Fabric filters belong to dust control equipment of "dry" type and is one of the most effective types of purification of air with dust high content. Usage of fabric filters is primarily connected with strengthening of the requirements for environmental protection as well as it allows reducing the loss of the finished product with the air outgoing from the drying plant.

Fabric filters in the spray drying plant serve for cleaning or post-treatment of air after the cyclone cleaning. Sanitary norms of the powder concentration in the exhausted air - 10 mg / m3.

The principle of the fabric filter operation is based on dust collection by filter cloth while dust air passes through it.

The filtered powder returns into the production run.

As thickness of the layer of dust on the surface of the bag rises, resistance to the air movement increases and the filter efficiency reduces; in order to prevent this regeneration of dusty filter bags by pulse blowing with compressed air and built-in bags washing system and casing cleaning are provided.

Specifications of the models of filters.
Parameter Value
Filter area, m2 184
Quantity of bags, pcs 156
Filter load, m3/min 2,04
Air consumption at the filter inlet, kg/h 20800
Air consumption on product tank, kg/h 1200
Air temperature on product tank, °С 60
Moisture content, g/kg 40
Dew point of the water steam, °С, 38
Powder concentration at the cyclone inlet, g/m3 10
Powder concentration at the filter inlet, g/m3 1060
Powder concentration at the outlet, g/m3 10
Compressed air consumption, kg/h 50
Air consumption at the outlet, kg/h 22050

 

The filter design includes a cylindrical part with spiral air inlet, an upper air chamber with a perforated plate and an outlet nozzle, conical product tank and a lower chamber with the perforated bottom. Filter bags are fastened in the holes of the perforated plate in the upper chamber. System of pulse blowing with compressed air comprises a set of air pipes with nozzles, high-speed pulse valves and air collectors. The system washing and cleaning includes units of wetting bags and spray heads, fittings and valves for water feed and water discharge.

The dust air enters the cylindrical part of casing and is distributed through gaps between the bags over their surface. The air passes through the cloth; the powder is retained on the surface of the formed layer of the particles.
Regeneration of the filter is carried out by reverse pulse blowing with compressed air.

The compressed air creates back pressure, shakes off the powder and blows filtering cloth. Shacked off powder goes through the product tank to the conical perforated bottom, then under the action of the transport air is discharged through the rotary valve.

Bags washing is carried out in three stages:

  1. The saturation of the cloth with cleaning solution.
  2. The constant supply of cleaning solution and its transport through the cloth under the action of air pressure.
  3. Filter drying by blowing with heated air.

Washing of the tube plate and the casing is carried by means of sliding spray heads.

The air from the upper chamber enters the outlet nozzle and then goes to the fan exhauster.

© Kalinovskiy machine building plant 1934-2017