Flow characteristics in a horizontal liquid–solid circulating fluidized bed

Abstract

A horizontal liquid–solid circulating fluidized bed with a transparent single pipe is designed and built to investigate flow characteristics. The effects of the operating parameters, such as the fluid velocity, amount of added particles, particle types and pipe inner diameter on particle distribution and pressure drop in the horizontal test pipe, are systematically investigated by using the image measurement and acquisition system of a charge-coupled device (CCD) and a differential pressure transducer.Results show that the solid holdup increases with the increase in fluid velocity, amount of added particles and pipe inner diameter, but decreases with the increase in the sediment velocity of particle.The non-uniform degree decreases with the increase in fluid velocity, but fluctuates with the increase in the amount of added particles. The particles with small sediment velocity are fluidized and distributed better. The non-uniform degree increases initially and then decreases with the increase in pipe inner diameter.The pressure drop ratio is not always positive and decreases generally with the increase in fluid velocity, but fluctuates with the increase in the amount of added particles, the sediment velocity of particle and the pipe inner diameter. The amplitude and laws of fluctuation depend on particle types.The difference in pressure drop ratio decreases apparently with the increase in fluid velocity, but fluctuates slightly with the increase in the amount of added particles. The difference in pressure drop ratio generally decreases with the increase in pipe inner diameter.Phase diagrams are established to display the variation ranges of the operating parameters for particle distribution and pressure drop. The results can be used to select conditions for relatively uniform particle distribution in the horizontal circulating fluidized bed.