SNCR(選(xuan)擇性非(fei)催化(hua)(hua)還原(yuan)(yuan)(yuan)法)脫硝技術,是(shi)一種經濟實用的NOx脫除(chu)技術,其(qi)原(yuan)(yuan)(yuan)理(li)是(shi)以NH3、尿(niao)素[CO(NH2)2]等作(zuo)為還原(yuan)(yuan)(yuan)劑(ji),在注(zhu)入(ru)到鍋爐之前霧化(hua)(hua)或者(zhe)注(zhu)入(ru)到鍋爐中(zhong)靠爐內(nei)的熱量蒸發霧化(hua)(hua)。在適宜的溫(wen)度范(fan)圍(wei)內(nei),氣相(xiang)的氨(an)或者(zhe)尿(niao)素就會(hui)分(fen)解為自由基(ji)NH3和NH2,在特定的溫(wen)度和氧存(cun)在的條件下,還原(yuan)(yuan)(yuan)劑(ji)與NOx的反(fan)應(ying)(ying)優(you)于(yu)于(yu)其(qi)他反(fan)應(ying)(ying)而進行。在較高(gao)的溫(wen)度范(fan)圍(wei)(850°C~1150°C) 內(nei),還原(yuan)(yuan)(yuan)劑(ji)(如氨(an)、CO或碳氫化(hua)(hua)合物等)有選(xuan)擇性地將煙氣中(zhong)的NOx還原(yuan)(yuan)(yuan)生成為N2和水來減少NOx排放(fang)的技術(shu)。
SNCR脫硝(xiao)系統組成(cheng)
SNCR脫硝系(xi)統(tong)(tong)(tong)主(zhu)要由(you)氨(an)(an)區(卸氨(an)(an)、儲氨(an)(an))、還(huan)原劑輸送系(xi)統(tong)(tong)(tong)、計量/分配系(xi)統(tong)(tong)(tong)、噴射系(xi)統(tong)(tong)(tong)、氣源站及其控制(zhi)系(xi)統(tong)(tong)(tong)等組成。
SNCR系統(tong)煙氣脫硝過程是由(you)下面四個基本過程完(wan)成:
卸料和儲存還原劑(ji);
在鍋爐合適位注入稀釋后的還原劑;
還原(yuan)劑的計量輸(shu)出(chu)、與水混合稀釋;
還原劑與煙氣混合(he)進行脫硝反應。