制约乙苯脱氢单元能耗的因素及对策

分析了海南实华嘉盛化工有限公司乙苯脱氢单元能耗高的主要原因,包括乙苯过热器内漏、蒸汽过热炉排烟温度过高以及空冷系统冷却能力不足等。针对存在的问题,分别提出了蒸汽过热炉增设空气预热器、乙苯过热器及膨胀节整体更换、空冷系统增加两台风机以及增设脱氢尾气深冷器等相应的改造措施。改造实施后,彻底解决了制约苯乙烯产量的乙苯过热器内漏问题,单这一项就可年增产苯乙烯8 800 t,同时也很好地解决了蒸汽过热炉排烟温度过高和空冷系统冷却能力不足等问题,使得脱氢尾气系统堵塞风险大幅降低。几项改造措施使蒸汽过热炉的排烟温度大幅降低,热效率有效提升,加热炉燃料气用量降低25 kg/h,脱氢尾气压缩机的3.5 MPa蒸汽用量下降1 000 kg/h,装置单位产品综合能耗下降1 815.8 MJ/t,节能效果显著。

Factors affecting energy consumption of ethyl benzene dehydrogenation unit

The root causes of high energy consumption of ethyl benzene dehydrogenation unit were analyzed,including internal leaking of ethyl benzene super heater,excessive high flue gas emission temperature of steam super heater and insufficient cooling capacity of air cooling system.To solve these problems,effective revamping measures were proposed such as addition of air preheater for steam super heater,replacement of ethyl benzene super heater and expansion joints,additional installations of two air coolers and installation of deep air coolers for dehydrogenation tail gas,etc.After implementation of these measures,the problem of internal leaking of ethyl benzene super heater which limits the ethyl benzene production has been solved.The annual production of ethyl benzene is increased by 8 800 tons.In addition,the problems of high flue gas emission temperature of steam super heater and insufficient cooling capacity of air cooling system have been solved,which has greatly reduced the risk of blocking in dehydrogenation tail gas system.The revamping measures will greatly lower the temperature of flue gas emission of steam super heater and effectively raise the thermal efficiency.The fuel gas for the fired heaters can be lowered by 25 kg/h,the consumption of 3.5 MPa steam for dehydrogenation tail gas compressor is reduced by 1 000 kg/h,the energy consumption of unit product is lowered by 1 815.8 MJ/t and energy saving is significant.