Design, Experiment And Simulation Study On A Composite Wet Dust Collector

In the dust removal applications, for the dust laden air with harmful gases or combustible dusts, wet dust collectors has more advantages than dry dust collectors. Compared with dry dust collectors such as bag filters, single mechanism wet dust collectors hane the problem that flow rate is small and dust removing efficiency is low. Development and study of composite wet dust collector are meaningful for dust removal in applications with harmful gases and combustible dusts.A composite wet dust collector combined by water-bath and porous-media-spray with air flow rate200～500m3/h and diameter0.5m was built, The influences of operation parameters on the dust removal performance was investigated. The dust removal performance of the composite wet dust collector and the2single-mechanism wet dust collectors were compared. The flow field in the key area of the water-bath dust collector was simulated. The study methods and results are practically valuable for development of composite wet dust collectors with high efficiency.At condition that entrance dust concentration c is1.69g/m3, the effects of air flow rate, spray water flow rate, height of water level in the bath tank, height of porous media and type of porous media on pressure drop and the dust removal efficiency. The main conclusions are as follows:(1) While the spray water flow rate increases, pressure drop and the dust removal efficiency of the wet dut collector increase. At condition that spray water flow rate reaches2.02m3/h, the pressure drop P is610Pa, the dust removal efficiency η is99.42%. While the height of water level in the bath tank increases, pressure drop and the dust removal efficiency of the wet dut collector increase. At condition that the height of water level in the bath tank reaches0.310m, the pressure drop P is700Pa, dust removal efficiency q is99.90%. For both ladder ring and hollow ball, whlie the height of porous media increases, pressure drop and the dust removal efficiency of the wet dut collector increase. However, pressure drop and the dust removal efficiency of hollow ball are higher than which of ladder ring. At condition that the height of both of the porous media reach0.300m, to hollow ball, the pressure drop P is635Pa, the dust removal efficiency η is99.77%, pressure drop per unit height of the hollow ball is160Pa/m; to ladder ring, the pressure drop P is610Pa, dust removal efficiency η is99.46%, pressure drop per unit height of the ladder ring pressure drop is153Pa/m.(2) The performance of the composite wet dust collector, the single water-bath dust collector and the single spray-porous media dust collector were investigated. As the air flow rate increases, pressure drop and the dust removal efficiency of3kinds of wet dust collectoers increase. But the pressure drop and the dust removal efficiency of the composite wet dust collector are higher than which of both of the single wet dust collectors. When air flow rate is395m3/h, pressure drop of the3kinds of wet dust collectors are P1=1300Pa, P2=1150Pa and P3=530Pa, respectively. The dust removal efficiencies of the3kinds of wet dust collectors respectively are η1=99.71%,η2=98.00%and η3=96.48%.The flow fields and velocity magnitudes were simulated at6different entrance flow velocities in the range of4-26m/s. Simulation results are as follows:At the entrance of the wet dust collector, due to the flow direction has changed and flow area has increased, so vortexes have been produced. The number and size of vortexes increase with the increasing of air flow velocicy. At condition that air flow velocity is more than22m/s, the number and size of vortexes have increased. At the same time, impact that dust laden air to liquid level also increases with the increasing of air flow velocicy. Existence of vortexes has lengthened residence time of the gas and has increased contact time of gas、 liquid and solid. So it is helpful to strengthen mixing among all phases, which can increase dust removal efficiency; while increasing the impact on the liquid level is helpful to strengthen the dust drop, which can also increase dust removal efficiency. Through the simulation, the paper shows for both composite wet dust collector and water-bath dust collector, while the air flow rate increases, the dust removal efficiency of the wet dut collector increase.