中等挥发分烟煤回燃逆喷式燃烧数值模拟

为扩展逆喷室燃煤粉工业锅炉对中等挥发分烟煤的适用性,以大同烟煤为研究对象,利用数值模拟技术,对14 MW旋流逆喷式燃烧器三维建模,模拟了燃烧器内的燃烧组织过程。通过对比挥发分较高的神华煤模拟结果发现:着火位置、供料量和燃烧室温度均是影响中挥发分烟煤燃烧稳定的关键因素,延长高温区域、增加回流区域面积、强化燃烧器燃烧过程组织可有效提高燃烧器对中等挥发分煤种的燃烧效果,根据煤质特性,选择相应的运行条件可起到良好的稳定燃烧作用。结合现场运行,同时对现有燃烧器进行了优化研究,最终确定了14 MW燃烧器燃用大同煤的最佳运行工况,即一次风速为24 m/s、二次风速为10 m/s和进料量为0.35 kg/s的优化运行条件,经对运行过程检测,燃烧器出口和炉膛温度由原来的926.5℃和856.7℃分别升高至1 055.6℃和938.8℃,燃烧效率达到98%以上,燃烧更加稳定。

Numerical simulation on middle volatile coal combustion in reversed injection burner

In order to broaden middle volatile coal adaptability on the pulverized-coal industrial boiler system，the three-dimension model of the 14 MW reversed injection burner was built by using the Datong coal and the simulation technology.Compared the simulation results of Datong coal and Shenhua coal，the position of ignition，feed flow，temperature of combustor are the pivotal conditions of stable combustion，extending high-temperature area，increasing the area of recirculation zone and improving combustion performance，which could efficiently improve the combustion capability of the middle volatile coal.The optimum operating conditions which determined by characteristics of coal were also researched，the optimized operation conditions of the Datong coal were fix on at last，that is，the primary air speed 24 m/s，the secondary air speed 10 m/s，the feed flow 0.35 kg/s.By the industry testes，the outlet temperature of burner changes from 926.5 ℃ to 1 055.6 ℃；the temperature of boiler changes from 856.7 ℃ to 938.8 ℃ and combustion efficiency is up to 98%；the coal burning process are more steadily.