ABSTRACT
ABSTRACT: In order to improve the non-uniform cross-sectional local density distribution of catalysts in the conventional scheme of feed injection zone of FCC riser, a new type of feed injection scheme is proposed in which the feed jets realize a countercurrent contact with the catalysts. The local density distributions are obtained via a large-scale cold model. Three different setting angles of nozzles (the angle of the nozzle axis relative to the riser axis), 30o, 45o & 60o are investigated. Experimental results show that the influencing region of the feed jets shortens obviously above nozzles while extends below nozzles comparing with the conventional structure. In this type of scheme, the feed injection zone can be divided into three subzones, i. e. the upstream transition subzone, the jet controlling subzone and the downstream transition subzone. The lengths of the upstream and downstream transition subzones decrease if increasing the setting angle of feed nozzles.
