有机危险废物在惰性气氛中热降解动力学特征

Thermal Degradation Kinetic Model of Organic Hazardous Waste in Inert Atmosphere

为研究有机危险废物在惰性或还原性高温工业窑炉（如炼铁高炉、炼焦炉、煤气化炉、煤液化炉等）中的协同处置效果,分别选择热稳定性在第1~2等级中的典型有机物——苯和氯乙烯,在氮气气氛高温管式炉进行热降解试验.将定量的气态苯或氯乙烯分别与氮气混合后通入高温管式炉中,采用GC-MS检测煅烧后尾气中苯和氯乙烯的浓度,以分析其热降解特性.结果表明：苯在500~1 100℃时热降解率（a）随温度（T）升高而快速增加,增幅达70%;在1 100℃以上时,苯热降解率缓慢增加,最终达到完全降解.氯乙烯在300~900℃时热降解率快速增加,增幅在55%左右,900℃以上热降解率增加缓慢直至完全降解.苯和氯乙烯的热降解率均随煅烧时间（t）增加而升高.苯和氯乙烯的热降解动力学模型分别为a=1-exp[-743.3exp（-12 930/T）t]和a=1-exp[-3.90exp（-4 307.8/T）t].通过苯的热降解动力学模型,可预测热稳定性高于氯乙烯的有机物的热降解率;而通过氯乙烯的热降解动力学模型,可预测比其热稳定性低的有机物的热降解率.

Thermal degradation experiments in nitrogen atmosphere in a tube furnace were conducted to study the results of co-processing organic hazardous wastes in high temperature and inert or reductive atmosphere industrial furnaces and boilers such as blast furnaces,coke ovens,coal gasification furnaces and liquefaction furnaces. Two typical organics,benzene and vinyl chloride,were selected from the first and second grades as the experimental reagents based on their thermal stability. Quantitative gaseous organic reagents benzene or vinyl chloride were mixed with nitrogen respectively,then passed through the high temperature tube furnace. The concentrations of benzene and vinyl chloride in the exhaust gas were measured by GC-MS to know the thermal degradation characteristics. The results showed that from500-1,100 ℃,the thermal degradation of benzene increased about 70% rapidly,while it increased slowly above 1,100 ℃ and was finally complete. The thermal degradation of vinyl chloride increased more than 50% rapidly from 300-900 ℃,and increased slowly above 900℃ and was finally complete. Increasing calcination time could improve the thermal degradations of benzene and vinyl chloride. The kinetic models of thermal degradations of benzene and vinyl chloride were obtained to simulate their degradation rules,and could be represented as： a = 1- exp[- 743. 3exp（- 12 930 /T） t] and a = 1- exp[- 3. 90exp（- 4 307. 8 /T） t],respectively. The thermal degradation kinetic model of benzene could be used to predict the thermal degradation of organic matter with a higher thermal stability than vinyl chloride. The thermal degradation kinetic model of vinyl chloride could predict the thermal degradation of organic matter with a lower thermal stability than vinyl chloride.