两段流化床中半焦催化脱除焦油特性

摘要

针对新提出的流化床两段气化制清洁燃气工艺,利用小型流化床两段反应装置进行焦油脱除实验,比较了热裂解和半焦催化重整对焦油脱除的影响.研究发现,半焦对焦油的催化脱除与反应温度、气体在反应器中的停留时间及半焦的比表面积和孔结构密切相关,在实验操作范围内,随反应温度和停留时间的增加,焦油的脱除效率增加,生成更多的有效气体组分.使用半焦的比表面积越大、孔结构越发达,对煤焦油的催化脱除效果越好.与热裂解效果对比,半焦催化重整不仅能有效脱除焦油,提高有效气体组分的含量,且能明显抑制焦油脱除过程中的积炭生成.基于上述分析,适合流化床两段气化工艺的半焦催化脱除焦油条件为操作温度1000℃、气体在半焦床层中停留时间应该在0.9 s以上.%The fluidized bed (FB) two-stage gasification process has recently been proposed to produce clean fuel. Catalytic tar removal in a mini FB two-stage apparatus was studied by char catalytic reforming technique. It was found that tar removal was strongly related to reaction temperature, gas residence time in tar reformer, and char specific surface area and porous structure. In the range of experimental conditions, increasing reaction temperature and residence time effectively promoted catalytic reforming of tar and generated more useful gas components. Larger specific surface area and more advanced porous structures of char catalysts delivered better effects on catalytic tar removal. Compared to thermal cracking, char catalytic reforming of tar was more effective in tar removal, production of more useful gas components, and better inhabitation of carbon deposition. The study showed that the suitable operational condition for tar removal by char catalyst in FB two-stage gasification process was temperature of 1000℃ and gas residence time above 0.9 s.