Modeling And Simulation Of Vibration Fluidized Bed Drying Process For Ceramic Particles

The energy consumption and pollution of ceramic industry is very high, which are reflected in the production of ceramic powder, baking and other links. With the vigorous implementation of national strategy for energy conservation, the development of new energy-saving dry granulation technology that could prepare ceramic particle is imperative. This technology could save more energy and would have more important applications in the ceramic industry than the existing sprayed drying. Vibration fluidized bed drying is an important operating unit that exists in the production line of ceramic powder dry granulation. However, the quantitative description and characterization and optimization of control about the process of ceramic particles vibration fluidized bed could not be got by the existing drying mechanism model for its drying mechanism is very complex and ceramic particles have many physical parameters.In the task, the ceramic particles vibration fluidized bed drying process is a subject of study. Using the two-fluid model to describe the flow characteristics of hot air phase and ceramic particles phase in the drying process with mathematical method, which is combined with the material characteristics experimental of ceramic particles and based on computational fluid dynamics(CFD). Then derived respectively the equations of heat and mass transfer of air-solid two-phase in the constant-rate drying period and the falling-rate drying period during the vibration fluidized bed drying (VFBD) process. The unsteady axisymmetric two-dimensional mathematical models of VFBD process were established finally, which is made up of the basic control equations and particle kinetic model and turbulence model and drag force model and heat and mass transfer model of gas-solid and other components. At last, the turbulent motion and heat and mass transfer process of two-phase is described quantificationally in the ceramic particles vibration fluidized bed drying process.Using the finite volume method to discrete and numerical calculate the control equations of VFBD process, then using the SIMPLE algorithm to numerical iterative solve the two-fluid model. Using C language to compile the vibration model of VFBD, then introducing it to the Fluent solver through the UDF module. The flow characteristic of particles phase in the drying indoor is successfully simulated when the vibration frequency of vibrating fluidized bed is 0 Hz,10 Hz,15 Hz,20 Hz and the imported velocity of hot air is 0.5 m/s,1 m/s,1.5 m/s. Finally, the best operating parameters of VFBD were got. On this basis, the heat and mass transfer characteristics of ceramic particles vibrating fluidized bed drying are simulated when the storey bed is 75 mm,100 mm,125 mm and the imported temperature of hot air is 393 K,413 K,433 K,453 K. There are some results are be showed after simulation:1) When the amplitude A=3mm, vibration frequency f= 10 Hz and inlet air velocity va= 1 m/s, particles phase fluidized state is better, concentration of particles is uniform distribution, bed-storey is stable, and there is no large fluctuation or slugging and "air embolism" phenomenon in the whole drying process; 2) There are two periods in the drying process after the simulation analysis of heat and mass transfer characteristics of gas-solid, the two periods are constant rate drying period and falling rate drying period. And the bed layer height and inlet air temperature have a great impact on the drying rate; 3) In the 360s, the moisture content of ceramic particles in the bed is maintained at between 0.05?0.07 kg/kg, and it decreased slowly, the temperature of particles phase is higher, which is about 453K, the moisture content of ceramic materials meet the process requirements of tails.