The Numerical Simulation Of Gas--Solid Flow In Chamber Of Four Wall Tangentially Fired

The research on the pulverized coal flow and combustion in the pulverized coal furnaces is one of the most significant studies of the control of pollution resulting from the coal combustion. Due to the complicated heat exchange in the chamber, it is difficult to deal with the research in the laboratory solely. With the progress of the computer technology, people are beginning to apply the approach that includes the test in laboratory and the numerical simulation to study the process of the flow, the heat transfer and combustion in the chamber. Though some people study the pulverized coal furnaces with numerical simulation method, there is some mechanism problem and the numerical simulation methods to be resolved and make perfect. Therefore, the main text of this paper is, firstly to construct a reasonable mathematics model for the combustion, And then to analyze the turbulence flow velocity field, the temperature field and the density field with numerical simulation method, lastly to compare the test data and to prove the rationality of the model.This paper is to take the test model of a 1MW pulverized coal furnaces of four wall-tangentially-fired as the research subject. According to the structure characteristic of the chamber and the flow characteristic, the author uses two approaches: one is an approach of rotating the mesh system to divide the area of burning; the other is an approach of the block-structured grid method and the adaptive grid technology to divide the mesh and refine the grid. This method can reduce false diffusion in the numerical simulation, ease the difficulty of the mesh generation, and control the numbers of the mesh, which can save the computing time efficiently.As to the gas phase flow field, author chooses the standard k - model, the realizable k - model and the Reynolds stress model to make simulation and comparison. In the same case of the initial conditions and boundary conditions the expectation result of the realizable k - model and the Reynolds stress model is better to the standard k - model, and moreover the expectation result of the Reynolds stress model is close to the test result. The realizable k - model is more reasonable in the chamber simulation on the common condition for its little computation amount. In addition, thepaper uses first-order upwind scheme and second-order upwind scheme and QUICK scheme to compute convection. Through comparison and analysis, the paper chooses second-order upwind scheme as discrete scheme of convection.This paper adopts the Particle-Trace model to simulate the track of particle. This model can reduce the computer memory and save time, simulate the complex process of the particle phase and use Lagrange method to reduce the false diffusion. The Random Particle-Trace model Simulate the turbulence diffusion. This paper compares the computing results of the one-way coupling method and two-way coupling method, and the result indicates that the one-way coupling method is applicable when the mass and momentum ratio of the discrete phase in the turbulence flow velocity field is small in the chamber.