Yuav Ua Li Cas Thermal Expansion Mismatch Ntawm Titanium Heater Tube thiab Nws Mounting Flange Influence Cyclic Fatigue Lub Neej Nyob Hauv Chav Dej?

Titanium rhaub tubes yog siv nyob rau hauv chav cua sov daim ntaub ntawv rau immersed nyob rau hauv condensate los yog nyob rau hauv kev sib cuag ncaj qha nrog chav ntawm kub ntawm 100℃mus rau 160 degree. Lub raj cua sov feem ntau yog welded lossis mechanically txuas rau lub flange mounting ntawm ib qho khoom sib txawv, feem ntau yog carbon steel, stainless hlau los yog PTFE-lined steel. Txhua yam khoom muaj nws tus kheej Coefficient of Thermal Expansion (CTE). CTE ntawm Titanium Qib 2 yog kwv yees li 8.6 × 10-6 /℃. CTE ntawm carbon steel yog 12.0 × 10⁻⁶ / degree. Stainless hlau 316 CTE=16.0 x 10-6 /℃Chav cua sov cycles yog cua sov lub cev los ntawm ambient (20 degree) mus rau ua hauj lwm kub (120-160 degree) thiab txias. Qhov sib txawv ntawm kev nthuav dav ntawm titanium raj thiab nws cov flange mounting tsim kev ntxhov siab rau ntawm qhov chaw txuas. Qhov thermal expansion mismatch no ua rau qaug zog tawg feem ntau ntawm cov ntiv taw ntiv taw los yog raj-flange interface ntau pua lossis ntau txhiab lub voj voog.

Thermal qaug zog mechanism vim mismatch ntawm CTE

Raws li lub kaw lus cua sov, lub mounting flange nthuav ntau tshaj li titanium raj (rau steel flanges) los yog tsawg tshaj li titanium raj (rau qee cov alloys tshwj xeeb). Lub raj yog txwv ntawm qhov chaw txuas los ntawm flange. Qhov kev txwv no ua rau muaj kev ntxhov siab nyob rau hauv lub raj - tensile stresses thaum lub flange nthuav ntau dua titanium thaum cua sov thiab compressive stresses thaum txias. Qhov loj ntawm cyclic strain yog proportional rau cov khoom ntawm CTE qhov sib txawv, qhov kub thiab txias viav vias, thiab qhov deb ntawm qhov nruab nrab axis. Rau ib txwm 200 mm ntev los ntawm flange lub ntsej muag rau thawj qhov kev txhawb nqa, 100℃kub viav vias nrog CTE qhov sib txawv ntawm 4 × 10-6 /℃muab txog 0.08 mm txawv txav txhua lub voj voog. Qhov kev hloov pauv no, nyob hauv thaj chaw ntawm qhov sib txuas los yog kev sib koom ua ke, ua rau cov kab mob hauv zos ntau dua 0.2%, zoo nyob rau hauv qhov qis qis qis.

Fatigue Life Quantitative Raws li cov khoom siv flange

Lub neej qaug zog hauv qab no tau txais rau Qib 2 titanium raj tau koom nrog ntau yam khoom siv flange siv kev ntsuas lub voj voog (100℃kub viav vias, 5 feeb cua sov, 5 feeb txias):

Titanium flange (muab CTE, 8.6 x 10-6 / degree): qaug zog lub neej> 100,000 cycles. Tsis sib xws ntawm thermal expansion. Weld tsuas hnov ​​​​lub siab thiab kev vibration stresses. Nyiam layout rau chav cua kub siab cycling.

Carbon steel flange (CTE mismatch ntawm 3.4 x 10-6 / degree) qaug zog lub neej ntawm 8,000-12,000 mus txog thaum tawg pib. Cov kab nrib pleb feem ntau tshwm nyob ze ntawm cov ntiv taw ntiv taw tom qab 5,000 txog 7,000 lub voj voog. Haum rau kev siv tsawg dua 2 lub voj voog ib hnub (10+ xyoo lub neej).

Stainless hlau 316 flange (CTE mismatch 7.4 × 10⁻⁶ / degree): qaug zog lub neej 2,500–4,000 mus txog rau thaum pib tawg. Qhov loj CTE mismatch ua rau muaj kev ntxhov siab loj heev. Tsis siv rau kev caij tsheb kauj vab txhua hnub.

Inconel Flange (CTE 13.0 × 10−6 / degree, mismatch 4.4 × 10−6 / degree): qaug zog lub neej 1,500–2,500 cycles Zoo li stainless hlau. Titanium{11}}Inconel weld kuj ua rau muaj kev pheej hmoo ntawm galvanic corrosion hauv cov condensate.

