Thaum Tshav Kub Kub Kub Siv Titanium Reheat Dilute Caustic Soda ntawm 90 degree, Yuav Ua Li Cas Cov Txheej Txheem Sodium Titanate cuam tshuam rau cov cua kub hloov dua 1000 teev?
Tso lus
Dilute caustic soda (sodium hydroxide, NaOH) cov kev daws teeb meem ntawm qhov siab ntawm 5-15% thiab qhov kub ntawm 90℃feem ntau yog siv los ntxuav-hauv- qhov chaw (CIP) systems, kev kho hlau, thiab kev ua tshuaj. Titanium nthuav tawm zoo heev corrosion kuj nyob rau hauv cov kev daws teeb meem txog li 120 degree, nrog rau cov corrosion tsis zoo hauv qab 0.05 hli ib xyoo. Txawm li cas los xij, qhov sib txawv degradation mechanism cuam tshuam rau kev ua haujlwm ntawm lub tshuab cua sov: qhov tsim ntawm sodium titanate nplai. Sodium titanate (Na₂Ti₆O₁₃ lossis zoo sib xws stoichiometries) precipitates ncaj qha mus rau lub titanium raj nto los ntawm cov tshuaj tiv thaiv ntawm NaOH thiab cov titanium oxide passive zaj duab xis los yog lub hauv paus hlau nws tus kheej. Qhov ntsuas no yog ceramic-zoo li, nrog thermal conductivity tsawg heev (kwv yees li 2–3 W / m·K piv rau 21.9 W / m·K rau titanium). Nyob rau tib lub sijhawm, cov nplais accumulating ua raws li cov txheej txheem insulating, txo cov cua sov ua haujlwm, ua kom lub cev kub ntawm daim tawv nqaij, thiab ua rau muaj kev kub ntxhov thiab tsis ua haujlwm.
Mechanism ntawm Sodium Titanate Scale Formation
Hauv cov kev daws teeb meem kub kub, titanium dioxide passive zaj duab xis yog thermodynamically tsis ruaj khov. Cov tshuaj tiv thaiv tshwm sim: 6TiO₂ + 2NaOH → Na₂Ti₆O₁₃ + H₂O. Cov tshuaj tiv thaiv no tshwm sim tsis tu ncua ntawm titanium- daws teeb meem interface. Cov sodium titanate crystals nucleate ncaj qha rau ntawm lub raj nto thiab loj hlob sab nraud rau hauv cov tshuaj caustic. Tsis zoo li cov hlau oxide nplais uas tej zaum yuav spilled los yog nyob twj ywm nyias, sodium titanate tseem loj hlob ntev li ntev raws li titanium raug rau kub NaOH. Qhov ntsuas qhov loj hlob yog qhov kub thiab txias -nyob thiab concentration{10}}nyob ntawm. Ntawm 90℃thiab 10% NaOH, qhov ntsuas loj hlob kwv yees li 5-10 µm hauv ib lub lis piam pib, qeeb mus rau 1-2 µm ib lub lis piam tom qab ob peb puas teev raws li qhov sib txawv ntawm cov teeb meem thickens. Cov nplai yog adherent thiab nyuaj rau tshem tawm cov neeg kho tshuab lossis tshuaj tsis muaj kev puas tsuaj rau titanium puag hlau.
Kev txo qis hauv kev hloov hluav taws xob ntau dua 1000 teev
Kev ntsuas ntsuas hauv 10% NaOH ntawm 90℃nrog qhov kub tsis tu ncua ntawm 15 W / cm² tau tsim cov kev loj hlob hauv qab no thiab kev hloov pauv cua sov rau Qib 2 titanium:
0-100 teev (thaum pib): Scale thickness ntawm 5-15 µm. Thaum tshav kub kub hloov coefficient txo 5-10%. Tube saum npoo kub nce ntawm 3-5℃saum toj no huv si. Yam tsawg kawg nkaus kev ua haujlwm.
100-300 teev (lub sijhawm hloov pauv): Scale thickness ntawm 20-40 µm. Thaum tshav kub kub hloov coefficient txo 15-25%. Tube saum npoo kub nce ntawm 8-12 degree. Rhaub Cycling zaus nce los tswj cov txheej txheem kub.
300-600 teev (lub sijhawm ua ke): Scale thickness ntawm 50-80 µm. Thaum tshav kub kub hloov coefficient txo 30-45%. Tube saum npoo kub nce ntawm 15-20 degree. Kev siv hluav taws xob nce 20-30% kom xa tib lub cua sov rau caustic.
600-1000 xuab moos (mature scale): Scale thickness ntawm 90-120 µm. Thaum tshav kub kub hloov coefficient txo 50-60%. Tube saum npoo kub nce ntawm 25-35 degree. Kev overheating hauv zos tuaj yeem ua rau kub hnyiab ntawm lub raj nplaim, ua kom cov nplai loj hlob ntxiv.
