污泥-煤粉协同燃烧工艺中热解过程的特性研究

Characteristics of pyrolysis in sludge-coal co-combustion process

将干燥后的上海市生活污水处理厂污泥和蒙西烟煤煤粉分别按照5%∶95%,10%∶90%,30∶70%的质量比掺混,取(6.5±0.5)mg共混物利用热天平进行热重实验,升温速率为30℃/min,终温为800℃。选取干基污泥和干基煤粉质量比为30%∶70%的共混物在热裂解-气相色谱质谱联用仪(Py-GC/MS)上进行快速热解实验,研究了两者协同燃烧中污泥掺混对煤粉热解挥发分释放的影响。结果表明:污泥单独热解挥发分的主要释放峰集中在320℃,440℃与730℃,有别于煤粉单独热解挥发分的主要释放峰位置480℃和635℃。煤粉掺烧10%和30%比例的污泥后,600℃以下热解活化能明显降低;污泥掺烧比例越大,热解活化能降低越多。600℃以上热解活化能变化不大。700℃时掺烧污泥会生成更多的碳数为1~8的小分子气态有机物,这区别于煤粉或污泥单独热解的情况。污泥热解产物富含醇、酸、酯和酮,煤粉热解产物以碳氢化合物为主。掺混热解后,酯类产率降低,酸增多,酚类和烃类平均相对分子质量降低。这与污泥中灰的催化作用以及污泥为反应提供了H·和OH·有关,是600℃下活化能降低的主要原因。

Dried sludge and pulverized coal were mixed at mass ratio of 5%∶95%,10%∶90%,30%∶70%.(6.5±0.5)mg mixture was used to carry out thermogravimetric experiment in a thermogravimetry with heating rate 30℃/min and final temperature 800℃.The rapid pyrolysis experiment of mixture of 30%slude+70%coal(dry basis)was carried out in a pyrolysis gas chromatography and mass spectrometry(Py-GC/MS).The effect of sludge blending on the volatilization release of coal in the co-combustion process was studied.Following conclusions are obtained:1)the main release peaks of volatiles during sludge pyrolysis are at 320℃,440℃and 730℃,which are different from that of coal(480℃and 635℃);2)when the pulverized coal is mixed with 10%and 30%of sludge,the pyrolysis activation energy below 600℃decreases significantly.The larger the blending ratio,the more activation energy decreases.While,the pyrolysis activation energy above 600℃does not change obviously;3)at 700℃,the co-pyrolysis of coal and sludge can generate more small molecules of gaseous organic matter with carbon number 1-8,which is different from the pyrolysis of coal or sludge alone.4)the pyrolysis products of sludge are rich in alcohol,acid,ester and ketone.The pyrolysis products of coal are mainly hydrocarbon.During co-pyrolysis,the yield of ester decreases and the acid increases.The average molecular weight of phenols and hydrocarbons decreases.This is related to the catalytic effect of ash in sludge and the introduction of H·and OH·provided by sludge for the reaction.Meanwhile,this may also be the main reason for the decrease of activation energy below 600℃.