Giáo trình đường ống và bể chứa

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Mc lc Trang

TNG QUAN V BN CHA DU KH.................................................................3 1. Gii thiu...................................................................................................3 2. Phn loi bn cha du kh.......................................................................3

THIT K BN CHA...............................................................................................6 1. Xc nh cc thng s cng ngh bn cha .............................................6 2. La chn vt liu lm bn .........................................................................6 3. Xc nh gi tr p sut tnh ton ...............................................................7 4. Xc nh cc tc ng bn ngoi ..............................................................7 5. Xc nh chiu dy ca bn ......................................................................8 6. Xc nh cc l trn bn............................................................................8 7. Xc nh chn v tai nng....................................................................8 8. Cc nh hng thy lc n bn cha.....................................................8

THI CNG BN CHA............................................................................................11 1. Tng quan thi cng bn cha..................................................................11 2. Cc phng php thi cng nn mng .....................................................11 3. Cc phng php thi cng bn cha......................................................14 5. Trnh t thi cng bn cha ......................................................................19

CC THIT B PH TR BN CHA..................................................................22 1. H thng Bm.........................................................................................22 2. H thng van (valves) .............................................................................25 3. Dng c o..............................................................................................33

THIT K H THNG NG NG...................................................................45 1. Tng quan ...............................................................................................45 2. Thit k khi nim cho ng ng ..........................................................46 3. Thit k c kh cho ng ng ...............................................................55

QU TRNH XY LP NG NG...................................................................69 1. La chn v nh du tuyn ng............................................................69 2. Quyn vn chuyn v qu trnh ph hoang.............................................69 3. Qu trnh o rnh ..................................................................................70 4. Qu trnh ri ng v un ng...................................................................72 5. Qu trnh hn ng ...................................................................................73 6. Ph ng v h ng xung rnh ...............................................................75 7. Qu trnh lp rnh ...................................................................................76 8. Thi cng ti cc v tr ct ngang ng qua cc khu vc c bit................77 9. Cc v tr hn on ni ng......................................................................78 10. Phc hi trang thi ban u...................................................................79 11. Cc k thut c bit s dng trong thi cng ng ng......................79 12. S an ton ............................................................................................81

BO V V CHNG N MN CHO H THNG NG NG....................82 1. Phn loi n mn ....................................................................................82 2. Cc phng php kim tra v pht hin n mn ....................................87 3. Cc phng php bo v chng n mn ................................................91


Phn 1

K THUT BN B


Chng 1

TNG QUAN V BN CHA DU KH

1. Gii thiu Trong cng nghip ho du, tt c cc hot ng sn xut, bun bn, tn tr

u lin quan n khu bn b cha. Bn, b cha tip nhn nguyn liu trc khi a vo sn xut v tn tr

sau sn xut.

Bn cha c vai tr rt quan trng, n c nhim v: tn tr nguyn liu v

sn phm, gip ta nhn bit c s lng tn tr. Ti y cc hot ng kim tra cht lng, s lng, phn tch cc ch tiu trc khi xut hng u c thc hin.

Ngoi ra n cn c h tr bi cc h thng thit b ph tr: van th, nn mng, thit b chng tnh in, mi che

2. Phn loi bn cha du kh 2.1 Phn loi theo chiu cao xy dng

B ngm: c t bn di mt t, thng s dng trong cc ca hng

bn l.


B ni: c xy dng trn mt t, c s dng cc kho ln. B na ngm: Loi b c chiu cao b nh ln mt t, nhng hin nay

cn rt t. B ngoi khi: c thit k ni trn mt nc, c th di chuyn t ni

ny n ni khc mt cch d dng. So snh hai loi b ngm v b ni B ngm B ni An ton cao: y l l do chnh v bo

m phng chy tt v nu c r r th du cng khng lan ra xung quanh

t bay hi: do khng c gi, khng trao nhit vi mi trng bn ngoi

To mt bng thong

Chi ph xy dng thp Bo dng thun tin: d dng

sc ra, sn v sa cha b D dng pht hin v tr r r

xng du ra bn ngoi

2.2 Phn loi theo p sut

B cao p: p sut chu ng trong b > 200 mmHg B p lc trung bnh: p sut = 20 => 200 mmHg thng dng b KO, DO B p thng: p sut = 20 mmHg p dng b du nhn, FO, b mi phao.

2.3 Phn loi theo vt liu xy dng B kim loi: lm bng thp, p dng cho hu ht cc b ln hin nay. B phi kim: lm bng vt liu nh: g, composite,.. nhng ch p dng cho

cc b nh.

2.4. Phn loi theo hnh dng.

B tr ng: thng s dng cho cc kho ln.


B hnh tr nm: thng chn xung t trong ca hng bn l hoc ni

trong mt s kho ln.

B hnh cu, hnh git nc: cn rt t mt s kho ln.


Chng 2

THIT K BN CHA

Bn cha trong ngnh du kh ch yu dng cha cc sn phm nhin

liu nh: kh, xng, D.O, v cc nguyn liu ca ngnh ho du nh: VCM, butadiene,

Cc sn phm du kh c kh nng sinh ra chy n cao, mc c hi nhiu nn i hi vic thit k cng nh tnh ton phi ht sc cn thn. Cc h thng ph tr km theo phi c b tr cn thn, tnh ton t m, nht l h thng phng chy cha chy, b tr mt bng nhm hn ch ti thiu kh nng xy ra chy n cng nh khc phc khi xy ra s c.

Tuy nhin, vic tnh ton c kh cho bn cao p l quan trng nht v khi xy ra s c th vic khc phc ch mang tnh cht hnh thc, thit hi gy ra cho s c l kh lng.

Qu trnh tnh ton bn cao p bao gm cc bc sau:

1. Xc nh cc thng s cng ngh bn cha Cc thng s cng ngh ca bn bao gm: - Th tch ca bn cha V. - Cc kch thc c bn nh: chiu di phn tr (l), ng knh phn tr (d), chiu cao phn np bn cha (h), loi np bn cha.

- Cc thit b lp t trn bn cha, bao gm: cc valve p sut, cc thit b o p sut, o mc cht lng trong bn, o nhit .

- V tr lp t cc thit b trn bn cha. - Cc yu cu v vic lp t cc thit b trn bn cha.

2. La chn vt liu lm bn

Cc sn phm du kh cha trong bn thng c p sut hi bo ho ln, nhit ho hi thp v c tnh c hi.

Mc n mn ca cc sn phm du kh ny thuc dng trung bnh, ty thuc vo loi vt liu lm bn, nhit mi trng m mc n mn cc sn phm ny c s khc nhau.

Khi xt n yu t n mn, khi tnh ton chiu dy bn, ta tnh ton thi gian s dng, t tnh c chiu dy cn phi b sung m bo cho bn n nh trong thi gian s dng.

Vic chn la vt liu cn ph thuc vo yu t kinh t, v i vi thp hp kim c gi thnh t hn nhiu so vi loi thp cacbon thng, cng ngh ch to phc tp hn, gi thnh gia cng t hn nhiu, i hi trnh tay ngh ca th hn cao.

Sau khi la chn c vt liu lm bn, ta s xc nh c ng sut tng ng ca n, y l mt thng s quan trng tnh ton chiu dy bn. i vi


cc loi vt liu khc nhau th ng sut khc nhau, tuy nhin cc gi tr ny khng chnh lch nhau nhiu.

3. Xc nh gi tr p sut tnh ton

y l mt thng s quan trng tnh chiu dy bn cha. p sut tnh ton bao gm p sut hi cng vi p sut thy tnh do ct cht lng gy ra:

Ptt = Ph + g H Trong :

Ptt: p sut tnh ton. Ph: p sut hi. : Khi lng ring sn phm cha trong bn nhit tnh ton. g = 9.81 (m/s2): gia tc trng trng. H: Chiu cao mc cht lng trong bn.

Thng ta tnh chiu dy chung cho c bn cha cng chu mt p sut (ngha l p sut tnh ton chung cho c bn cha).

i vi cc sn phm du kh cha trong bn cao p, p sut tnh ton thng c gi tr:

- Propan : 18 (at) - Butan : 9 (at) - Bupro : 13 (at)

4. Xc nh cc tc ng bn ngoi Cc tc ng bn ngoi bao gm:

4.1 Tc ng ca gi Gi c th tc ng n bn, nh hng n n nh ca bn, lm cho bn

b un cong hay tc ng n hnh dng ca bn. Tuy nhin i vi bn cao p, do hnh dng cng nh cch t bn nn nh hng ca gi tc ng ln bn nh. nh hng gi c th b qua nu nh ta xy tng bo v hoc t bn v tr kn gi.

4.2 Tc ng ca ng t

y l tc ng hy hu, khng c phng n chng li. Tuy nhin khi xt n phng n ny, ta ch d on v ch m bo cho cc sn phm khng b tht thot ra ngoi, nhng vic ny cng khng th chc chn c. Phn ln cc tc ng ny ta khng th tnh ton c v s phc tp ca ng t. Tc ng ny gy ra hin tng trt bn ra khi chn , cong bn, gy bn. Tt nht ta chn khu vc n nh v a cht xy dng.

- Cc ti trng tc ng ln n c th xy ra cng c xt n, chng hn nh cc thit b b tr trn thn bn: h thng cc thit b km theo, cu thang, gin ,Cc ti trng ny c tnh ton trong phn tnh ton bn.


- Ngoi ra cn xt n cc yu t bn ngoi do con ngi tc ng nh: o t, cc hot ng c th gy ra va p vi bn, cc hot ng mang tnh cht ph hoi. Chnh cc yu t i hi ta phi c cc phng n bo v thch hp nh thng xuyn kim tra, xy tng bo v, c cc k hiu cho bit y l khu vc nguy him, c th gy ra chy n ln v nh hng n cc vng ln cn, ng thi phi c nhng quy nh, ch ti c th i vi ngi vi phm.

5. Xc nh chiu dy ca bn

Cng vic xc nh chiu dy ca bn c thc hin theo cc bc sau: Xc nh tiu chun thit k: ASME section VIII.Div.1 Xc nh c ng sut cho php ca loi vt liu lm bn cha: cp Xc nh p sut tnh ton bn cha: Ptt Xc nh h s b sung chiu dy do n mn C = Cc + Ca Cc thng s cng ngh nh: ng knh bn cha (D), Chiu di phn

hnh tr (L). Cc thng s v np bn cha: Loi np bn cha, chiu cao np bn cha.

6. Xc nh cc l trn bn i km vi bn l h thng ph tr bao gm c cc ca ngi, cc l dng

lp cc thit b o nh nhit , p sut, mc cht lng trong bn, cc l dng lp t cc ng nhp liu cho bn, ng xut liu, ng vt bn, lp t cc valve p sut, cc thit b o t nng hi sn phm trong khu vc bn cha.

Cc thit b lp t vo bn c th dng phng php hn hay dng ren. Thng i vi cc l c ng knh nh ta thng dng phng php ren v d dng trong cng vic lp t cng nh trong vic sa cha khi thit b c s c.

Khi to l trn bn cha cn ch n khong cch gia cc l cng nh vic tng cng cho l.

7. Xc nh chn v tai nng

Chn bn cha ta dng chn bng thp hn hay c th xy bng gch,

btng. Tuy nhin, trong ngnh du kh ta thng dng chn bng thp hn. Ta chn vt liu lm chn , cc thng s chn sau kim tra bn.

Cc yu cu khi kim tra bn: - Gi tr ng sut m ti trng tc dng ln gi khng ln hn 2/3 gi tr

ng sut vt liu lm chn . 8. Cc nh hng thy lc n bn cha

8.1 p sut lm vic cc i

L p sut ln nht cho php ti nh ca bn cha v tr hot ng bnh thng ti nhit xc nh i vi p sut . l gi tr nh nht thng


c tm thy trong tt c cc gi tr p sut lm vic cho php ln nht tt c cc phn ca bn cha theo nguyn tc sau v c hiu chnh cho bt k s khc bit no ca p thy tnh c th tn ti gia phn c xem xt v nh ca bn cha.

Nguyn tc: p sut lm vic cho php ln nht ca mt phn ca bn cha l p sut trong hoc ngoi ln nht bao gm c p sut thy tnh nu trn cng nhng nh hng ca tt c cc ti trng kt hp c th xut hin cho vit thit k ng thi vi nhit lm vic k c b dy kim loi thm vo bo m n mn .

p sut lm vic ln nht cho php c th c xc nh cho nhiu hn mt nhit hot ng, khi s dng ng sut cho php nhit .

Th nghim p sut thy tnh c thc hin trn tt c cc loi bn sau khi tt c cc cng vic lp t c hon tt tr cng vic chun b hn cui cng v tt c cc kim tra c thc hin tr nhng yu cu kim tra sau th nghim.

Bn cha hon tt phi tha mn th nghim thy tnh. Nhng bn thit k cho p sut trong phi c th p thy tnh ti nhng

im ca bn c gi tr nh nht bng 1,5 ln p sut lm vic ln nht cho php (p sut lm vic ln nht cho php coi nh ging p sut thit k), khi tnh ton khng dng xc nh p sut lm vic ln nht cho php nhn vi t s thp nht ng sut S nhit th nghim v ng sut S nhit thit k.

Th nghim thy tnh da trn p sut tnh ton c th c dng bi tha thun gia nh sn xut v ngi s dng. Th nghim p sut tnh ti nh ca bn cha nn l gi tr nh nht ca p sut th nghim c tnh bng cch nhn gi tr p sut tnh ton cho mi thnh phn p sut vi 1,5 v gim gi tr ny xung bng p sut thy tnh ti . Khi p sut ny c s dng ngi kim tra nn i hi quyn c yu cu nh sn xut hoc nh thit k cung cp cc tnh ton c s dng xc nh p sut thy tnh bt k phn no ca bn cha .

Bung p sut ca nhng thit k kt hp c thit k hot ng c lp phi c th nh mt bn cha ring bit ngha l tin hnh th vi bn bn cnh khng c p.

