng ct. Ty theo

quan im thit k, nguyn liu ch bin, v tr lp t, cng sut ca thp

chng,... m ng chy truyn c hnh dng v cu to khc nhau. Hnh dng v

cu to ca mt s dng ng chy truyn c s dng rng ri trong cng

nghip ch bin du kh c m t khi qut trong cc hnh v H-5.19.

Tng dng ng chy truyn c ng dng v tr v loi a nht nh. Cc

dng ng chy truyn m t trong cc hnh H-5.19A, B, C, E, F G, H thch hp

cho v tr ng chy truyn cnh thn thp v thng thp c cng sut ch

bin ln. Dng ng chy truyn ny c dng hnh mng (nhiu khi cn gi tn

khc l mng chy truyn). Cc ng chy truyn c tit din hnh ng trn (hnh

H-5.19D) thng dng cho thp chng ct c cng sut khng ln lm v ch

c mt dng chy n trn mt a. Dng ng chy truyn c tit din trn, hnh



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ng c th dng cho thp c cng sut ln bng cch s dng nhiu ng, tuy

nhin, gii php ny phc tp v hiu qu s dng din tch a chng ct thp.

Mt s dng ng chy truyn ch p dng mt s a v tr c bit. V d,

hnh dng v kt cu ng chy truyn m t trong cc hnh H -5.19K, L ch dng

cho cc a chng cui cng gn y thp, ng chy truyn c kt cu nh mt trong hnh H-5.19Ich p dng cho cc a m v tr , mt phn on

c rt ra gia thp ly sn phm hoc iu chnh hot ng ca

thp. Cc ng chy truyn dng mng hp (hnh H-5.19 J) thng s dng

cc v tr gia a chng ct. Hnh dng ca mt s dng ng chy truyn v s

b tr mt a chng vi cc ng chy truyn c minh ha trong hnh H-

5.20.

A-ngchy truyn Hnh cong u B-ngchy truyn vi kt cu tmchy trn ring bit

C-ng chy truyn hnh cong khng u D-ng chy truyn hnh ng trn



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E-ng chy truyn tm chn nghing F-ng chy truyn tm chn thng

G-ng chy truyn tm chnbc thang H-ng chy truyn c a bt kn

I-ng chy truyn c a thu gom cht

lng ly ra ngoi J-ng chy truyn dng mng hp

K-ng chy truyn cnh t b phn thu

gom cht lng

L-ng chytruyn trung tm t b

phn thu gom cht lng

Hnh H-5.19. Hnh dng v cu to mt s ng chy truyn trong thc t



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Hnh H-5.20. Hnh nhmt s dngng chy truyn v s b tr a

Vic thit k a chng ct c nhiu phng php, tuy nhin, vic phn

chia dng chy trn a v s ng chy truyn thng da trn nguyn tc tng

din tch ng chy truyn theo yu cu c phn chia ra nhiu ng khc nhau

(a c ng knh ln c chia ra nhiu dng chy), da trn lu lng cht

lng chy v din tch hotng ca vng cht lng chy qua. Din tch vng

hotng trn mi dng chy thng c phn b sao cho cn bng nhau,do vy chiu di ca vch chy trn cng phi c iu chnh tng ng

tc dng chy qua ca chy trn mi ng chytruyn l nh nhau. Vic

khng ch tc cht lng cc ca chy trn ging nhau nhm m bo

mc cht lng cc vng trong a tng i ng nht nh hiu qu hot

ng ca cc vng trn a chng l tng i ging nhau.

V thp

V thp l mt tr trn c ch to t thp cacbon pha trong c trng

hp kim chng n mn (ty thuc vo nguyn liu ch bin). V c chc nngchnh l to kt cu c kh lp t a chng ct v cc ph kin bn trong.

Ngoi ra, v thp cn c chc nng to khng gian ring bit vi mi trng

bn ngoi, iu ny c bit quan trng i vi qu trnh chng ct du th v

cc sn phm do kh nng chy n cao. Khc vi thp s dng trong cc

ngnh cng nghip khc, v thp chng ct trong cng nghip ch bin du kh

thng c hn kn, hn ch ti a cc mi ni bng bch nhm trnh hin

tng r r. Dc theo thn thp, ngi ta b tr cc ca ngi phc v cho cng

tc lp t, bo dng thit b.



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Cc thit b ph

Thp chng ct ngoi ct chng ct ra, hotng c cn mt s cc

thit b h tr nh thit b gia nhit nguyn liu trc khi ua vo thp chng

ct, thit b gia nhit y v thit b ngng t sn phm nh.

5.3.2.2. Thp ma. Gii thiu

Ngoi dng thp a, trong ch bin du kh ngi ta cn s dng dng

thp m. Thp m c mt s u im ni bt so vi thp a trong mt s

ng dng. Nh tn tht p sut thp, hiu sut chuyn khi cao hn so thp

a truyn thng m dng thp ny c s dng ch yu trong chng ct

chn khng v p sut thp. Nhng nghin cu gn y khc phc c

mt s nhc im ca cc loi m truyn thng v hin tng thm t

khng u lp m, khuynh hng phn b dng cht lng khng u trong

thp, do vy m cc thp m ngy cng c s dng nhiu hn trong cng

nghip ch bin du kh.

b. Cu to v nguyn l hotng chung

Nguyn l hotng

Thp m hotng da trn nguyn l bay hi v ngng t lin tc ca

cc cu t dng lng thm t trn b mt vt rn.Trong qu trnh bay hi v

ngng t lin tcny, cc cu t c nhit bay hi thp hn s i ln phatrn nh thp chng ct cn cc cu t c nhit bay hi cao hn s tch ra

dn phn di thp. tng cng b mt chuyn khi, m c ch to

theo nhng kt cu c bit. C hai dng m l dng m c kt cu theo quy

lut (structured packing) v dng m sp xp hn n khng theo quy lut

(random packing). Cu to ca m l nhn t quyt nh hiu qu hotng

ca thp. Cu to ca cc loi m s c gii thiu mt mc ring ca bi

hc ny.

Cu to chungThp m in hnh c cu to nh m t trong hnh H -5.21. V hnh thc

bn ngoi v kt cu c kh, cc ng vo ra thp m cng c cu to nh

thp chng ct dng a, ch khc nhau v kt cu cc chi tit bn trong thp.

Vmt cng ngh, thp chng ct dng m cng chia thnh on chng v

on luyn. on chng t y thp ti v tr tip nguyn liu, on luyn t v

tr tip liu ti mt trn cng ca m. Mt thp m in hnh bao gm cc b

phn chnh sau:

- V thp;



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- Cc lp m;

- B phn phn phi cht lng;

- B phn thu gom cht lng;

- Cc chi tit m;

- Cc thit b ph: Thit b ngng t, gia nhit y.Cu to chi tit ca cc chi tit quan trng ca thp m s c trnh by

trong cc mc di y.

c. Cu to mt s b phn ca thp m

Lp m

Hnh H-5.21. Cu to chung thp chng ct dng m

Cc loi m trc y thng gp phi mt s tr ngi trong ng dng l

hin tng thm t cht lng v phn b dng chy khng u trong thp dn

n hiu sut chuyn khi thp. Tuy nhin, trong nhng nm gn y cc dng

m c cc nh bn quyn (Koch-Glitsch, Sulzer, Norton) nghin cu pht



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trin nhm p ng c cc yu cu ca thc t v cc tiu ch: nng cao

hiu sut qu trnh chuyn khi, h gi thnh ch to, chu c mi trng

lm vic khc nghit, d bo dng, kt cu nh,... Nh khuynh hng pht

trin ny m cc loi m mi c a ra s dng khng ch c ci thin

v kt cu nng cao hiu sut qu trnh chuyn khi m cn c thay thbng cc loi vt liu mi ph hp vi cc ng dng c th v c bit l cho

php gim c gi thnh m. Hin nay, trong thc t ngi ta s dng hai

loi m chnh: loi m c kt cu, v loi m xp hn n. Cu to ca tng

dng ny s c trnh by cc phn di y.

m c kt cu

m c kt cu c s dng rng ri trong ch bin du kh c bit l

qu trnh chng ct chn khng v p sut thp. Loi m ny thng c

ch to thnh tng khi, cc tm mng (sau cun thnh lp) hoc c ch

to chuyn bit theo ng knh ca thp.

