Research On Electrostatic Precipitation Technology Of Unorganized Dust Emission Source

In some heavy industries such as electricity,steel and nonferrous metal smelting,and light industries such as textiles,flour,and timber,there will be a large amount of fugitive emissions of dust in the workshop.This part of the dust has the characteristics of low dust concentration,scattered dust source points,irregular discharge,and difficulty in capturing.Diffusion under the influence of hot-pressing and lateral air flow reduces the visibility of the workshop,severely pollutes the workshop's operating environment,accelerates the wear of electromechanical equipment,and affects the safe operation and physical health of workers.It also causes regional pollution.At present,domestic dust for fugitive emissions mainly uses large-capacity fans to pump flue gas from roof dust collection hoods or skylights and send it through pipes to a bag filter installed on the ground for purification.This method has good effect on the removal of dust,but it requires a large number of laying pipelines,high-power fans,running energy consumption,high cost.In 1972,Sumitomo Heavy Industries Co.,Ltd.took the lead in the development of a natural-ventilated vertical semi-wet electrostatic precipitator,which has been successful.China has also successfully applied rooftop electrostatic precipitators to the treatment of secondary flue gas such as blast furnace tapping,calcium carbide furnace,and submerged arc furnace.However,there are still many problems in the design and operation of rooftop electrostatic precipitators.In recent years,the application of rooftop electrostatic precipitators has been limited.In view of this,This research group proposed a vertical wet electrostatic precipitator(an industrial air purification system CN 107362648 A)in combination with a conventional flexible electro-electrostatic precipitator technology.The roof electrostatic precipitator device is placed on the roof of the plant and does not occupy the total map area.Only the diagonal fan with low power is installed at the exit of the precipitator,and the natural buoyancy of the flue gas hot press and the height of the electrostatic precipitator generate a strong pumping force,and the unorganized discharged dust particles are introduced into the roof electrostatic precipitator by the airflow organization.In this paper,according to different gray samples,the characteristics of the gray sample are studied.A small test bench is set up to study the removal characteristics of the different gray sample particles on the design test bench and further verified by pilot test to apply this technology to industry.On the one hand,the test needs to meet the removal standards for fugitive emission dust.On the other hand,it is necessary to complete the technical breakthrough of the roof electrostatic precipitator and solve the existing problems.First of all,according to the problems of the current roof electrostatic precipitator,combined with the traditional flexible electro-electrostatic precipitator technology,a vertical wet electrostatic precipitator is designed,a small test bench is set up,and the test analysis and analysis method is determined.The representative three kinds of ash samples(fly ash,pellet mill ash,and flour mill ash)were selected to analyze the composition and the composition and physical properties of the ash samples were analyzed to prepare for the study of the removal characteristics of different ash-like particles and the design of the grey water circulation system.Secondly,on the small-scale test bench,the removal characteristics of particulate matter from different gray samples were studied.The effects of working voltage,flue gas temperature,residence time and flushing water flow rate on the removal characteristics of particulate matter were investigated.The experiment found that:when the voltage is 50 kV,the removal efficiency of the total particulate matter in the flour mill is the highest,and the total removal efficiency of the pellet plant ash is the lowest,indicating that the roof electrostatic precipitator also has a good removal effect on the ash samples of organic components in the light industry.The prolongation of the residence time has significantly improved the removal efficiency of the three types of particulates,especially for fine particulates.The temperature and the change of the flow rate of the flushing water after the formation of the stable water film have little effect on the removal efficiency of the three kinds of ash-like particles.Through the study of the characteristics of gray water in different grey samples,the gray water separation method for filtration of fly ash and pellet mill ash was adopted.For the flour mill ash below 50 ?,the main use of filter membrane filtration of the gray water separation method,but pay attention to the design of automatic cleaning membrane filter device,to solve the problem of gray mills easy to block the filter hole.Finally,a pilot test was conducted at a 4×27000 VA silicomanganese ore furnace workshop at a metallurgical company in Ningxia,and the economics of this technology were analyzed.The stable operation of the electrostatic precipitator on the roof and the control effect of unorganized dust emission are obvious.After a third-party inspection,the smoke emission concentration in the exhaust outlet is less than 20 mg/m~3(operating condition),and the visual pollution around the workshop in the pouring project can be effectively eliminated.The grey water circulation system effectively saves water resources and realizes zero discharge of wastewater during operation.Compared with the traditional air-bag-type dust collection technology,the equipment investment cost for rooftop electrostatic precipitator technology is reduced by 40%to 60%,and the power consumption during equipment operation is reduced by 70%to 83%(per 1,000 Nm~3 of flue gas).