Numerical Simulation Of Flow Field In The SCX Scrubber For Wet Dedusting And Desulfurizing

In this paper, the author summarizes the current condition and feature of the air pollution in China, and introduces the harm of the air contamination briefly, and introduces the process of the flue gas desulphurization used in the industry around the world and the technique of dedusting and desulphurization simultaneously in brief. The SCX scrubber is a kind of the facility which dedusts and desulphurizes flue gas simultaneously, it has the capacity of dedusting and desulphurization synchronously, containing the advantages of the cyclone device and wet scrubber, it is the production of Hunan university. The theory of CFD and its applications in the environment region is explained, the relationship of the softwares in the FLUENT package is introduced as well, in addition the feature of Gambit and FLUENT is mainly introduced.The SCX dedusing and desulphurization scrubber was researched using FLUENT, a kind of computional fluid dynamics software. In order to research the fluid feature of the flue gas in the facilities with different inner device, selecting the flue gas as the continuous phase, computing the N-S equation, and choosing the k-e series turbulence equation to enclose the solving equations. The numerical simulation shows that the deflectors in the bottom of inner pipe has serious influences to the pressure drop of the whole facility, optimizing its struction could be decrease the pressure drop of whole facility effectively.On the base of simulating one phase, realizable k-εturbulence model, Discrete Phase Model(DPM) were used in the simulation of three-dimensional gas-solid flow in the SCX dedusting and desulphurization scrubber by using FLUENT package. The SIMPLE which is one type of pressure-velocity coupling algorithm was used in the calculation. The distributions of gas pressure and velocity at cross-section of z=0 in the scrubber were analyzed deeply; the concentration distribution of different size particles and the particle trajectories were computed as well. The concentration distribution of particles with and without the influence of gravity was also researched. The simulation results show that there is the maximum pressure drop on the gas deflector, over 1000 Pascal. In inner-pipe, the vortex of gas is weak, and some backflows phenomenon is observed in the cone shell. The gravity barely influences the distribution of the fly-ash and the particle concentration in the lower part of cone shell in which there is the highest concentration is up to 0.01 kg/m3. Using the Discrete Phase Model(DPM) create the droplet injecting source, and choosing the droplet as discrete phase, flue gas as continuous phase, computed the gas-liquid multiphase couplely Depicting the trajectories of droplet in Lagrange coordinate. The simulation results show that droplets from the nozzles blocking the movement of the flue gas, decline the velocity of the gas in the inner-pipe, but the velocity distribution does not change. The improved rotating deflector eliminator is important for the facility to run normally, when there is not the improved eliminator, the number of droplets in outlet of the facility increase sharply. The simulation results introduced above are of major significance and practical operation, and providing evidence for the optimization design further more.