Yuav ua li cas Desalination Nroj Tsuag Ua Haujlwm
Ib tsob nroj desalination tshem tawm cov ntsev yaj ntawm dej hiav txwv los tsim cov dej tshiab. Ob lub thev naus laus zis tseem ceeb: Cov txheej txheem cua sov (MSF thiab MED) thiab cov txheej txheem Membrane (SWRO). Txhua tus txheej txheem muaj qhov sib txawv corrosion ib puag ncig uas xav tau qib stainless hlau sib txawv.
Thermal Desalination: MSF thiab MED
Multi-Stage Flash (MSF) thiab Multi-Effect Distillation (MED) cov nroj tsuag ua haujlwm ntawm tib lub hauv paus ntsiab lus: dej hiav txwv yog cua sov, ib nrab evaporates, thiab cov vapor yog condensed li dej tshiab. Qhov txawv yog tias MSF siv cov chav ua haujlwm siab (theem) ntawm qhov txo qis, thaum MED siv ntau yam teebmeem (vasour los ntawm ib qho txiaj ntsig yog siv los ua qhov nruab nrab cua sov rau tom ntej).
MSF cov nroj tsuag feem ntau ua haujlwm nrog qhov kub siab tshaj plaws (TBT) ntawm 90C-120C. MED cov nroj tsuag ua haujlwm ntawm qhov kub qis (60C-90C rau ib qho txiaj ntsig), uas yog vim li cas MED feem ntau tsis muaj corrosive dua li MSF.
Membrane Desalination: SWRO
Seawater Reverse Osmosis (SWRO) ua haujlwm los ntawm kev siv siab siab (55-80 bar) rau cov dej hiav txwv hla ib nrab -permeable membrane. Lub membrane tsis lees txais ntsev; cov concentrate (brine, ~ 70-80 g / L TDS) yog tawm ntawm lub siab. SWRO muaj zog ntau dua li cov txheej txheem thermal thiab tam sim no suav rau feem ntau ntawm cov peev txheej tshiab desalination thoob ntiaj teb.
Table 1: Desalination Technologies - Txheej Txheem Sib Piv thiab Corrosion Relevance
| Txheej txheem | Txoj Cai | Hom Loj | Kev siv hluav taws xob | Sab saum toj Brine Temp (C) | Tus naj npawb ntawm cov nroj tsuag thoob ntiaj teb |
MSF (Multi{0}}Stage Flash)
| Evaporation + flash distillation nyob rau hauv theem theem
| 10-75 MDL
| 8-14 kWh/m3 (kwv yees + hluav taws xob)
| 90-120
| ~ 350 (tsis kam)
|
MED (Ntau -Cov nyhuv Distillation)
| Evaporation hla ntau yam teebmeem; vapor rov siv dua
| 10-75 MDL
| 5-10 kWh/m3 (kub + hluav taws xob)
| 60-90
| ~ 200 (ruaj khov)
|
SWRO (Seawater RO)
| High -siab membrane filtration
| 1-500 MDL
| 3-5 kWh/m3 (tsuas yog hluav taws xob)
| Ambient (~25C)
| ~ 17,000 (loj hlob sai)
|
FO-MED (hybrid)
| Forward Osmosis + MED hybrid
| 5-30 MDL
| 2-4 kWh/m3
| < 40
| ~ 10 (thaum ntxov)
|
Sludge (Zero Liquid Discharge)
| Brine crystallisation + evaporation
| Qhov project- tshwj xeeb
| 10-20 kWh/m3
| Hloov pauv
| ~ 50 (tawm)
|
Tsib Corrosion Zones nyob rau hauv ib tsob nroj Desalination
Txhua tsob nroj desalination tuaj yeem muab faib ua tsib thaj chaw sib txawv, txhua tus muaj cov txheej txheem sib txawv thiab cov kev xav tau ntawm stainless hlau sib txawv.
