REMOVAL TECHNOLGIES OF POLLUTANT GASES AND TOXIC HEAVY METALS BY FINE PARTICULATE SORBENTS

日本垃圾填埋场的减少导致了最终垃圾体积的减少。减少二恶英的排放引起高温燃烧或气化条件。同时，燃气轮机联合循环发电效率的提高也需要高温条件。然而，它的状况导致有毒金属的排放，影响人体健康。除非这些金属排放足以由烟气处理系统或带有热气体过滤器的粉尘分离过程控制，否则应减少燃气轮机的使用寿命。本研究的目的是利用细颗粒吸附剂在高温下捕获污染气体，如盐酸（HCl）和/或有毒重金属镉（Cd）。在第一步实验中，以碳酸钙氧化钙（CaO）为吸附剂的石灰石。HCl连续测量装置的结果表明，温度在750℃以上时，HCl转化为CaCl_2的速度加快，但在更高温度下，熔炼CaCl_2的速度明显下降。颗粒大小影响其熔融行为，即使在相同的反应温度下也会产生不同的转化率。当SO_2混合时，快速生成CaSO_4降低了HCl的转化率。与水一起，CaCl_2释放出HCl。说明燃料中水分含量是CaO捕获Cl的重要因素。第二步实验采用高岭石作为捕集剂。通过批量实验，我们已经证实了高岭石作为吸附Pb和Cd的吸附剂是非常有效的，而具有相似层状结构的高岭石也是有效的。本研究采用流动实验的方法，将Cd作为气溶胶蒸汽供给。结果表明，对于任何浓度的镉，两种高岭石过滤对镉的捕集率在40 min内均增加，在60 min时均下降。高岭石的产率最高可达40%左右，但似乎与浓度无关。相当于300μg镉对1.0g高岭石吸附剂的吸附作用。在60分钟内捕获率的下降可以解释为金属将吸附剂留在二氧化硅纸上并离开这些过滤器。在800℃下也得到了类似的结果。结果表明，除温度和时间外，烟气中金属浓度是一个重要的参数。此外，本报告还测量和描述了粒径和物理化学吸附的影响。少

Decrease of landfill place in Japan gives rise to decrease of volume of final waste. Reduction of the emission of dioxins causes high temperature combustion or gasification condition. Also, increase in efficiency by combined cycle power generation with gas turbine needs the high temperature condition. However, its condition causes the toxic metal emissions, which affect human health. Unless such metal emissions could be enough to controlled by flue gas treatment system or dust separation process with hot gas filters, the service life of the gas turbines should be decreased. Objectives of this research is to capture pollutant gases such as hydrochloric acid (HCl) and/or toxic heavy metals as cadmium (Cd) at high temperature by fine particulate sorbent. In first-step experiment focusing on HCl calcium oxide (CaO) of limestone was used as a sorbent. Results by a continuous measurement equipment for HCl showed that conversion of HCl into CaCl_2 is increased with temperature up to 750℃ but … More it is decreased at much higher temperature by melting CaCl_2. Particle size affects on its melting behavior and gives different conversion even at the same reaction temperature. When SO_2 is mixed, the conversion of HCl is decreased by fast formation of CaSO_4. With water, CaCl_2 emits HCl. It suggests that water content in fuel is an important factor to capture Cl by CaO.In second-step experiment on capturing Cd by minerals, kaolinite was used. We already confirmed that as candidates of sorbent to capture Pb and Cd kaolinite could be much effective and halloysite, dickite with similar layer structure are also effective by a batch experiment. In this study by using flow experiment, Cd was supplied as aerozol vapor. Results suggested that the capture yields of cadmium by both filtering of kaolinite are increased with time up to 40 min and decreased at 60 min for any concentration of cadmium. Kaolinite gave a maximum yield of around 40% but it appeared to be independent of the concentration. It is equivalent to the 300μg of cadmium to 1.0g of kaolinite sorbent. Decrease of captured yields at 60 min could be explained by metal leaving sorbent into silica paper and out of these filter. Similar results were also obtained at 800℃. It suggests that metal concentration in flue gases is one of more important parameters as well as temperature and time. Furthermore, effects of particle size and physical and chemical adsorption were measured and described in this report. Less