Analysis of the causes of filter bag shedding

Step 1 Wear and tear

1.1 Uneven air distribution

The uneven distribution of air flow causes the dust gas to scour the part of the filter bag at high speed, which makes the local wear of the filter bag and reduces the service life.

Preventive measures: To improve the uniformity of the air distribution of the equipment, each project should do computer numerical simulation or physical simulation test on the air distribution, respectively, to verify the rationality of air intake mode, chamber mode, arrangement mode and other aspects.

1.2 The dust filtration speed is high

High dust filtration speed will cause frequent dust removal, the fabric fiber of filter bag especially the glass fiber is easy to be damaged.

Preventive measures: Choose the appropriate speed of dust filtration, and try to avoid high filtration wind speed. According to the operating experience at home and abroad, the use of PPS or base cloth using PTFE and other composite fabric filter bag, bag filter filter wind speed generally choose ≤1.0m/min, electrostatic precipitator + bag filter can choose 1.2 ~ 1.3m/min, For the bag type dust collector with high dust concentration, viscosity and humidity, it is appropriate to choose 0.8 ~ 1.0m/min.

1.3 The filter bag interval is too small

When the filter bag interval is too small, the outer wear of the lower part of the filter bag is a more common phenomenon. Most wear on one side, the bottom of the most serious, gradually reduce upward, local sewing thread will be worn off.

Preventive Measures:

(1) Ensure that the flatness of the flower plate is within a reasonable range;

(2) Select appropriate hole spacing and cage bones with automatic centralization function to avoid collision and friction between adjacent filter bags.

1.4 Film shedding

Due to the quality of the film or the high-speed erosion of the air flow, resulting in the surface of the film coated filter material wear and even film shedding.

2. Corrosion

The most obvious characteristic of corrosion damage is that the strength of the filter bag decreases significantly overall. The main manifestations in the dust removal are acid corrosion and oxidation corrosion, which leads to the loss of the load that the filter bag can bear, and thus the loss of filtration performance and failure.

2.1 Acid corrosion

If the content of sulfur oxide in smoke is high, the acid dew point temperature is also high. Especially when the smoke temperature is reduced under low load operation, the SOX content in the flue gas will increase and the acid dew point will also increase due to the large excess air combustion coefficient. Once the smoke temperature is lower than the acid dew point, the acid condensation produced has a strong corrosive effect on the filter bag.

Preventive Measures:

(1) Control the operating temperature of dust above the acid dew point;

(2) Select the composite material with PTFE substrate and PTFE and PPS mixed in a certain proportion;

(3) Do a good job of dust collector inlet flue and shell insulation.

2.2 Oxidation Corrosion

Oxidative corrosion refers to the nitrogen oxides, oxygen, ozone and other oxides in the flue gas caused by the damage to the filter material. The appearance of PPS fiber is dark and brittle, the appearance is intact, but the strength drops sharply, even only 200 ~ 300N.

Preventive Measures:

(1) Select the filter material with good oxidation resistance according to the actual working condition, such as PTFE or P84;

(2) Reduce oxygen content as far as possible to avoid and reduce the contact between PPS filter material and ozone and other oxides;

(3) Do a good job in the sealing design of the dust collector shell to minimize the rate of air leakage;

Step 3 Jam

The clogging failure mainly includes dust clogging, oil mist clogging and condensation paste bag.

3.1 Dust Blockage

In the filtration process, fine dust can enter the fiber interlayer of the filter bag, but it is impossible to blow all the dust that has invaded the inside of the filter bag out of the outside of the filter bag. Therefore, after years of operation, the residual resistance of the filter bag will continue to increase. In addition, low load dust collector running for a long time not clear ash will also lead to this problem.

3.2 Oil mist blockage

Oil mist blockage is mainly caused by the failure or lack of protective measures for the filter bag when the equipment is started or oil is thrown to fuel combustion in low-load operation, which will also lead to the increase of residual resistance of the filter bag, even if it is difficult to solve this problem by using strong ash cleaning.

3.3 Condensation paste bag

Condensation refers to the phenomenon of saturated moisture precipitation of moist gas under certain pressure and temperature. The temperature point at which water is precipitated is called the dew point.

Dew-forming paste bag is mainly caused by the dust collector running below the acid dew point, and the condensed acid is attached to the outer surface of the filter bag. This phenomenon is mainly caused by the excessively low temperature when the equipment is started or operated. When the equipment has a large area of pipe explosion, condensation paste bag will also occur. Either acid condensation or normal condensation will lead to an increase in the inherent resistance of the filter bag.