Dynamic Analysis Of Vibration Fluidized Bed Based On Thermal-mechanical Coupling

The coal rank of lignite is relatively low. Reserve of lignite is large, which accounts for about 40% of the total global coal reserves. With the worldwide non-renewable energy consumption, especially the decline of high quality coal reserves, people’s attentions are attracted to lignite again. However, lignite has some features such as high water content, high volatile, and liable to spontaneous combustion, which will cause a huge waste even unnecessary danger during combustion, transportation, and storage. In order to expand the use of lignite, upgrading treatment for lignite is an essential process. According to the existing domestic and international studies on Lignite Pyrolysis Mechanism, the pyrolysis temperature of lignite is at 450℃-600℃. Using vibration fluidized bed to upgrade the lignite is a new technology. Therefore, vibration fluidized bed under high temperature will be effected by periodic vibration and shocks of materials. In this paper, coupling analysis of temperature field and stress field will be conducted on an example of vibration fluidized bed working at 600℃.Related research will be conducted on the following aspects in this paper:First, according to the traditional theory of vibration, mathematical model of the vibration fluidized bed is established. Pro/E software is used to establish a three-dimensional model of vibration fluidized bed. Then a simplified model of vibration fluidized bed is established in ANSYS. Second, temperature field is analyzed for the insulation layer of vibration fluidized bed. The insulation temperature distribution of insulation layer is obtained. Vibration fluidized bed temperature distribution is obtained by adding insulation temperature distribution to the vibration fluidized bed as a boundary condition. Thermal stress of vibration fluidized bed is obtained by Indirect Coupling Analysis Method under the condition of no Centrifugal force. Finally, the thermal stress is loaded into vibration fluidized bed as prestress. Vibration fluidized bed is analyzed through Block Lanczos Method. The top fifteen natural frequencies and mode shapes of vibration fluidized bed are obtained. The harmonic of vibration fluidized bed is analyzed by Complete Method based on the modal analysis of vibration fluidized bed. Amplitude of vibration fluidized bed is obtained under the condition of 0-15Hz frequency, considering the working frequency is at 12.5Hz,Through the analysis above, vibration fluidized bed temperature distribution is obtained, and the maximum temperature difference is 510℃. Then, thermal stress distribution of vibration fluidized bed is obtained. The maximum stress is in the contact area between frames and beams. The top fifteen modal natural frequencies and mode shapes of vibration fluidized bed are obtained in the coupled state. And the side plates are prone to deform. By harmonic response analysis, the maximum amplitude occurs at about 3Hz. Therefore,3Hz area needs to be rapidly passed through the use of Frequency Modulation Method in project. The study in this paper will have some guiding significance to the design of vibration fluidized bed at high temperature.