Cov pov thawj yog dab tsi-Raws li Sheath Thickness rau 316 Stainless Steel Heaters nyob rau hauv 5% Sodium Hypochlorite Solutions ntawm 40℃nrog Kev Sib Nqus Lub Luag Haujlwm?

Qhov Kev Lag Luam Tseem Ceeb - tawm hauv Chlorine Oxidising Service

Sodium hypochlorite (NaOCl) yog ib qho mob hnyav tshaj plaws rau cov hlau tsis muaj steel. Qhov no muaj zog oxidising biocide yog dav siv hauv kev kho dej, tshuaj dawb thiab huv. Nws cuam tshuam 316 stainless hlau los ntawm lub tshuab uas txawv ntawm chloride pitting. Hypochlorite ions tuaj yeem oxidise lub passive chromium oxide zaj duab xis ncaj qha mus rau soluble chromate hom, yog li tshem tawm cov txheej txheem tiv thaiv thiab nthuav tawm cov hlau hauv qab kom nrawm nrawm . 316 stainless steel undergoes ntsuas tsis zoo corrosion thiab ntau txaus ntshai pitting thiab kev nyuaj siab corrosion cracking ntawm concentrations tsawg li 5% thiab compromath kub ntawm 4 C. cov hlau txaus los tiv thaiv qhov kev xav tau ntawm qhov tob ntawm corrosion thiab qhov tseeb tias tsis muaj qhov ua tau tuab yuav ua rau lub neej ntev yog tias yuav tsum siv lub tshuab hluav taws xob cua sov hauv qhov kev npaj no, txawm tias tsuas yog nyob rau ib ntus. Qhov kev tshuaj ntsuam no ua rau cov ntaub ntawv pov thawj-raws li cov lus pom zoo rau thickness 316 stainless hlau hauv dilute hypochlorite cov kev pabcuam, raws li cov ntaub ntawv tshaj tawm corrosion thiab kev paub dhau los hauv kev kho dej hauv nroog thiab kev siv tshuaj ntxuav zaub mov.

Corrosion mechanisms thiab ntsuas qhov nkag mus rau hauv hypochlorite.

Cov lus teb corrosion ntawm 316 stainless hlau hauv sodium hypochlorite cov kev daws teeb meem nthuav tawm cov qauv kev kwv yees tau hais txog qhov concentration, kub, pH thiab lub sijhawm raug. % Laboratory immersion kev tshawb fawb ntawm 40℃ntawm NaOCl nrog pH hloov mus rau 9-10 (feem ntau rau cov tshuaj bleach lag luam) qhia txog cov corrosion tsis sib xws ntawm 0.3-0.8 mm / xyoo. Qhov siab kawg ntawm qhov ntau yog thaum cov tshuaj yog aerated los yog agitated, hloov cov hypochlorite concentration ntawm cov hlau nto. Yog li 1.2 hli phab ntsa yuav perforate nyob rau hauv 1.5-4 xyoo nyob rau hauv tas li immersion. Feem ntau cov kev siv ntawm hypochlorite cua sov yog, txawm li cas los xij, ntawm qhov xwm txheej tsis sib xws - lub tshuab cua sov ua haujlwm tsuas yog nyob rau hauv ib lub voj voog tshwj xeeb, thiab cov kev daws teeb meem yuav emptied, diluted los yog neutralized ntawm daim ntawv thov. Nrog rau lub sijhawm sib cuam tshuam ntawm cua sov rau ob teev hauv ib hnub, qhov zoo corrosion kuj yog 0.05 txog 0.15 hli hauv ib xyoos, muab lub neej theoretical ntawm 8 txog 24 xyoo rau phab ntsa 1.2 hli. Qhov kev txo qis no yog vim qhov kev tawm tsam corrosive xav tau ob qho tib si nquag hypochlorite thiab kub siab. Thaum lub sij hawm tawm cycles cov tshuaj txias thiab cov hypochlorite lov, ua rau tus nqi corrosion nyob ze nil. Qhov ntau pernicious tsis ua hauj lwm mechanism yog pitting nyob rau hauv hypochlorite. Txawm tias nyob rau ntawm 40℃qhov tseem ceeb pitting kub ntawm 316 stainless hlau nyob rau hauv 5% NaOCl yog tshaj thiab pits tuaj yeem pib hauv ob peb teev ntawm qhov raug. Thaum tsim ib lub qhov, qhov tob qhov tob nce ntawm tus nqi ntawm 0.5-1.5 hli / xyoo, ywj siab ntawm tus nqi tsis sib xws. Yog tias cov kev daws teeb meem zoo siab rau qhov pib, ib lub qhov dej tuaj yeem nkag mus rau phab ntsa 1.5 hli hauv 1-3 xyoos txawm tias muaj kev ua haujlwm tsis zoo. Cov ntaub ntawv pov thawj ntawm kev ua tsis tiav hauv lub tank hypochlorite 316 stainless hlau rhaub kom meej meej qhia tias cov txheej txheem perforation yog dominated los ntawm pitting es tsis sib xws thinning. Yog li ntawd, cov lus pom zoo thickness yuav tsum tau ua nyob rau hauv lub hauv paus ntawm qhov propagation tus nqi thiab tsis nyob rau hauv dav corrosion kam rau ua.

