Development Of Particle Test System Based On Imaging Processing Technique And Study On Mixing Characteristic Of Particles In Pipe Fluidized Bed

In order to study the mixing characteristic of particles in fluidized bed, particle test system based on image processing technique was developed in this paper. Full field velocity distribution of particles in gas-solid fluidized bed was measured by processing images grabbed by CCD camera. Particle tracing algorithm based on cross-correlation method was also developed in this paper for the study of mixing behavior of particles in fluidized bed.Based on the analysis of image velocimetry theory, the feasibility of using image processing technique in velocity measurement of particles in fluidized bed was studied in this paper. Experiment shows that the system developed in this paper can be applied successfully in the measurement of velocity of particles in fluidized bed(with relative error less than 5%). The movement of particles in a pipe fluidized bed was studied in this thesis. The effect of gas velocity, bed height and distributor type on the moving of particles in pipe fluidized bed were also investigated and particles' internal circulating characteristic was also proposed. It was found in this paper that the best relative distance of blowpipes(distance of two pipes/diameter of pipe) in pipe fluidized bed is 2.9. The velocity distribution of particles near bubble was studied in this paper, good agreement was found by comparing the results get from numerical simulation and experiment.According to the imaging cross-correlation algorithm, a particle tracing method based on imaging processing technique was developed. Experiment shows that disadvantages of traditional tracing method such as low accuracy, hard for repetition and laborious experiment were greatly improved in this method. It was found by using imaging tracing algorithm that particles in wake were mainly drop from upside of the bubble. A model for particle updating in bubble's wake and bubbling unite mechanism were also proposed in this paper.Particle Residence Time Distribution(RTD) was widely applied in researches of mixing characteristic of fluidized bed. In this paper, a renovating RTD method was used in mixing research of particles in pipe fluidized bed. The effect of gas velocity, bed height and distributor type on mixing characteristic was also investigated. Experiments showed that mixing property in pipe fluidized bed withrelative distance of blowpipe equal to 3.2 is better than that of traditional platefluidized bed.At the end of this paper, bubbling behavior and particle cluster property in circulating fluidized bed was studied by using full field velocimetry based on image processing technique. The role of bubble in flow transition from bubbling to fast fluidization and particle cluster property in dilute phase was also investigated in this paper.