在用(yong)多孔性(xing)固(gu)體物(wu)質處理(li)流體混合物(wu)時,流體中的某(mou)(mou)一組(zu)分(fen)或某(mou)(mou)些組(zu)分(fen)可被吸表面并濃集(ji)其上,此現象稱(cheng)(cheng)為吸附。吸附處理(li)廢氣(qi)(qi)時,吸附的對象是氣(qi)(qi)態(tai)污染物(wu),氣(qi)(qi)固(gu)吸附。被吸附的氣(qi)(qi)體組(zu)分(fen)稱(cheng)(cheng)為吸附質,多孔固(gu)體物(wu)質稱(cheng)(cheng)為吸附劑(ji)。
吸收法采(cai)用低(di)揮發或(huo)不(bu)揮發性溶劑(ji)對VOCs進(jin)行吸收,再利用VOCs和吸收劑(ji)物理性質(zhi)的差異進(jin)行分離。
含VOCs的(de)(de)(de)氣(qi)體自吸(xi)(xi)收(shou)(shou)塔底部進入塔內(nei),在上升過程中與來自塔頂(ding)(ding)(ding)的(de)(de)(de)吸(xi)(xi)收(shou)(shou)劑逆(ni)流接觸(chu),凈化后(hou)的(de)(de)(de)氣(qi)體由塔頂(ding)(ding)(ding)排(pai)出(chu)。吸(xi)(xi)收(shou)(shou)了VOCs的(de)(de)(de)吸(xi)(xi)收(shou)(shou)劑通過熱交換器(qi)后(hou),廢氣(qi)處理設備進入汽(qi)提塔頂(ding)(ding)(ding)部,在溫度(du)高于(yu)吸(xi)(xi)收(shou)(shou)溫度(du)或壓力低(di)于(yu)吸(xi)(xi)收(shou)(shou)壓力的(de)(de)(de)條件下解吸(xi)(xi)。解吸(xi)(xi)后(hou)的(de)(de)(de)吸(xi)(xi)收(shou)(shou)劑經過溶劑冷(leng)凝(ning)器(qi)冷(leng)凝(ning)后(hou)回到吸(xi)(xi)收(shou)(shou)塔。解吸(xi)(xi)出(chu)的(de)(de)(de)VOCs氣(qi)體經過冷(leng)凝(ning)器(qi)、氣(qi)液(ye)分離器(qi)后(hou)以較純的(de)(de)(de)VOCs氣(qi)體離開汽(qi)提塔,被回收(shou)(shou)利用。該工(gong)藝適合于(yu)VOCs濃(nong)度(du)較高、溫度(du)較低(di)的(de)(de)(de)氣(qi)體凈化,其他情(qing)況下需(xu)要(yao)作相應的(de)(de)(de)工(gong)藝調整。
固體表面吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)了吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)后,一(yi)部被吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)的吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)可(ke)從吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)劑表面脫離,此現附(fu)(fu)(fu)(fu)(fu)(fu)(fu)。而當吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)進行一(yi)段時間(jian)后,由于表面吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)的濃(nong)集,使(shi)其吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)能力(li)明顯下降而吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)凈化的要求,此時需要采用(yong)一(yi)定的措施使(shi)吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)劑上已吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)的吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)質(zhi)(zhi)脫附(fu)(fu)(fu)(fu)(fu)(fu)(fu),以(yi)協的吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)能力(li),這個(ge)過程(cheng)稱為吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)劑的再生(sheng)。因此在實際吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)工(gong)程(cheng)中(zhong),正是利用(yong)吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)一(yi)再生(sheng)一(yi)再吸(xi)(xi)(xi)(xi)(xi)附(fu)(fu)(fu)(fu)(fu)(fu)(fu)的循環過程(cheng),達到除去廢氣(qi)中(zhong)污(wu)染物質(zhi)(zhi)并回收(shou)廢氣(qi)中(zhong)有用(yong)組(zu)分。