加压O_2/CO_2气氛下煤粉着火特性的实验研究

Experimental Research on Ignition Characteristics of Pulverized Coal Under Pressurized O_2/CO_2 Atmosphere

研究了加压O2/CO2气氛下压力、氧浓度、煤焦结构和煤种等因素对大同烟煤和神火无烟煤着火特性的影响,并采用可燃性指数和综合燃烧特性指数评价不同压力下煤的着火和燃烧特性。加压热重实验结果表明,压力从0.1MPa升高至2MPa,着火温度先降低后升高,在1MPa下着火温度最低,燃烧特性最佳。在常压和加压条件下,提高氧浓度均可加快煤的着火。在常压下,随氧浓度提高,着火温度下降的幅度较小,但在加压时,较高氧浓度会改变着火模式,着火温度降低明显。扫描电镜分析显示加压促进煤在脱挥发分过程的破碎,提高碳氧反应速率,降低着火温度。煤的着火与煤种有关,挥发分含量较高的煤,其着火越容易。结果反映了加压富氧燃烧比常压富氧燃烧更有优越性。

The effects of pressure, oxygen concentration, char structure and coal types on the ignition characteristics of Datong bituminous coal and Shenhuo anthracite under pressurized O2/CO2 atmosphere were investigated, two combustion characteristic indexes were used to evaluate the coal ignition and combustion characteristics. The results of pressurized thermogravimetric experiments indicate that the ignition temperature decreases firstly and then increases with increasing pressure from 0.1 MPa to 2 MPa, and it is lowest at 1 MPa. Under atmospheric and pressurized conditions, the ignition temperature decreases with the increase of oxygen concentration. At atmospheric pressure, the decrease of the ignition temperature is slow with increasing oxygen concen- tration, while at elevated pressure, the decrease of the ignition temperature is significant at higher oxygen concentration along with the transformation of the ignition mechanism. The scanning electron microscopy （SEM） micrographs suggest that the elevated pressure enhances the coal fragmentation during devolatilization, thus more surfaces are available for reaction, the oxidation rate is improved, and the ignition temperature decreases. The decrease of the ignition temperature with the increase of volatile content indicates that coal types also affect the ignition of coal. The results show that the pressurized oxy-fuel combustion is superior to the atmospheric oxy-fuel combustion.