8.2 Ti trng gi

Ti trng gi bt buc phi c xc nh theo nhng tiu chun, tuy nhin nhng iu lut ca quc gia hoc a phng c th c nhng yu cu khc khe hn. Nh thu nn xem xt mt cch k lng xc nh yu cu nghim ngt nht v s kt hp yu cu ny c c chp nhn v mt an ton, kinh t, php lut hay khng. Gi thi bt k hng no trong bt k trng hp bt li no u cn phi xem xt.

8.3 Dung tch cha ln nht cho bn mi ni

Khong 85 90% dung tch ca bn mi ni c s dng trong iu kin bnh thng, phn th tch khng s dng l do khong cht trn (dead space) nh v khong cht di (dead stock) y.


i vi bn mi ni, chn chiu cao bn t sc cha ln nht. Khong cht trn v cht di chu nh hng nhiu bi chiu cao hn l ng knh, do cng vi mt th tch th bn cao cha nhiu hn bn thp.

Chiu cao ln nht t c c xc nh bi iu kin t ai ni t bn. Do , khi chn v tr t bn cha phi iu tra v lnh th ni t bn.

Do khong cht trn nn b khng c cha y, nu qu nh mc th s c bo ng bi n bo ng mc high level.


Chng 3

THI CNG BN CHA

1. Tng quan thi cng bn cha

Nn bn cha phi c thit k nh mt chn do dai, vi bn thch hp m bo rng nn c th chu c s phn b mt cch hp l p lc khng cn bng trn nn. S bin dng ca nn di mt mc nht nh, to ra mt nn mng c bn thch hp. Cn phi loi tr s ln qu ln v ln khng ng u. Mi quan h gia cng ca v bn vi y bn v nn t cn quan tm.

nghin c th c cung cp di v bn. Nhng vt liu ny gip chng li ng sut ct cng nh s ph hy trong sut qu trnh xy dng.

C 2 loi bn chnh l bn s dng trong trng hp sc gi mnh v bn p thp c tnh n sc gi c k hiu HBC v BHD.

B rng ca vai c chn ty thuc vo tnh n nh ca nn vai v nn c m bo kch thuc b rng vai nh nht nn l 1m cho bn cha cao 15m v 1,5m cho bn cha cao trn 15m.

S phn tch nn bn cha cn c tnh thm kh nng tc ng ca gi, ng t, cc cht cha trong bn. Kh nng trt ca t cn c nghin cu k.

nhng vng tnh trng v t cha c hiu bit mt cch cn k th nn gia tng chiu cao ca bn cha theo tiu chun c tnh n s nghin ln.

i vi nhng khu vc c iu kin tht thng hay mc nc ln xung tht thng, khu vc ng bng vnh cu th phi s dng cc kt cu c bit ring.

2. Cc phng php thi cng nn mng

Cc tiu chun v nn mng c xem xt ph hp vi tt c sn phm thng thng s cha trong bn c trn th trng v kho cha k c du bi trn, nha ng vi nhit thay i. i vi nhng b cha LPG th c nhng tiu chun ring.

Hin tng ln khng u ca bn mi ni do hin tng bp mo ca bn, iu ny lm h hng c cu bt kn. Loi ny c th xy dng trn nn t bnh thng (hoc ngay c yu), mt s trng hp ngi ta s dng phng php d phng l dng mt lp nghin nh hay vng c gia c bng b-tng pha di kt cu bn. Trng hp ny cng dng cho bn mi c nh.

Cn c h thng thot nc pht hin r r trnh s tch t nc to nn p lc c th ph hy lp bao ph nn mng. Vi lc c s dng di lp


bao ph ca vai v ng dc ca vai ni m kh nng xi l nhng vt liu mn hin hu c th xy ra.

Mt vng kim loi t di ngay nhng ch chu lc ct ca kim loi xung quanh chu vi bn.

Xung quanh chu vi bn c bitume rng 150 mm dng lm m v chng thm.

B c gia c v b ngoi c ph bi ming b-tng dy t nht 50 mm chng thm.

Cc bc tin hnh c bn trc khi thi cng nn mng bao gm:

2.1 Kho st v tr Nh ngi t vn a cht ng tin cy kho st vng t (hiu r t ai

a phng, c kinh nghim v vic t nn mng). y l bc quan trng, nh hng sut qu trnh thi cng.

2.2 Kim tra t

Ngi ta thng dng php th thm hnh nn ca Dutch (DCTPs): nhng l khoan thay th hay php th thm tiu chun (SPT) s c chp nhn nu nhng php th DCPTs khng kh thi. Nhng php th trong phng th nghim trn nhng l khoan s xc nh tnh cht vt l, c hc v ha hc ca t nhng a im v su khc nhau.

Tng qut, s ln php th DCPTs s c tin hnh trong phm vi 1m xung quanh nn mng b, i vi b c ng knh c 15m hay nh hn, ch cn tin hnh 1 php th gn khu trung tm ca nn mng v 1 hoc 2 l khoan ph. Chiu su ca php th DCPTs s ph thuc vo ng knh b cng nh iu kin t nhin ca t. Vn c bit quan trng khi ng knh ca b ln, bi v s gia tng ng knh b s to ra mt nh hng rt ln ln lp t bn di b.

S ln ti thiu ca nhng php th DCPTs: 3DCPTs i vi b c ng knh 15m 5DCPTs i vi b c ng knh 50m 9DCPTs i vi b c ng knh > 50m su c xuyn qua khong gia c th t 3-5m di sn ca nn

mng, xc nh bn cht ca nn t ngay di nn mng.

2.3 Vt liu thi cng nn mng Hn hp bitume-ct cho b bn cha: Ct sch v lng bn t hn 5%. Lng nguyn liu chy qua ry 200

mesh nn t 3-5% (iu ny c th t t nhiu ngun pha trn khc nhau), nhng hn hp yu cu c th c to thnh t nhiu loi ct vi nhiu kch c khc nhau.

Mt s loi bitume thch hp cng vi khong nhit


Loi Khong nhit Shelmac50/100 65-95 Shelmac150/200 80-95 Shelmac200/300 85-105 Shelmac300/400 95-110 Shelmac400/500 100-115 Shelmac500/700 110-120 Shelmac S.125 150-135 Shelmac SRO 70-100 MC 800 80-115 MC 3000 95-120 MC 3 65-95 MC 4 80-100 MC 5 100-120 Mexphalte 80/100 135-160 Mexphalte 60/70 145-170

Cc loi my trn bitume-ct c th trn lin tc hay gin on, trong mt

vi trng hp phi trn bng tay mc d chng ch c th thc hin khi hn hp c chnh xc cao. Ct phi c lm kh trn a thp bng la v bitume phi c nung trc khi trn vi nhau bng xng.

Hn hp bitume-ct c th c ri bng tay, nhng phn ln thi cng u s dng thit b chuyn dng. B dy hn hp thng dng l 50 mm.

Hn hp ct phi d dng lin kt v dng thit b lp bm hi c trc ln hoc my ko ln qua li thc hin qu trnh kt dnh, dng thm my ko lp st nhm y mnh qu trnh lin kt.

Hn hp ct t cho vai ca : Ct khng nn cha hm lng bn ln hn 3%. Hn hp tha mn khng

i hi gii hn cp , do hn hp c trn t nhiu ngun ct c cp rng. Tuy nhin, hn hp mong mun nn t 3-10% i qua ry 200mesh.

Bitume l mt phn on kerosen c bit c pha ch sn vi tn thng mi l Shelmac SRO (Special Road Oil) vi nht t 40-50s STV(Standard Tag Viscocity) 250C. i vi iu kin nhit i, thng s dng bitume cng hn vi tn Tropical SRO, c th t hng t nh my lc du Shell.

ph ln ct t ta cn thm vo cht hot ha to lin kt vi ph gia cha trong SRO. Cht hot ha hiu qu nht l Ca(OH)2 vi hm lng khong 90%. Mc d ch mt s lng t cn thit cho phn ng ha hc, nhng trn 2% tng khi lng hn hp c dng m bo phn tn tt trn ct. Xi mng Porland thng c thay th vi hm lng t 3%-4% do xi mng c khi lng ring ln. Cht hot ho c phn tn vo ct trc khi vi SRO. Lng cht hat ha khng nn dng vi lng ln hn do n khng dng cho phn ng ha hc, lc s cn lng SRO thm vo do cht hat ha c b


mt ring ln v ngoi ra n c th gy gim kh nng bn c lm hn hp dn v d v hn.

Nc l thnh phn khng th thiu v thm ch ngay vi ct m th cn phi thm nc sao cho hm lng ca n ti thiu l 5%.

Hm lng SRO nh nht c quyt nh bi vic kim tra n gin kt dnh. Mt hn hp c thnh phn: ct kh, 4%SRO, 2%Ca(OH)2 v 10% nc c trn bng tay. Ni chung, hn hp trn t hm lng SRO thch hp th thng t yu cu, nhng cng phi ch mt s iu kin trnh xy ra s khng ng cng ca hn hp do tnh khng thm nc s ngn s ha hi ca nc v dung mi. iu ny thng xy ra i vi nhng cp mn hay ct b d i hi hm lng SRO cao. Do phi kim tra bng cch ln trn mt ci khay, nu hn hp c tnh thm th hn hp c ln trc s bay i. Nu nh nc khng bay hi th hn hp em th s khng c tnh thm nc v phi loi b. Hn hp c em s dng v nn cht bng nhng phng php tng t nh i vi hn hp ct kh v bitume. 2.4 ca bn cha

c dng gi sn phm trong khu vc c chn v ngn khng cho sn phm trn ra nhng khu vc xung quanh. Trong khong gia ca yu cu phi cc bc tng btng hay . Trong mt s trng hp khi khng kh nng cha lng yu cu th thm vo nhng ch trng.

Thit k ca Tng thng c gia c bng b-tng, gch hay . Trong nhng

trng hp phi quan tm t bit n mi ni m bo chng c cht. Quan tm n kh nng r r xuyn qua hoc bn di tng , ph thuc nhiu vo lp mt t v lp t ngay bn di ch xy tng.

Sn Nn cha cht xp, vi khu vc c mc nc thp nht khng cn thit

phi chng thm ra xung quanh vic r r chp nhn c. Ni c r r cao hay cc vng ln cn c th b nhim th cn ra phng n chng thm. Vn quan tm l kh nng chng thm khu vc c ma ln hay ni tn tr khng c ngi. Trng hp th mc thm nh hng quan trng n nn mng ca bn v tng t ca do chng bo ha vi cht lng to nn s phn r, xi l nhng l hng trong nn . 3. Cc phng php thi cng bn cha

i vi bn hnh tr, qu trnh dng bn c th tin hnh vi nhiu phng

php khc nhau. Khng b buc mt phng php c th no i vi cc loi bn khc nhau. Tuy nhin i vi cc nh thu vy dng thng c kinh nghim, ng vi mt trng hp c th h s a ra mt gii php thch hp ty thuc vo qu trnh ti u ha v mt nhn cng v trnh k thut tay ngh


ca i cng nhn. Nhim v ca h l a ra mt quy trnh xy dng hon thin mang tnh kh thi, tho ng v c kh nng mang li mt kt qu tt.

dng mt bn cha cht lng mang tnh m quan c kh nng trnh c hin tng mp v mo bn, tnh ng n ca quy trnh hn cn c tun th i km vi qu trnh gim st nghim ngt.

V th, hn ch ti a cc hin tng xu c th xy ra trong qu trnh xy dng, trc tin nh thu phi cn nhc k lng la chn phng php xy dng hp l m bo mang li mt kt qu tho mn.

3.1 Phng php hn hon thin v ghp dn (Progressive Assemply and Welding)

Trong phng php ny, trc tin cc tm thp dng gia cng mt y

c lp ghp v hn li vi nhau. Theo sau l qu trnh gia cng thn bn. Quy trnh c tin hnh tng tng mt, cc tm thp c un cong, t ng v tr, kp cht vi tng bn di bng cc inh ghim sau th tin hnh qu trnh hn cc tm thp li vi nhau cho n khi hon chnh hon ton mi ghp tng ang gia cng. C th cc tng thp ln lt c chng ln cao cho n nh.

Cui cng l cng on lp khung mi v mi bn trn

3.2 Phng php hn gin on v lp ghp tng th (Complete Assembly followed by Welding of Horizontal Seams)


Phng php ny tng t nh phng php trn, trc tin cc tm thp

c tp hp gia cng y. Tip theo l qu trnh gia cng thn bn. Cc tm ghp c un cong, t ng v tr v kp cht, nhng y ch hn trc cc mi ghp dc, v gi nguyn cc mi ghp ngang. C th sau khi hon thin tng thp ban u tip tc n cc tng thp bn trn v cho n tng thp cui cng.

Tip theo l qu trnh lp ghp khung mi v mi bn. Sau cng cc mi ghp ngang thn bn mi c hn hon thin hon

ton cc mi ghp thn bn. Quy trnh ny c th thc hin t trn xung hay t di ln

3.3 Phng php nng kch bn (Jacking-up Method)

Trong phng php ny, sau khi y bn c gia cng xong, tin hnh gia cng tm thp trn cng, sau lp rp gin mi v hn mi v np vi nhau. Qui trnh hn c thc hin trn y bn, cc b phn c thng qua cc con i. Sau khi tng thp trn cng ni vi np c hon thin xong, ngi ta kch cc con i nng chng ln mt cao va v chn vo cc tng thp bn di, tin hnh qui trnh hn hon thin. Sau khi tng thp c hon tt xong, cc tng thp bn di tip tc ln lt cho n khi hon thin xong tng thp di cng. Cui cng l cng on hn n vi y.

u im ca phng php ny l khc phc cc kt qu xu khi va thi cng xong, c bit l hin tng mp bn.

3.4 Phng php ni ( Floation method)


Phng php ny p dng cho cc loi b ni. Trong giai on u, qu trnh c tin hnh tng t nh phng php hn hon thin v ghp dn cho n khi hai tng thp ban u c gia cng xong. Dng thit b nng a mi ni gia cng xong vo bn trong. Sau , nc c bm vo bn, mi ni dng ln n mt v tr cn thit. Ngi ta dng n nh mt sn nng cng tc hu hiu cho qu trnh thi cng. Ngoi ra, mt cn trc nh di ng cng c dng trn mi n cu vo ng v tr cho qu trnh hn. C mi khi mt tng thp c hon thin xong, ngi ta li bm nc vo bn d thao tc cho cc tng thp bn trn.

