| Wet dedusting technology is widely used in modern industrial production,and has become an important means to effectively remove industrial dust.However,the traditional wet dedusters still have difficulty to remove fine particles(such as PM2.5)with high efficiency.The flow around baffles was found to induce vortex flow for enhancing industrial dust removal process.In this paper,a new wet dedusting system with baffle structure is designed and developed based on the combination of wet dedusting and baffle flow technology.The complex multiphase flow in the dust collection area of this system is analyzed by means of numerical simulation and experimental study,aiming at the characteristics of gas flow field,the parameters of vortex structure,the movement of spray droplets and solid particles around baffles.What’s more,some improvements are proposed according to the simulation results.The main research work are as follows:The accuracy of different turbulence models in the prediction of baffle flow is compared and analyzed.Four common turbulence models,Standard k-ε,RNG k-ε,SST k-ωand RSM models,are selected to simulate the two-dimensional baffle flow in dust collection area.Compared with the experimental results,RNG k-εmodel can accurately predict the main features of vortex flow and its internal longitudinal velocity distribution.Considering that the longitudinal velocity dominates the gas-phase flow in the dust collection area,RNG k-εmodel is selected as the turbulence model for the numerical simulation in this paper.Based on the commercial finite element analysis software ANSYS-Fluent,a new multiphase flow simulation platform for wet dedusting system with baffle structure is constructed.The characteristics of the gas flow field in the dust collection area,such as the vortex structure,velocity distribution,pressure distribution and the action range of the vortex,are simulated.The influence of baffle placement angle and inlet velocity on the gas phase field is analyzed.It is found that the arc baffle can reduce the"dead zone"area of low-speed gas phase in varying degrees and the functional relationship between the efficiency of vortex interaction and the baffle placement angle and Reynolds number is obtained.Discrete phase model（DPM）is used to study the trajectory,escape rate and residence time of spray droplets under different working conditions.The dispersion and stress of solid particles in the dust collection area are analyzed by computational fluid dynamics（CFD）coupled discrete element method（DEM）.It is found that the existence of vortex flow can improve the escape phenomenon of spray droplets and effectively prolong their residence time in the dust collection area.Considering the effects of gas inlet velocity,baffle placement angle and droplet size,the model formula for predicting droplet escape rate is derived.Under the action of vortex,the solid particles form obvious recirculation flow in the downstream area of the baffle.The numerical simulation results show that the interaction between the solid particles and the vertical wall is the main form of collision,and the impact normal stress analysis shows that the wear effect of the solid particles on the upper baffle is much greater than that on the lower baffle.When the placement angle is 90 degrees,the dispersion uniformity of solid particles in the baffle area is better.Smaller particles tend to enter the vortex due to the centrifugal force.The experimental platform of wet dust removal system is set up.Based on laser induced fluorescence（LIF）and particle image velocity（PIV）technology,the actual flow of gas phase in the dust collection area is measured visually.The experimental results of vortex structure and velocity field are in good agreement with the numerical simulation results,which verified the reliability of the numerical method.In order to further improve the performance of the system,based on the numerical simulation results,some improvement schemes are proposed,such as periodically increasing the number of baffles,adding vertical baffles and adjusting the position of nozzles.The numerical simulation results of the improved model show that the key performance parameters such as spray droplet escape performance,solid particle dispersion uniformity and"flow dead zone"suppression are effectively improved.It provides certain reference and guiding significance for the development of industrial wet dedusting technology. |
