Ntawm Dab tsi tshwj xeeb kev sib xyaw ntawm Sulfuric Acid Concentration thiab Kub Puas Yog 2.0 millimeter 316 Stainless Steel Sheath Yuav Tsum Tau Derating hauv qab 5 Watts Ib Square Centimeter los tiv thaiv kev xeb hauv cov hlau da dej?

Cov txheej txheem engineers tsim hluav taws xob immersion heaters rau hlau pickling da dej nyob rau hauv steel mills thiab hlau fabrication industries ntsib ib tug ntawm cov feem ntau hnyav tej yam kev mob rau 316 stainless hlau sheaths thaum ntsib nrog sulfuric acid ntawm huab cua kub. Pickling da dej feem ntau ua haujlwm ntawm qhov kub ntawm 60 mus rau 90℃thiab sulfuric acid concentrations ntawm 10 mus rau 25%, feem ntau nrog cov ntsev yaj ntsev, uas ua rau muaj kev cuam tshuam rau tus cwj pwm corrosion ntxiv. A 2.0 hli phab ntsa thickness feem ntau yog xaiv los tso cai rau corrosion thiab muab cov neeg kho tshuab resilience rau da dej turbulence thiab kev sib cuag nrog lub workpiece. Txawm li cas los xij, kev khiav ntawm ib txwm watt ntom ntom ntawm 8-12 W / cm2 ua rau lub plhaub ntawm qhov kub thiab txias yog 20-40oC siab tshaj qhov kub da dej, uas tuaj yeem ua rau lub plhaub nkag mus rau hauv cov txheej txheem tiv thaiv corrosion nrog corrosion ntawm ntau dua 5 hli hauv ib xyoos. Nyob rau hauv daim ntawv no, peb txheeb xyuas qhov sib xyaw ua ke ntawm qhov sib xyaw ua ke uas muaj 2.0 hli 316 sheath yuav tsum tau derated qis dua 5 W / cm2 kom nyob twj ywm hauv qhov kev tiv thaiv corrosion passive.

316 Stainless Hlau nyob rau hauv Sulfuric Acid: Kev Hloov ntawm Passive mus rau Active
Tshooj 30 hais tias nyob rau hauv sulfuric acid qhov passive - nquag hloov pauv ntawm 316 stainless hlau yog nyob ntawm qhov kub thiab txias. Corrosion tus nqi yog <0.2 hli yr−1 nyob rau hauv passive regime. Nyob rau hauv cov kev tswj hwm tus nqi yog 5-20 hli ib xyoos. Lub pas dej da dej hloov pauv ciam teb ua raws li qee qhov nkhaus. Kev hloov pauv kub rau 10 feem pua. sulfuric acid yog hais txog 55℃C. Ntawm 15% yog 45℃kev hloov. Ntawm 20% nws poob rau 38 degree. Nws nce mus txog 32℃. - 25%. Rau lub rhaub dej kub hauv ib da dej ntawm 70℃nrog 15% sulfuric acid, cov xwm txheej ib leeg twb dhau ntawm 45℃kev hloov pauv kub - lub da dej yog nquag corrosive mus rau 316 yam tsis muaj cua sov flux . 316 tsis tsim nyog nyob rau hauv cov xwm txheej no tsis hais txog ntawm phab ntsa tuab lossis watt ntom. Txawm li cas los xij, ntau lub pas dej da dej yog nyob rau hauv qhov chaw hloov pauv uas cov xwm txheej feem ntau dhau mus, tab sis qhov kub ntawm qhov kub thiab txias, vim yog cua sov flux, thawb lub plhaub rau hauv kev ua haujlwm. Qhov kub nce los ntawm qhov ntau mus rau qhov chaw sheath yog nyob ib ncig ntawm 25-30℃rau lub plhaub ntawm 2.0 hli ntawm 10 W / cm². Kev da dej ntau ntawm 40℃nrog 15% acid (passive) ua rau lub qhov txhab ntawm qhov kub ntawm 65-70 degree, uas tshaj li qhov hloov pauv ntawm 45 degree, yog li muaj kev cuam tshuam corrosion tshwm sim ntawm lub qhov txhab txawm hais tias qhov ntau da dej yog passive.

Critical Derating Thresholds 2.0 millimeter Sheath
Derating xav tau los ntawm kev ntsuam xyuas corrosion ntawm 316 cov qauv, ntawm qhov kub thiab txias thiab qhov muaj feem cuam tshuam rau cov da dej pickling, yog raws li hauv qab no. Sheath nrog 2.0 hli phab ntsa. Values ​​are the maximum watt density that maintains the sheath surface temperature at least 5℃below the passive-active transition temperature for the given bulk concentration.

