Kev siv thiab sealing qhov yuav tsum tau muaj ntawm qhov kub thiab txias valve yuav ua li cas xaiv cov khoom ntawm qhov kub thiab txias valve
2. Qhov cuam tshuam ntawm qhov kub thiab txias ntawm qhov kev sib khi ntawm lub valve
2.1 Non-metallic sealing khub
Pob li qub thiab npauj npaim li qub ua haujlwm ntawm chav tsev kub feem ntau siv hlau rau cov khoom tsis yog xim hlau foob ua khub. Vim lub siab elasticity ntawm cov ntaub ntawv uas tsis yog-hlau, qhov tshwj xeeb siab xav tau rau sealing yog me me, yog li lub sealing zoo. Txawm li cas los xij, ntawm qhov kub thiab txias, vim tias qhov nthuav dav coefficient ntawm cov ntaub ntawv tsis yog xim hlau yog ntau dua li cov ntaub ntawv hlau, qhov shrinkage ntawm qhov kub thiab txias thiab shrinkage ntawm cov hlau seals, valve lub cev thiab lwm qhov chaw muaj ntau qhov sib txawv, uas ua rau muaj qhov sib txawv. Kev txo qis ntawm sealing tshwj xeeb siab thiab qhov tshwm sim ntawm sealing tsis tuaj yeem raug kaw. Feem ntau cov ntaub ntawv uas tsis yog xim hlau khov thiab ua nkig ntawm qhov kub thiab txias, poob toughness, ua rau txias txaus thiab kev ntxhov siab so. Xws li roj hmab ntawm qhov kub qis dua nws cov iav kub, yuav plam elasticity, ua glassy, poob nws nruj. Tsis tas li ntawd, roj hmab tsis tuaj yeem siv rau LNG li qub vim nws muaj npuas nthuav dav hauv LNG nruab nrab. Yog li ntawd, tam sim no nyob rau hauv kev tsim ntawm qhov kub thiab txias valve, qhov dav dav yog qis dua -70 ℃ tsis siv cov khoom tsis yog xim hlau sealing auxiliary cov ntaub ntawv, los yog cov ntaub ntawv uas tsis yog-hlau los ntawm ib tug tshwj xeeb txheej txheem rau hauv hlau thiab non-metallic composite qauv hom.
Raws li cov ntaub ntawv txawv teb chaws, qee cov ntaub ntawv tsis yog hlau tuaj yeem siv tau zoo hauv lub xeev cryogenic. Nyob rau xyoo 1970, "slip shod", ib lub yas tshiab los ntawm Irish Alloy Co., LTD., yog ib hom ultra-high molecular hnyav polyethylene, uas muaj zog toughness ntawm -269 ° C, tsis tawg nyob rau hauv tej yam kev nyuaj siab, thiab khaws cia hnyav hnyav hnyav. Lub Mylar yas tsim nyob rau hauv Fabkis yog tseem elastic heev ntawm qhov kub ntawm cov kua hydrogen (-253 ℃). Lub polycarbonate foob tuav ntawm HT Lomanenko ntawm yav dhau los Soviet Union tau sim ua kua nitrogen (-196 ℃). Cov ntaub ntawv qhia tau hais tias cov polycarbonate muaj kev sib khi zoo ntawm qhov kub thiab txias.
