Hauv Flue Gas Desulfurization Scrubbers ntawm 70 degree, Yuav Ua Li Cas Chloride Concentration Saum 20,000 ppm Dictate Yam Tsawg Titanium Tube Phab Ntsa rau Kev Tiv Thaiv Pinhole?

Coal- cov chaw tsim hluav taws xob hluav taws xob thiab cov boilers muaj qhov nruab nrog flue gas desulfurization (FGD) scrubbers uas ua haujlwm nyob rau hauv qee qhov feem ntau corrosive ntawm cov khoom ib puag ncig. Cov kua tshuaj txhuam hniav yog cov sib tov sib xyaw ntawm calcium sulfite / sulfate, ya tshauv thiab yaj chlorides uas mloog zoo li lub voj voj voog rov ua dua. Titanium Qib 2 yog cov khoom siv ntawm kev tsim kho rau cov raj reheater thiab cov tshuaj tsuag taub hau hauv FGD systems vim nws tsis kam mus rau sulfite nres. Txawm li cas los xij, cov tshuaj chloride feem ntau ntau dua 20,000 ppm (2%) hauv FGD cov tshuaj txhuam hniav thiab tuaj yeem ncav cuag 50,000-80,000 ppm hauv xoom- kua- tso tawm tshuab. Ntawm cov chloride concentrations titanium yog rhiab rau pitting thiab crevice corrosion thiab tsuas yog tiv thaiv los ntawm-phab ntsa perforation yog lub raj phab ntsa nws tus kheej, ob qho tib si thickness thiab metallurgical zoo. Kab lus no nthuav tawm qhov tsawg kawg nkaus titanium raj phab ntsa thickness yuav tsum tau txwv tsis pub pinhole perforation raws li kev ua haujlwm ntawm chloride concentration, kub thiab crevice hauv FGD scrubber pabcuam.

Pitting ntawm cov hlau hauv High Chloride FGD cawv
Lub pitting corrosion ntawm titanium nyob rau hauv siab -Cl thiab qis-pH FGD nqis ua raws li qhov zoo-cov ntaub ntawv pib- nthuav tawm qauv. Qhov kev puas tsuaj ntawm cov yeeb yaj kiab TiO 2 passive tshwm sim ntawm qhov chaw sib cais uas cov tshuaj chloride ions hloov oxygen hauv cov zaj duab xis lattice. Thaum pib lub qhov, cov kua qaub chloride hauv lub qhov dej (pH tuaj yeem poob mus rau 1-2) txuas ntxiv ua kom muaj kev sib cais, thaum qhov chaw nyob ib puag ncig tiv thaiv. Lub qhov dej nthuav dav hemispherically thiab lub sijhawm rau perforation yog kwv yees li proportional rau lub square ntawm phab ntsa thickness rau ib qho kev loj hlob ntawm lub qhov.

Qhov tseem ceeb pitting kub (CPT) ntawm Qib 2 titanium hauv cov tshuaj chloride txo qis nrog kev nce chloride concentration. Ntawm pH ntawm 4 (ib txwm ntawm FGD scrubbers), 20,000 ppm Cl- muab CPT ntawm li 85℃, siab dua qhov nruab nrab cov tshuab ntxhua khaub ncaws ua haujlwm kub ntawm 70℃thiab muab kev nyab xeeb. Ntawm 40,000 ppm Cl- CPT txo qis rau 70 degree, piv txwv li lub tshuab ntxhua khaub ncaws ua haujlwm raws nraim ntawm qhov pib. CPT poob rau 55℃ntawm 60,000 ppm Cl- thiab active pitting tuaj yeem tshwm sim ntawm qhov kub thiab txias. Tus nqi ntawm qhov propagation nce logarithmically nrog nce chloride concentration: ntawm 20,000 ppm Cl- thiab 70℃ib propagating qhov tob tob ntawm 0.2-0.3 hli ib xyoo; ntawm 40,000 ppm Cl- tus nqi yog 0.5-0.8 hli ib xyoos; ntawm 60,000 ppm Cl- tus nqi ntawm 1.0-1.5 hli ib xyoo raug kaw.

