电站锅炉尿素SCR系统不同加热方法对能耗及脱硝率的影响

Influence of Different Heating Methods on Energy Consumption and Denitration Rate of Urea SCR System in a Utility Boiler

摘要: 燃煤锅炉排放的氮氧化物占据我国氮氧化物总排放量的半数以上，通过烟气净化技术对污染物合理控制有重要意义。本文基于唐山热电厂两台300 MW机组实施不同改造前后的运行数据，对电站SCR脱硝系统中两种不同尿素热解方式进行分析。比较了电加热系统SCR改造前后能耗变化情况，分析了电加热法热解喷氨和尿素直喷法系统的能耗与脱硝率差异。试验数据表明，两种热解方式的脱硝率均随负荷的增大而减小，电加热法脱硝率稳定性更高。系统能耗均随负荷增大而增大，负荷300 MW工况下，电加热法能耗较尿素直喷法高出3.3%；负荷150 MW工况下高出1.4%。通过比较分析，以期为燃煤电站运行经济性及尿素热解工艺选择提供参考。

Abstract: Nitrogen oxides emitted by coal-fired boilers account for more than half of the total emissions of nitrogen oxides in China. It is of great significance to reasonably control pollutants through flue gas purification technology. Based on the operation data of two 300 MW units in Tangshan Thermal Power Plant before and after the implementation of different transformation, this paper analyzes two different ways of urea pyrolysis in SCR denitration system of the power plant. The changes of energy consumption before and after SCR transformation of electric heating system were compared, and the differences of energy consumption and denitration rate between electric heating pyrolysis ammonia injection system and urea direct injection system were analyzed. The experimental data show that the denitration rates of the two pyrolysis methods are negatively correlated with the load, and the electric heating method is more stable. The energy consumption of electric heating method is 3.3% higher than that of urea direct injection method under 300 MW load; it is 1.4% higher than that under the condition of 150 MW. Through the comparative analysis, it is expected to provide reference for the operation economy of coal-fired power plant and the selection of urea pyrolysis process.