Gas streaming is the severe bypassing of gas that can occur in deep, bubbling fluidized beds. Gas bypassing consists of a large jet that precesses around the walls of the fluidized bed. The remainder of the bed is either defluidized or poorly fluidized. In some case, multiple gas jets can occur in the bed. This gas streaming phenomenon is not typically seen in small laboratory beds, as bed heights in the laboratory beds are usually not high enough to produce this behavior. This gas bypassing tends to be an issue for large pilot plants or commercial units where fixing the problem is more expensive.

To better understand the gas bypassing behavior in deep fluidized beds, tests were conducted in a 0.3 and 0.9 meter ID columns at varying bed heights and fines levels. In addition, a MP-PIC model, using Barracuda™ from Arena-Flow, was used to further examine the role and mechanism of gas bypassing in these fluidized beds. Details of possible mechanisms and possible techniques for detecting gas-bypassing are presented.