| PM2.5 is one of the causes of the haze problem.However,the capture rate of PM2.5 in the flue gas by the existing technology and equipment is extremely low.In addition,China has tightened its pollutant emission limits.Therefore,there is a great need for fine dust removal technology for PM2.5.Our research group has creatively designed a system that uses electromagnetic fields to drive magnetic porous media to capture fine dust in flue gas.In this paper,the method of numerical simulation is used to further optimize the system.This research is based on existing materials and equipment.First,the self-made magnetic porous material is improved.Theoretical analysis and calculation of dust collection efficiency are made using the trapping mechanism,and mathematical and physical models are established using theories of gas-solid two-phase flow and electromagnetics.In order to making up for the unknown influence caused by the pore structure of porous media in the theoretical calculation,the fractal theory is used to simulate the trapping efficiency of a single multi-medium,and the fluent software is used to clarify the influence of the diameter,porosity and relative velocity of porous media on the trapping efficiency.Then,the trajectories of the two magnetic porous media in the combined magnetic field were numerically simulated.The UDF was compiled and added to apply the magnetizing force to find the law of the magnetic induction intensity required for different magnetic media.The feasibility of mixing two kinds of porous media into the same magnetic field was proved.Finally,the experimental results in the literature are compared with the results of numerical calculations to verify the accuracy of the simulation.Theoretically,the efficiency of PM2.5 capture by porous media is calculated.It can be seen that the smaller the diameter ratio of dust to magnetic porous media is,the better the dust capture is.The results of using fractal theory to simulate dust collection in a single porous medium show that the velocity distribution inside a single porous medium is non-uniform,and the pore density affects the seepage characteristics of the porous medium.The porosity of the porous medium should not be too large or too small.The capture efficiency is highest when the porosity is 70.23%.The relative speed is directly proportional to the capture efficiency,and the particle size of the porous medium is inversely proportional to the capture efficiency.The capture efficiency is highest when the particle size is 25 μm,and the simulation results agree with the experimental results in the literature..The trajectory of the magnetic porous medium under the combined magnetic field is simulated and analyzed.The results show that the addition of the combined magnetic field is beneficial to the long stroke movement and recovery of the porous medium.The steel wool with a particle size of 25 μm has the highest filling rate and low power consumption and material costs.When steel wool is used to replace porous nickel,the coincidence rate of the porous medium and the dust trajectory is basically the same,which proves the feasibility of mixing the two porous media into the same magnetic field for movement.At this time,the particle diameter of the steel wool should be smaller than that of porous nickel.Finally,by comparing with the experimental results in the literature,it can be seen that the trend of the magnetic trajectory is basically the same,which verifies the correctness of the model. |