Scale Management thiab Phab Ntsa Thickness Selection Guide
Cov lus hauv qab no muab lub hauv paus kev txiav txim siab rau kev tswj xyuas sodium titanate scale raws li caustic concentration, kev khiav hauj lwm kub, thiab xav tau kev pab cuam lub sij hawm:
| Caustic Condition & Service Requirement | Pom zoo Initial Phab Ntsa Thickness (mm) | Cia siab Scale Thickness ntawm 1000 Teev | Mitigation Strategy & Trade-Tawm |
|---|---|---|---|
| 5% NaOH, 80 degree, ua haujlwm tsis sib xws (<200 hours/year) | 1.2 hli | 30–40 µm | Tsis tas yuav tshem tawm nplai. Cua sov lub neej txiav txim los ntawm corrosion, tsis scaling. |
| 10% NaOH, 90 degree, ua haujlwm tsis tu ncua (8000 teev / xyoo) | 1.5 hli | 80–100 µm | Kev tu txhua xyoo (nylon txhuam, tsis muaj hlau) lossis tshuaj ntxuav (5% citric acid, 60 degree, 2 teev). Txais 20% qhov nruab nrab kub hloov pauv poob. |
| 15% NaOH, 100 degree, 24/7 kev ua haujlwm, kev ua haujlwm siab xav tau | 2.0mm ib | 120–150 µm | Nruab ob lub tshuab cua sov ua ke, ntxuav ib qho thaum lwm tus ua haujlwm. Qhia kom meej qis watt ceev (10 W / cm²) kom txo qis kev loj hlob tus nqi. |
| Retrofit of existing heater with >50% tshav kub hloov pauv | Tsis siv tau | Yuav tsum tau ntxuav | Tshuaj ntxuav: ncig 5% HCl lossis 10% citric acid ntawm 60℃rau 4-6 teev. Yaug kom huv si ua ntej rov qab mus rau kev pabcuam caustic. |
| Scale- tiv taus tsim, lub sijhawm ua haujlwm siab tshaj plaws | 1.5 hli nrog electropolished nto (Ra<0.2 µm) | 40-50 µm (50% txo) | Smooth nto muab tsawg dua qhov chaw nucleation. Electropolishing tus nqi them nqi ntawm 15–20% tshaj li -draw tube. |
Engineering Beyond Scale Formation Control
Cov qib titanium alloy tseem cuam tshuam rau sodium titanate nplai kev loj hlob. Qib 7 (palladium-stabilized) qhia tau hais tias kwv yees li 30% qis dua qhov kev loj hlob ntawm qib 2 vim yog palladium's catalytic nyhuv ntawm cov zaj duab xis passive stability. Qib 12 (molybdenum-}nickel) qhia txog kev loj hlob zoo sib xws rau Qib 2. Phab ntsa tuab muab cov npoo kev nyab xeeb rau corrosion hauv qab qhov teev; sodium titanate nplai tsis tiv thaiv kev siv titanium txuas ntxiv, uas tau nce ntawm 0.02-0.05 hli hauv ib xyoos hauv qab qhov ntsuas. Cov nplai kuj ua rau muaj kev cuam tshuam rau thermal cycling puas tsuaj; Qhov sib txawv ntawm thermal expansion ntawm titanium (8.6 × 10⁻⁶ / degree) thiab sodium titanate (kwv yees li 10–12 × 10⁻⁶ / degree) ua rau muaj kev ntxhov siab thaum kaw, uas tuaj yeem nthuav tawm cov titanium tshiab kom nrawm nrawm thaum rov pib dua.
Ua ib qho kev qhia tshwj xeeb
Thaum qhia txog lub tshuab cua sov titanium rau dilute caustic soda reheating ntawm 90 degree, suav nrog cov phiaj xwm kev tswj hwm hauv cov txheej txheem ua haujlwm. Thov los ntawm tus neeg muag khoom ib qho electropolished nto tiav kom txo cov nplai nucleation qhov chaw. Rau kev pabcuam txuas ntxiv tshaj li 3,000 teev hauv ib xyoos, qhia Qib 7 titanium thiab tsim lub tshuab rhaub nrog 20% ntau dua ntawm thaj chaw kom them rau qhov ntsuas - vim tias qhov kub hloov pauv. Nruab ib lub ntsuas kub ntawm lub raj nplaim los yog ntsuas qhov kub thiab txias ntawm lub caustic hla lub rhaub; 15% txo qis hauv ΔT ntawm lub zog tas li qhia tau hais tias qhov loj me ntawm qhov yuav tsum tau ntxuav. Rau tshuaj ntxuav, tsis txhob siv hydrochloric acid siab tshaj 10% concentration lossis ntawm qhov kub siab tshaj 60 degree, vim qhov no tuaj yeem ua rau hydrogen embrittlement ntawm titanium. Hloov chaw, siv citric acid lossis EDTA-cov tshuaj ntxuav raws li tsim tshwj xeeb rau cov khoom siv titanium. Los ntawm kev cia siab tias sodium titanate scale tsim ua ib qho tseem ceeb ntawm kev ua haujlwm ntau dua li qhov tsis ua haujlwm corrosion, tus kws ua haujlwm ua kom muaj cua sov ua haujlwm zoo ib yam thiab kev saib xyuas lub sijhawm nyob rau hauv cov kev pabcuam kub kub.
