BI 1: TNG QUAN V BN CHA DU KH

B mn Ha du K thut ng ng v b cha

CHNG 1: TNG QUAN V BNCHA DU KH1.1. Gii thiu.Trong cng nghip ha 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.

S tng th nh my lc du.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

1.2. Phn loi bn cha du kh

1.2.1. Phn loi theo chiu cao xy dng

B ngm: c t di mt t, thng c 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 1/2 chiu cao 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 ti ni khc d dng.So snh hai loi b ngm v b ni:B ngmB ni

- An ton: y l l do chnh v bo dm 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 i 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.

1.2.2. Phn loi theo p sut

B cao p: p sut chu ng trong b > 200mmHg.B p lc trung bnh: p sut = 20mmHg n 200mmHg thng dng b KO, DO.B p thng: p sut = 20mmHg p dng b du nhn, FO, b mi phao.1.2.3. Phn loi theo vt liu xy dng

B kim loi: lm bng thp, p dng cho hu ht cc b ln hin nay.u im:

- Kh b nt v, r r.

- Chu p sut tng i cao.

- Kch thc b khng hn ch.

- Ch to nhanh, lp rp v sa cha d dng.

Nhc im:

- D b g v n mn. Do vy tui th thp.

- Dn nhit tt lm tn hao bay hi du nh nhiu.

- Cha du nng th hiu sut gi nhit thp do mt mt nhit.B phi kim: lm bng vt liu nh: g, composit, nha, b tng nhng ch p dng cho cc b nh.u im: - Kh nng chu nhit tt khng b g nn tui th kh cao.

- Chi ph thp.Nhc im:

- Xng du ngm qua btng tt nn cn gii quyt tt vn chng ngm khi lm bng btng.

- p sut chu khng cao.

1.2.4. Phn loi theo mc ch

Bn trung chuyn.

Bn cp pht.1.2.5. 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 CHABn cha trong ngnh du kh ch yu dng cha cc sn phm nhin liu nh: kh, xng, DO v cc nhin liu ngnh ha 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 cc 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 gm cc bc sau:

2.1. 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 v vic lp t cc thit b trn bn cha.

2.2. 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, tu 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 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 la chn 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 dnh c ng sut tng ng ca n, y l thng s quan trng tnh chiu dy ca 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.2.3. 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 HTrong :

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 c gi tr:

Propan : 18 (at)

Butan: 9 (at)

Bupro: 13 (at)

2.4. Xc nh cc tc ng bn ngoi bao gm:

Cc tc ng bn ngoi bao gm:

2.4.1. Tc ng ca gi

Gi c th tc 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 nn nh ta xy dng tng bo v hoc t bn v tr kn gi.

2.4.2. 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 sn phm khng b tht thot ra ngoi, nhng vic ny 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 nn chn khu vc n nh a cht xy dng

Cc ti trng ln n c th xy ra cng c xt n, chng hn nh 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 yu t bn ngoi do con ngi tc ng nh: o dt cc hot ng c th gy ra va p vi bn, cc hot ng 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 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.

2.5. 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 dy phn hnh tr (L)

Cc thng s v np bn cha: Loi np bn cha, chiu cao np bn cha.

2.6. Xc nh cc l trn bn cha

i km vi bn l h thng ph tr bao gm cc ca ngi, cc l dng lp thit b o nh nhit , p sut, mc cht lng trong bn, cc l dng lp cc ng nhp liu cho bn, ng xut liu, ng vt bn, lp t cc valve p sut, cc thit b o dt nng hi sn phm trong bn cha.

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

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

2.7. Xc nh chn v tai nng

Chn bn cha ta dung chn bng thp hn hay c th xy dng 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 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 .

2.8. Cc nh hng thy lc n bn cha.2.8.1. 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 sut 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 c th kt hp c th xut hin cho vic 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 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 hn cui cng v tt c cc 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 cha 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 nhit th nghim v ng sut 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 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.

2.8.2. 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 ca 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.

2.8.3. 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 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 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 CHA3.1. 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 v 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 hai 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 bo m kch thc b rng vai nh nht nn l 1m cho bn cha cao 15m v 1,5 m 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 t bit ring.

3.2. 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 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 btng 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 150mm dng lm m v chng thm.