Phng php ny ch c kh nng p dng ti cc cc khu t c kh nng chng ln cao v tin on c kh nng chng ln ca n. 4. Cht lng mi hn

Cht lng ca mi hn rt quan trng, n nh hng rt ln n cu trc

ca bn, qu trnh vn hnh v ti th ca bn. Cht lng ca mt mi hn ph thuc vo rt nhiu nguyn nhn, trong c cc nguyn nhn chnh sau:

4.1 Trnh ca cc th hn

Khi hn cc tm ghp bn, khung mi st, cu trc, khung trong qu trnh thi cng bn th phi c thc hin bi nhng ngi th c tay ngh, c chuyn mn k thut v c nhiu kinh nghim trong ngh. H phi vt qua c mt k thi kim tra trnh theo tiu chuyn quc t v h phi c bng cp, giy chng nhn v k nng, trnh hn.

Trong qa trnh hn tm hay hn c nh i vi y bn, v bn, mi bn phi c sp xp sao cho gim thiu ti a gy ra nguyn nhn gy bin dng v mp bn do mi hn gy ra.

Trong qu trnh hn y bn c th hn hoc khng hn tm kim loi vnh khuyn di y bn. Mc ch chnh ca nhng tm kim loi ny l chng thm

4.2 Cht lng ca qa trnh hn

Ch u t trong qu trnh lp ghp phi c nhim v kim tra quy trnh hn ca mnh xem c ph hp vi nhng tiu chun quy nh hay khng (shell). Ngoi ra, kim loi hn cng c kim tra cc thng s nh tc ng nhit hay tc ng lc theo tiu chun quy nh .

4.3 iu kin thi tit

Qu trnh hn khng nn tin hnh trong iu kin thi tit m t hoc ma gi, bo, tuyt, ma , v.v.tr khi ngi hn v qu trnh hn c che chn cn thn .

Khng nn tin hnh hn khi nhit mi trng qu thp (nh hn -18oC). Trong trng hp ny, trc khi hn phi gia nhit trc c hai ch ni ca nhng tm kim loi nn. Trong sut qu trnh hn cc lp th nhit gia nhit gia tng lun c duy tr trong 1 phm vi nht nh. i vi thp carbon


hay thp c ng sut trung bnh v cao u phi c gia nhit trc theo nhng quy nh nht nh .

4.4 in cc hn v dy hn

Vt liu hn phi c trong danh mc cho php vi cc vt liu hn m cc t chc c chc nng quy nh (mang tnh quc t).

in cc hn phi c bo qun, gi gn trong thng carton hay nhng ni kh ro trnh b tc ng xu ca mi trng.

Nu nh in cc hn b m t nhng khng h hi g th vn c th dng li khi c s ng ca nh sn xut in cc.Bt k in cc no b mt lp v bo v hay h hi th u phi b loi b. Nhng in cc c bn hoc in cc cha t Hydrogen s c dng cho nhng lp hn nn, iu ny l bt buc khi b dy ca tm kim loi >19mm hay nhit mi trng thp. in cc thp Hydrogen phi c bo v kh ro trong sut qu trnh hn, y l yu cu ca nh sn xut. in cc thp hydrogen c dng khi hn tay nhng kim loi c ng sut trung bnh cao.

4.5 Vt mp mi hn

i vi qu trnh hn t ng th vic chun b mp hn phi c tin hnh theo quy nh chun tu thuc vo b dy v kim loi ca vt liu lm bn

4.6 Trnh t hn

Hn tm thi c ng dng khi hn dc cc mi ni gia cc tm bn v nhng mi hn ngang gia hng cui ca v bn vi y bn trong sut qu trnh lp t bn, nhng sau n phi c loi b m khng li du vt g khi tin hnh hn c nh.

Khi thi cng bn b th phng php hn t ng c p dng vi nhiu u im :

- Nng sut hn t hiu qu cao . - Mi hn ng u v t gp nhng li do thao tc tay ca con ngi

gy ra (ln x,l xp) - Tit kim c vt liu hn - To c s kt lng ng u gia kim loi nn v kim loi hn,

do mi hn c m bo c tnh c, l, ha. - Gim c chi ph nhn lc v nhng thit b ph i km

i vi thi cng bn b th ch yu c hai mi hn l hn dc v hn ngang.

Trong nhng mi hn gm nhiu lp, mi lp hn ca kim loi hn u phi c lm sch x v nhng cht kt lng khc trc khi tin hnh hn lp tip theo. Mi hn c xem nh hon tt khi mi hn c lm sch. Phi lm v sinh cc lp x, cc cht bn bm bn ngoi trc khi c kim tra v qut sn.

Trong sut qu trnh hn phi c s tng i gia tc hn v cht lng ca mi hn. Mi mi hn cn c thi gian kim loi hn v kim loi nn chy ra, lng kt hiu qu nht (gim ti thiu nhng ng sut ni bn trong


mi hn ) m bo cc tnh cht kim loi ng t l tng ng vi vt liu nn ban u. 5. Trnh t thi cng bn cha 5.1 Chun b thi cng ( Prefabrication)

i vi v tr t bn nguy him hoc nm gn cc bn hin hu ang tn tr cc sn phm nh. V l do an ton, bn c th c gia cng trc v sau c vn chuyn n cng trng thi cng bng mt trong cc phng php sau: Gia cng bn trc ti cng xng (kch thc ti a ca bn ph thuc vo gii hn v kh nng ca phng tin vn chuyn, Thng thng gii hn ng knh ti a l 12m) v gia cng bn trc ti mt v tr tm thi an ton nm gn v tr t bn. Sau bn c vn chuyn n cng trng thi cng bng cn cu, xe ln hoc vng m kh.

Cn lu tin hnh qu trnh th thu lc sau bn c c nh ti v tr xc nh.

5.2 Quy trnh thi cng bn

H ging chng gi Trong qu trnh xy dng, bn phi c bo v c kh nng chng li

s bin dng hoc cc h hi c kh nng xy ra do p sut tc ng bi gi bng cc loi cp neo hoc ct chng thch hp. Cc neo phi c c nh vng chc trong sut qu trnh thi cng cho n khi bn c hon chnh mi hn thn my v khung mi, i vi bn np h phi i cho n khi dm chng gi c hon thnh. Cn quan tm n n nh vng chc ca mu neo cho cp khi cng trng thi cng tm ngh vo cui tun hoc ngy l, t bit lu i vi cc loi t bn yu. Cp c b tr vi yu cu ti thiu mt cp mi 8m quanh chu vi bn.

i vi khu vc c gi mnh, phng php ni l mt phng php hiu qu n nh, bo v bn trong qu trnh thi cng. V l do ny, phng php ngoi p dng cho cc bn np ni cn c th p dng linh ng xy dng cc bn h v bn np c nh.

Ph tng ph tr: Gi , ai c, kp ghim v nhng thit b b tr trong qu trnh xy dng

c th c hn gn vo thnh bn nhng khi hon tt qu trnh gia cng th phi tho g cc linh kin ny nhng khng c dng c o, km ko hoc git mnh cc b phn ny ra. Sau tin hnh gia bng cc phn kim loi nh ra do vt liu hn v lm sch b mt bn khi x hn. Khi pht hin cc ch lm phi dng cc vt liu cng bn cht hn nng chy in y ch khuyt v sau dng gia san bng.

Qu trnh gn tng thp ban u vo y bn:


Trong qu trnh ny cn lu n khe h cho php gia hai b mt thn v y bn b tr vi hin tng co gin ca kim loi khi hn v di tc ng ca mi trng. Sau khi cc tm thp c un cong v t vo ng v tr, thn bn c i kim tra tnh trn u ca thn. Trc khi c hn dnh vo y, cn s dng kp kim loi gi cc tm thp ng v tr v cc thit b h tr khc gn vo y bn bo m tnh chnh xc sau khi i trong sut qu trnh hn.

Kim tra tnh u n: Trc khi hn cc tm thp li vi nhau ( khi hon thnh tng di cng

ni vi dy), cn kim tra tnh iu n thng hng v tn ti khe h hp l gia cc tm thp, bt c s sai lch no xc nh c sau qu trnh hn phi nm trong khon dung sai cho php. Nu ta tin liu c cc gi tr sai lch vt qu khon ga tr cho php th phi tin hnh cn chnh li cc tm thp trc khi qu trnh hn c bt u.

Phi tht s cn trng, phi hp hiu qu cc qu trnh chun b trc vi qui trnh hn bo m hnh dng trn u ca ng knh v gim thiu s bin dng trong sut chiu di bn t y n nh bn. Nh u t c quyn t chi tip nhn bn chuyn giao khi pht hin bn c du hiu b on, mp hay bt c s bin dng no khc. Khi bn c hon thnh, khng c php nng chnh bn bng phng php gt ta t s u n trong mi trng hp.

Sau khi tng mt c dng ln v hn xong, sai lch ca bn knh trong c xc nh t tm bn n bt k im no thnh trong ca bn so vi bn knh danh ngha khng c ln hn cc gi tr so vi ng knh bn

D12.5m =13mm 12.5 45m =25mm

Khung v mi tn lp mi: Trc tin phi kim tra c th s ln ca bn v nn chnh thn bn t

c hnh dng yu cu trc khi dng khung mi v cc tm lp mi. Cc ct chng c dng ln tm thi lm chn cho qu trnh lp rp khung mi. Nh thu xy dng phi tnh ton ti trng ti a m cc ct phi chu tc ng. Sau tu theo kh nng chu lc ca tng loi ct m tnh ton ra s ct v b tr i xng nhng v tr thch hp. Khi cc ct dng xong, x dm hng tm, n tay v cc h ging ng v ngang c dng ln, cn lu v tr ca cc thanh ging phi c lp rp chnh mi c hnh dng cn xng v khng lch vi thn bn. Hon tt cng on ny thng qua qu trnh hn cc b phn li vi nhau. Sau c th tho ct v tin hnh qu trnh gia cng i vi tn lp mi.

Trong qu trnh tp hp, b tr v lp rp cc tm lp li vi nhau cn sp xp sau cho chng c sp xp di xng vi nhau qua tm bn. Mc ch ca qu trnh ny l ti trng phn b i xng qua khung mi tc ti trng phn


b u xung quanh mng bn. Khi ti trng phn b khng u th s dn n ng lc tp trung ti mt v tr rt d dn n hin tng nghing bn khi qu trnh ln xy ra. Sau khi cc tm thp c cn chnh xong c th tin hnh qui trnh hn dnh vo khung mi.

5.3 Cc phng php di chuyn bn

Di chuyn bn trn con ln: di chuyn bn trn nhng con ln, trc ht cn phi nng bn ra

nhng nn mng tm thi xung quanh chu vi ngoi bin 6m. Mt h thng ng ray bng st, c bi trn bng m, thch hp vi ton b chiu di on ng, v hi nghing v pha nn mng mi. Nhng con ln bng thp nm trn ng ray s nng ton b bn trong sut qu trnh di chuyn .

Khi bn nm trn con ln th n c y bng ti hay my ko. Khi n v tr mi, n s c nng ln li, h thng ray pha di s c loi b, sau bn c h n v tr mi. Trong qu trnh di chuyn th bn phi c kim tra gim st cht ch, trong nhng iu kin thi tit tht thng ma gi th khng nn thc hin, ng thi phi c bin php bo v bn bng cc h thng dy ai v dy neo.

Di chuyn bn bng phng php ni: Phng php ny c thc hin bng cch o con mng theo l trnh,

sau mng c lm y nc vi mt su thch hp bn c th ni khi nn mng ca n. Bn c lm ni, c y i n nn mng chun b ti v tr mi v cho php t n nh tr li khi ta tho nc ra khi mng.

V d nh vi bn c ng knh 36m, chiu cao 12m th c th ni trn con mng vi chiu su 600mm. Khi bn ni c th c y bng ti hoc may ko, s dng h thng ring bit dy cp n nh n trong qu trnh di chuyn.

Trong qu trnh di chuyn i vi bn np c nh c th di tr mt p lc ti a l 20 mbar trong bn nhm trnh c p lc nc gy ra khi bn ni.

gi c v tr vung gc vi mt nc trong khi di chuyn ngi ta c th hn ch bng cch thm ci ti ng ct vo di y bn

Phng php ny cng khng nn tin hnh trong iu kin thi tit ma gi.

Di chuyn bn bng m khng kh: Hiu qu ca phng php ny da trn tnh l lng nhm lm gim trng

ti ca bn trong qu trnh di chuyn. Mc khc phng php ny lm gim ti a chi ph, khng cn phi tn nhng chi ph lm ng st hay o . Trong phng php ny, bn c th di chuyn hay quay mt cch d dng. Vi cc on ng c tnh trng thng thng th khng c vn g xy ra, khng cn phi sa sang li on ng di chuyn, m mc chnh xc t bn rt cao.

Sau khi bn c di chuyn n nn mng mi bi mt trong ba phng php trn, th cc mi hn y bn phi c kim tra li v ng sut v r r.


