塑料焚烧过程中PAHs生成的动力学模拟

Kinetic simulation of PAHs formation during incineration of plastic

通过化学反应动力学机理,计算了塑料热解气在绝热燃烧反应体系中多环芳烃PAHs的生成情况。研究结果表明,在同样的反应温度下,随着燃烧摩尔比的增加,体系的反应不完全性加剧,同时PAHs生成峰值显著增加;在同样的燃烧摩尔比下,提高燃烧温度可以减小体系反应的不完全性,反应体系中PAHs生成峰值出现的时间均逐渐提前,同时其生成量也逐渐增大,随着反应温度的提高,生成PAHs的峰值幅度显著减小;在同样的反应体系温度和燃烧摩尔比下,纸张PAHs生成量比塑料和织物生成量小得多,而塑料和织物的PAHs生成量相当。

With the increasingly strictness of the pollutants emission limits, people have paid more and more attention to the polycyclic aromatic hydrocarbons （PAHs） formation during combustion process. Based on the analysis of PAHs formation mechanisms, including 101 gas species and 504 elemental reactions, the kinetic simulation of PAHs formation during gas phase combustion of the typical volatile matter from plastic pyrolysis usinge lementary reaction mechanisms was carded out in this work. rB is defined as the ratio of actual fuel/air to stoichiometric fuel/air. The simulation results show that with the increase of rB in combustion at same reaction temperature, the combustion becomes incomplete and the peak value of PAHs mole fraction goes up. Under the same value of rB in combustion, increasing combustion temperature can reduce the incomplete reaction, at the same time, the peak of PAHs appears early, and the peak value increases. In addition, the simulation results of three typical wastes at same conditions of rB and combustion reaction temperature show that the mole fractions of PAHs in the flue gas of paper combustion are less than those of plastic and fabric, and the yields of PAHs for plastic and fabric are almost the same.