关键词: 多产乙烯丙烯（MPE）, 组合进料, 导流筒, 循环流化床, 冷模

Abstract: A novel circulating fluidized bed riser featured by bottom enlargement and draft tube was investigated on a cold experimental apparatus with a riser of 8.1 m in height and bottom diameter of 120 mm and upper diameter 50 mm. The impact of operation conditions on axial and radial solid holdup and velocity in the novel riser was studied. Solid holdup and particle velocity distributions in the draft tube and the annulus were also investigated.  Experimental results showed that, compared with the traditional riser, multi-regime existed in the novel riser with a dense and radially homogeneous bed in bottom part and a dilute phase in upper part.  The draft tube was able to redistribute the solid particles coming from the inclined pipe. Huge differences of solid holdup and particle velocity in the draft tube and the annulus were observed. Due to the suction effect of the draft tube, solid particles tended to flow upward from the core region while flowed downward via the annulus in the riser bottom.

Key words: maximizing propylene and ethylene (MPE), combined feed, draft tube, circulating fluidized bed, cold model