Thermal Shock Challenge nyob rau hauv Batch Caustic Cua sov
Batch caustic soda tanks voj voog ntawm 15℃(them nqi tshiab) mus rau 80℃(txheej txheem kub) thiab rov qab thaum lub sij hawm ntws thiab refill. Thaum cov cua sov raug rau qhov txias caustic tom qab ua haujlwm kub, thermal shock kev ntxhov siab tshwm sim. PFA phab ntsa thickness txiav txim siab tiv thaiv tawg los ntawm cov kev hloov kub ceev no. Kev txheeb xyuas ntau los ntawm 18 cov chaw ua haujlwm caustic qhia tau hais tias 1.5mm PFA phab ntsa muaj sia nyob 800-1200 cycles ua ntej tawg. Phab ntsa ntawm 2.5mm ciaj sia 1800-2500 cycles, thiab 3.0mm phab ntsa tshaj 3000 cycles.
Thermal Shock Mechanism thiab Stress Calculation
Thaum lub cua sov PFA kub (80 degree) yog dheev immersed nyob rau hauv txias caustic (15 degree), lub nto daim ntawv cog lus sai sai thaum lub sab hauv tseem nthuav. Qhov no tsim tensile kev nyuaj siab rau saum npoo, xam raws li σ=E × × ΔT / (1-ν), qhov twg E yog modulus (480 MPa ntawm 80 degree), yog expansion coefficient (120 ppm / degree), ΔT yog 65 degree, thiab ν yog Poisson tus piv (0.46). Theoretical stress yog 480 × 120e-6 × 65 / 0.54=6.9 MPa. PFA tensile lub zog yog 25-28 MPa, yog li ib qho kev poob siab tsis ua rau tsis ua haujlwm. Txawm li cas los xij, kev rov ua dua tshiab ua rau qaug zog tawg pib thiab nthuav tawm.
Cycle Life vs. Phab ntsa Thickness
Kev ntsuas nrawm nrog tag nrho 80℃txog 15℃quenches hauv 50% NaOH, nrog rau huab cua kis ntawm lub voj voog (tsis muaj kev yuam kom txias):
| Phab ntsa Thickness (mm) | Thermal Stress ntawm Surface (MPa) | Lub voj voog mus rau Thawj Pom Pom Crack | Lub voj voog mus dhau -Pab ntsa tawg | Hom kev ua tsis tiav |
|---|---|---|---|---|
| 1.5 hli | 6.9 | 800 | 1,200 | Nto crazing → propagation |
| 2.0 hli | 6.9 | 1,100 | 1,800 | Crack pib ntawm threads |
| 2.5 hli | 6.9 | 1,500 | 2,500 | Crack propagation qeeb |
| 3.0mm ib | 6.9 | 2,000 | 3,500+ | Txwv rau qhov chaw |
Crack Initiation Sites thiab Phab Ntsa Thickness
Cov kab nrib pleb pib ntawm cov ntsiab lus kev ntxhov siab: cov kab pwm, qhov chaw tsis xws luag, lossis kev hloov pauv haum. Cov phab ntsa Thicker faib kev ntxhov siab ntau dua cov khoom siv, txo cov kev ntxhov siab siv ntawm cov lus qhia tawg. Rau qhov muab qhov tsis haum loj ntawm 50µm:
Hauv 1.5mm phab ntsa, tawg propagates los ntawm 1.45mm ntawm cov khoom seem
Hauv 3.0mm phab ntsa, tawg yuav tsum nthuav tawm los ntawm 2.95mm, noj 3x ntau lub voj voog
Tsis tas li ntawd, cov phab ntsa tuab muaj qhov qis qis dua -vim qhov kub thiab txias gradients vim tias lub sij hawm thermal diffusion ntsuas nrog thickness squared.
