Hydrodynamics of a Spouted Bed with a Porous Draft Tube

Abstract

The flow rate of the gas in the annular section, the particle circulation rate, the pressure drop and the particle hold-up in the tube section were measured for a spouted bed fitted with a porous draft tube. The results were more or less different from the data of a spouted bed fitted with a conventional (solid) draft tube.
The experimental relationships between the items as described above and the design factors of distance of entrainment zone and its diameter, and operating factors such as the gas velocity and the particle diameter were determined. A correlation concerning the particle circulation rate was presented in the operating region where the particle circulation rate increased in proportion to the gas velocity.
In addition, three patterns of particle flow in both porous and solid draft tubes were recognized by determining the pressure drops and the particle hold-up in the tube. These three patterns could be described as follows : a stable spouting region in which the particle hold-up was insensitive to the gas velocity ; a pulsing spouting region in which the particle hold-up varied with the gas velocity ; and a clogging region within the tube.