Numerical Simulation Of Gas Mixture In Titanium Dioxide Oxidation Process

The chlorination technology is an advanced technology to produce the high-grade titanium dioxide and the critical phase of it is oxidation process and the key process equipment of it is oxidation reactor. The mixture of gases in the oxidation reactor is closely related to the scar of the wall surface of reactor and the quality of the product. The high-temperature oxygen and preheat TiCl4(g) in the oxidation reactor should be rapid, uniform and close mixed in a very short period of time and a very small space. This paper study the gas mixing in reactor with numerical simulation, research the variation trend of flow field in the reactor with the trends of each factor, provide a reference for the actual production process to optimize the structure of the oxidation reactor.In this paper, the DesignModeler is used to build the 3D geometric model of oxidation reactor, which is a component of the software of finite element analysis, ANSYS. The gas mixture model is constructed to numerically simulate the mixing gases flows in the reactor with the basic equation of fluid mechanics and turbulence model with the FLUENT.According to the experimental results of the known literature data, two shares of room temperature air are used to simulate the preheat TiCl4(g) and high-temperature oxygen, the mixing situation of the two shares air is analyzed by numerical simulation with the same set of simulated conditions and experiment conditions, and the simulated results were compared with experiment results. The analysis shows that the variation of the concentration profile of the jet gas in the reactor is consistent with the variation of experiment, which verify the accuracy of the gas mixture model.The gas mixture model is used to simulated the mixing case of preheat TiCl4(g) and high-temperature oxygen in the oxidation reactor. By analysis the flow field shows that the uniformity of the gas mixture is better when the gas momentum ratio increases in the case of the structural of reactor is fixed, but the uniformity of gas mixture will be lower if the gas momentum ratio continue to increase when the momentum ratio achieve a constant value. When the opening area of the jet ring is fixed, the gas momentum ratio and the axial gas flow is constant, the number of opening holes of jet ring for gas mixing uniformity has a similar regularity with the gas momentum ratio, there is an optimum number of opening to achieve the best uniformly of gas mixing. TiCl4(g) in the oxidation reactor will form a reflux if the opening rate of jet ring blow a certain value when the number of opening holes is fixed, and the uniformly of gas mixing will be lower when the opening rate exceeds the certain value. The flow of oxygen has some influence on the gas mixing, the gas mixing will be better when the oxygen is a slight excess.Analysis of variance(ANOVA) of the results of numerical simulation of gas mixing affected by a combination of factors was conducted to analyze the impact of different factors on the uniformity of the gas mixture. The results showed that the number of openings and the opening rate of jet ring have a significant impact on the gas mixing, the gas momentum ratio and the flow of oxygen have no significant impact on the gas mixing.