2.2 Hlau foob khub
Nyob rau hauv qhov xwm txheej ntawm qhov kub thiab txias, lub zog thiab hardness ntawm cov ntaub ntawv hlau nce, plasticity thiab toughness txo, qhia txawv degrees ntawm qhov kub thiab txias nkig tshwm sim, cuam tshuam rau kev ua tau zoo thiab kev nyab xeeb ntawm lub valve. Txhawm rau tiv thaiv kom tsis txhob muaj kev ntxhov siab nkig ntawm cov ntaub ntawv ntawm qhov kub thiab txias, thaum tsim cov cua kub qis, ferritic stainless hlau cov ntaub ntawv feem ntau yog siv thaum kub siab tshaj -100 ℃, thaum kub qis dua -100 ℃, lub valve lub cev, valve npog, valve qia thiab sealing lub rooj feem ntau yog siv nrog lub ntsej muag-centered cubic lattice austenitic stainless hlau, tooj liab thiab tooj liab alloy, txhuas thiab txhuas alloy, thiab lwm yam. Tab sis vim hais tias Lub hardness ntawm aluminium thiab aluminium alloy tsis siab, qhov kev puas tsuaj thiab kev puas tsuaj ntawm lub sealing nto tsis zoo, yog li nws tsis tshua muaj siv nyob rau hauv qhov kub thiab txias valve. Feem ntau siv cov ntaub ntawv austenitic stainless hlau, feem ntau siv 0Cr18Ni9, 00Cr17Ni12Mo2 (304, 316L), thiab lwm yam, cov ntaub ntawv no tsis muaj qhov kub thiab txias txias qhov kub thiab txias, nyob rau hauv qhov kub tsis tshua muaj kub, tseem tuaj yeem tswj tau siab toughness.
Txawm li cas los xij, austenitic stainless hlau raws li qhov kub thiab txias valve hlau foob cov khoom siv kuj muaj qee qhov tsis txaus. Vim tias feem ntau ntawm cov ntaub ntawv no nyob rau hauv lub xeev metastable nyob rau hauv chav tsev kub, lub austenite nyob rau hauv cov ntaub ntawv transforms mus rau hauv martensite thaum qhov kub thiab txias yog qis dua theem hloov pauv point (MS). Rau lub cev nruab nrab qhov cubic lattice ntawm martensite ceev yog qis dua li ntawm lub ntsej muag-centered cubic lattice ntawm austenite, thiab vim hais tias qee cov pa roj carbon atoms npaj lub cev nruab nrab cubic lattice txoj hauj lwm tswj, ua rau cov lattice raws C axis kev loj hlob, yog li qhov nce ntawm lub ntim hloov. tshwm sim los ntawm kev ntxhov siab nyob rau hauv, ua Ameslikas tom qab sib tsoo ua tau raws li qhov yuav tsum tau sealing ntawm sealing nto buckling deformation, ua rau lub foob tsis ua hauj lwm.
Ntxiv nrog rau qhov deformation tsis ua hauj lwm ntawm sealing nto tshwm sim los ntawm qhov kub tsis tshua muaj theem hloov pauv, vim qhov kub ntawm qhov sib txawv ntawm txhua qhov los yog qhov sib txawv ntawm lub cev ntawm cov khoom sib txawv, ua rau tsis sib xws, qhov kub thiab txias ntawm qhov sib txawv yuav tshwm sim. Thaum qhov kev ntxhov siab qis dua qhov kev txwv elastic ntawm cov khoom, ib qho rov qab elastic distortion yog tsim nyob rau hauv lub sealing nto. Thaum qhov kub thiab txias ntawm ib feem ntau tshaj qhov kev txwv ntawm cov khoom siv, cov khoom yuav muaj kev cuam tshuam tsis zoo thiab deformation, uas yuav ua rau tsis ua hauj lwm ntawm sealing nto thiab cuam tshuam rau kev sib khi.