Chng 4

CC THIT B PH TR BN CHA

1. H thng Bm

1.1 Bm ly tm

Bm ly tm lm vic theo nguyn tc ly tm. Cht lng c ht v y cng nh nhn thm nng lng (lm tng p sut) l nh tc dng ca lc ly tm khi cng gung quay. Bnh gung c t trong thn bm v quay vi vn tc ln. Cht lng theo ng ht vo tm gung theo phng thng gc ri vo rnh gia cc cng gung v chuyn ng cng vi gung. Di tc dng ca lc ly tm, p sut ca cht lng tng ln v vng ra khi gung theo thn bm (phn rng gia v v cnh gung) ri vo ng y theo phng tip tuyn. Khi tm bnh gung to nn p sut thp. Nh lc mt thong b cha (b h p sut kh quyn), cht lng dng ln trong ng ht vo bm. Khi gung quay, cht lng c ht v y lin tc, do cht lng chuyn ng rt u n. u ng ht c li lc ngn khng cho rc v vt rn theo cht lng vo bm gy tc bm v ng ng. Trn ng ht c van mt chiu gi cht lng trn ng ht khi bm ngng lm vic. Trn ng y c lp van mt chiu trnh cht lng khi bt ng dn v bm gy ra va p thu lc c th lm hng gung v ng c in (khi gung quay ngc do bm bt ng dng li). Ngoi ra trn ng y cn lp thm mt van chn iu chnh lu lng cht lng theo yu cu. Bm ly tm lc khi ng khng d ui ht khng kh ra khi bm v ng ht, to ra chn khng cn thit. V vy, trc khi m my bm, phi mi cht lng vo y bm v ng ht hoc c th t bm thp hn mc cht lng trong b ht cho cht lng t ng chon y thn bm.

p sut ca cht lng do lc ly tm to ra hay chiu cao y ca bm ph thuc vo vn tc quay ca gung; vn tc cng ln th p sut v chiu cao y cng ln. Tuy nhin, khng th tng s vng quay bt k c, v lc y ng sut trong vt liu lm gung s tng v ng thi tr lc cng tng cng vn tc. Do d bm mt cp ch t c p sut ti a 40 n 50m, cn mun tng p sut cht lng ln hn na th phi dng bm nhiu cp.


Bm ly tm 1 cp trc ngang

Bm ly tm 1cp trc ng


u im ca bm ly tm: - To c lu lng u n p ng yu cu k thut, th cung cp

u n khng to hnh sin. - S vng quay ln, c th truyn ng trc tip t ng c in. - Cu to n gin, gn, chim t din tch xy dng m khng cn kt

cu nn mng qu vng chc. Do gi thnh ch to, lp t, vn hnh thp.

- C th dng bm nhng cht lng bn v khe h gia cnh gung v thn bm tng i ln, khng c van l b phn d b h hng v tc do bn gy ra.

- C nng sut ln v p sut tng i nh nn ph hp vi phn ln cc qu trnh.

V vy, gn y bm ly tm dn dn thay th bm pittng trong trng hp p sut trung bnh v thp, cn nng sut trung bnh v ln.

Tuy nhin bm ly tm cng tn ti nhiu nhc im cn nghin cu ci tin:

- Hiu sut thp hn bm pittng t 10 n 15% - Kh nng t ht km nn trc khi bm phi mi y cht lng cho

bm v ng ht khi bm t cao hn b cha. Nu tng p sut th nng sut gim mnh so vi thit k do hiu sut

gim theo.

Bm a cp nm ngang


Bm a cp trc ng

1.2 Bm trc vt

Bm trc vt c s dng khi bm cc sn phm vi bn c p lc ln v trnh to tia la in.

Bm c th c mt, hai, hoc ba trc vt t v tr nm ngang hoc thng ng. Loi bm ba trc vt th trc gia l trc dn v hai trc bn l trc b dn. Khi lm vic bnh thng trc dn khng truyn momen xon cho cc trc b dn m cc trc ny xoay di p sut cht lng. Cc trc b dn ch c tc dng bt kn. 2. H thng van (valves)

Van c s dng thm trong h thng ngt chuyn hoc iu chnh

dng cht lng. Da vo chc nng ca van, s thay i trong trng thi dng ca van, c th iu chnh c bng tay, hoc t ng nh ci tn hiu t thit b iu khin, hoc l van c th t ng tc ng thay i ch ca h thng. Mt s loi van v nhng ng dng ca chng s c m t trong phn ny.


2.1 Van chn Van chn l loi van c dng ngn dng chy hoc mt phn dng

chy nhm t c mt dng chy mi sau van. Yu cu c bn thit k mt van chn l a ra tr lc dng ti thiu v tr hon ton m v t c c tnh dng kn v tr hon ton ng. Van cng, van cu, van bi, van bm, van mng c th p ng c tt c cc yu cu trn nhng mc khc nhau, v vy c s dng rng ri trong vic ng ct. Nhng kiu van thc t c nh gi bng cc thng s sau:

- Chnh p - kn - c tnh dng cht lng - Kn h thng - Yu cu tc ng - Chi ph ban u - Bo dng Van cng hay van ca (gate valve): Van ca c thit k lm vic nh

mt van chn. Khi lm vic, van loi ny thng l ng hon ton hoc l m hon ton. Khi m hon ton, cht lng hoc l kh chy qua van trn mt ng thng vi tr lc rt thp. Kt qu tn tht p lc qua van l ti thiu.

Van ca khng nn dng iu chnh hoc tit lu dng chy bi v khng th t c s iu khin chnh xc.

Hn na, vn tc dng chy cao v tr van m mt phn c th to nn s mi mn a v b mt trong van. a van khng m hon ton cng c th b rung ng.

Van ca bao gm ba b phn chnh: thn van, c van v khung van. Thn

van thng c gn vi ng ng bng mt bt, ng vt, hoc ni bng hn.


C van bao gm cc phn chuyn ng c ghp vo thn thng thng l bng bulng cho php bo dng v lau chi. Khung van bao gm ty van, ca van, a van v van hnh nhn. Hai loi van ca c bn l kiu van hnh nm v kiu van hai a. Ngoi ra cn c mt s kiu van ci tin t hai loi a trn.

Van cu (Globe valves): Van cu truyn thng dng chn dng chy.

Mc d van cu to nn tn tht p lc cao hn van thng (V d: van ca, x, bi) nhng n c th dng trong trng hp tn tht o lc khng phi l yu t iu khin.

Van cu bao gm: van cu kiu ch Y v van gc.

Van cu thng c s dng iu chnh lu lng. Di lu lng iu

chnh, tn tht p lc v ti trng lm vic phi c tnh ton n khi thit k van phng van sm b hng v m bo vn hnh thng sut.

Van cu thng l loi c ty ren trn tr van loi ln th c kt cu b ngoi bt bulng bng n gnh. Ph kin ca van cu cng ging nh ph kin van ca. Bo dng van cu th tng i d dng v a van v van cng pha. Vi a c nh, a thng c b mt phng p ngc vo van ging nh mt ci np. Kiu thit k van ny khng ph hp vi tit lu p sut cao v thay i.

Van cu l nhng van tn ti thng xuyn nht. Nhng kiu van khc cng c thn cu. Do , n da vo cu trc bn trong xc nh kiu van. Li vo v ra ca van c sp xp theo nhng yu cu ca dng chy.


Van cu truyn thng dng chn dng chy. Mc d van cu to nn tn tht p lc cao hn van thng nhng van cu c th c dng trong trng hp tn tht p lc khng phi l yu t iu khin na.

Van cu thng s dng iu chnh lu lng. Di lu lng iu chnh tn tht p lc v ti trng lm vic phi c tnh ton n khi thit k van phng van sm b hng v m bo vn hnh trong sut.

Van phi chu p sut cao v thay i trong lnh vc tit lu phi c thit k kiu van phi rt c bit, thng s dng hai loi van sau: Van cu c ln in hnh ghp bch v van cu gc vi mp bt bulng.

Cu to gm cc b phn chnh nh: tay vn, c van, ty van, vng chn a c, thn van, a van, van. Hot ng: a van truyn thng ngc vi kiu a cm, to ra lp tip

xc mng gia truyn thy hnh bp mng v b mt a. Din tch tip xc hp ny rt kh b ph v v vy lm kn p lc d dng. Kiu thit k ny cho php chn kn v tit lu hp ly trong van cu quay, a v hnh nhn thng c trng bng ng thau. Trong van cu bng thp dng n nhit vi 7500F, van thng c m thp khng r. Cc b mt thng c ti luyn nhit t c c gi tr cng khc nhau. Nhng loi vt liu khc, bao gm v hp kim Coban cng c s dng.

B mt van l nn, m bo chc chn ton b b mt c tip xc khi van ng. Vi nhng loi c p lc thp hn, mt phng tip xc c duy tr bi cc a kho vt di.

a quay mt cch t do quanh ty van trnh lm xc b mt a v hnh nhn. Ty van da vo mt tm chn cng, trnh lm xc ty van v a im tip xc. 2.2 Van iu chnh

Van iu chnh c s dng thm cho h thng ng ng iu chnh dng cht lng, ph thuc vo mc ch ban u l iu khin dng chy, p lc hay l nhit m nhim v t ra l tng hoc gim dng cht lng qua van nhm tho mn tn hiu t b iu chnh p sut, lu lng hoc nhit .

Yu cu u tin ca mt van iu chnh l iu chnh lu lng dng chy t v tr m n ng trong di p sut lm vic m khng b ph hu. Nhng


van thit k c bit nh l cu kim, bm, bi, mng c kh nng p ng nhng yu cu trn cc mc khc nhau. Cc nh sn xut nn chn la gii hn lm vic cho tng loi van c th.

Van nt: Van nt cn gi l van ly, thng c dng duy tr lu

lng y ging nh van ca ni cn phi tc ng nhanh. N thng c dng cho hi, nc, du, kh v cc p dng ho cht lng. Van ht thng khng c thit k iu chnh lu lng. Nh vy mt s loi van ny c thit k mt cch c bit dc dng cho mc ch ny, c bit l cho tit lu dng kh.

Thn v a hnh cn mang li nhng c tnh cn thit cho van ht. Thit k cn thn phn thn trong van c th mang li hiu sut dng chy rt cao. Ca ca a hnh cn thng l hnh ch nht. Tuy nhin, mt s loi van c th kt cu cng trn. Nhng kiu van ch yu l dng bnh thng, dng ng venturi ngn, ca trn v nhiu ca.

u im ca van nt ni chung c th c sa cha nhanh chng hoc l

ra sch m khng cn thit phi tho thn van ra khi h thng c ng. N c th c s dng trong lnh vc t p sut chn khng n 10.000 psi v


nhit t -50 n 1500F. Cc van nt c th c trng vi rt nhiu vt liu khc nhau, ph hp vi nhiu ng dng cho ho cht.

Van dng mng: Van dng mng c rt nhiu thun li trong nhng ng

dng vi p lc thp m khng th t c bng cc van khc. Dng cht lng chy qua van mt cch u n, gim thiu tn tht p lc.

Van ny rt ph hp vi nhng ng dng hin i vo lnh vc tit lu, n mang li c tnh lm kn tuyt vi.

Dng cht lng c ngn khi nhng phn lm vicca van ngn chn tp cht, ho cht lng v s mi mn cc kt cu c kh. Bi v khng c r r dc theo xung quanh ty van nn loi van ny hon ton kn. c tnh ny lm cho van tr nn quan trng trong cc ng dng, v n khng cho php c r r ra khi hoc t ngoi vo h thng.

Van mng bao gm thn van c van t dng chy, mng van mm do to nn mt vng p lc phi trn van, mt my nn kh dng to p lc ln mng ngc vi van, c van v tay vn bo v mng v thn van khi c tc ng t my nn.

p sut ti a m van mng chu c l kh nng chu p lc ca vt liu

lm mng v nhit lm vic. V vy, tui th thit k ca van cng b nh hng bi mi trng lm vic. Ngoi ra, p lc thu lc ca h thng khi kim tra phi ln hn p lc ti a m mng c th chu c.

Van mng dng ng thng dng trong cng nghip bia ru, n cho php s dng qu bng hnh cu chi van cng vi hi nc v dung dch kim m khng cn phi tho van ra khi ng ng.

Van bi: Van bi l van xoay vng, ng dng cho kh, kh nn, cht lng

v va xy dng. Vic s dng nhng vt liu lm kn, mm nh l nylon, cao su tng hp, polime to ra kh nng l kn tuyt vi t -450 n 5000F


Vn hnh van bi cng ging nh van ht, chng khng c mi ghp v to

ra kn t. Van bi to ra tr lc l tng cho dng chy do c ca v thn van rt trn tru v u n. Cho nn, van bi c s dng ng\m hon ton trong qu trnh xut nhp.

Nhng thnh phn chnh ca van bi l thn van, nt hnh cu v . Van bi c th c thit k 3 dng: ca van ng Venturi, ca trn, ca gim dn. Van ca trn c ng knh trong bng ng knh trong ca ng. Trong kiu van ca Venturi v ca gim dn, ca van thng b hn ng ng.

Van kim (Needle valves): Van kim thng c dng cho dng c o,

ng h, b ch bo v thit b o m. Van kim t c chnh xc cao v v vy n thng c dng trong cc ng dng c nhit cao v p lc cao.


Trong cu to van kim, im di ca ty van l u kim. Kim c khp mt cch chnh xc vo lng van, v v vy m bo hon ton kn v tc ng m ng nh nhng.

Van bm: Van bm l van thit k hiu qu dng p lc thp, thng

c dng iu khin v iu chnh lu lng. c trng ca van bm vn hnh nhanh v tn tht p lc thp. Van ch cn quay vng t v tr ng sang v tr m hon ton.

2.3 Van kim tra

Van kim tra thng c dng ngn dng chy ngc. l dng van c a van t tc ng, m cho dng chy v ng rt nhanh khi c dng chy ngc li. Cc ng dng c b tc ng bng kh nn c th c dng ng nhanh van khi c tc ng ngc. Cc loi van kim tra l: van kim tra kiu ch T, kiu ci u, van kim tra a rn, van ch Y; trong van kim tra kiu ci u thng c s dng nht. 2.4 H thng x p

Van an ton v van x p sut: Cc van an ton v van x p sut l cc thit b t ng x p sut s dng bo v qu p trong ng ng v thit b. Van bo v h thng bng cch x ra p lc d tha. p sut bnh thng, a van c ng vo van v c nh bi mt l xo b nn t trc khi p lc h thng tng ln, p lc to ra bi cht lng v a van tng gn bng p lc l xo. Khi m cc p lc trn cn bng, cht lng s chy ra qua ca van ra ngoi.

Cc van an ton thng dng cho kh v c tnh khi m v ng ca n thch hp vi c tnh v s nguy him khi b nn ca cht kh.

