Txias lub turbine condensers nyob rau hauv ib tug ntug dej hiav txwv fais fab nroj tsuag feem ntau muaj ib tug thib ob voj ntawm kho seawater los tiv thaiv biofouling thiab corrosion. Cov khoom siv hluav taws xob sib txuas hauv cov voj voog no yuav tsum tswj cov dej hiav txwv sov me ntsis nyob rau hauv siab, thiab duplex stainless hlau tau tshwm sim los ua cov khoom siv zoo, tus nqi zoo uas ua tau zoo tshaj 316L thiab sib tw nrog titanium.Duplex stainless hlau tshav kub exchanger seawater txiasdaim ntawv thov tau dhau los ua cov qauv kev daws teeb meem hauv kev tsim hluav taws xob hauv ntug dej hiav txwv, ntsuas kev tiv thaiv corrosion, txhua yam muaj zog, thiab tus nqi nyiaj txiag.
Lub luag haujlwm ntawm Cov Hluav Taws Xob Hluav Taws Xob hauv Seawater Cooling Loops
Nyob rau hauv ib tug raug dej hiav txwv fais fab nroj tsuag, raw seawater yog siv ncaj qha los yog indirectly kom txias lub condenser ntawm chav turbine. Cov dej hiav txwv ncaj nraim yog qhov ua tau zoo tab sis ua rau muaj kev pheej hmoo ntawm biofouling (mussels, barnacles, algae) thiab corrosion. Ntau cov nroj tsuag siv lub voj thib ob: kho lossis cov dej hiav txwv chlorinated circulates los ntawm lub tshav kub exchanger, txias lub voj dej tshiab los yog lwm cov kua dej, uas tom qab ntawd mus rau lub condenser. Lub tshav kub exchanger nyob rau hauv lub voj voog thib ob yuav tsum tiv taus qhov sov sov (feem ntau 30-45 degree), kho dej hiav txwv hauv qab siab.
Cov kev teeb tsa feem ntau yog lub plhaub-thiab-lub raj cua kub sib hloov, nrog cov dej hiav txwv ntws los ntawm cov hlab thiab cov turbine condenser txias dej ntawm lub plhaub sab, los yog vice versa. Cov khoom siv raj yuav tsum tiv taus cov tshuaj chloride pitting, crevice corrosion, thiab yaig los ntawm cov dej nrawm (2-3 m / s) xav tau kom cov raj huv si.
Yog vim li cas Duplex Stainless hlau yog nyiam
Ntau cov ntaub ntawv tau siv rau seawater heat exchangers:
Copper-nickel alloys (90/10 lossis 70/30)- Zoo corrosion kuj tab sis raug rau yaig thiab ammonia nres; kuj raug nqi thiab hnyav.
316L stainless hlau- Tsim nyog nyob rau hauv cov dej huv huv, oxygenated seawater tab sis muaj kev cuam tshuam rau chloride stress corrosion cracking (SCC) thiab pitting ntawm qhov kub siab tshaj 40 degree. Ntau cov nroj tsuag tau ntsib kev ua tsis tiav ntxov ntawm 316L hlab.
Titanium (Qib 2)- Zoo heev corrosion kuj nyob rau hauv dej hiav txwv, tsis tshua muaj kev pheej hmoo ntawm pitting los yog SCC. Txawm li cas los xij, titanium yog kim, yuav tsum tau tshwj xeeb fabrication, thiab muaj thermal conductivity tsawg.
Duplex 2205 (UNS S32205)- Muaj kev sib xyaw ua ke ntawm lub zog siab, zoo heev tiv thaiv chloride pitting thiab crevice corrosion, thiab tus nqi qis dua titanium. Nws tau dhau los ua qhov chaw qab zib rau ntau lub luag haujlwm dej hiav txwv uas titanium dhau-engineered thiab 316L tsis ua haujlwm.
Lub siab chromium (22%), molybdenum (3%), thiab nitrogen (0.15%) cov ntsiab lus ntawm duplex 2205 muab qhov sib npaug ntawm pitting tus lej (PREN) ntawm Ntau dua lossis sib npaug rau 35, ua rau nws tiv taus pitting txawm nyob hauv dej sov, chloride-nplua nuj seawater. Lub dual-phase microstructure (austenite thiab ferrite) kuj muab nws lub zog tawm los kwv yees li ob npaug ntawm 316L (450 MPa vs . 170 MPa). Qhov no tso cai rau cov phab ntsa hauv lub raj kom nyias nyias rau tib lub siab ntsuas, txo cov khoom siv, qhov hnyav, thiab tus nqi.
Qhov Zoo Tshaj Plaws Tshaj 316L thiab Titanium
Piv rau 316L
Chloride SCC kuj- Duplex 2205 yog qhov zoo tshaj plaws tiv thaiv chloride kev ntxhov siab corrosion tawg ntawm cov dej hiav txwv ua haujlwm kub (txog 60-80 degree), hos 316L tsis siab tshaj ~ 50 degree.