Hnh H-5.22A. m kim loi l sn

xut theo ng knh thpHnh H-5.22B. Dng m tm li

m dng c kt cu in hnh thng c cu trc hnh hc gm nhiu

tm rt mng (thng l tm kim loi) c dp nhn, sp xp theo trt t

song song nhau vi kch thc v hnh dng ph hp vi kch thc v hnh

dng ca thp chng ct. n gin cho qu trnh ch to v c bit l

cht lng v hi trong m c ng u, b dy ca tng lp m ny c

hn ch mc thch hp. Khi cc lp m ny c xp vo trong thp, cc

lp k tip nhau c chiu nghing vi nhau 900C. Mc ch ca vic thay i

chiu nghing ca cc lp m l nhm mc ch phn b li hng chuyn

ng ca cc dng cht lng v hi trong thp cho ng u cng nh tng

cng tip xc cc pha lng /hi. Trong tng lp m cng phn thnh hai

hng dng chuyn ng khc nhau. Nguyn l hot ng chung ca dng

m ny c minh ha trong hnh H-5.23. Loi m ny c ci thin nhiu



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v tr tip xc gia hai lp trnh hin tng tn tr cht lng b mt tip

xc v gim c tn tht p sut cc b ca pha hi ti im tip xc nh

tng c cng sut ca thp (xem hnh H-5.24).

Hnh H-5.23. Cu to chung v nguyn l hot ng ca lp m

Hnh H-5.24. Cu to mt dng m v kt cu v tr tip xc gia cc lp m

Cc lp m xp trong thp chim ti 60-70% th tch ca thp, phn

khng gian cn li l dnh cho b tr cc chi tit khc nh h thng thu gom v

ti phn phi cht lng, h thng phn phi lng, b phn phn tch pha (lng

ko theo hi),... Hiu sut ca thp m, s bc l thuyt hay s bc chuyn

khi thc t tng ng ca lp m phi xc nh trn thc nghim khngxc nh c bng l thuyt. Hiu sut ca loi thp m khng ch ph thuc

vo kiu dng kch thc ca m m cn ph thuc vo tnh cht ca nguyn

liu ch bin, ng knh thp v p sut lm vic. Chnh v vy, vic thit k

thp m mt cch chnh xc cn phi c cc s liu thc nghim cho mi loi

m c th.

m ri (xp hn n)

Ngoi dng m c kt cu, thp m cn c mt dng kt cu m khc

l dng m ri. Lp m trong thp c hnh thnh nh xp ngu nhin cc



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phn t m ri khng theo mt quy lut nht nh. phn loi thp, i khi

ngi ta cn c vo dng m m chia thp m thnh hai loi: thp m c

kt cu v thp m vi lp m ri. m ri c th c ch to t nhiu vt

liu khc nhau nh gm s, kim loi v cht do. Cc m truyn thng thng

c ch to t gm s, cc loi m th h mi thng c ch to t kimloi v cht do. Cc loi m truyn thng thng dy trong khi cc m

th h mi thng mng hn, b mt ring (din tch mt m trn mt n v

th tch thp) ln nh gim c kch thc thp tng hiu sut qu trnh

chng ct v gim c khi lng thp mt cch ng k. Cc m mi pht

trin thng c ch tobng kim loi v cht do. Tuy nhin, khng c loi

vt liu ch to no hon ton chim u th trong tt c cc ng dng. Cc

m truyn thng ch to t gm rt nhy cm i vi mi trng c kim v

axit HF. Trong khi m kim loi th kh nng thm t b mt m vi mt

s cht lng km v kh nng b n mn cao. m ch to bng cht do nh

hn d lp t, tn tht p sut trn mt bc chuyn khi l thuyt thp, gi

thnh thp, khng lo ngi v hin tng n mn m. Tuy nhin, m cht do

li gp vn thm t nh m kim loi v c bit kh nng chu nhit

cao. Mt s v d v hnh dng v cu to m ri c trnh by trong hnh H-

5.25.

Hnh H-5.25A. Mts dng m truyn thng lm t gm

Hnh H-5.25B. Mts dng mi lm bng kim loi



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Hnh H-5.25C. Mts dng m bng cht do

Cc loi m ri ny c sn xut vi nhiu kch thc khc nhau. ng

vi mi loi m, nh sn xut s cung cp cc c tnh k thut phc v cho

la chn v thit k thp.

B phn phn phi cht lng

Nh cp, mt trong nhng nhc im ca thp m truyn thng

l hin tng phn b pha lng khng u gia cc phn trong thp dn n

hiu qu hotng ca thp thp. Cc nghin cu ch ra rng: cht lng v hi

phn b khng u trong thp m (thm ch c vng b kh) lm nh hng

ln n hiu qu lm vic ca thp. S lng a tng ng thc t (bc

chuyn khi tng ng) ca thp m s gim t l thun vi hiu qu phn

phi lng trong thp (xem hnh H-5.26) Hin tng phn b cht lng khngu trong thp ph thuc vo nhiu yu t nh: kt cu ca m, kch thc

ca thp, hiu qu lm vic ca b phn phi,... Kt cu ca m ngy cng

c ci thin khc phc hin tng ny. Tuy nhin, b phn phn phi

lng nh hng khng t ti hiu qu phn phi cht lng v do nh hng

ti hiu qu hotng ca thp.

ci thin hiu qu hot ng ca thp, b phn phn phi cht lng

trong thp chng ct dng m ngy cng c quan tm nghin cu v hon

thin. Trong thp m, mi mt tng m (gm nhiu lp m) u c mt h



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thng phn phi lng pha trn. Ty thuc vo c im thit k v khong

cch cn thit pha hi tch khi lp m m h thng ny c lp t

trong khong t 0- 200mm so vi mt trn ca lp m. Mt h thng phn

phi lng tt phi t c cc yu cu sau:

- Cht lng phn phi ng nht;- Hotng c trong khong cng sut thp thch hp;

- Lm tn tht p sut pha hi nh;

- C kh nng chng li hin tng tc nghn v ng cn;

- Thi gian lu cht lng thp;

- Phi hp c tnh nng ti phn phi cht lng cho cc m tip theo.

Mi yu t ny c nhng nh hng ring bit ti hotng ca thp, cc

ch tiu ny l ch cn hng tica cc nh sn xut thp m ci tin h

thng phn phi lng ca mnh. Mt h thng phn phi l tng s phn phi

lng u trn mi n v din tch b mt m. V mt l thuyt, t c

iu ny cn phi c v tn s dng phn phi.

