Measures to reduce the resistance of air dust bag filter

1. Reasonably determine the filter wind speed

The resistance of the bag filter depends to a large extent on the filtering wind speed. The resistance of the dust collector structure, cleaning filter bag and dust layer all increase with the increase of the filtering wind speed. No matter what kind of filter material a line-jet pulse bag filter uses, its net filtration wind speed should not exceed 1m/min. For the fine dust layer, since the dust particles overlap each other closely, the filtration wind speed needs to be lower, otherwise the dust will be removed. The running resistance of the device will be greatly increased. However, many dust removal equipment manufacturers maliciously increase the filtration wind speed in order to make their products more competitive in the market competition when selecting models, so as to achieve the purpose of reducing equipment costs. The equipment resistance of this type of dust collector will definitely be higher than the normal value.

2. Reasonable control of airflow rising speed

The airflow rising speed refers to the flow speed of the flue gas in the filter bag space. The airflow rising speed is an important parameter to measure the structural performance of the dust collector, which has a great influence on the performance of the low-pressure line jet pulse bag filter. Under the condition of the same air volume, the airflow rising speed is large, which means that the distance between the filter bag and the filter bag is smaller in the effective bag room space, the filter bag arrangement is more compact, the size of the dust collector is smaller, but the airflow If the rising speed is too large, the running resistance of the dust collector will also increase accordingly. Under normal circumstances, the air flow rising speed is controlled at about 1m/s, which can better exert the performance of the dust collector.

3. Reasonable control of local airflow speed

The local airflow speed of the low-pressure line spray bag filter includes the air speed of the air inlet and outlet, the air speed of the air inlet branch valve, the air speed of the lift valve port, the air speed of the clean air chamber, the air speed of the pattern hole, etc. These wind speeds will have a certain impact on the resistance of the dust collector. . In the design process of the dust collector, we need to increase the size of the air inlet and outlet, the air inlet branch valve port and the poppet valve port as much as possible to reduce the passing speed of the air flow, thereby reducing the operating resistance of the dust collector. The wind speed of the clean air chamber needs to be achieved by raising the height of the clean air chamber, but raising the height of the clean air chamber means an increase in equipment cost, so the selection of the air speed must have a reasonable range. Under normal circumstances, the clean air chamber The wind speed is controlled at 3m/s ~ 5m/s. The wind speed of the flower plate hole is proportional to the length-diameter ratio of the filter bag. The longer the length of the filter bag with the same diameter, the higher the wind speed of the flower plate hole. The length-diameter ratio of the filter bag must be less than 60, otherwise it will not only increase the operating resistance of the dust collector, but also affect the cleaning effect of the filter bag.

4. Evenly distribute the gas flow

Even if the theoretical filtration wind speed and other wind speeds are reasonable in the design of the bag filter, if the airflow uniformity measures are not in place, the actual air volume of each bag room will be high or low; even in a bag room, if If the air distribution measures are not in place, the actual filtering wind speed of each filter bag will be different. Therefore, the air inlet of the dust collector needs to have a gas guide plate and an air equalizing plate, and the opening of the air inlet branch valve needs to be adjusted to balance the air volume of each bag chamber. An air equalizing plate needs to be set in the ash hopper to distribute a single bag. room air volume.

5. Scientifically improve the cleaning effect

The dust layer on the surface of the filter bag has a great influence on the operating resistance of the dust collector, so the cleaning effect is particularly important. There are many factors that affect the cleaning effect of low-pressure line jet bag filter, such as injection pressure, cleaning cycle, filter bag length, and the distance between filter bags and filter bags. Without sufficient injection pressure and energy, the dust layer on the surface of the filter bag cannot be completely removed. However, the injection pressure should not be too large, otherwise the service life of the filter bag will be greatly shortened. The injection pressure needs to be controlled within a reasonable range, and it needs to be flexibly adjusted according to the viscosity of the dust. The injection pressure should be controlled between 0.2MPa and 0.4MPa. From the perspective of reducing the operating resistance of the dust collector, the resistance of the filter bag surface is always the smallest when it is in a clean state, which requires frequent blowing and cleaning of the filter bag, but this is at the expense of the service life of the filter bag. Therefore, in the actual operation process, we need to be flexible according to the concentration of dust in the flue gas and the viscosity of the dust.

Adjust the cleaning cycle.

6. Pre-dust

The rising speed of the resistance of the dust collector is related to the dust concentration in the flue gas. If the dust in the flue gas is collected first through corresponding measures, and then filtered and purified by the filter bag, the filter load of the dust collector can be reduced, and the resistance The rate of ascent will also be greatly reduced. There are many measures for pre-dust removal, such as: adding a cyclone dust collector at the front end of the dust collector or adding a cyclone device inside the inlet of the dust collector to collect dust through the centrifugal effect of the cyclone to achieve the purpose of pre-dust removal; Since the flue gas passes through the ash hopper, due to the sudden expansion of the airflow space, the coarse particles and part of the fine dust will settle down. Therefore, the downward air intake method is recognized as the most scientific air intake method in the bag filter.