How to choose bag dust collector filter bag? 7 model selection principles and 2 types of model selection basis, correct selection will improve dust removal efficiency

The filter bag is the core filter component of the bag dust collector, and its cost is about 10% to 15% of the equipment cost. The filter bag material used to make the filter bag directly determines the performance parameters of the bag dust collector, such as the specifications of the dust removal equipment, dust removal efficiency, emission concentration, running resistance, and service life. Therefore, it is very important to use the filter bag correctly and properly.

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Principle of filter bag selection

Filter bag is generally selected according to the nature of dust-containing gas, dust and the cleaning method of the bag dust collector. The following principles should be followed when selecting.

(1) Reasonable structure and high collecting ratio ;

(2) Good stripping, easy to clean ash, non-fouling performance;

(3) Appropriate gas permeability, low resistance and high filtration precision;

(4) has sufficient strength and good dimensional stability;

(5) It has good temperature resistance, chemical corrosion resistance, oxidation resistance, hydrolysis resistance and wide adaptability;

(6) Wide range of raw materials, stable and reliable performance;

(7) Low price and long life.

Selection according to the characteristics of filter material 

Common use filter material peculiarity and parameters

Filter material name

Terylene punched felt

Nomex

Fiber glass

P84

Chemical name

Polyester

Aramid

Polyimide

Mass area ratio (g/m2)

500

500

450-900

500

Thickness (mm)

1.95

2.3

0.46

2.4

Strength (warp)(N)

1020

950

2100

600

Strength(weft)(N)

1350

1000

1400

800

Elongation(warp)(%)

23

27

3

Elongation(weft)(%)

30

38

3

Permeability

19.8

40

20

Usage temperature

130

200

260

240

Flash temperature

150

250

260

260

Acid resistance

good

common

excellent

excellent

Alkali resistance

common

good

excellent

common

Polyester

Polyester filter materials are usually used in low temperature applications. Under normal circumstances, no film is required. Only when the discharge requirement is less than 30 mg/Nm3, or when the dust is very fine and the humidity is high, the lamination is considered.

PTFE

Polytetrafluoroethylene (PTFE), also known as Teflon, is stretched into a strong microporous material with a pore size of 0.1μm to 2.0μm and a porosity of more than 80%. It has excellent chemical resistance in sulfuric acid. , Sodium hydroxide and the strong corrosive agent in the atomic industry, uranium pentafluoride will not corrode, and can withstand cold and heat. It can be used for a long time at -200 °C ~ 250 °C, and has good electrical insulation and smooth surface character. Teflon filter materials are often treated by coating or needle punching to improve dust removal efficiency and extend service life.

Nomex

Nomex filter material can be used in applications where the temperature is high and the dust particles are coarse. Nomex has good high temperature resistance, is more resistant to folding than glass fiber, can use higher injection pressure, and can air blast more filter bags with the same pulse valve.

P84

P84 filter bag has lower temperature resistance than glass fiber and has good acid and alkali resistance. However, because its special fiber structure is usually not coated, the filtration efficiency is not as good as that of the membrane filter bag, but it is expensive.

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Choose according to the nature of the dusty gas

1. Gas temperature

The temperature of the dusty gas is an important factor in the selection of the filter bag. Generally, the dust-containing gas of less than 130 °C is called normal temperature gas, and the dusty gas of more than 130 °C is called high temperature gas, so the filter bags can be divided into two categories: normal temperature filter bags below 130 °C and High temperature filter bag above 130 °C. Therefore, the appropriate filter bag should be selected according to the temperature of the flue gas. In actual work, some people call 130-200 °C gas as medium-temperature gas, but filter bags are more high-temperature type.

2. Gas humidity

The dust-containing gas is divided into three states according to the relative humidity: when the relative humidity is 30% or less, it is a dry gas, the relative humidity between 30% and 80%, it is general gas and the relative humidity of the gas 80% or more, which is a high-humidity gas. When the high-humidity gas is in a high temperature state, especially when the dust-containing gas contains SO2, the gas cooling causes dew condensation. This not only causes fouling and clogging on the surface of the filter bag, but also corrodes the structural material, so special care is required.

The following points are noted when selecting filter bag for wet gases:

(1) The moisture-containing gas causes the dust trapped on the surface of the filter bag to be wet-bonded, especially for water-absorbing, deliquescent and moist dust, which may cause a paste bag. For this reason, filter bags with smooth surface and long fiber easy to clean such as chinlon and glass fiber should be used, and silicone oil and fluorocarbon resin should be used for impregnation of the filter bag, or acrylic or PTFE should be used on the surface of the filter bag. The substance is coated. The sinter board and the coating material have excellent moisture resistance and easy dust cleaning performance, and should be preferred as high humidity gas.

(2) When high temperature and high humidity are present at the same time, it will affect the temperature resistance of the filter bag, especially for materials with poor hydrolytic stability such as chinlon, polyester and amide, which should be avoided as much as possible.

(3) For the design of the filter bag, the circular filter bag should be used for the moisture-containing gas. The flat filter bag and the diamond filter bag (except the sinter board) with complicated shape and very compact arrangement are not used as much as possible.

(4) The inlet temperature of the dust-containing gas of the precipitator should be higher than the dew point temperature of the gas by 10 to 30 °C.

3. The chemical nature of the gas

In various furnace kiln flue gas and chemical waste gas, it often contains various chemical components such as acid, alkali, oxidant and organic solvent, and is often affected by various factors such as temperature and humidity.

Therefore, when selecting a filter bag, it is necessary to grasp the main factors according to the chemical composition of the dust-containing gas for comprehensive consideration.

In addition, when selecting the filter bag, the dust property and the dust cleaning method of the dust collector should also be considered, and the matching and selection between their mutual relation and own characteristics should be carried out to ensure the selection of a suitable filter bag to ensure the dust removal quality.

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Post time: Mar-24-2019
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