(442o) A Hydrodynamic Study in 2D Two Flow Regimes Fluidized Bed

Two flow regime fludized bed gasifier is adopted for low rank coal gasification. The gasification experiments have been researched for increasing the carbon conversion.

In this study, at two dimensional fluidized bed(2D fluidized bed), visualize the fluidized bed quality such as the flow pattern, bed height, bubble size and the pressure drop fluctuations in the transparent apparatus with the operating conditions such as the particle properties, initial inventory, and gas velocity. The fluidized bed phenomena is recorded by video camera. The fluidized bed height, bubble void fraction can be measured in each frame. And the results are compared with pressure drop fluctuations. The measurement parameters such as gas hold-up, bed expansion and bubble size distribution are represented with operating conditions.

The apparatus of 2D fluidized bed, is organized as follows. The thickness is 1 cm, the width of the lower part is 5 cm with 50 cm height and that of the upper part is 12 cm with 100 cm height, and the angle of the expansion part is 60 degree.

The minimum fluidizing velocity(umf) was measured by the relation between the pressure drop and the gas velocity. At increasing the loading amount, the particle is charged in the upper part as well as in the lower part. The total pressure drop between the lower part and the upper part will be increased even it lower part is at umf conditions, due to the upper part is below the umf conditions.

The pressure drop fluctuation response phenomena is analyzed with the gas velocity step change

The area of bubbles is measured in each pictures by the image analyzing. The relations among the gas velocity, bubble size distribution and the bed expansion are investigated. The flow pattern of the lower part and the upper part is determined by the pictures.