| The air pollution of China is typical coal combustion pollution. The main pollutions are inhalable particles and SO2. The limestone-gypsum WFGD(Wet Flue Gas Desulfurization) spray scrubber became the main style of desulfurization tool, but there isn’t a well proved and accepted model of the three dimension model of SO2 absorption process of WFGD in academia. The inhalable particles and desulfurization wastewater pollution became the causes for concern because of the widely used of WFGD and the pollution of haze.The flow and SO2 absorption process in WFGD spray scrubber were studied by CFD based on the modified SO2 absorption model. The inhalable particles movement characteristic inside the high humidity spray scrubber was studied in which the effect of vapor was included. The WFGD wastewater zero discharge proposals feasibility was systematic studied and a field test was carried out for the first time in domestic. The main conclusions are shown as below.1) The modified SO2 absorption model of droplets in WFGD spray scrubber was derived from the analysis of the SO2 absorption mechanism. The two phase flow, heat and mass transfer model in WFGD spray scrubber was established by the combination of Euler-Lagrange model and the modified SO2 absorption model, in which the modified SO2 absorption model was complied as UDF(User Defined Function). The comparison between simulation results and reference results showed a good agreement. The effect mechanism of main parameters to the flow and De SO2(Desulfurization ratio) was studied by this model for the first time, the formulation of De SO2 and L/G(Liquid Volume and Gas Volume ratio) was obtained by the fit with the simulation results. The affluence microscopic mechanism of high desulfurization ratio system was studied based on the formulation, which could give theory fundamental and method to the affluence design of WFGD system.2) The inhalable particles steam condensation model in supersaturated vapor environment of WFGD was put forward for the first time, and then the movement and evolution mechanism model of inhalable particles in WFGD was established based on the inhalable particles steam condensation model and Euler-Lagrange model. The simulation results showed that the inhalable particles removal ratio increase as the increase of L/G.3) The gas droplet two phase flow in the desulfurization wastewater zero discharge device was simulated by the Euler-Lagrange two phase model and droplet evaporation model. The effect of duct structure, gas temperature, droplet diameter and location of the nozzle was studied, and then the feasible technical proposal was obtained. The device was designed and optimized based on the technical proposal, and then the field test was conducted. The effect of this device to WFGD and ESP(electrostatic precipitator) was studied by the comparison analysis of the running parameters before and after the running of the system. The test results showed the device had no bad effect to the running of WFGD and ESP, and desulfurization wastewater zero discharge was achieved.4) The granules movement, evolution and deposition model inside the duct were established, in which the Euler-Euler two phase model, PBM(Population Balance Model) and particle deposition model were included. The granules movement, evolution and deposition in the desulfurization wastewater zero discharge device was simulated, the effect between agglomeration and deposition of granules was studied. The results showed the diameter of the particle increased because of agglomeration, the main deposition mechanism was gravity, and the deposition phenomenon appeared as the increase of the spraying load increase. |
