FGD System Cov Khoom Siv Xaiv: Nplai Gas Desulfurization

Dab tsi yog Flue Gas Desulfurization (FGD)?

Flue Gas Desulfurization (FGD) yog cov txheej txheem kev lag luam uas siv los tshem cov sulfur dioxide (SO2) - thiab tsawg dua hydrogen chloride (HCl) thiab hydrogen fluoride (HF) - los ntawm cov pa roj carbon monoxide - tua hluav taws xob, smelters, cement kilners, thiab cov khib nyiab pov tseg rau hauv qhov chaw ua ntej.

SO2 yog thawj qhov ua rau cov kua qaub los nag, uas ua rau puas tsuaj rau ecosystems, corrodes infrastructure, thiab ua phem rau tib neeg txoj kev ua pa. Cov kev cai thoob ntiaj teb - suav nrog US Clean Air Act, EU Industrial Emissions Directive (IED 2010/75/EU), thiab Tuam Tshoj's GB 13271 emission standard - mandate SO2 removalefficients over 95% for most combustion installations.

Qhov tseem ceeb FGD thev naus laus zis thoob ntiaj teb yogntub limestone yuam oxidation (WLFO), uas suav txog kwv yees li 85% ntawm kev teeb tsa FGD muaj peev xwm thoob ntiaj teb. Hauv WLFO qhov system, cov pa roj flue raug hu nrog cov limestone (CaCO3) slurry hauv lub nkoj loj absorber. Lub SO2 reacts nrog cov slurry los tsim calcium sulfate (gypsum, CaSO4·2H2O) - muag muag los ntawm - khoom siv nyob rau hauv wallboard manufacturing.

Vim li cas FGD Destroys Ordinary Steel

FGD systems yog ib qho ntawm cov kev lag luam corrosive tshaj plaws hauv ntiaj teb. Kev sib xyaw ua ke ntawm cov khoom hauv cov ntaub ntub dej tsim cov tshuaj lom neeg ib puag ncig uas rhuav tshem cov hlau tsis pub dhau lub hlis thiab tawm tsam txawm tias tus qauv stainless hlau:

Chloride concentration:Chloride ions (Cl⁻) - tso tawm los ntawm thee combustion thiab concentrated los ntawm cov txheej txheem txhuam - nyob rau hauv lub absorber recirculating kua mus rau theem ntawm 20,000-100,000 ppm. Nyob rau hauv cov concentrations no, chlorides nkag mus rau passive oxide txheej ntawm cov qauv stainless hlau, pib pitting thiab crevice corrosion.

Acid pH:Lub absorber slurry ua haujlwm ntawm pH 3-6, nthuav tawm txhua qhov chaw ntub dej kom dilute sulfuric thiab sulfurous acid tsis tu ncua.

Kub caij tsheb kauj vab:Cov kav dej muaj kev cuam tshuam txog kev sib tw ntawm 50℃(qhov hluav taws xob ntub dej) thiab 200℃(pre-scrubber inlet), ua rau muaj kev ntxhov siab rau ob qho tib si hauv cov ntaub ntawv thiab cov txheej txheem hauv ob sab phlu.

Kev yaig:Limestone slurry recirculated ntawm 3-8 m / s los ntawm cov twj, piping, thiab tshuaj tsuag nozzles ua rau hnyav erosive hnav, uas synergizes nrog corrosion kom ceev cov khoom poob.

Stress Corrosion Cracking (SCC):Tensile stress nyob rau hauv welds thiab structural tswv cuab, ua ke nrog kub chloride -muaj kua, ua rau SCC nyob rau hauv austenitic stainless hlau nrog PREN hauv qab no ~ 40.

Cov ntaub ntawv kev lag luam:A 600 MW thee- hluav taws xob cog FGD txheej txheem txheej txheem kwv yees li 2–3 lab Nm³ / hr ntawm flue gas. Cov hlab ntsha hauv WLFO feem ntau ntsuas 15-25 m hauv txoj kab uas hla thiab 20-30 m siab - ua cov khoom xaiv rau lub plhaub liner thiab sab hauv ntau - lab daus las txiav txim siab nrog 30-xyoo tsim lub neej expectancy.

