Numerical Simulation Study Of Drying Process In Rotary Drum Dryer

For developing countries, the low quality coal plays an important role in the process of energy providing. Lignite is one of the coals which have the lowest degree of coalification and most lignite is buried in the shallow layer. It is economically and accounted about 23 percent of the total coal reserve. Almost all of the lignite can be open, so that the price is low. Lignite has high water content, which leads to the low calorific value. It is not suitable for long distance transportation, and severely limiting its further utilization. The purpose of the thesis is to develop efficient lignite drying technology and equipment, so that we can dry lignite more efficient.In this paper, we see the rotary drum dryer as the research object. Using Fluent to simulate the rotary cylinder dryer and observe the pattern of the internal flow field.First, introducing the methods of the rotary drum dryer geometry modeling, mesh and set of boundary conditions. Then respectively from the numerical simulation of the gas phase and gas-solid two phase flow.Single gas phase simulated includes original structure simulation, the speed field which have increased turbulence device, stress field numerical simulation. Including the setting of computing model and solving method, and analyzing the simulation results. The results of gas phase simulation can provide reference for the analysis of the gas-solid two phases.The numerical simulation of gas-solid two-phase flow include original structure simulation and increase the turbulence device after the new structure of velocity field, temperature field and pressure field numerical simulation. This process is so complex that we use the turbulence model, multiphase flow model, component transport model and custom UDF evaporation model. Through analyzing the simulation results, we can get the flow field velocity and pressure temperature distribution, and comparing the two structures. We can find that the results are consistent with the actual situation.Using discrete phase model simulate the gas-solid two-phase flow, We can come to the conclusion that the smaller the particle diameter, affected by the flue gas is relatively obvious, the bigger the particle diameter, less affected by the hot air and greatly influenced by copy board. These results provide a theoretical basis for late dryer structure improvement and optimization of the structure.