Lub Permeation -Driven Failure Mode hauv HF Microreactors
Nruam ntws microreactors tuav dilute hydrofluoric acid cov ntsiab lus, txawm nyob rau hauv ib txoj lw concentrations ntawm 0.1% mus rau 1.0% HF, impose ib tug tshwj xeeb tsis ua hauj lwm mechanism ntawm PFA-encapsulated heaters. Tsis zoo li cov tshuaj lom neeg ntau qhov chaw uas muaj kua qaub degrades lub polymer nto, kab HF permeates zoo PFA los ntawm molecular diffusion thiab condenses ntawm cov hlau core interface, pib pitting corrosion ntawm lub hauv paus alloy. Kev soj ntsuam ntau los ntawm 52 microreactor kev teeb tsa ua cov tshuaj thiab cov tshuaj lom neeg zoo qhia tau hais tias muaj kev sib raug zoo ntawm PFA phab ntsa thickness thiab lub sij hawm xav tau rau permeated HF kom khaws cov corrosive concentration ntawm cov hlau nto.
HF Permeation Kinetics Los ntawm PFA
Lub permeation ntawm hydrofluoric acid los ntawm fluoropolymer ua raws Fickian diffusion nrog ib tug muaj zog dependence rau molecular pawg. Tsis zoo li cov kua qaub loj dua uas nthuav tawm maj mam, HF cov molecules me txaus (molecular txoj kab uas hla 0.26 nm) mus rau hauv cov cheeb tsam amorphous ntawm PFA thaum tsim cov hydrogen nyob rau lub sijhawm - cov hlua khi uas ua rau kev thauj mus los. Kev ntsuas permeation raws li ASTM F739 ntawm 80℃qhia tias HF flux mus txog 1.0mm PFA yog 0.45 mg / cm²·hnub ntawm 0.5% HF concentration. Ob npaug phab ntsa thickness mus rau 2.0mm txo qhov flux mus rau 0.11 mg / cm²·hnub, qhov tseem ceeb ntawm plaub qhov txo qis tshaj qhov kev cia siab los ntawm Fick txoj cai vim tias cov concentration gradient tsav tsawg HF pawg los ntawm cov ntaub ntawv tuab. Ntawm 2.5 hli phab ntsa thickness, flux poob rau 0.05 mg / cm²·hnub.
Hlau Core Corrosion Threshold Concentration
Qhov tseem ceeb parameter rau cua sov ciaj sia tsis yog tag nrho HF permeated tab sis khov kho -lub xeev concentration ntawm HF ntawm hlau-polymer interface. Kev sim microreactor kev tshawb fawb siv Incoloy 825 cua sov cores qhia tias corrosion pib thaum interfacial HF concentration ntau tshaj 0.02% los ntawm qhov hnyav, sib npaug rau flux ntawm 0.08 mg / cm²·hnub khaws cia rau 500 teev. Hauv qab no qhov pib, cov txheej txheem passivation ntawm cov hlau tseem nyob ruaj khov. Lub sijhawm mus txog qhov pib yog nyob ntawm qhov ntim ntawm qhov sib txawv ntawm qhov sib txawv ntawm cov hlau thiab polymer, uas txawv nrog txoj kev tsim. Thaum tshav kub kub-shrink PFA liners tawm ntawm qhov sib txawv ntawm 0.01 txog 0.03mm uas muaj kwv yees li 0.3 mL ntawm cov cua nyob rau ib 'meter' ntawm lub rhaub ntev. Ntawm qhov HF flux ntawm 0.11 mg / cm²·hnub (2.0mm phab ntsa), qhov sib txuas ntawm lub ntsej muag nce mus txog 0.02% tom qab 220 teev. Ntawm 0.05 mg / cm²·hnub (2.5 hli phab ntsa), tib qhov pib yuav tsum tau 480 teev. Thaum corrosion pib, hlau pitting accelerates HF permeation los ntawm kev tsim ntse asperities uas nyob rau hauv lub zos kev nyuaj siab thiab nyias cov polymer los ntawm sab hauv.