Siab dua tso cai- Cov phab ntsa nyias nyias tuaj yeem siv tau, txo qhov hnyav ntawm kev sib hloov thiab ua kom thermal efficiency (tsawg dua hlau tsis kam).
Zoo dua erosion kuj- Qhov siab dua hardness thiab lub zog ntawm duplex tiv thaiv impingement nres los ntawm cov xuab zeb lossis cov khib nyiab tshem tawm.
Lub neej ua haujlwm ntev dua- Ntau 316L seawater exchangers yuav tsum tau hloov tom qab 5-10 xyoo; chav tsev duplex tau ua tiav 20+ xyoo nrog kev ua haujlwm kom raug.
Piv rau Titanium
Cov khoom siv qis dua- Duplex 2205 tus nqi kwv yees li ib feem peb mus rau ib nrab tus nqi ntawm Qib 2 titanium ib kilogram.
Kev tsim tau yooj yim dua- Titanium xav tau kev tiv thaiv huab cua nruj thaum lub sijhawm vuam (siab purity argon rov qab-purge) thiab ua rau hydrogen embrittlement. Duplex tuaj yeem welded nrog tus qauv inert gas shielding, txawm tias nrog ceev faj tswj cov cua sov.
Siab thermal conductivity- Duplex (≈15 W / m·K) ua kom sov zoo dua titanium (≈7 W / m·K), tso cai rau thaj chaw me me sib hloov.
Tseem heev corrosion kuj- Rau kev kho kom zoo, ntws dej hiav txwv, duplex muab ntau tshaj li kev tiv thaiv txaus. Titanium yog tshwj tseg rau cov mob hnyav tshaj plaws (xws li, dej hiav txwv stagnation, kub siab heev, lossis cov ntawv thov uas muaj kev pheej hmoo ntawm kev ua tsis tiav).
Kev tsim thiab kev txiav txim siab ua haujlwm
Tube Phab Ntsa Thickness thiab Velocity
Vim hais tias ntawm duplex lub zog siab, ib txwm raj phab ntsa thicknesses rau seawater tshav kub exchangers yog 0.7-1.0 hli rau raj diameters ntawm 19-25 hli, piv rau 1.2-1.6 hli rau 316L. Cov phab ntsa thinner txo cov thermal tsis kam thiab ua rau kom siab dua tag nrho cov tshav kub hloov coefficient.
Seawater velocities los ntawm duplex tubes yuav tsum tau khaws cia siab tshaj 1.5 m / s los tiv thaiv sedimentation thiab biofouling, thiab qis dua li ntawm 3.5 m / s kom tsis txhob yaig-corrosion. Qhov tseem ceeb tshaj tawm rau duplex hauv dej hiav txwv huv yog siab dua rau 316L, muab lub qhov rais dav dua kev nyab xeeb.
Biofouling Control
Txawm tias muaj ob lub raj, biofouling (qhov txuas ntawm cov kab mob hauv hiav txwv) tuaj yeem tshwm sim. Lub biofilm lossis barnacle crust tsim cov cheeb tsam nyob ruaj khov nyob rau hauv qhov tso nyiaj, uas tuaj yeem ua rau qis qis qis thiab pitting. Txhawm rau tiv thaiv qhov no, cov dej hiav txwv feem ntau yog chlorinated (txawm tsis tu ncua lossis ntu ntu) mus rau qib chlorine seem ntawm 0.1-0.5 ppm. Duplex resists chlorine-accelerated corrosion zoo, yog tias cov concentration yog khaws cia hauv qhov txwv. Qee cov nroj tsuag kuj siv daim txhuam cev-pob tu tshuab los yog rov qab ntxuav txhua lub sijhawm.
Fabrication Note: Tswj vuam cua sov input
Duplex stainless hlau yuav tsum tau ceev faj welding kom ruaj khov austenite-ferrite microstructure. Kev siv hluav taws xob ntau dhau (siab dhau amperage lossis qeeb mus ncig ceev) tuaj yeem ua rau muaj kev cuam tshuam ntawm intermetallic theem, xws li theem sigma, uas ua rau txo qis corrosion thiab toughness. Vuam yuav tsum tau ua nrog lub tshav kub input ntawm 0.5-1.5 kJ / mm, siv cov muab tub lim sib txuam (xws li, 2209). Post-weld pickling lossis electropolishing yog qhov tseem ceeb kom tshem tawm cov cua sov (oxide discoloration) thiab rov ua dua cov txheej txheem chromium oxide passive. Unpickled weld aav yog qhov yooj yim rau kev nyiam corrosion hauv dej hiav txwv thiab yuav tsum zam.
Fabrication thiab Quality Assurance
Ntxiv nrog rau kev tswj vuam, cov kev coj ua hauv qab no yog tus qauv rau duplex seawater heat exchangers:
Kev ntsuam xyuas hydrostatic- Siv dej tshiab nrog cov tshuaj chloride tswj (<50 ppm) to avoid pitting during the test.
