Ntawm Dab tsi tshwj xeeb kev sib xyaw ntawm Nitric Acid Concentration thiab Kub Puas Yog 1.6 millimeter 316 Stainless Steel Sheath Yuav Tsum Tau Derating Hauv qab 12 Watts Ib Square Centimeter los tiv thaiv Intergranular Attack hauv Pharmaceutical Reactor Service?

Cov txheej txheem engineers tsim hluav taws xob tso cua sov rau cov tshuaj reactors thiab tshuaj synthesis cov hlab ntsha feem ntau siv nitric acid rau passivation, tu thiab ua cov tshuaj tiv thaiv nruab nrab. Feem ntau cov ntsiab lus yog 10-30% nitric acid ntawm 40-70 ° C. 316 stainless hlau sheath . Lub 1.6 hli sheath feem ntau yog siv rau hauv kev pab cuam kws tshuaj vim hais tias ntawm cleanability yuav tsum thiab corrosion kuj. Txawm li cas los xij, thaum welded flanges los yog cov khoom txuas tau siv, thaj chaw muaj kev kub ntxhov tuaj yeem ua rau muaj kev cuam tshuam rau kev sib tsoo ntawm qee qhov kev sib xyaw ua ke. Daim ntawv qhia txog qhov tsawg kawg nkaus qhov tseem ceeb, hauv qab no uas 1.6 hli 316 sheath yuav tsum tau derated nyob rau hauv watt ceev kom tsawg tshaj li 12 W / cm² los tiv thaiv intergranular nres nyob rau hauv kws tshuaj reactor kev pab cuam.

Mechanism ntawm Nitric Acid Intergranular Attack
Rau 316 nyob rau hauv nitric acid, intergranular nres yog tshwm sim los ntawm chromium carbides precipitating ntawm weld grain ciam teb thiab depleting nyob ze thaj tsam ntawm chromium nyob rau hauv tshav kub - cuam tshuam cheeb tsam. Nitric acid feem ntau tawm tsam cov chromium depleted zones uas ua rau grain ciam corrosion uas yuav ua rau flange dislocation los yog sheath to. Concentration thiab kub dependence ntawm rhiab heev rau intergranular quab yuam. Tawm tsam hauv 10% nitric acid tsuas yog pom zoo ntawm 80 ° C. Hauv 20% nitric acid qhov pib yog 65 ° C. Tawm tsam hauv 30% nitric acid ntawm qhov kub siab tshaj 55^0C. Hauv 40% nitric acid, kev tawm tsam tshwm sim saum 45 degree. Qhov cuam tshuam tshaj plaws ntawm 1.6 hli sheath nrog welded flange yog lub tshav kub - cuam tshuam cheeb tsam. Vim tias watt ntom ntom, qhov kub ntawm lub plhaub feem ntau yog 10-20℃siab dua qhov kub ntawm cov kua qaub. Lub plhaub saum npoo attains 73℃ntawm qhov kub ntawm 55℃hauv 30% nitric acid nrog lub rhaub ntawm 12 W / cm2 (18℃nce) zoo tshaj qhov pib rau intergranular nres ntawm 55 degree.

Qhov tseem ceeb Derating Thresholds rau 1.6mm Sheath
Thaum immersion kuaj nyob rau hauv nitric acid ntawm qhov kub thiab txias muaj feem xyuam rau cov kev pab cuam kws, cov nram qab no watt ceev txwv rau ib tug 1.6 hli phab ntsa sheath muaj feem xyuam rau tiv thaiv intergranular nres nyob rau hauv lub tshav kub cuam tshuam cheeb tsam ntawm welded 316 qauv:

Nitric Acid Concentration Bulk Acid Temperature Maximum Sheath Surface Temperature for No Intergranular Attack Maximum Allowable Watt Density for 1.6 mm Sheath (15℃sawv ntawm 10 W / cm2) Cia Siab Lub Sijhawm Tawm Tsam ntawm Higher Watt Density 10% 50℃80℃2 10% Kev nyab xeeb ntawm watt / watt 60℃80℃13 W/cm2 Safe ntawm 12 W/cm2 10% 70℃80℃7 W/cm2 Derating tsim nyog hauv qab no 12 W/cm² 10% 75°C 80°C 3 W/cm² 316 marginal; 316L nyiam 20% 40 ° C 65 ° C 17 W / cm² Safe ntawm 12 W / cm² 20% 50 ° C 65 ° C 10 W / cm² Derating pom zoo < 12 W / cm² 20% 55 ° C 65 ° C 7 W / cm² Derating xav tau
20% 60 ° C 65 ° C 3 W / cm² Siv 316L los yog annealed 30% 35 ° C 55 ° C 13 W / cm² Safe ntawm 12 W / cm² 30% 40 ° C 55 ° C 10 W / cm² Derating pom zoo 30% 45 ° C 7 5 cm²
30% 50℃55℃3 W / cm² Siv 316L lossis upgrade alloy
40% 30 ° C 45 ° C 10 W / cm² Derating pom zoo 40% 35 ° C 45 ° C 7 W / cm² Derating yuav tsum
40% 40 ° C 45 ° C 3 W / cm² 316 tsis pom zoo
Nyob rau hauv ib tug kws reactor, lub sheath nto kub ntawm ib tug 1.6 hli sheath ntawm 12 W / cm2 tshaj qhov pib ntawm 65℃mus rau ze li ntawm 70 degree, rau 20% nitric acid ntawm 55℃tej kub. Inter-kev ua phem phem tuaj yeem tshwm sim hauv 6-12 lub hlis. Derating mus rau 8 W / cm² (13 ° C nce, 68 ° C nto) tseem overshoots cov txheej txheem . 4 W / cm² (6 ° C nce, 61 ° C nto) derating tuav lub sheath hauv qab 65 ° C, tsis txhob ua phem.