Kub thiab Concentration Acceleration
Qhov tsawg kawg nkaus ruaj ntseg phab ntsa thickness nyob ntawm ob qho tib si HF concentration thiab kev khiav hauj lwm kub. Ntawm 70℃nrog 0.5% HF, 1.8mm PFA phab ntsa muab 0.10 mg / cm² · hnub flux, ncav cuag qhov pib corrosion ntawm 260 teev. Ntawm 50 degree, tib phab ntsa tuab txo qhov flux mus rau 0.04 mg / cm²·hnub, ncua sij hawm pib mus txog 650 teev. Rau microreactors ua 0.1% HF ntawm 60 degree, 1.5 hli phab ntsa yields flux ntawm 0.06 mg / cm²·hnub, nyob qis dua 0.08 mg / cm²· hnub pib tsis tas li vim khov kho- xeev interfacial concentration stabilizes qis dua 0.02%. Siab- ua haujlwm kub siab tshaj 90℃nrog txawm tias 0.2% HF yuav tsum muaj phab ntsa tuab tshaj 2.8mm kom flux qis dua 0.05 mg / cm²·hnub.
Yam tsawg kawg ntawm phab ntsa Thickness los ntawm kev ua haujlwm
| Kev Pabcuam Microreactor | Yam tsawg kawg nkaus PFA phab ntsa Thickness | Kev kwv yees HF Flux (mg / cm² · hnub) | Lub sij hawm rau 0.02% Interfacial HF (Corrosion Initiation) |
|---|---|---|---|
| 0.1% HF, 60 degree, nruam ntws | 1.5 hli | 0.06 | >1000 teev (hauv qab qhov pib) |
| 0.2% HF, 70 degree, sib tshuam | 1.8mm ib | 0.09 | 300 mus rau 350 teev |
| 0.5% HF, 70 degree, nruam | 2.2 hli | 0.07 | 500 txog 600 teev |
| 0.5% HF, 85 degree, nruam | 2.5 hli | 0.06 | 550-650 hnub |
| 1.0% HF, 70 degree, nruam | 2.5 hli | 0.10 | 260 mus rau 300 teev |
| 1.0% HF, 60 degree, nruam | 2.2 hli | 0.07 | 500-550 hnub |
Interface Design thiab Interfacial Volume txo
Phab ntsa thickness ib leeg tsis txiav txim siab HF-induced corrosion; lub interface ntim ntawm cov tub ntxhais hlau thiab PFA liner tseem ceeb hloov lub sijhawm rau qhov pib. Thaum tshav kub kub- cov ntaub qhwv me me ua kom muaj qhov sib txuas me me vim hais tias cov polymer cog lus rau cov hlau thaum lub caij txias, tawm hauv cov kab me me xwb. Dip -coated PFA liners, qhov twg cov kua polymer solidifies nyob ib ncig ntawm lub hauv paus, feem ntau muaj cov interface loj dua (0.05 mus rau 0.10mm qhov sib txawv) uas ntxiab cua ntau, yuav tsum tau ob mus rau peb zaug ntev dua rau HF kom ncav cuag corrosive concentration. Txawm li cas los xij, dip-coated liners kuj qhia tau tias muaj qhov tsis xws luag thaum pib. Rau kev pab cuam HF, qhia txog cov cua sov-shrink ntau dua li dip-coated siv nrog phab ntsa thickness xam los ntawm cov lus saum toj no ncua sij hawm rau corrosion pib los ntawm 40% mus rau 60% rau tej thickness muab.
Specification Guide rau Microreactor Heater Xaiv
Cov kws tsim qauv tsim cov microreactors tsis tu ncua rau HF- muaj cov kwj deg yuav tsum suav qhov xav tau PFA phab ntsa tuab siv qhov pib flux tus nqi ntawm 0.08 mg / cm²·hnub raws li qhov siab tshaj plaws permeation tus nqi rau 5000- teev kev pabcuam. Rau feem ntau daim ntawv thov nrog 0.2% mus rau 0.5% HF ntawm 60℃mus rau 70 degree, qhov kev xam no yuav tsum tau thickness ntawm 2.0mm thiab 2.3mm. Thaum yuav cov cua sov rau qhov kev pabcuam no, qhia cov cua sov- txo qis PFA kev tsim kho nrog cov ntawv pov thawj phab ntsa thickness ntsuas ntawm tsib lub ntsiab lus raws qhov ntev ntawm cov cua sov. Thov cov ntaub ntawv permeation flux los ntawm tus neeg muag khoom ntawm qhov tseeb HF concentration thiab kev khiav hauj lwm kub es tsis yog cov kab kos tshuaj lom neeg, raws li qhov pib tus cwj pwm yuav tsum muaj qhov tseem ceeb rau kev pab cuam lub neej kwv yees. Rau microreactors nrog lub siab sab hauv siab tshaj 50 psi, ntxiv 0.3mm rau cov thickness xam kom haum raws li qhov siab-driven permeation li.
