Simultaneous Measurements of Gas-Solid Flow Rates and Pressure Drop in Downcomer of J-Valve in CFB

T. Goshima and K. Terasaka

Abstract
To monitor the gas and solid streams in a downcomer of a J-valve in a CFB, the simultaneous measurement technique using the oxygen gas tracer, the hot particle tracer and the pressure drop was developed. By using this novel measurement technique, the dependence of the solid flow on the gas flow in the moving bed in the downcomer of J-valve was investigated. The pressure profile and the pressure balance in the J-valve as well as the CFB were measured. It was clarified that the circulating mass flux in a CFB or solid flow in a J-valve was governed by the pressure drop in the downcomer of the J-valve. The pressure drop in the downcomer of the J-valve was well estimated using the modified Ergun’s equation. To quantitatively control the circulating rate of the solid particles in the CFB, the monitor and tuning of the superficial gas velocity in the downcomer of the J-valve was important.

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Keywords
Flow measurement, tracer method, pressure drop, J-valve, circulating fluidized bed