1. Nyob rau hauv hierarchy ntawm corrosion{1}}cov alloys resistant, dab tsi yog lub hauv paus ntsiab lus ntawm kev tsim lub tswv yim uas txawv Hastelloy C-276 los ntawm C-22, thiab qhov no qhia lawv li cas hauv kev lag luam txheej txheem tshuaj?
Qhov tseem ceeb sib txawv yog nyob rau hauv lawv lub hom phiaj optimization nyob rau hauv lub spectrum ntawm corrosive ib puag ncig, txav los ntawm ib tug superb, balanced "workhorse" mus rau lub hom phiaj txhim kho "premium" alloy. Ob leeg yog npib tsib xee-chromium- molybdenum (Ni-Cr-Mo) alloys tsim los rau cov mob hnyav tshaj plaws, tab sis lawv cov tshuaj tweaks hloov lawv cov kev ua tau zoo.
Hastelloy C-276 (UNS N10276) - Cov pov thawj, cov neeg ua haujlwm sib npaug.
Lub tswv yim tom qab C-276, tsim nyob rau hauv 1960s, yog los tsim ib qho alloy nrog tshwj xeeb, ntau yam tsis kam mus rau ob qho tib si oxidizing thiab txo cov tshuaj, thaum daws qhov teeb meem weld lwj ntawm nws cov neeg ua ntej (xws li alloy C). Nws cov nominal muaj pes tsawg leeg (~ 57Ni, 16Cr, 16Mo, 4W, qis C / Si) yog ib tug masterclass nyob rau hauv equilibrium. 16% Cr tuav oxidizing media (nitrates, ferric chlorides, yaj oxygen), 16% Mo plus Tungsten tackles txo cov kua qaub (HCl, H₂SO₄) thiab pitting / crevice nres los ntawm chlorides. Cov qib qis carbon thiab silicon tseem ceeb ua rau nws zoo heev "raws li -welded" stability, lub ntsiab lus fabricated cov hlab ntsha thiab cov kav dej tsis tas yuav tsum tau tom qab vuam thaum tshav kub kub kho kom muaj corrosion kuj. C-276 yog lub neej ntawd, kev xaiv txhim khu kev qha rau ntau yam tsis paub lossis sib xyaw chemistry, xws li hauv cov tshuab flue gas desulfurization (FGD), tshuaj synthesis, thiab kev kho cov khib nyiab.
Hastelloy C-22 (UNS N06022) - Kev Txhim Kho, Ua kom zoo dua qub.
Tsim nyob rau xyoo 1980, C-22 lub tswv yim yog txhawm rau txuas lub hnab ntawv ua haujlwm, tshwj xeeb tshaj yog nyob rau hauv oxidizing heev, localized corrosion, thiab sib xyaw acid ib puag ncig. Nws kho qhov sib npaug: siab dua Chromium (~ 22%) thiab qis Molybdenum (~ 13%), nrog ntxiv Tungsten (~ 3%). Qhov no ua rau kom muaj zog tiv thaiv oxidizing kev daws teeb meem (xws li, kub, paug nitric acid, hypochlorite) thiab, qhov tseem ceeb, nce qhov tseem ceeb ntawm qhov kub thiab txias (CPT) thiab Critical Crevice Temperature (CCT) hauv chlorides txhoj puab heev. Nws muaj kev ua tau zoo tshaj qhov twg oxidizing ntsev (FeCl₃, CuCl₂) tam sim no. Thaum tseem muaj cov khoom zoo li-welded, nws cov chemistry txhim kho feem ntau ua rau nws qhov kev xaiv zoo tshaj plaws rau thaj chaw tseem ceeb tshaj plaws hauv kev ua tshuaj lom neeg, xws li cov khoom siv hluav taws xob tuav cov halogenated organics lossis rau kev tswj cov pa phem nrog cov tshuaj chloride hnyav.
Kev taw qhia rau kev thov:
Xaiv C-276 rau kev ua pov thawj, kev ua tau zoo raug nqi thoob plaws ntau yam kev mob hnyav, tab sis tsis yog huab cua. Nws yog kev lag luam benchmark.