Hnh H-5.26.nhhng ca phn phi cht lng nhot ng thp m

iu ny hon ton bt kh thi trong thc t vi trnh cng ngh hin

ti. H thng phn phi trong thc t ca cc nh bn quyn ch t ti mt gii

hn mang tnh kh thi hn da trn cc tiu ch:

- Cc u phn phi cht lng c phn b theo mt s ng nht;

- Cc u phn phi phi m bo hotng lin tc;



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- Cc u phn phi phi c t ti mt v tr thch so vi v thp;

- Hn ch ti a s khc bit lu lng gia cc u phn phi.

Da trn tiu ch ny, cc h thng phn phi c pht trin. Mt s dng

h thng phn phi ang s dng trong thc t c m t trong hnh H-5.27.

H-5.27A. Hthng phn phi dng

ng Hnh xng cH-5 27B. Hthng phn phi kt hp

hp v ng xng c

H-5.27C. Hthng phn phi dng

mngH-5.27D. Hthng phn phi dng

mng c u ng phn phi

H-5.27E. Hthng phn phidng

ng chy trn

H-5.27F. Hthng phn phi dng

mng Hnh rng ca



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H-5.27G. Hthng phn phi hpH-5.27H. Hthng phn phi dng

ng

Hnh H-5.27. Cuto mt s dng ng phn phi lng trong thp chng ct

dng m

B phn thu gom cht lng

Nh trnh by trn, mt trong nhng nhc im ca thp m l

hin phn b dng lng v hi khng ng u gia cc vng trong thp, cbit l nhng v tr cch xa nh m. Mc d cc loi m th h mi ci

thin c rt nhiu nhc im ny, tuy nhin, vi cc thp c chiu cao ln

v ng knh rng th vn phi phn phi li dng lng hi trong thp. Mt

khc, do kt cu v nguyn l hotng (v d on tip liu) cng yu cu cn

phi thu gom cht lng v ti phn phi li. Trong mt s trng hp, ngi ta

thit k tch hp h thng thu gom v phn phi cht thnh mt h thng duy

nht. Thng thng, cc h thng thu gom lng c thit k c th lp t

bng cch a cc chi tit qua ca ngi, hn ch lp bng mt bch gia thn

thp. H thng thu gom cht lng phi t hiu qu cao, kt cu n gin

nhng khng c lm nh hng nhiu n tn tht p sut pha hi. Mt s

dng h thng thu gom cht lng trong thp m c trnh by trong hnh v

H-5.28.

H thng thu gom cht lng dng a (m t trong hnh H-5.28A) thng

c s dng thu gom v rt mt phn hay ton b cht lng ra pha ngoi

thp. Tuy nhin, dng thu gom ny thch hp nht cho vic thu v cp lng cho

mth thng ti phn phi lng hay mt a pha di. Dng thu gom lng

ny c thit k rt linh ng ty thuc vo yu cu ng dng c th. Mt s c

im k thut ng ch ca h thng thu gom dng a l c th p dng cho

mi kch thc thp chng ct, th tch cht lng thu gom ln c th lp t

mt ng ng chy truyn.

H thng thu gom cht lng dng hnh mng (m t trong hnh H-5.28B)

thng c s dng thu mt phn hay ton b cht lng ra ngoi. Loi thu

gom ny c s dng thch hp trong mi trng lm vic m vn gin



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n nhit l vn gy kh khn cho vic s dng cc dng thu gom cht lng

khc. H thng ny thng c p dng cho cc thp c ng knh ln hn

1000mm vi mt s c tnh k thut ch yu: din tch thong (cho hi i)

chim khong 25-40%. Vi loi thit b thu gom dng ny cn hn ch ti a

vic lp t bng phng php hn ti hin trng.H thng thu gom m t trong hnh H-5.28C c s dng thu gom

cht lng v rt ra ngoi hoc ti phn phi li lp m tip theo. Loi ny

thng c la chn cho h thng thu gom cht lng gia cc lp m do tn

tht pha hi qua h thng thu gom ny thp. Ngoi ra dng thu gom cht lng

ny cng c s dng ti v tr tip nguyn liu do nguyn liu a vo thp

c th ha ln vi pha lng thu gom vnh khuyn ca h thng thu gom m

khng cn mt ng ng dn nguyn liu ring. Do c khong ng dng rng

ri nn h thng thu gom cht lng dng ny nhiu v tng ng c nhiu kiu

kt cu chi tit khc nhau ty thuc vo ng dng c th. Cc kt cu m t

trong bi hc ny ch l mt kiu in hnh.

Hnh H-5.28A. Hthng thu cht lng

dng a

Hnh H-5.28B. Hthng thu cht

lng dng mng

Hnh H-5.28C. Hthng thu cht lng dng chevron

Kt cu m



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cc lp m t ng v tr trong thp cn c mt kt cu lp m.

C hai yu t cc k quan trng cn phi c xem xt trong thit k b phn

m:

- B phn m phi c kh nng gi c lp m di iu kin

hotng ca thp khng b nh hng bi hnh dng, kch thc cam, nhit thit k, chiu dy lp m, lng cht lng lu gi, vt

liu ch to, n mn cho php, cc ti trng ph khc trn lp m

v tnh trng khng n nh ca thp.

- Phi c t l din tch t do ln cho php khng khng hn ch cc

dng chuyn ng ngc chiu ca lng t trn xung, hi t di i

ln nhm gim thiu tn tht p sut cc b.

Mt s dng kt cu b phn c m t trong hnh H-5.29. Cc dng

m m t trong hnh H-5.29A, B c thit k dng cho loi m c kt

cu cn dng m m t trong hnh H-5.29C, D c thit k dng cho

loi m ri. a m (nh m t trong hnh H-5.29A c s dng trong

cc thp c lp m mng v vn s dng khng gian hiu qu l mt yu

t cn c xem xt. Dng a ny thng c s dng cho cc lp m

mng trong thp chng ct du p sut kh quyn v thp chng ct p

sut chn khng.

Kt cu m kiu vung (hnh H-5.29B) c tng din tch mt thongrt ln v ng nht cho php cht lng v hi i qua khng gii hn (trong

phm vi cng sut ca thp), v vy, khng lm nh hng ti cng sut ca

m. Loi kt cu m ny p dng cho mi di ng knh thp v mi

dng m (c kt cu). Vi thp c ng knh nh c mt bch thn thp, a

m c th ch to mt kt cu duy nht, nhn chung kt cu m kiu

ny c ch to gm nhiu phn v lp t thc hin bng cch a tng

phn qua ca ngi ca thn thp.

Hnh H-5.29A. B phn dng a

dng cho m c kt cu

Hnh H-5.29B. B phn dng

vung dng cho loi m c kt cu



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Hnh H-5.29C. B phn kiu a

dng cho loi m ri ti trng nhHnh H-5.29D. B phn vi din

tch mt t do cao cho loi m ri

Kiu a m ri ti trng nh (hnh H-5.29C) c thit k v s dng

cho cc loi thp m c ng knh nh v lp m c khi lng khng ln

lm. Loi a ny c ch to t thp cn.

Np gi mTrong qu trnh hot ng, c bit l trong giai on khi ng thp,

thng gp nhng bin ng bt thng v p sut dn n hin tng x

lch lp m khi v tr ban u nh hng n kt cu lp m. khc phc

tnh trng ny, pha trn lp m ngi ta thng lp thm mt tm chn (np

gi m) c nh lp m gii hn v v tr thch hp. Ty theo loi m

m cc tm ngn ny c yu cu v kt cu khc nhau.

