Multiphysics Coupling Analysis Of Large Vibrated Fluidized Bed

Vibrated Fluidized Bed (VFB) drying technology is one of the industrial drying methods and more and more widely used in recent years. With the enormous demand for industrial production, it shows a broad application prospect. However, two practical problems have long been clear during the application of VFB equipment. One problem is the contradiction between the existing equipment scale and production demand, and the demand for large equipment is increasing. The other problem is that complex and harsh working environment makes strength evaluation difficult as vibrated fluidized bed works in the multiphysics fields of flow, temperature and vibration.In order to solve the above two aspects of problems, this thesis completes the following work in view of large vibrated fluidized bed. Firstly, vibration parameters are calculated and the overall framework model is established due to the 150t/h large vibrating fluidized bed. Secondly, fluid-solid coupling heat transfer analysis about the above model is carried out using CFD to obtain the distribution of flow field and temperature field. Thirdly, thermal stress of the structure is analysed with the temperature distribution data loaded into the finite element model. Finally, dynamics analysis, such as modal, harmonic response and transient analysis, are conducted with the temperature and thermal stress loads to get the vibration characteristics at the working frequency. This thesis obtains the following results and conclusions.Through the analysis of the flow field and temperature field, the velocity of the flue gas is concentrated in the middle part of the bed body. The maximum velocity on the area of distributor is 13m/s and the average speed is 4.93m/s, which meet the demand of gas fluidization. The maximum temperature of the main structure is on the beams, which is 290℃. The position of reinforcement greatly affects the thermal stress distribution of the structure. After adjusting the position of reinforcement, the maximum thermal stress is effectively reduced to 244MPa and it occurs at the connections between the two lateral beams and side plates. The thermal expansion phenomenon makes that the bed expends 9.6mm along the X direction in maximum and the upper edge of the side plates expends 15.8mm totally along the Y direction. The first 15 natural frequencies are obtained through modal analysis, and it is proved that the structure avoids the resonance phenomenon at the working frequency. Through harmonic response analysis, the maximum stress is 253MPa when working at 15.5Hz, and the stress distribution has little difference from thermal stress, but the deformation is a little larger than the static analysis. The structure response of displacement, velocity and acceleration can be got from transient dynamic analysis. Displacement amplitude at the spring connecting is about 2mm, which meets the design requirement.The content of this thesis has great guiding significance in engineering design, optimization and strength evaluation of the large vibrated fluidized bed equipment.