Van x p thng dng cho cht lng. Chc nng ca cc van ny ging

nh van x p an ton. Ch khc cht lng khng gin n, nn khng c lc ny


pht sinh thm tc ng vo a, v vy lc ny van gim bng p lc h thng. Van s ng khi p lc thp di p lc t sn.

a ph hu: Mt dng thit b x p c bit l a ph hu. Thit k

thng l cc mt bch vi cc l dp su bng my bn kn h thng ngn chn n trt gia cc a.

a c thit k b ph v mt p lc nh sn. Nhng thit b my c nhng u im c bit khi ta phi x mt lu lng ln kh hoc cht lng ra ngoi.

a ph hu cng c th c dng vi van an ton dng l xo. Bng cch s dng a ph hu x p sut p sut vo khong 5-10% ln hn p lc t ca van an ton, a ph hu s tc ng nu van an ton x p khng hot ng tt. Cng vy ni m khng chp nhn vic r r, a ph hu cng c th c lp t gia van v b phn cn c bo v.

Khi vt qu p sut thit k ca a ph hu, n s n v van x p s m ra khi p sut vt qu p sut t.

Van ca hoc van x c th c lp trc a ph hu. Khi lp a ph hu, nhng van ny c m m bo rng h thng c bo v. Vic ng cc van ny li cn thit ct dng chy khi bo dng hoc thay a sau khi thc hin chc nng ph hu.

p lc thit k ca a ph hu khng th iu chnh c. Cc thit b bm v van thng phi tha mn cc uu cu nh: - Hot ng n nh - D iu khin - Hn ch ti a s c trong qu trnh iu hnh (n mn,.) - Phng chy cha chy (hng u) dng bm ly tm (bm trc vt

d pht sinh tia la in) - Hn ch t van trn ng ng y (ng ng ra) - Bm pittng khng c s dng do khng n nh v d pht sinh tia

la in. 3. Dng c o


Trong cc b cha du th v cc sn phm du m, ngi ta thng s dng cc dng c o xc nh:

- Cc thng s ho l ca sn phm nh nhit , p sut, . - Cc thng s ni ln tnh an ton ca sn phm trong tn tr nh bay

hi, p sut hi bo ho trn b mt, nhit ca sn phm, - Cc thng s lin quan n vn vn chuyn nh l lng, khi lng,

mc cht lng, - Tt c cc thng s trn c nhiu hnh thc hin th khc nhau tu theo

loi dng c s dng: thang chia vch (scale), dng s (digital), lu (recorder) hay trn mn hnh my tnh (monotor).

- Cc tnh cht bt bin nh: chnh xc, n nh, - Cc tnh cht ng nh: nhy, tin cy,

3.1 Thit b o nhit

Chng ta cng bit rng qu trnh truyn nhit xy ra 3 hnh thc ch yu l i lu, dn nhit v bc x. Da trn nhng nguyn tc truyn nhit trn m ngi ta ch to cc thit b o nhit khc nhau.

Cc dng c o trong cng nghip ni chung: nhit k thu ngn, nhit k lng kim, nhit k p sut l xo, cp nhit in, nhit k in tr, nhit k o nhit cao. Trong h thng bn b ca cng nghip du kh, ngi ta thng s dng cc loi nhit k sau:

- Nhit k lng kim ( bimetallic thermometer) - Nhit k p sut l xo ( pressure spring thermometer) - Cp nhit in (thermocouple) - Nhit k in tr ( resistance thermometer) Nhit k lng kim C ch hot ng ca loi nhit k lng kim da trn nguyn tc hai kim

loi khc nhau s c gin n nhit khc nhau.

Mt s nguyn t lng kim c to ra bng cch nung chy cho hai

thanh kim loi dnh li vi nhau sau to thnh mt thanh hnh xon c. Di tc dng ca nhit , hai thanh kim loa gin n nhit khc nhau v lm cho thanh xon c co gin. Chuyn ng ca thanh xon c ny tc ng ln kim ch th trn mt ng h thng qua mt thanh kim loi khc. Tm li, nguyn tc hot ng ca loi nhit k lng kim l:

nhit nguyn t lng kim co gin kim ng h quay


Nhit k lng kim dng xc nh nhit trong khong -1500C n

4200C. nhit cao hn na th kim loi c xu hng gin n qu lm cho php o khng cn chnh xc na. Loi nhit k ny rt ph bin trong cc bn b cha sn phm du m.

Nhit k p sut l xo: u im ca nhit k ny so vi nhit k lng kim l v tr c nhit c

th xa bn m khng cn c ti ch nh khi dng nhit k lng kim. Khi ngi k s c th trong phng hay mt v tr thun tin kim tra nhit ca bn.

Cu to chnh ca loi ny l mt ng xon rut g (ng Bourdon) c ni

vi kim ch vch. ng ny c ni vi mt bu cha cht lng ( thng l thu ngn) hay hn hp lng kh ( thng l Nit). Di tc dng ca nhit th p sut trong bu tng ln do cht lng gin n hay p sut hi bo ho tng ln. S tng p sut ny tc ng ln ng xon rut g lm cho n gin ra lm chuyn ng kim ch vch. Tm li nguyn tc hot ng ca loi nhit k ny l:

nhit p sut ng rut g co gin kim ng h quay gi tr nhit

Cp nhit in: u im ln nht ca cp nhit l chuyn tn hiu nhit sang tin hiu

in, t cc k s c th d dng x l tn hiu ny trong dy chuyn t ng ho v d nh dng tn hiu in ny iu khin cc thit b khc. Hn na gi tr nhit o c s v cng chnh xc v tn hiu in c th chuyn sang tn hiu s quan st trn mn hnh ( khng ph thuc tnh ch quan ca ngi quan st).


Cp nhit in bao gm hai kim loi khc nhau ni vi nahu hai u. u tip xc vi mi trng cn o nhit c ni dnh vi nhau, u cn li c ni vi milivn k. Nh vy cp nhit in s c mt u c nhit thay i: u d v mt u c nhit c nh: in cc tham kho. Khi nhit u d khng i th hiu in th hai u in cc tham kho cng khng i. Khi nhit u d tng th hiu in th in cc tham kho cng tng. Tn hiu in ghi nhn c chnh l s tng hiu in th. Trong milivn k c mt nam chm vnh cu rt nhy vi s thay i ca hiu in th. Nam chm ny lm quay cun dy ni vi kim ng h c thang chia nhit sn. V vy, milivn k ni vi cp nhit in khng phi o trc tip nhit m o s thay i hiu in th. Chnh v vy hiu in th thay i theo nhit nn chng ta mi c th xc nh c nhit thng qua milivn k.

C ch trn c th tm gn nh sau: nhit hiu in th milivn k nhit c Nhit k in tr: Nhit k in tr cng c nguyn tc hot ng gn ging vi cp nhit

in. S thay i hiu in th cng c dng xc nh s thay i nhit . u d ca nhit k l mt in tr gm dy ng, niken hay platin qun quanh mt vt cch in nh mica chng hn. in tr u d c mc vi 3 in tr khc to thnh cu Wheatstone. Dng in qua in tr cp bi pin. Khi nhit mi trng tng th in tr tng lm thay i hiu in th hai u cu Wheatstone. S thay i hiu in th ny c ghi nhn bi milivn k tng t nh trong cp nhit in.

Qu trnh trn c th tm tt nh sau: nhit in tr hiu in th milivn k nhit c

3.2 Thit b o p sut

p sut trong bn dung kim tra an ton ca bn khi cha cc sn

phm kh ho lng. Trong mt s trng hp p sut cn xc nh lng kh ho lng trong bn. Mc d cc bn u c van x p nhng vic theo di p


sut bn cng gp phn m bo cng tc vn hnh v bo tr, pht hin r r t bn cha

Cc thit b o p thng c s dng l: ng Bourdon: ng Bourdon l nhn t nhn bit

p lc chung nht. y l mt ng kim loai dt bng phng, c bt kn u cui cng v c un cong thng ch C hay hnh xon c, khi bn trong hay bn ngoi b mt ca ng c nhng khu vc khc nhau. S khng cn bng lc gy ra bi p lc s lm cho ng b bung ra. S thay i ny c th c trc tip trn dng c o hay chuyn thnh mt tn hiu in hay kh nn tng xng vi p lc. Cn phi bo dng trnh s n mn v ng cn bn trong ng v c th nh hng ti c tnh ca n. Trong bn b kn v bn b cha kh ho lng thng dng loi p k ng xon Bourdon.

Mng ngn (mng chn): Mng chn c s dng rng ri nh mt thit b c chnh xc cao. N

bng phng hoc c np gp da trn loi p lc c iu chnh bng tay v thch hp trong vic o p lc mt vi mmH2O hng ngn psi. Mng chn c thit k truyn lc hay gii hn s vn ng. Chng tt hn ng Bourdon bi v c ch to t kim loi chng n mn hay c ph mt lp n hi nh Teflon. 3.3 Thit b o mc cht lng

Vi bn cha sn phm du m dng lng th ngi ta quan tm n mc cht lng. Khi xut th khng xut ht ( tr trng hp v sinh bn) v khi nhp th khng nhp y. m bo iu ny ngi vn hnh cn phi bit cht lng dng n mc no trong bn. Cc dng c o mc cht lng kh a dng, v d nh dng o trc tip:

- Phao ni (float) - Phao chim ch (displacer) - u tip xc trc tip (contact) - u d in (electric probe) - Ngoi ra cn c cc loi dng c o mc cht lng gin tip nh: - Dng c o dng p sut thu tnh (hydrostatic pressure) - Dng c o dng bc x (radioactive device) - Dng c o s thay i khi lng (loss of weight device) Phao ni:


Phao ni l loi dng c kim sot mc cht lng thng dng nht. Phao ni n gin nht l loi phao ni mt v tr (single point float). Loi ny gm c mt phao bng nha ni vi mt cnh tay n. Cnh tay n ny iu khin van cp liu cho bn trng thi ng hay m. Ban u khi mc cht lng di mc cn thit th van trng thi m. Khi mc cht lng v tr mong mun, phao ni ngang vi mc cht lng cn bm, tc ng ln van thng qua cnh tay n lm ng van li. Phao ni c th gn bn trong bn hay gn trong mt bnh bn ngoi thng vi bn. Mt s loi phao ni khng dng cnh tay n m dng kh nn iu chnh van cp liu cho bn. iu ny c li ch tng nhy cho van nhng cng chi ph thit b ng k (my nn, ng ng dn kh).

Loi phao ni di ng hnh bnh rn (doughnut shape) cho php ngi vn hnh theo di mc cht lng dng kn trong bn. Phao ni ny di chuyn dc theo mt ng nhng chm trong bn. Phao ny l mt nam chm. Mt nam chm khc t trong ng s dng theo khi phao dng nh lc t gia hai thanh nam chm. Kim trn thang chia vch c ni vi nam chm trong ng bng dy cp. Nh vy chuyn ng ca nam chm lm kim di chuyn v t c c gi tr mc cht lng.

Phao chim ch: Nguyn tc hot ng ca loi ny da trn lc y Acsimet. V d mt cn

khi cha nhng vo cht lng s c trng lng 3kg. Nh vy lc tc dng ln cn ch c trng lc ng vi 3kg. Khi chm trong cht lng cao khong 1m th phao cn chu thm lc y Acsimet ngc chiu vi trng lc. Khi lc tc dng ln cn gim i v cn ch gi tr 2kg. Cht lng dng cng cao th lc Acsimet cng mnh v gi tr khi lng ca phao trn cn cng gim. Bng cch quan st khi lng, ngi vn hnh bn c th bit cht lng dng n mc no.

Thc t, ngi ta thng ni phao vi mt h thng kh nn. S thay i lc tc dng ln van kh lm thay i p sut kh. Quan st s thay i p sut kh cho php thay i mc cht lng d l rt nh. V th nhy ca loi dng c ny kh cao. Vi cc bn c chiu cao ln th ngi ta dng nhiu phao ni tip nhau cc v tr nht nh. Cht lng dng n phao no th lc tc dng ln ton b chui phao thay i n . Lc ny kch hot cc thit b kh nn nh ni trn v gip ta ghi nhn c mc cht lng trong bn.

u tip xc trc tip: Phng php tip xc ch yu c dng cho bn cha cc ht rn, tuy

nhin c th dng cho bn cht lng. V mt nguyn tc th khng c g khc bit khi thay i loi vt cht cha trong bn.

Vi ht rn th u tip xc l mt qu nng cn vi cht lng l mt ci phao. y, chng ta xt cho bn b cha cht lng nn u tip xc l phao. u tip xc c ni vi u cm bin nh mt thanh kim loi. Nu ban u cht lng ngp phao th lc Acsimet s tc dng ln phao v cm bin s ghi nhn c lc ny. Cm bin s truyn tn hiu iu khin motor quay ko phao ln. Khi cm bin ghi nhn c gi tr lc ng vi gi tr s th hin qung


ng i ca phao. Hay ni cch khc l mc cht lng dng ln trong bn. Khi phao ni th cm bin li iu khin bm cp liu vo bn cho n khi cht lng ngp phao v qu trnh trn li tip tc din ra theo chu k.

u im ln nht ca loi dng c ny l c th t ng ho hon ton vi chnh xc cao. Ngi k s c th lp trnh cho h thng vn hnh vi nhiu yu cu khc nhau v mc cht lng. D nhin chi ph cho h thng dng c ny kh cao do s dng cc cm bin t tin.

u d in: u d dn in, in dung, sng siu m l cc loi u d in ph

bin dng o mc cht lng trong bn. Hu ht cc loi u d ny dng kim sot mc cht lng mt v tr xc nh trc. Sau y chng ta xt nguyn tc hot ng ca 3 loi u d trn:

- Vi cht lng dn in th u d l mt cc cn thnh bn l mt cc. Khi cht lng ngp u d th c dng in gia u d v bn. Mi trng truyn in chnh l cht lng. Dng in c ghi nhn nh cm bin cho bit cht lng dng n mc quy nh hay cha. B tr y d nhiu v tr khc nhau s cho bit mc cht lng nhiu v tr khc nhau. C th gn thm cc n bo mc cht lng hay chung reo gip cho qu trnh vn hnh d dng hn.

