Theoretical Analysis And Theoretical Analysis Of Filtration Performance Of High Temperature Resistant Composite Filter Media

In recent years, the fog and haze has seriously affected people's daily life, damaged the health of the human body, and given people a wake-up call. One of the main sources of haze is industrial waste gas containing particulate pollutants. The bag filter is widely used in the dust filters. As the emission standards made by the government are more and more strict, the filter performance of the bag filter needs to meet the higher requirements. Filter structure determines its performance. Now the filters resistant to high temperature are composed of several fibers that have different diameters. However, the classical calculation formulas about filtration efficiency and resistance just do the research on single fiber filters. This paper makes explorations in order to get the calculation formulas about filtration performances of composite filters.Firstly, the macroscopic and microscopic properties of several untreated and impregnated felts are tested and analyzed. It aims at understanding how the structure parameters such as filter pore size, porosity influence the performances of the filters. Through testing the structural parameters and performances of the 2 groups of filters, the properties comparison of the untreated felts and impregnated felts and the influences of glass fiber fineness on the properties were obtained. The impregnated felts have smaller average pore size, the larger fracture strength, the lower air permeability and the higher filtration efficiency and the higher filtration resistance than the untreated felts.As the performances of impregnated felts are obviously better than that of untreated felts, impregnated felts are used in the following experiments in order to get simulation equations. With the decrease of the fineness of glass fiber, both the untreated and impregnated felts have the smaller average pore size, the larger fracture strength, the lower air permeability, the higher filtration efficiency and the higher filtration resistance. It turns out that the fiber fineness is an important parameter affecting the filtration performance. However, the average diameter of the filters of composite filters has no physical meaning. So the specific surface area is used instead of the average diameter.The specific surface areas of filters are substituted into Kozeny-Carman equation to calculate filtration resistance.The results are compared with the real filtration resistance.The graph shows that the correlation coefficient R2=92.9%, indicating that the specific surface area is a feasible parameter to calculate the filtration resistance. Then the filtration efficiency of filters are tested under 6 kinds of air speeds. The multiple exponential function is made on the basis of those results. The filtration rate, filling rate, thickness and specific surface area are regarded as independent variables, the filtration efficiency as the dependent variable. And then the parameters of filters are substituted into exponential function to calculate the filtration efficiency. Through comparing the results with the real filtration efficiency, the relative error is found as 0.001%~9.659%. It proves that the specific surface area can be used when calculating the filtration efficiency. Finally the specific surface area instead of fiber diameter is used to improve the classical calculation formulas about filtration efficiency.And then the parameters of filters are substituted into the improved formulas to calculate the filtration efficiency. Through comparing the results with the real filtration efficiency, the relative error is found as 0.008~8.192%. Then the specific surface area instead of fiber diameter is used to improve the classical calculation formulas about filtration resistance. The parameters of filters are substituted into the improved formulas to calculate the filtration resistance.The results are compared with the real filtration resistance.The graph shows that the correlation coefficient R2=91.5%. So the improvement of the classical theory formulas has certain value, and it can be used in the production practice of the composite impregnated felt which is composed of a variety of different fineness fibers.