Xaiv C-22 thaum ntsib cov kev sib tw nyuaj tshaj plaws ntawm oxidizing thiab txo cov neeg ua haujlwm, lossis thaum lub siab tshaj plaws ua tau zoo tiv thaiv pitting thiab crevice corrosion nyob rau hauv chloride media yuav tsum tau muaj kev nyab xeeb los yog ntev, ua pov thawj nws tus nqi hwm.
2. Thaum ntsib qhov kev pabcuam hnyav, kub hydrochloric acid (HCl), vim li cas tus kws ua haujlwm tseem yuav xaiv C-276 lossis C-22 dhau ntawm nickel-molybdenum alloy zoo li Hastelloy B-2, thiab qhov kev lag luam tseem ceeb yog dab tsi?
Qhov no yog cov khoom siv classic xaiv qhov teeb meem ntawm qhov tshwj xeeb tiv thaiv kev tiv thaiv. Thaum Ni-Mo alloys (B- tsev neeg) yog qhov tsis sib xws rau cov ntshiab, kub HCl, tiag- cov txheej txheem ntiaj teb no tsis tshua muaj kev ntshiab.
Case rau C-276 / C-22 hauv HCl Kev Pabcuam:
Qhov kev txiav txim siab hinges ntawm lub xub ntiag ntawm oxidizing impurities los yog txheej txheem upsets. Txawm tias muaj pes tsawg tus oxidizing cov neeg ua hauj lwm -xws li yaj oxygen, ferric (Fe³⁺) los yog cupric (Cu²⁺) ions, nitric acid, los yog chlorine-kev puas tsuaj sai rau corrosion ntawm Ni-Mo alloys xws li B-2 los yog B-3. Cov alloys no vam khom ib puag ncig kom txo tau qhov passivity.
C-276 thiab C-22, nrog rau lawv cov ntsiab lus tseem ceeb ntawm chromium (16% thiab 22%), tuaj yeem tsim cov yeeb yaj kiab ruaj khov txawm tias nyob rau hauv cov xwm txheej oxidizing me ntsis. Yog li, lawv raug xaiv rau HCl kev pabcuam thaum:
HCl kwj yog paug (piv txwv li, pickling acids uas muaj hlau ions, khib nyiab acids los ntawm cov txheej txheem chlorination).
Muaj kev pheej hmoo ntawm huab cua nkag los yog tsis sib haum xeeb.
Cov txheej txheem cuam tshuam nrog kev hloov pauv lossis sib xyaw chemistry qhov twg cov kauj ruam oxidizing yuav tshwm sim.
Kev nyab xeeb thiab kev ntseeg siab yog qhov tseem ceeb; lub alloy muab ib qho "kev zam txim" tiv thaiv cov txheej txheem variability.
Kev lag luam tseem ceeb- tawm:
Corrosion Rate nyob rau hauv Ntshiab, Txo HCl: Nyob rau hauv kub, aerated, tab sis lwm yam ntshiab HCl, C-276 thiab C-22 yuav muaj ib tug ntsuas, thiab tej zaum tseem ceeb, corrosion tus nqi. B-2 / B-3 yuav ua tau zoo heev, feem ntau nrog zero corrosion. Siv C-276 / C-22 ntawm no yog overkill thiab technically inferior.
Tus nqi: C-22 kim dua li C-276 thiab B-2. Qhia rau nws kom txo tau cov kev pab cuam pov tseg peev.
Kev pheej hmoo ntawm Kev Tawm Tsam Hauv Zos: Yog tias ib puag ncig tau txo qis, cov ntsiab lus chromium siab tsis pab, thiab cov ntsiab lus qis molybdenum (vs. B-2) tuaj yeem dhau los ua lub luag haujlwm.
Tus engineer yuav tsum ua ib qho kev soj ntsuam nruj ntawm covtiag tiag, phem tshaj -casetxheej txheem chemistry, tsis yog qhov nominal "HCl kev pabcuam." Qhov kev xaiv sawv cev rau qhov sib npaug ntawm kev ua kom zoo rau qhov chaw kuaj mob zoo meej (B-2) thiab tiv thaiv kev sib txawv ntawm lub ntiaj teb tiag tiag thiab impurities (C-276/C-22).
3. Dab tsi yog qhov tseem ceeb tshaj plaws kev vuam thiab kev txiav txim siab tshwj xeeb rau C-22 uas sib txawv nws cov kev coj ua zoo tshaj plaws ntawm cov rau C-276?
