苯乙烯生产工艺的节能优化和经济分析

Energy-saving optimization and economic analysis of styrene production process

在中石化自主研发的苯乙烯生产工艺中,乙苯脱氢反应需要加入大量过热蒸汽作为脱氢介质,水蒸气和乙苯流量的比值是影响脱氢反应的一个重要因素。随着低水比催化剂工业应用取得进展,可以减少进入反应器的蒸汽量,而降低水比的关键就在于减少乙苯/苯乙烯塔顶冷凝器共沸蒸出的乙苯和蒸汽的量。控制恒沸蒸发量后,会导致乙苯/苯乙烯塔塔顶物料携带的热量不能完全回收。为合理利用这部分热量,对原工艺流程进行优化、热量进行耦合。此次节能优化主要涉及9台换热器,其中2台为新增。优化过程中还降低了预分塔塔压,提高了尾气压缩机出口温度。经过优化,可减少综合能耗11.364 kg标油(以1 t苯乙烯计),静态投资回收期约为2个月。

In the styrene production process self-developed by the Sinopec,the dehydrogenation of ethylbenzene requires a large amount of superheated steam as the dehydrogenation medium.The ratio of the steam to ethylbenzene flow rate is an important factor affecting the dehydrogenation reaction.With the industrial application of the low water ratio catalysts,the amount of the steam entering the reactor can be reduced.The key to reducing the water ratio is to reduce the azeotropic distillation of the ethylbenzene and steam from the top condenser of the ethylbenzene/styrene tower.After controlling the azeotropic evaporation,the heat carried by the top flow of the ethylbenzene/styrene tower cannot be fully recovered.In order to make reasonable use of the heat,the process was optimized and the heat was copled.The energy-saving optimization mainly involved 9 heat exchangers,of which 2 were added.In the optimization,the pressure of the pre separation tower was also reduced and the outlet temperature of the tail gas compressor increased.After optimizing,the integrated energy consumption can be reduced by 11.364 kg standard oil per ton styrene,and the static investment payback period is about 2 months.