硫磺回收装置停工过程中尾气达标排放方案优化

Optimization of Exhaust Emission Standard Scheme in the Process of Sulfur Recovery Plant Shutdown

硫磺回收系统受设备腐蚀、工况及负荷的影响,经常出现计划与非计划停工。传统的硫磺回收装置停工方法难以使尾气达标排放,因此有必要优化目前的停工方法使其与现有严苛的环保要求相适应。提出将低流量酸性气热浸泡后切换至燃料气模式,吹硫工程中加大炉头氮气流量,并与尾气处理部分同时运行,同时结合CTS络合铁脱硫单元,严格控制过程气氧含量,严防加氢反应器床层飞温及使CTS单元循环溶液pH值稳定在8~9,延长停工吹硫时间,降低排放超标风险的同时降低催化剂床层残余固态硫含量。经2018年4月停工检修过程检验,能满足最新排放SO2≤100 mg/Nm^3(GB 31570-2015)要求,取得了良好的经济和环保效益。同时也为新《石油炼制工业污染物排放标准》的实施以及同类环保装置的停工过程降低SO2排放提供参考。

The sulfur recovery system is affected by corrosion,working conditions and load of the equipment,and there are often planned and unplanned shutdowns.It is difficult for traditional sulfur recovery plant to discharge exhaust under certain standard,so it is necessary to optimize the current shutdown method to meet the existing stringent environmental requirements.This paper proposes to switch the low-flow acid gas to the fuel gas mode sulfur purging project so as to increase the nitrogen flow of the furnace head,operate such switch simultaneously with the tail gas treatment part,and combine the CTS complex iron desulfurization unit.The gas oxygen content in the process was controlled strictly.The flying temperature of the bed layer of the hydrogenation reactor was prevented and the pH value of the circulating solution in CTS unit was stabilized at 8~9.The downtime for sulfur purging was extended to reduce the risk of excessive emission and the residual solid sulfur content of the catalyst bed.After being tested during the shutdown in April 2018,the optimized scheme could meet the latest emission requirements of SO2≤100mg/Nm3(GB31570-2015).Good economic and environmental benefits were achieved.Meanwhile,this provides reference for the implementation of the new Emission Standards for Petroleum Refining Industry and reduction of SO2 emissions during the shutdown process of similar environmental protection devices.