Quench Severity thiab Cycle Rate
Qhov sib txawv ntawm 65℃qhov sib txawv nruab nrab yog kev caij tsheb kauj vab. Cov quenches hnyav dua (piv txwv li, 80℃txog 5 degree, 75℃ΔT) nce kev ntxhov siab los ntawm 15% thiab txo lub neej voj voog los ntawm 50% rau tag nrho cov thicknesses. Cov quenches qeeb qeeb (tswj-nyob rau hauv qhov txias caustic tshaj 60 vib nas this vs. 5 vib nas this) txo qhov ua tau zoo ΔT los ntawm kev tso cai rau qee qhov ua ntej- txias. Cycle rate kuj tseem ceeb: 10 lub voj voog ib hnub twg (kev caij tsheb kauj vab nrawm) ua rau qaug zog ntau dua 1 lub voj voog ib hnub vim muaj sij hawm tsawg rau kev ntxhov siab ntawm cov xwm txheej.
Fitting thiab Termination Effects
Qhov chaw txiav tawm qhov twg PFA ua tau raws li kev sib txuas hluav taws xob yog qhov chaw pib tawg vim qhov kev nyuaj siab geometric concentration. Phab ntsa thickness ntawm kev txiav yog feem ntau txo los ntawm compression fittings. Rau siab - voj voog daim ntawv thov, qhia meej molded terminations nrog ib tug strain nyem, tuav tag nrho phab ntsa thickness rau cov hluav taws xob vaj tse. Tsis txhob siv cov tshuab compression fittings ncaj qha rau PFA, uas tsim cov ntawv sau. Rau 1.5 hli phab ntsa, 80% ntawm thermal poob siab tshwm sim ntawm kev txiav; rau 3.0mm phab ntsa, tsuas yog 30%.
Phab ntsa Thickness xaiv los ntawm Cycle Requirement
| Cia siab rau lub voj voog dhau lub neej rhaub | Pom zoo Phab ntsa Thickness | PFA Qib | Termination Hom |
|---|---|---|---|
| < 500 | 1.5 hli | Txuj | Ib qho |
| 500-1000 | 1.8mm ib | Txuj | Moulded |
| 1000-1500 | 2.0 hli | Siab molecular hnyav | Moulded nrog strain nyem |
| 1500-2000 | 2.5 hli | Siab molecular hnyav | Moulded nrog strain nyem |
| 2000-3000 | 3.0mm ib | Siab molecular hnyav + annealed | Integral molded |
| > 3000 | 3.5mm ib | Kev cuam tshuam - hloov | Integral molded |
Specification Guide rau Batch Caustic rhaub
For batch caustic soda tanks cycling from 15°C to 80°C, specify PFA heater wall thickness based on expected cycles: 2.0mm for up to 1500 cycles, 2.5mm for 1500-2500 cycles, 3.0mm for >2500 cycles (ib txwm 5- xyoo ua haujlwm ntawm 1 lub voj voog ib hnub=1825 cycles). Yuav tsum tau muab ntawv pov thawj ntawm kev ntsuam xyuas thermal shock: 1000 cycles ntawm 80℃mus rau 15℃hauv 50% NaOH uas tsis muaj kab nrib pleb pom ntawm 20x magnification. Rau siab - daim ntawv thov mus ncig, qhia meej txog kev tshem tawm PFA (kev ntxhov siab-relieved) thiab molded terminations nrog ib tug strain nyem. Thaum thov cov lus hais, muab qhov xav tau lub voj voog zaus thiab caustic concentration. Tus nqi them rau 3.0mm vs . 1.5mm phab ntsa (30-40%) yog qhov tsim nyog los ntawm 3x lub neej ntev dua hauv kev pabcuam thermal caij tsheb kauj vab, txo qis qis qis rau kev hloov lub rhaub. Rau kev ua haujlwm tas mus li 24/7 nrog kev caij tsheb kauj vab tsis tshua muaj, 1.5mm phab ntsa yog tsim nyog.
