O2/H2O气氛下煤粉恒温燃烧特性研究

Study on Isothermal Combustion Characteristics of Pulverized Coal in O2/H2O Atmosphere

利用恒温热重实验台,研究了O2/H2O气氛下水蒸气、氧气、氧水比、温度等对煤粉燃烧特性的影响。结果表明:相同氧气浓度下,提高水蒸气浓度导致燃尽时刻提前,影响程度随水蒸气浓度的增加而减弱;相同水蒸气浓度下,增大氧气浓度会加快煤粉燃烧,削弱焦炭与水蒸气的气化反应强度。当氧气与水蒸气浓度同时改变时,增大氧水比,燃尽时刻提前;焦炭最大燃烧速率与氧水比存在非单调关系,氧水比小于0.25时两者为负相关,此时焦炭最大燃烧速率出现时刻随氧水比增大而提前,氧水比大于0.25时呈正相关,焦炭最大燃烧速率出现时刻稳定在40s左右。温度升高,水蒸气的气化作用增强,燃烧速率增大;高浓度(80%)的水蒸气对不同煤种均可改善燃烧,煤阶越高改善效果越明显。

The combustion characteristics of pulverized coal in O2/H2O atmosphere were investigated by using an isothermal thermogravimetric equipment and the effects of water vapor,oxygen,oxygen-water ratio and experimental temperature were studied.The results show that under the same oxygen concentration,the burnout time is shortened with the increase of steam concentration and the promoting effect is gradually weakened.At some one steam concentration,increasing the oxygen concentration can strengthen the burning rate of pulverized coal but weaken the intensity of the gasification reaction.For the changing of oxygen and steam simultaneously,the burnout time is decreased as the oxygen to water ratio.However,the coke maximum combustion rate varied non-monotonic with the ratio of oxygen to water,when the oxygen to water ratio is less than 0.25,there is a negative correlation and the coke maximum combustion rate appears time becomes earlier with the increase of oxygen to water ratio.When the oxygen to water ratio is more than 0.25,there is a positive correlation and the coke maximum combustion rate appears time is stable at around 40 s.Moreover,with the increasing of temperature,the gasification reaction is enhanced.High concentration(80%)of steam can raise the burning rate of different coal,and the higher the coal rank,the effect of steam is more obvious.