燃烧放热对准东煤成灰过程中钠盐释放的影响

Effect of combustion heat on release and transformation of the sodium during Zhundong coal ash-forming process

选取典型的准东煤五彩湾煤为研究对象,在马弗炉内制备400-1200℃的燃烧灰和再热灰,采用K型热电偶测量燃烧过程中样品表面温度,通过XRF、XRD分析获得灰的成分和结晶形式,取部分灰样逐级萃取,通过微波消解及电感耦合等离子体质谱仪(ICP-MS),获得灰中钠的赋存特性。结果表明,燃烧和再热灰在成分和晶体形式上差异显著,再热灰钠含量明显高于燃烧灰且灰熔点偏低;随着温度升高灰中钠盐总量明显减少,其中,水溶钠、醋酸铵溶钠迅速减少,而盐酸溶钠含量先增加后减少,不可溶钠增加,释放的钠以可溶钠为主;加热温度和时间影响钠的释放,燃烧反应放热导致煤粉表面温度超过环境温度200℃以上,是钠盐过多释放的主要原因。

As a typical Zhundong coal,Wucaiwan coal was chosen as the object of the investigation.The combustion ash with coal sample and the reheated ash with ashing sample at 400℃were prepared in a muffle furnace.K-type thermocouple was used to measure the temperature,XRF and XRD were used to investigate the composition of ash,and the sequential chemical extraction was used to examine the modes of occurrence of Sodium.The results show that the combustion ash and the reheated ash have marked differences in composition and melting points,sodium content in the reheated ash is higher than that in the combustion ash and the melting temperature of the reheated ash is lower than that in the combustion ash.With the increase of temperature,the total content of sodium decreases obviously,the water-soluble and ammonia-soluble sodium decreases rapidly,while the HCl soluble sodium increases first and then decreases and the insoluble sodium increases.The sodium released is mainly soluble.Heating temperature and time have an influence on the releasing of sodium,and the combustion reaction leads to the temperature on particle surface higher than surrounding temperature by 200℃,which is the main cause of releasing more sodium.