Qhov Kev Lag Luam Tseem Ceeb - tawm hauv Pressurized Glycol Loops
Kaw - voj cua sov tshuab siv monoethylene glycol (MEG) raws li khov- tiv thaiv cov dej hloov hluav taws xob yog muaj nyob rau hauv cov chaw sab nrauv, hnub ci thermal installation, thiab cov txheej txheem kev lag luam cua sov qhov twg qhov kub thiab txias poob qis hauv qab khov. Ib qho 20% MEG-hauv-dej tov muab kev tiv thaiv tawg mus rau kwv yees li -8℃thaum tswj kom tsim nyog viscosity thiab kub muaj peev xwm. Thaum 316 stainless hlau ncig cua sov ua haujlwm nyob rau hauv xws li kev daws teeb meem ntawm 110℃thiab 4 bar system siab, cov khoom ntsib ib qho kev txhoj puab heev tab sis feem ntau tswj tau ib puag ncig. Glycol daws ntawm qhov kub thiab txias maj mam oxidize rau cov organic acids (glycolic thiab oxalic acids), txo cov pH ntawm nruab nrab mus rau kwv yees li 5-6 lub sij hawm. Tsis tas li ntawd, cov pa oxygen yaj uas muaj nyob rau hauv thawj zaug sau tuaj yeem txhawb kev txhim kho hauv zos kom txog thaum cov pa oxygen tau noj los ntawm cov tshuaj tiv thaiv nrog glycol lossis raug tso tawm los ntawm lub tank expansion. Sheath thickness nyob rau hauv daim ntawv thov no tsis yog hais txog kev muaj sia nyob siab corrosion tab sis hais txog kev tswj hwm qhov sib npaug ntawm kev siab ncaj ncees, thermal efficiency, thiab lub sij hawm ntev tsis kam mus rau qeeb degradation uas tshwm sim ntau xyoo ntawm kev ua haujlwm tas mus li.
Kev xav tau ntawm lub nkoj siab thiab qhov tsawg kawg nkaus tus qauv phab ntsa
Ntawm 4 bar kev khiav hauj lwm siab, lub hoop kev nyuaj siab nyob rau hauv ib tug ncig lub rhaub sheath yog kuj tsawg. Rau ib tug raug 12 hli txheej txoj kab uas hla lub raj nrog 1.2 hli phab ntsa thickness, lub internal pressure stress yog xam siv lub nyias-wall cylinder formula σ=P⋅ri/tσ=P⋅ri/t, qhov twg PP yog lub ntsuas siab (4 bar los yog 0.4 MPa), riri yog 4 app. 1 mm rau sab hauv. phab ntsa), thiab tt yog phab ntsa thickness. Qhov no yields ib tug hoop kev nyuaj siab ntawm txog 1.6 MPa, uas yog negligible piv rau 316 stainless hlau yield zog ntawm kwv yees li 200 MPa nyob rau hauv chav tsev kub thiab 150 MPa ntawm 110 degree. Txawm tias muaj kev nyab xeeb ntawm 5, 0.5 hli phab ntsa yuav theoretically muaj lub siab. Txawm li cas los xij, cov cai ntawm lub nkoj siab xws li ASME Boiler thiab Pressure Vessel Code yuav tsum muaj qhov tsawg kawg nkaus ntawm phab ntsa thicknesses rau cov neeg kho tshuab robustness, xov kev koom tes, thiab kev tiv thaiv corrosion. Rau cov cua kub cua nrog cov xov los yog flanged sib txuas, lub sheath yuav tsum tiv tsis tau tsuas yog sab hauv siab tab sis kuj installation torques thiab thermal expansion stresses. Lub phab ntsa thickness qis dua 1.0 hli yuav muaj kev pheej hmoo ntawm cov xov stripping lossis lub raj tawg thaum sib dhos. Yog li ntawd, qhov tsawg kawg nkaus cov txheej txheem thickness rau 316 stainless hlau ncig lub rhaub nyob rau hauv 4 bar glycol kev pab cuam yog kwv yees li 1.0-1.2 hli, dictated ntau dua los ntawm txhua yam tuav thiab kev twb kev txuas kev ncaj ncees dua los ntawm lub siab tswj.
