关键词: 移动床, 锥面形挡板, 混合特性, 煤热解, 固体热载体

Abstract: To develop a step conversion process of coal pyrolysis/circulating fluidized bed (CFB) combustion, this paper focuses on realizing an optimal ash/coal mixing effect of moving bed within a limited height space of mixing section. A solid-solid cold mixing apparatus with adjustable cone shaped baffles inside was built and the mixing characteristics of particles were studied. Silica and quartz sand were used to simulate coal and circulating ash heat carrier from CFB, respectively. The influences of the material mixing ratio, the angle of baffles, the number and placement method (opposite and revolving) of baffles on mixing effect by using gravity mixing method were investigated, and the results were compared with those achieved by mechanical mixing. Mixing and dispersing coexist in the process of particles mixing. It was found that the more layers of 30°baffle by revolving placed, the more uniform of the silica and quartz mixture. The uniform mixture was obtained at the higher proportion of quartz sand to silica. Optimizing baffle structure and setting mode enhances convection mixing and shear mixing, which improves the solid-solid mixing effect obviously. Although the mixing effect of the cone shaped baffle is slightly worse compared with that of mechanical mixing, baffle mixing can still meet the requirements of the ash/coal mixing operation of coal pyrolysis with a solid heat carrier.

Key words: moving bed, cone shaped baffle, mixing characteristics, coal pyrolysis, solid heat carrier