Thaum ob qho tib si alloys yog tsim los rau weldability zoo heev thiab qhia cov hauv paus ntsiab lus (kev huv, tsis tshua muaj cua sov input, inert gas shielding), ua hauj lwm nrog C-22 xav tau ntau dua rau cov ntsiab lus vim nws kho chemistry.
Kev Sib Koom Hauv Kev Ua Haujlwm:
Kev huv huv tsis huv: Kev tshem tawm tag nrho cov organic residues, sulfur, thiab qis- melting- cov kab mob kis tsis tau yog - sib tham tau rau ob qho tib si.
Cov Khoom Siv Hluav Taws Xob Hluav Taws Xob: Siv GTAW (TIG) nrog cov hlaws dai kom txo tau cov cua sov-tshem tawm tsam (HAZ) thiab lub sijhawm nyob rau hauv qhov kev xav tau ntau.
Tag Nrho Inert Gas Shielding: Cov roj rov qab zoo (purge) thiab cov ntaub thaiv npog yog qhov tseem ceeb los tiv thaiv cov hlau molten weld los ntawm huab cua paug.
Cov Txheej Txheem Tseem Ceeb thiab Kev Ua Kom Zoo rau C-22:
Filler Metal Selection - Qhov "Tshaj -Matching" Philosophy:
Rau C-276, siv cov khoom sib txuam hlau (ERNiCrMo-4) yog tus qauv thiab siv tau.
Rau C-22, kev ua lag luam zoo tshaj plaws yog siv cov hlau muab tub lim uas "dhau- sib tw" lossis tsawg kawg yog qhov sib npaug ntawm lub hauv paus hlau tiv thaiv corrosion. Feem ntau, cov hlau muab tub lim tau teev rau vuam C-22 yog ERNiCrMo-10 (uas sib haum rau cov hlau 622 / C-22 muaj pes tsawg leeg) lossis txawm tias ERNiCrMo-14 (C-276). Lub laj thawj yog los xyuas kom meej cov hlau weld, uas muaj kev sib cais ntawm micro-segregation thaum lub sij hawm solidification, tuav ib tug corrosion kuj sib npaug los yog ntau tshaj tus niam txiv C-22 phaj. Kev siv cov khoom siv tsis zoo tuaj yeem tsim kom muaj galvanic cell.
Nco ntsoov Weld Hlau Chemistry & Ferrite Number (FN):
C-22's siab dua chromium thiab qis molybdenum tshuav nyiaj li cas tuaj yeem ua rau muaj qhov ua tiav ntawm austenitic weld microstructure, uas muaj kev cuam tshuam ntau dua rau kev sib tsoo (kub tawg) yog tias cov pas dej sib kis tshwm sim los yog kev txwv siab. Cov txheej txheem yog li hais txog:
Tighter tswj ntawm impurity ntsiab (S, P, Si, Pb) nyob rau hauv ob lub hauv paus thiab muab tub lim hlau.
Qee qhov tshwj xeeb yuav hu rau cov hlau muab tub lim nrog me me, tswj cov khoom ntxiv xws li Niobium (Nb) los txhawb kev tsim cov me me ntawm cov txiaj ntsig theem nrab uas "txuas" impurities thiab txo qhov kev sib tsoo, txawm tias qhov no tsis tshua muaj ntau dua li cov hlau tsis muaj steel.
Interpass Temperature Control:
Txawm hais tias tseem ceeb rau ob qho tib si, nws feem ntau tuav mus rau qhov txwv nruj dua rau C-22 (xws li,<250°F / 121°C) to manage overall thermal input and minimize the potential for deleterious phase formation, although C-22 is highly stable.
Hauv cov ntsiab lus, kev tsim C-22 yuav tsum muaj tib lub hauv paus kev qhuab qhia zoo li C-276 tab sis nrog kev ua kom pom tseeb ntawm cov hlau chemistry kev ncaj ncees kom paub txog nws cov kev ua tau zoo corrosion hauv cov khoom tiav.
4. Hauv Flue Gas Desulfurization (FGD) systems, vim li cas C-22 tau nce ntxiv rau thaj chaw tseem ceeb tshaj plaws xws li qhov hluav taws xob qhov hluav taws xob thiab cov pos huab tshem tawm lub taub hau, txawm tias C-276 muaj keeb kwm ua haujlwm ntev?
