The working principle of dust filter bag

1. Processing air volume (Q): The processing air volume refers to the volume of gas that the dust removal equipment can purify per unit time. The unit is cubic meters per hour (m3/h) or standard cubic meters per hour (Nm3/h) and is one of the most important factors in baghouse design.

When designing or selecting a bag filter according to the air volume, it is generally not possible to make the filter operate when the air volume exceeds the specified air volume, otherwise the filter bag will be easily blocked, the service life will be shortened, the pressure loss will be greatly increased, and the dust removal efficiency will also be reduced; If the air volume is too large, it will increase equipment investment and floor space, waste resources and not save energy. Reasonable selection of processing air volume is often determined based on process conditions and experience.

2. Operating temperature (℃): For the bag filter, its operating temperature depends on two factors, the first is the maximum temperature of the filter material, and the second is that the gas temperature must be above the dew point temperature. Due to the large selection of glass fiber filter materials, its maximum operating temperature can reach 280 °C. Measures must be taken to cool the gas above this temperature, and measures must be taken to increase the temperature of the gas below the dew point temperature. For the bag filter, the relationship between the operating temperature and the dust removal efficiency is not obvious, which is different from the electrostatic precipitator. For the electrostatic precipitator, the change of temperature will affect the specific resistance of the dust and other effects on the dust removal efficiency.

3. Inlet dust concentration (g/m³): that is, the inlet dust concentration, which is determined by the process of the dust raising point. When designing or selecting a bag filter, it is another important factor after the air volume. , expressed in g/m3 or g/Nm3. For baghouses, the inlet dust concentration will directly affect the following factors:

Pressure loss and cleaning cycles. When the inlet concentration increases, the ash deposition rate on the same filter area is fast, and the pressure loss increases accordingly. As a result, the number of ash cleaning has to be increased.

Wear of filter bags and boxes. In the case of dust with strong abrasiveness, the amount of wear can be considered to be proportional to the dust concentration.

Is pre-dusting necessary? Pre-dust collection is to add another level of dust removal equipment before the entrance of the dust collector, also known as front-stage dust removal.

Ash removal capacity of the ash removal device. The ash discharge capacity of the ash discharge device should be based on the ability to discharge all the collected dust, and the dust volume is equal to the inlet dust concentration multiplied by the processing air volume.

Operation method. The bag filter is divided into two operation modes: positive pressure and negative pressure. In order to reduce the wear of the fan, it is not suitable to use the positive pressure operation mode if the inlet concentration is large.

4. Outlet dust concentration (g/m³): outlet dust concentration refers to the discharge concentration of the dust collector, and the expression method is the same as the inlet dust concentration. The size of the outlet dust concentration should be subject to local environmental protection requirements or user requirements. The emission concentration of the dust collector can generally reach below 30mg/Nm3.