- - i vi m c kt cu: Np gi m c s dng khi lp m c

kh nng b x dch v tr khi gp nhng bin ng bt thng v ch

hotng ca thp. Tuy nhin, vi cc thp hotng vi tn tht p

sut thp, t l sc thp thp v khng d xy ra hin tng sung p

trong thp th khng cn thit phi lp t np gi m. i vi thp

m c kt cu th yu cu v np gi m khng qu kht khe, v vy,

trong mt s trng hp, b phn phn phi v m pha trn

kim lun vai tr ca np gi cho lp m tip theo. Cu to v hnh

dng ca mt s dng np m cho lp m c kt cu c minh hatrong hnh H-5.30A, B. Loi c kt cu nh hnh H-5.30A c thit k

cho cc thp c ng knh ln khng xy ra nhiu cc hin tng sc

thp hoc khng mt n v ch cng ngh. Thng thng, kiu

m ny c thit k tch hp vi b phn phi, phn m pha

di, cn phn phn phi lng c gn pha trn nh tit kim

c khng gian v vt liu ch to. Np gi m c kt cu hnh

xng c (hnh H-5.30B) ph hp vi tt c kch thc ca thp, hn

ch ti a nh hng ti cc dng lng hi trong thp. Dng np gi



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ny c thit k i km vi cc loi m c kt cu dng tm mng

hoc li kim loi. Cng c th lp t tch hp dng np gi m ny

vi h thng phn phi.

Hnh H-5.30A. Np gi m kt

hp vi b phn phn phi

Hnh H-5.30B. Np gi m hnh xng c

Hnh H-5.30C. Np gi m kiu

li vi lp m c cng sut cao Hnh H-5.30D. Np gi m kiu li

- -i vi m ri: Np gi m lun c yu cu s dng i vi loi

m ri trong iu kin d xy ra hin tng to lp tng si pha trncng ca lp m do tc dng hi trong thp to ra. i vi dng

m ri khi xy ra hintng bt thng hoc thp b sc th tn tht

p sut s tng ln nhanh chng khng th kim sot c, khi hin

tng to lp tng si trn nh lp m thng xy ra. Tuy nhin, iu

kin to lp tng si trn pha nh m l rt kh tnh ton v d

on v vy gii php d phng tt nht l lp t mt b phn hn ch

hin tng ny. Trong thc t ngi ta c hai gii php: lp t np

ngn hoc mt kt cu chng sung ng. Gii php n gin nht hayc s dng l lp t np ngn m pha nh lp m.

Cu to v hnh dng ca mt s dng np m cho lp m ri c minh

ha trong hnh H-5.30C, D. Cc np gi m ny, ty theo ng dng c th m

c th c gn cng vo thn thp hoc di chuyn t do trn b mt m.

5.3.2.3. So snh cc loi thp chng ct v phng hng la chn

Trong qu trnh thit k, mt vn lun c t ra l la chn kiu thp

no cho thp chng ct. Khng c mt loi thp no c u im hon ton

trong mi ng dng. Mi loi c nhng u nhc im ring, ty tng ng



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dng c th m xem xt la chn. c c s cho vic la chn dng thp,

di y trnh by mt cch khi qut u nhc im ca hai loi thp m v

thp a theo quan im ca Max S.Peters, Klaus D. Timmerhaus v Ronald E.

West:

- Hiu qu ca mt bc chuyn khi i vi cc thp m phi da trnth nghim thc t vi mi kiu m c th. Hiu sut ny khng ch

ph thuc vo hnh dng kch thc ca m m cn ph thuc vo

mt lot cc yu t khc nh tc dng cht lng, tnh cht ca

nguyn liu, ng knh thp, p sut lm vic v mc phn tn ca

cht lng trn b mt m.

- Do vic phn tn cht lng ng u trong thp m kh khn, vic

thit k s dng thp a c coi l tin cy hn v s dng h s an

ton thp hn khi m t ltc chuyn khi pha lng vo pha hi l

thp.

- Thp a c th c thit k hotng trong mt khong rng tc

dng lng trong thp m khng xy ra hin tng sc thp.

- Thp a c u tin la chn trong trng hp cn phi lm ngui

gia chng ly nhit ca pha lng. Cht lng c th c a ra

trao i nhit bn ngoi thp.

- Nu cht lng cn chng ct c cha cc ht rn phn tn th s dngthp chng ct dng a s c u tin la chn do thp a d dng

lm v sinh hn.

- Tng khi lng kh ca thp chng dng a thp hn so thp chng

dng m c thit k cng cng sut ch bin. Tuy nhin, tng

trng lng thp t (k c cht lng cha trong thp) ca hai dng

thp l tng t nhau.

- Khi s thay i nhit bin i trong mt bin rng trong qu trnh

hotng, thp a thng c la chn do s gin n nhit d lmhng lp m.

- Cc d liu, thng tin phc v cho thit k thp a thng c sn v c

tin cy cao hn so vi thp m.

- Thp m thng c la chn nu cht lng em ch bin c

khuynh hng d to bt.

- Thp dng m ri nhn chung khng c thit k vi ng knh ln

hn 1,5 m v ng knh ca thp a thng mi nhn chung him khi

nh hn 0,67 m.



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- Thp m thng c gi thnh r v d ch to hn so vi thp a khi

nguyn liu ch bin c tnh n mn cao.

- Lng cht lng cha trong thp m thng t hn rt nhiu so vi

thp a.

- Vi cng cng sut ch bin thp m c th c tn tht p sut thphn so thp a. Mt khc, vi kt cu ca thp m kh nng mt n

nh ca v thp trong iu kin chn khng thp, thp m l tng

cho qu trnh chng ct chn khng.

Trn y ch l nhng nh gi chung, la chn dng thp no cho mt

ng dng c th cn phi xem xt nhiu kha cnh kinh t, k thut v vn

mang tnh cht tin quyt la chn ph hp. Di y s gii thiu c th

mt s qu trnh chng ct trong cng ngh lc ha du.

5.4. CC QU TRNH CHNG CT IN HNH

5.4.1. Chng ct du th p sut kh quyn

5.4.1.1. Gii thiu chung

Nu nh qu trnh cracking c v nh l tri tim ca nh my lc du th

phn xng chng ct du th p sut kh quyn (Crude Distillation Unit

CDU) c xem nh ca vo chnh ca ngi nh. S ch bin ca nh my

gn nh c tch hp ngay trong thit k thp chng ct du th bi l cc

phn on tch ra t thp chng ct s l sn phm trc tip hay l nguynliu cho cc qu trnh ch bin tip theo. Hiu qu ca qu trnh ch bin tip

theo nh hng nhiu bi thit k v hotng ca thp chng ct du th

p sut kh quyn.

