Solid circulation rate in recirculating fluidized bed

Recirculating fluidized bed (RCFB) is a spouted bed with a draft tube at th e center. This is used for a variety of operations such as incineration, co al and heavy crude oil gasification, grain drying, blending and mixing, etc . Solid circulation rate is an important parameter for any circulation syst em, and it describes the efficiency of operation. Mathematical models do no t always predict the circulation rates accurately. Hence, there is a need t o measure the circulation rates directly. Most of the methods (for direct m easurement) reported are either costly, involving high expertise and sophis ticated equipment, or time consuming. A butterfly valve arrangement can mea sure the solid circulation rate accurately and quickly. It is sturdy, and t he cost/expertise involvement is the bare minimum. Solid circulation rates measured directly using the butterfly valve arrangement are compared with t he solid circulation rates computed based on the particle velocity and the operating voidage in the downcomer bed. Solid circulation rates measured di rectly are in close comparison (mostly within a deviation of 10%) with the computed circulation rates.