電(dian)鍍廢(fei)水零排放工藝概述(shu)
電鍍(du)廢(fei)(fei)(fei)水(shui)(shui)(shui)零排(pai)(pai)放系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)一(yi)(yi)(yi)般包括(kuo)預(yu)(yu)處(chu)(chu)(chu)理(li)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、綜合(he)處(chu)(chu)(chu)理(li)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)、膜系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)和蒸發(fa)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)四大部分(fen)(fen)(fen)。預(yu)(yu)處(chu)(chu)(chu)理(li)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)應(ying)遵循(xun)分(fen)(fen)(fen)類收集、分(fen)(fen)(fen)質處(chu)(chu)(chu)理(li)的(de)(de)原(yuan)則(ze)(ze)，如(ru)酸堿廢(fei)(fei)(fei)水(shui)(shui)(shui)一(yi)(yi)(yi)般采(cai)用(yong)(yong)(yong)(yong)中和法(fa)(fa)，含(han)氰廢(fei)(fei)(fei)水(shui)(shui)(shui)采(cai)用(yong)(yong)(yong)(yong)堿性氯(lv)化(hua)法(fa)(fa)，含(han)鉻廢(fei)(fei)(fei)水(shui)(shui)(shui)采(cai)用(yong)(yong)(yong)(yong)亞硫酸鹽(yan)還原(yuan)法(fa)(fa)，含(han)鎳(nie)廢(fei)(fei)(fei)水(shui)(shui)(shui)、含(han)鎘廢(fei)(fei)(fei)水(shui)(shui)(shui)、含(han)銅廢(fei)(fei)(fei)水(shui)(shui)(shui)、含(han)鋅廢(fei)(fei)(fei)水(shui)(shui)(shui)、混合(he)廢(fei)(fei)(fei)水(shui)(shui)(shui)等(deng)則(ze)(ze)采(cai)用(yong)(yong)(yong)(yong)化(hua)學沉淀法(fa)(fa)或者離(li)子交換法(fa)(fa)進(jin)行(xing)預(yu)(yu)處(chu)(chu)(chu)理(li)[6]。經分(fen)(fen)(fen)類預(yu)(yu)處(chu)(chu)(chu)理(li)后，使(shi)各類廢(fei)(fei)(fei)水(shui)(shui)(shui)中的(de)(de)一(yi)(yi)(yi)類污(wu)染(ran)物(wu)達(da)到(dao)GB21900–2008《電鍍(du)污(wu)染(ran)物(wu)排(pai)(pai)放標準》中“表3”的(de)(de)限值要(yao)求(qiu)，一(yi)(yi)(yi)并進(jin)入(ru)綜合(he)處(chu)(chu)(chu)理(li)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)，采(cai)用(yong)(yong)(yong)(yong)深度(du)(du)物(wu)化(hua)處(chu)(chu)(chu)理(li)、生化(hua)處(chu)(chu)(chu)理(li)等(deng)技術進(jin)一(yi)(yi)(yi)步(bu)去除有機(ji)物(wu)、氨(an)氮、總氮等(deng)污(wu)染(ran)物(wu)，使(shi)出(chu)水(shui)(shui)(shui)達(da)到(dao)膜系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)的(de)(de)進(jin)水(shui)(shui)(shui)要(yao)求(qiu)，再(zai)采(cai)用(yong)(yong)(yong)(yong)多級(ji)、多段組合(he)膜工藝對(dui)廢(fei)(fei)(fei)水(shui)(shui)(shui)進(jin)行(xing)濃(nong)縮減(jian)量處(chu)(chu)(chu)理(li)。高(gao)鹽(yan)度(du)(du)的(de)(de)膜系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)濃(nong)水(shui)(shui)(shui)送至(zhi)蒸發(fa)系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)進(jin)行(xing)蒸發(fa)結晶(jing)處(chu)(chu)(chu)理(li)，一(yi)(yi)(yi)方面(mian)(mian)產出(chu)結晶(jing)鹽(yan)，另一(yi)(yi)(yi)方面(mian)(mian)得(de)到(dao)達(da)到(dao)回用(yong)(yong)(yong)(yong)水(shui)(shui)(shui)質要(yao)求(qiu)的(de)(de)膜系(xi)(xi)(xi)統(tong)(tong)(tong)(tong)產水(shui)(shui)(shui)和蒸發(fa)冷凝水(shui)(shui)(shui)，全部循(xun)環回用(yong)(yong)(yong)(yong)于生產，從而終實(shi)現(xian)電鍍(du)廢(fei)(fei)(fei)水(shui)(shui)(shui)零排(pai)(pai)放。
2.蒸發器的組成及設計要點
2.1蒸發系統的組成
目前(qian)電鍍廢(fei)(fei)水(shui)零排(pai)放(fang)工藝(yi)的蒸(zheng)發器(qi)(qi)一般采用多效蒸(zheng)發或者機械蒸(zheng)汽再壓縮(MVR)蒸(zheng)發器(qi)(qi)，其中MVR蒸(zheng)發器(qi)(qi)因為相對節能、運行(xing)費(fei)用低(di)、自動化程度(du)高(gao)等優點(dian)而在(zai)廢(fei)(fei)水(shui)零排(pai)放(fang)中得到更(geng)為廣泛的應用。
