Lub khw muag khoom hlau tau rub lub PTFE immersion rhaub los ntawm alkaline tu tank tom qab tsib lub hlis ntawm kev pabcuam. Lub sheath nto tau them nrog ib qho nyuaj, iav zaj duab xis uas tiv thaiv kev tshem tawm los ntawm dilute acid. The maintenance team had to use a chisel to break the film away, which gouged the PTFE in several places. Cov yeeb yaj kiab tsis yog qhov zoo tib yam calcium carbonate nplai. Nws yog ib lub iav silicate uas tau fused rau ntawm lub tshuab cua sov.
Silicate iav films yog cov feem ntau tenacious deposits pom ntawm PTFE immersion heaters. Lawv tsim nyob rau hauv alkaline ntxuav da dej uas muaj sodium silicate, ib tug ntau additive siv rau buffering, corrosion inhibition, thiab av ncua kev kawm ntawv. Cov silicate polymerizes rau ntawm qhov chaw kub los ua ib lub khob-zoo li txheej uas khi rau PTFE.
Vim li cas Silicate Films Form on Hot Surfaces
Sodium silicate yog sib xyaw ntawm sodium oxide thiab silicon dioxide. Hauv kev daws, nws tshwm sim li silicate ions. Thaum cov tshuaj tiv tauj ib qho chaw kub, cov silicate polymerizes - silicate ions txuas ua ke los tsim cov saw ntev thiab cov tes hauj lwm. Lub polymerization yog tsav los ntawm qhov kub thiab txias los ntawm evaporation ntawm cov dej ntawm qhov chaw kub.
Cov polymerized silicate ua ib zaj duab xis uas nyuaj, tshuaj tiv thaiv, thiab nruj nreem khi rau saum npoo. Cov zaj duab xis loj hlob raws li ntau silicate deposits. Nws ua tuab dua thiab ntau dua iav-zoo li dhau sijhawm. Tsis zoo li carbonate scale, uas adheres los ntawm mechanical interlocking, silicate films bond chemically rau PTFE nto.
| Silicate Concentration | Da dej kub | Sheath Surface Temperature | Zaj duab xis tsim tus nqi | Lub sij hawm mus rau 1 mm Zaj duab xis |
|---|---|---|---|---|
| 1–2% | 60 degree | 75 degree | Tsawg | 6–12 lub hlis |
| 2–4% | 70 degree | 85 degree | Nruab nrab | 3–6 lub hlis |
| 4–6% | 75 degree | 95 degree | Siab | 6-12 lub lis piam |
| >6% | 80 degree | 105℃+ | Siab heev | 3-6 lub lis piam |
Silicate zaj duab xis tsim tus nqi raws li kev ua haujlwm ntawm cov concentration thiab sheath kub
Yog vim li cas Silicate Films muaj kev puas tsuaj ntau dua li Carbonate Scale
Carbonate nplai yog qhov muag thiab ntxeem tau. Nws adheres los ntawm mechanical interlocking thiab qaug zog van der Waals rog. Dilute acid dissolves nws, thiab PTFE nto hauv qab no feem ntau zoo lawm.
Silicate films txawv. Lawv yog cov tawv, ntom, thiab chemically bonded rau PTFE. Lub silicate network tsim covalent bonds nrog lub polymer nto. Zaj duab xis tsis yaj nyob rau hauv acid. Nws yuav tsum tau alkaline tu los yog mechanical tshem tawm.
Kev tshem tawm cov tshuab-scraping, chiseling, lossis abrasive blasting-ua rau PTFE puas thiab tsim cov chaw nucleation rau kev tsim cov yeeb yaj kiab yav tom ntej. Cov cheeb tsam puas tau txais ntau dua rau silicate sib txuas dua li qhov qub du nto.
Lub luag haujlwm ntawm Sheath Surface Temperature
Silicate polymerization tus nqi nce nrog kub. Txhua 10℃nce roughly doubles tus nqi. Lub tshuab cua sov ua haujlwm ntawm 95℃qhov kub ntawm cov ntaub ntawv silicate zaj duab xis ob zaug sai li ib qho ntawm 85 degree.
