鼓泡流化床内木屑成型颗粒混合化学链气化特性

木屑成型颗粒的大尺寸、非球形等特点,使其在流化床内的混合特性显著影响化学链气化中三相产物的分布。为研究成型颗粒流化及化学链气化特性,分别在冷态和热态工况下进行了颗粒混合实验和化学链气化实验,研究了不同流化速度下成型颗粒在轴向的浓度分布特性和三相产物组分分布规律。冷态混合实验表明：低流化速度下,成型颗粒浓度分布不均匀,在中上层形成堆积,流化速度适当增加,颗粒与床料混合更充分;热态气化工况中,在隔绝外部蒸汽的条件下,硫化气体体积流量的增加有利于颗粒与载氧体的接触,从而降低了焦炭产量,但缩短了挥发物的停留时间,三相产物中大分子焦油产量上升,合成气有效组分相应下降。

Performance of Mixing and Chemical Looping Gasification for Wood Pellets in a Bubbling Fluidized Bed

Due to the large size and non-spherical characteristics of wood pellets, the mixing characteristics of particles in fluidized bed significantly affect the output of three-phase products in chemical looping gasification. In order to study the fluidization and chemical looping gasification characteristics of biomass pellets, particle mixing and chemical looping gasification experiments were carried out under cold and hot conditions, respectively, and the concentration distribution of biomass pellets along the axial direction and the composition distribution of three-phase products at different flow rates were studied. The cold mixing experiments show that the concentration of particles is not uniform at low flow rates, of which particles accumulate in the upper part. When flow rates increase, particles and bed materials are mixed fully. Under the condition of thermal gasification, when the external steam is isolated, the increase of flow rates is beneficial to the contact between particles and oxygen carriers, thus reducing the char yield, but shortening the residence time of volatiles. The content of macromolecular tar in the three-phase products increases, and the effective component of syngas decreases accordingly.