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

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

3.2.1 Kho st v tr Nh ngi t vn a cht ng tin cy kho st vng t (hiu r dt ai a phng, c kinh nghim v vic t nn mng ). y l bc quan trng nh hng sut qu trnh thi cng.

3.2.2. Kim tra t

Ngi ta thng dng phng 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. Nhnh 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 15m hay nh hn, ch cn tin hnh 1 php th gn khu trung tm ca nn mng v mt hoc hai l khoan ph. Chiu su ca php th DCPTs s ph thuc vo ng knh b cng nhiu 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 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

9CPTs i vi b c ng knh > 50m

su c xuyn qua khong gia c th t 3 - 5 m di sn ca nn mng, xc nh bn cht ca nn t ngay di nn mng.

3.2.3. Vt liu thi cng nn mng

3.2.3.1. Hn hp bitume- ct cho b 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

LoiKhong nhit

Shellmac 50/10065-95

Shellmac 150/20080-95

Shellmac 200/30085-105

Shellmac 300/40095-110

Shellmac 400/500100-115

Shellmac 500/700110-120

Shellmac S.125150-135

Shellmac SRO70-100

MC 80080-115

MC 300095-120

MC 365-95

MC 480-100

MC 5100-120

Mexphalte 80/100135-160

Mexphalte 60/70145-170

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 50mm.

Hn hp ct phi d dng lin kt v dng thit b 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.

3.2.3.2 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 t bit c pha ch sn vi tn thng mi l Shellmac SRO (Special Road Oil) vi nht t 40-50s STV (Stanrd Tag Viscocity) 25oC. 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 ha c phn tn vo ct trc khi vi SRO. Lng cht hot 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 hot 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 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 khng ng cng ca hn hp do tnh khng 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 i th s khng c tnh thm nc v phi loi b. Hn hp c em s dng v nn cht bng phng php tng t nh i vi hn hp ct kh v bitume.

3.2.4. ca bn cha

c dng gi sn phm trong khu vc c chn v ngn khng cho sn phm trn ra 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.

3.2.4.1. 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 ngay bn di ch xy tng.

3.2.4.2. 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 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 .

3.3. 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 xy dng thng c kinh nghim, ng vi mt trng hp c th h 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 nhn cng. Nhim v ca h l a ra mt quy trnh xy dng hon thin mang tnh kh thi, tha 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 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 tha mn.

3.3.1. Phng php hn hon thn 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 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 bn trn.

3.3.2 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 l cc tm ghp 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,vn 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.3.3.3. 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 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, t bit l hin tng mp bn.3.3.4. 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 ban u c gia cng xong. Dng thit b nng a mi gia cng vo bn trong. Sau , nc c bm vo bn, mi ni c 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 ni 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 thao tc cho cc tng thp bn trn.

Phng php ny ch c kh nng tc dng ti cc khu t c kh nng chng ln cao v tin on c kh nng chng ln ca n.

3.4. Cht lng mi hn :

Cht lng mi hn rt quan trng, n nh hng rt ln n cu trc ca bn, qu trnh vn hnh v tui th ca bn. Cht lng ca mt mi hn ph thuc vo rt nhiu nguyn nhn, trong c cc nguyn nhn chnh sau :

3.4.1. Trnh ca th hn :

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

Trong qu 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 tm kim loi ny l chng thm.

3.4.2. Cht lng ca qu trnh hn :

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

3.4.3. iu kin thi tit :

Qu trnh hn khng nn tin hnh trong iu kin thi tit m t hoc ma gi, bo, tuyt, ma 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 18 0C). Trong trng hp ny trc khi hn phi tin hnh 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 mt phm vi nht nh. i vi thp Cacbon hay thp c ng sut trung bnh v cao u phi c gia nhit trc theo nhng qui nh nht nh.

3.4.4. in cc hn v dy hn :

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

in cc hn phi c bo qun, gi gn trong thng cacton hay nhng ni kh ro trnh chu nh hng xu ca mi trng.Nu nh in cc hn b m t nhng khng b h hi g vn c th dng li khi c s ng ca nh sn xut. 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 hay nhng in cc cha t hydrogen s c dng cho lp hn nn, iu ny bt buc khi nhng tm kinh loi dy > 19mm hay khi nhit mi trng thp. in cc thp Hydrogen phi c bo v kh ro trc qu trnh hn y l yu cu ca nh sn xut. in cc thp Hydrogen c dng hn cc kim loi c ng sut trung bnh v cao.

