亚临界W火焰锅炉磨煤机组合运行方式优化数值模拟

Optimal Simulation on Coal Mill Combination Modes of a Subcritical W-shape Boiler

在不同磨煤机组合运行方式下对一台600 MW亚临界W火焰锅炉炉内流动、燃烧、传热及NOx排放特性进行了数值模拟,并与实测结果进行了对比.结果表明:不同磨煤机组合运行方式对煤粉颗粒在炉内的燃烧、平均停留时间、燃尽率、NOx排放特性及侧墙壁面附近温度分布等均有不同的影响;在兼顾燃烧效率、大屏过热器入口截面烟气温度和飞灰含碳量的同时,相比于6台磨煤机同时运行,5台磨煤机组合运行、停运靠近侧墙磨煤机的方式有利于降低NOx的排放质量浓度,达到了减排目的,同时下炉膛翼墙及侧墙区域结渣程度明显减轻.

Numerical simulations were conducted to in-furnace flow, combustion, heat transfer and NOx e- mission characteristics of a 600 MW subcritical W-shape boiler under different coal mill combination modes, so as to compare the simulation results with actual data. Results show that different coal mill com- bination modes have different effects on the combustion, average residence time of coal particles, burnout rate, NOx emission and temperature distribution near the side walls. In considering the combustion effi- ciency, the average flue gas at the inlet of the platen superheater and the carbon content in fly ash, the mode with six mills in service is superior to that with five mills in service one mill near the side wall out of service in the reduction of NOx emission, in which case the tendency of slagging near the side walls in low- er furnace would be reduced obviously.