Glycol Degradation thiab Ntev -Lub Sijhawm Corrosion Allowance
Thawj qhov kev txhawj xeeb txog kev xeb hauv cov kev daws teeb meem kub MEG yog maj mam tsim cov organic acids los ntawm thermal oxidation. Thaum lub kaw lus muaj cov pa oxygen yaj- uas yuav luag ib txwm muaj tseeb rau lub voj voog tshiab los yog tsis zoo deaerated- glycol tawg ntawm qhov kub siab tshaj 90℃los tsim glycolic acid, oxalic acid, thiab formic acid. Cov kua qaub no txo qis pH thiab tuaj yeem tua cov yeeb yaj kiab passive ntawm 316 stainless hlau. Laboratory kev tshawb fawb ntawm 316 stainless hlau nyob rau hauv 25% MEG ntawm 110℃nyob rau hauv aerated tej yam kev mob qhia tsis zoo corrosion tus nqi ntawm 0.02-0.05 hli ib xyoo, nrog me ntsis siab dua tus nqi (0.05-0.10 hli ib xyoos) nyob rau hauv cov kua-vapor interface cheeb tsam uas oxygen concentration siab tshaj. Tshaj li kaum xyoo tsim lub neej, kev tiv thaiv corrosion ntawm 0.5-1.0 hli yog li ceev faj. Lub phab ntsa 1.2 hli yuav poob kwv yees li 0.2-0.5 hli nyob rau lub sijhawm ntawd, tawm hauv 0.7-1.0 mm-tseem muaj cov qauv tsim nyog tab sis nrog cov npoo me me rau kev ntxhov siab xws li huab cua nkag lossis cua sov hauv zos. Lub phab ntsa 1.5-1.8 hli muab kev tiv thaiv corrosion zoo dua thaum tseem tshuav thermal. Ntau insidious tshaj li niaj hnub corrosion yog qhov kev pheej hmoo ntawm crevice nres ntawm gasketed flanges los yog nyob rau hauv scale deposits. Glycol tawg cov khoom tuaj yeem ua polymerize los ua cov nplaum nplaum uas ntxiab kua qaub tiv thaiv cov hlau. Nyob rau hauv xws li crevices, pH tuaj yeem poob hauv zos mus rau 3-4, thiab tus nqi corrosion yuav ncav cuag 0.2-0.5 hli hauv ib xyoos. Lub phab ntsa tuab muab qhov loj dua kev nyab xeeb tiv thaiv qhov tob ntawm qhov kev tawm tsam tsis txaus ntseeg.
