含(han)油污水處理蒸(zheng)發器當(dang)溶(rong)(rong)(rong)(rong)液的溫度(du)低于其(qi)本身的沸(fei)點(dian)，而(er)直接位于溶(rong)(rong)(rong)(rong)液表面上方(fang)溶(rong)(rong)(rong)(rong)劑(ji)(ji)蒸(zheng)汽壓(ya)大(da)于溶(rong)(rong)(rong)(rong)液上方(fang)空(kong)間中(zhong)同(tong)一蒸(zheng)汽的分壓(ya)，但(dan)小(xiao)于總壓(ya)時(shi)，則(ze)出現(xian)氣(qi)化(hua)(hua)現(xian)象。氣(qi)化(hua)(hua)系由溶(rong)(rong)(rong)(rong)液的表而(er)、在(zai)不(bu)同(tong)的溫度(du)下進行(xing)。由于氣(qi)化(hua)(hua)過程不(bu)能保(bao)證(zheng)由溶(rong)(rong)(rong)(rong)液中(zhong)強烈地(di)排(pai)除(chu)溶(rong)(rong)(rong)(rong)劑(ji)(ji)，因之溶(rong)(rong)(rong)(rong)液的濃(nong)縮緩慢，故(gu)在(zai)工業上較少(shao)應用。當(dang)溶(rong)(rong)(rong)(rong)劑(ji)(ji)的蒸(zheng)汽壓(ya)等于溶(rong)(rong)(rong)(rong)液上方(fang)空(kong)間中(zhong)的總壓(ya)時(shi)，則(ze)進行(xing)沸(fei)騰過程。沸(fei)騰過程的特(te)點(dian)是溶(rong)(rong)(rong)(rong)液在(zai)一定(ding)的壓(ya)強與濃(nong)度(du)(或溶(rong)(rong)(rong)(rong)液的組成(cheng))下，嚴格地(di)保(bao)持著(zhu)一定(ding)的溫度(du)。