Nyob rau hauv qhov kev pom ntawm qhov kub thiab txias ntawm cov hlau sealing khub, cov kev ntsuas yuav tsum tau coj los ua kom lub deformation ntawm cov hlau sealing nto me me los yog deformation ntawm sealing nto tsis tshua muaj kev cuam tshuam rau kev sealing kev ua tau zoo. Ua ntej, hais txog cov ntaub ntawv, peb yuav tsum sim xaiv cov ntaub ntawv nrog kev ruaj ntseg ntawm cov qauv metallographic (xws li 316L tab sis nrog tus nqi siab). Thib ob, rau lub cev, npog, qia, foob thiab lwm yam khoom siv austenitic uas ua los ntawm cov khoom yuav tsum tau ua tiav ntawm qhov kub thiab txias, kom lub martensite transformation thiab deformation ntawm cov khoom yog tag nrho ua ntej ua tiav. Qhov kub ntawm qhov kev kho cua kub yuav tsum qis dua cov khoom siv theem hloov kub (MS) thiab qis dua qhov ua haujlwm kub ntawm lub valve, thiab lub sijhawm kho yuav tsum yog 2 ~ 4h. Yog tias tsim nyog, ntau qhov kev kho kub qis lossis kev kho kev laus tsim nyog tuaj yeem ua tiav. Ntxiv rau cov kev ntsuas saum toj no, tus qauv tsim yuav tsum tau txiav txim siab los txo qhov cuam tshuam ntawm kev sib khi deformation ntawm kev sib khi, xws li hauv kev tsim cov rooj vag li qub, pob li qub thiab npauj npaim li qub tuaj yeem xav txog kev siv cov qauv sib khi, yog li. tias qhov kub tsis tshua muaj deformation tuaj yeem raug them nyiaj ib nrab. Rau lub ntiaj teb valve yuav tsum yog conical foob qauv, kom tsis muaj kub deformation ntawm sealing nto ntawm me me cuam tshuam.
3. Kev cuam tshuam ntawm qhov kub thiab txias ntawm qhov kev sib khi ntawm lub valve
3.1 Stem packing
Vim qhov tsis xws luag ntawm cov khoom siv roj hmab ntawm qhov kub thiab txias thiab txias txias tshwm sim ntawm feem ntau cov ntaub ntawv uas tsis yog xim hlau, lub sealing tsim ntawm qia thiab lub valve lub cev ntawm qhov kub thiab txias valve tsis tuaj yeem siv daim ntawv sealing nplhaib, tuaj yeem tsuas yog siv lub thawv ntim sealing qauv thiab lub tshuab nqus tsev sealing qauv. General bellows foob yog siv nyob rau hauv nruab nrab tsis tso cai rau trace to thiab tsis haum rau packing lub sij hawm, lub neej ntawm nws ib txheej txheej yog luv heev, tus nqi ntawm ntau txheej txheej yog siab, kev ua yog nyuaj, yog li feem ntau tsis. siv.
Lub sealing qauv ntawm lub thawv ntim khoom yog ib qho yooj yim rau kev tsim thiab txheej txheem, yooj yim los tswj thiab hloov, thiab yog ib qho zoo heev hauv kev siv tswv yim. Txawm li cas los xij, kev ua haujlwm kub ntawm cov ntim tsis tuaj yeem qis dua -40 ℃. Txhawm rau kom ntseeg tau tias kev sib khi ua haujlwm ntawm cov ntim khoom, lub thawv ntim khoom ntawm lub valve qis qis yuav tsum tau ua haujlwm nyob rau hauv qhov chaw ze rau qhov kub thiab txias. Thaum tsis tshua muaj kub, nrog rau qhov txo qis ntawm qhov kub thiab txias, elasticity ntawm cov muab tub lim maj mam ploj mus, thiab cov dej-pov thawj kev ua tau zoo txo. Raws li kev tshaj tawm tawm los ntawm kev ntim khoom thiab lub valve qia dej khov, yuav cuam tshuam rau kev ua haujlwm ntawm lub valve qia, tab sis kuj yog vim qhov txav ntawm lub valve qia yuav packing khawb, ua rau kom loj heev. Yog li ntawd, nyob rau hauv ib txwm muaj xwm txheej, qhov kub tsis tshua muaj valve ntim yuav tsum tau ua haujlwm ntawm qhov kub siab tshaj 0 ℃, uas yuav tsum tau tsim lub caj dab ntev valve npog qauv, kom lub thawv ntim kom deb ntawm qhov nruab nrab kub tsawg, thiab xaiv cov ntim. nrog cov yam ntxwv ntawm qhov kub thiab txias. Feem ntau siv cov fillers yog polytetrafluoroethylene, asbestos, impregnated polytetrafluoroethylene asbestos hlua thiab saj zawg zog graphite, ntawm cov uas, vim asbestos tsis tuaj yeem zam permeability to, polytetrafluoroethylene linear expansion coefficient yog loj heev, txias txaus tshwm sim loj heev, yog li feem ntau tsis siv. Saj zawg zog graphite yog ib qho zoo heev sealing khoom, roj, kua yog impermeable, compression npaum li cas yog ntau tshaj 40%, resilience yog ntau tshaj 15%, kev nyuaj siab so yog tsawg tshaj li 5%, qhov qis fastening siab yuav muab kaw. Nws kuj muaj nws tus kheej lubricity, siv raws li lub pob valve tuaj yeem tiv thaiv kev ntim thiab valve qia hnav, nws qhov kev sib khi zoo yog qhov zoo dua li cov khoom siv asbestos, yog li nws yog ib qho zoo tshaj plaws sealing cov ntaub ntawv.
