钢厂烧结烟气高硫高尘SCR工艺受硫酸氢铵影响的分析与对策

将高硫高尘选择性催化还原（SCR）工艺应用于钢厂烧结烟气脱硝,分析了硫酸氢铵（ABS）的形成原因、影响因素及常规工艺控制,并提出了应对措施。研究结果表明,NH₃、SO₃和温度等是影响ABS生成的主要因素。最低连续喷氨温度应高于ABS分解温度且不低于310 ℃,可有效抑制ABS生成。根据数值模拟结果,在高温烟道至反应器入口的弯头处设置导流板可保证氨气均布。采用带前馈信号的串级控制模式调节喷氨量,控制催化剂吹灰器的时间频次,可有效防止催化剂失活和堵灰。工程实践结果显示,脱硝效率不低于94.1%,NO_x排放质量浓度不高于36.5 mg/Nm³,符合设计要求。

Analysis and countermeasure on effect of ammonium bisulfate on high sulfur and high dust SCR process for sintering flue gas in steel plant

The high sulfur and high dust selective catalytic reduction （SCR） process was applied for denitrification of sintering flue gas in steel plant. The formation reason of ammonium bisulfate （ABS）,influencing factors and conventional process control were analyzed,and the countermeasures were suggested. The research results show that NH₃,SO₃ and temperature are the main factors that affected the formation of ABS. The minimum continuous ammonia injection temperature should be higher than the decomposition temperature of ABS and no lower than 310 ℃,which can effectively inhibit ABS formation. According to the numerical simulation results,deflector plate at the elbow between high-temperature flue pipe and reactor inlet can ensure the uniform distribution of ammonia. Cascade control mode with feedforward signal is adopted for adjust the ammonia injection quantity and control the time frequency of catalyst soot blower,which can effectively prevent catalyst deactivation and ash plugging. The results of engineering practice show that the denitration efficiency is no less than 94.1%,the emission concentration of NO_x is no higher than 36.5 mg/Nm³,which meet the requirements of NO_x emission standard.