FGD Zone Conditions Summary

Table 1: Corrosive Conditions los ntawm FGD System Zone

Pom zoo Alloys los ntawm FGD Component

Tsis muaj ib qho alloy yog qhov zoo rau txhua cheeb tsam ntawm FGD system. Kev xaiv cov khoom siv raug yog qhov sib txuam ntawm cov alloy qhov corrosion kuj - ntsuas ntau los ntawm nws cov Pitting Resistance Equivalent Number (PREN=%Cr + 3.3 ×% Mo + 16×%N) - rau qhov tshwj xeeb chloride concentration, pH, kub, thiab mechanical loading ntawm txhua qhov system.

Table 2: Pom zoo Alloys los ntawm FGD Component thiab kev ua haujlwm

Ntsiab Alloy Properties Reference

Table 3: Chemical Composition thiab PREN ntawm FGD Alloys|* PREN=%Cr + 3.3×%Mo + 16×%N

Alloy C276 - FGD Benchmark

Hastelloy C276 (UNS N10276)yog qhov dav tshaj plaws uas tau teev tseg rau FGD lub luag haujlwm hnyav. Nws cov ntsiab lus molybdenum ntawm 15-17% - qhov siab tshaj plaws ntawm cov khoom lag luam tsim cov nickel alloy - muab nws PREN ntawm kwv yees li 65 thiab ua haujlwm zoo rau ob qho tib si oxidizing thiab txo cov kua qaub ib puag ncig. C-276 yog teev rau absorber plhaub nyob rau hauv siab -chloride WLFO systems, ntub pawg liners, thiab raws li 2-3 hli wallpaper cladding ntawm carbon steel duct substrates. Nws tau ua raws li ASME Tshooj VIII siab lub nkoj tsim thiab tuaj yeem ua orbital-welded siv txuam ERNiCrMo-4 muab tub lim hlau.

Alloy 625 - Erosion-Tus Kws Tshaj Lij Choj

Alloy 625 (N06625)ua ke nrog cov chromium siab (20–23%), molybdenum (8–10%), thiab niobium ntxiv uas muab nws tshwj xeeb rau kev yaig-corrosion - sib xyaw ua ke ntawm cov khoom abrasive thiab corrosive media uas rhuav tshem cov tshuaj tsuag thiab cov twj tso kua mis sab hauv. Nws PREN ntawm kwv yees li 51 thiab lub zog tensile siab (827-1034 MPa) ua rau nws qhov kev xaiv zoo tshaj plaws rau FGD tshuaj tsuag headers, pos huab eliminators, thiab recirculation twj impellers qhov twg slurry tshaj tawm tshaj 4 m / s.

317LMN - Tus Nqi-Nyob Nruab Nrab Nruab Nrab

Qib 317LMN (S31726) - ib qho kev txhim kho ntawm 317L nrog molybdenum ntawm 4-5% thiab tswj cov nitrogen ntxiv - ua tiav PREN ntawm kwv yees li 40 ntawm tus nqi qis dua cov nickel alloys. Nws yog dav siv rau FGD absorber shells nyob rau hauv nruab nrab- daim ntaub ntawv lub luag hauj lwm qhov twg chloride concentrations qis dua 30,000 ppm thiab pH nyob saum 4. Nws sawv cev rau tus nqi tshaj plaws -txheej txheem austenitic stainless xaiv rau tshiab FGD kev tsim kho qhov twg C-276 tsis tuaj yeem tsim nyog rau kev lag luam.

Cladding thiab hauv ob sab phlu: Muab lub zog nrog corrosion kuj

Rau loj - txoj kab uas hla FGD absorber hlab ntsha thiab ducts, siv cov khoom C-276 phaj yog nqi- txwv tsis pub. Kev lag luam kev daws teeb meem yog kev tsim kho: carbon steel lossis low-alloy steel plhaub muab cov qauv muaj zog, thaum lub nyias nyias txheej muab kev tiv thaiv corrosion:

Wallpaper cladding (weld overlay):2–3 mm C-276 siv los ntawm sawb cladding los yog automated weld overlay rau carbon steel sab hauv. Tus nqi -zoo rau loj- cheeb tsam kev pab them nqi; lub overlay yuav tsum ua kom tiav qhov tsawg kawg yog ob -thov tso nyiaj kom paub meej tias cov khoom sib xyaw ua kom raug raws li PREN cov cai.

Explosion-bonded clad phaj:Factory-tsim C-276/carbon steel clad phaj, fabricated rau hauv lub nkoj plhaub. Muab qhov tseeb, zoo ib yam alloy thickness (feem ntau 3-5 hli); nyiam rau cov hlab ntsha absorber xav tau ASME code stamp.

