高氯原料加氢裂化装置产物热回收工艺方案的对比分析

Comparison and analysis of heat recovery systems for a hydrocracking unit processing feedstock with high chlorine-containing content

介绍了加氢裂化装置加工高氯原料常见的产物热回收工艺方案。以某石化加氢裂化装置为例,对热高低分和冷高低分2种流程进行模拟计算,对比分析模拟结果发现,冷高低分流程和热高低分流程均能满足高氯原料加工需求,前者需要在NH4Cl结盐温度以上设置间歇注水口,后者则需要在NH4Cl结盐温度以上设置热高分器及间歇注水口。从能耗角度考虑,最优工况下热高低分流程较冷高低分流程加热炉负荷低11.0%;与热高低分流程相比,冷高低分流程含硫液化气、干气收率较高,并且冷高分气氢纯度高,外甩高分气、外补新氢量均低于热高分流程;从注水洗盐效果来说,冷高低分流程注水量比热高低分流程多42.6%,循环氢系统酸性气浓度较低,但脱硫塔顶气酸性气浓度较高,相应需要增加防腐蚀措施。综合考虑认为热高低分流程更具有优势。

Common heat recovery schemes for hydrocracking unit processing high chlorine-containing feedstock are described.In a case study of certain hydrocracking unit,the simulation calculation is made for the hot high/low pressure separator and cold high/low pressure separator schemes.Results show both schemes can process high chlorine-containing feedstock with certain special design.The cold high/low pressure separator scheme needs only an intermittent water injection before NH4Cl decomposition,in contrast the hot high/low pressure separator scheme needs to set a hot high pressure separator in addition.In consideration of heat consumption,the load of heating furnace of hot high/low pressure separator scheme is 11.0%lower than that of cold high/low pressure separator scheme under the optimal conditions.In another aspect,the cold high/low pressure separator scheme can gain higher yield rates in both sulfur-containing liquefied petroleum gas and dry gas,and consumes less fresh hydrogen due to higher purity of hydrogen.From the aspect of water injection and salt solution,the cold high/low pressure separator scheme consumes 42.6%more desalting water than the hot high/low pressure separator scheme.A corrosion prevention measurement shall be adopted for the cold high/low pressure separator scheme because the concentration of acidic gases is higher in recycle hydrogen system but higher in acidic gas stripper.In a sum,hot high/low pressure separator scheme has more advantages.