Table 2: Lub Six Corrosion Zones hauv Desalination Cog - Qhov tseem ceeb Parameters
| Zone | Qhov chaw | Kub (C) | Chloride (ppm) | Cov pa oxygen (ppm) | Flow Velocity | Kev Ua Haujlwm Microbiolog | Pitting Risk |
Zone 1: Kev nkag
| Raw seawater intake qhov, cov ntxaij vab tshaus, twj tso kua mis
| 20-32
| 18,000-22,000
| 4-8
| 1-3m / s (tsawg)
| High (Biofilm)
| Nruab nrab (316L OK)
|
Zone 2: Pre-kev kho mob
| Cartridge lim, flocculation tank, dosing ntsiab lus
| 25-35
| 18,000-22,000
| 6-10
| 1-3 m/s
| Siab heev
| Siab (316L marginal)
|
Thaj Chaw 3: Siab -Txoj Haujlwm Siab
| SWRO: HP twj tso kua mis manifold, concentrate piping (55-80 bar)
| 25-40
| 25,000-35,000 (kuj)
| < 2 (deoxygenated)
| Siab (3-5m / s)
| Tsawg (dej huv)
| Siab heev (SS muaj kev pheej hmoo)
|
Zone 4: Membrane Tsheb ciav hlau
| SWRO: siab hlab ntsha, membrane ntsiab, khoom dej
| 20-30
| < 500 (product water)
| < 0.1 (deoxygenated)
| Tsawg (membrane)
| Tsawg
| Tsawg heev (txhua SS OK)
|
Zone 5: Thermal Section
| MSF/MED: brine rhaub, evaporator plhaub, vapor chaw
| 60-120
| 40,000-70,000 (brine)
| < 0.1
| Tsawg (lub ntiajteb txawj nqus)
| Tsawg (kub)
| Extreme (SS ua tsis tau sai)
|
Cheeb tsam 6: Brine Discharge
| Brine outfall qhov, diffuser, mixing cheeb tsam
| 30-40
| 50,000-70,000
| Hloov pauv
| Tsawg (dilution zone)
| Nruab nrab
| Nruab nrab (dilution pab)
|
Stainless hlau qib rau Desalination daim ntaub ntawv
Rau qib stainless hlau feem ntau siv hauv cov nroj tsuag desalination, los ntawm 304L (tus nqi qis tshaj, kev ua haujlwm qis tshaj) mus rau2507 super duplex(tus nqi siab tshaj, kev ua haujlwm siab tshaj). Xaiv qhov tsis ncaj ncees lawm yuav nkim nyiaj los yog ua rau tsis ua hauj lwm ntxov.
Table 3: Stainless Hlau thiab Titanium Qib rau Desalination - Chemistry, PREN, thiab Daim Ntawv Thov Cheeb Tsam
| Qib (UNS) | Cr (%) | Tsis muaj (%) | Mo (%) | N (%) | PREN (kwv yees) | PREN Formula | Qhov siab tshaj plaws hauv dej hiav txwv (C) | Desalination Siv Zone | Tus nqi txheeb ze (vs 304L) |
304L (S30403)
| 18.0-20.0
| 8.0-12.0
| Tsis muaj
| Tsis muaj
| 18-22
| Cr nkaus xwb
| ~ 40 (limited)
| Zone 4 (cov khoom siv dej nkaus xwb)
| 1.0x (zeeg)
|
316L (S31603)
| 16.0-18.0
| 10.0-14.0
| 2.0-3.0
| Tsis muaj
| 24-30
| Cr + 3.3xMo
| ~60
| Zones 1-2 (tsawg-temp, low-Cl)
| 1.3-1.6x
|
904L (N08904)
| 19.0-23.0
| 23.0-28.0
| 4.0-5.0
| Tsis muaj
| 35-40
| Cr + 3.3xMo
| ~80
| Cheeb tsam 2-3 (Chlorinated seem)
| 2.5-3.5x
|
2205 (S32205)
| 22.0-23.0
| 4.5-6.5
| 3.0-3.5
| 0.14-0.20
| 30-35
| Cr+3.3xMo+30xN
| ~80
| Zone 3 (HP piping, SWRO)
| 2.0-3.0x
|
2507 Super Duplex (S32750)
| 24.0-26.0
| 6.0-8.0
| 3.0-5.0
| 0.20-0.30
| 40-43
| Cr+3.3xMo+30xN
| ~100
| Zone 3 (HP twj tso kua mis, TBH inlets)
| 3.5-5.0x
|
Titanium Gr.2 (R50400)
| Tsis muaj
| Tsis muaj
| Tsis muaj
| Tsis muaj
| ~0 (tsis yog Cl-pitting)
| Tsis muaj pitting hauv seawater
| Tag nrho cov temps
| Zone 5 (TBH, MSF/MED heat exchangers)
| 8-15x (tab sis lub neej ntev tshaj plaws)
|
PREN - Tus lej tseem ceeb rau kev xaiv qib Desalination
Pitting Resistance Equivalent Number (PREN) yog tus lej tseem ceeb tshaj plaws rau kev xaiv cov hlau tsis muaj chloride. Nws yog xam los ntawm cov alloy chemistry thiab kwv yees qhov kub ntawm qhov pitting yuav tshwm sim nyob rau hauv ib tug muab chloride concentration.
