Nyob rau hauv xyoo tas los no, kev siv lub siab - siab rov qab osmosis membrane tshuab rau ntxiv concentration thiab txo ntim ntawm industrial concentrated brine tau dhau los ua tus qauv tseem ceeb hauv xoom- tso tawm brine kho. Txawm li cas los xij, kev ntsuas qhov ntsuas tau dhau los ua ib qho ntawm cov kev txwv rau siab - concentration thiab ntim txo cov dej nkag hauv cov txheej txheem rov qab osmosis membrane. Lub ntsiab yog vim li cas rau qhov no yog tias thaum lub sij hawm siab - cov txheej txheem concentration ntawm cov dej tuaj nyob rau hauv lub rov qab osmosis membrane system, divalent cations xws li calcium, magnesium, barium, thiab strontium, nrog rau yooj yim scaling ions xws li carbonate, sulfate, phosphate, fluoride, thiab soluble silica, accumulates nyob rau hauv lub concentrate osmaturation ntawm lub xeev cov txheej txheem ntawm reacts. precipitates thiab scaling. Qhov no ua rau daim nyias nyias fouling, nce kev khiav hauj lwm siab, teeb meem nyob rau hauv restore daim nyias nyias flux, thiab nyob rau hauv mob hnyav, kev puas tsuaj rau daim nyias nyias txheej txheej, ua rau lub cev malfunction thiab ua tsis ruaj tsis khov.
Yog li ntawd, kev txhim khu kev qha thiab ua tau zoo softening thiab hardening tshem tawm txheej txheem rau concentrated brine yog ib qho tseem ceeb thiab tseem ceeb kauj ruam nyob rau hauv lub industrial concentrated brine membrane concentration thiab ntim txo cov txheej txheem.
1. Reaction Mechanism of Chemical Softening
Rau cov dej nyoos ntawm qhov sib txawv hardness, cov kev ntsuas hauv qab no feem ntau tuaj yeem ua:
(1) Rau cov dej tsis qab- tawv nqaij tawv, kho cov pH thiab qhov kub thiab txias ntawm cov neeg muaj zog lossis siv lub cev txoj hauv kev los cuam tshuam cov nplai tsim thiab txhim kho cov solubility ntawm sparingly soluble ntsev;
(2) Rau nruab nrab - cov dej tsis muaj zog tsis tshua muaj zog, cov tshuaj tiv thaiv kab mob tuaj yeem siv tau, tab sis cov no tsuas yog siv tau nyob rau hauv ib qho kev ntsuas, piv txwv li, Langerile Index (LSI) yuav tsum nyob nruab nrab ntawm 0 thiab 1.8;
(3) Rau siab -cov dej nyoos tawv, ion txauv thiab dej nag yog tsim nyog los tshem tawm cov nplais - tsim ions.
Rau cov ntim loj ntawm siab -hardness concentrated brine, siv ion pauv softening nrog cations xws li calcium thiab magnesium yuav xav tau ib tug loj npaum li cas ntawm cov regeneration agents, ua rau cov nqi khiav hauj lwm siab thiab cov pa phem thib ob. Feem ntau, cov txheej txheem kev kho kom zoo tshaj plaws suav nrog kev ntxiv cov tshuaj softening agents (sodium hydroxide, calcium hydroxide, sodium carbonate, thiab lwm yam) kom cov pH ntawm cov dej, reacting nrog calcium thiab magnesium ions nyob rau hauv cov concentrated brine los ua precipitates xws li calcium carbonate thiab magnesium hydroxide. Cov tshuaj tiv thaiv mechanism ntawm tshuaj softening yog raws li nram no:
Ca2+ + CO32- → CaCO3 ↓
Ca2+ + OH- + HCO3- → CaCO3 ↓ + H2O
Mg2+ + 2OH- → Mg(OH)2 ↓
Nyob rau hauv cov qauv, "↓" qhia tau hais tias ib tug precipitate tau tsim, piv txwv li, ib tug suspended khoom. Txiv qaub thiab kua alkali tuaj yeem muab cov hydroxide ions xav tau rau cov tshuaj tiv thaiv; Yog hais tias cov carbonate ions nyob rau hauv dej tsis txaus, soda tshauv tuaj yeem ntxiv los ntxiv cov carbonate ions.
SiO2 + 2Mg(OH)2↓ → Mg2SiO4↓ + 2H2O
Cov tshuaj tiv thaiv kev tshem tawm silica yog qhov nyuaj dua, tab sis nws tuaj yeem nkag siab yooj yim raws li kev sib koom ua ke- nag lossis daus cov tshuaj tiv thaiv ntawm silica hauv dej thiab magnesium hydroxide generated hauv cov tshuaj tiv thaiv softening. Tom qab ntawd, cov khoom sib cais - kua sib cais yog ua tiav los ntawm txoj kev xws li kev pom thiab kev qhia meej kom tshem tawm cov silica.
Fluoride, barium, thiab strontium ions nyob rau hauv concentrated brine kuj ua rau muaj kev pheej hmoo ntawm scaling ntawm rov qab osmosis membrane. Nyob rau hauv lub pH tej yam kev mob ntawm cov tshuaj softening cov tshuaj tiv thaiv, cov hnyav hlau ions yuav ib txhij tsim insoluble precipitates (calcium fluoride, barium sulfate, strontium sulfate, thiab lwm yam), uas yog tom qab tshem tawm los ntawm pom.
