基于分子动力学模拟的VOCs热氧化特性分析  

Analysis on thermal oxidation characteristics of VOCs based on molecular dynamics simulation

作　　者：汪林正 陆俞冰 张睿智[1] 罗永浩[1] WANG Linzheng;LU Yubing;ZHANG Ruizhi;LUO Yonghao(School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;School of Agriculture and Biology,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学热能工程研究所,上海200240 [2]上海交通大学农业与生物学院,上海200240

出　　处：《化工学报》2023年第8期3242-3255,共14页CIESC Journal

基　　金：上海市科委项目(20dz1205702);国家自然科学基金项目(51706139)。

摘　　要：采用反应分子动力学模拟的方法,选择苯、甲苯和苯乙烯作为代表性VOCs组分,分析其在不同温度下发生热解和氧化的反应特性,获得其总包动力学参数,并应用于VOCs在蓄热氧化装置(RTO)中的CFD模拟。芳烃类VOCs的初始热解步骤主要发生脱氢、脱侧链和开环反应,生成对应支链结构的小分子烃类和苯,而氧化过程则直接生成CO、H2O以及少量的烃类。不同VOCs的热解与氧化反应速率存在显著差异,动力学分析表明,使用一级反应假设适用于描述VOCs热解及氧化初始阶段的反应过程。CFD模拟表明,提高入口温度可以显著提升VOCs的转化效率,而在同等VOCs处理量的前提下,提高VOCs浓度、降低进口总流量,对VOCs转化效率的改善程度与提高入口温度相当,这表明VOCs浓缩技术耦合RTO更为高效节能。Benzene,toluene and styrene were selected as model compounds of representative volatile organic compounds(VOCs),and molecular dynamics(MD)simulation was adopted to attain their conversion characteristics during pyrolysis and oxidation processes under different temperatures.The global kinetic parameters of pyrolysis and oxidation reactions of VOCs model compounds were derived based on first-order reaction assumption,and the kinetic parameters were further used in computational fluid dynamics(CFD)simulation of regenerative thermal oxidation(RTO)system for abatement of VOCs.MD simulation revealed that at the initial stage of the pyrolysis process of aromatic VOCs,mainly dehydrogenation,side-chain cleavage and ring-opening would occur,forming small hydrocarbon species and benzene,while for the oxidation of VOCs,CO and H2O would be directly released accompanied by some light hydrocarbons.There are significant differences in the pyrolysis and oxidation reaction rates of different VOCs.Kinetic analysis shows that the first-order reaction assumption is suitable for describing the reaction process in the initial stage of VOCs pyrolysis and oxidation.Furthermore,CFD simulations suggested that temperature was crucial to improve the conversion efficiency of RTO,but simply elevating the temperature would require extra energy input.It was found that when dealing with the same amount of VOCs,it would be advantageous to use high-concentrated VOCs with lower flow rate,which could also improve the efficiency of the abatement of VOCs while saving energy.

关 键 词：挥发性有机物 蓄热氧化装置 分子模拟 反应动力学 计算流体力学 

分 类 号：TQ517.5[化学工程]