Lub hnab ntawv ua haujlwm nyab xeeb rau 12 W / cm² Kev Ua Haujlwm
Cov lus hauv qab no qhia txog qhov kub siab tshaj plaws ntawm nitric acid rau 1.6 hli 316 sheath ntawm 12 W / cm² (18 ° C nce) txhawm rau tiv thaiv kev cuam tshuam ntawm kev sib tsoo hauv qhov vuam cua sov- thaj tsam cuam tshuam.

Nitric Acid Concentration Maximum Safe Bulk Temperature at 12 W/cm² (18°C rise) Sheath Surface Temperature at Maximum Safe Bulk Required Above Maximum 10% 62°C 80°C Derating below 12 W/cm² 15% 52°C 70°C Derating yuav tsum tau Derating 25% 42 ° C 60 ° C Siv 316L los yog derate 30% 37 ° C 55 ° C 316L yuav tsum tau 35% 32 ° C 50 ° C Txhim kho alloy pom zoo 40% 27 ° C 45 ° C 316 tsis haum
Rau cov tshuaj reactor nrog 20% ​​nitric acid ntawm 50 ° C bulk kub nrog 12 W / cm² qhov kev nyab xeeb bulk txwv yog 47 ° C. Lub tshuab cua sov muaj kev nyab xeeb txog li 50℃C. Muaj qhov txaus ntshai ntawm intergranular nres. Pom zoo kom qis watt ceev mus rau 8 W / cm² (13 ° nce, 63 ° nto) los yog qhia cov khoom qib 316L.

Tsim kev hloov kho kom tsis txhob muaj kev tawm tsam Intergranular
Rau cov txheej txheem tshuaj uas xav tau nitric acid ntau thiab qhov kub thiab txias ze rau qhov chaw nres tsheb, peb qhov kev hloov kho tuaj yeem tiv thaiv kev tawm tsam intergranular yam tsis muaj derating hauv qab 12 W / cm². Thawj yog xaiv 316L (tsawg carbon, max .03%) es tsis txhob siv cov pa 316. Cov pa roj carbon tsawg tsawg txo cov nag lossis daus ntawm chromium carbide thaum lub vuam thiab ua kom qhov chaw nres los ntawm 10–15 ° C. 316L ntawm 12 W / cm² hauv 20% nitric acid bulk 60 ° C. Qhov kev txhim kho thib ob yog kev tshaj tawm -weld annealing ntawm thaj chaw flange txuas. Localized induction anneal mus rau 1050 ° C tshem tawm cov chromium carbides thiab rov ua kom corrosion kuj. Qhov kev hloov pauv zaum kawg yog siv cov weld overlay lossis clad flange uas 316 sheath yog welded rau qhov tsim nyog tab sis tsis tshua muaj kev nkag siab ntau dua - cov hlau alloy. Rau cov kws tshuaj reactors xav tau 30% nitric acid ntawm 50 ° C nrog kev ua haujlwm tas mus li, cov kws ua haujlwm yuav tsum tau hloov mus rau lub siab silicon stainless hlau xws li Durimet 20 lossis Alloy 825. Cov ntaub ntawv no tseem ceeb rau kev ua phem rau kev sib tsoo hauv nitric acid, tsis hais txog lawv cov vuam lossis cua sov keeb kwm. Nco ntsoov qhia cov ntawv txuas welded thaum qhia cov cua sov rau kev lag luam tshuaj nitric acid. Qhia meej 316L (tsis yog tus qauv 316) rau txhua daim ntawv thov siab dua 15% concentration lossis 50 ° C. Intergranular quab yuam ntawm cov ciam teb ua rau propagates flange detachment ntawm ib tug welded 1.6 hli sheath nyob rau hauv nitric acid thiab feem ntau tshwm sim nrog me ntsis kev ceeb toom. Kev xaiv cov khoom tsim nyog thiab kev tswj hwm watt ceev yog qhov tseem ceeb rau kev txhim khu kev qha ntawm cov tshuaj reactors.