FGD ib puag ncig sawv cev rau "dhau cua daj cua dub" ntawm corrosion: qis pH, siab chlorides, fluorides, ya tshauv abrasion, kub cycling, thiab alternating oxidizing/txo tej yam kev mob. Kev hloov mus rau C-22 hauv cov chaw tseem ceeb yog tsav los ntawm kev txheeb xyuas tus nqi ntawm lub neej thiab nrhiav kev ntseeg siab tshaj plaws.
Kev txwv ntawm C-276 hauv Extreme FGD Cov Cai:
C-276 ua tau zoo heev, tab sis nyob rau hauv qhov hnyav tshaj plaws, thaj chaw hauv cheeb tsam, nws cov kev txwv tuaj yeem ncav cuag:
Qhov hluav taws xob cov kav dej & Reheaters: Cov cheeb tsam no tau kub, condensed acids nrog cov tshuaj chloride siab tshaj plaws thiab oxidizing tej yam kev mob los ntawm huab cua. Lub Critical Crevice Temperature (CCT) ntawm cov khoom yog qhov tseem ceeb. C-22 muaj qhov pom tau tias CCT siab dua C-276, muab qhov kev nyab xeeb ntau dua rau kev tiv thaiv kev xeb hauv kev rwb thaiv tsev, ntawm cov hlua txuas, lossis hauv qab tso nyiaj.
Mist Eliminator Wash Headers: Lawv raug cov tshuaj chlorinated acidic slurry tas li thiab ua rau txhaws thiab nyob rau hauv - deposit (crevice) corrosion. Qhov txhim kho hauv cheeb tsam corrosion kuj ntawm C-22 txo qhov kev pheej hmoo pitting.
Ntau cov tshuaj chloride Loads: Cov chaw tsim hluav taws xob niaj hnub no yuav ntsib cov roj ntau dua los yog siv cov tshuaj ntxuav dej hiav txwv, ua rau cov tshuaj chloride siab. C-22's optimized Cr / Mo / W tshuav nyiaj li cas muaj kev tiv thaiv zoo dua nyob rau hauv cov mob hnyav no.
Tus Tsav Tsheb: Tus Nqi Tag Nrho Cov Tswv Cuab (TCO)
Thaum C-22 phaj thiab yeeb nkab muaj tus nqi pib siab dua (CapEx) dua li C-276, kev suav nyiaj txiag rau lub tshuab fais fab hnyav qhov no tiv thaiv:
Kev ncua sij hawm ncua sij hawm: Hloov lub qhov hluav taws xob qhov hluav taws xob yog qhov kim kim thiab yuav tsum tau ncua sij hawm tawm. Kev qhia C-22 tuaj yeem txuas ntxiv lub neej kev pabcuam los ntawm, piv txwv li, 10 xyoo mus rau 20+ xyoo, txo cov nqi tu lub neej hauv ib nrab.
Kev Tiv Thaiv Kev Tsis Txaus Siab: Kev ua tsis tiav hauv qhov tseem ceeb FGD tivthaiv tuaj yeem yuam kom kaw lub boiler, raug nqi ntau pua txhiab daus las ib hnub hauv kev ploj tiam. C-22 cov npoo ntxiv txo qhov kev pheej hmoo no.
Kev ua tau zoo hauv cov xwm txheej ntxhov siab: Thaum cov nroj tsuag tsis txaus siab lossis sootblowing, cov xwm txheej tuaj yeem ua rau muaj kev txhoj puab heev. C-22 muab qhov tsis muaj zog dua.
Yog li ntawd, kev siv C-276 tseem muaj thoob plaws rau lub plhaub ntauwd thiab cov cheeb tsam tseem ceeb tsawg, tab sis muaj qhov kev lag luam pom tseeb los txhim kho qhov yooj yim tshaj plaws, crevice -nrhiav, thiab high-chloride zones mus rau C-22 raws li kev nqis peev hauv kev cog qoob loo thiab txo nqi lifecycle.
5. Rau cov tshuaj reactor tshiab uas tuav cov complex, multi-theem synthesis uas muaj halogenated cov kuab tshuaj, muaj zog acids, thiab alkaline ntxuav, dab tsi rational yuav txhawb kev qhia cov nqi kim tshaj C-22 tshaj C-276?
