Numerical simulation of heat transfer and chemical reaction of CaO-C porous pellets in the reaction layer of calcium carbide furnace

Abstract

In this paper, a three-dimensional multi-physical model is established to analyze the heat transfer and chemical reaction processes during the production of calcium carbide from CaO-C porous pellets. The model considers simultaneously radiant heat transfer, convective heat transfer, heat conduction and chemical reaction process in the pellet bed. The multi-physical fields are solved by finite element method, and the numerical modeling method is verified based on literature data. The results show that the temperature field and the reaction region are strongly coupled and inhomogeneous in the reaction layer. The reaction diffuses from the surface of the pellet to the inside, and the center of the reaction region gradually shifts to the low temperature side. In the case of three-layer pellets, when heat is transferred from one layer to the upper layer, the time required is about 80% of the total reaction time of the current layer. In addition, the orthogonal test was carried out in the present study, and the result shows that the radius of the particles, velocity of the gas and the surface emissivity of the pellets have influence on the reaction process, and the degree of influence gradually decreases. When these three parameters changed from 1 mm to 0.71 mm, 0.01 m/s to 0.1 m/s and 0.7 to 0.9, the output of calcium carbide increased by 8.74%, 3.52% and 1.3% respectively in the same reaction time.