Investigation the Gas-Solids Distribution in a Large-Scale Circulating Fluidised Bed with Electrical Capacitance Tomography

The gas-solids hydrodynamic behaviour is one of the key issues to scale up a circulating fluidised bed (CFB) from small scale to large scale with multi-cyclone separators system. To investigate the solids distribution in a large scale CFB with six cyclone separators, electrical capacitance tomography is used to measure the solids concentration in the inlet and the standpipe of the cyclone. A rectangular ECT sensor has been designed and used to measure the solids distribution in a cross-section in the inlet of cyclone. Six circular ECT sensors with eight electrodes were mounted in the standpipe of the cyclone to measure the solid distribution among the six cyclone separator system. For image reconstruction, sensitivity maps have been calculated using a simulation package, Maxwell from Ansoft. Dynamic test with different fluidisation velocity and initial material load are given and analyzed. The preliminary test results show that the solids distribution of the cold model with axis-symmetrically or centre-symmetrically arrangement of cyclones can be measured in different bed inventories and superficial velocities. For the above two type of arrangement, the solid concentration in the six cyclones are different. In terms of uniform of gas and solid mass flow distribution, it is better in centre-symmetrically arrangement than axis-symmetrically arrangement.