- u d in dung c s dng vi nguyn tc gn ging vi u d dn in. Tuy nhin cht lng y phi khng dn in hay ni cch khc l phi c tnh in mi kh tt. Loi cht lng ny c th gp cc sn phm du m tinh khit nh nhin liu phn lc chng hn. Mt u d in dung gm cc bn cc nh trong mt t in. Khi mc cht lng dng ngp t th in dung ca t s c mt gi tr nht nh. Khi mc cht lng h xung th mt phn cc bn t s h ra. Khi cht in mi l hi bo ho ca cht lng. Nh vy in dung ca t s thay i bao hiu cht lng qua mc xc nh trn thnh bn.

- u d sng siu m v c bn bao gm mt u pht v mt u thu gn lin vi np bn. Gia u pht v u thu c mt ch h. u pht v u thu u lm bng vt liu c cu trc l nhng tinh th p in (piezo electric crystal). u d sng siu m c ni vi b iu khin bng cp in. B iu khin trung tm ny s pht tn hiu in n u pht. Sau u pht b kch thch v to ra sng siu m. Tuy nhin ch khi no cht lng ngp y ch h th sng siu m mi truyn c n u nhn. Ti u nhn, tn hiu sng siu m li c chuyn sang tn hiu in. Tn hiu in ny c khuch i bng cc b phn trong b iu khin trung tm v kch hot mt rle in. Rle in ny c th dng iu khin bm, van, trong khi nhp hay xut liu.

Loi u d ny tuy c gi thnh cao nhng li c bit hiu qu i vi cht lng c nht rt cao, cc loi cht lng c qunh hay c nht thp. Nguyn nhn l vi cht lng c nht cao s d bm dnh ln cc phao gy ra sai lch cho cc loi cm bin phao.


Khi dng u d sng siu m xc nh mc cht lng ti mt v tr xc nh th ngi ta s t u d ti mc thp v mt mc cao trong bn. Nu mun xc nh lin tc s dng ln ca cht lng th u d s c t np bn. ng vi mi mc cht lng khc nhau th khong thi gian t lc u pht truyn tn hiu sng siu m cho n khi u thu nhn tn hiu phn hi s khc nhau. Ghi nhn li thi gian ny th chng ta bit c cht lng dng n u. Nh vy nguyn tc ny cng ging nh cch ngi ta o su y bin.

Dng c o dng p sut thu tnh: Dng c xc nh mc cht lng da trn p sut thu tnh n gin nht l

ng h o p gn pha di y bn. Bt k mt s thay i mc cht lng no cng lm thay i p sut thu tnh v lm thay i gi tr ca ng h o p. Bng cch chia thang o ng h theo n v chiu di s gip xc nh mc cht lng trong bn.

Vi cc sn phm du m c tnh n mn ln hay phi tn tr nhit cao th khng th cho cht lng tip xc trc tip vi ng h. Khi ngi ta s dng khng kh truyn tc ng ca lc thu tnh ln ng rut g gn trong ng h. C th dng cc lu cht khc nhng tt nht l khng dng khng kh v gi thnh r v lun c sn. Sau y l mt s dng c c ng h o khng tip xc trc tip vi cht lng cha trong bn:

- By hi l mt hp nh c nhng chm su trong bn. Khi mc cht lng trong bn dng ln th p sut khng kh trong by s tng ln. Khng kh thng vi p k qua mt ng kim loi. Quan st p k hay chuyn thang o p sang thang o chiu di s xc nh c chiu cao mc cht lng.

- Mng ngn cng c nguyn tc hot ng tng t by hi. im khc nhau ch khng kh c gi trong hp nh mng ngn che y hp. Mng ny rt linh ng v c co gin cao. Khi mc cht lng trong bn tng th p sut thu tnh tc ng ln mng ngn. Sau mng ngn tc ng ln khng kh trong h kn lm gin ng Bourdon trong ng h. Quan st thang chia c th bit c mc cht lng.

- Phng php bong bng kh khng c s dng trong bn b cha sn phm du kh do to bt, kh quan st v cng khng chnh xc.

- Cc phng php gin tip trn ch c dng khi bn h, thng vi kh tri. Vi bn cha cc sn phm kh ho lng th mt phng php gin tip c th s dng l p k o chnh lch p sut. l mt ng ch U c cha thu ngn. Mt u ng thng vi y bn cha cht lng, u cn li thng vi khong khng gian cha hi bo ho trn bn. p sut thu tnh do cht lng gy ra mc thu ngn trong nhnh thng vi cht lng xung v lm mc thu ngn bn u cn li dng ln. Chnh lch mc thu ngn cho ta bit chiu cao cht lng trong bn cha.

Dng c o dng bc x: Loi dng c ny c th dng xc nh mc cht lng ti mt im hay

theo di mc cht lng dng ln mt cch lin tc.


Phng php bc x c dng khi sn phm c tnh n mn cao (phn on du th c hm lng H2S ln), hay nhit tn tr cao (bitum). Mt s trng hp khng th b tr cc loi dng c o khc th c th dng cc cm bin bc x.

Vi loi dng c o dng bc x, ngi ta b tr mt bn bn l cc u pht ra bc x, mt bn l u nhn tia bc x. Mc cht lng dng ln che cc u pht ra tia bc x. Cng bc x nhn c s gim dn. Tng ng vi s thay i cng bc x ca u nhn s quy ra chiu cao mc cht lng.

Dng c o s thay i khi lng: Loi dng c ny c bn l dng cm bin khi lng (load cell) ghi

nhn lng cht lng c trong bn. Trong cng nghip du kh, bn b rt ln v nn mng cng c nhng yu cu k thut nht nh. V vy s rt kh khn trong vic b tr cc load cell. Ngoi ra khi cc cm bin ny b h th vic ly ln thay ci mi khng phi d. Do ngi ta rt hn ch vic dng cc load cell.

Tuy nhin loi dng c ny cng c nhng u th nht nh. Do c th ca sn phm du kh l d bay hi v tu theo nhit mi trng m th tch lng cht lng c th khc nhau. V vy trong bun bn, tn tr v nh gi sn phm ngi ta u da trn khi lng. Khi s dng li dng c o mc cht lng thng qua o khi lng s rt c li. Bn cnh vic kim sot c mc cht lng, chng ta cn bit khi lng xut nhp l bao nhiu 3.4 Cc thit b h tr khc

Cc thit b ny gip kim tra bn, cc thng s k thut ca bn. Cc th nghim ny u theo tiu chun API. Cc thit b o chiu cao ca bn, ln ca nn, kim sot chu vi cng nh mo ca bn, b dy ca bn qua qu trnh tn tr, h thng ng ng ni vo bn. Ngoi ra cn c cc thit b o t trng, o nhit u, thit b o hm lng cn trong bn (theo API v ASTM).

Song song cn thit k thm cu thang xon gip kim tra cc b phn trn nh bn nh np bn, h thng lm mt

Ca ngi (hole man): Mi bn cha c 1-2 ca ngi lp t trn thnh bn, c ch to cng

loi vt liu vi thn bn. Ca ngi c thit k thun li thao tc v sinh, sa cha bn cng nh quan st mc cht lng trong bn.

chn la: Thng lm bng t hoc b tng, c b dy v chiu cao ln cha

ht cht lng c trong bn nu c s c Trong trng hp xy ra s c (v bn, chy, ) bc tng ny s ngn

cht lng li n khi n c bm sang bn khc hoc c bin php x l ng


thi n cn bo v, cch ly cc bn cha v cc cng trnh c s k cn trong trng hp xy ra s c, c lp m chy trnh ly sang cc khu vc khc.

H thng lm mt: Trong qu trnh tn tr, trong nhng iu kin nhit mi trng cao qu

nhit gii hn cho php lm cho nhit ca bn cng nh ca sn phm tn tr tng. y l nguyn nhn lm gim bn ca vt liu ch to bn cng nh vic gy tht thot v chy n nht l i vi nhng sn phm. Do ta cn phi lm mt bn bng h thng ng nc un cong theo thn bn pha tn np, dc theo ng ta khoan nhiu l trn cch u nhau cho nc c th lm mt ton b bn cha.

H thng chng tnh in: Do cc sn phm du kh trong qu trnh tn tr s xut hin cc phn t

tch in, khi s tch in ny ln s gy ra hin tng phng in gy ra s chy n rt nguy him. trnh hin tng phng in trong qu trnh tn tr ta cn phi dng bin php ni t thit b bng nhng cc tip t.

Thit b pht hin r r: Trong qu trnh thi cng cc bn c kim tra v kh nng r r v nu

t yu cu th mi i vo hot ng. Tuy nhin trong qu trnh vn hnh c th pht sinh cc vt nt, l rn do va chm c hc hay do tc ng n mn ca lu cht cha trong bn. Khi lu cht c th r r ra ngoi gy tht thot sn phm, nhim mi trng, d gy chy n, gim bn c ca bn. Vi cc s c r r ln ca cht lng hay cht kh th c th pht hin d dng bng cch quan st thng xuyn hay bng ng h o p. Vi cc v r r rt nh kh pht hin, lu ngy s nguy him th ngi ta tin hnh kim tra nh k bng cc thit b chuyn dng.

H thng phng chy cha chy: Lp t cc ct thu li trong khu vc bn cha phng st, cc ct thu li

ny phi cao v b tr iu trong khu vc. S dng cc thit b chuyn dng trong thao tc trnh tch in gy chy n.

Lp t h thng vi tc trn cc bn, m bo nc ti cho cc bn. Trn h thng ng ny cy thm h thng ng dn bt cha chy. Nu c xy ra s c th bt cha chy s theo nc phun vo m chy c lp m chy ngn khng cho tip xc vi khng kh v dp tt m chy.

Lp t cc ct nc cha chy nhng v tr thch hp sao cho c th cng lc cha chy cho hai khu vc khc nhau. Ngun nc phi m bo cung cp cho nhu cu. Cn phi duy tr p lc cho cc vi phun nc cha la m bo an ton cho nhn vin cha chy.

Trn thnh chn la( firewall) b tr cc vi phun bt cha chy khi cn thit. Cc h thng phun nc v bt cha chy c th hot ng t ng khi c s c hoc bn t ng.


Lp t h thng vi nc trn mi bn cha d ti nc cho ton b vng cha bng 5 vi phung vi tc 0,04 lmp gal/min/ft2 b mt bn. Cc vi nc my phi c lp t ti nhng v tr thch hp sau cho n c th cung cp nc cha chy cho t nht hai v tr khi c s c.

Ngun nc phi cung cp t nht trong 4 gi (k c lng nc dng ti cho bn). p sut ca vi cha chy phi ln hn hoc bng 8kg/cm2.

Phi t nht mt h thng ti nc di ng, dng ti bo v cho ngi ng cc van gn ni ang chy. Van gim p lp t trn mi bn phi c ni trc tip vo phn hi bn trong bn bng ng thng hi thng ng cao t nht 2m.

Phi c thm cc bnh cha chy bng ha hc thch hp. V tr t cc bnh ny phi gn nhng ni d xy chy n. Vi kho tn tr c 100m2 phi c mt bnh cha chy. Vi nhng h thng phn phi phi c mt hoc hai bnh ti bn cha


Phn 2

K THUT NG NG


Chng 5

THIT K H THNG NG NG 1. Tng quan

Mc tiu chnh ca thit k l thu thp s liu, hnh thnh cc tng chnh, la chn phng php thch hp, cung cp c s thng tin thc hin thit k chi tit.

Cc qu trnh thit k cho cc ng ng t lin v ngoi bin tng t nhau v phng php tip cn vi phng din, v d nh la chn vt liu, thit k thu lc nhng li hon ton khc nhau cc kha cnh khc, v d nh la chn tuyn ng, la chn dy ng

ng ng ngoi bin v trn t lin c cng mc tiu v mt an ton, tho mn mc ch ca h thng ng ng. Tuy nhin, v mt dch v v loi cp liu th chng hon ton khc nhau, ngoi ra cc iu kin mi trng, nguyn nhn h hng, phng php thi cng lp t cng khc nhau.

Cc giai on trong qu trnh thit k khi nim thng c nh hng ln nhau, do qu trnh thit k h thng ng ng lun l qu trnh lp. Hiu qu ca qu trnh thit k khi nim ph thuc ch yu vo chnh xc ca cc s liu ban u.

Cc d n ng ng c thit k theo ba giai on: 1.1 Thit k s b ban u

C th dng phng php Broad brush xem xt tt c cc kh nng c th nh gi d n v mt kinh t. Nn tip cn vn mt cch d dt, va phi. Trong giai on ny khng cn thit tin hnh cc nghin cu su tr khi nh gi c rng d n c gi tr v nhy cm ca n thay i. 1.2 Thit k khi nim

T k hoch c ngh trong thit k s b, trong giai on thit k khi nim ngi ta thc hin nhng thit k c nh gi l c li hn. giai on ny phi thc hin nhng nghin cu su nh gi phng php thit k ti u dng trong giai on thit k chi tit. Thit k khi nim nn chn ra k hoch thch hp thc hin tip tc d n trong giai on thit k c s (chi tit). 1.3 Thit k c s

Trong giai on thit k c s, nh ngha cui cng ca ng ng c quyt nh. Qu trnh ti u ho k hoch thch hp c thc hin trong giai on thit k khi nim. Giai on thit k c s gm vic xem xt cc k hoch khc nhau trong s cc k hoch c tnh kh thi c a ra t giai on thit k s b. Mi phng n thit k c xem xt v nh gi qua qu trnh thit k so snh cc kh nng v la chn thit k kh d nht cho giai on thit chi


tit. Ngoi nhng tnh ton ti u ho thit k, giai on thit k c s c thc hin nhm:

- La chn thit k ti u v cc qui lut vn hnh tip tc pht trin d n.

- Hng dn qu trnh thu nhp d liu hon thin cht lng ca cng ngh mt cch chi tit.

- Tin hnh cc nghin cu thc hin cc phng php cng ngh mi c ngh a vo trong d n.

- Hng dn cc cng vic lp lch trnh v chi ph thc t cho giai on thc hin d n.

- Chun b cc tiu chun k thut thc hin thit k chi tit. - Bt u tin hnh cc giao dch v t vn vi i tc th ba ca d n. - Ngoi ra, cc mc trch nhim i vi cc giai on khc nhau phi

c lm r mt cch c th. Trch nhim i vi giai on thit k s b l phi xc lp c tnh kh thi v mt kinh t.