3.4.5. Vt mp mi hn :

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

3.4.6. 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 v khng li du vt g khi tin hnh hn c nh.

Khi thi cng 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 m bo c tnh c, l v ha.

Gim c chi ph nhn lc v cc nhng thit b ph kin i km.

i vi thi cng bn cha th ch yu ch c 2 mi hn l hn dc v hn ngang.

Trong nhng mi hn gm nhiu lp, mi lp ca kim loi hn u phi c lm sch x v nhng cht kt lng khc trc khi tin hnh lp tip theo. Mi hn c hon tt khi mi hn c lm sch.

3.5. Trnh t thi cng bn cha

3.5.1. 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, c th c gia cng trc v sau c vn chuyn n cng trng thi cng bng 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 th thy lc sau bn c c nh ti v tr xc nh.

3.5.2. Quy trnh thi cng bn

3.5.2.1. 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 my neo cho cp khi thi cng tm ngh vo cui tun hoc ngy l, t bit lu i vi 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 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.

3.5.2.2 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 nynhng 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 xi 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 da san bng.

3.5.2.3 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.

3.5.2.4 Kim tra tnh u n:

Trc khi hn cc tm thp li vi nhau (khi hon thnh tng cui cng ni vi y), cn kim tra tnh u n thng hng v tn ti khe h hp l gia cc tm thp, bt c s sai lch no xc nh c trong qu trnh hn phi nm trong khong dung sai cho php. Nu ta tin liu c cc gi tr sai lch vt qu khong gi 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 qu trnh hn m bo 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 bin dng no khc. Khi bn c hon thnh, khng c php nn 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.

* D 12.5 m

= 13mm

* 12.5 < D 45m

= 19mm

* D > 45 m

= 25mm

3.5.2.5 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 ty theo kh nng chu lc ca tng loi ct m tnh ton cc s ct v b tr i xng nhng v tr thch hp. Khi cc ct c 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 cc cng on ny thng qua qu trnh hn cc b phn li vi nhau. Sau c th tho d 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 sao cho chng c sp xp i xng vi nhau qua tm bn. Mc ch ca qu trnh ny l ti trng c 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.

3.5.3. Cc phng php di chuyn bn

3.5.3.1. Di chuyn bn trn con ln:

di chuyn bn trn nhng con ln, trc ht phi nng bn ra nhng nn mng tm thi xung quanh chu vi ngoi vi 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, 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.

3.5.3.2. Di chuyn bn bng phng php ni:

Phng php ny c thc hin bng phng php 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 ln n nn mng chun b ti v tr mi v cho php t n nh cho php t n nh tr li khi ta tho nc ra khi mng.

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

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

gi c v tr vung gc vi mt nc trong qu trnh 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.

3.5.3.3. Di chuyn 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 d 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 CHA4.1. H Thng Bm

4.1.1. 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 lc tc dng ca lc ly tm khi cnh gung 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 thy 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 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 thp hn mc cht lng trong b ht cho cht lng t ng chong 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 bm mt cp ch t c p sut ti a 40 50m, cn mun tng p sut cht lng ln hn na th phi dng bm nhiu cp.

* u im ca bm ly tm:

- To mt 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 h hng v tc do bn gy ra.

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

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

- 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 cng th nng sut s gim mnh so vi thit k do hiu sut gim theo.

4.1.2. Bm th tch

Bm th tch l lai bm hat ng da trn c s s thay i th tch ca khng gian lm vic trong bm. Hai t im c bn ca bm th tch l:

Lu lng cht lng khng u v t ph thuc vo p sut ca bm.

Bm c th to ra p sut cao; gi tr p sut ph thuc vo cng sut ca bm. Trong bm th tch da vo c ch ca vic thay i th tch trong bm m phn ra thnh bm pittong v bm rto.4.1.2.1. Bm pittong

Bm pittong tc dng n c cu to gm xylanh hnh tr, trong c pittong chuyn ng tnh tuyn qua li nh c cu truyn ng tay quay thanh truyn. pha u xylanh c xupp ht v xupp y.

