水蒸汽对煤流化床富氧燃烧及SO_2析出和脱除的影响

为研究水蒸汽对煤燃烧的影响,以黄陵烟煤和晋城无烟煤为研究对象,在流化床多功能试验台上对比了水蒸汽加入前后煤的富氧燃烧性能,获得了水蒸汽对燃烧特性及SO2析出和石灰石脱硫特性的影响。结果表明:通过对流化床空气燃烧试验台架的简单改造即可实现煤在21%~40%富氧气氛下安全、稳定的燃烧。O2/CO2气氛下,随着O2体积分数的增加,炉膛温度上升,燃烧效率提高,SO2的析出量逐渐增加;石灰石脱硫由直接硫化转变为间接硫化,脱硫效率明显增大。水蒸汽对燃烧的影响更多的体现在水煤气反应等化学作用方面;水蒸汽加入后燃烧温度稍有降低,燃烧效率增加;SO2的析出量减小。此外,水蒸汽的加入明显促进了石灰石颗粒内部固态离子的扩散,石灰石的脱硫能力增强,尤其是在间接硫化时。

Effect of steam on coal combustion and SO2 emission and removal during oxy fuel fluidized bed combustion

In order to understand the effect of steam addition on coal combustion，SO2 emission and removal，a series of experiments of before and after steam addition were conducted under oxy fuel combustion conditions in fluidized bed (FB) using both Huangling bituminous and Jincheng anthracite as samples respectively.The results indicate that the safe and stable oxy fuel combustion of coal under 21%-40% O2 atmosphere is achieved by simple modification of the conventional air FB combustion test rig.With the increase of furnace height，the combustion temperature first increases and then decreases.Compared with air combustion，the combustion temperature and efficiency decline，the SO2 emission and limestone desulfurization efficiency are reduced during the coal combustion in 21%O2/79%CO2 atmosphere.In O2/CO2 atmosphere，with the O2 concentration increase，the combustion temperature and efficiency，and the SO2 emission all increase，the desulfurization efficiency increases obviously along with the transformation of sulfation reaction from direct sulfation to indirect sulfation.The effects of steam addition on coal combustion mostly represent chemical action by the water gas shift reaction.With the steam addition，the combustion temperature deceases，the combustion efficiency increases，and the SO2 emission is reduced.Furthermore，the steam addition promotes the solid state diffusion，the limestone desulfurization capacity enhances，especially in indirect sulfation.