生物质与聚乙烯共气化过程含氮污染物生成特性数值模拟研究  

Numerical simulation on the generation characteristics of nitrogen-containing pollutants during co-gasification process of biomass and polyethylene

作　　者：许传昌 罗素韩 朱贤青 李俊[1,2] 朱恂[1,2] 廖强[1,2] XU Chuanchang;LUO Suhan;ZHU Xianqing;LI Jun;ZHU Xun;LIAO Qiang(Key Laboratory of Low-grade Energy Utilization Technologies and Systems,Ministry of Education,Chongqing University,Chongqing 400044,China;Institute of Engineering Thermophysics,School of Energy and Power Engineering,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学低品位能源利用技术及系统教育部重点实验室,重庆400044 [2]重庆大学能源与动力工程学院工程热物理研究所,重庆400044

出　　处：《能源环境保护》2024年第6期112-124,共13页Energy Environmental Protection

基　　金：国家自然科学基金重点资助项目(52236009);重庆市技术创新与应用发展重点资助项目(cstc2019jscx-gksbX0018)。

摘　　要：上吸式气化炉中生物质与聚乙烯共气化可有效提高气化合成气的产气热值与H_(2)产率,但在共气化过程中含氮污染物的生成与排放特性尚不清晰,有待进一步研究。因此,基于颗粒动理学理论和欧拉-欧拉方法构建了上吸式气化炉中气固流动与化学反应耦合的二维数理模型,探究了空气当量比(ER)、生物质与聚乙烯混合比和水蒸气与燃料比例(S/F)对含氮污染物生成的影响规律。结果表明,在生物质与聚乙烯共气化中,NH3和HCN主要来自生物质挥发分的热解反应,主要分布于气化炉的热解区与干燥区。NO主要来自焦炭的燃烧与气化反应,其含量在氧化区最高,但随后会与焦炭、CO和H_(2)等气体的还原反应而降低。随着空气当量比的增加,NO的含量由5.17 ppmv(百万分之一的体积比,下同)逐渐增加为50.10 ppmv,而其他含氮污染物如N2O、NH_(3)和HCN的含量则下降;增加水蒸气与燃料的比例可以导致NO含量由33.74 ppmv降低到0.95 ppmv,但会促进N_(2)O的生成。此外,聚乙烯的加入可有效降低生物质气化过程中含氮污染物的生成,并且共气化过程中生物质与聚乙烯之间的协同作用会进一步抑制含氮污染物NO、NH_(3)和HCN的生成。The co-gasification of biomass and polyethylene in an updraft gasifier can effectively increase the calorific value of the syngas and the H2 yield.However,the generation and emission characteristics of nitrogen-containing pollutants during the co-gasification process have not yet been fully understood.Therefore,this study constructed a two-dimensional mathematical model of gas-solid flow coupling with chemical reaction in updraft gasifier based on the particle dynamics theory and Euler-Euler method,and investigated the effects of air equivalence ratio(ER),the blending ratio of biomass and polyethylene,and steam-to-fuel ratio(S/F)on the generation characteristics of nitrogencontaining pollutants.The results showed that NH3 and HCN mainly came from the pyrolysis of biomass volatiles during the co-gasification process of biomass and polyethylene,and therefore they were mainly distributed in the pyrolysis zone and dry zone of the updraft gasifier.The generation of NO mainly came from the combustion and gasification reaction of char,and thus the oxidation zone had the highest NO content.NO then reacted with char,CO and H_(2),leading to the decrease of its content.With the increase of air equivalent ratio,the content of NO gradually increased from 5.17 ppmv to 50.1 ppmv,while the content of other nitrogen pollutants such as N_(2)O,NH_(3)and HCN decreased.Increasing the moisture vapor to fuel ratio reduced NO content from 33.74 ppmv to 0.95 ppmv,but promoted the generation of N_(2)O.The introduction of polyethylene could effectively reduce the generation of nitrogen-containing pollutants during biomass gasification,and the synergistic effect between biomass and polyethylene during co-gasification process could further inhibit the generation of nitrogencontaining pollutants such as NO,NH_(3)and HCN.

关 键 词：生物质与聚乙烯 上吸式固定床 含氮污染物 共气化 数值模拟 

分 类 号：X705[环境科学与工程—环境工程]