Tshuaj softening yog txheej txheem uas yuav ntxiv cov tshuaj tshwj xeeb rau dej los hloov cov calcium thiab magnesium ions hardening rau hauv cov tebchaw insoluble, uas tom qab ntawd tshem tawm los ntawm nag lossis daus thiab pom. Qhov no yog ib tug classic thiab zoo hardening tshem tawm technology.
I. Hloov ntawm nag lossis daus-Kev sib cais sib npaug
Lub hauv paus theoretical ntawm txoj kev no yog lub hauv paus ntsiab lus ntawm cov khoom solubility. Ntawd yog, los ntawm kev ntxiv cov tshuaj rau hauv dej, qhov concentration ntawm anions uas tuaj yeem tsim cov dej tsis sib haum nrog calcium thiab magnesium ions (xws li CO3^2-, OH-, PO4^3-, thiab lwm yam) yog nce, ua rau cov khoom ion tshaj nws cov khoom solubility tas li, yog li tsim los nag.
Cov tshuaj tiv thaiv nag lossis daus tseem ceeb suav nrog:
1. Tshem tawm cov carbonate hardness:
Ca(HCO3)2 + Ca(OH)2 ->2CaCO3↓ + 2H2O
Mg(HCO3)2 + 2Ca(OH)2 ->2CaCO3↓ + Mg(OH)2↓ + 2H2O
Txiv qaub muab OH- ions los hloov bicarbonate ions rau carbonate ions thiab nce pH los ua magnesium hydroxide precipitate.
2. Kev tshem tawm tsis yog -carbonate hardness (calcium):
CaSO4 + Na2CO3 ->CaCO3↓ + Na2SO4
CaCl2 + Na2CO3 ->CaCO3↓ + 2NaCl
Soda tshauv muab CO3^2- ions, uas ua ke nrog calcium ions los ua calcium carbonate precipitate.
3. Kev tshem tawm tsis yog -carbonate hardness (magnesium):
MgSO4 + Ca(OH)2 ->Mg(OH)2↓ + CaSO4
Lub generated CaSO4 tseem yuav tsum tau muab tshem tawm ntxiv los ntawm soda tshauv. Txiv qaub yog siv los muab OH- ions los tsim magnesium hydroxide precipitate nrog cov khoom me me solubility.
II. Feem ntau siv tshuaj Reagents thiab lawv cov haujlwm
1. Txiv qaub: Nws cov khoom tseem ceeb yog Ca(OH)2.
Tshem tawm carbonate hardness (xws li calcium thiab magnesium carbonate hardness) thiab muab pH ib puag ncig siab. Qhov ntau npaum li cas yuav tsum raug xam kom raug; Kev sib ntxiv ntau dhau tsis yog tsuas yog khib nyiab xwb tab sis kuj tuaj yeem ua rau magnesium ion redissolution lossis qhia cov hardness tshiab.
2. Soda Ash: Nws cov khoom tseem ceeb yog Na2CO3.
Tshem tawm tsis yog -carbonate hardness (calcium hardness) los ntawm dej. Nws dissolves nyob rau hauv dej nws tus kheej yam tsis tau qhia tshiab hardness ions, tab sis theej qhia Na +, muaj ib tug me me cuam tshuam rau cov dej zoo.
3. Sodium Hydroxide: NaOH.
Qee zaum siv los ua ib feem ntawm cov txiv qaub, muab OH- ions, ua haujlwm yooj yim dua, tab sis kim dua. Cov tshuaj tiv thaiv zoo ib yam li txiv qaub.
4. Phosphates: xws li sodium tripolyphosphate, sodium hexametaphosphate, thiab lwm yam.
Txoj kev no tsis yog ib txoj hauv kev los nag lossis daus, tab sis tiv thaiv kev tsim cov nplai los ntawm kev tsim cov colloids dispersed los yog complexing calcium thiab magnesium ions. Nws yog "txoj kev zais" lossis "qhov pib ua haujlwm," feem ntau siv rau kev kho mob lossis hauv cov xwm txheej uas tsis tshua muaj.
