CFD Flow Simulation Of Disproportionation Furnace

Disproportionation furnace is an important heating equipment for the toluene disproportionation process,and the safe and stable operation of the equipment is important.A domestic refinery disproportionation furnace encounter two problems during the operation: one is that there is a lot of noise at the flue,and the other is that the flue gas can communicate among radiation chambers since radiation chambers share the same convection chamber in this integrated furnace.To provide theoretical guidance for solving these problems,the present work numerically studied the disproportionation furnace with CFD methods by analyzing the detailed flow behaviors of the flue gas in the chamber.The cause of noise at the flue was found and the effect of furnace integration was discussed.Based on the obtained information,the optimization measures of structure and operation conditions which influence the gas flow in the furnace were researched,which provides guidance and reference for the better design of the disproportionation furnace.First,based on the comprehensive mathematical model for the furnace and the industrial data,the flow behaviors of the flue gas in the disproportionation furnace were simulated.The results showed that the reason of the noise was the high flow rate of gas and the large flow resistance in the flue of F101 furnace,which is related to F101 furnace? geometry structure.Moreover,the serious bias flow of the flue gas occurring at the exit of F101 and F102?flue affected the heat transfer in the convection chamber greatly.The results also showed that the integration of furnaces led to the phenomenon of gas communication among radiation chambers,and it was needed to improve its performance by optimizing the operating conditions.Then,in order to optimize the overall geometry structure,the present work increased the height of F101 radiation chamber to the same height of other chambers.The simulation results showed that the gas communication phenomenon among radiation chambers was slightly improved.However nothing has been changed for the problem of the flue.Then the impacts of local geometry structure,including the firewall height,the inclination angle of flue and the ratio of height to diameter of flue,on the disproportionation furnace gas flow were investigated.The results showed that when the firewall height was 8.0m,the gas flow field above the combustor was more uniform.Besides,when the inclination angle of flue was 53° and the ratio of height to diameter was 0.93,the flow problem of the flue could be well solved.Finally,for the operation difficulty due to the integration of furnaces,the present work investigated the impacts of excess air coefficient,operation load and burners working status on the mutual interference process of the flue gas flow among burners and on the phenomenon of gas communication among radiation chambers.The results showed that when the excess air coefficient was 1.10 and the operation load was 110%,the problem of gas communication among radiation chambers could be well solved.And when a row of burners in the middle of the F103 furnace was stopped to work,the problem of gas communication among radiation chambers and the serious bias flow occurring at the exit of F101 and F102?flue could be well solved at the same time.