PREN=%Cr + 3.3 x %Mo + 16 x %N
PREN ntsuas kev tiv thaiv rau pitting pib. PREN siab dua txhais tau hais tias cov hlau tuaj yeem tiv taus ntau dua chloride concentration lossis kub ua ntej pitting pib. Hauv dej hiav txwv (~ 20,000 ppm Cl-), PREN tsawg kawg yog 30 feem ntau pom zoo rau kev ua haujlwm tas li ntawm qhov kub thiab txias.
Table 4: PREN Ranges thiab Seawater Application Limits rau Stainless Hlau Qib
| PREN Ntau | Qib(s) | Hom PREN | Seawater Application Limit | CIP qhov ntsuas kub (C) |
< 25
| 304L, 316L (tus qauv)
| 18-30
| Pits at >40C hauv dej hiav txwv
| < 25
|
25-35
| 316L (siab -C), 904L, 2205 Duplex
| 30-40
| Muaj kev nyab xeeb txog li 60-80C hauv dej hiav txwv
| 25-35
|
35-43
| 904L, 2507 Super Duplex
| 35-43
| Muaj kev nyab xeeb txog 80-100C hauv dej hiav txwv; SWRO HP ntu
| 35-45
|
43+
| 2507, Alloy 254 SMO
| 43-50
| Tshwj xeeb rau cov xwm txheej hnyav
| 45-55
|
Zero pitting kev pheej hmoo
| Titanium Qib 2
| N/A (Ti tiv thaiv rau Cl-pitting)
| Tag nrho cov dej hiav txwv kub
| Txhua qhov kub thiab txias
|
Stainless Hlau Qib Xaiv los ntawm Kev Cog Lus
Raw Seawater Intake (Zone 1)
Cov dej hiav txwv nyoos yog qhov chaw nkag rau seawater. Kub: 20-32C (nws txawv ntawm qhov chaw thiab lub caij). Chloride: 18,000-22,000 ppm. Dissolved oxygen: 4-8 ppm. Kev khiav ceev: 1-3m / s. Qhov kev pheej hmoo corrosion tseem ceeb yog microbiologically cuam tshuam corrosion (MIC) los ntawm biofilm thiab qis-ceev sediment tsub zuj zuj.