5.4.1.2. Mc ch ca phn xng

Mc ch ca phn xng chng ct du th p sut kh quyn l phn tch

du th thnh cc phn on theo cc ng dng tng ng. Thng thng cc

phn on c tch ra t phn xng ny l: Kh ho lng (LPG), phn on

naphtha (mt s phn xng chng ct du th c thit k tch phnon ny thnh hai phn on ring naphtha nng v naphtha nh), phn on

kerosene, phn on diesel nh (LGO), phn on diesel nng (HGO) v cn

chng ct (residue). Mt s phn on tch ra t phn xng chng ct du

th p sut kh quyn c th c coi l sn phm cui cng hoc l cu t

pha trn (sau khi c x l tp cht thch hp) m khng cn phi ch bin

tip nh phn on Kerosene(sn phm thng mi l du ho v nhin liu

phn lc), phn on diesel (l sn phm thng mi diesel hoc l cu t pha

trn diesel), phn on diesel nng c th c s dng lm cu t pha diesel,



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du t l hoc a i ch bin tip. Mt s phn on cn phi c a i

ch bin tip nng cao hiu qu kinh t ca nh my, trong , c bit l

cn chng ct l nguyn liu cho qu trnh cracking. Cc phn on naphtha

nng c a i reforming, phn on naphtha nh c a i ng phn

ho thu cu t pha xng c cht lng cao.



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Hnh H-5.30. S cng ngh phn xng chng ct du th p sut kh

quyn vi mt thp chng ct chnh



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5.4.1.3. S cng ngh

a. S cng ngh

S cng ngh ca phn xng chng ct du th p sut kh quyn

nhn chung khng c s khc bit nhiu, mc d nguyn liu du th rt khc

nhau. Cc phn xng chng ct du th thng ch c khc bit mt cht phn tch cc phn on nh (t naphtha tr ln). Mt s s cng ngh

in hnh ca phn xng ny c trnh by trong cc hnh H -5.30 v H-5.31.

Mi mt s c mt u im nht nh. Tuy nhin, s cng ngh m t

trong hnh v H-5.30 thng c s dng thit k cc nh my mi hin

nay. S ny ph hp ch bin nhiu loi du t nng n nh, song vi s

mt thp thp chng ct chnh ny, thp chng ct s phi lm vic ch

nng nhc hn. S cng ngh phn xng chng ct nh m t trong

hnh H-5.31 thng s dng cho cc nh my thit k trc y ch bin

du th c thnh phn nh cao (c bit l LPG v naphtha nh) v cha nhiu

kh hydrosulfide (H2S) c tnh n mn cao.

b. M t qu trnh

Theo cc s cng ngh nu, du th sau khi c tch nc b

cha c bm ti thit b trao i nhit tn dng dng sn phm nng c

nhit cao hoc cc dng du rt ra t thp chng ct chnh ( iu khin

nhit thp). Du th t c nhit nht nh s c b sung thmnc sch ri a vo thit b trn tnh trc khi a vo thit b tch mui.

Mc ch ca vic b sung thm nc v khuy trn l ho tan mui cha

trong du vo nc sau tch nc cha mui ra thit b tch mui. Du

th sau khi c b sung nc s c a vo thit b tch mui. Ti thit b

tch mui, hn hp du th v nc dng nh tng c ph v. Du th

v nc c tch lm hai pha ring bit. Du th kh mui c tch ra

v a i ch bin tip. Nc cha mui mt phn tun hon li thit b tch

mui, phn cn li c a ti h thng x l nc thi ca nh my. Du thsau khi c tch mui s c gia nhit tip nh cc thit b trao i nhit tn

dng cc dng sn phm i ra t thp chng ct chnh (nh Kerosene, LGO,

HGO v cn chng ct). Nu s cng ngh ca phn xng c s dng

thp tch s b th du th dc a vo thp chng ct s b trc. Ti thp

chng ct s b, cc thnh phn hydrocacbon nh nh methane, ethane,

propane, buthane v hydrosulphure (H2S) c tch ra nh thp. Mt phn

phn on naphtha nh cng ko theo sn phm nh thp chng ct s b.

Du th sau khi c tch s b cc thnh phn nh c a ti l gia nhit



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nng nhit thch hp ph hp cho qu trnh chng ct (nu s khng

s dng thp chng ct s b th du th sau khi tch mui v a qua hng

lot cc thit b trao i nhit s c a ti l gia nhit ny). Sau khi i qua l

gia nhit, nhit ca du th s tng ln mc thch hp cho qu trnh chng

ri c a vo a tip liu ca thp chng ct. Trong thp chng ct chnh,cc phn on chnh nh naphtha nng, kerosene, GO nh, GO nng c

tch ra thn thp, c lm sch thm cc ct sc bn cnh thp chng

ct chnh ri a ti cc b cha trung gian. Phn on nh (naphtha nh)

c tch ra nh thp cn phn on cn c tch ra y thp. Cc

dng sn phm t thp chng ct chnh c nhit cao c em i trao i

nhit vi du th trc khi lm ngui tip nh cc thit b trao i nhit bng

khng kh hoc nc lm mt. iu khin nhit lm vic ca thp nhm

nng cao hiu qu qu trnh phn tch p ng tiu chun sn phm ca tng

phn on, pha di y thp chng c b phn gia nhit bng hi thp p

qu nhit v dc thn thp b tr cc im rt cht lng ra bn ngoi iu

chnh nhit cht lng sau a quay li thp chng. Mt s phn on

cha c tch ra khi nhau (LPG v naphtha nh) s c a ti thp n

nh (Stabilizer), ti y cc hydrocacbon nh (C1, C2) a ti h thng kh

nhin liu nh my, LPG c tch ra a ti h thng thugom v x l kh,

naphtha nh c tch ra y thp a i x l tip. Nu ton b phnon naphtha (c naphtha nng v naphtha nh) v cc hydrocacbon nh c

tch ra cng nhau nh s cng ngh hnh H-5.30 th hn hp ny s c

a ti cc thp ph phn tch ring bit thnh LPG, naphtha nh v

naphtha nng. Trc ht hn hp c a ti thp n nh (Stabilizer)

tch LPG ra khi naphtha. Phn on naphtha tch ra y thp n nh c

a thp tch naphtha (Naphtha Splitter), ti thp tch ny naphtha nh c

tch ra nh thp cn naphtha nng c tch ra y thp. Tuy nhin, nu

nh trong nh my lc du c c hai phn xng reforming v isome ho th cth thp tch naphtha s c di chuyn sang phn xng x l naphtha bng

hydro (NHT) cho ph hp vi qu trnh cng ngh. Naphtha sau khi c x

l mi c tch ra thnh hai phn on naphtha nng v naphtha nh nhm

trnh u t hai phn xng x l naphtha ring bit. Naphtha nng sau x l

l nguyn liu cho qu trnh reforming cn naphtha nh sau khi x l c s

dng lm nguyn liu cho qu trnh isome ho.

5.4.1.4. Cu to v nguyn l hotng mt s thit b chnh trong phn

xng



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a. Thit b tch mui

Trong du th thng cha mt lng tp cht di dng mui v kim

loi. Cc tp cht ny cn phi tch ra khi du th bi v chng s b ng cn

trn b mt trao i nhit ca cc l t v thit b trao i nhit lm gim hiu

sut truyn nhit ca cc thit b ny.Ngoi ra, cc tp cht ny cn gy ngc xctc, hin tng n mn thit b cc qu trnh ch bin tip theo. Trong

qu trnh kh mui, mt lng nc sch c a vo du th ho tan

mui trong du vo pha nc v sau tch ring hai pha du v nc ra khi

nhau. Mui trong du th c tchra cng nc. C nhiu phng php tch

mui ra khi du th, tuy nhin, trong thc t s dng hai phng php chnh

l phng php ho hc v phng php tnh in.