PTFE lined steel flange (PTFE CTE 100 x 10⁻⁶ /℃tab sis txwv los ntawm cov hlau): Cov cwj pwm nyuaj. Lub PTFE liner deforms plastically, txo qhov kev txwv ntawm titanium raj. Zoo liner tsim, qaug zog lub neej 15,000-20,000 cycles.

Chav Cua Kub Kev Pabcuam Flange Cov Khoom Xaiv Qhia

Cov lus hauv qab no muab cov txheej txheem kev txiav txim siab rau kev xaiv cov khoom siv flange mounting raws li qhov zaus ntawm lub voj voog cua sov thiab kev ua haujlwm kub.

Chav Cua Kub Cycle Zaus & Kub Pom Zoo Flange Khoom CTE Mismatch Solution<1/day cycle, 100-120o C steamFlexible transition piece for carbon steel titaniumLow cycle count carbon steel is fine. Use a thin (2 mm) titanium spacer for stress distribution.
1-5 cycles / hnub, 120-140℃chav Titanium flange (Qib 2) ncaj qha welded rau tubeThermal qaug zog raws li ib tug tsis ua hauj lwm hom yog tshem tawm nrog matched CTE. Flange muaj tus nqi pib dua.
5-20 cycles ib hnub twg, chav nyob ntawm 140-160℃Titanium flange nrog lub hauv siab expansion jointBellows muab kev nthuav dav sib txawv. Yuav tsum tau siv rau lub voj voog hnyav. Ntev ntev ntev ua kom pom tseeb tus nqi ntxiv.
Cov pa roj carbon steel flange uas twb muaj lawm, nquag caij tsheb kauj vab yuav tsum tau rov ua dua nrog hloov pauv graphite gasket (thickness 3 mm) Gasket compresses 0.3-0.5mm ib lub voj voog, absorbs thermal hloov. Kev hloov gasket txhua xyoo.
Cov cua kub cua sov nrog dej quench (thermal shock, ceev txias) Titanium flange nkaus xwb ceev cycling tsub kom CTE mismatch teebmeem. Txhua qhov sib txawv hlau flange yuav poob hauv 500 cycles.
Engineering Tshaj Flanged Khoom nkaus xwb

Lub raj txoj kab uas hla thiab phab ntsa thickness cuam tshuam qhov kev ntxhov siab concentration ntawm flange txuas. Ib txoj kab dav dav ntawm lub raj (50 mm vs 25 mm) faib cov kab mob sib kis thoob plaws lub vojvoog loj dua uas txo cov kev ntxhov siab hauv zos los ntawm 30 - 40%. Phab ntsa tuab (2.0 hli vs . 1.0 hli) muab kev tiv thaiv ntau dua rau kev nthuav tawm ntawm kev qaug zog tawg thaum nws pib. Kev tsim cov vuam yog qhov tseem ceeb zoo ib yam: kev nkag mus rau qhov sib txuas nrog kev hloov pauv (tsis muaj qhov tob tob ntawm lub raj -flange junction) txhim kho lub neej qaug zog los ntawm 3-5 zaug piv rau fillet weld nrog undercut. Tom qab-weld stress alleviation (550℃rau 30 feeb) txo qhov seem welding stresses uas nce mus rau thermal cycle stresses.

Kev ntseeg ruaj khov

Thaum txiav txim lub titanium rhaub raj rau chav cua sov kev pab, xaiv ib tug titanium flange ntawm zoo tib yam li cov khoom siv raj. Yog hais tias kev txwv nyiaj txiag txwv tsis pub siv cov pa roj carbon steel flange rau ib daim ntawv thov, qhia txog qhov hloov pauv hloov tau yooj yim -ib 50-100 mm ntev ntawm nyias- phab ntsa titanium tubing (0.8 mm)- nruab nrab ntawm cov flange nruj thiab cov cua sov raj. Qhov ua tau raws li qhov deforms elastically thaum kub caij tsheb kauj vab thiab absorbs expansion mismatch yam tsis muaj kev puas tsuaj rau lub vuam. Nrhiav tus naj npawb ntawm cov thermal voj voog nyob rau lub neej ntawm lub rhaub. Hloov pauv hloov cov pa roj carbon steel rau 10,000 lossis tsawg dua yog qhov siv tau. Qhia meej titanium flange tsuas yog rau cov voj voog ntau dua 10,000. Tshawb xyuas lub raj- flange weld siv cov dye penetrant txhua xyoo thaum ua haujlwm. Txhua txoj kab tawg yuav tsum tau kho lossis hloov ib zaug. Tus kws tshaj lij zam tsis txhob zais qhov ua tsis tiav los ntawm thermal qaug zog ntawm chav{18}}rhaub tshuab los ntawm kev sib piv cov khoom flange rau titanium raj lossis los ntawm kev muab kev ntxhov siab{19}} nqus cov yam ntxwv.