Table 5: Stainless Steel Qib Xaiv - Raw Seawater Intake (Zone 1)
| Khoom siv | Pom zoo Qib | UNS Number | Kev ncaj ncees | Alternative Qib |
Intake screens
| 316L
| S31603
| Txheem rau ambient seawater; txaus rau qis -temp kom tsawg
| 904L yog biofouling hnyav
|
Intake yeeb nkab (pob zeb-lined)
| 316L (Liab)
| S31603
| Pob zeb plhaub + SS liner; 316L txaus
| 2205 yog tias cov yeeb nkab tau faus tag nrho SS
|
Cov twj tso kua mis (casing)
| 316L los yog CD4MCu duplex
| S31603 / J93370
| 316L OK rau cov twj tso kua mis ntawm ambient temp
| CD4MCu rau siab - taub hau twj
|
Seawater cia tank (hnub tank)
| 316L
| S31603
| ambient kub; 316L txaus rau bulk cia
| 904L rau tank nrog siab Cl - koob
|
Tsawg- tso dej tso dej siab
| 316L
| S31603
| Tsis tshua muaj siab; ambient temp; 316L txaus
| 2205 rau cov nroj tsuag loj
|
Ua ntej-Txoj Kev Kho Mob (Zone 2)
Ua ntej-kev kho mob ntxiv coagulants (FeCl3, polyelectrolyte), acid (H2SO4 los yog HCl los kho pH), thiab biocides (NaOCl rau chlorination, los yog chloramines). Ntu no muaj cov chemistry nyuaj tshaj plaws hauv cov nroj tsuag. Cov tshuaj chlorine yog qhov hloov pauv tseem ceeb: 1-3 ppm txuas ntxiv chlorination ua rau muaj kev pheej hmoo loj rau 316L.
Table 6: Stainless Steel Qib Xaiv - Ua Ntej-Tshuaj Kho Mob (Zone 2)
| Khoom siv | Pom zoo Qib | UNS Number | Ntsiab Corrosion Kev txhawj xeeb | Alternative Qib |
Cartridge lim cov hlab ntsha
| 316L
| S31603
| ambient kub; 316L txaus; check Cl koob
| 904L rau siab -Cl dosing
|
Flocculation tank (yog SS -lined)
| 316L
| S31603
| FeCl3 coagulant yog me ntsis corrosive; 316l ua
| 2205 rau tank loj
|
Acid dosing kab (H2SO4)
| 316l 904 ua
| S31603 / N08904
| H2SO4 txo cov kua qaub; 316L OK ntawm qhov kub thiab txias; 904L nyiam rau cov concentrated acid
| 316L txaus rau dilute H2SO4
|
Sodium hypochlorite (NaOCl) kab
| 904l2205 ua
| N08904 / S32205
| NaOCl (1-3 ppm Cl2 sib npaug) ua rau pitting hauv 316L siab dua 30C; yam 904l
| 2205 nyiam rau 3+ ppm Cl2
|
Anti-scalant dosing kab
| 316L
| S31603
| Mob me; 316L txaus
| 904L rau scale inhibitor nrog Cl -
|
Degasifier (CO2 tshem tawm)
| 316L
| S31603
| Tsawg kub; 316l ua;. CO2 tsis yog tus tsav tsheb corrosion
| 904L rau siab -temp degasifier
|
SWRO Siab-Txoj Haujlwm Siab (Zone 3) - Thaj Chaw Tseem Ceeb
SWRO siab -siab (HP) seem yog lub plawv ntawm ib qho SWRO nroj tsuag thiab qhov siab tshaj plaws - cheeb tsam txaus ntshai rau stainless hlau corrosion. Cov dej hiav txwv nkag ntawm ~ 25C thiab tawm ntawm cov dej concentrated ntawm 40-50C thiab 55-80 bar siab. Cov tshuaj chloride concentration hauv cov concentrate (tsis kam lees) nce mus txog 25,000-35,000 ppm Cl-. Kev sib xyaw ua ke ntawm kev kub siab, kub siab, thiab siab chloride concentration yog qhov hnyav heev.
