Measurement of Gas-solid Flow Pattern in Rectangle Cross-section in CFB by Electrical Capacitance Tomography

摘要

The mal-distribution of solid suspension density in the circulating fluidized bed (CFB) boiler with parallel cyclones is a hot research topic recently. The measurement of gas-solid flow characteristics,including the solid concentration distribution and the velocity profile,is the key to understand such phoneme.Comparing with other measuring methods,such as PIV,LDV,y-ray attenuation technology, the electrical capacitance tomography (ECT) technology has the features of online monitoring,non-invasive,safe and economically.So far,in most of the studies with ECT measurements, the sensors have circular or square section,which can not measure the gas flow directly in the rectangle section commonly used in CFB boiler furnace. Based on the circular section sensor,by modifying the signal acquisition and image reconstruction,an ECT sensor with rectangular section and 8 electrodes was designed and manufactured,which was used to investigate the gas solid flow in a CFB riser with rectangle section (300mmx80mm).Meanwhile, the optical fiber probe was employed to measure the particle velocity and the thickness of boundary layer. The results prove that the ECT sensor with rectangle section can acquire the gas-solid flow characteristics.