在用(yong)多孔(kong)性固體物(wu)質處理流體混合(he)物(wu)時(shi),流體中的某一組分(fen)或某些組分(fen)可被吸(xi)(xi)表面并濃集其上(shang),此現象(xiang)稱為吸(xi)(xi)附。吸(xi)(xi)附處理廢氣時(shi),吸(xi)(xi)附的對象(xiang)是氣態污染物(wu),氣固吸(xi)(xi)附。被吸(xi)(xi)附的氣體組分(fen)稱為吸(xi)(xi)附質,多孔(kong)固體物(wu)質稱為吸(xi)(xi)附劑。
吸(xi)收法采(cai)用(yong)低(di)揮(hui)發(fa)或(huo)不(bu)揮(hui)發(fa)性溶(rong)劑對VOCs進行吸(xi)收,再利(li)用(yong)VOCs和吸(xi)收劑物理(li)性質的差異進行分離。
含(han)VOCs的氣(qi)體(ti)(ti)自(zi)吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)塔(ta)底(di)部進(jin)(jin)入(ru)塔(ta)內(nei),在(zai)上升過程中與來自(zi)塔(ta)頂的吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)劑逆(ni)流接觸,凈化后(hou)(hou)的氣(qi)體(ti)(ti)由塔(ta)頂排出。吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)了VOCs的吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)劑通過熱交(jiao)換器后(hou)(hou),廢氣(qi)處理設(she)備進(jin)(jin)入(ru)汽提(ti)塔(ta)頂部,在(zai)溫(wen)度(du)高(gao)于吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)溫(wen)度(du)或壓力低于吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)壓力的條件(jian)下解吸(xi)(xi)(xi)。解吸(xi)(xi)(xi)后(hou)(hou)的吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)劑經(jing)過溶劑冷凝器冷凝后(hou)(hou)回(hui)到吸(xi)(xi)(xi)收(shou)(shou)(shou)(shou)塔(ta)。解吸(xi)(xi)(xi)出的VOCs氣(qi)體(ti)(ti)經(jing)過冷凝器、氣(qi)液(ye)分離器后(hou)(hou)以較純的VOCs氣(qi)體(ti)(ti)離開(kai)汽提(ti)塔(ta),被回(hui)收(shou)(shou)(shou)(shou)利(li)用。該工藝(yi)適合(he)于VOCs濃度(du)較高(gao)、溫(wen)度(du)較低的氣(qi)體(ti)(ti)凈化,其他情況下需要(yao)作(zuo)相應的工藝(yi)調整(zheng)。
固體表(biao)面吸(xi)(xi)附(fu)(fu)(fu)(fu)了吸(xi)(xi)附(fu)(fu)(fu)(fu)質(zhi)(zhi)后,一(yi)部(bu)被吸(xi)(xi)附(fu)(fu)(fu)(fu)的吸(xi)(xi)附(fu)(fu)(fu)(fu)質(zhi)(zhi)可從吸(xi)(xi)附(fu)(fu)(fu)(fu)劑表(biao)面脫離(li),此現附(fu)(fu)(fu)(fu)。而(er)當吸(xi)(xi)附(fu)(fu)(fu)(fu)進行一(yi)段時(shi)間后,由于表(biao)面吸(xi)(xi)附(fu)(fu)(fu)(fu)質(zhi)(zhi)的濃集,使其吸(xi)(xi)附(fu)(fu)(fu)(fu)能力(li)明顯下降而(er)吸(xi)(xi)附(fu)(fu)(fu)(fu)凈(jing)化的要求,此時(shi)需要采用一(yi)定的措施(shi)使吸(xi)(xi)附(fu)(fu)(fu)(fu)劑上已(yi)吸(xi)(xi)附(fu)(fu)(fu)(fu)的吸(xi)(xi)附(fu)(fu)(fu)(fu)質(zhi)(zhi)脫附(fu)(fu)(fu)(fu),以(yi)協的吸(xi)(xi)附(fu)(fu)(fu)(fu)能力(li),這(zhe)個(ge)過程(cheng)稱為吸(xi)(xi)附(fu)(fu)(fu)(fu)劑的再(zai)生。因此在實際吸(xi)(xi)附(fu)(fu)(fu)(fu)工程(cheng)中(zhong)(zhong),正是利用吸(xi)(xi)附(fu)(fu)(fu)(fu)一(yi)再(zai)生一(yi)再(zai)吸(xi)(xi)附(fu)(fu)(fu)(fu)的循環過程(cheng),達到除去廢氣中(zhong)(zhong)污染物質(zhi)(zhi)并回收廢氣中(zhong)(zhong)有用組分。