Table 7: Stainless Steel Qib Xaiv - SWRO Siab-Txoj Haujlwm Siab (Zone 3)
| Khoom siv | Pom zoo Qib | UNS Number | Critical Design Params | Alternative Qib |
HP twj tso kua mis manifold
| 2507 Super Duplex lossis 2205
| S32750 / S32205
| 55-80 bar siab; 25-40C; concentrate kwj; Qhov ceev tshaj plaws (3-5 m / s)
| 2205 siv tau rau <70 bar; 2507 xav tau rau 70-80 bar
|
Siab - cov kav dej siab (sau ntawm daim nyias nyias)
| 2205 (S32205)
| S32205
| 55-80 bar; 25-40C; dej hiav txwv + chlorination residual
| 2507 rau siab -Cl concentrate section
|
Ua kom cov kav dej (post-membrane, siab-Cl)
| 2507 Super Duplex
| S32750
| 35,000-40,000 ppm Cl-; 35-50C; siab siab (55-65 bar)
| 2205 siv tau rau <30,000 ppm Cl- thiab <35C
|
Siab hlab ntsha (membrane vaj tse)
| 316L lossis 2205 (sab hauv)
| S31603 / S32205
| Sab hauv wetted nto; cov khoom siv dej (< 500 ppm Cl-); 316L OK here
| 2205 rau siab -salinity pub
|
Cov khoom siv hluav taws xob rov qab (ERI / PTEC)
| Duplex 2205 lossis 2507
| S32205 / S32750
| Kev nrawm nrawm; abrasive hais; chlorination; 55-80 hli
| 2507 nyiam rau kev pabcuam Erosive
|
Interstage piping (booster twj tso kua mis)
| 2205 Duplex
| S32205
| Nruab nrab siab (35-55 bar); 25-35 C
| 316L OK rau qis- theem siab
|
Sampling kab
| 316L
| S31603
| Tsis tshua muaj siab; ambient temp; sampling nkaus xwb
| 904L rau cov qauv chlorinated
|
Thermal Desalination Section (Zone 5) - MSF thiab MED
Thermal seem ntawm MSF thiab MED cov nroj tsuag yog qhov xav tau tshaj plaws corrosion ib puag ncig nyob rau hauv tej desalination nroj tsuag. Brine kub ncav cuag 90{11}}120C (MSF sab saum toj brine) thiab 70-90C (MED). Chloride concentrations ncav cuag 50,000-70,000 ppm hauv cov concentrate. Ntawm cov kub thiab cov tshuaj chloride concentrations, tsis muaj austenitic stainless hlau (304L, 316L, 904L) yog txhim khu kev qha rau kev pab mus ntev. Titanium Qib 2 yog tus qauv rau kev sib pauv cua sov hauv MSF / MED cov nroj tsuag.
Table 8: Stainless Hlau / Titanium Qib Xaiv - Thermal Desalination Section (Zone 5)
| Khoom siv | Pom zoo Qib | Alternative Qib | Vim li cas Tsis Stainless Hlau |
MSF evaporator brine rhaub (plhaub)
| Cov pa roj carbon steel (epoxy-lined lossis roj hmab-lined)
| -
| Kub kub (120C) brine; CS txaus nrog hauv ob sab phlu
|
MSF tshav kub txauv tubes (thawj)
| Titanium Qib 2 (UNS R50400)
| Copper -nickel 90/10 (rau cov theem qis)
| Tsis muaj SS muaj sia nyob 90-120C dej hiav txwv mus ntev
|
MSF tshav kub txauv raj (tom qab theem)
| Titanium Qib 2 los yog CuNi 90/10
| 316L (tsuas yog rau theem qis dua 60C, kawg 2-3 theem)
| 316L tsis nyob hauv <3 xyoos siab dua 70C hauv dej hiav txwv
|
MED evaporator tubes (zoo 1-3)
| Titanium Qib 2
| -
| Cov teebmeem 1-3 khiav ntawm 70-90C; tsis muaj SS txaus
|
MED evaporator tubes (cov teebmeem 4+)
| CuNi 90/10 los yog 316L
| Titanium Qib 2 rau cov nyhuv kawg
| Tsawg kub (50-70C); 316L marginally ok
|
Vapor taub hau qhov chaw (MSF / MED)
| 316L los yog 2205 (rau tsis yog -condensable gas zones)
| Titanium Qib 2
| High temp vapor + non-condensables; 316L rau condenser plhaub
|
Brine recirculation twj tso kua mis casings
| CD4MCu (duplex cam khwb cia) los yog 316L (coated)
| Titanium Qib 2 (rau kub brine)
| Kub brine (80-120C); 316L tsis ua haujlwm; CuNi tsis txaus
|
MSF distillate tais
| 316L
| 2205 Duplex (rau siab tshaj tawm)
| 60 -}90C; 316L txaus; 2205 rau qhov siab tshaj plaws
|
Tus nqi sib piv thiab lub neej voj voog
Stainless hlau raug nqi ntau dua li cov pa roj carbon steel lossis lined carbon steel, tab sis tag nrho cov nqi ntawm lub neej (LCC) nyiam cov hlau tsis zoo hauv kev siv desalination. Tshooj lus no qhia txog kev lag luam.
