Numerical Simulation Of The Calciner With Coal’s Combustion And Decomposition Of Calcium Carbonate

Calciner is the main reaction vessel of the system of precalcination in the dry-process cement’s production line, where the decomposition of raw materials and the combustion of coal take place. It has several important practical applications, such as reducing the heat load in the rotary kiln, increasing the rotary kiln’s capacity and reducing pollutant emissions in the cement production process. With the development of Computational Fluid Dynamics(CFD), more and more people attach the importance of numerical simulation method, which can save much time and cost. Numerical simulation has become an effective means in the calciner’s research.Based on FLUENT6.3, the main work done by the author are listed below:By modeling the calciner, select suitable structure and quantity of the grid. Frist,3-D gas turbulence flow in the calciner was simulated. Seek appropriate calculation methods, turbulence model, boundary conditions, etc. Then analyze gas phase turbulence flow pattern. Based on the3-D gas phase turbulence flow simulation, the gas-solid two-phase turbulence flows was simulated by Discrete Phase Model (DPM). Then simulate the3-D turbulence flows with pulverized coal’s combustion. In the end, simulate the gas-solid turbulence flows with pulverized coal’s combustion and raw materials’decomposition. Finite-Rate/Eddy-Dissipation model was adopted in the simulation of pulverized coal’s combustion and raw materials decomposition.The results of this thesis are listed below:The gas turbulence flow was simulated by Realizable κ-ε model and SIMPLE method. The distribution of pressure and velocity showed that the flow field in the calciner are basically jets and uneven. The results conform to the movement trend in the calciner. The gas-solid turbulence flow was simulated by DPM model. We could figure out the velocity in the calciner, the trajectory of raw materials and pulverized coal. Pulverized coal and raw materials rise up in the form of jets after they are sprayed into the calciner. Then they are diffused and mixed. A fraction of them is in a way of rotation flow, which can extend the residence time of the materials. Based on the predecessors’work, the pulverized coal’s combustion and decomposition of calcium-carbonate were simulated by Finite-Rate/Eddy-Dissipation model. And then, the distributions of the temperature, velocity, pressure and volume fractions were obtained. The results showed that the flows of the pulverized coal’s combustion and decomposition of calcium-carbonate are in line with the actual situations.