Effect of Different Nozzle Arrangements on Gas–solid Flow Characteristics of a New Air Distribution System Circulating Fluidized Bed

ABSTRACT

The air distribution system was one of the key devices that affects solid flow characteristics in circulating fluidized bed (CFB). Different air distribution systems have an influence on gas–solid flow uniformity, solids velocity, and concentration. In the conventional CFB, the air distribution system which composed of air chamber and distributor was placed on the bottom of the reactor. In this paper, an atmospheric circulating fluidized bed gasifier (AT-CFBG) was examined. The chamber and distributor of CFB was canceled and which was replaced by six nozzles with asymmetrical and symmetrical arrangement that mounted on the bottom of the furnace. A cold test was established at a scale of 1:15, the optical fiber was used to measure solids concentrations and velocities in the furnace under the asymmetrical and the symmetrical arrangement. The results showed that the asymmetrical arrangement has a better uniform velocity profile and has a higher solids concentration than those of the symmetrical arrangement. And it also has a stable solids circulation and a higher solids circulation rate (0.37 kg/h) than those of the symmetrical arrangement (0.34 kg/h).

KEYWORDS:

• Circulating fluidized bed
• air distribution system
• solids velocity
• optical fiber probe

Highlights

1. Different nozzle arrangements of NAS-CFB were investigated on a cold test bench

2. The solids velocities and concentrations in the furnace were measured by the optical fiber probe

3. The solids circulating rate were studied under the asymmetrical and the symmetrical arrangements

4. Pressure profiles with the asymmetrical and symmetrical arrangement were discussed

Additional information

Funding

This work was supported by National Key Research and Development Program of China [Grant No. 2017YFC0212502].