Table 9: Kev sib piv tus nqi ntawm lub neej - Stainless Steels thiab lwm yam hauv Seawater Service
| Khoom siv / Qib | Qhov ceev (g / cm3) | Tus nqi txheeb ze Index (Base=CS) | Tsim Lub Neej Hauv Seawater (xyoo) | Tus nqi Index txhua xyoo | Tus nqi kho mob (ib xyoos) |
Carbon Steel (tsis muaj coated)
| 7.85
| 1.0x
| 1-3
| HIGH (hloov txhua 2 xyoos)
| Siab (corrosion tus nqi 0.3-1.0mm / xyoo)
|
Carbon Steel (rubber -liab)
| 7.85
| 1.5-2.0x
| 10-15
| Nruab nrab
| Tsawg (xyuas cov kab hauv txhua 5 xyoos)
|
316L Stainless hlau
| 7.98
| 3.5-4.5x
| 20-30
| Tsawg
| Tsawg heev
|
2205 Duplex Stainless hlau
| 7.80
| 5.0-7.0x
| 25-35
| Tsawg
| Tsawg heev
|
2507 Super Duplex Stainless Hlau
| 7.80
| 8.0-12.0x
| 30-40
| Tsawg
| Tsis tsim nyog
|
Titanium Qib 2
| 4.51
| 15.0-25.0x
| 30-50+
| Low (txawm hais tias siab upfront)
| Tsis pom zoo (zero active corrosion)
|
Lub 90/10
| 8.94
| 4.0-6.0x
| 15-25
| Nruab nrab
| Tsawg (me me biofouling)
|
Kev tsim khoom thiab cov khoom siv rau Desalination Stainless Steel
Table 11: Kev tsim khoom thiab cov khoom siv rau Desalination Stainless Steel
| Txuj | Lub Npe | Siv Rau | Cov Lus Qhia Tseem Ceeb | Thaum Yuav Tsum Tau |
ASTM A240/A240M
| Txheem Specification rau Chromium thiab Chromium-Nickel Stainless Hlau Phaj, Ntawv, thiab Sawb
| Daim ntawv thiab phaj rau cov hlab ntsha siab
| Chemistry txwv, mechanical properties, hardness, mill test report
| Yuav tsum tau rau tag nrho stainless hlau ntawv thiab phaj
|
ASTM A789 / A789M / ASTM A789 / ASTM A789 / ASTM A789 / TS
| Txheem Specification rau Seamless thiab Welded Ferritic / Austenitic Stainless Hlau Tubing
| Seamless duplex thiab super duplex tubing
| Chemistry, mechanical properties, HIC test (rau qhov chaw qaub)
| Yuav tsum tau rau tag nrho cov duplex raj
|
ASTM A790 / A790M / ASTM A790 / ASTM A790 / ASTM A790 / ASTM A790 / A790M / ASTM A790 / ASTM A790 / ASTM A790 / A790M / ASTM A790 / A790M / ASTM A790 / A790M / ASTM A790 / A790M / ASTM A790 / ASTM A790 / ASTM A790 / ASTM A790 / A790M / ASTM A790 / A790M / ASTM A790 / A790M / ASTM A790 / ASTM A790 / A790M / ASTM A790 / A790M / ASTM A790 / ASTM A790 / A790M / ASTM A790 / ASTM A790 / A790M) thiab ASTM A790 / A790M
| Standard Specification rau Seamless thiab Welded Ferritic / Austenitic Stainless hlau yeeb nkab
| Seamless duplex yeeb nkab
| Ib yam li A789; ntxiv rau qhov ntev ntev, kev sim hydrostatic
| Yuav tsum tau rau tag nrho cov yeeb nkab duplex
|
ASTM A268 / A268M ASTM
| Standard Specification rau Seamless thiab Welded Ferritic Stainless Hlau Tubing
| Ferritic SS raj (tsis siv hauv desalination)
| -
| Tsis siv tau
|
ASME BPVC Section II Part A