Nguyn l qu trnh kh mui

Nguyn l hotng chung ca qu trnh tch mui l b sungnc vo

du th to nh tng ho tan ti a mui trong du th sau ph nh

tng gia du v nc tch ring bit hai pha du v nc nh m

mui trong du th c tch ra. Cc phng php tch mui ch khc nhau v

phng php ph nh tng. Phng php ho hc s dng ho cht ph

nh tng, cn phng php tnh in dng in trng ph nh tng. Do

phng php tnh in c s dng rng ri trong thc t nn di y s ch

trnh by chi tit v nguyn l v cu to thit b kh mui bng phng phplng tnh in.

Cu to v nguyn l hotng thit b kh mui

S cng ngh chi tit ca thit b kh mui c trnh by trong hnh H-

5.32. Theo s ny, du th c b sung thm mt lng nc ri i qua

mt thit b trn tnh to hn hp nh tng nhm tng mc phn tn ca

nc vo du th nng cao hiu qu ho tan mui t du th vo nc.

Du th sau khi qua thit b trn tnh c a vo thit b lng tnh in.Thit

b lng tnh in da trn nguyn l tch in ca cc ht nc nh trong intrng cao, cc ht nc tch in sau s ht nhau do lc tnh in nhp

thnh cc ht nc ln hn v lng xung pha di. Nh qu trnh ny m

dung dch nh tng du th v nc b ph v. Du v nc cha mui ho

tan c tch thnh hai pha ring bit v a ra khi thit b.

to in trng, trong thit b lng tnh in lp hai bn cc c ni

vi cc ngun cao p. in p gia hai in cc ti thiu khong 16000 vn

c th tch in cho cc ht nc trong nh tng. Lng nc ti u a vo

du th trong khong t 3-8% th tch du th, ty thuc vo tnh cht ca du



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th. Nhit ca du th trc khi a vo thit b trn tnh thng trong

khong 1301500C. Khi nc sch b sung vo du th, mui chatrong du

s chuyn sang cc ht nc phn tn trong du do kh nng ho tan mui

ca nc tt hn. Cc ht nc ny khi i qua in trng cao p s b tch

in. Cc ht nc b tch in s nhp dn li vi nhau thnh cc ht c kchthc to dn v lng xung pha di do nc c khi lng ring ln hn du

th. ngn chn qu trnh bay hi ca cc phn on nh trong du th dn

nkh nng pht chy trong iu kin nhit v mi trng cao p, p sut

trong thit b lng tnh in c duy tr mc t 9 -12Kg/cm2. Du th c

kh mui bng phng php ny cho php tch c ti t 90- 95% lng

mui, nu hm lng mui trong du cao hoc m bo an ton vn hnh,

ngi ta lp hai bc tch mui. Du th c tch mui hai bc cho php gim

c 95-99% lng mui ban u. Cu to v nguyn l hotng ca thit b

lng tnh in c m t trong hnh H-5.33.

Hnh H-5.32. S cng ngh thit b kh mui

Theo s cu to thit b lng tnh in bao gm cc b phn chnh sau:Bnh lng, in cc cao p, my bin th v cc h thng ng ni vo ra thit

b.

b. Thp chng ct chnh

Thp chng ct chnh l thit b quan trng nht ca phn xng chng

ct du th. Thp c nhim v phn chia du th thnh cc phn on khc

nhau theo mc ch s dng. S hotng chung ca thp chng ct chnh

nh trnh by trong hnh H-5.34 di y. Nguyn l hotng chung ca thp

chng ct chnh cng ging nh nguyn l trnh by trong mc 2 phn III



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ca bi hc ny. Thp chng ct chnh c th l kiu thp a hoc thp kiu

m, tuy nhin s thp dng kiu a chim t l ln hn.

Qu trnh hotng

Du th sau khi c gia nhit (thng t 310-3700C ty theo s cng

ngh v tnh cht du th) c a vo a tip liu thp chng ct chnh. T iy, cc cu t c nhit si thp s bay hi ln cc a pha trn ca thp,

phn lng s theo ng chy truyn i xung pha di. Nhit vo thp rt

quan trng i hotng ca thp. Nu nhit khng cao th cht lng

cc phn on khng m bo, ngc li nu nhit du qu cao s dn n

hin tng cracking nhit lm tng cng sut thp t ngt ngoi tnh ton lm

nh hng n hiu qu hot ng v cht lng sn phm. Cc cu t

hydrocacbon nh s c phn b cng nhiu pha trn ca thp, cc cu t

c nhit si cao s dn tp trung cc a pha di thp.

Hnh H-5.33. S cu to v nguyn l hot ng ca bnh kh mui kiu

lng tnh in

Cc phn on Kerpsene, Go nh, GO nng c rt ra thn thp v

a vo cc ct sc tng cao cht lng phn on theo tiu chun cht

lng. Phn on naphtha v cc hydrocacbon nh hn c tch ra nh

thp, ngng t ri a ti cc thp ng nh v thp tch naphtha phn chia

tip thnh cc phn on LPG, naphtha nh, naphtha nng. Tuy nhin, trong

mt s s th phn on naphtha nng cng c tch ra thn thp. Cn



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chng ct c tch ra pha y thp sau khi lm ngui s c a ti b

cha hoc a trc tip ti phn xng cracking. cung cp nhit cho qu

trnh chng luyn v qu trnh chng ct xy ra thun li pha y thp ct

chnh c gia nhit bng hi qu nhit thp p. Vic sc hi y thp cn

nhm mc ch tch trit cc cu t nh cn cha trong phn lng ythp nng cao hiu sut thu hi cc cu t nh. Ngoi ra, hi dng gia nhit

trc tip du th lm gim p sut ring phn ca du th trong pha hi do vy

qu trnh chng ct c th tin hnh nhit thp hn.

iu khin qu trnh hotng ca thp chng ct v nng cao hiu

sut phn tch, mt phn cht lng pha trn nh thp c cho hi lu li

thp, ngoi ra dc theo thn thp ngi ta thit k mt s v tr rt cht lng

ra iu chnh nhit ca thp ti cc v tr cc b.

Hnh H-5.34. Cuto v nguyn l hot ng ct chng ct chnh

Cu to



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Thp chng ct chnh trong phn xng chng ct du th p sut kh

quyn c th s dng c dng thp a v dng thp m. Tuy nhin, dng

thp a c dng ph bin hn. Mt thp chng ct chnh thng bao gm

khong 40-55 a chng ct (ty thuc vo s cng ngh v tnh cht du

th) v cng c chia thnh hai phn: on chng v on luyn. onchng thng c khong 5-7 a, on luyn c khong 35-50 a. Cc kt cu

bn trong thp (cc a, chp, ng chy truyn,..) thng c ch to bng

thp hp kim hoc thp khng rty theo tnh cht n mn ca du th. V thp

thng c ch to t thp cacbon gim gi thnh, tuy nhin, bo v

lp v thp cacbon, pha trong thp c ph hoc trng mt lp hp kim.

