乙烯裂解炉内燃烧、传热与裂解反应的模拟计算

NUMERICAL SIMULATION ON COMBUSTION,HEAT TRANSFER AND NAPHTHA PYROLYSIS REACTIONS IN ETHYLENE CRACKING FURNACE

为了揭示SL-Ⅱ型乙烯裂解炉炉膛内燃烧与其反应管内石脑油裂解反应历程，对炉膛内燃烧、传热与反应管内裂解反应进行了综合模拟计算，得到了炉膛内烟气速度、组分分布、烟气温度分布及反应管内裂解反应历程。应用非预混燃烧模型及DO辐射传热模型进行炉膛内燃烧、传热的计算；采用分子反应模型预测反应管内石脑油裂解反应的产品分布。结果表明，底部烧嘴的高速射流在炉膛下部产生回流区，对于炉膛下部烟气温度分布的均匀性至关重要；另外，烧嘴的高速射流引起炉膛内组分分布的较大变化，从而影响烟气温度分布。通过裂解产品及反应管壁温度模拟结果与烯烃厂测定数据的比较，证明了模拟计算的可行性，同时得出反应管壁高温区在管长的16～20m处。

To investigate the process of combustion in SL-Ⅱ cracking furnace and pyrolysis reaction of naphtha in tubular reactors, integrated numerical simulation on combustion, heat transfer and pyrolysis reactions was carried out and velocity, components concentration, and temperature distribution of flue gas and progress of pyrolysis reactions were obtained. Nonpremixed combustion model and DO radiation model were applied for computation of combustion and heat transfer in the furnace. Molecular reactions model was applied for pyrolysis reactions and predicting products yield. It was shown that the high velocity of bottom burners jet flow resulted in flue gas circumfluence, which played an important role in uniform of flue gas temperature in the bottom of the furnace. In addition, jet flow of bottom burners brought variation of components concentration and influenced temperature distribution of flue gas. Compared with measured data for products yield and temperature of tubeskin in olefin plant, the feasibility of simulation was indicated, and high temperature zone of tubeskin was located in 16-20 m along tubular reactor.