(384g) Effects of Gas Bypassing in Deep Beds On Cyclone Dipleg Operation

Cyclone diplegs play a major role in the functioning of fluidized beds. Previous studies have shown that at certain operating conditions there can be severe gas bypassing (also referred to as jet streaming) of gas in deep beds of Geldart Group A materials which leaves significant portions of the fluid bed to be defluidized or very poorly fluidized. If the cyclone diplegs are immersed in these defluidized regions, solids discharge from the dipleg may be hindered, which can lead to the flooding of the dipleg and the cyclone. This could result in high catalyst losses from the fluidized bed. The paper discusses tests conducted to demonstrate that the first stage diplegs can flood when discharging into a bed with gas bypassing. It also presents how the gas bypassing affects the operation of cyclone diplegs that have different terminations, e.g., splash plate, trickle valve. These tests were conducted in a 5-ft (1.52-m)-diameter semicircular column equipped with a Plexiglas faceplate to allow visual observation.