Thermal Limits thiab cov tswv yim cua sov Constraints

Kev daws teeb meem ntawm sodium hypochlorite yog qhov nyuaj rau cua sov vim tias hypochlorite yog thermally tsis ruaj khov, decomposing sai dua nrog nce kub. Nyob ze ntawm 40℃qhov kev tawg yog nruab nrab, tab sis nws yuav nrawm dua nyob ze ntawm lub plhaub, qhov twg qhov kub yuav ncav cuag 60-80℃rau kev daws teeb meem ntawm 40 degree. Corrosion yog tshwm sim los ntawm ob qho tib si oxygen thiab chloride ions (by-products ntawm hypochlorite tawg). Rau qhov muab lub zog tawm tswv yim, lub plhaub tuab ua rau qhov kub thiab txias dua, uas ua rau muaj kev tawm tswv yim zoo ntawm kev tawg sai dua thiab ntau dua chloride concentration ntawm cov hlau nto. Rau ib tug raug immersion rhaub nrog ib tug watt ceev ntawm 6-8 W / cm ^ 2 nyob rau hauv 40℃kua, ib tug 1.2 hli phab ntsa khaws ib tug sheath kub txog li 55-60 degree. Nrog rau phab ntsa thickness ntawm 2.0 hli qhov no nce mus rau 70-80 degree. Qhov kev puas tsuaj ntawm hypochlorite yog li peb zaug siab dua ntawm 70℃dua li ntawm 55 degree. Lub zos tsim cov tshuaj chloride ntxiv tuaj yeem txo cov peev txheej ntawm cov hlau tsis huv thiab yog li tuaj yeem txhawb nqa qhov pib ntxiv. Thermal modeling qhia tias lub sheath kub yuav tsum tau khaws cia hauv qab no 60℃kom tsis txhob ceev decomposition nyob rau hauv hypochlorite kev pab cuam. Qhov kev txwv no tau teeb tsa qhov siab tshaj plaws ntawm phab ntsa thickness. Rau ib lub raj ntawm 12 hli OD thiab 40℃hypochlorite, qhov siab tshaj plaws phab ntsa thickness yog li 1.6-1.8 hli kom cov sheath kub hauv qab 60℃ntawm ib tug watt ceev ntawm 5 W / cm2. Ntawm 8 W / cm2 phab ntsa tuab ntawm 1.2 hli tuaj yeem tshaj 60℃thiab yog li cov phab ntsa loj dua tsis xav tau tab sis thermally txwv.

