Study On Structure Optimization Design Of Electrostatic-fabric Integrated Precipitator

In recent years,in order to reduce air pollution and improve air quality,the state has issued relevant policies and regulations,striving to implement energy conservation and emission reduction strategy,the electrostatic-fabric integrated precipitator has been widely used.It is a kind of composite precipitator which combines electrostatic precipitator and bag filter.It has high efficiency of dust removal and good effect of PM2.5 capture.It is effective to develop and study the electrostatic-fabric integrated precipitator to reduce the air pollution of coal-fired power plant.Whether the flow field in the electrostatic-fabric integrated precipitator is uniform or not will have a great impact on its system resistance and the service life of the filter bag.The advantages of the numerical simulation method include convenience,economy,accuracy,etc.In this paper,taking a power plant’s electrostatic-fabric integrated precipitator as the research object,first using CFD numerical simulation method,through the optimization of the internal structure arrangement mode and design parameters of the electrostatic-fabric integrated precipitator,to achieve the reasonable distribution of air flow in the precipitator.Ensuring the flow distribution of each branch pipe and each bag area is uniform,and the air flow into the electric field area and bag area of the electrostatic-fabric integrated precipitator is evenly distributed,so as to achieve the high efficiency and stability of the electrostatic-fabric integrated precipitator,the outlet particle concentration meets the emission index.Firstly,the influence of the height of the lifting valve,the diameter of the lifting valve,the baffle plate and the permeability of the filter material on the air distribution is studied under two different positions of the outlet flue(the outlet flue is at the side of the bag chamber and the outlet flue is at the middle of the bag chamber).The results show that the height of the lifting valve and the permeability coefficient of the electrostatic-fabric integrated precipitator are the main factors affecting the performance of the electrostatic-fabric integrated precipitator,and when the outlet flue is arranged in the bag chamber on the side,the best balance of airflow distribution and resistance can be achieved.By setting a reasonable air distribution device in the inlet flue and the inlet horn,the relative flow deviation of each channel of the electric bag composite precipitator can be less than±5%,the relative root mean square value of the velocity field distribution in the section of the electric field can be less than 0.15,and the distribution of the overall flue gas flow field including the inlet and outlet flue is relatively uniform.Then,a physical model test platform of air flow distribution of the electrostatic-fabric integrated precipitator is established,and the flue flow distribution test,the bag compartment flow distribution test and the air flow distribution test at the entrance of the electric field area are carried out respectively.When the air flow distribution device of the inlet flue is set up according to the design scheme,the relative flow deviation of the left,middle and right chambers is-0.438%,-0.868%,+1.306%,which meets the research objective of less than±5%.It is required to arrange 145 mm high baffles between the electric field and the front bag,and 70 mm high baffles between the front and the back bag,the lifting height of the lifting valve in the front bag area is 90 mm,the lifting valve in the back bag area is 60 mm,and the relative flow deviation of each compartment in the bag area is±4.65%,which meets the research objective of less than±5%.When the air distribution device of the inlet horn is set according to the design scheme,the relative root mean square differences at the entrance of the electric field areas of the left,middle and right chambers are 0.146,0.148 and 0.147,which meets the research objective of less than 0.15.Finally,the electrostatic-fabric integrated precipitator optimized by numerical simulation and physical model test is applied to the project,and the performance test of the electrostatic-fabric integrated precipitator is carried out.The results show that the measured air leakage rate of each chamber is less than 1.8%,the resistance of each chamber is less than600 Pa,the flue gas flow deviation of each chamber is less than 5%,the flue gas concentration at the outlet of each chamber is less than 5 mg/m~3,and the dust removal efficiency of each chamber is high at 99.985%,all performance indexes meet the requirements of design parameters.