在用多(duo)孔(kong)性固體(ti)物質處理流體(ti)混合物時,流體(ti)中的某一(yi)組(zu)(zu)分或某些組(zu)(zu)分可被(bei)吸(xi)(xi)(xi)表面(mian)并濃(nong)集其上,此現象(xiang)稱(cheng)為吸(xi)(xi)(xi)附(fu)(fu)。吸(xi)(xi)(xi)附(fu)(fu)處理廢氣(qi)時,吸(xi)(xi)(xi)附(fu)(fu)的對象(xiang)是氣(qi)態污染物,氣(qi)固吸(xi)(xi)(xi)附(fu)(fu)。被(bei)吸(xi)(xi)(xi)附(fu)(fu)的氣(qi)體(ti)組(zu)(zu)分稱(cheng)為吸(xi)(xi)(xi)附(fu)(fu)質,多(duo)孔(kong)固體(ti)物質稱(cheng)為吸(xi)(xi)(xi)附(fu)(fu)劑。
吸收(shou)法(fa)采用(yong)低(di)揮發(fa)或不(bu)揮發(fa)性(xing)溶劑對VOCs進行吸收(shou),再(zai)利用(yong)VOCs和吸收(shou)劑物(wu)理性(xing)質(zhi)的差(cha)異進行分(fen)離。
含VOCs的(de)(de)(de)氣(qi)(qi)(qi)體自吸(xi)收(shou)(shou)(shou)(shou)塔底部(bu)進入(ru)塔內,在(zai)(zai)上升過程(cheng)中與來自塔頂(ding)(ding)的(de)(de)(de)吸(xi)收(shou)(shou)(shou)(shou)劑(ji)逆流接(jie)觸,凈(jing)化后(hou)(hou)的(de)(de)(de)氣(qi)(qi)(qi)體由(you)塔頂(ding)(ding)排出。吸(xi)收(shou)(shou)(shou)(shou)了VOCs的(de)(de)(de)吸(xi)收(shou)(shou)(shou)(shou)劑(ji)通過熱交(jiao)換器后(hou)(hou),廢氣(qi)(qi)(qi)處理設備進入(ru)汽提塔頂(ding)(ding)部(bu),在(zai)(zai)溫(wen)度(du)高于(yu)吸(xi)收(shou)(shou)(shou)(shou)溫(wen)度(du)或(huo)壓力(li)低(di)于(yu)吸(xi)收(shou)(shou)(shou)(shou)壓力(li)的(de)(de)(de)條件(jian)下解吸(xi)。解吸(xi)后(hou)(hou)的(de)(de)(de)吸(xi)收(shou)(shou)(shou)(shou)劑(ji)經過溶(rong)劑(ji)冷(leng)凝器冷(leng)凝后(hou)(hou)回到吸(xi)收(shou)(shou)(shou)(shou)塔。解吸(xi)出的(de)(de)(de)VOCs氣(qi)(qi)(qi)體經過冷(leng)凝器、氣(qi)(qi)(qi)液分離器后(hou)(hou)以較(jiao)純的(de)(de)(de)VOCs氣(qi)(qi)(qi)體離開汽提塔,被回收(shou)(shou)(shou)(shou)利(li)用。該工(gong)藝適合于(yu)VOCs濃度(du)較(jiao)高、溫(wen)度(du)較(jiao)低(di)的(de)(de)(de)氣(qi)(qi)(qi)體凈(jing)化,其他情況下需要作相(xiang)應的(de)(de)(de)工(gong)藝調整(zheng)。
固體表面吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)了(le)吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)質后,一部被吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)的(de)(de)吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)質可從吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)劑表面脫離,此現附(fu)。而當吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)進(jin)行一段時間(jian)后,由(you)于表面吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)質的(de)(de)濃(nong)集(ji),使(shi)其吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)能力(li)明顯下(xia)降而吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)凈化的(de)(de)要求,此時需要采(cai)用一定(ding)的(de)(de)措施使(shi)吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)劑上(shang)已(yi)吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)的(de)(de)吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)質脫附(fu),以協的(de)(de)吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)能力(li),這個過(guo)程稱(cheng)為吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)劑的(de)(de)再生。因此在(zai)實際吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)工(gong)程中,正(zheng)是利用吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)一再生一再吸(xi)(xi)(xi)(xi)(xi)(xi)(xi)附(fu)的(de)(de)循(xun)環過(guo)程,達到(dao)除去廢氣中污(wu)染物質并回收廢氣中有用組分。