Cng pha y thp th kh nng n mn cng ln do nhit cao, do vy,

lp ph hp kim ny phi dy v c kh nng chu n mn tt hn. Pha y

thp c h thng sc hi trc tip, tng hiu qu qu trnh sc nhng nhit

hi khng qu cao nh hng ti ch hotng ca thp. Thng thng

hi s dng l hi thp p qu nhit. Cu to chi tit ca cc chi tit bn

trong thp (cc loi a, cc loi m, ng chy truyn,...) c trnh by

trong mc 2 phn IIIca bi hc ny. V thp chng ct chnh c ch to v

lp ghp bng phng php hn, vic s dng bch ni thn rt hn ch (ngoi

tr trng hp s dng thp m). Vic lp t cc chi tit bn trong thp phi

c tnh ton ngay t giai on thit k m bo vic vn chuyn, lp ghpcc chi tit ny thc hin qua ca ngi. Trong thp b tr cc a c cu to

c bit vi cc phn cha cht lng ln c th rt cht lng ra khi ngoi

thp.

5.4.2. Chng chn khng

5.4.2.1. Gii thiu chung

Du th sau khi c phn tch p sut kh quyn thu c cc phn

on nh v cn chng ct. i vi mt s loi du nh v sch th cn ny c

th a thng ti phn xng cracking xc tc cn. Tuy nhin, vi a s ccloi du th cn ny khng th a thng ti phn xng cracking c m

cn phi tch bt cc phn on khng ph hp cho qu trnh cracking.

tch tip cc phn on ny cn phi c thc hin nhit tng cao. Khi

thc hin chng ct nhit cao s xy ra hin tng cracking nhit to ra

cc sn phm khng mong mun. iu ny khng ch lm nh hng ti hot

ng ca thit b m cn nh hng ti hiu sut thu hi sn phm chung ca

nh my. khc phc vn ny, ngi ta tin hnh chng ct cn du th

p sut thp (p sut chn khng), khi nhit si ca cc cu t s gim



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xung nh cc phn on tch ra d dng nhit thp khng xy ra qu

trnh cracking. Qu trnh chng ct chn khng thng tin hnh iu kin p

sut trong khong t 2540mmHg ( vng tip liu).

5.4.2.2. Mc ch ca phn xng

Mc ch ca phn xng chng ct chn khng l tch tip cn chngct p sut kh quyn thnh mt s phn on ph hp cho cc qu trnh

cng ngh ch bin tip theo nh qu trnh sn xut nha ng, qu trnh

cracking,... nhng khng lm nh hng ti hiu sut thu hi sn phm. Do

qu trnh chng ct din ra p sut chn khng nn nhit qu trnh chng

ct thp hn nh hn ch ti a qu trnh cracking nhit ca du. Mt s

phn on chng ct chnh c tch ra t phn xngchng ct ny l phn

on diesel, phn on chng ct chn khng (VGO) lm nguyn liu cho qu

trnh cracking v phn on cn chng ct chn khng dng sn xut nha

ng hoc cho pha trn du t l.

5.4.2.3. S cng ngh

S cng ngh qu trnh chng ct chn khng c m t trong hnh

H-5.35. Theo s cng ngh ny, cn chng ct du th sau khi i qua mt

lot cc thit b trao i nhit c a ti l gia nhit nng nhit ca

nguyn liu ti gi tr thch hp. Nhit ca nguyn liu a vo thp chng

ph thuc vo tnh cht ca cn du nh khong nhit si, kh nng tocoke,... Nhit nguyn liu sau gia nhit thng thng trong khong t

3804550C.

Trong thp chng ct, cc phn on nh v kh khng ngng c tch

ra nh thp. Kh khng ngng s c a ti h thng kh nhin liu ca

nh my, cc cu t nh ko theo sau ngng t s c tch ra v a v h

thng du thi (slop oil) ca nh my ch bin li. Cc phn on chng ct

nh (LVGO) v phn on du chng ct chn khng nng (HVGO) c tch

ra gia thp. Cc phn on ny s c a i ch bin tip thu hi snphm c gi tr cao hn. Cn chng ct chn khng c tch ra y thp.

Phn on cn chng ct chn khng l nguyn liu cho sn xut nha ng

(nu tnh cht cn p ng c yu cu) hoc l cu t pha du t l.

nng cao hiu qu qu trnh phn tch, mt phn du ra (washing oil) a

tun hon t thp v l gia nhit.



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Hnh H-5.35. S cng ngh qu trnh chng ct chn khng

5.4.2.4. Cu to v nguyn l hotng ca cc thit b chnh

Qu trnh chng ct chn khng n gin bao gm cc cm thit b chnh

l thp chng ct, l gia nhit v h thng to chn khng.

a. Thp chng ct

Thp chng ct chn khng thng s dng l thp dng m gim ti

a tn tht p sut. Thp chng ct theo ch cng ngh c chia thnh

nm vng khc nhau l vng phn on chng ct chn khng nh (LVGO),vng on chng ct chn khng nng (HVGO), vng du ra (wash oil

section), vng bay hi (flashing Zone) v vng sc (stripping section). S

cu to n gin ha ca thp chng ct chn khng c m t trong hnh

H-5.36.

Kch thc, cu to cc vng ca thp l khc nhau m bo hot

ng thp bnh thng ng thi tit kim chi ph ch to. Vng sc ca thp

v vng tch phn on VGO nh thng c ng knh nh hn do lu lng

hi thp hn cc vng khc trong thp. chn khng ca thp nh hng



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nhiu n ch hotng v kch thc ca thp v do nh hng n

chi ph u t thit b.

Hnh H-5.36. S nguyn l hot ng v cu to thp chng ct chn khng

p sut ti vng bay hi s quyt nh lng hydrocacbon s bay hi ngay

v tr tip liu. p sut cng thp th lng hydrocacbon bay hi cng ln (

cng iu kin nhit nguyn liu vo thp l nh nhau), chnh v vy m vic

ch to lp t lp m, cc ng ng ni t my ht chn khng ti vng

bay hi phi m bo gim ti a tn tht p sut. Vic gim tn tht p sut

cho php tit kim c chi ph vn hnh mt cch ng k. p sut hotng

ca thp thp do vy lng hydrocacbon bay hi trn mt n v th tch

nguyn liu ln dn n lm tng ng k ng knh thp chng, chnh v vy

ng knh thp chng ct chn khng thng ln hn so thp chng ct du

th p sut thng. Cu to cc chi tit bn trong thp (m, b phn phi,

b thu gom cht lng) c trnh by trong mc 2.2 phn III ca bi hc ny



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(Thp m). Tuy nhin, dng thp s dng trong chng ct chn khng thng

s dng loi m c kt cu. Ch chn khng trong thp c to ra v duy

tr bi my ht chn khng.

b. H thng to chn khng

to chn khng cho thp chng ct, ngi ta c th s dng my htchn kiu vi phun hi (Ejector) vi h thng ngng t Baromet hoc bm chn

khng v thit b ngng t gin tip. H thng to chn khng bng vi phun

vi thit b ngng t Baromet c gi thnh thp hn v c s dng rng ri

trong nhng nm trc y. Tuy nhin, phng php ny lm nhim bn

ngun nc thi ln, v vy, hin nay, h thng bm chn khng kt hp vi

thit b ngng t gin tip c thay th mc d chi ph u t cao hn. Cng

sut v s bc chn khng ph thuc vo chn khng yu cu v tnh cht

ca hi. Thng thng, vi p sut vng bay hi ca thp yu cu l

25mmHg th vi h thng ht chn khng kiu vi phun hi th cn phi c ba

bc ht chn khng. S cu to v nguyn l hotng ca h thng to

chn khng c m t trong hnh H-5.37.