Cov ntaub ntawv pov thawj-Raws li cov lus pom zoo Thickness rau ntau lub sijhawm ua haujlwm

Rau kev sib cuam tshuam hypochlorite cua sov, nyob rau hauv uas lub rhaub yog siv tsawg tshaj li 4 teev txhua hnub nrog ib lub lim tiam los yog dilute, lub thickness ntawm 1.2 mus rau 1.5 hli yuav txaus rau ib tug kev pab cuam lub neej ntawm 3 xyoo. Qhov nruab nrab corrosion pub rau 3 xyoos ntawm kev sib cuam tshuam (kwv yees 0.15-0.45 mm) tawm tsawg kawg 0.75 hli ntawm cov phab ntsa seem. Pitting kev pheej hmoo yog tswj los ntawm kev txwv qhov ntsuas kub ntawm lub tsho. 316 stainless hlau yog qhov kev xaiv tsis zoo rau txhua daim ntawv thov uas yuav tsum tau ua kom cua sov tsis tu ncua, xws li khaws cov tshuaj bleach cia ntawm 35-40 ° C los tiv thaiv crystallisation, tsis hais txog thickness. Qhov zoo sib xws ntawm corrosion yog 0.3-0.8 hli / xyoo nrog qhov raug tsis tu ncua, yog li 2.0 hli phab ntsa yuav kav tsuas yog 2.5-6.5 xyoo. Qhov tseem ceeb tshaj, cov pits tuaj yeem pib thiab nthuav nrog cov cua sov txuas ntxiv. Cov ntaub ntawv pov thawj los ntawm cov chaw kho dej khib nyiab hauv nroog uas tau sim siv 316 stainless hlau immersion rhaub hauv kev pabcuam hypochlorite txuas ntxiv, qhia tias qhov nruab nrab tsis ua haujlwm tom qab 12-24 lub hlis, txawm tias phab ntsa thicknesses ntawm 2.5-3.0 hli. Cov kev ua tsis tiav yog feem ntau pitting ntsig txog, tsis txawm hnav. Yog tias lub rhaub tau raug tshem tawm thiab ntxuav, qhov kev nyab xeeb tsim nyog yog phab ntsa tuab ntawm 1.5 mus rau 1.8 hli rau cov dej num sib cuam tshuam nrog kev ncua sij hawm. Lub thickness saum toj no 1.2 hli tsis yog feem ntau rau kev tiv thaiv corrosion tab sis rau cov neeg kho tshuab lub zog tiv thaiv kev puas tsuaj thaum lub sij hawm tshem tawm thiab reinstallation, uas yog ib txwm nyob rau hauv daim ntawv thov huv si.

Rau cov ntawv thov nrog lub voj voog luv luv, xws li cua sov cov tshuaj hypochlorite los ntawm 20℃mus rau 40℃ib zaug ib hnub rau kev ua haujlwm tshuaj tua kab mob, lub thickness ntawm 1.0 txog 1.2 hli yuav haum. Lub sij hawm raug luv luv minimizes tag nrho corrosion nkag mus thiab lub thermal efficiency ntawm ib tug nyias phab ntsa txo lub sij hawm ntawm cua sov, ntxiv txwv tsis pub raug. Tab sis txhua lub qhov dej uas pib hauv lub voj voog cua sov yuav loj hlob ntxiv thaum lub caij txias yog tias hypochlorite nyob rau hauv kov nrog cov hlau. Nws yog qhov pom zoo kom ntws cov tshuaj los yog nruab nrab tom qab txhua batch. Hauv txhua qhov xwm txheej, cov pov thawj txhawb nqa lub qab nthab 2.0 hli rau 316 stainless hlau hauv kev pabcuam hypochlorite. Saum toj no lub thickness ntawm lub thermal txim ua rau lub sheath kub rau hauv cheeb tsam ntawm sai hypochlorite decomposition, thiab cov hlau ntxiv tsis nce lub neej proportionally vim pitting, tsis uniform corrosion, tswj tsis ua hauj lwm.

