燃煤机组脱硝系统速度场与浓度场协同优化

Collaborative Optimization of Velocity Field and ConcentrationField of Coal-fired Unit Denitrification System

某300 MW火力发电机组超净排放过程中,存在深度调峰时机组效率降低、空气预热器堵塞、氨逃逸过高等问题。通过冷热态摸底实验对选择性催化还原(SCR)脱硝系统进口流场和出口截面氮氧化物(NO_(x))浓度进行评估诊断,提出系统高效运行的应用方案,采用计算流体力学(CFD)软件进行数值模拟,并且通过冷态物理模型对解决方案进行论证。工程实践应用结果表明:协同优化可以取得较好的烟气流动分布且维持脱硝系统较低的压降,第一层催化剂入口的速度相对标准偏差降低至10.79%,脱硝系统总压降小于600 Pa,供电煤耗率降低0.3 g/(kW ·h),具有较好的节能减排效益。

There were problems such as reduced unit efficiency, blocked air preheater and excessive ammonia escape during deep peak regulation in the ultra-clean emission process of a 300 MW thermal power generating unit. The cold and hot state mapping test was carried to evaluate and diagnose the inlet flow field and the NO_(x) concentration in outlet section of the selective catalytic reduction (SCR) denitrification system, and the application scheme for the efficient operation of the system was proposed. Computational fluid dynamics (CFD) software was used for numerical simulation, and the solution was demonstrated by cold state physical model. The results of engineering practice application show that, the collaborative optimization can achieve a good flue gas flow distribution and maintain a low pressure drop in the denitrification system. The velocity relative standard deviation of the catalyst inlet in the first layer is reduced to 10.79%, the total pressure drop of the denitrification system is less than 600 Pa, and the net coal consumption is reduced by 0.3 g/(kW ·h), which has better energy saving and emission reduction benefits.