The role of the dust layer on the surface of the dust filter bag

The dust layer of the dust bag plays a very important role in the actual dust removal process. The dust layer on the surface of the filter cloth is composed of dust particles of different sizes and has various structural and void properties. Under normal circumstances, it affects the dust removal efficiency and resistance of the bag filter and determines the performance of the operation. The filter cloth is the skeleton that forms the dust layer and supports the dust layer.

1 In the process of filtering and dust removal, the role of the dust layer

(1) When the dust layer is thick enough, high dust removal efficiency can be achieved.

(2) When the dust layer is thin or has many voids, the air permeability is good, and the dust removal resistance and dust removal efficiency are low.

(3) When the proportion of dust is large, the inertia of the dust removal is large, and it is easy to separate from the surface of the filter bag after being shaken, so as to enhance the dust removal effect.

(4) When the viscosity of the dust layer is large, it is not easy to clean the dust, and the resistance is also high.

The degree to which the remaining dust layer enters the inside of the filter cloth or adheres to the surface of the filter cloth directly affects the resistance and dust removal effect of the dust collector.

2 The generation process of the dust layer can be roughly divided into three stages

(1) Within a few minutes or a few hours after the new filter cloth is used, the dust fills the gap of the filter cloth.

(2) After the filter cloth is used for a week or more, the dust should be cleaned several times until a stable residual dust layer is established.

(3) The amount of ash removed from the filter bag each time is approximately equal to the amount of ash deposited on the bag before the next cleaning, and the resistance is the same when the cleaning conditions remain unchanged.

The adhesion in the unstable dust layer is related to factors such as sulfur trioxide, water vapor, calcium or other alkali metal components, particle size and electric charge in the treated flue gas during the dust removal process. High-sulfur fuels are more resistant to filter bags than low-sulfur fuels. With the thickening of the dust layer, the resistance of the filter bag also increases. From the beginning of use to the maximum resistance, the relationship between the two is not completely linear, but there is no sudden change, and it is stable most of the time.