Bulk Sulfuric Acid Concentration Bulk Bath Temperature Passive-Active Transition Temperature at This Concentration Maximum sheath deg kub (hloov – 5℃kev nyab xeeb margin)Max. Tso cai Watt Density rau 2.0 mm. Sheath Pom Zoo Ua Haujlwm 10% 30℃55℃50℃12 W / cm² Safe ntawm tus qauv watt ntom
10% 40℃55℃50℃6 W/cm² Derate 10% 45℃55℃50℃3 W/cm2 Marginal; Xav txog kev hloov kho cov hlau 10% Saum 48℃55℃50℃Tsis ua tau Titanium lossis Alloy 20
15% 25oC 45oC 40oC 10 W / cm2 Muaj kev nyab xeeb hauv nruab nrab watt ceev
15% 30℃45℃40℃6 W / cm² Derating tsim nyog
15% 35℃45℃40℃2 W / cm2 Tsis siv tshuaj hloov pauv
15% Tshaj 38℃45℃40℃Tsis tau 316 tsis ua tau
20% 20℃38℃33℃8 W / cm² Safe ntawm tsawg watt ceev
20% 25C 38C 33C 4 W / cm2 Loj derating 20% ​​Saum 28C 38C 33C Tsis tau 316 tsis haum
25% <25°C 32°C 27°C <3 W/cm² 316 not recommended
25% > 25℃32℃27℃Tsis siv tau Alloy 20 lossis Titanium
Rau ib tug raug pickling da dej ntawm 15% sulfuric acid thiab 35℃tej kub, lub 2.0 hli 316 sheath yuav tsum nyob rau hauv los yog qis dua 2 W / cm2 los tiv thaiv active corrosion. Ntawm qhov watt ceev no lub rhaub yuav yog lub tshuab ua kom ntev ntev rau qhov xav tau ntawm lub zog nruab nrab ntawm 10-20 kW. Yog li 316 tsis yog qhov haum rau qhov kev pabcuam no. Cov kws kho tsheb yuav tsum xav txog kev siv Alloy 20 (Carpenter 20) los yog Alloy 825, ob qho tib si uas muaj kev hloov pauv hloov pauv mus txog 30-50℃siab dua 316 hauv sulfuric acid.

Tsim cov kev hloov pauv kom tiv thaiv kom tsis txhob muaj kev cuam tshuam tsis muaj derating
Yog tias cov dej khib nyiab nyob ze rau ntawm thaj tsam hloov pauv thiab 2.0 hli 316 sheath twb nyob rau hauv qhov chaw lossis tsim nyog, peb qhov kev hloov kho tuaj yeem zam tsis txhob muaj kev cuam tshuam tsis muaj kev poob qis hauv watt ceev hauv qab cov kev txwv. Thawj yog txhawm rau txhim kho cov kua qaub thoob plaws hauv qhov chaw cua sov. Lub turbulent flow nrog lub nrawm ntawm 1-2 m / s txo qhov kub nce ntawm lub plhaub ntawm 25-30 mus rau 10-15 degree, uas tuaj yeem tiv thaiv lub plhaub ntawm qhov kev hloov pauv. Qhov kev hloov pauv thib ob yog ntxiv tus neeg sawv cev oxidizing hauv da dej. Ntxiv me me ntawm ferric ions los yog ntawm hydrogen peroxide tuaj yeem hloov qhov passive - nquag hloov mus rau qhov kub siab dua los ntawm 10-20 ° C, rov qab mus rau tus cwj pwm tsis zoo. Qhov thib peb kev hloov pauv yog qhov dual-watt-density heater design uas muaj zog qis dua nyob rau hauv qis qis ntawm chav da dej nrog qhov kub siab tshaj plaws vim yog stratification . Rau feem ntau pickling da dej daim ntaub ntawv cov kev daws teeb meem engineering yog hloov kho los ntawm 316 mus rau ib tug ntau resistant alloy. Feem ntau tus nqi sib txawv ntawm 2.0 mm 316 sheath thiab Alloy 20 sheath ntawm tib qhov loj yog 30-50%, tab sis lub neej kev pab cuam txhim kho los ntawm lub hlis mus rau 5-10 xyoo. Thaum qhia cov cua sov rau pickling da dej, engineers yuav tsum muab tus neeg muag khoom nrog tag nrho cov muaj pes tsawg leeg ntawm lub da dej, qhov kub thiab txias qhov ntau thiab cov℃ntawm turbulence xav. Yog tias cov chaw tsim khoom pom zoo 316 rau 15% sulfuric acid ntawm 50℃thiab tsis tham txog derating lossis muaj peev xwm ua kom muaj zog corrosion, lawv tsis muab cov lus qhia muaj peev xwm. Kev hloov ntawm passive mus rau active corrosion nyob rau hauv sulfuric acid yog ceev thiab merciless. Ib lub 2.0-mm sheath uas poob 5 hli / xyoo hauv active corrosion yuav perforate nyob rau hauv tsawg dua 5 lub hlis. Derating<5 W/cm 2 is seldom feasible for commercial pickling baths, therefore alloy upgrade remains the only reliable remedy for most applications.