在用多(duo)(duo)孔(kong)性固體(ti)物(wu)質處(chu)(chu)理流體(ti)混(hun)合物(wu)時,流體(ti)中的某(mou)一(yi)組分(fen)或(huo)某(mou)些組分(fen)可(ke)被吸(xi)(xi)表面(mian)并濃(nong)集其(qi)上,此現象稱為吸(xi)(xi)附(fu)。吸(xi)(xi)附(fu)處(chu)(chu)理廢氣(qi)時,吸(xi)(xi)附(fu)的對(dui)象是(shi)氣(qi)態污染物(wu),氣(qi)固吸(xi)(xi)附(fu)。被吸(xi)(xi)附(fu)的氣(qi)體(ti)組分(fen)稱為吸(xi)(xi)附(fu)質,多(duo)(duo)孔(kong)固體(ti)物(wu)質稱為吸(xi)(xi)附(fu)劑。
吸收法采(cai)用低揮(hui)發或不(bu)揮(hui)發性溶劑對VOCs進行(xing)(xing)吸收,再(zai)利用VOCs和吸收劑物理性質的(de)差異進行(xing)(xing)分離(li)。
含VOCs的氣(qi)體自吸收(shou)(shou)(shou)塔(ta)底部進(jin)入(ru)塔(ta)內,在上升(sheng)過程中與來自塔(ta)頂的吸收(shou)(shou)(shou)劑逆流接觸(chu),凈(jing)化后(hou)(hou)的氣(qi)體由塔(ta)頂排出。吸收(shou)(shou)(shou)了VOCs的吸收(shou)(shou)(shou)劑通過熱交換器后(hou)(hou),廢氣(qi)處理(li)設(she)備進(jin)入(ru)汽(qi)提(ti)塔(ta)頂部,在溫度高于吸收(shou)(shou)(shou)溫度或壓力低于吸收(shou)(shou)(shou)壓力的條件下(xia)解吸。解吸后(hou)(hou)的吸收(shou)(shou)(shou)劑經過溶劑冷凝(ning)器冷凝(ning)后(hou)(hou)回到吸收(shou)(shou)(shou)塔(ta)。解吸出的VOCs氣(qi)體經過冷凝(ning)器、氣(qi)液分離(li)(li)器后(hou)(hou)以(yi)較純(chun)的VOCs氣(qi)體離(li)(li)開汽(qi)提(ti)塔(ta),被回收(shou)(shou)(shou)利用。該工藝適合(he)于VOCs濃度較高、溫度較低的氣(qi)體凈(jing)化,其他情況下(xia)需要作相(xiang)應的工藝調整。
固體表面(mian)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)了(le)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)(zhi)后,一(yi)部被(bei)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)的吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)(zhi)可從吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)劑表面(mian)脫(tuo)離,此(ci)現附(fu)(fu)(fu)(fu)(fu)。而(er)當吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)進行一(yi)段時(shi)間后,由(you)于表面(mian)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)(zhi)的濃集,使(shi)其吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)能(neng)力(li)明顯(xian)下降而(er)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)凈(jing)化的要(yao)求,此(ci)時(shi)需(xu)要(yao)采用(yong)一(yi)定的措施(shi)使(shi)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)劑上已(yi)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)的吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)(zhi)脫(tuo)附(fu)(fu)(fu)(fu)(fu),以(yi)協(xie)的吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)能(neng)力(li),這(zhe)個過(guo)程稱(cheng)為(wei)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)劑的再生。因此(ci)在實際吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)工(gong)程中,正是利用(yong)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)一(yi)再生一(yi)再吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)的循環過(guo)程,達到除去廢氣(qi)中污染物質(zhi)(zhi)(zhi)并回收廢氣(qi)中有用(yong)組分(fen)。