Numerical Simulation And Optimization Study In The New Types Of Towers With Umbrella Sloping Plates For Wet Dedusting And Desulfurizing

This dissertation first introduces status on the air pollution in China. The total suspended particulate(TSP) and sulfur dioxide are still the primary air pollutant of China in present period,and environment protection operators have done a lot of study to reduce and control the air pollutant. Some industrialized technologies of flue gas dedusting and desulfurization are reviewed and analyzed,and the principles and characteristic of the technologies of dust-collecting and desulfurizing.On the basis of systematically summarizing predecessors' work,Professor Li Caiting designed the new towers for wet dedusting and desulfurization, which were the tower with umbrella sloping plates. With the high efficiency of dust removing,simple and compact configuration ,and low operating cost,the equipments has wide application in the future.In the paper,the gas- solid two-phase flow and gas-liquid two-phase flow in the new type of tower was numerically simulated by using of CFD (computational fluid dynamics) software.Theκ?εturbulence model,Eulerian Model and Discrete Phase Model(DPM) were used to simulate the 3-D gas- solid two-phase flow in the new types of wet dedusting and desulphurization tower with umbrella type plates by using FLUENT package , SIMPLEC algorithm was used in simulation. The distributins of the gas-solid volume fractions and fly-ash concentration,velocity and pressure were analyzed. Simulation results show that:the umbrella type plates can make gas distribute more even in the tower and delay residence time,so that the dust gas can be purified with high efficiency. When fly-ash concentration was very low,DPM would suit the gas-solid simulation better.The RNG turbulence model and Discrete Phase Model (DPM) were used to simulate the 3-D two-phase flow in the new WFGD with umbrella plates by using Fluent6.2 package and SIMPLE algorithm calculation method. Velocity field , pressure field and distributions of liquid drops in demisters with serrated baffles and rotated-stream trays in the tower were analyzed. The results showed that the pressure declined obviously when flue gas flowed through the demister with serrated baffles, where turbulent dissipative was very intense at corner regional, which would be beneficial to separation of gas and liquid. Both the gas velocity profiles and total pressure distributions were well axial symmetric when flue gas passed by the demisters with rotated-stream trays, which the liquid drops were revolved and threw toward wall surface by flue gas to carry out gas-liquid separation.Finally,the simulation results are of major significance for the optimization design and practical operation of the tower. Using CFD simulation method can shorten device developed time and reduce experiment and design cost, which possesses a very good economic benefit.