2. Xaiv cov tshuaj ntxiv
Txiv qaub (nrog dej qab zib tshauv) los yog kua alkali nrog dej qab zib tshauv tuaj yeem siv tau los ua cov tshuaj softening rau concentrated brine hardening. Lub hom phiaj ntawm cov tshuaj tiv thaiv yog los hloov cov calcium thiab magnesium ions hauv dej rau hauv lawv cov khoom insoluble, uas tom qab ntawd tshem tawm los ntawm kev pom, thaum tib lub sijhawm tshem tawm barium, strontium, silica, thiab lwm yam. Cov txiv qaub yog pheej yig dua thiab yooj yim dua li cov kua alkali, tab sis nws nce cov sludge thiab nthuav qhia ntau cov calcium ions ntawm requi carbonate. nag xob nag cua.
Yog hais tias cov concentration ntawm bicarbonate + carbonate nyob rau hauv cov dej tsis txaus rau precipitate cov calcium ions qhia los ntawm cov txiv qaub, soda tshauv yuav tsum tau ntxiv nyias, tab sis soda tshauv yog kim heev. Ntxiv kua alkali yuav tsis qhia calcium ions. Txawm li cas los xij, nws yuav tsum tau txiav txim siab tias yog tias qhov concentration ntawm bicarbonate + carbonate ions hauv dej yog siab dua li calcium ion concentration, yuav muaj ntau tshaj alkalinity. Qhov no yuav ua rau cov kua qaub ntau dhau thaum pH ntawm softened permeate yuav tsum tau kho rov qab mus rau nruab nrab, thiab muaj kev pheej hmoo tias cov conductivity ntawm permeate tom qab rov qab osmosis membrane kev kho mob yuav tsis ua raws li cov qauv.
Hauv cov ntsiab lus, nyob rau hauv feem ntau cov dej tsis zoo (qhov twg cov concentration ntawm bicarbonate + carbonate ions ntau dua li cov calcium ion concentration), siv cov txiv qaub + kua alkali ua ib tug softening neeg sawv cev yog ntau yig thiab tsim nyog. Thaum cov dej nyoos muaj siab hardness tab sis tsis tshua muaj alkalinity, ntxiv cov kua alkali tsuas yog qhov zoo. Thaum cov dej nyoos muaj alkalinity siab heev, ntxiv cov txiv qaub tsuas yog siv nyiaj ntau dua thiab tsim nyog.
Ntxiv magnesium ntsev aims kom tshem tawm silicon. Cov tshuaj tiv thaiv softening tsim magnesium hydroxide, uas ib txhij ua insoluble co-precipitates nrog silica hauv dej los ntawm adsorption thiab tshuaj lom neeg cov tshuaj tiv thaiv. Magnesium ntsev muaj xws li magnesium oxide thiab magnesium chloride. Magnesium oxide feem ntau pheej yig thiab yooj yim muaj, tab sis nws yog ib qho nyuaj rau lis, reacts maj mam, thiab yuav tsum tau ib tug tej yam kub thiab txias. Magnesium chloride kuj tseem kim dua, tab sis nws yooj yim soluble thiab tuaj yeem ua rau hauv cov kua dej, ua rau nws yooj yim los tuav thiab ua haujlwm sai. Feem ntau, magnesium ions nyob rau hauv concentrated brine yog txaus rau precipitate silica, tab sis nyob rau hauv tshwj xeeb dej qhov chaw, txaus magnesium ntsev thiab kua alkali yuav tsum tau ntxiv ntxiv kom tshem tawm silica.
3. Tshuaj Softening nyhuv
Ua ib qho piv txwv ntawm softening ntawm cov tshuaj khib nyiab, cov dej nyoos yog cov dej khib nyiab tom qab kev kho mob anaerobic thiab yuav tsum tau siv cov txheej txheem disc raj rov qab osmosis (DTRO). Cov dej muaj tag nrho hardness thiab tag nrho alkalinity, thiab cov ntsiab lus silica tsawg. Txhawm rau zam kom tsis txhob muaj calcium thiab magnesium ion scaling rau ntawm cov dej concentrated thaum lub sij hawm siab - concentration thiab ntim txo kev kho ntawm DTRO, tshuaj softening yuav tsum tau tshem tawm hardness.
Raws li cov yam ntxwv ntawm cov dej khib nyiab, kua alkali (30% sodium hydroxide tov) raug xaiv los ua cov tshuaj softening. Cov laj thawj yog raws li nram no: Tag nrho cov hardness ntawm cov dej nyoos yog 1100-1500 mg / L, nrog calcium hardness tshaj magnesium hardness, thaum tag nrho alkalinity yog 2300-2500 mg / L. Nyob rau hauv alkaline tej yam kev mob, cov bicarbonate thiab carbonate ions nyob rau hauv cov dej nyoos yog txaus los teb rau tag nrho cov calcium ions nyob rau hauv dej los tsim calcium carbonate precipitate, yog li tag nrho tshem tawm calcium hardness. Nyob rau tib lub sijhawm, tag nrho cov magnesium ions hnov mob nrog ntau tshaj hydroxide ions hauv cov tshuaj alkali los tsim magnesium hydroxide precipitate, thiab nqa qee cov silica los ntawm cov dej hauv cov tshuaj tiv thaiv nag lossis daus, yog li tshem tawm magnesium hardness thiab qee cov silica.
Raws li cov ntaub ntawv ua ntej thiab tom qab muag muag, nws tuaj yeem pom tias cov tshuaj softening ua tiav 97% tshem tawm tus nqi ntawm tag nrho cov tawv nqaij los ntawm cov dej nyoos, thiab qhov tawv ntawm cov khoom muag muag dej yog tsawg dua 100 mg / L, ua tau raws li cov kev cai rau cov dej hardness hauv DTRO membrane cov khoom siv concentration thiab ntim txo cov txheej txheem kho.
Nyob rau hauv kev lag luam concentrated brine membrane concentration thiab ntim txo kev kho mob, tshuaj softening yog ib tug heev npaum, yig, thiab tswv yim kho technology rau hardness tshem tawm.
