Air inlet method of bag filter

The air inlet mode of the bag filter can be divided into three modes: upper air inlet, lower air inlet and side air inlet.

1. Upper air inlet method

Dust-laden gas enters from the top of the filter bag and exhausts from the bottom. The dust sedimentation direction in the dust-containing flue gas is the same as the flue gas movement direction. The upper inlet bag filter has a better effect in processing aerosols (<3μm) containing more ultrafine dust, and the equipment resistance is small. However, it is difficult to adjust the tension of the filter bag because of the complicated structure and complicated structure. There is stagnant air in the ash hopper, which is easy to accumulate ash, there will be water vapor condensation, and it is inconvenient to clean the ash. Therefore, most bag filter designs do not adopt this method.

2. Bottom air inlet method

Dust-laden gas enters from the lower part of the box and exhausts from the upper part. Due to the sudden diffusion of the airflow, the flow velocity drops suddenly, and a part of the dust with larger particles falls directly into the ash hopper under the action of gravity. Therefore, the wear of the filter bag and the deposition of dust particles on the filter bag are reduced, and the dust cleaning interval is prolonged. However, when the reverse blowing method is adopted, the sedimentation direction of the particles to be cleaned is opposite to the direction of the cleansing air flow, which hinders the settlement of smoke and dust, and will produce “secondary dust”, which will affect the cleaning effect.

3. Side air inlet method

The dust-containing gas enters the dust collector from the side of the box, and then enters into the side through the flue gas distribution device to evenly distribute the dust-containing gas, which can coarsely separate large-diameter solid particles. However, due to the lateral impact of the airflow on the filter bag, the filter bag is impacted and worn, and the service life is shortened. Some large-scale dust collectors are longer, and the airflow distribution along the way is uneven, the working conditions and load of the front and rear filter bags are uneven, and the load and wear of the front filter bags are more serious. Therefore, in order to extend the time interval between filter bag replacement and reduce costs during maintenance, the positions of the front and rear filter bags should be changed at regular intervals so that the impact of the dusty gas on the filter bag and the filter load are as balanced as possible.