Analysis of the cause of filter bag clogging in the bag dust collector:
The main reason for the blockage of the filter bag is that the filtration speed is too large, the dust is too fine, the dust is sticky, the filter bag is poorly cleaned, and the filter bag is damp.
If the the filtered gas velocity of precipitator operated surpassing design standard of filter bag is extremely likely to cause the fine dust in the exhaust gas to get stuck inside the filter bag fiber. As a result, the filter bag is clogged.
It is a good method to use a membrane filter or to pre-coat a protective powder layer on the surface of the filter bag. For viscous dust, it is necessary to reduce the filtration gas velocity, or increase the pressure of pulse injection, or use offline pulse cleaning filter bag, but the better method is to increase the filtration area to reduce the filtration gas velocity and extend the life of the filter bag.
Poor cleaning of the filter bag mainly includes frequent cleaning and excessively long cleaning time. If the frequency of cleaning is too often, the fibrous structure of the filter bag is loosened to increase the fine dust in the exhaust gas to block the filter bag. If the cleaning time is too long, the initial powder layer on the surface of the filter bag is washed away.
If the cleaning time is too short and the dust on the surface of the filter bag has not been completely cleaned, the filtration will begin, and the dust will gradually accumulate on the surface of the filter bag, causing the filter bag to become clogged. In solving this problem, it can be adjustments through several times of test run.
The reason why the filter bag is damp: the dust collector shell is leaking because of untight seal and enters the humid air. The compressed air used for reverse flow cleaning is not clean (containing oil, water), and the compressed air used for dust cleaning is too cold.
In order to prevent the filter bag from getting damp, in the cold area, the compressed air used for dust cleaning can be adding heat preservation, warming, degreasing and water removal, and then continue to clean the dust for 10~20 minutes after the dust collector stops.
Moisture is the biggest cause of clogging of the filter bag. The cause of moisture is usually condensation at low temperature, especially when dealing with burning or high-temperature flue gas. The following methods can be used to prevent such cases:
1. Avoid improper starting up
2. Avoid starting when the resistance of the precipitator is large; Turn on when it is lower than the dew point;
When the surface of the filter bag has condensed water after the dust collector is shut down, it is restarted. In this case, a large amount of dusty air will be entered, and with high humidity will cause the surface of the filter bag to be muddy.
In order to prevent this, the dusty air at the inlet of the precipitator should be preheated or pre-coated dusting layer .
3. Start up at lower than dew point
The dust collector is running below the dew point, which is prone to problems. If the air intake is unevenly distributed, it is likely to cause local corrosion of the dust collector housing. Therefore, the dust collector should be prevented from working below the condensation point, and the heat preservation device should be used.
4. Air infiltration
Air infiltration often occurs in the dust collector’s flange, access door or dust collector’s moving device. If the seal is not tight, the outside air enters the dust collector. When high-temperature exhaust gas is treated, a low-temperature zone is generated inside the dust collector, which causes condensation at low temperature zone, then corrodes the dust collector, and causes moisture in the filter bag.
5.Improper gas distribution
If the inlet gas of the precipitator is unevenly distributed, the resistance will be greater when the precipitator is turned on. Therefore, the intake air distribution of the precipitator should be uniform.
Post time: Mar-31-2019