在(zai)污(wu)水(shui)(shui)處理過程中(zhong)，利用污(wu)水(shui)(shui)蒸(zheng)發器(qi)可(ke)以(yi)將污(wu)水(shui)(shui)中(zhong)的(de)(de)(de)部(bu)分(fen)溶(rong)(rong)(rong)劑轉變為蒸(zheng)氣狀態，以(yi)提(ti)高(gao)溶(rong)(rong)(rong)液中(zhong)溶(rong)(rong)(rong)質(zhi)的(de)(de)(de)濃(nong)度或使溶(rong)(rong)(rong)質(zhi)成固體(ti)析出，這樣就可(ke)以(yi)將污(wu)水(shui)(shui)中(zhong)的(de)(de)(de)一些(xie)有(you)害(hai)成分(fen)予以(yi)排(pai)除。在(zai)多數情況下(xia)，污(wu)水(shui)(shui)蒸(zheng)發器(qi)在(zai)進(jin)行(xing)蒸(zheng)發的(de)(de)(de)同時是為了提(ti)高(gao)溶(rong)(rong)(rong)液的(de)(de)(de)濃(nong)度和(he)析出溶(rong)(rong)(rong)質(zhi)，此外，也用以(yi)分(fen)出純凈(jing)的(de)(de)(de)溶(rong)(rong)(rong)劑，達(da)到凈(jing)化(hua)水(shui)(shui)質(zhi)的(de)(de)(de)目的(de)(de)(de)。

在污水蒸(zheng)發(fa)器(qi)中(zhong)，如果污水的(de)溫度低于其本身的(de)沸(fei)點的(de)話，并且直接位于溶(rong)(rong)液(ye)表(biao)面(mian)上(shang)方(fang)溶(rong)(rong)劑(ji)蒸(zheng)汽壓大于溶(rong)(rong)液(ye)上(shang)方(fang)空間中(zhong)同(tong)一蒸(zheng)汽的(de)分壓，但小于總壓時，污水蒸(zheng)發(fa)器(qi)中(zhong)就會發(fa)生氣化(hua)反應(ying)，由(you)污水的(de)表(biao)面(mian)、在不同(tong)的(de)溫度下(xia)進行。但由(you)于氣化(hua)過程不能保證由(you)溶(rong)(rong)液(ye)中(zhong)強烈地(di)排除(chu)溶(rong)(rong)劑(ji)，使得溶(rong)(rong)液(ye)的(de)濃縮(suo)緩慢，所以很少(shao)應(ying)用。

而當(dang)污(wu)(wu)水(shui)的蒸汽壓(ya)等于溶(rong)液上方空間中(zhong)(zhong)的總壓(ya)時，污(wu)(wu)水(shui)蒸發(fa)器中(zhong)(zhong)就(jiu)會呈(cheng)現出(chu)沸騰過(guo)(guo)程(cheng)，在(zai)一定壓(ya)強與濃(nong)度的作用下，污(wu)(wu)水(shui)仍然能夠保持著一定的溫(wen)度。經(jing)過(guo)(guo)污(wu)(wu)水(shui)蒸發(fa)器的進一步作用之后就(jiu)會形成(cheng)蒸汽。所以說，在(zai)污(wu)(wu)水(shui)處理過(guo)(guo)程(cheng)中(zhong)(zhong)，污(wu)(wu)水(shui)的凈化多半(ban)是在(zai)沸騰情(qing)況下進行的。