Khi pittong chuyn ng t tri sang phi p sut trong xilanh s gim xung nh hn p sut kh quyn, d tc dng ca p sut kh quyn xupp ht s m ra nc trn vo xylanh. Khi pittong chuyn ng ngc li t phi qua tri, p sut trong xylanh s tng ln; khi xupp ht s ng li. khi p sut trong xylanh ln hn lc nn ca l xo trn xupp y th xupp y s m ra v nc trong xylanh s c y vo ng dn. nh vy trong mt chu k chuyn ng ca pittong qu trnh ht v y cht lng c thc hin mt ln. khc phc hin tng lu lng ca bm khng u, ngi ta ch to bm pittong tc dng kp s ht v y cht lng hai ln trong mt chu k chuyn ng ca pittong. Ngoi ra trong k thut khc phc hin tng lu lng khng u nhi ta cn ch to cc loi bm pittong tc dng ba, tc dng bn

Hnh 4.1. S bm pittng tc dng n1 tay bin; 2 thanh truyn; 3 con trt; 4 cn pittng; 5 pittng; 6 xy lanh; 7 khoang cha; 8 ng y; 9- van y; 10- ng ht; 11- van ht; A - im cht trn (v tr bin bn tri ca pittng); B - im cht di (v tr bin bn phi ca pittng).

Hnh 4.2. Bm pittong c nhng u im ch yu l:

Cung cp lu lng cht lng c p sut ln

Khi ng bm khng cn mi cht lng

C th s dng vn chuyn nhiu loi cht lng c nht khc nhau.

Nhc im ch yu ca bm pittong l:

Bm c kch thc v khi lng ln, do vy chim nhiu din tch lp t.

Truyn ng phc tp, cc chi chng b mi mn.

Lu lng khng u.4.1.3 Bm Trc Vt

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

Bm c th c mt, hai, hoc ba trc vt t nm ngang hoc thng ng. Loi bm ba trc vt th trc gia l trc dn v hai trc hai bn l hai 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.4.2. H Thng Van (Valve)

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 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.

4.2.1 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

t tnh dng cht lng

Kn h thng

Yu cu tc ng

Chi ph ban u

Bo dng

4.2.1.1. Van cng hay van ca (gate valve)

Van c thit k v lm vic nh mt van chn. Khi lm vic, van loi ny thng ng hon ton hoc l m hon ton. Khi m hon ton, cht lng v 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 hnh a. Ngoi ra cn c mt s kiu van ci tin t hai loi a trn.

4.2.1.2 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, van x, bi ) nhng c th dng trong trng hp tn tht p 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 khin 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 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 li 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 i 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 thng sut.

Van phi chu p sut cao v thay i trong trong lnh vc tit lu phi c thit k 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, van.

Hot ng: a van truyn thng ngc vi a van cm, to ra lp tip xc 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 l cho van cu quay, a v hnh nhn thng c trng bng ng thau. Trong van cu bng thp dng n nhit vi 7500 F, van thng c m thp khng r. Cc b mt thng c ti luyn nhit t c gi tr cng khc nhau. Nhng loi vt liu khc, bao gm hp kim Coban cng c s dng.

B mt van l nn, m bo chc chn ton b b mt c tip xc c duy tr bi cc a kha 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.

4.2.2 Van iu chnh

Van diu 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 tha mn tn hiu t b iu chnh p sut, lu lng hoc nhit .

Yu cu u tin ca mt van diu chnh l iu chnh lu lng dng chy t v tr m n ng trong gii p sut lm vic m khng b ph hy. Nhng van thit k c bit nh cu kim, bm, bi, mng c kh nng p ng nhng yu cu trn mc khc nhau . Cc nh sn xut nn chn la gii hn lm vic cho tng loi van c th.

4.2.2.1 Van nt:

Van nt cn gi l van by, thng c s 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 c p dng ha cht lng. Van ht thng khng c thit k mt cch c bit c 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 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 ng ng. N c th c s dng trong lnh vc t p sut chn khng n 1000psi v nhit t -500F 1500 F. Cc van nt c th c trng vi rt nhiu vt liu khc nhau, ph hp vi nhiu ng dng cho ha cht.

4.2.2.2 Van dng mng:

Van dng mng c rt nhiu thun li trong 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 nhng c tnh lm kn tuyt vi.

