Pressure loss and regenerability of nonwoven bag filter materials for cleaning air

Abstract

Mathematical dependences are derived for determining air-cleaning efficiency as a function of the number of filter material regeneration cycles. Filter material with the optimum physicomechanical properties was determined based on an evaluation of regeneration and cleaning efficiency.As dust accumulates on filter elements, their maximum productivity and air-cleaning efficiency indexes and the reliability of the filter elements worsen.Dust removal and dust separation in filters take place on movement of dust-laden gas through the filter material, which is the basic working element in filtration units. For this reason, the productivity, air resistance, cleaning efficiency, and reliability of operation of the filter are greatly dependent on correct selection of the material.To increase the lifetime of filter materials and improve the filtration process, it is necessary to periodically regenerate the filter elements. Regeneration of filter elements consists of applying loads to the dust-laden filter material, which breaks up and separates the dust layer from the material. The most effective method of regeneration is the combination of mechanical shaking and pulsed blowing.We investigated the filtration properties of multiply, regenerable nonwoven bag filter materials of three types, where the linen-weave fabric shell material made of polyester fibres serves as the strengthening element. All samples of the filter bags had a diameter of 260 mm and a height of 400 mm. Their characteristics are reported in Table 1.Standard methods and instruments were basically used to determine the most important characteristics of the filter materials the porosity, thickness, breaking load, elongation at break, and rigidity. The thickness and porosity of the materials were determined with methods developed in the Laboratory of Filtration Systems at the Scientific Auto and Tractor Institute (SATI).The essence of the method of determining the porosity (Π, %) of regenerable nonwoven filter materials consisted of measuring the volume of liquid displaced by the fibres of the materials, and its porosity was calculated for known thickness of the material with the following equation in consideration of the abovewhere m d is the weight of the dry sample, g; m is the weight of the wet sample, g; ρ l is the volume density of the liquid, g/cm 3 ; V is the volume of liquid displaced by the sample, cm 3 . The higher the porosity of the samples, the lower the required excess pressure for separating dust and the more the pressure loss decreased. The results of measuring the physicomechanical properties of the filter materials are reported in Table 2.The filtering and regeneration properties of the filter materials were investigated on a bench unit for testing air cleaners according to GOST 800274.

Efficiencies and Dust Holding Capacities of Textiles Used For Air Filter Applications

“…Porozite ise filtrenin 3 boyutlu hacim boşluk oranıdır ve Eşitlik 10'daki gibi ifade edilir.     1 (10) Burada, poroziteyi,  ise katılığı ifade etmektedir.…”

“…Araştırmacılara göre filtrasyon sürecini iyileştirmek ve filtre malzemesinin ömrünü uzatmak için filtre elemanlarının periyodik olarak yenilenmesi gerekmektedir. Bu amaçla filtre yüzeyinde biriken tozun uzaklaştırılması için birtakım mekanik işlemlerin uygulanabileceğini, bakım yapmanın ve temizlemenin filtre verimliliğine olumlu katkı yaptığını açıklamışlardır [10]. Tanabe ve ark.…”