基于Aspen Plus的MSW气化熔融工艺全流程模拟研究

Whole process simulation of MSW gasification and melting system based on Aspen Plus

城市固体废物(MSW)气化熔融工艺能够减少二噁英的生成和熔融固化重金属,是一种清洁高效的固体废物处理方式。已有研究多针对MSW的热解特性以及污染物的生成与排放,而对气化熔融工艺系统模块之间的影响和各反应器间物质流、能量流的联动变化过程研究不足。利用Aspen Plus模拟平台,基于吉布斯自由能最小化原理,对MSW气化熔融工艺进行了全流程模拟研究,分析了垃圾干燥温度、垃圾含水率、气化温度、气化介质以及灰熔点对工艺流程节点参数、物质流和能量流的影响,并提出了优化的工艺流程和运行参数。结果表明:在垃圾热解模拟时,垃圾含水率为9%,通过烟气循环能达到能量自给;在相同条件下,以水蒸气作为气化介质的气化效率最高,且在气化温度为850℃,水蒸气当量比为50%时,达到最佳工艺效果;当气化后产生的焦炭在熔融炉内燃烧刚满足灰熔点温度时,灰熔点的升高使气化剂比例、气化气有效气体摩尔流量和碳转化率不断降低。不同工况下的物质流、能量流的变化对实际工程具有指导意义。

The gasification and melting process of municipal solid waste(MSW)can reduce the formation of dioxins and melt heavy metals,which is a clean and efficient solid waste treatment method.At present,most of the research is on the pyrolysis characteristics of MSW and the generation and emission of pollutants,while the research on the influence between the modules of the gasification and melting process system and the linkage change process of material flow and energy flow between each reactor is insufficient.The whole process simulation of MSW gasification and melting process was carried out by using Aspen Plus simulation platform based on Gibbs free energy minimization principle.The effects of waste drying temperature,waste moisture content,gasification temperature,gasification medium and ash melting point on the process node parameters,material flow and energy flow were analyzed,and the optimized process flow and operation parameters were proposed.The results showed that when the moisture content of garbage was 9%,the simulation of garbage pyrolysis could achieve energy selfsufficiency through flue gas circulation.Under the same conditions,different gasification agent media had the highest gasification efficiency using water vapor as the gasification medium,and the optimal process was achieved at a gasification temperature of 850℃and a water vapor equivalence ratio of 50%.When the char produced after gasification was burned in the melting furnace to meet the ash melting point temperature,the increase of ash melting point made the proportion of gasification agent,the effective gas molar flow of gasification gas and the carbon conversion rate decreased continuously.The changes of material flow and energy flow under different working conditions has guiding significance for practical engineering.