- Trch nhim ca giai on thit k khi nim phc tp hn v lin qua n tnh kh thi v mt k thut, ti u ho v mt k thut v kinh t tng th. Trong giai on thit k chi tit trch nhim l an ton v mt kinh t

2. Thit k khi nim cho ng ng

Do tnh cht lp ca qa trnh thit k khi nim, nhiu mc trong qu trnh thit k c thc hin ng thi. 2.1 Thit lp chun thit k

Ngi thit k phi lp dng ca c s d liu cho thit k, cc tiu chun cho thit c chp nhn trong sut qu trnh thit k khi nim. C s d liu nn bao gm cc thng tin lin quan n:

- Cc yu cu v lut hoc yu cu ca quc gia bt k no khc. - Cc iu lut (regulations), qui tc (code), v cc tiu chun (standard). - Cc yu cu vn hnh. - D liu v sn phm, d liu v qui trnh v cc thng tin cng loi . - D liu mi trng (tuyn ng trn t lin): tc v hng gi c kh

phn tn cht (thit b t l), cc mc v lu lng ma, su mc nc h thng bo v n mn ngm, bin thin nhit

- D liu mi trng (tuyn ng ngoi bin): cc c tnh v mnh, hng v chu k ca gi, sng, dng chy.

- Cc chi tit kho st v tuyn ng. - D liu t/y bin dc theo tuyn ng d kin. - Cc yu cu ca pha th ba ti ch ct nhau, a im cc di tch lch s

hoc c tnh quan trong v mt mi trng, trung tm dn c - Hng pht trin khu vc, ly t k hoch pht trin d n. - D kin v gin/trm.


Ti liu ny nn c ph duyt bi ngi qun l d n v phi cp nht thng xuyn v lin tc khi c thay i. Vai tr ca ti liu ny rt quan trng v n hnh thnh nn tng cho qu trnh thit k. giai on thit k khi nim khng cn thit phi bo mt nhng d liu dng cho thit k chi tit, tuy rng bo mt mt vi loi thng tin c th hu ch. 2.2 La chn tuyn ng

Cc yu t nh hng n vic la chn tuyn ng c th xem xt theo hai lnh vc tng qut sau:

- Yu cu ca bn thn h thng s dng ng ng. - nh hng t bn ngoi bi pha th ba. Tuy rng vic tp trung vo cc yu cu ca qu trnh l quan trng, nhng

cng khng nn xem nh nh hng ca cc yu t bn ngoi. S quan trng ca vic s dng t vn v xem nh pha th ba khng th

nhn mnh thi qu. Vic thiu quan tm n cc vn ca pha th ba c th dn n vic phi thit k li c k hoch. V d, vi ng ng t lin, v tr ca trm my nn chin lt khng th thi cng c chng hn, khi ton b d n tr nn khng kh thi v mt kinh t.

Thit k khi nim nn gii quyt tng quan ca tt c cc phng din x hi, chnh tr, mi trng v pha th ba bng cch kho st h tr ton b tt c cc tuyn c th. Cc kho st bao gm nghin cu gn nhau i vi tuyn ng t lin.

ngha ca nghin cu gn nhau trong thit k khi nim ca ng ng t lin l ch ra cc v tr m ng ng c th gy ra nguy hi cho i sng c dn hoc ng thc vt ni bn a. cc v tr nh vy cn lu nhiu hn n vic gim ri ro cng nh nh hng ca bt k s c no n ng ng.

Giai on thit k khi nim ny thng c thc hin trong qu trnh xc nh ca d n v nn loi b tt c cc tuyn ng khng nghim tc m khng c xem xt y .

Mt cch in hnh, thit k khi nim nn bao gm: - Thit lp cc hnh lang tuyn ng c th. - Thit lp cc phng php xy lp cho mi hnh lang. - Thit lp cc vn nh hng ca mi trng x hi, chnh tr, pha th

ba mt cch y . - nh gi v mt k thut ca hnh lang. - Thit lp hnh lang tt nht trong cc hnh lang xem xt. S xem xt thi qu tm quan trng ca nh hng t cc vn x hi,

chnh tr, mi trng, pha th ba trong giai on ny c th to ra nh hng nghim trng n vic thc hin d n. iu quan trng l vn ny c gii quyt mt cch tng th v tt c cc vn phi c c s chp thun v cho php. Thc hin cng vic ny cn phi thn trng v nn thc hin sao cho khng gy ra qu nhiu s quan tm ca cng ng dn c i vi nhng tuyn ng khng thch hp, iu ny c th gy hi cho d n v mt chnh tr.


La chn tuyn ng t lin khc nhau ng k so vi ng ng ngoi khi nhng nhn chung chng cng tng t nhau mt s c im k trn. S khc nhau c th ca chng c bn lun phn tip theo.

ng ng t lin Chn tuyn ng t lin l mt qu trnh lp da trn s xc lp mt cch

tun t rng buc. Nhng ch dn ca chnh quyn i phng, qui tc v tiu chun l yu cu ti thiu, ngoi tr cc iu khon lin quan n vn an ton cho cng ng i vi tuyn ng dn kh. Cc qu trnh nh gi mi trng lm li cho qu trnh la chn tuyn ng bng cch xc nh r t u c nh hng nh vy. Cc so snh v chi ph khi chuyn hng tuyn ng trnh cc khu vc rng buc c th tr gip cho qu trnh thit k nhng iu ny ch c gi tr khi s lin h tng th ca c tuyn ng v mi trng dc theo tng tuyn ng c so snh trn c s tng ng nhau. Vic cho php ch t tc ng n vic la chn sp xp chi tit v vic la chn li tuyn ng chnh trnh nhng ngi phn i ch c tnh kh thi khi m din tch t c lin quan l ti thiu.

ng ng ngoi khi Tuyn ng an ton ngn nht c la chn ph hp vi a hnh y bin

v cc yu cu trnh cc khu vc y bin khng n nh, nhng im khng c thng tin r rng, ch m tu, lu cc vng hn ch th neo, ng trng nh c, bin gii quc gia v vng, cc k hoch pht trin trong tng lai.

Cc vn lin quan n vic lp t cc ng ng gn vi gin, ging khoan di y bin, cc ng ng c sn th cn c quan tm c bit v nh hng khng nhng n cc tuyn ng mi m cn nh hng n s la chn phng php thi cng lp t. su c th cng l mt rng buc quan trng v i hi phi pht trin gii php k thut mi khi lp t ng ng, lp thm ng nhnh hay sa cha .

Vic la chn v tr tip b v ct b bin i hi phi c kho st ton din v b nh hng bi v tr ca trm v cc thit b x l. iu ny c th d b nh hng bi mi trng do vy cn phi c nh gi ngay t giai on u. Ti ni tip b ng ng s chu nh hng phc tp ca dng chy y bin kt hp vi thy triu, sng khc x, sng v v cc dng chy ven b. c im vt l nh b mt vch , n ct c th phi c xem xt v mi gii php c xut c tnh kh thc hin hoc mi cn phi c nh gi. 2.3 Trm bm v chi ph

Thit k khi nim ng ng i hi s cn bng ca cc yu cu mu thun nhau v mt kinh t. Trong trng hp c bit, s tng tc gia nng sut, ng knh, p sut, thit k bm v khong cch bm cn phi c xem xt cn thn. iu ny phc tp hn khi xem xt chi ph tng theo hai loi chi ph: chi ph u t v chi ph vn hnh.


Cc phng php tnh ton doanh thu ha vn (thng t l vi nng sut) cn phi c tham kho thm cc ti liu khc. Tuy nhin mc nh hng ca chi ph n thit k cn phi c lm r.

Chi ph u t bao gm chi ph sn xut ng, ph ng, vn chuyn ng, o rnh (trn t lin), t ng, lm rnh (ngoi khi), cc chi ph ny tng khi ng knh tng.

Khi p sut m thp hoc ng ng di c th cn n h thng bm. Khi chi ph u t bao gm bm, ng c, nh xng, ng giao thng, gin (ngoi khi) v cc thit b ph tr khc. C th thy rng, cng t trm bm hoc bm c cng sut cng nh thi ng knh ng tng ng phi cng ln, hoc ngc li, chi ph loi ny s tng khi ng knh ng gim.

Chi ph vn hnh bao gm kim tra tuyn ng (thay i t nhiu tu theo kch thc ng), bo tr bm, chi ph nhn cng vn hnh v nhin liu. Cc yu t khc cng cn c xem xt bao gm chi ph dng h thng v bo tr. Nng sut ng ng nn c xem xt vi mt trong cc bm khng hot ng mc d iu ny c th c x l bng cch s dng nhiu bm hn mc song song hoc ni tip ti cc trm bm. Phn tch tin cy tng th phi c thc hin nu chi ph chi tit l yu t quan trng. 2.4 La chn kch thc ng

Cc yu t cn c xem xt trong la chn kch thc tuyn ng l: - Nng sut thit k. - Nng sut ngu nhin. - Vn tc sn phm. - Tui th lm vic ca p sut ging. - S ti u ho cc yu t ng knh, p sut, b dy ng.

Cc yu cu v thu lc dng chy v tn tr ca sn phm s c s dng trong vic nh gi s b ng ng knh. 2.5 La chn vt liu

S r r t cc ng ng l iu khng th chp nhn c v yu t thng mi ln yu t an ton v nhim mi trng. iu ny dn n vic vn chuyn cc lu cht nh vy i hi h thng ng ng phi c s ng b cao nht, c kh nng chu c p sut thch hp m khng c nguy c h hng.

tr gip ngi thit k trong qu trnh la chn vt liu, cc tiu chun cng nghip c to ra theo phn loi vt liu v qu trnh sn xut p ng cc yu cu phm cht hot ng, cc mc chp nhn c, bn, kim sot dung sai v kch thc Ngoi ra, hng lot cc tiu chun k thut cng ngh cng c h tr nhm pht trin v hon thin cc tiu chun cng nghip tho mn cc yu cu c th trong cng nghip du kh. Cc tiu chun k thut cng ngh xc nh cc yu cu k thut cho qu trnh thit k, mua bn, v lp t cc thit b ph tng ng ng khc nhau.

Cc yu cu v hiu qu cn phi c la chn i vi vt liu v phng php hn. S hiu bit thu o v nh hng ca cc tiu chun thit k i vi h thng ng ng cui cng l rt cn thit. T y, cc tnh cht c hc v


ho hc, dung sai kch thc c th c xc lp. Cc yu cu c bit i vi h thng nh kh nng chng n mn v cc yu cu v lp t, xy lp cng nh hng lin i n qu trnh thit k khi nim.

Thng ng c ch to bng thp, tuy nhin vic s la chn b hn ch do cc chng loi thp c s dng tho mn cc yu cu k thut. S la chn thp thng thng c xu hng chn sn phm c ch tiu k thut cao hn v l do kinh t.

Khi cn phi hon thin hn cc c tnh k thut ca ng thp carbon. C th s dng thp khng r, ng c bc ngoi hoc lt bn trong. Cc vt liu c bit nh vy hin nay gi thnh cn kh cao so vi thp carbon, tuy nhin khi k thut sn xut tr nn tin tin hn th gi thnh ca chng c th gim.

Cc vt liu phi kim loi v composite c sn sut cho cng nghip du kh dng cc ng do v cc ng c lt nhiu lp polymer. Vic s dng cc ng c lm hon ton t vt liu polymer rt ph bin i vi cc h phn phi kh p sut thp. Vt liu polymer c xem l vt liu hng u cho vic vn chuyn kh khi ri ro b ph hoi t pha th ba khng ln. 2.6 La chn b dy ng

Cc tiu chun thit k ca cc quc gia khc nhau a ra cc tiu chun k thut khc nhau cho vic la chn b dy ng vn hnh c p sut. Khi la chn cc loi ng s dng cho cc nhu cu c bit, cn phi quan tm n hin tng tng p t ngt, c bit trong trng hp trong h thng khng c thit b x l hin tng ny.

Cc yu t nh hng n b dy ng: - Ap sut thit k - Nhit thit k - n mn - Phng php lp t - a hnh y bin - n nh - Tui th thit k ca h thng ng ng

Cc iu kin vn hnh v p sut cng c tc ng n vic chn ng sut bn ca vt liu theo yu cu b dy ng.

C s khc nhau v mt s dng ng ng t lin do cng tc sa cha d dng hn v t tn km hn so vi mi trng ngoi khi. mi trng ngoi khi, xu hng chung l thc hin cc tnh ton thn trng i vi cc yu cu cho b dy ng. Tuy nhin cng phi cn thn trong trng hp ng ng t lin khi la chn tuyn ng v nghin ca gn nhau ti cc v tr c bit. V d cho trng hp ny l b dy ng ti trung tm dn c v trn cc nng tri phi c kh nng chu c cc va chm c hc vi cc thit b o t.

Nu ng c ng knh ln th qu trnh thit k ng cn phi xem xt cn thn cc ngoi lc tc ng ln ng, cng nh kim sot cn thn qu trnh lp ng. iu ny c bit quan trng i vi ng mng chu p sut ca t m khng b nh hng v trn v tnh ton vn ca cu trc. Cc ng thp c t l ng knh/b dy vt qu 96 phi c kim sot cn thn.


Vic p dng b dy cho php n mn c th c tnh n nu c s hin din cc cht n mn cng vi nc:

- CO2 n mn ngt - H2S n mn chua - O2 n mn oxi ho bng oxi

Mc n mn c kim sot bi cc bin c vt l sau: - Nhit - p sut - dn - pH - Nng cht n mn - Tc dng chy

Ngoi ra n mn chu tc ng ph nh: - Trnh cn thp - Cc loi ng sut (c nh v chu k) - Qu trnh x l nhit - Lin kt ca cc kim loi

Cc ng b n mn tc thp c th c x l bng b dy b sung cho php n mn. Trng hp n mn tc cao hn c th c x l bng cch s dng cc cht c ch n mn hoc s dng vt liu thay th thch hp. Cht c ch n mn khng th t hiu sut bo v 100%, do vy ngi thit k phi lu n iu ny khi dng chng khng ch hin tng n mn. Tng tc lin kt gia sn phm v cht c ch n mn phi c gii qut mt cch ring r. Trng hp c hoc khng c s dng cht c ch n mn th tng cc b dy n mn cho php khng c vt qu 6mm v n mn thng thng khng th c gi tr cao nh vy.

