Numerical Simulations And Mechanism Experiments On The Dust Removing Characteristics Of An Electrostatic-Fabric Integrated Precipitator

Fine particulate matter is the most complex pollutant in the atmospheric environment, which has become one of the main risks affecting the environmental quality and human health. 70% of the electricity in China comes from coal-fired boiler, and the particulate pollutants generated from the coal-fired boiler is the main source of particulate matter in the atmosphere. According to national standard GB13223-2011, Air pollutant emission standards for thermal power plant, the emission of coal-fired boiler of key areas is not allowed to exceed 20 mg/m3, and the coastal areas of Guangdong are even developing the pilot of 5 mg/m3 ultra clean emission. The continuous improvement of environmental standards has brought great challenges to the dust removal equipments of coal-fired power plant. The electric-bag integrated dust removal technology combines the advantages of electrostatic precipitator and bag filter, which can not only ensure the strong trapping ability for fine particles with high dust removal efficiency of more than 99.9%, but has the advantages of a small filter pressure drop and durable filter bags. This kind of precipitators has proved extremely effective and helpful once put into use.In this paper, the dust removal characteristics of electric-bag integrated precipitator(EFIP) were studied from the aspects of laboratory experiments, numerical simulations and on-site tests.In the aspect of laboratory experiments, the particle removal mechanism of fine particles was studied by using the self-developed test platform of EFIP. The effects of different factors on the dust removal efficiency and PM2.5 removal efficiency were investigated by changing the flue temperature, moisture content and working voltage.In the aspect of numerical simulations, a 1000 MW EFIP were modelled by using PRO/E. The comparison of simulating results under some actual working conditions by using FLUENT, one of the CFD softwares, to the experimental data provided by a power plant vadiated the reliability and accuracy of the simulation results. Then the effects of the operating conditions and particle characteristics on the dust removal efficiency of the precipitator were simulated and the results were analyzed. At last, the removal characteristics of the fine particulate matter were studied by doing some particle tests in a power plant.The main results were as follows:(1) The dust removal efficiency of EFIP can be improved by decresing the temperature of flue gas, increasing the moisture content, decreasing the inlet velocity and increasing the internal resistance of the precipitator.(2) Acording to the electric dust removal mechanism, when the particle size and particle charge increase, the dust removal efficiency increases; for the collection of particels with high specific resistance, with the decrease of the temperature, the specific resistance is reduced, thus improving the dust removal efficiency.(3) Extending the cleaning cycle to 1.75 times of that, the increase of internal resistance of the precipitator can help increase the removal efficiency of fine particulate matter.The results of this study can provide theoretical guidance for the actual operation of the large electrostatic-fabric integrated precipitator.