Development of Clean Utilization Technologies of Low-grade Coals Combined with Biomass

为了实现低品位煤的高效、清洁利用，生物质与煤共燃或共气化技术将有助于提高低品位煤的利用率。在这项研究中，三种实验，如生物燃料燃烧，使用电加热间歇式燃烧器，煤与生物质的共燃，使用电加热落管式炉，和煤或生物质的基本气化，使用熔盐气化炉，进行了。对于生物燃料燃烧，生物燃料的点火延迟和燃烧速率分别变得比煤燃料的点火延迟和燃烧速率更短和更快，因为生物燃料中的生物质起到点火触发器的作用。消石灰可以原位捕集烟气中产生的SO_2。在混燃实验中，生物质对劣质煤的着火和燃尽有促进作用。但掺烧过程中NO和N_2O的排放变化趋势与燃煤过程相似。与NOx相关的化学动力学模拟也可以解释实验获得的NOx行为的趋势。但非均相反应模式似乎影响N_2O的变化趋势。在生物质燃烧中，产生粒径小于2μm的细颗粒作为灰颗粒。然而，将生物质与煤一起燃烧，来自生物质的细颗粒在燃烧期间被来自煤的灰捕获。熔盐煤气化炉具有炉内脱硫、除尘和碳的催化作用。即使在相对低的温度下，气化器也可以在没有气体净化系统的情况下生产清洁的合成气。

In order to utilize low-grade coals efficiently and cleanly, technologies of co-combustion or co-gasification of coal with biomass will contribute to enhancing utilization of low-grade coals. In this study, three kinds of experiments such as a biobriquette combustion, using an electrically heated batch combustor, co-combustion of coal with biomass, using an electrically heated drop tube furnace, and fundamental gasification of coal or biomass, using a molten salt gasifier, were carried out. For the biobriquette combustion, the ignition lag and burning rate of the biobriquette becomes shorter and faster than that of the coal briquette, respectively, since the biomass in the biobriquette plays a role for a trigger of ignition. Slaked lime can capture in situ SO_2 produced from the briquette. In the co-combustion experiments, the biomass can enhance ignition and burnout of the low-grade coal during the co-combustion. But, trend of NO and N_2O emissions during the co-combustion is similar with that during the coal combustion. The chemical kinetic simulation relating to NOx can also explain the trend of NOx behaviors obtained experimentally. However, heterogeneous reaction scheme seems to affect the trend of N_2O. In the biomass combustion, fine particulates with the particle size of less than 2μm are produced as ash particles. Burning the biomass with the coal, however, the fine particulates from the biomass are captured by the ash from the coal during the combustion. The molten salt coal gasifier seems to have such functions as in-furnace desulfurization, dust collection and catalytic action of carbon. It may be possible for the gasifier to produce a clean synthesis gas without a gas cleaning-up system even at relatively low temperature.