Qhov xwm txheej no sawv cev rau cov ntaub ntawv siv zoo tshaj plaws rau C-22, qhov twg nws qhov dav thiab muaj zog tiv thaiv profile ncaj qha rau kev ua haujlwm yooj yim, kev nyab xeeb, thiab kev txuag peev.
Lub hauv paus ntsiab lus tseem ceeb yog kev tiv thaiv rau lub hnab ntawv dav dav ntawm cov tshuaj lom neeg thiab kev ntxhov siab, thiab kev ua haujlwm zoo tshaj plaws hauv kev txhoj puab heev, hauv zos corrosion scenarios.
Kev Sib xyaw thiab Hloov Cov Tshuaj: Ntau- cov txheej txheem batch feem ntau suav nrog kev ntxuav (NaOH ntxuav), acidifications (HCl, H₂SO₄), thiab cov tshuaj tiv thaiv nrog halogenated intermediates (uas tuaj yeem hydrolyze los ua HCl). Ib puag ncig ncig los ntawm kev txo qis rau oxidizing. C-22 cov ntsiab lus chromium siab dua muab kev ua tau zoo dua thaum lub sij hawm oxidizing cov kauj ruam (xws li, nitric acid ntxuav tawm) thiab nyob rau hauv lub xub ntiag ntawm tej oxidizing halogen byproducts, thaum tseem tuav tau zoo heev tiv thaiv kom txhob acid cov kauj ruam. Nws yog ntau "kev zam txim" cov ntaub ntawv rau txheej txheem variability.
Superior Localized Corrosion Resistance nyob rau hauv Halogenated Systems: Halogenated cov kuab tshuaj thiab lawv cov khoom tawg (chlorides, bromides) tsis zoo rau kev ua rau pitting thiab crevice corrosion, tshwj xeeb tshaj yog nyob rau hauv vapor qhov chaw thiab hauv qab deposits. C-22's siab dua Chromium thiab optimized Tungsten cov ntsiab lus muab nws ntau dua Pitting Resistance Equivalent Number (PREN) thiab siab dua qhov kev sim ntsuas CPT/CCT qhov tseem ceeb tshaj C-276. Qhov no yog qhov tseem ceeb rau reactor nozzles, agitator seals, thiab baffle txuas cov ntsiab lus-cov cheeb tsam uas muaj crevices.
Kev Tiv Thaiv Cov Txheej Txheem Txheej Txheem: Cov kab hlau rhuav tshem cov khoom siv hluav taws xob (xws li hlau, tooj liab ntsev) tuaj yeem ua cov tshuaj oxidizing. C-22 muaj peev xwm tiv taus ntau dua thaum muaj cov kab mob no, uas tuaj yeem ua kom nrawm nrawm rau C-276.
Ntev- Lub Sij Hawm Stability thiab Cov Khoom Muaj nqis: Qhia C-22 rau ib qho khoom muaj nqis siab - zoo li lub reactor yog ib qho kev nqis peev hauv nws lub sijhawm ntev - kev ncaj ncees. Nws txo qhov kev pheej hmoo ntawm kev ua tsis tiav ntxov, ncua sij hawm nruab nrab ntawm kev tshuaj ntsuam xyuas, thiab tswj cov reactor tus nqi rau yav tom ntej, muaj peev xwm sib txawv, txheej txheem. Lub neej yav tom ntej no - pov thawj tuaj yeem yog qhov txiaj ntsig zoo hauv kev siv tshuaj ntau lub hom phiaj lossis cov nroj tsuag tshuaj zoo.
Hauv kev xaus, rau qhov yooj yim, zoo-txhais tau, cov txheej txheem tas mus li, C-276 qhov kev ua tau zoo yuav txaus thiab txuag nyiaj ntau dua. Txawm li cas los xij, rau qhov nyuaj, ntau yam - chemistry, tus nqi siab reactor qhov twg cov txheej txheem hloov pauv, kev ntxhov siab, thiab kev nyab xeeb siab tshaj plaws tau cia siab, qhov zoo tshaj plaws ntawm C-22 ua pov thawj nws tus nqi hwm. Nws ua raws li kev tuav pov hwm txoj cai tiv thaiv tus nqi loj uas cuam tshuam nrog lub reactor tsis ua haujlwm, cov khoom sib kis, thiab cov khoom siv tsis tau npaj tseg.
