Removal of Molten Slag Particles by a Packed Bed of Ceramic Balls under High Temperature

本研究提出了高温下煤渣颗粒捕集过滤器的新概念，将含熔渣颗粒的煤的高温燃烧气体引入陶瓷球（卵石）填充床中。在填充床中，熔渣颗粒被惯性冲击捕获，并以液态冷凝物的形式提取出来。为了证明该高温过滤器概念的技术可行性，进行了热模型实验。在这些实验中，将煤粉煤灰注入天然气的高温燃烧气体中，产生带有熔融渣颗粒的燃烧气体，并将这种燃烧气体引入由耐火材料组成的球床过滤器中。实验结果成功地证明了渣粒的连续捕获和提取没有堵塞的渣孔。同时，捕集效率高达97%，与常温下用油滴代替真实熔渣颗粒进行的冷模实验结果吻合较好。与该过滤器商业化概念相关的关键技术问题之一是卵石材料与熔渣接触的耐久性。为此，在电炉上进行了卵石材料抗熔渣耐久性试验。试验表明，当工作温度为1600℃或更低时，高纯氧化铝卵石具有良好的抗熔渣性能。最后，提出了将球床过滤与高温空气燃烧技术相结合的新型燃煤发电系统，是一种环保高效的发电系统。

In this research, a new concept of a filter for capturing coal slag particles under high temperature is proposed, where high temperature combustion gas of coal with molten slag particles is introduced into a packed bed of ceramic balls (pebbles). In the packed bed, molten slag particles are captured by the inertial impaction and are extracted as a liquid condensate.In order to demonstrate the technical feasibility of this high temperature filter concept, hot model experiments have been carried out. In these experiments, coal fly ash was injected into a high temperature combustion gas of natural gas to produce combustion gas with molten slag particles, and this combustion gas was introduced into a pebble bed filter composed of refractory materials. The experimental results have successfully demonstrated continuous capture and extraction of slag particles without clogging of the slag extraction hole. At the same time, it has been shown that capture efficiency as high as 97% is achievable, which well coincides with the cold model experiments performed under normal temperature using oil droplets instead of real molten slag particles.One of critical technical problems associated with commercialization of this filter concept is the durability of the pebble materials contacting with molten slag. Thus the durability test of pebble materials against molten slag was conducted using an electric furnace. This test has shown that high purity alumina pebbles show good resistance against molten slag if the operating temperature is 1600ﾟC or less.Finally, some new coal-fired power generation systems combining the pebble bed filter and the high temperature air combustion technologies are proposed, which are environmentally friendly high efficiency systems.