Numerical Simulation Of Gas-Solid Flow Characteristics For Different Deducting Technology Using OpenFOAM

The deterioration of the environment has caused great harm to people's production and life with the rapid development of industry.In recent years,haze has become a hot word in the society,and its important component is fine dust.The dust particles suspended in the air are small in size and have strong adhesion,which seriously threatens people's health.Therefore,the control of dust particle emissions is a hot issue of people's livelihood.Industrial deducting is an important part of controlling industrial dust emissions.It is particularly critical for research of industrial dust deducting mechanism and gas-solid flow separation characteristics.At present,dust removal technologies for industrial dust separation and capture mainly include three types:Inertial separation,fiber filtration and electrostatic trapping.The gas-solid flow characteristics of two dust removal technologies will be simulated in this paper,including inertial separation?cyclone?and fiber filtration?the flat and pleated fiber filter media?.Dust removal mechanism and gas-solid flow characteristics are in-depth analyzed,and the results are of great significance to the development of industrial dust removal technology and the control of emissions.The numerical model of gas-solid two-phase flow was built using OpenFOAM?Open-source Field Operation and Manipulation?software,which used Euler-Lagrange method to describe the movement of gas-solid two-phase flow in this paper.First of all,the separation characteristics of cyclone dust separators about solid particles size of1-20?m were studied.In addition,in order to solve the existence of secondary flow,and the cyclone dust collector structure of common tangential inlets was optimized to improve the performance of cyclone dust collectors.Secondly,a microscopic three-dimensional model of a flat fiber filter medium and the microstructure of a pleated fiber filter medium were established using real fiber microscopic scanning electron microscope images,and the internal gas-solid two-phase flow process was simulated.The filtration characteristics of flat and pleated fiber filter media were analyzed under different operating conditions and structural conditions.At last,results of simulation were compared with the CFD-DEM?Discrete Element Method?coupling model and empirical formula calculation results.The simulation calculation costs of OpenFOAM gas-solid model and CFD-DEM coupled model were analyzed about the perspective of the consumption of computer resources and simulation time.Research indicates:?1?Using the Open FOAM gas-solid two-phase flow model,the results of the gas-solid two-phase flow simulation in the cyclone dust collector are in good agreement with the experimental data.The errors of pressure drop and efficiency are 9.89%and1.33%,respectively,so the simulation results are reliable.Introduction of secondary wind reduces the secondary flow of the cyclone dust collector,the formation of upper ash ring and short-circuit flow,and improves the separation efficiency of the cyclone dust collector.Introduction of secondary wind can increase the tangential velocity of the cyclone dust collector effectively and also cause a large pressure loss.When the secondary air inlet velocity is 15,25 and 30 m/s,the pressure drop of the cyclone dust collector is 2,3 and 4 times that of no secondary air pressure drop.The classification efficiency increases with the increase of wind speed of secondary air.When the inlet velocity of secondary air is 10 and 20 m/s,the classification efficiency increases obviously.When the wind speed is 30 m/s,the efficiency does not increase significantly.?2?The numerical simulation of gas-solid two-phase flow in flat fiber filter media could be realized well using Open FOAM.From the deposition morphology and particle distribution characteristics of solid particles,the dendritic structure formed of particles on the fiber surface by OpenFOAM simulated is very similar to experimental observations.The variation trend of pressure drop and efficiency of non-steady state fiber filter media under different particle size and St Number condition was analyzed,and both pressure drop and efficiency increased with the increase of deposition amount.This is due to the deposition of particulate matter filling the gap between the fibrous filter media,thus increasing the packing density of the fibrous filter media,resulting in the increasing of the pressure drop and filtration efficiency.?3?The process of deposition and formation of dendritic structures on the surface of the pleated fibrous filter media is well simulated using the OpenFOAM numerical model of gas-solid two-phase flow.Affected by the arrangement of fibers,the particles are deposited clearly in the area where the fiber meets the fiber with high densely packed.Therefore,the distribution of the number of particles deposited on the pleated fiber filter medium exhibits a bimodal form.With the increase of the pleat angle,the pressure drop of the pleated fiber filter media decreases first and then increases.At the gas velocity of 0.4 m/s and?=35°,?P_min=5.005 Pa.When the gas velocity of 1.2 m/s and?=60°,?P_max=18.124 Pa.The change of sedimentation quantity reflects the filtration characteristics of pleated fiber filter media under non-steady-state conditions.The pressure drop of pleated fiber filter media is gradually increasing with the increase of deposition amount,and the rate of increase is gradually increasing.With the increase of the amount of particulate deposition,the filtration efficiency of the pleated fiber filter media also increases,but the rate of increase is reduced.?4?Comparing OpenFOAM numerical simulation results with empirical formulas and CFD-DEM coupled model simulation results for fiber filter media,the overall trend has good consistency.The simulation results of the CFD-DEM coupling model are closer to the empirical formula,especially when the St number is larger,and the match between the OpenFOAM gas-solid model simulation result and the empirical formula is relatively poor.However,the CFD-DEM coupling model simulates the large computer resource consumption and long simulation time from the simulation cost analysis.The OpenFOAM gas-solid two-phase flow model simulation can simulate the deposition of particulate matter on the fiber surface and form the dendrite structure.The simulation results are closer to the experimental observations and the simulation calculation time is shorter than the CFD-DEM coupled model.Therefore,it is necessary to select the required model according to the actual situation.