MVR蒸(zheng)(zheng)發(fa)系統一般由預(yu)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)、強(qiang)(qiang)(qiang)制(zhi)循(xun)(xun)環(huan)(huan)加(jia)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)、結(jie)(jie)(jie)晶(jing)分(fen)(fen)離(li)(li)(li)器(qi)(qi)、蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)壓縮機、離(li)(li)(li)心(xin)機、泵組、儲罐、自動(dong)控制(zhi)系統等組成(cheng)，其應用在(zai)電鍍廢水(shui)(shui)(shui)零排放工程中(zhong)(zhong)的(de)(de)(de)典型工藝流程如(ru)圖1所示。濃(nong)(nong)水(shui)(shui)(shui)經(jing)進(jin)(jin)料泵提升(sheng)、預(yu)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)預(yu)熱(re)(re)(re)(re)(re)(re)(re)后(hou)進(jin)(jin)入強(qiang)(qiang)(qiang)制(zhi)循(xun)(xun)環(huan)(huan)加(jia)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)，在(zai)其中(zhong)(zhong)被蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)加(jia)熱(re)(re)(re)(re)(re)(re)(re)后(hou)進(jin)(jin)入結(jie)(jie)(jie)晶(jing)分(fen)(fen)離(li)(li)(li)器(qi)(qi)沸騰(teng)汽(qi)(qi)(qi)(qi)化(hua)，并氣液(ye)(ye)分(fen)(fen)離(li)(li)(li)。分(fen)(fen)離(li)(li)(li)后(hou)的(de)(de)(de)濃(nong)(nong)水(shui)(shui)(shui)在(zai)強(qiang)(qiang)(qiang)制(zhi)循(xun)(xun)環(huan)(huan)泵的(de)(de)(de)作(zuo)用下再(zai)次進(jin)(jin)入強(qiang)(qiang)(qiang)制(zhi)循(xun)(xun)環(huan)(huan)加(jia)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)中(zhong)(zhong)循(xun)(xun)環(huan)(huan)濃(nong)(nong)縮，直至達到(dao)(dao)過飽和(he)(he)狀態而析(xi)出(chu)結(jie)(jie)(jie)晶(jing)鹽。含有結(jie)(jie)(jie)晶(jing)鹽的(de)(de)(de)濃(nong)(nong)水(shui)(shui)(shui)經(jing)出(chu)料泵出(chu)料，送至稠厚器(qi)(qi)進(jin)(jin)一步增濃(nong)(nong)。然(ran)后(hou)進(jin)(jin)入離(li)(li)(li)心(xin)機離(li)(li)(li)心(xin)分(fen)(fen)離(li)(li)(li)得到(dao)(dao)結(jie)(jie)(jie)晶(jing)鹽，離(li)(li)(li)心(xin)母(mu)液(ye)(ye)則經(jing)母(mu)液(ye)(ye)罐、母(mu)液(ye)(ye)泵重(zhong)(zhong)新回(hui)(hui)(hui)(hui)到(dao)(dao)結(jie)(jie)(jie)晶(jing)分(fen)(fen)離(li)(li)(li)器(qi)(qi)繼續濃(nong)(nong)縮結(jie)(jie)(jie)晶(jing)。結(jie)(jie)(jie)晶(jing)分(fen)(fen)離(li)(li)(li)器(qi)(qi)產生的(de)(de)(de)二次蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)進(jin)(jin)入蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)壓縮機，經(jing)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)壓縮機壓縮后(hou)其溫度和(he)(he)焓值(zhi)提高，然(ran)后(hou)重(zhong)(zhong)新回(hui)(hui)(hui)(hui)到(dao)(dao)強(qiang)(qiang)(qiang)制(zhi)循(xun)(xun)環(huan)(huan)加(jia)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)用作(zuo)加(jia)熱(re)(re)(re)(re)(re)(re)(re)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)，以達到(dao)(dao)重(zhong)(zhong)復利(li)用和(he)(he)節能的(de)(de)(de)目的(de)(de)(de)。加(jia)熱(re)(re)(re)(re)(re)(re)(re)蒸(zheng)(zheng)汽(qi)(qi)(qi)(qi)在(zai)強(qiang)(qiang)(qiang)制(zhi)循(xun)(xun)環(huan)(huan)加(jia)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)中(zhong)(zhong)釋放潛熱(re)(re)(re)(re)(re)(re)(re)加(jia)熱(re)(re)(re)(re)(re)(re)(re)濃(nong)(nong)水(shui)(shui)(shui)的(de)(de)(de)同時，本身被冷凝，并自流進(jin)(jin)入冷凝水(shui)(shui)(shui)罐。蒸(zheng)(zheng)發(fa)冷凝水(shui)(shui)(shui)經(jing)冷凝水(shui)(shui)(shui)泵提升(sheng)，送至預(yu)熱(re)(re)(re)(re)(re)(re)(re)器(qi)(qi)回(hui)(hui)(hui)(hui)收熱(re)(re)(re)(re)(re)(re)(re)量后(hou)作(zuo)為回(hui)(hui)(hui)(hui)用水(shui)(shui)(shui)回(hui)(hui)(hui)(hui)用到(dao)(dao)生產中(zhong)(zhong)。
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