在用多孔性固體(ti)物質(zhi)處理(li)流體(ti)混合物時,流體(ti)中(zhong)的某一(yi)組分(fen)或某些組分(fen)可被吸(xi)表面并濃集其(qi)上,此現象(xiang)稱(cheng)為(wei)吸(xi)附(fu)(fu)(fu)。吸(xi)附(fu)(fu)(fu)處理(li)廢氣時,吸(xi)附(fu)(fu)(fu)的對象(xiang)是氣態污染物,氣固吸(xi)附(fu)(fu)(fu)。被吸(xi)附(fu)(fu)(fu)的氣體(ti)組分(fen)稱(cheng)為(wei)吸(xi)附(fu)(fu)(fu)質(zhi),多孔固體(ti)物質(zhi)稱(cheng)為(wei)吸(xi)附(fu)(fu)(fu)劑(ji)。
吸收(shou)法(fa)采(cai)用(yong)低揮(hui)發或不揮(hui)發性溶劑對VOCs進(jin)行吸收(shou),再(zai)利用(yong)VOCs和吸收(shou)劑物理性質的差異進(jin)行分離。
含VOCs的(de)氣體(ti)(ti)自吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)塔底(di)部進入(ru)(ru)塔內,在(zai)上升(sheng)過(guo)程中(zhong)與(yu)來自塔頂的(de)吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)劑(ji)逆流(liu)接觸,凈(jing)化后的(de)氣體(ti)(ti)由塔頂排出。吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)了(le)VOCs的(de)吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)劑(ji)通過(guo)熱(re)交換(huan)器(qi)(qi)后,廢(fei)氣處理(li)設備進入(ru)(ru)汽(qi)提塔頂部,在(zai)溫度高于(yu)(yu)吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)溫度或壓力低于(yu)(yu)吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)壓力的(de)條件下(xia)解吸(xi)(xi)。解吸(xi)(xi)后的(de)吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)劑(ji)經過(guo)溶(rong)劑(ji)冷(leng)凝(ning)器(qi)(qi)冷(leng)凝(ning)后回到吸(xi)(xi)收(shou)(shou)(shou)(shou)(shou)塔。解吸(xi)(xi)出的(de)VOCs氣體(ti)(ti)經過(guo)冷(leng)凝(ning)器(qi)(qi)、氣液分離器(qi)(qi)后以(yi)較純的(de)VOCs氣體(ti)(ti)離開(kai)汽(qi)提塔,被回收(shou)(shou)(shou)(shou)(shou)利用。該工(gong)藝適合于(yu)(yu)VOCs濃(nong)度較高、溫度較低的(de)氣體(ti)(ti)凈(jing)化,其他情(qing)況下(xia)需要作相(xiang)應的(de)工(gong)藝調整。
固體表面(mian)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)了(le)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)質后(hou),一部被吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)的吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)質可從吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)劑表面(mian)脫離(li),此現附(fu)(fu)(fu)(fu)。而當吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)進行一段時(shi)間后(hou),由于表面(mian)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)質的濃集,使其吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)能力(li)明顯下降而吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)凈(jing)化的要求,此時(shi)需要采用一定的措施使吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)劑上已(yi)吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)的吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)質脫附(fu)(fu)(fu)(fu),以協的吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)能力(li),這個過程稱為吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)劑的再生。因此在實際吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)工(gong)程中,正是利用吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)一再生一再吸(xi)(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)的循環過程,達到除去廢氣(qi)中污染物質并回收廢氣(qi)中有(you)用組(zu)分。