污泥与秸秆掺烧过程及污泥灰中重金属含量分析  

Co-combustion between sewage sludge and maize stover and content analysis of heavy metals in ash

作　　者：郭帅 于士祥 车德勇[1] 刘洪鹏[1] 孙佰仲[1] Guo Shuai;Yu Shixiang;Che Deyong;Liu Hongpeng;Sun Baizhong(School of Energy and Power Engineering,Northeast Electric Power University,Jilin 132012,China)

机构地区：[1]东北电力大学能源与动力工程学院,吉林132012

出　　处：《农业工程学报》2021年第12期207-214,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然青年科学基金资助项目(51806033);国家重点研发计划项目(2018YFB0905104);吉林省科技发展计划项目(20190201096JC)。

摘　　要：焚烧是处理污泥的一种有效方式,但处理过程中会产生重金属等污染物,若对焚烧后的污泥灰进行填埋等处理会污染土壤,因此降低污泥灰中重金属含量是亟待解决的问题。基于此,在一台实验室规模的管式炉中,研究了350~650℃下污泥与玉米秸秆的掺烧反应。主要目的是探究不同温度及秸秆掺混比对燃烧灰中8种重金属(Zn、Mn、Pb、Sb、As、Ni、Cr、Cu)含量的影响。结果表明:在试验工况下,随着秸秆的添加,灰中重金属Zn、Pb、Sb含量减少,350℃纯秸秆与纯污泥的燃烧灰相比3种重金属的含量分别降低了93%、90%及82%;在温度350~550℃下,Mn、Cr在掺烧灰中的含量比污泥或秸秆单独燃烧时高,350℃混烧灰中这两种重金属的含量分别比纯秸秆灰高出了20%及37%。而Ni、Cu的含量却相反,450℃掺烧灰中这两种重金属含量分别比纯秸秆灰中含量低了30%及50%。随后,借助XRD等测试手段探究了灰中重金属含量变化的原因。结果表明:秸秆灰中含有较多的KCl,350℃时高达45.4%,其通过化学反应转化为HCl,而后与重金属发生反应形成氯化物,促进重金属Zn、Pb、Sb的挥发。而掺烧灰中未发现KCl,这表明掺烧有助于KCl的转化,促进了Cu、Ni的挥发;同时,研究表明秸秆掺烧也有助于硅酸盐的分解,生成大量SiO2,其含量在650℃掺烧灰中可高达76.4%,这有助于Mn、Cr在掺烧灰中的保留。最后,基于试验数据利用多种函数拟合以建立混烧灰中重金属含量与反应条件间的关系,结果表明二者遵循Poly2D函数规律,进而可预测不同燃烧条件下秸秆与污泥掺烧灰中重金属的含量,从而对混烧灰的填埋风险进行评价。该研究可为污泥资源化处理提供技术支撑。Incineration is an alternative way to treat sludge,but heavy metals and other pollutants will be generated thereby.Besides,landfill of incinerated sludge ash will cause soil pollution,so reducing heavy metals in sludge combustion ash is an urgent problem to be solved.Based on this issue,this paper studies the co-combustion between sludge and maize stover at 350-650℃in a laboratory scale tubular furnace.The main purpose is to explore the influence of different reaction temperatures and mixing ratios of corn stalk on the content of eight heavy metals(Zn,Mn,Pb,Sb,As,Ni,Cr,Cu)in the(co-)combustion ash.The results showed that the content of Zn,Pb and Sb in the ash decreases with the addition of maize stover.Comparing with the combustion ash of corn stalk,the content of Zn,Pb and Sb within sludge combustion ash decrease by 93%,90%and 82%at 350℃.At 350-550℃,the content of Mn and Cr in the co-combustion ash is higher than that of sludge or maize stover ash alone.Comparing with the combustion ash of maize stover,the content of Mn and Sb within co-combustion ash decrease by 20%and 37%at 350℃.While the changing trend of Cu and Ni are just opposite.Comparing with the combustion ash of maize stover,the content of Cu and Ni within co-combustion ash decrease by 30%and 50%at 450℃.Then,it can be concluded from the testing results of XRD that the maize stover combustion ash contains more KCl(45.4%at 350℃),which could be converted to HCl under certain conditions,and then reacts with heavy metals to form chloride which promotes the volatilization of Zn,Pb and Sb.However,KCl is not found in the co-combustion ash,which indicates that complete conversion of KCl may occur during co-combustion,thus it could promote the volatilization of Cu and Ni.Meanwhile,it also shows that the decomposition of silicate to produce a large amount of SiO2(76.4%at 650℃)could happen during co-combustion,which is conducive to retention of Mn and Cr in the ash.Finally,the optimal fitting relationship(Ploy2D)between the contents of eight heavy me

关 键 词：污泥 重金属 玉米秸秆 掺烧 

分 类 号：TK6[动力工程及工程热物理—生物能]