Hnh H-5.37. S Hthng ht chn khng vi thit b ngng t gin tip

c. L gia nhit

L gia nhit nguyn liu c cu to tng t nh i vi cc l gia nhit s

dng trong cc ng dng khc, v vy, trong khun kh bi hc hc ny khng

cp cu to chi tit ca l. Trong phn ny ch gii thiu cc ch hot

ng ca l lin quan n hotng ca thp chng ct L gia nhit nguyn



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liu ca thp chng ct chn khng c ba ch hotng gn cht vi ch

vn hnh v thit k thp. Cc ch ny bao gm:

- Ch hotng "kh": y l ch hotng vi nhit nguyn

liu c gia nhit nhit cao nht. Trong ch hotng ny,

hi nc khng c a vo nguyn liu trc khi vo l gia nhitcng nh dy thp chng ct.

- Ch hotng "t": y l ch hotng mnguyn liu c

gia nhit nhit thp nht. Trong ch hotng ny, hi nc

ng thi c a vo nguyn liu u vo l gia nhit v sc

y thp chng.

- Ch hotng trung gian (ch "m"): y l ch hotng m

nguyn liu cgia nhit nhit trung gian gia hai ch hot

ng trn. Trong ch hot ng ny, hi nc ch c a vo

nguyn liu u vo l gia nhit m khng c sc y thp

chng.

Vic thit k l gia nhit v thp chng ct vn hnh cc ch cn phi

c xc nh r rng ngay t u da trn c im ca nguyn liu v yu

cu vn hnh m bo thit k ng b gia cc thit b trong phn xng.

5.4.3. Cc qu trnh chng ct khc

5.4.3.1. Gii thiu chungNgoi hai qu trnh chng ct du th p sut kh quyn v p sut

chn khng c vai tr quan trng trong qu trnh ch bin du th v l nhng

qu trnh chng ct in hnh nht th trong cng nghip ch bin du kh cn

s dng thp chng ct phn tch cc phn on nhiu giai on ch

bin tip theo nh: qu trnh cracking, qu trnh x l bng hydro, qu trnh

reforming,... c im chung ca cc thp chng ct ny l phn tch hn hp

sau phn ng thnh cc phn on khc nhau c ng dng ring. Mi mt thp

chng ct ny c c im cu to v ch hotng ring ty vo ng dngc th. Di y s gii thiu mt cch khi qut v cc thp chng ct ny.

5.4.3.2. Thp ct trong qu trnh cracking

Cc thp chng ct l mt b phn quan trng cu thnh phn xng

cracking bn cnh b phn phn ng v ti sinh xc tc. S cng ngh

chung ca qu trnh cracking xc tc vi thit b chng ct c cp

trong mc II ca bi 1" Thit b phn ng" ca gio trnh ny. Trong phn ny

ch cp su hn v s nguyn l hot ng ca thp chng ct chnh, v



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cu to mt s b phn m khng cp n tng quan qu trnh cng ngh

cracking na.

a. S cng ngh ca thp chng ct chnh

S cng ngh ca phn xng cracking tng i phc tp vi nhiu

thp chng luyn ln nh v vi mc ch khc nhau. Trong khun kh ca bihc ny ch gii thiu thp chng ct chnh (main fractionator). Thp chng ct

chnh trong phn xng cracking c s ng dng cng ngh tng i phc

tp so vi thp ct du th p sut kh quyn do mi lin h phc tp gia

thp chng ct vi l phn ng v b phn thu gom v x l kh trong phn

xng. S cng ngh n gin ho ca thp chng ct trong phn

xng cracking c m t trong hnh H-5.38. Theo s cng ngh ny, hn

hp phn ng sau khi i qua hng lot cc thit b trao i nhit c a vo

thp chng ct. Ti y, hn hp sau phn ng cracking c phn chia thnh

cc phn on chnh. Naphtha nh v cc cu t hydrocacbon nh c tch

ra v ngng t mt phn nh thp. Phn lng c a sang phn xng

thu hi kh x l tip. Phn kh cha ngng t c a v ca ht my nn

t (Wet Gas Compressor). Phn on naphtha nng c tch ra thn thp

ri a qua thp sc lm sch sau c a ti b cha trc khi em

i x l. Thng thng, phn on naphtha chim mt t l tng i ln trong

tng s sn phm thu hi c sau qu trnh cracking. Phn on du nh tunhon (Light Cycle Oil-LCO) cng c tch ra thn thp chng ct chnh ri

a ra thp sc cnh thp. Thp sc c nhim v hiu chnh li khong ct

thch hp cho phn on naphtha trc khi a ti b cha (hoc a trc tip

ti phn xng ch bin pha sau). Phn on du nng tun hon (Heavy

Cycle Oil-HCO) c tch ra thn thp chnh nhm iu khin nhit

ca thp v mt phn c s dng lm du ra m khng c xem nh l

mt sn phm cui cng. Mt phn du nng tun hon s c a tr li l

phn ng tng hiu qu qu trnh cracking. Du cn (Decant oil) c tchra t y thp chng ct sau khi a qua mt lot cc thit b trao i nhit

(thit b tn dng nhit gia nhit cho nguyn liu hoc sn xut hi). Mt

phn du cn c a quay tr li l phn ng tng hiu sut thu hi sn

phm nh.

iu khin nhit ca thp, mt phn cc phn on tch ra c

a ti cc thit b trao i nhit nhm iu chnh nhit cht lng sau a

quay tr li thp chng ct. Vi mc ch tit kim nng lng, ngun nhit ny

thng c s dng gia nhit nguyn liu hoc sn xut hi nc. Ngoi



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ra, dng thit b lm mt bng khng kh cng c u tin s dng trong

trng hp iu chnh nhit thp tit kim nc lm mt, gim gi thnh

thit b v chi ph vn hnh.

Hnh H-5.38. S thp chng ct chnhtrong phn xng cracking (RFCC)b. Cu to v nguyn l hotng thp chng ct chnh

Thp chng ct chnh ca phn xng cracking c cu to tng i

phc tp. Thp s dng phi hp c dng a v dng m. Phn thp m

thng dng cho cc v tr cnrt cc phn on ra khi thp v ti phn phi

li lng trong thp. Nhit ca cc dng cht lng ly ra t thp c nhit

tng i cao, v vy trong phn xng b tr nhiu thit b trao i nhit v

thit b sn xut hi nc t trung p n thp p nhm tit kim nng lng.



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Cu to cc chi tit bn trong thp c trnh by mc 2, phn III ca bi

hc ny.

5.4.3.3. Thp chng ct trong phn xng khc

Cc thp chng ct trong mt s phn xng cng ngh khc nh

reforming, x l naphtha bnghydro, isome ho nhn chung tng i gingnhau v c mc ch v cu to. Cc thp chng ct ny c mc ch duy nht

l tch cc sn phm nh c hnh thnh trong qu trnh phn ng ra khi

sn phm chnh ca qu trnh phn ng. Chnh v vy, cc thpchng ct ny

ch c hai dng sn phm: Sn phm nh l kh ho lng v mt phn kh

nhin liu, sn phm y l sn phm chnh ca qu trnh phn ng (naphtha,

isomerate, reformate). Tng ng vi mc ch trn, cc cc thp chng ct

ny c cu to ngin hn, thng khng c cc ct sc bn cnh hay cc

bm tun hon cnh thp iu chnh nhit thp. S cng ngh chung

ca dng thp ny c m t trong hnh H-5.39.

Hnh H-5.39. S cng ngh cc thp n nh (stabilizer) tron

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