Phab ntsa Thickness: Txoj Kev Tiv Thaiv Pinhole
Qhov tsawg kawg nkaus phab ntsa thickness yuav tsum tau muab 5 xyoo kev pab cuam lub neej yam tsis muaj pinhole perforation ntawm FGD scrubber heaters thiab raj bundles yog nyob ntawm seb qhov kwv yees qhov propagation npaum li cas thiab cov statistical faib ntawm qhov chaw pib. Tus qauv kev loj hlob ntawm lub qhov (qhov tob=k * t^0.5 qhov twg k yog ib qho kev ua ntawm chloride concentration) yog siv thiab lub raj lub neej yuav tsum tau txiav txim siab los ntawm qhov tob tshaj plaws. Qhov xav tau phab ntsa thickness yog xam raws li:

Lub qhov propagation tas li k ntawm 20,000 ppm Cl - yog 0.28 mm / xyoo ^ 0.5. Rau 5 xyoos lub neej, max qhov tob=0.28 × √5=0.63 mm. Qhov kev nyab xeeb ntawm lub 1.2 hli phab ntsa raj yog hais txog 0.6 hli, uas yog txaus rau cov raj huv si uas tsis muaj teeb meem preexisting.

40,000 ppm Cl- k=0.48 mm/xyoo^0.5 Qhov siab tshaj plaws qhov tob hauv 5 xyoos=0.48 * sqrt(5)=1.07 mm. 1.65mm phab ntsa raj muab cov npoo, 1.2mm raj yuav perforate.

k=0.70 hli / xyoo 0.5 ntawm 60,000 ppm Cl-. Qhov siab tshaj plaws ntawm qhov tob hauv 5 xyoos=0.7 × √5=1.57 mm. Lub 2.0 hli phab ntsa raj yog tsim nyog rau txhim khu kev qha 5 xyoo kev pab cuam . 1.65 hli yuav tsuas muab 3-4 xyoo.

Titanium Tubes rau FGD Scrubber Daim Ntawv Thov Matrix
FGD System Hom Hom Tshuaj Chloride ConcentrationRecommended Titanium Qib Yam Tsawg Phab Ntsa Thickness Kev Pabcuam Lub Neej
Coal fired fais fab nroj tsuag, ntub limestone (los ntshav kwj tswj) 15,000-25,000 ppm Qib 2 1.2-1.5 hli 5-8 xyoo
Coal fired fais fab nroj tsuag, siab chloride thee 25,000-40,000 ppm Qib 2 los yog Qib 7 1.65 hli 4-6 xyoo
Zero-kua- tso tawm FGD (kaw voj) 40,000-60,000 ppm Qib 7 (Ti-0.15Pd) 2.0 hli 5-7 xyoo
Muaj boiler FGD (variable thee) 10,000-20,000 ppm Qib 2 .8-.12 hli 8-10 xyoo
Pov tseg-rau-zog FGD (siab chloride los ntawm pov tseg) 50,000-80,000 ppm Qib 12 lossis Qib 7 2.5 hli 4-6 xyoo
Tube Quality Thiab Crevice teeb meem
Ua ntej- cov crevices nyob rau hauv lub raj tsis tiv thaiv pinhole perforation, txawm tias phab ntsa thickness yog nce. Hauv kev pabcuam FGD scrubber, crevices muaj nyob rau ntawm lub raj - mus rau -tubesheet dov cov pob qij txha, hauv qab gaskets thiab nyob rau hauv deposits ntawm gypsum los yog ya tshauv. Crevice corrosion nce tus nqi ntawm qhov pib thiab nthuav tawm los ntawm ib qho ntawm 3-10. Welded tube-to-tubesheet junctions (tsis muaj fissures) yog nyiam rau dov los yog flanged kev sib txuas ntawm tej chloride concentration siab tshaj 20,000 ppm. Tube nto yuav tsum tsis muaj nplai, embedded hlau hais (los ntawm kev tsim cov cuab yeej), thiab nto khawb tob tshaj 10 feem pua ​​ntawm phab ntsa thickness. Qhov zoo tshaj pitting kuj yog muab los ntawm electropolished los yog pickled tiav.

Rau FGD scrubbers ua haujlwm ntawm 70℃nrog chloride concentrations siab tshaj 20,000 ppm, qhov tsawg kawg nkaus titanium raj phab ntsa thickness ntawm 1.65 hli yog yuav tsum tau rau Qib 2 nyob rau hauv nruab nrab concentrated systems (20,000-40,000 ppm), nce mus rau 2.70 mm. forde 0 ppm. Cov kws kho tsheb yuav tsum tau hais kom cov khoom siv los yog electropolished tube nto, welded es tsis yog dov raj -to-tubesheet pob qij txha thiab saib xyuas cov tshuaj chloride concentration txhua lub lim tiam kom paub txog kev ntxhov siab ua ntej pitting perforation tshwm sim. Rau cov tshuaj chloride ntau dua 60,000 ppm, lwm cov ntaub ntawv xws li qib 12 titanium lossis zirconium yuav tsum raug txiav txim siab.