提高蒸汽热裂解三烯收率最佳操作条件的模拟计算

Simulation of Operating Condition Optimization of Naphtha Steam Pyrolysis for Improving Olefin Yields

采用反应管入口总摩尔流率不变的汽/烃质量比调节方法,用管式裂解炉二维工艺数学模型在较宽的操作条件范围内对大庆石脑油蒸汽热裂解制乙烯、丙烯、丁二烯和三烯总收率进行了模拟计算,并对结果进行了正交分析。结果表明,汽/烃质量比调节方法可确保各个操作条件间无交互作用,说明了各调节参数的独立性和本模拟计算结果的可靠性。不同目的产物具有不同的最佳操作条件,以乙烯、丙烯、丁二烯和三烯总收率最大为目标时最佳裂解温度分别为1143、1103、1133和1143K。裂解深度主要取决于裂解温度,在裂解温度较低时停留时间和汽/烃质量比的作用较大,而在达到或大于最佳裂解温度后,两者的影响较小,应以高温、短停留时间来提高裂解反应的反应深度,汽/烃质量比的变化对提高目的产物的影响较小。

A two-dimensional mathematical model was used to simulate Daqing naphtha steam pyrolysis and analyze the effect of operation conditions on ethylene, propylene, butadiene yields and the sum yield of olefins. In the simulation, the steam/hydrocarbon mass ratio was adjusted with fixed molar flow rate of naphtha and steam. The orthogonal experimental design method was used to prove no interaction of operation conditions and the reliability of the simulation results. The results showed that the optimal operating conditions were never the same for different goals. The optimal temperature was 1143, 1103, 1133 and 1143 K for enhancement of ethylene, propylene, butadiene yields and total olefin yield, respectively. Cracking depth depended on the pyrolysis temperature. As naphtha didn＇t reach the maximum cracking depth, the effects of residence time and steam/hydrocarbon mass ratio were more. On the contrary, the effects of residence time and steam/hydrocarbon mass ratio were less. Therefore, the cracking depth could be enhanced by temperature rising and shortening residence time, while the effect of steam/hydrocarbon mass ratio was least.