Ferric Sulfate Ib puag ncig
Ferric sulfate tov yog siv nyob rau hauv steel pickling, titanium dioxide pigment ntau lawm, thiab raws li etchants nyob rau hauv hlau xov. Cov tshuaj muaj ferric hlau nyob rau hauv concentration ntawm 50-200 g / L li Fe₂(SO₄)₃, nrog dawb sulfuric acid ntawm 20-100 g / L, ua hauj lwm ntawm 60-90 degree. Kev sib xyaw ua ke ntawm lub zog oxidizing muaj zog los ntawm ferric ion thiab acidity ntawm sulfuric acid ua rau muaj kev kub ntxhov rau ntau cov ntaub ntawv.
Impervious graphite-graphite impregnated nrog phenolic lossis furan resin tshem tawm cov porosity- yog dav siv rau cov khoom siv hluav taws xob hauv qhov kev pabcuam no. Graphite nws tus kheej resists sulfuric acid thiab ferric sulfate. Cov resin impregnant, txawm li cas los xij, tsis qhia qhov kev tiv thaiv no. Nyob rau lub sijhawm ntawm qhov kub siab, cov tshuaj ferric sulfate oxidizes cov resin, ua rau muaj kev puas tsuaj loj.
PTFE tsis muaj resin impregnant rau degrade. Tag nrho cov khoom yog chemically inert rau ferric sulfate thiab sulfuric acid. Kev sib piv ntawm impervious graphite thiab PTFE hauv qhov kev pabcuam no yog nruab nrab ntawm cov khoom siv sib xyaw uas nws cov ntaub ntawv qeeb qeeb thiab cov khoom sib xws uas tsis tuaj yeem ua rau cov kua dej sib xyaw.
Resin Degradation Mechanism
Impervious graphite yog tsim los ntawm impregnating ntxeem tau graphite nrog ib tug thermosetting resin -feem ntau phenolic los yog furan - nyob rau hauv lub tshuab nqus tsev thiab siab. Cov resin sau cov pores sib cuam tshuam, ua rau cov khoom tsis tuaj yeem ua cov kua dej. Lub graphite muab thermal conductivity thiab tshuaj tiv thaiv. Cov resin muab impermeability.
Ferric sulfate tawm tsam cov resin los ntawm oxidation. Lub ferric ion (Fe³⁺) yog ib qho muaj zog oxidizer. Nws abstracts hydrogen los ntawm cov resin polymer, tsim cov dawb radicals uas hnov mob nrog yaj oxygen los ua carbonyl thiab carboxyl pawg. Cov oxidized resin ua nkig. Micro- cracks tsim. Cov kab nrib pleb nthuav tawm cov resin tshiab rau qhov kev daws, perpetuating qhov kev tawm tsam.
Raws li cov resin degrades, ntau hom kev ua tsis tiav. Cov resin-graphite daim ntawv cog lus tsis muaj zog, thiab cov khoom graphite tuaj yeem tso rau hauv cov txheej txheem kwj. Kev poob ntawm cov resin los ntawm qhov chaw tsim cov porosity saum npoo, ua rau qhov tseeb ntawm qhov chaw thiab ua kom nrawm nrawm dua. Nws thiaj li, interconnected porosity tsim los ntawm lub raj phab ntsa, thiab cov txheej txheem kua ntws los ntawm lub tshav kub exchanger phab ntsa.
| Degradation Parameter | Phenolic Resin (Impervious Graphite) | Impervious Graphite (Furan Resin) | PTFE |
|---|---|---|---|
| Binder / cov khoom siv | Phenolic resin nyob rau hauv graphite matrix | Furan resin nyob rau hauv graphite matrix | Homogeneous fluoropolymer |
| Binder oxidation tsis kam | Poob (tawm los ntawm Fe³⁺) | Nruab nrab (zoo dua phenolic) | N / A (tsis muaj binder) |
| Resin degradation tus nqi ntawm 80℃hauv Fe₂(SO₄)₃ | 0.1-0.3 hli / xyoo (sov deg) | 0.05-0.15 hli / xyoo | 0 |
| Graphite particle tso tawm | Yog (raws li resin degrades) | Yog (txo tus nqi) | Tsis muaj |
| Deg mob tom qab 2 xyoos | Porous, roughened | Nruab nrab roughened | du, tsis hloov |
| Permeability tom qab 3-5 xyoos | Tej zaum yuav txhim kho los ntawm - phab ntsa ntub dej | Tej zaum yuav txhim kho los ntawm - phab ntsa ntub dej | Tsis yog (zero permeability) |
| Kev pabcuam lub neej hauv Fe₂(SO₄)₃ ntawm 80℃(xyoo) | 3-6 | 5-8 | 15+ |
Kev Tshaj Tawm -Composite Degradation Feedback
Cov resin degradation tsim nto porosity. Qhov ntxeem tau qhov chaw yog mechanically tsis muaj zog dua li qub resin-impregnated nto. Nyob rau hauv ntws ferric sulfate tov, cov ntxeem tau nto erodes sai tshaj li ib tug du, impermeable nto yuav. Erosion tshem tawm cov degraded resin thiab ib nrab detached graphite hais, nthuav tawm cov khoom tshiab rau tshuaj tua kab mob.
Qhov kev tawm tswv yim no - tshuaj tua kab mob tsim porosity, porosity accelerating erosion, yaig exposing deg tshiab - txhais tau hais tias degradation tus nqi ntawm impervious graphite yog sai dua li cov tshuaj oxidation tus nqi ib leeg yuav kwv yees. Kev sib xyaw ua ke chemo-mechanical degradation txiav txim siab lub neej ua haujlwm tiag tiag.
PTFE tsis muaj cov lus qhia zoo li no. Lub homogeneous polymer nto erodes maj mam thiab uniformly nyob rau hauv ntws, tsis muaj tshuaj pab rau cov khoom poob. Tus nqi yaig tsuas yog txiav txim siab los ntawm cov kua dej tshaj tawm thiab cov abrasiveness ntawm cov khoom raug tshem tawm - cov yam ntxwv uas cuam tshuam rau ob qho khoom siv tab sis yog sib xyaw los ntawm tshuaj tua kab mob hauv graphite nkaus xwb.
Cov ntsiab lus
PTFE heat exchangers outperform impervious graphite nyob rau hauv kub ferric sulfate daws vim PTFE yog ib homogeneous khoom uas tsis muaj resin binder rau oxidize. Impervious graphite cia siab rau phenolic los yog furan resin impregnant uas tau tawm tsam los ntawm oxidizing ferric ion, tsim cov porosity saum npoo uas ua rau yaig thiab thaum kawg ua rau los ntawm - phab ntsa to. PTFE muab ib tug du, chemically inert nto uas degrades tsuas yog los ntawm qeeb mechanical yaig, xa 15+ xyoo kev pab cuam lub neej piv rau 3-8 xyoo rau impervious graphite.
Kev txhawb nqa engineering rau PTFE heat exchanger specification nyob rau hauv ferric sulfate thiab lwm yam kev siv tshuaj oxidizing yog muaj thaum xa cov tshuaj muaj pes tsawg leeg, qhov kub thiab txias, ntws tshaj tawm, thiab cov ntaub ntawv siv cov khoom siv tam sim no.