Lwm cov khoom siv & tsim cov tswv yim uas ua tau zoo dua phab ntsa tuab

Thaum nws los txog rau hypochlorite cua sov, hloov cov ntaub ntawv sheath yog ze li ntawm ib txwm xaiv zoo dua li ntxiv thickness rau 316 stainless hlau. Titanium (Qib 2 lossis 7) yog cov qauv kev lag luam rau cov cua sov sodium hypochlorite daws. Nyob rau hauv hypochlorite titanium tsim ib tug ruaj passive zaj duab xis thiab yog resistant rau pitting mus txog rau concentrations ntawm 15% thiab kub ntawm 80 mus rau 90 degree. Lub titanium sheath 1.0-1.2 hli tuab yuav outlast ib 3.0 hli 316 stainless hlau sheath los ntawm ib tug ntau ntawm kaum los yog ntau tshaj. Tus nqi pib ntawm titanium sai sai ua rau hauv lub sij hawm luv luv thiab tsawg dua hloov. Thaum tsis muaj titanium, fluoropolymer txheej zoo li PTFE lossis PFA tuaj yeem muab tso rau ntawm 316 stainless hlau sheath. Cov txheej txheem no tiv thaiv cov hlau los ntawm cov tshuaj hypochlorite thiab tshem tawm tag nrho corrosion. Txawm li cas los xij, cov txheej txheem tuaj yeem ua rau puas tsuaj thiab yuav tsum tau saib xyuas. Lub tshuab cua sov coated (1.2 hli 316 stainless hlau core, 0.3-0.5 hli PTFE txheej) yog qhov zoo dua li 2.5 hli tsis kho 316 sheath. Thaum kawg, watt ceev yog txo mus rau 3-4 W / cm 2 los ntawm kev siv lub tshuab hluav taws xob ntev dua los yog ntau dua, ua kom lub tsho kub nyob rau hauv 5-10℃ntawm cov tshuaj ntau, thiab txo qis hypochlorite kev puas tsuaj thiab pitting txaus ntshai. Hauv kev siv tsis sib xws, 1.2 hli 316 sheath tuaj yeem ua rau lub neej txaus siab ntawm qhov tsawg watt ntom.

Xaus: Qhov hnyav ntawm cov pov thawj rau Hypochlorite Service Thickness

Thaum xaiv sheath thickness rau 316 stainless hlau rhaub nyob rau hauv 5% sodium hypochlorite ntawm 40 degree, ib tug yuav tsum paub hais tias cov khoom yog ua hauj lwm ntawm qhov txwv ntawm nws cov tshuaj tiv thaiv. Kev kuaj corrosion thiab kev ua tsis tiav hauv lub teb qhia tau hais tias pitting, tsis hnav tsis zoo, yog qhov tseem ceeb ntawm kev txiav txim siab lub neej kev pab cuam, thiab cov phab ntsa loj dua tuaj yeem txo qis dua li qhov tsawg kawg nkaus thickness ntawm 1.2-1.5 hli. Rau cov dej num sib cuam tshuam nrog tsawg tshaj li plaub teev cua sov ib hnub twg thiab kev tso dej tsis tu ncua lossis dilution qhov kev xaiv ntawm cov tuab yog pragmatic . 1.4-1.6 mm yog tuab txaus kom muaj sia nyob qee lub sijhawm rau ob mus rau peb lub xyoos, tab sis nyias txaus kom lub plhaub kub qis dua 60℃ntawm nruab nrab watt ntom ntom. Rau cov cua kub tsis tu ncua lossis txhua daim ntawv thov uas lub rhaub tsis tuaj yeem raug tshem tawm thiab tshuaj xyuas ib ntus, 316 stainless hlau tsis tuaj yeem siv tsis hais txog thickness thiab titanium lossis coated sheaths yuav tsum raug xaiv. Cov kev qhia tshwj xeeb rau kev pabcuam hypochlorite yuav tsum qhia qhov siab tshaj plaws watt ntom (4 W / cm 2 lossis tsawg dua), lub sijhawm ua cua sov txhua hnub thiab yog tias yuav tsum ua haujlwm txuas ntxiv rau titanium lossis coated lwm yam. Qhov no hloov qhov kev sib tham tsim tawm ntawm qhov kev yos hav zoov tsis muaj txiaj ntsig rau cov phab ntsa tuab 316 ntxiv rau cov khoom siv thiab cov kev daws teeb meem uas daws qhov teeb meem corrosion tiag tiag.