Loose alloy liners:Nyias (1.5–2 mm) C-276 los yog 625 nplooj ntawv kho kho los yog adhesively bonded rau carbon steel ducts. Teb-installable; siv nyob rau hauv retrofit tej yaam num uas kub-ua hauj lwm yog txwv.

Kev Paub Txog Tus Nqi:Khoom C-276 phaj nqi kwv yees li 8–12 × tus nqi ntawm cov hlau los ntawm qhov hnyav. Phab ntsa cladding txo cov ntsiab lus alloy rau 15-25% ntawm cov nqi tsim kho khoom thaum xa cov kev tiv thaiv corrosion sib npaug ntawm qhov chaw ntub dej - ua rau nws tus qauv kev daws teeb meem rau FGD absorber hlab ntsha tshaj 10 m txoj kab uas hla.

Fabrication thiab Quality Requirements

Vuam muab tub lim:C276 require ERNiCrMo-4 filler (AWS A5.14); Alloy 625 siv ERNiCrMo-3; 317LMN siv ER317L lossis zuag qhia tag nrho 309LMo. Kev sib txuam lossis cov khoom siv ntau dhau los tiv thaiv kev sib tsoo hlau los ntawm kev txo PREN hauv qab qib hlau.

Thaum tshav kub kub tint tswj:Nickel alloy welds yuav tsum rov qab -purged nrog 99.995% ntshiab argon tiv thaiv oxide tsim ntawm cov hlaws hauv paus. Thaum tshav kub kub tint ntawm C-276 welds qhia tau hais tias lub zos molybdenum depletion thiab yuav tsum tau muab tshem tawm los ntawm pickling los yog mechanical finishing.

Ncej -welding kev kho mob:Nickel alloys tsis xav tau tom qab-weld heat treatment (PWHT) thiab degraded los ntawm nws (sigma theem nag lossis daus). 317LMN welds hauv FGD cov kev pabcuam feem ntau yog kev daws teeb meem-annealed yog tias muaj kev txhawj xeeb.

Kev tshuaj xyuas:100% radiographic (RT) los yog ultrasonic (UT) kuaj ntawm tag nrho cov siab-muaj welds nyob rau hauv absorber hlab ntsha; dye penetrant (PT) kuaj ntawm tag nrho C-276 weld overlays kom paub meej tias kev ywj pheej ntawm cov kab nrib pleb thiab tsis muaj fusion.

Cov qauv siv tau

ASTM B575 / B622 - C-276 thiab C-22 phaj, ntawv, sawb, thiab yeeb nkab

ASTM B443 / B444 - Alloy 625 phaj thiab yeeb nkab

ASTM A240 - 316L, 317L, 317LMN stainless hlau tiaj tus- cov khoom dov

ASME Seem VIII Div. 1 - Pressure vessel fabrication (absorber vessels)

NACE MR0103 - Cov ntaub ntawv tiv taus sulfide kev nyuaj siab tawg hauv qhov chaw qaub refinery

ISO 9001 / EN 10204 Hom 3.1 - Cov ntaub ntawv pov thawj thiab traceability rau FGD kev tsim kho

Xaus

Kev xaiv cov khoom siv yog qhov kev txiav txim siab engineering tshaj plaws hauv FGD qhov system tsim. Kev qhia txog txoj cai alloy - sib phim rau cov tshuaj chloride concentration, pH, kub, thiab mechanical loading ntawm txhua qhov system cheeb tsam - yog qhov sib txawv ntawm 30-xyoo kev pab cuam lub neej thiab kim tsis ua hauj lwm ntxov ntxov.

Lub hierarchy yog tseeb:use 316L/317L where chloride levels are low and pH is moderate; upgrade to 317LMN or 6Mo stainless where chloride concentrations reach 20,000–50,000 ppm; specify Alloy 625 where erosion-corrosion combines with aggressive chemistry; and deploy Alloy C-276 (solid or clad) wherever continuous exposure to >50,000 ppm chloride, pH<4, or wet stack conditions demands maximum corrosion performance.

Raws li kev tswj hwm ib puag ncig nruj nruj thoob ntiaj teb thiab cov khoom siv tau nqis peev hauv kev rov tsim kho cov hluav taws xob laus nrog FGD cov tshuab, qhov kev thov rau daim ntawv thov -matched, code- ua raws qib siab - alloys kev ua tau zoo yuav loj tuaj. Tau txais cov ntaub ntawv tshwj xeeb nyob rau theem tsim yog tus nqi tshaj plaws - kev nqis peev zoo hauv FGD kev ntseeg tau.