| ASME Boiler thiab Pressure Vessel Code, Tshooj II, Ntu A (Cov khoom siv ferrous)
| Cov khoom siv rau ASME-stamped nkoj
| Cov khoom tsim nyog, kev kho cua sov, kev sim
| Rau cov hlab ntsha siab nrog ASME stamp
|
TS EN 10028-7
| Cov khoom lag luam tiaj tus rau lub hom phiaj siab - Ntu 7: Cov Hlau Stainless
| Phaj thiab ntawv rau cov cuab yeej siv siab (EU)
| Ib yam li ASTM A240
| EU tej yaam num; EN- cov teb chaws tus qauv
|
ISO 21457 Kev Tswj Xyuas Kev Lag Luam
| Petroleum thiab Natural Gas Industries - Cov khoom siv rau Seawater Injection Systems
| Seawater Piping Systems (General)
| PREN yam tsawg kawg nkaus; Cov kev xav tau ntawm kev kuaj corrosion
| International roj & roj; desalination siv
|
DNVGL-RP-B101
| Pom zoo xyaum rau Corrosion Resistant Alloys hauv Seawater
| Seawater piping thiab heat exchangers
| PREN, Mo%, N%; kub txwv; xeem cov cai
| Nordic tej yaam num; DNV-cov nkoj cais
|
NACE MR0175 / ISO 15156
| Cov ntaub ntawv rau H2S-Containing Environments
| Sour service desalination (tsis tshua muaj)
| Cov ntaub ntawv xav tau rau H2S kev pabcuam
| Tsuas yog yog H2S tam sim no (roj-tej dej co- ntau lawm)
|
Cov lus nug nquag
Q: Dab tsi yog qib stainless hlau feem ntau siv hauv cov nroj tsuag desalination?
A: 316L stainless hlau (UNS S31603) yog qib siv dav tshaj plaws hauv cov nroj tsuag desalination, npog kwv yees li 60-70% ntawm tag nrho cov khoom siv stainless hlau (siv, ua ntej- cov tank kho, cov kav dej, thiab qis- ntu siab). Rau cov khoom siv hluav taws xob siab SWRO thiab cov ntu thermal, 2205 duplex thiab Titanium Qib 2 feem yog cov qauv.
Q: 316L stainless hlau puas tuaj yeem siv rau hauv dej hiav txwv?
A: Yog, tab sis tsuas yog nyob rau hauv tej yam kev mob: ambient kub (qis dua 30-40C), tsis tshua muaj khiav ceev (qis dua 2 m / s), tsis muaj chlorination los yog tsawg chlorination (qis dua 1 ppm), thiab tsis muaj nyob rau hauv - deposit tej yam kev mob. Hauv kev xyaum, 316L yog txaus rau cov dej hiav txwv nyoos (Zone 1) thiab cov khoom siv dej (Zone 4). Nws tsis tsim nyog rau kev kho mob ua ntej chlorinated (Zone 2), SWRO HP ntu (Zone 3), lossis ntu thermal (Zone 5).
Q: PREN yog dab tsi thiab vim li cas nws tseem ceeb rau desalination?
A: PREN (Pitting Resistance Equivalent Number)=%Cr + 3.3 x %Mo + 16 x %N. Nws kwv yees qhov chloride concentration thiab kub ntawm qhov pitting yuav pib. Hauv dej hiav txwv (~ 20,000 ppm Cl-), PREN tsawg kawg yog 30 raug pom zoo rau kev ua haujlwm tas mus li . 316L (PREN ~ 24-30) yog marginal; 2205 (PREN ~ 30-35) yog txaus; 2507 (PREN ~ 40-43) yog qhov nyiam tshaj plaws rau thaj chaw ua phem tshaj plaws.
Q: Vim li cas titanium siv hauv MSF / MED desalination nroj tsuag?
