超临界对冲燃烧锅炉低负荷运行及环保性能的模拟研究

Simulation research on low load operation and environment performance of supercritical opposite combustion boiler

为获得某电厂超临界对冲燃烧锅炉低负荷工况下的运行及环保性能,基于锅炉设计参数与现场试验数据,采用ANSYS Fluent软件对低负荷运行状态进行数值模拟研究,根据现场实际试验的情况控制燃烧器的投运方式、风速和风量等边界条件,模拟结果直观反映炉膛内的燃烧状态,并进一步对比25%和30%负荷工况的计算情况。结果表明,在25%负荷工况下,温度场及速度场表现均匀对称,整体稳燃性能优于30%负荷工况;30%负荷工况供风量大,O_(2)充足,CO浓度低于25%工况,但由于30%负荷工况多投运后墙中层燃烧器,对冲性能差,不仅容易造成前墙水冷壁超温,还会产生更多的NO_(x)堆积于前墙,出口的NO_(x)排放浓度为531.69 mg/m^(3),约为25%负荷工况的1.35倍。

Based on the design parameters and field test data of a supercritical opposed combustion boiler in a power plant,this paper uses ANSYS Fluent software to conduct numerical simulation research on the low-load operating state.According to the actual situation of the field test,the boundary conditions such as the operation mode of the burner,wind speed and air volume are controlled,and the simulation results directly reflect the combustion state in the furnace.After verifying the accuracy of the model,the calculation results of the 25%and 30%load conditions are further compared.The results show that the temperature field and velocity field are uniform and symmetrical under the 25%load condition,and the overall stable combustion performance is better than that of the 30%load condition.condition.In the 30%load condition,due to the more middle-level burners in the rear wall,the hedging performance is poor,which not only easily causes the overheating of the front wall water wall,but also produces more NO_(x)accumulation in the front wall,and the outlet NO_(x)emission in the 30%load condition The amount is about 1.35 times of the 25%load condition.