Dust bag is a high precision, high temperature, abrasion and corrosion resistant filter material made of high performance fiber and high strength scrim as the main raw material, through the process of needling, calendering, burnishing, high temperature shaping, emulsion impregnation and laminating. It can capture dust particles efficiently.

As the core of bag filter, dust removal efficiency is the key. So, for different flue gas conditions, how to choose the raw material, temperature resistance, corrosion resistance and other parameters of the dust bag?

First of all, let's understand the performance parameters of dust bag, mainly including: bag diameter, length, single bag area, grammage, thickness, air permeability, etc.. See the following table for details

Secondly, let's learn more about the main performance test of dust bag.

1、The test of unit area quality

In terms of the same thickness of the filter felt, the change of the unit weight will affect its air permeability and tensile strength. However, the national standard does not specify the value of the mass per unit area size, but the deviation has to do with its provisions. In the test, the sample also has certain requirements: the area of 100cm2 round cake and is located in different parts of the filter bag.

2、Testing of thermal shrinkage

Thermal shrinkage of the filter needle felt has an important impact on the service life of the filter bag. The longitudinal thermal shrinkage of the filter needle felt is large, for the pulse dust collector, often lead to the bag cage is topped out of the flower plate; while the transverse shrinkage rate is large, it will make the bag tighten the bag cage, reducing the ability to clean ash, resulting in increased resistance, and even lead to broken bags.

3, the filter bag tensile strength and tensile elongation test

Tensile strength and tensile elongation is an important indicator of the use of filter bags. According to the requirements of GB/T 6719-2009, ordinary filter needle felt, the requirements of warp tensile strength ≥ 900N, warp tensile elongation ≤ 35%, weft tensile strength ≥ 1200N. weft tensile elongation ≤ 50%.

4、Filtration performance test (VDI test)

Filtration performance test is the basis for filter media selection. By simulating the use of filter needle felt, its filtration efficiency and resistance can be initially evaluated.

Filter needle felt filtration performance test includes clean filter needle felt resistance coefficient, static dust removal rate of filter needle felt, dynamic dust removal rate, dynamic resistance of filter needle felt, regeneration resistance coefficient and dust stripping rate, etc.

5、Determination of filter bag air permeability

When there is a pressure difference between the two sides of the filter needle felt, its performance through the air called permeability, commonly used "permeability" for quantitative measurement. Air permeability refers to the air volume per unit of time, unit area of the flow filter material when a pressure difference of 127 Pa (13 mmH?O) is applied on both sides of the fabric.

Test method: in the test area of 20cm2 of the filter needle felt samples on both sides of the application of 200Pa, record the volume of air flowing through each square decimeter of filter needle felt per minute.

6、Material qualitative analysis

Material qualitative testing using Fourier infrared spectrometer test, different filter needle felt have different characteristics of the only spectrum. Infrared testing of new filter media can judge the material of filter needle felt; infrared spectral analysis of filter media used in the project can judge the oxidation and corrosion of filter needle felt according to the increased functional groups in the spectrum. The use of FTIR testing, from a chemical point of view to analyze the use of filter bags, to provide a basis for the assessment of the filter needle felt life. Comfil testing has advanced FTIR tester, can test all kinds of dust filter needle felt.

7、Scanning electron microscope observation

Scanning electron microscope observation of filter needle felt can observe the morphology of fibers and dust adhesion from a microscopic point of view to judge the use of filter needle felt. When there is a large area of fiber fracture, it can be known that the filter needle felt is subject to serious oxidation and corrosion; when there is more dust accumulation, it can be inferred that the filter needle felt permeability is affected and the dust collector operating resistance may be high. Comfil inspection has advanced scanning electron microscope observer, which can detect all kinds of dust filter needle felt.

8、Other testing contents

In addition to conventional performance testing, there are some special performance tests, such as corrosion resistance, electrostatic properties, hydrophobicity, etc. of filter media. These characteristics are specified in the standard.

通过以上性能检测，可很好地知道所选除尘布袋是否能满足现有烟气工况，从而实现超低排放。

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