Circulating Fluidized Bed Gas-solid Flow Characteristics Of The Piv Test

This thesis is aimed to study the flow field in Circulating Fluidized Bed (CFB) holier in cold state based on the system of Particle Image Velocimetry (PIV), Several parts are included: the distribution of particles velocity in CFB boiler including radial velocity and axial velocity of particles; the average radial and axial concentration distribution of particles in CFB boiler; the average radial and axial size distribution of particles in CFB boiler.A critical review of the studying and application of the system of PIV used in CFB boiler are given in detail, the advantage of PFV used in CFB boiler is surveyed. Thinking of the character of flow field in CFB boiler, analysis about the requested experimental condition is done in detail.In this thesis, by changing the position of laser, increasing the operation velocity and adding the experimental materiel, the images data under the different operational condition are gotten. Visual analysis of the different area of flow field is done, using a serial of images about the typical sate of flow field.In this thesis, the basic arithmetic of PIV software - cross-correlation arithmetic is introduced in detail, During the data process, through processing the two sequential images by the cross-correlation arithmetic, the vector charts of particles velocity can be obtained, so is the chart of absolute velocity, with velocity decomposed into the radial velocity and axial velocity. In each small area, the velocity of particles is averaged, getting the charts of average velocity. In this thesis, the fields of velocity in the area near the wall and the core area are discussed in stress. Thinking about the fluctuate characters of flow in CFB boiler, the rules of particles flow is summarize according to macro analysis.Through the arithmetic of image process, the pretreatment of image, threshold processing, boundary finding, pattern recognition, the size and the numbers of particles can be gotten. By the statistic of data, the charts of average size and concentration of particles in the near wall and core area are obtained.hi the thesis, the problems in the course of experiment are summarized, including the localization of apparatus and the ways of image processing which result in data error. For dealing with the problems and shortcoming, some betterment advices and attempts of data process are put forward in the thesis.