Dng cht lng c ngn khi nhng phn lm vic ca van ngn chn tp cht, ha cht lng v s mi mn ca kt cu c kh. Bi v khng 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 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 t dng chy, mng van mn do to nn mt vng p lc phi trn van, mt my nn kh dng to mt vng 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 thy 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.

4.2.2.3. Van bi:

Van bi l van xoay 1/4 vng, ng dng cho kh, kh nn, cht lng v va xy dng. Vic s dng nhng vt liu lm kn, mm hay nylon, cao su tng hp, polime to ra kh nng l kn tuyt vi t - 450 5000 F.

Vn hnh van bi cng nh van ht, chng khng c mi ghp v to ra tt. 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 hoc m hon ton trong qu trnh xut nhp.

Nhng thnh phn chnh ca thn van, nt hnh cu v . Van bi c th c thit k ba dng: ca van ng Venturi, ca van 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.

4.2.2.4 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 cui 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.

4.2.2.5 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 1/4 vng t v tr ng n v tr m hon ton.

4.2.3 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 kiu a rn, van ch Y; trong van kim tra kiu ci u thng c s dng nht.

4.2.4 H thng x p

4.2.4.1 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 cc p lc trn cn bng, cht lng s chy ra qua ca van ra ngoi.

Cc van an ton thng c 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.

4.2.4.2 a ph hy:

Mt dng thit b x p t bit l a ph hy. Thit k thng l cc bch vi cc l p su bng my bt 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 hy cng c th c dng vi dng van an ton dng l xo. Bng cch s dng a ph hy x p sut p sut khong 5 -10% ln hn p lc t ca van an ton, a ph hy 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 hy cng c th c lp t gia van b phn cn c bo v.

Khi vt qu p sut thit k ca a ph hy, 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 hy. Khi lp a ph hy, 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 hy.

p lc thit k ca a ph hy khng th iu chnh c.

Cc thit b bm v van thng phi tha mn cc yu 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.

4.3. Dng c o

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

Cc thng s ha 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 ha trn b mt, nhit , p sut,

Cc thng s lin quan n vn vn chuyn nh lu lng, khi lng, mc cht lng,

Tt c cc thng s trn c nhiu hnh thc hin th khc nhau ty 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,

4.3.1 Thit b o nhit

Chng ta cng bit rng qu trnh truyn nhit xy ra ba hnh thc ch yu l i lu, dn nhit 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 thy 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

- Nhit k p sut l xo

- Cp nhit in

- Nhit k in tr

4.3.1.1 Nhit k lng kim

C ch hot ng ca loi nhit k lng kim c to bng cch nung chy cho hai thanh kim loi dnh vi nhau sau to thnh mt thanh hnh xon c. Di tc dng ca nhit , hai thanh kim loi 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 nhit k lng kim l:

Nhit nguyn t lng kim co gin kim ng h quay

Nhit k lng kim ng h dng xc nh nhit trong khong 1500C 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.

4.3.1.2 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 thy ngn) hay hn hp lng kh (thng l Nit). Di tc ng ca nhit th p sut trong bu tng ln do cht lng gin n hay p sut hi bo ha 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 .

4.3.1.3 Cp nhit in:

u im: ln nht ca cp nhit sang tn hiu in, t cc k s c th d dng x l tn hiu ny trong dy chuyn t ng ha 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 nhau 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 k 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 ca 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 nhit sn. V vy, milivn k ni vi cp nhit 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

4.3.1.4 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 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 c 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 cp nhit in. Qu trnh trn c th tm tt nh sau:

Nhit in tr hiu in th milivn k nhit c.

4.3.2 Thit b o p sut

p sut trong bn dng kim tra an ton ca bn kh cha cc sn phm kh ha lng. Trong mt s trng hp p sut cn xc nh lng kh ha lng trong bn. Mt 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.

4.3.2.1. ng Bourdon

L nhn t nhn bit p lc chung nht. y l mt ng kim loi dt bng phng, c bt kn u cui cng v c un cong thnh 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 n c tnh ca n. Trong bn b kn v bn b cha kh ha lng thng dng loi p k ng xon Bourdon.

4.3.2.2 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 milimet H2O n 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 bi mt lp n hi nh Teflon.