Thermal Efficiency thiab cuam tshuam ntawm phab ntsa Thickness ntawm Glycol cua sov
Monoethylene glycol solutions have lower thermal conductivity and higher viscosity than water, which already reduces heat transfer from the sheath to the fluid. Adding a thick stainless steel wall compounds this problem. For a 20 % MEG solution at 110 °C, the convective heat transfer coefficient in turbulent flow (Re >4000) yog kwv yees li 800-1200 W / m²·K, uas yog qis dua dej 1500-2500 W / m²·K. Lub sheath thermal kuj yog li ntawd sawv cev rau ib feem loj ntawm tag nrho cov thermal circuit tshaj nws xav nyob rau hauv dej. Ua kom cov phab ntsa thickness ntawm 1.2 hli mus rau 1.8 hli ntawm lub 12 hli txheej txoj kab uas hla lub raj tsa lub conductive kuj los ntawm kwv yees li 50%, uas ua rau ib tug 15-20% txo nyob rau hauv tag nrho cov tshav kub hloov mus rau tib yam twj tso kua mis. Qhov tseem ceeb tshaj plaws, cov phab ntsa tuab ua rau lub plhaub ntawm qhov kub siab dua rau tib lub zog nkag. Ntawm lub tshuab hluav taws xob sib xyaw ua ke watt ntom ntom ntawm 8-10 W / cm² ntawm lub plhaub saum npoo, 1.2 hli phab ntsa ua haujlwm hauv 110℃MEG daws tuaj yeem tswj qhov kub ntawm 135-140 degree. Lub phab ntsa 1.8 hli yuav thawb qhov ntawd mus rau 155-165 degree. Qhov kub siab tshaj 150℃nrawm glycol oxidation heev. Rau txhua 10℃nce siab tshaj 120 degree, glycol degradation tus nqi kwv yees li ob npaug. Yog li, lub phab ntsa tuab tsim los muab kev tiv thaiv corrosion tuaj yeem ua kom nrawm nrawm heev uas nws txhais tau tias los tiv thaiv los ntawm kev nce qhov kub hauv zos ntawm cov kua-sheath interface. Qhov kev tawm tswv yim ntawm tus kheej no txhais tau hais tias rau cov kev pabcuam glycol, cov phab ntsa nyias tsis yog tsuas yog siv tau zoo xwb tab sis kuj tseem tuaj yeem tiv taus corrosion ntau dua hauv kev xyaum vim tias lawv ua kom lub plhaub txias dua.
Tswv yim Thickness pom zoo rau txawv kev pab cuam
Rau qhov kaw -voj 20 % MEG system ua haujlwm ntawm 110℃thiab 4 bar, cov lus qhia tuab hauv qab no siv raws li kev tsim qauv thiab xav tau cov pa oxygen. Rau qhov zoo-deearated, kaw kaw nrog lub tank nthuav dav nrog nitrogen, qhov twg cov pa oxygen tau khaws cia qis dua 100 ppb, tus nqi corrosion yog tsawg (0.01-0.02 hli hauv ib xyoos). Lub thickness ntawm 1.2-1.5 hli muab lub neej kaum xyoo nrog cov paj loj. Cov phab ntsa nyias kuj ua rau cov tawv nqaij qis, txo qis glycol degradation. Rau lub kaw lus qhib uas ua pa cua los ntawm lub vented expansion tank, qhov twg cov pa yaj nyob rau ntawm cov qib saturation (kwv yees li 1-2 ppm ntawm 110 degree), tus nqi corrosion nce mus rau 0.05-0.10 hli ib xyoo. Lub thickness ntawm 1.6-1.8 hli yog pom zoo kom muab ib tug kaum-xyoo corrosion pub ntawm 0.5-1.0 hli. Txawm li cas los xij, cov phab ntsa tuab no yuav tsum tau ua ke nrog qhov txo qis watt ceev - tsis pub ntau tshaj 6-7 W / cm² - kom lub plhaub kub qis dua 150℃. Rau cov tshuab uas tau ntsib cov xwm txheej qhuav qhuav los yog qhov twg glycol tsis tau hloov, ua rau cov kua qaub siab, lub thickness ntawm 2.0 hli yuav raug tsim nyog, tab sis nyob rau lub sijhawm no lub thermal txim yuav hnyav heev. Nyob rau hauv cov ntaub ntawv no, hloov mus rau ib tug ntau corrosion-resistant alloy xws li 316Ti los yog 317L, los yog ntxiv ib tug corrosion inhibitor pob rau glycol, yog ib qho kev daws teeb meem zoo dua li tsuas yog nce lub thickness ntawm sheath.
