水蒸气对煤粉燃烧生成NO的影响

THE INFLUENCE OF WATER VAPOR UPON FORMATION OF NO IN COMBUSTION OF PULVERIZED COAL

分别在不同温度（600℃-1 300℃）、不同氧气浓度（3%-21%）以及不同水蒸气量（0-12%）条件下,在固定床反应器中进行煤粉燃烧试验,研究水蒸气对煤粉燃烧生成NO的影响。研究结果表明：（1）4%的水蒸气加入空气中,当温度低于950℃时能抑制NO的生成,但会延长燃尽时间;当温度高于950℃时虽促进NO的生成,但能缩短燃尽时间。（2）在1 200℃条件下,4%的水蒸气加入混合气体中,当氧气浓度低于8.5%时既能抑制NO的生成,又能缩短燃尽时间;当氧气浓度高于8.5%时虽促进NO的生成,但能缩短燃尽时间。（3）在1 200℃和氧气浓度为3%条件下,NO生成量随水蒸气量的变化是先降低后升高,在水蒸气量为6%时NO生成量达到最低,各水蒸气量下都能缩短燃尽时间。因此,在高温低氧条件下,加入一定量的水蒸气能起到既抑制NO的生成又能加速煤粉燃烧的效果。

The tests of pulverized coal combustion have been carried out at different temperatures（600 ℃-1 300 ℃）,different oxygen concentrations（3%-21%）,and different water vapor volume（0%-12%） respectively in a fixed bed reactor,and the influence of water vapor upon formation of NO in combustion of pulverized coal being studied.Results of study show that as follows：（1） when water vapor of 4% is added into the air,formation of NO is suppressed at a temperature being lower than 950 ℃,but the time of burnout being extended,and the formation of NO being promoted at a temperature higher than 950 ℃,whereas the time of burnout being shortened;（2） at a temperature of 1 200 ℃ and with water vapor of 4% being added into the gas mixture,the formation of NO is suppressed at the oxygen concentration being lower than 8.5%,and the time of burnout can be shortened,and the formation of NO is promoted at an oxygen concentrition higher than 8.5%,whereas the time of burnout being also shorted;（3） at a temperature of 1 200 ℃ and oxygen concentration of 3%,the formation of NO decreases firstly along with the volume change of water vapor,and afterwards it increases along with the volume change of water vapor,and the minimum formation of NO is obtained at the volume of water vapor to be 6%,the time of burnout can be shortened at various volume of water vapor.Therefore,both low formation of NO and accelerated combustion of pulverized coal can be achieved with a certain amount of water vapor to be added under condition of both high temperature and low oxygen concentration.