Qhov kub ntawm qhov chaw nyob ntawm qhov watt ceev thiab cov dej ntws. Lub rhaub ua haujlwm ntawm 1.4 W / cm² hauv chav da dej me me tuaj yeem muaj qhov kub ntawm 15-20℃saum toj no. Lub tshuab cua sov ntawm 0.9 W / cm² yuav muaj qhov kub thiab txias tsuas yog 10-12℃saum toj no. Qhov qis watt ceev txo qhov kub ntawm qhov chaw thiab ua rau cov yeeb yaj kiab qeeb.
Tiv thaiv silicate zaj duab xis tsim
Qhov kev tiv thaiv zoo tshaj plaws yog kom txo qis qhov kub ntawm lub plhaub. Qhov qis watt ntom ntom ua kom lub ntsej muag txias dua thiab ua kom cov polymerization qeeb. Lub tshuab cua sov ua haujlwm ntawm 0.9 W / cm² yuav siv sijhawm ntev li ob zaug los ua ib zaj duab xis 1 hli raws li ib qho ntawm 1.4 W / cm².
Ib tug polished nto txo cov adhesion zog ntawm silicate zaj duab xis. Ib tug du nto muab tsawg dua nucleation qhov chaw thiab tsawg mechanical interlocking. Polished nto ncua lub sij hawm tu los ntawm 30-50% piv rau cov qauv nto.
Kev tu tsis tu ncua tshem tawm cov zaj duab xis ua ntej nws ua tuab thiab tenacious. Ib zaj duab xis nyias yog yooj yim tshem tawm dua li cov tuab tuab. Lub sijhawm tu yuav tsum yog raws li kev soj ntsuam tshawb pom, tsis yog daim ntawv teev sijhawm tas.
| Kev Tiv Thaiv Kev Ntsuas | Qhov cuam tshuam rau zaj duab xis tsim | Kev nqis tes ua |
|---|---|---|
| Tsawg watt ceev, 0.9 W / cm² | Tsawg polymerization | Cua sov tsim |
| Polished nto | Txo adhesion | Heater tiav |
| Kev tu tsis tu ncua | Tiv thaiv zaj duab xis tuab | Lub sijhawm tu |
| Txo cov silicate concentration | Tsawg deposition tus nqi | Da dej chemistry tswj |
Kev tiv thaiv kev ntsuas rau silicate zaj duab xis tsim hauv alkaline ntxuav
Ntxuav silicate zaj duab xis yam tsis muaj kev puas tsuaj rau lub rhaub
Silicate films tsis yaj nyob rau hauv acid. Lawv yuav tsum tau alkaline tu los yog mechanical tshem tawm.
Cov tshuaj ntxuav alkaline- feem ntau 5-10% sodium hydroxide ntawm 50-60℃- tuaj yeem ua rau cov yeeb yaj kiab silicate soften thiab tso cai rau nws txhuam tawm. Cov tshuaj ntxuav tu yuav tsum tau nthuav tawm los yog agitated kom muaj kev sib cuag nrog zaj duab xis. Lub tshuab cua sov yuav tsum tau kuaj xyuas tom qab ntxuav kom paub meej tias cov yeeb yaj kiab tau raug tshem tawm.
Kev tshem tawm tshuab yuav tsum yog qhov kawg. Yog tias tsim nyog tshem tawm cov tshuab, siv cov yas scraper lossis txhuam txhuam. Tsis txhob siv cov txhuam hlau, hlau txhuam, lossis cov ntaub qhwv ntsej muag, uas yuav ua rau PTFE puas.
Thaum Silicate Film qhia txog qhov teeb meem tshwj xeeb
Lub tshuab cua sov uas tsim cov yeeb yaj kiab tuab silicate txawm tias tu tsis tu ncua qhia tau hais tias lub rhaub dej ua haujlwm ntawm watt ceev uas siab dhau rau cov tshuaj da dej. Ib qho kev cai PTFE immersion rhaub configuration nrog qis watt ceev, polished nto, thiab ib tug loj deg cheeb tsam nyob rau hauv lub hauv paus ntawm silicate deposition. Cov txheej txheem tshwj xeeb yuav tsum muaj cov tshuaj da dej, cov silicate concentration, kev ua haujlwm kub, thiab qhov xav tau wattage. Rau cov chaw uas muaj silicate- muaj cov tshuaj ntxuav alkaline, daim ntawv thov no- tshwj xeeb txoj hauv kev txo qis kev tsim cov yeeb yaj kiab thiab txuas ntxiv lub neej ntawm cov cua sov.
