| With the rapid economic development,the iron and steel industry,as the "pillar" industry of China’s national economy,produces a lot of pollutants in the production process.At present,a large amount of high humidity dust will be produced in the mining project of iron and steel complex located in the humid southern region.If the bag filter is used for treatment,condensation and bag paste will easily occur,which will lead to the failure of the dust collector.Microporous membrane dust collector can well avoid bag sticking due to the application of PTFE microporous membrane filter,as the PTFE microporous membrane filter is of high hydrophobicity.However,most of the conventional microporous membrane dust collectors use mechanical rapping method to clean the dust,which has the disadvantages of low efficiency and short service life.Therefore,it is entirely feasible to combine the microporous membrane dust collector with the rotary pulse-jet dust-cleaning technology to design a new type of rotary pulse-jet dust-cleaning microporous membrane dust collector,in order to make it have the advantages of less influence on filter material by high humidity dust and good dust removal effect.To improve the dust-cleaning effect of the new rotary pulse-jet dust-cleaning microporous membrane dust collector,in this work,the microporous membrane filter plate with new structure used in the new type dust collector is taken as the research object to explore the influence of different influencing factors on the dust-cleaning performance of the filter plate.The results obtained can provide guidance for the future design and application of dust collector.In this work,experiments and numerical simulation methods had been used to study the dust-cleaning performance of the microporous membrane filter plate with new structure.In the dust-cleaning performance experimental research,a new structure of microporous membrane filter plate dust-cleaning performance test bench had been built.Firstly,the effect of pulse-jet pressure on the peak pressure of the wall surface of the microporous membrane filter plate with new structure had been explored,and the filter plate in the dust-cleaning process the wall pressure distribution law had been obtained;then,a powder attachment experiment had been carried out to explore the influence of pulse-jet pressure,pulse-jet distance,dust quality,and dust moisture content on the dust removal rate,and the actual dust removal effect of the filter plate had been obtained,besides,the state of dust removal off the surface of the filter plate during the cleaning process had been captured by a high-speed camera.In the numerical simulation study of dust-cleaning performance,firstly,the appropriate numerical calculation model had been selected,and the accuracy of the calculation model had been verified by comparing the numerical simulation value with the experimental value;then,the influence of pulse-jet pressure,pulse-jet distance,diameter ratio of the end to the inlet of the injection pipe,nozzle diameter and length of filter plate on the peak pressure on the wall of the structured microporous membrane filter plate had been studied.A five-factor three-level orthogonal experiment is designed,and the best cleaning parameters of the new structured microporous membrane filter plate had been obtained after calculation and analysis.The main conclusions are as follows:(1)The comparison between the numerical calculation values and experimental values of the Standard k-ε,RNG k-ε and Realizable k-ε turbulence models show that the error between the Standard k-ε turbulence model and the experimental values is the smallest.The error of each measurement point is less than 15% except for the 欧one measurement point,which is within the maximum allowable error.Finally,the Standard k-ε model is selected as the numerical simulation turbulence model,and at the same time,the accuracy of the numerical calculation model is verified.(2)When the pulse-jet pressure was increased from 0.15 MPa to 0.35 MPa,the average peak pressure on the wall was increased from 513.45 Pa to 1050.49 Pa,and the dust removal rate was also increased from 84.9% to 95.08%;for the peak pressure distribution of the filter plate,the peak pressure of the four measuring points in each column was gradually decreased from top to bottom,and the peak pressure on the narrow side of the filter plate was greater than the peak pressure on the wide side.The numerical simulation results showed that the peak pressure of the filter plate first increased and then decreased from top to bottom,and the maximum value of average peak pressure appeared at 100 mm away from the filter plate opening;when the injection pressure was increased,the pressure at each monitor point on the side wall of the plate and the average peak pressure at the bottom and the average peak pressure of the filter plate was increased accordingly,which indicating that increasing the pulse-jet pressure favors the improvement of the dust-cleaning effect.(3)When the pulse-jet distance was increased from 40 mm to 200 mm,the dust stripping rate increased as the pulse-jet distance was increased,and the removal rate decreased slightly when the pulse-jet distance was increased from 80 mm to 120mm;The numerical simulation results showed that the position of the maximum average peak pressure on the side wall of the filter plate was gradually moved upward with the increase of the pulse-jet distance,and the maximum value of the average peak pressure on the side wall was also gradually increased;The average peak pressure at the bottom and the average peak pressure of the filter plate was also increased;at the same time,as the pulse-jet distance was increased,the area of the area with higher negative pressure at the top of the filter plate was gradually decreased.(4)When the dust quality was increased,the dust removal rate was on a decreasing trend.Exceptionally,when the dust quality was increased from 50 g to 60 g,the dust removal rate was increased slightly;when the dust moisture content was increased,the dust removal rate was decreased from 89.83% to 76.2%,indicating that increasing the dust quality and dust moisture content have a negative impact on the cleaning effect of the filter plate;in addition,it could be found in the images taken by the high-speed camera that as the dust moisture content was increased,the dust attached to the filter plate was mostly peeled off in the form of lumps;the filter material expanded and contracted many times during the pulse cleaning process,causing the dust adhering to the surface of the filter material to break,and then peel off the surface of the filter material to achieve dust removal.(5)In the process of pulse-jet,the pressure distribution of the side wall of the filter plate was different at different moments of blowing,and it changed continuously with the change of blowing time.In the numerical simulation of the diameter ratio of the nozzle end to the inlet end,nozzle diameter,and length of the filter plate,it was found that reducing diameter ratio of the end to the inlet of the injection pipe,increasing the nozzle diameter and reducing the length of the filter plate,could increase the peak pressure on the wall of the large filter plate,so as to effectively improve the dust-cleaning effect of the microporous membrane filter plate with new structure.Through the five-factor three-level orthogonal test,it was found that the nozzle diameter had the greatest influence on the cleaning performance of the filter plate,and the injection height had the least influence on the filter plate;the optimal combination of the cleaning system is as follows: pulse-jet pressure is 0.35 MPa,pulse-jet distance is 200 mm,diameter ratio of the end to the inlet of the injection pipe is 0.40,nozzle diameter is 15 mm,and length of the filter plate is 1200 mm. |
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