Vim hais tias cov muab tub lim feem ntau yog cov khoom siv tsis yog xim hlau, cov kab sib txuas nthuav dav yog ntau dua li cov hlau muab tub lim thiab lub valve qia. Yog li ntawd, thaum lub packing sib sau ua ke nyob rau hauv chav tsev kub poob mus rau ib tug tej yam kub, nws shrinkage yog ntau dua li ntawm lub packing qhov thiab lub valve qia, uas tej zaum yuav ua rau to vim qhov txo ntawm preloading siab. Nyob rau hauv kev tsim, lub packing gland bolt yuav preloaded nrog ntau pab pawg ntawm disc caij nplooj ntoos hlav gaskets, thiaj li hais tias lub preloading quab yuam ntawm packing ntawm qhov kub thiab txias tsis tu ncua compensated los xyuas kom meej lub sealing nyhuv ntawm cov packing.
Qhov qis qis ua ke cov qia ntim khoom tsim los ntawm Garlock Company hauv Tebchaws Meskas, lub nplhaib kawg yog ua los ntawm carbon fiber braided disc cag, lub nplhaib sealing yog ua los ntawm siab purity pob zeb diamond zoo nkauj graphite sawb molding, los ntawm lub khob thiab lub khob hliav qab thiab radial expansion. cov yam ntxwv, kom cov sealing kev ua tau zoo dua.
Qhov kub tsis tshua muaj deformation ntawm cov khoom qia yuav cuam tshuam qhov kev ua tau zoo ntawm kev ntim khoom. Yog li ntawd, tib yam li lub cev valve, valve npog, sealing accessory cov ntaub ntawv, lub qia yuav tsum kuj cryogenic ua tom qab ua tiav, thiaj li yuav ua rau lub qis kub deformation yog me me. Tsis tas li ntawd, vim hais tias cov austenitic stainless hlau siv nyob rau hauv cov khoom siv cryogenic tsis tuaj yeem kho cua sov los txhim kho qhov tawv tawv, kev sib koom ua ke ntawm cov qia thiab cov ntim khoom muaj feem ntau yuav nkig ib leeg, ua rau cov xau ntawm cov ntim. Yog li ntawd, lub qia saum npoo yuav tsum tau plated nrog nyuaj chromium los yog nitride los txhim kho qhov tawv tawv.
3.2 Nruab nrab flange gasket
Ob qho tib si nruab nrab flange foob ntawm lub valve thiab kev sib txuas sab nraud ntawm flange kev twb kev txuas valve feem ntau yog nyob rau hauv daim ntawv ntawm gaskets. Txij li cov khoom siv gasket yuav harden thiab txo cov yas ntawm qhov kub thiab txias, gasket rau qhov kub tsis tshua muaj qhov xav tau ntau dua. Nws yuav tsum muaj kev ruaj ntseg sealing thiab rov qab los ntawm qhov kub thiab txias, tsis tshua muaj kub thiab kub hloov. Kev cuam tshuam ntawm qhov kub tsis tshua muaj siab rau kev ua haujlwm ntawm gasket sealing yuav tsum raug txiav txim siab.