Ferrite ntsuas- Lub vuam hlau thiab thaj chaw muaj kev kub ntxhov yuav tsum muaj 30-60% ferrite, ntsuas los ntawm ferritescope, kom ntseeg tau tias muaj kev tiv thaiv corrosion.
Passivation- Tom qab fabrication, lub exchanger yog chemically passivated (piv txwv li, nrog citric los yog nitric acid) kom ua kom cov zaj duab xis passive.
Tube-rau-tubesheet welding- Ib qho kev nkag mus rau tag nrho yog qhov zoo dua, nrog rau cov tubesheet kuj ua los ntawm duplex (los yog duplex weld overlay ntawm carbon steel kom txo nqi).
Kev paub txog kev ua haujlwm hauv Coastal Power Plants
Ntau lub chaw tsim hluav taws xob hauv ntug dej hiav txwv hauv Tebchaws Europe, North America, thiab Asia tau ua tiav kev xa tawm duplex stainless hlau tshav kub exchangers rau seawater txias circuits. Piv txwv li, nyob rau hauv lub tebchaws United Kingdom, ntau lub chaw nres tsheb roj hluav taws xob siv 2205 lub raj ntim hauv lawv cov dej txias txias. Nyob rau hauv Singapore, cogeneration cog hloov ua tsis tiav 316L txias txias nrog duplex units, ua tiav 15 xyoo ntawm kev ua haujlwm tsis muaj teeb meem nrog kev tshuaj xyuas txhua xyoo qhia tias tsis muaj pitting lossis tawg.
Qhov tsuas yog tshaj tawm tsis ua tiav tau taug qab mus rau ib qho:
Kev siv vuam tsis zoo (ntau dhau ntawm cov txheej txheem intermetallic vim muaj cua sov nkag).
Pickling tsis txaus (tawm tshav kub tint, uas ces corroded preferentially).
Kev nthuav dav ntxiv rau cov dej hiav txwv uas tsis muaj tshuaj chlorinated (xws li, thaum lub sijhawm kaw ntev) ua rau biofouling thiab qis qis qis.
Thaum tsim thiab ua haujlwm zoo, cov khoom siv hluav taws xob duplex tau ua pov thawj tias yog ib qho kev ntseeg siab, nyob ntev.
Nqi-Benefit Analysis
Rau ib tug loj loj plhaub-thiab-tube exchanger ntawm 500 m² cheeb tsam:
316l kev- Tus nqi pib qis tshaj plaws tab sis yuav tsum tau hloov txhua 5-10 xyoo. Cov nqi poob qis thiab kev pheej hmoo ntawm kev ua tsis tiav yog qhov siab.
Titanium kev xaiv- Tus nqi pib siab tshaj plaws (2–3 × ntawm duplex), tab sis lub neej ntev heev (30+ xyoo). Tej zaum yuav muaj kev ncaj ncees yog tias tus pauv pauv nyob rau hauv qhov chaw tseem ceeb, nyuaj hloov qhov chaw.
Duplex xaiv- Tus nqi pib kwv yees li 1.3-1.5 × ntawm 316L tab sis 0.5 × ntawm titanium. Nrog lub neej tsim ntawm 20-25 xyoo, nws muaj qhov zoo tshaj plaws lifecycle tus nqi rau feem ntau seawater txias dej.
Hauv kev tsim hluav taws xob, kev ntseeg siab yog qhov tseem ceeb. Lub peev xwm los khiav lub duplex exchanger rau ob xyoo lawm yam tsis muaj raj tsis ua hauj lwm los yog phab ntsa thinning tau ua rau nws nyiam xaiv rau cov nroj tsuag tshiab thiab rau retrofits.
Xaus
Duplex stainless hlau tshav kub exchangers tau dhau los ua ib qho kev daws teeb meem hauv kev tsim hluav taws xob hauv ntug dej hiav txwv, xa qhov sib npaug ntawm kev tiv thaiv corrosion, txhua yam muaj zog, thiab kev lag luam tus nqi. Rauduplex stainless hlau tshav kub exchanger seawater txiasDaim ntawv thov, Qib 2205 muab kev tiv thaiv zoo heev rau cov tshuaj chloride pitting thiab crevice corrosion, ua ke nrog lub zog tawm los uas tso cai rau cov phab ntsa nyias nyias, txo qhov hnyav, thiab txhim kho thermal ua haujlwm. Thaum 316L raug kev txom nyem los ntawm kev ntxhov siab tawg hauv dej hiav txwv sov, thiab titanium tseem raug nqi txwv rau ntau txoj haujlwm, duplex occupies qhov zoo nruab nrab hauv av. Nrog ceev faj welding, post-weld pickling, thiab tswj biofouling kom zoo, cov exchangers xa tau 20+ xyoo ntawm kev pab cuam txhim khu kev qha. Kev xaiv cov hlau zoo ib txhij tuaj yeem txo cov khoom siv thiab txuas ntxiv lub neej ntawm cov nroj tsuag -ib txoj hauv kev uas duplex stainless hlau ua pov thawj hauv txhua qhov chaw cog hluav taws xob ntug dej hiav txwv uas nws tau teev tseg.
