基于数值模拟的低热值褐煤锅炉SOFA风配风优化研究

SOFA Air Distribution Optimization of a Low Heat Value Lignite Coal-fired Boiler Based on Numerical Simulation

为解决某670 MW八角切圆塔式锅炉燃用低热值褐煤时炉膛出口CO体积分数偏高、抽烟口结焦的问题,采用数值模拟与试验相结合的方法研究了SOFA风垂直摆角、SOFA风率和风速等参数对炉内温度场、O2体积分数、CO体积分数和NOx质量浓度的影响。结果表明:合理提高SOFA风速可以有效降低炉膛出口烟气温度,并减小炉膛出口CO体积分数;与工况1相比,在工况6下炉膛出口CO体积分数由0.291 2%减小至0.025 7%,炉膛出口烟气温度降低43 K,排烟温度降低6 K,炉膛出口NOx质量浓度基本不变,锅炉效率提高0.63%,标准煤耗降低约2 g/(kW·h)。

To solve the problems of high CO emission concentration at furnace outlet and coking at flue gas exhaust outlet existing in a 670 MW octagonal corner tangentially-fired tower boiler burning low calorific value lignite, numerical simulations and experimental tests were conducted to study the effects of the following factors on the in-furnace temperature field, and the O2, NOx and CO concentration distribution, such as the vertical swing angle of SOFA, the SOFA volume and the SOFA speed, etc. Results show that the increase of SOFA air velocity can effectively reduce the flue gas temperature and CO concentration at furnace outlet. Compared with case 1, the outlet CO concentration of the furnace in case 6 has been reduced from 0.291 2% to 0.025 7%, with a reduction of flue gas temperature at furnace outlet by 43 K, a reduction of exhaust gas temperature by 6 K, an increase of boiler efficiency by 0.63%, and a reduction of standard coal consumption by 2 g/(kW·h), while the NOx emission concentration basically keeps unchanged at furnace outlet.