III. Classic txheej txheem ntws: txiv qaub-Soda Ash Method
Qhov no yog cov txheej txheem tshuaj softening tshaj plaws, thiab nws cov dej ntws yog raws li hauv qab no:
1. Reaction Tank/Softening Tank:
Cov dej nyoos ua ntej nkag mus rau hauv cov tshuaj tiv thaiv tank, qhov twg cov kua qaub slurry thiab dej qab zib tshauv yog ntxiv raws li kev suav ntau npaum li cas. Lub tank yog nruab nrog ib tug neeg kho tshuab stirring ntaus ntawv los xyuas kom meej sib tov thiab cov tshuaj tiv thaiv ntawm reagents thiab muab sij hawm txaus thiab tej yam kev mob rau precipitate tsim.
Tag nrho cov tshuaj lom neeg tseem ceeb tau hais los saum toj no tau ua tiav ntawm no, tsim kom muaj ntau ntawm CaCO3 thiab Mg (OH) 2 flocculent precipitates.
2. Sedimentation Tank/Clarification Tank:
Cov dej reacted ntws mus rau hauv lub tank sedimentation, qhov twg tus nqi ntws qeeb. Txij li thaum CaCO3 yog ib qho hnyav hnyav, nws nyob sai sai; thaum Mg (OH) 2 yog lub teeb flocculent precipitate, nws nyob qeeb dua. Flocculants (xws li PAM) feem ntau yog ntxiv los txhawb kev loj hlob ntawm floc thiab ua kom cov sedimentation. Cov lus qhia saum toj kawg nkaus mus rau cov kauj ruam tom ntej, thaum lub hauv qab sludge raug tshem tawm ib ntus.
3. Lim Tank:
Cov dej tom qab sedimentation tseem tuaj yeem muaj cov khoom me me uas raug tshem tawm, yuav tsum tau ua kom pom tseeb los ntawm ntau- lim xov xwm (xws li anthracite lossis silica xuab zeb) kom tshem tawm cov seem seem thiab ua kom cov dej ntws tawm raws li cov qauv.
4. pH Kho Tank:
Cov dej kho nrog txiv qaub muaj pH siab heev (feem ntau yog siab dua 10), ua rau nws corrosive thiab tsis tsim nyog rau kev siv tom ntej los yog tso tawm.
Yog li ntawd, cov kua qaub (xws li sulfuric acid los yog hydrochloric acid) los yog CO2 yuav tsum tau ntxiv tom qab pom kom tsis txhob muaj pH thiab coj rov qab mus rau qhov nruab nrab (piv txwv li, 6.5-8.5). Txoj kev qhia CO2, tseem hu ua "recarbonation," kuj tseem tuaj yeem hloov me me ntawm calcium ions yaj rau hauv calcium carbonate kom tshem tawm ntxiv.
IV. Cov yam ntxwv
Qhov zoo:
1. Cov txiaj ntsig tseem ceeb thiab ntseeg tau: Cov cuab yeej siv tau zoo thiab tuaj yeem txo cov tawv tawv mus rau theem qis (qhov seem hardness tuaj yeem ncav cuag 0.5-1.0 mmol / L).
2. Kev tshem tawm ib txhij ntawm lwm yam impurities: Hauv cov txheej txheem ntawm kev tshem tawm cov tawv tawv, nws tuaj yeem txo cov alkalinity, silicon cov ntsiab lus, qee cov hlau hnyav, thiab cov khoom raug tshem tawm hauv dej.
3. Tus nqi kho mob qis: Cov tshuaj reagents siv (txiv qaub, dej qab zib tshauv) muaj dav thiab pheej yig.
Disadvantages thiab Limitations:
1. Loj Sludge Production: Nws tsim ntau cov tshuaj sludge (tsuas yog muaj cov calcium carbonate thiab magnesium hydroxide), thiab kev kho thiab pov tseg ntawm cov sludge no yuav ua rau cov nqi ntxiv thiab ib puag ncig siab.
2. Kev ua haujlwm nyuaj thiab kev tswj xyuas: Kev siv cov tshuaj reagents yuav tsum tau muab xam thiab hloov kho raws li cov kev hloov pauv hauv cov dej tsis zoo, xav tau cov neeg ua haujlwm siab heev.
3. Txwv Tsis Pub Muaj Kev Zoo: Nws yog qhov nyuaj rau kev ua tiav qhov tsis tshua muaj siab hardness ntawm kev sib sib zog nqus softening (xws li,<0.03 mmol/L), and the residual hardness is still higher than that of advanced treatment processes such as ion exchange.
4. Cov hneev taw loj: Cov khoom siv yuav tsum muaj ntau cov qauv xws li cov tshuaj tiv thaiv, sedimentation, thiab filtration chaw, uas ua rau muaj kev nqis peev loj.