A: Titanium Qib 2 (UNS R50400) tiv thaiv pitting thiab crevice corrosion nyob rau hauv dej hiav txwv ntawm txhua qhov kub txog li 260C. Nyob rau sab saum toj brine kub ntawm MSF nroj tsuag (90-120C) thiab MED nroj tsuag (70{9}}90C), tsis muaj stainless hlau qib yuav ciaj sia mus ntev. Titanium muaj xoom active corrosion nyob rau hauv seawater: titanium oxide zaj duab xis (TiO2) yog ruaj khov thiab kho tus kheej yog tias puas. Nws tsuas yog txwv yog tus nqi (8-15x tshaj 316L) thiab rhiab heev rau crevice corrosion nyob rau hauv stagnant tej yam kev mob ntawm siab kub.
Q: Dab tsi yog qhov txawv ntawm 2205 duplex thiab 2507 super duplex stainless hlau?
A: Qhov sib txawv tseem ceeb yog: (1) 2507 muaj ntau dua chromium (24-26% vs 22-23%), siab dua molybdenum (3-5% vs 3.0-3.5%), nitrogen ntau dua (0.20-0.30% vs 0.14-0.20%); (2) 2507 muaj ntau dua PREN (40-43 vs 30-35); (3) 2507 muaj zog tensile ntau dua (800 MPa vs 620 MPa rau 2205); (4) 2507 yog siv rau cov cheeb tsam uas xav tau tshaj plaws (SWRO HP twj tso kua mis manifolds, concentrate piping ntawm 40C +); 2205 yog siv rau dav SWRO HP piping.
Q: Yuav ua li cas chlorination cuam tshuam rau stainless hlau xaiv?
A: Chlorination (NaOCl dosing) yog qhov tseem ceeb tshaj plaws kev ua haujlwm sib txawv hauv kev xaiv stainless hlau desalination. Chlorine tsa lub peev xwm oxidation ntawm cov dej hiav txwv, uas ua rau kom pitting . 316L pitting tshwm sim ntawm 1 ppm Cl2 ntawm 30C thiab ntawm 0.3 ppm Cl2 ntawm 50C. Rau cov dej tsis tu ncua chlorinated seawater (2-3 ppm), siv 904L yam tsawg kawg nkaus (PREN 35-40). Rau kev poob siab chlorination (5-10 ppm), siv 2205 duplex lossis siab dua.
Q: Dab tsi ua rau hauv qab - deposit corrosion nyob rau hauv desalination nroj tsuag thiab yuav tiv thaiv li cas?
A: Nyob rau hauv - deposit corrosion (UDC) tshwm sim thaum sediment, nplai, los yog biofilm accumulates nyob rau hauv cov yeeb nkab phab ntsa, tsim ib tug txawv aeration ntawm tes (oxygen-depleted cheeb tsam nyob rau hauv lub deposit corrodes thaum lub cheeb tsam ib puag ncig tiv thaiv). Hauv kev desalination, UDC yog thawj hom tsis ua haujlwm rau 316L hauv kev noj thiab ua ntej- ntu kho. Kev Tiv Thaiv: (1) tswj kev khiav nrawm dua 1.5 m / s kom tiv thaiv cov av av; (2) qhia meej du - bore piping (cov kav dej huv es tsis yog welded yeeb nkab nrog cov hlaws sab hauv); (3) siv 904L los yog 2205 nyob rau hauv cov cheeb tsam uas muaj kev tso nyiaj tsub zuj zuj (khoov, ceg tuag, qis- ntu nrawm).
Q: Dab tsi yog qhov tsim lub neej ntawm stainless hlau hauv daim ntawv thov desalination?
A: 316L: 20-30 xyoo hauv Zones 1-2; 2205 duplex: 25-35 xyoo nyob rau hauv Zone 3; 2507 super duplex: 30-40 xyoo hauv Zone 3; Titanium Qib 2: 30-50+ xyoo nyob rau hauv Cheeb Tsam 5. Kev pab cuam lub neej nyob ntawm: kub, chloride concentration, ntws tshaj tawm, chlorination regime, thiab fabrication zoo.