Tshaj Thickness: Cov Txheej Txheem Tsim Cov Txheej Txheem Uas Txiav Txim Siab Kev Pabcuam Lub Neej
Phab ntsa thickness tsuas yog ib qho kev sib txawv hauv kev ua tiav ntev glycol rhaub lub neej. Qhov tseem ceeb tshaj plaws yog kev tswj cov pa oxygen. Lub tank loj kom zoo nrog ib daim pam nitrogen los yog lub diaphragm tshem tawm cov pa oxygen thiab txo tus nqi corrosion los ntawm qhov kev txiav txim ntawm qhov loj, tso cai rau kev siv cov phab ntsa thinner, thermally npaum. Qhov thib ob yam yog watt ntom. Specifying a longer heater or multiple heaters to reduce the surface watt density to 6 W/cm² or below keeps sheath temperatures under 140℃even with a 1.8 mm wall, dramatically slowing glycol oxidation. Qhov thib peb yam yog kua tshaj tawm. Cov cua kub cua sov yuav tsum tau muab tso rau hauv ib feem ntawm cov yeeb nkab uas qhov kev khiav ceev yog tsawg kawg yog 1.5-2.0 m / s kom ntseeg tau tias muaj cua sov hloov pauv thiab tiv thaiv kev kub ntxhov hauv zos lossis stagnation. Qhov thib plaub yog glycol zoo thiab kev saib xyuas. Siv inhibited glycol formulated rau cov kev pabcuam kub siab (nrog rau cov tshuaj tua kab mob thiab cov tshuaj antioxidants) ua kom lub neej ntawm cov kua dej thiab txo cov kua qaub. Kev ntsuas pH tsis tu ncua thiab khaws cia alkalinity, nrog rau kev hloov pauv kua dej thaum pH poob qis dua 6, tiv thaiv kev txhim kho ntawm cov kua qaub hnyav uas xav tau cov phab ntsa tuab.
Xaus: Kev Tshawb Fawb Txog Kev Tshawb Fawb Thickness rau Kev Pabcuam Glycol
Xaiv lub sheath thickness rau 316 stainless hlau ncig cua sov hauv 20% MEG ntawm 110℃thiab 4 bar yuav tsum tsis kam lees ob qho tib si. Cov phab ntsa nyias nyias hauv qab 1.0 hli yog qhov tsis tuaj yeem lees txais vim tias lawv tsis muaj cov khoom siv zoo rau cov xov sib txuas thiab muab kev tiv thaiv corrosion tsis txaus rau xyoo caum ntawm kev ua haujlwm. Cov phab ntsa tuab heev saum 2.0 hli yog qhov tsis zoo vim tias lawv nce qhov kub thiab txias rau hauv qhov chaw uas glycol oxidation accelerates, tsim cov kua qaub heev uas tawm tsam cov hlau. Qhov kev tshawb fawb pom tseeb yog 1.4-1.8 hli rau feem ntau cov ntawv thov kev lag luam, nrog tus nqi raug xaiv raws li cov tswv yim tswj cov pa oxygen thiab watt ntom. Rau cov txheej txheem nitrogen-pam nrog lub tank tsim tau zoo, 1.4-1.5 hli yog qhov zoo tshaj -nyias txaus kom lub plhaub kub qis dua 140℃ntawm 8 W / cm², tsis tau tuab txaus los muab 0.3-0.4 hli corrosion pub rau kaum xyoo. Rau lub kaw lus qhib uas ua pa ambient cua, 1.7-1.8 mm raug pom zoo, tab sis tsuas yog yog tias qhov ceev ntawm watt raug txo mus rau 6 W / cm² lossis qis dua. Thaum qhia meej, engineers yuav tsum tau hais txog qhov kev cia siab ntawm cov pa oxygen, qhov siab tshaj plaws ntawm cov ntaub qhwv qhov kub thiab qhov xav tau watt ceev. Qhov no txav cov kev sib tham los ntawm qhov yooj yim dimension mus rau ib tug ua tiav system engineering specification uas ncaj qha txuas phab ntsa thickness rau ob qho tib si corrosion kuj thiab thermal ua hauj lwm nyob rau hauv pressurized glycol cua sov loops.
