660MW机组脱硝系统性能综合优化分析研究

Comprehensive Optimization of 660MW Unit Denitrification System Performance

目前电厂超低排放改造后脱硝系统运行控制难度加大,亟需脱硝系统优化试验进行运行指导,为电厂脱硝系统运行提供技术支持。以某660 MW火力发电厂脱硝系统为例,结合现场试验,考虑更多因素对脱硝系统性能进行了综合优化。分析结果表明:脱硝系统性能评价不仅要考虑脱硝效率,关注NO_x分布的相对标准偏差,调整温度分布均匀,保证了催化剂的使用时间;也需考虑脱硝系统出口氨逃逸浓度,优化喷氨量,以免造成二次污染,降低了空气预热器的换热效率;仍需关注SCR系统阻力,确保烟气有序流动,减少了系统阻力,防止了飞灰堆积;以及SO_2/SO_3转化率等综合指标,建议脱硝系统性能优化应综合考虑各个指标。

At present, it is more difficult to control the operation of denitrifieation system after ultra-low emis- sion transformation of power plant, so it is necessary to conduct the optimization test of denitrification system for operation guidance and provide technical support for the operation of denitration system in power plant. Based on the case study of the denitrification system of a 660 MW thermal, power plant, combined with the field experiment, the performance of denitration system was optimized by taking more factors into account. The analysis results show that the performance evaluation of denitrification system should be based on the com- prehensive factors： the denitrification efficiency, the relative standard deviation of NOx distribution, the even adjustment of temperature distribution to guarantee the catalyst duration, the ammonia escape concentration at denitrification system outlet, the amount optimization of ammonia spraying to avoid secondary pollution and re- duce the heat transfer efficiency of air preheater, the resistance of SCR system to ensure the orderly flow of smoke and reduce the system resistance and prevent the fly ash accumul.ation, as well as the comprehensive in- dexes such as SO2/SO3 conversion rate. It is suggested that it is more scientific to take the comprehensive fac- tors into account for the performance optimization of the denitration system.