Trong qu trnh t ng th ng c th chu cc ng sut un trong qu trnh thao tc cng nh khi ng tip xc vi b mt y ca rnh. ng cn phi c b dy chng li cc ng sut un ny v hin tng on ng. 2.7 La chn lp ph chng n mn

ng ng c th b n mn t bn trong do lu cht sn phm hoc nc bm vo hoc t bn ngoi do tc ng n mn mnh ca cc iu kin n mn t t hoc nc bin.

Cc h thng lp ph ng ng thng c s dng l: - Cc lp ph bng nha ng c tng cng c tnh bng si thy

tinh hoc nha than . - Polyenthylene (PE) - Cc lp ph epoxy lin kt bng phng php nng chy (FBE)

2.8 La chn lp cch nhit

Trong qu trnh thit k khi nim nn xem xt n cc yu cu v cch nhit cho ng nu c. Lp cch nhit cho ng nhm gim lng nhit tht thot dc theo chiu di ng c th c yu cu cho mt s trng hp di y:


Lng tch wax (paraffin): Cc vn v nht cao c th xy ra do ngun gc du th khai thc ti

cc vng khc nhau c th cha t l ln wax (paraffin), c khi ln hn 5% khi lng. nhit thp (thp hn im vn ccloud point) c th xy ra hin tng hnh thnh cc tinh th wax lng ng trn thnh ng lm gim hiu sut vn chuyn hoc c th lm tc nghn ng ng. Cc kt ta wax c th c x l bng cc phng php lin tc nh bm ha cht, duy tr nhit hoc thng thng nht l dng thoi co ng ng (pig). Cc k thut gin on (off-line) khc c th c s dng nh ngm ra ng ng bng xylene hoc thi sch ng bng kh nhng cc bin php ny cng c nhc im ln l tht thot sn phm trong qu trnh ngng hot ng nh my khi cc thit b can thip, v tin cy ca cc thit b nh vy khng bo m.

S hnh thnh hydrate: S hnh thnh hydrate trong kh c th b c ch bng cch duy tr nhit

trong ng cao hn nhit hnh thnh hydrate cng nh bng cch bm methanol hoc glycol. Vic vn chuyn cc ha cht ny n u vo ca ng ng s i hi: s dng cc bn cha hoc cc h ng ng b sung v thng i hi phi c thit b tch cui ng ng hoc cc thit b x l.

La chn lp cch nhit: Mt s loi du th c nht rt cao nhit ng ng thng thng

v i khi nu c nc ln vo th c th hnh thnh nh tng c nht cao. C ba bin php c th xem xt la chn mt cch ring r hay kt hp vi nhau di y:

Tng ng knh ng, mc d iu ny c th tim tng nguy c n mn hoc cc vn ng cn trn ng ng khi vn hnh do tc dng chy b gim.

Bm thm ha cht lm tng kh nng vn chuyn hoc ha cht ph h nh tng. Cc ha cht ny thng t c th i hi vic lp t thm cc ng ng hot ng ph tr hoc cc li trung tm c bit khi khai thc di y bin.

Duy tr nhit dng chy bng cch s dng lp cch nhit v cc thit b gia nhit du hoc thit b b nhit. Chn ng cng l mt bin php quan trng lm tng kh nng cch nhit mc d i vi ng ng ngoi khi phng php ny c th kh thc hin hoc i hi chi ph cao.

Tiu chun k thut khi giao nhn p ng cc yu cu nguyn liu u vo cho cc thit b ch bin cui

ng ng, thng lu cht phi tha mn thng s ti thiu no v p sut nhit . Trong trng hp khng th p ng nhit v p sut yu cu c th dng cc bin php x l nh lp t thm thit b gia nhit v cc thit b tch b sung hoc c th cch nhit ng ng.


2.9 Vng b dn n Trc khi bt u thit k c mt s thng s cn phi c nh gi v

phn tch nhy. Cc ng ng v phn b dn n thng c x l theo tiu chun tha

mn ng sut. Cc thit b b dn n ngoi khi phi chu cc ti trng dn n v cc ti

trng ca dng chy cng nh sng. Tt c cc loi ti trng u c th c lm gim. Dn n nhit c th c lm gim bng cch s dng phng php lp t ln cht (nh chn v ln ngoi bin) hoc tng trng lng ng (s dng neo v lp ph btng). Ti trng ca sng c th c lm gim bng cch chun b cc nh che chn hoc dng cc tm ph. 2.10 La chn phng php bo v chng n mn

Cc ng ng ngoi khi thng c bo v bng cc loi anode hy sinh trong khi ngc li i vi ng ng t lin thng s dng h thng cung cp dng in t ngun ngoi.

Loi, kch thc v khong cch cc anode phi c xc nh nhm xem xt cc vn sau:

- Khi lng ca vt liu anode phi bo v ng ng trong sut qu trnh hot ng ca h thng ng ng, lun phi lu n thng s in tch ti a cc lp ph b nt gy hay ph hng trong qu trnh vn hnh ng.

- Din tch b mt ca cc anode phi ln cung cp cng dng in bo v ng ng cho ti thi im cui cng ca tui th lm vic ca ng ng, lc hu ht cc anode b tiu hao trong qu trnh hot ng.

- Khong cch gia cc anode c xc nh c c kch thc thch hp cho anode. Nu cc anode c lp t vo ng trn mt x lan t ng ngoi khi th chng phi c trng lng gii hn. B dy ca anode c th c xc nh bng chiu dy ca lp ph betone to trng lng.

2.11 Phn tch ct ng

D liu c bn v cc yu cu ca pha th ba i vi cc v tr ct nhau ca ng nn c kim tra trong giai on thit k khi nim.

Mt s im cn xem xt i vi ng ng ngoi khi l: - Gc ti im ct nhau. - Chiu cao yu cu ca ct d, cc im tip xc ng ti v tr ct nhau v hnh dng tng th ca ng ti v tr ct nhau.

- Chiu di ca on ng t do v n nh ca n. - Kh nng chu ng ca ng i vi hin tng ct xoy v cc ti trng mi trng.

- Kh nng chu ng ca t v khuynh hng b ln ca bt k ct . - Ngn nga hin tng ng b on ln. - Dung sai t ng i vi vic chun b ct nhau ca ng.


- Cc ti trng khi t ng, trong iu kin th thy lc, v trong iu kin vn hnh.

- Cc ti trng xut hin do qu trnh ln, m ti v tr ct nhau. - Kh nng b ph hy bi neo ca cc tu nh c. - Cc yu cu ca cc ngi vn hnh, ngi ch ng ng ca pha th ba.

Cc ng ng t lin i hi cc xem xt c bit bi khi nghin cu gn nhau v nghin cu tuyn ng c th xut hin cc yu cu cho ng ng ti v tr ct nhau vi cc c trng v a l v dn c khc nhau. Cc c trng c th bao gm:

- Cc ng ng khc, thng ct qua rnh hoc mng, tuy rng xem xt v vn b sung b dy ng hoc c b dy ng c bit. S tng tc ca h thng bo v ng ng bng dng in ngoi cng phi c nh gi cn thn.

- Cc v tr ct nhau qua sng hoc ca sng cng yu cu vic p dng cc k thut ko ng, v bn thn ng thng i hi phi c lp ph trng lng.

- Cc v tr ct nhau qua ng b v ng st c th i hi cc k thut nh lm cu vt, bc ng hoc lm ng hm, tuy rng vic thi cng c th lm gin on giao thng nhng vn nn xem xt vic s dng phng php o h.

- Cc ch ct nhau vi vng ly hay vng m ly c th bao gm vic ph trng lng cho ng, lm b mt ng tm thi v nhp b sung vt liu san lp.

Cc v tr ct nhau c th p dng phng php khoan nh hng. Phng php ny bao gm vic khoan t u ny sang u kia, gi cho l m bng btng, ko ng qua l s dng dy khoan. K thut ny kh thng dng i vi cc v tr ct nhau vi sng, c khong cch ln hoc c mt lu thng ln. 2.12 Lp lch trnh

Thit k khi nim nn quan tm n cc yu cu lch trnh xy lp ng ng.

Cc ng ng t lin thng phc tp do phi ct qua qu nhiu ranh gii ca cc ch t khc nhau. Cc sp xp c bit cn phi c thc hin c quyn i li, s cho php s dng t, lm ng cng sm cng tt trc khi tin hnh cc hot ng xy lp ng ng. Thit k khi nim nn quan tm n s pht trin ca k hoch thc hin d n s b trong chi tit ha cc yu cu lch trnh ca tt c cc hot ng din ra trong thi gian di.

Cc t l thi gian trong vic ch to gin v lp t, qu trnh xy lp trm t lin c th tham kho t trnh t cc hot ng trong vic pht trin mt m ngoi khi. Thng l khung thi gian c th cho qu trnh lp t ng v lin kt thit b lin quan n cc thi im khc nhau trong nm, s c sn ca cc x lan lp t, thi gian xy dng v thi gian lp t, v tr x lan t ng, v tr v kiu neo cho cc gin ni v cc tu trong khu m.


Thi gian cp php, thng tho vi ch s hu ca cc l khai thc khc, hoc cc i tng s dng vng bin khc cng thng ng vai tr rt quan trng.

Thit k chi tit nn c thc hin trc khi lp t, tuy nhin cc mt hng thit b i hi thi gian ch to v t hng tng i lu nh van, bch, b phn ni cn phi c xc nh, thit k v ch nh trc cho qu trnh mua sm thit b sao cho vic giao nhn cc thit b nh vy c th c thc hin trc khi cng vic ch to v lp t c bt u. Do vy thng phi bn bc gii quyt dt im trong qu trnh thit k khi nim cc vt t thit b quan trng i hi thi gian di nh vy (thng cc loi vt t ny c chi ph cao) v mt mua sm thit b. Trong trng hp ny, lch trnh chnh xc v c tnh p ng thc t l2 yu t quan trng ti a ha tnh hu dng ca thit k khi nim.

3. Thit k c kh cho ng ng

ng ng phi c bn chng li cc ti trng tc ng ln n, trong

qu trnh xy lp v th nghim ng ng v khi ng ng a vo vn hnh. Trong qu trnh xy lp, ng s b un, ko v xon. Khi ng a vo vn hnh n s b tc ng bi p sut bn trong t lu cht v t bn ngoi bi mi trng bin v t xung quanh, ngoi ra cn c cc ng sut gy ra bi s thay i nhit .

ng ng c th chu ti trng bn ngoi, chng hn ng di bin, ti trng l cc va chm vi neo, neo li c, vi trng hp ng trn t lin, ti trng ngoi c th l s lng xung khc nhau ca t xung quanh ng, ti trng to ra t cc phng tin giao thng trn nh ng, hoc l va chm vi cc thit b o t.

Cc yu cu v bn cho cc ng ng ngoi bin thng cao hn so vi ng ng t lin.

Vn c trnh by sau y p dng khi thit k bn chng li p sut trong, p sut ngoi, ng sut dc trc, hin tng un ng, hin tng va chm v mp ng, hin tng un ng cong ln. 3.1 Thit k chng li p sut bn trong

p sut bn trong to ra t lu cht vn chuyn trong ng l ti trng quan trng nht cho mt ng ng. Trong trng hp in hnh, mt ng 30 inch chu p sut trong 15Mpa chu ti trng tng l 11MN trn mi mt ng ng, th khi mi mt ng ng chu mt lc vng c ln l 5.5MN. Ngoi ra, ng sut vng to ra bi p sut trong c xc nh ch yu bng phng php thng k sao cho khng xy ra tnh trng ti phn b ng sut no ln v ng sut khng b b sung hoc lm suy gim bi ng sut n hi.

Nu ng sut vng qu ln, ng ng c th b on theo hng chu vi, hin tng on din ra tip theo s lm mng ng ng v cui cng gy gy ng.


Cng thc n gin nht tnh ng sut vng sH gy ra bi p sut trong l phng trnh Barlow:

t

pDsH 2

=

vi p l p sut trong, D l ng knh ng, t l b dy ng.

Cng thc ny khng c chnh xc kh tt. Kt qu tnh t phng trnh ny thng cao hn ng sut ti a, do vy nhiu quy tc chp nhn phng trnh ny khi thit k. Cng thc ny c th c vit li cho b dy ng l thuyt tho mn yu cu v ng sut vng gi tr tng ng sut n hi nh sau:

Yff

pDt

212=

Vi: Y l ln ca ng sut n hi ca vt liu lm ng. f1 l h s thit k, din t ng sut vng ti a cho php l tch s ca ng sut n hi.

f2 l h s dung sai ch to ng, cho php s sai lch ca b dy ng so vi b dy danh ngha, thng l 0.875, c ngha l b dy c th thp hn b dy danh ngha ti a cho php l 12.5%.

H s thit k hay l h s s dng hay h s hu dng thng ly gi tr 0.72 cho ng ng v ly gi tr thp hn cho ng ng v cc on ng gn vi gin ngoi khi hoc cc vng b hn ch hay cc tuyn ng giao thng i vi ng ng trn t lin.

Cc quy tc ch nh mt cch khc nhau cc gi tr ti a cho h s thit k, tu thuc vo v tr a l v cc xem xt xc ng khc.

V d i vi ng ng 30 inch th D = 762mm; p = 15Mpa; Y = 413.7 N/mm2; f1 = 0.72; f2 = 0.875 v t = 21.9mm tnh ton theo cng thc trn.

Trong thc t thng thng, kch thc ng ng c la chn tun theo tiu chun API. B dy k tip trong tiu chun API l 22.2mm, nn c th chn b dy ny cho ng trn. Trong trng hp c bit ng ng c th c ng knh v b dy bt k. V d trong trng hp ng ng ln v di th tit kim chi ph so vi s dng ng ng theo API l kh ng k. 3.2 Thit k chng li p sut ngoi

p sut bn ngoi ln c khuynh hng lm cho ng ng tr nn oval v cui cng l ph hu chng.

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