Raws li feem ntau siv gasket sealing cov ntaub ntawv, lub ntsia liaj qhov rooj ntev, gasket thiab flange thickness yuav shrinkage raws li qhov kub thiab txias. Txhawm rau kom ntseeg tau tias qhov kev txhim khu kev qha gasket sealing ntawm qhov kub thiab txias, nws yuav tsum tau ntsib
Δ HT3 Δ HT – Δ HT1 – Δ H1 Ntaus hauv
ΔH1 - Tensile deformation ntawm bolt sib dhos, mm
Δ H1 = 1 / E1H sigma
ΔHT1 - Bolt shrinkage nyob rau hauv qhov kub thiab txias ntawm ΔT, mm
Δ HT1 Δ T = H alpha 1
ΔHT - shrinkage ntawm gasket nyob rau hauv ΔT kub cheeb tsam, mm
Δ HT = alpha 2 Δ h T
ΔHT3 - Shrinkage ntawm sab sauv thiab qis flanges nyob rau hauv ΔT kub cheeb tsam, mm
Δ HT3 = alpha 3 Δ T1 (H – H)
σ1 - Bolt preload, N / mm
E1 - elastic modulus ntawm ntsia liaj qhov rooj, N / mm
α1, α2, α3 - yog linear expansion coefficient ntawm bolt, gasket thiab flange cov ntaub ntawv, feem, mm / m
H, H – mm
Thaum lub gasket foob mus txog qhov tsim ua hauj lwm qis kub los ntawm chav tsev kub, cov sum ntawm lub shrinkage ntawm lub sab sauv thiab qis flanges thiab lub shrinkage ntawm lub gasket yuav tsum tsawg tshaj li cov sum ntawm lub shrinkage ntawm lub ntsia liaj qhov rooj thiab tensile deformation ntawm lub ntsia liaj qhov rooj. kev sib dhos, txhawm rau xyuas kom meej tias lub gasket tseem muaj ib feem ntawm preload ntawm qhov ua haujlwm kub thiab tuav lub peev xwm sealing.
Yog li, plaub yam yuav tsum tau txiav txim siab hauv kev tsim. ① Lub ntsia liaj qhov rooj yog ua los ntawm cov khoom siv loj dua linear expansion coefficient, uas muaj shrinkage loj dua ntawm qhov kub thiab txias. ② Lub flange yog ua los ntawm cov khoom siv nrog me me linear expansion coefficient kom txo ΔHT3. ③ Txo cov thickness ntawm lub gasket, thiab siv cov khoom nrog me me linear expansion coefficient raws li lub gasket. (4) Ua kom cov tensile deformation ntawm bolts.
Rau qhov kub tsis tshua muaj qis dua -100 ℃, cov khoom siv lub cev thiab cov khoom siv ntsia liaj qhov rooj feem ntau yog ua los ntawm austenitic stainless hlau, linear expansion coefficient yog tib yam, yog li nws yog ib qho tseem ceeb los xaiv cov khoom siv gasket uas tsim nyog thiab ua kom lub zog tensile deformation ntawm bolts. Qhov zoo tshaj plaws kub tsis tshua muaj gasket khoom, nyob rau hauv chav tsev kub nws hardness yog tsawg, nyob rau hauv tsawg kub resilience yuav ua tau zoo, linear expansion coefficient yog me me thiab muaj ib tug tej yam mechanical zog. Hauv kev siv cov tswv yim, winding gaskets ua los ntawm stainless hlau daim kab xev ntim nrog asbestos los yog polytetrafluorethylene los yog saj zawg zog graphite feem ntau yog siv, thiab sealing nyhuv ntawm winding gaskets ua los ntawm saj zawg zog graphite thiab stainless hlau yog zoo tagnrho. Raws li rau qhov nce tensile deformation ntawm lub ntsia liaj qhov rooj, vim qhov txwv ntawm lub ntsia liaj qhov rooj installation preload, qhov nce ntawm cov npoo tsis ntau, yog li nws tuaj yeem txiav txim siab los teeb tsa lub disc caij nplooj ntoos hlav gasket los them.
Post lub sij hawm: Oct-19-2022
