Guizhi Qiu

Measurement strategy for rectangular electrical capacitance tomography sensor

To investigate the influence of the measurement strategy for the rectangular electrical capacitance tomography (ECT) sensor, a Finite Element Method (FEM) is utilized to create the model for simulation. The simulation was carried out using COMSOL Multiphysics{trade mark, serif} and Matlab{trade mark, serif}. The length-width ratio of the rectangular sensing area is 5. Twelve electrodes are evenly arranged surrounding the pipe. The covering ratio of the electrodes is 90%. The capacitances between different electrode pairs are calculated for a bar distribution. The air of the relative permittivity 1.0 and the material of the permittivity 3.0 are used for the calibration. The relative permittivity of the second phase is 3.0. The noise free and noise data are used for the image reconstruction using the Linear Back Projection (LBP). The measurement strategies with 1-, 2- and 4- electrode excitation are compared using the correlation coefficient. Preliminary results show that the measurement strategy with 2-ele...

Sparse representation in electrical resistance tomography based on extended sensitivity matrix

Electrical resistance tomography is a soft-field tomography technique, i.e. the electrical field is changed everywhere in the sensing area with the change of conductivity in any pixel. To improve the image quality, an extended sensitivity matrix is designed in this paper. The base conductivity elements in the extended sensitivity matrix are consisted of a series of blocks with different number of pixels at all possible locations in the sensing region. Based on the new sensitivity matrix, a sparse representation method is implemented to reconstruct the conductivity distribution of cross-sectional area. Simulation results show that the proposed method based on the extended sensitivity matrix can reconstruct the image with a high quality.

Monitoring solid flow in a circulating fluidised bed with external heat exchanger by electrical capacitance tomography

Two circular electrical capacitance tomography (ECT) sensors have been designed and used to monitor the solids flow in a cold circulating fluidised bed (CFB) with an external heat exchanger (EHE). The ECT sensors have eight electrodes and were mounted in the side tube and return tube above the EHE via pneumatically controlled loop seal respectively. Dynamics test with different process conditions are given. Image reconstruction results in the cross-sectional of the two tubes are compared and averaged measured signals are given. The results indicate that the solid flow can be controlled in the EHE based on ECT measurement.

Investigation of the gas-solid flows in a circulating fludisied bed with multi-cyclone separators by electrical capacitance tomography

To investigate the gas-solid flows in a circulating fluidised bed with multi-cyclone separators, a circular ECT sensor and rectangular ECT sensor are designed and used to measure the solids distribution in a cross-section in the inlet and standpipe of cyclone separator respectively. The rectangular ECT sensor has 12 electrodes with two in each shorter side and four in each longer side. The circular ECT sensor has 8 electrodes. For image reconstruction, sensitivity maps have been calculated using a simulation package, Maxwell from Ansoft. Dynamics test of CFB processes with different fluidisation velocity are given both in the inlet and downwards standpipe of the cyclone. ECT test results are given and analyzed and compared with pressure measurement results.