天然气再燃降低燃煤电站锅炉NO_X的排放水平

DECREASE NO_X EMISSION OF BOILERS FROM COAL-BURNING POWER STATIONS BY GAS RE—BURNING

为了降低燃煤电站锅炉NOX的排放水平,利用主燃区煤已生成的NOX遇到再燃燃料在还原性气氛中产生的未完全燃烧中间产物HCN基团、NHi基团时会被还原为N2的燃料分级再燃技术,作为最为有效的炉内技术措施可以降低我国燃煤电站锅炉NOX的排放浓度.根据甲烷和两种合成煤气为再燃燃料对降低燃煤产生的NOX还原效果基本相同的试验结果,指出可利用部分天然气作为再燃燃料降低'西气东输'沿线城市及天然气产区现有燃煤电站锅炉NOX较高的排放浓度,把NOX的排放浓度控制在400 mg/m3或更低水平.同时,由于采用再燃技术后入炉燃煤所占热量可减少10%～15%,燃燃烧过程中所产生的SO2排放水平也得到降低,从而实现同时降低NOX和SO2排放量的双效目标,使我国日益严重的酸雨态势得以改善,实现环境效益与国民经济持续快速发展相互协调的目标.

To decrease NOx emission level of boilers from coal-burning power stations, taking the re-burning techniques by fuel classification, i. e. Nx, produced by coal in the main combustion area will be reduced into N2 when it encounters the un-complete burning mid-products of HCN and NHi basic groups produced by re-burning fuel in the reduction atmosphere, as the most effective measures, the NOx emission concentration of boilers from coal-burning power stations can be decreased. According to the experimental results that show the almost same reducing effect is obtained to use methane and another two synthetic gases as the re-burning fuel, it is suggested to use gas as re-burning fuel to decrease NOx emission concentration of boilers from coal-burning power stations and control the emission concentration to 400 mg/m3 or less, in the cities along the West - East Gas Transmission Pipeline and the gas producing areas. With re-burning techniques, coal contributed thermal value for the boiler decreases 10% - 15% and SO2 emission also drops. The dual targets to decrease NOx and SO2 emission are achieved at the same time, which will improve the severe acid-rain situation in China and reach the purpose of sustainable development, and coordination each other for environment ad economy.