Research On Separation Characteristics Of Monitoring Instruments Of Fine Particulate Matter Concentration For Stationary Sources

In the past decade,severe haze weather has taken place in many parts of our country and has had a huge adverse impact on all aspects of social production and life.Haze is mainly formed by the condensation of some solid fine particulate matter in the atmosphere,most of which comes from the emission of stationary source dust from power plants and factories.Whether the fine particle concentration emitted from stationary source can be accurately monitored is the key of the prevention and control of air pollution.In our country,the study on the monitoring system on stationary source flue gas particulate concentration is relatively late,and the related research is not yet mature.In this paper,a monitoring system on stationary source flue gas particulate which is based on atmospheric environment and consisting of EPAMethod 5,charged low pressure impactor,diluter and other instruments is seen as the research object,the monitoring system can separate the particulate matter in the soot over and over time and measure the particle concentration range from particle size.In this paper,the separation performance factors of the segregators which have two different functions including cyclone separation and impact separation were analyzed.In the EPA-Method 5,10 PM cyclone separator separates particles whose particle size greater than critical particle size.According to the design criterion of the cyclone separator,the structure size of the particle was designed and the three-dimensional physical model of the flow field was established.And then the numerical research on gas-solid two-phase flow was carried out in the process of internal separation.Firstly,RSM turbulence model was used to simulate the gas phase,and the velocity distribution of the gas phase was analyzed to get the effect of the flow field in the form of internal and external vortices on the particle motion.The particle separation was obtained by adding particles to the gas-solid coupling calculation with discrete phase model.And then based on the initial project,the exhaust pipe length and diameter parameters were changed over and over times for comparison to meet the separation performance requirements.The results show that when the exhaust pipe length and diameter are reasonable,the short-circuit flow can be effectively suppressed,and the external vortex region is enlarged,besides,the separation performance is improved.After pre-separation and dilution,the flue gas entered the ELPI to determine the particle concentration.This article simplifies analysis of ELPI,and then according to the design criteria of the impactor separator,the structure of the 2.5 1PM-PM two-stage impact separator was designed as well as the three-dimensional physical model of the flow field was established.Adapt to low-Reynolds numbers turbulence model(k-? model)and the discrete phase model were used to simulate the gas-solid twophase flow in the separation process.Through a large number of the simulation analysis which changes the air flow parameters,structural parameters and other operating parameters,it can be learned that when the Stokes number is reasonable,the double decking arrangement of nozzle reduces the lateral flow resistance of the gas flow.The decrease of the nozzle diameter or the collision distance within a reasonable range will improve the separation performance.When the theoretical value is exceeded,the separation performance will be affected by the eddy.The research results of this paper can provide some references for the particle separation principle of the monitoring system on stationary source flue gas particulate concentration and further exploration of the measurement on the smaller particle concentration.