4.3.3 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 (Electricprobe)

Ngoi ra cn c cc loi o mc cht lng gin tip nh:

- Dng c o dng p sut thy tnh (Hidrostactic Pressure)

- Dng c o dng bc x (Radioactive Device)

- Dng c o s thay i khi lng (Closs Of Weight Divice)

4.3.3.1 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 gn bn, 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 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 ln 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.

4.3.3.2 Phao chim ch:

Nguyn tc hot ng ca loi ny da trn lc y Asimet. 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 Asimet 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 Asimet 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.

4.3.3.3 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 Asimet 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 trn bn. Khi phao ni th cm bin li iu khin bm cp liu cho 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 ha 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.

4.3.3.4 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 do ny dng kim sot mc cht lng mt v tr xc nh trc. Sau y chng ta xt nguyn tc hot ng ca ba loi u d in 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 qui nh hay cha. B tr u 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 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 phn cc bn t s h ra. Khi cht in mi l hi bo ha ca cht lng. Nh vy in dung ca t s thay i bo 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 role in. Role in ny c th dng diu khin bm, van, trong khi nhp hay xut liu.

Loi u d ny tuy c gi thnh cao nhng li t 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 in 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 mt mc thp v mt mc cao trong bn. Nu mun xc nh lin tc s dng ln ca cht lng th u d 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 ngi ta o su y bin. 4.3.3.5 Dng c o dng p sut thy tnh

Dng c xc nh mc cht lng da trn p sut thy 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 thy 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 thy tnh ln ng rut g gn trong ng h. C th dng cc lu cht khc nhng tt nht l dng khng kh v gi thnh r v lun c sn. Sau y l mt 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 thy 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 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 ha 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 thy ngn. Mt u ng thng vi y bn cha cht lng, u cn li thng vi khong khng gian cha hi bo ha trn bn. p sut thy tnh do cht lng gy ra mc thy ngn trong nhnh thng vi cht lng xung v lm mc thy ngn bn u cn li dng ln. Chnh lch mc thy ngn cho ta bit chiu cao cht lng trong bn cha.

4.3.3.6 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 ttrng 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 qui ra chiu cao mc cht lng.

4.3.3.7 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 t th ca sn phm du kh d bay hi v ty 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.

4.3.4. 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 du, 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

4.3.4.1. Ca ngi (Hole man)

Mi bn cha c 1- 2 ca ngi lp t trn thnh bn, c ch to cng loi 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.

4.3.4.2. 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 kc.

4.3.4.3. H thng lm mt:

Trong qu trnh tn tr, trong nhng iu kin nhit 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 ng cong theo thn bn pha trn np, dc theo ng ta khoan nhiu l trn cch u nhau cho nc c th lm mt ton b bn cha.

4.3.4.4. 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 phi dng phng php ni t thit b bng nhng cc tip t.

4.3.4.5. 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 rng 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 n 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.

4.3.4.6. 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 u trong khu vc. S dng cc thit b chuyn dng trong thao tc trnh tch in gy chy n.

Lp t h thng vi nc 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 (fire wall) 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 ti nc cho ton b bn cha bng 5 vi phun 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 sao 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 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 xy chy n. Vi kho tn tr c 100m2 phi c mt bnh cha chy. Vi nhng h thng phn phi phi c 1 hoc 2 bnh ti bn cha.CHNG 5: THIT K H THNG NG NG5.1. 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 thy lc nhng li hon ton khc nhau kha cnh khc, v d nh la chn tuyn ng, la chon dy ng

ng ng ngoi bin v t lin c cng mc tiu v mt an ton, tha 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 3 giai on:

5.1.1. 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 nguyn cu sau tr khi nh gi c rng d n c gi tr v nhy cm ca n thay i.

5.1.2. 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 sau 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).

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

- La chn thit k ti u v cc quy 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 v mt kinh t.

- Trch nhim ca giai on thit k khi nim phc tp hn v lin quan n tnh kh thi v mt k thut, ti u ha 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.

5.2. Thit k khi nim cho ng ng

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

5.2.1. Thit lp chun thit k

Ngi thit k phi lp dng ca c s d liu cho thit k, cc tiu chun cho thit k 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, quy tc, v cc tiu chun.

- Cc yu cu vn hnh.

- D liu v sn phm, d liu v quy 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 (thic b t l), cc mc v 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 liu v gin/trm.

Ti liu ny nn c 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.

5.2.2 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.

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