Main application industries and technical scope:

The bag filter is a dry dust removal device. It is suitable for trapping fine, dry and non-fibrous dust. The filter bag is made of textile filter cloth or non-textile felt. The filter function of the fibre fabric is used to filter the dust-containing gas. When the dust-containing gas enters the bag filter, the dust with large and large particles falls into the dust hopper due to gravity. When the gas containing smaller dust passes through the filter material, the dust falls into the hopper. It is blocked and the gas is purified. Generally, the dust removal efficiency of new filter media is not high enough. After using the filter material for a period of time, due to the effects of screening, collision, retention, diffusion and static electricity, a layer of dust accumulates on the surface of the filter bag. This layer of dust is called the primary layer. In the later movement process, the primary layer becomes the main filter layer of the filter material. Depending on the role of the primary layer, the filter material with larger mesh hole can also obtain higher filtration. Efficiency. With the accumulation of dust on the surface of the filter material, the efficiency and resistance of the bag filter increase correspondingly. When the pressure difference between the two sides of the filter material is very large, some fine dust particles attached to the filter material will be squeezed through, which will reduce the efficiency of the bag filter. In addition, the excessive resistance of bag filter will significantly reduce the air flow of the dust removal system. Therefore, when the resistance of bag filter reaches a certain value, it is necessary to clear the dust in time. The primary layer should not be destroyed during ash cleaning in order to avoid the decrease of efficiency.

The structure of bag filter is mainly composed of upper box, middle box, lower box (ash bucket), ash cleaning system and ash removal mechanism.

In addition to the correct selection of filter bag materials, the dust cleaning system plays a decisive role in the performance of bag filter. For this reason, the dust cleaning method is one of the characteristics of the bag filter, and it is also an important part in the operation of the bag filter.

At present, the commonly used cleaning methods are as follows:

1. Gas ash removal: Gas ash removal is by means of high-pressure gas or external atmospheric backflushing filter bag to remove the ash deposited on the filter bag. Gas ash removal includes pulse injection, reverse air blowing and reverse suction air cleaning.

2. Mechanical Vibration Cleaning: Top Vibration Cleaning and Middle Vibration Cleaning (both for filter bags) are used to remove the ash deposited on the filter bags by periodic vibration of the filter bags in turn with the help of the mechanical vibration device.

3. Artificial beating: It is to beat each filter bag artificially to remove the ash accumulated on the filter bag.

The structure types of bag filter are as follows:

1. According to the shape of filter bags, they are divided into flat bags (trapezoidal and flat) and round bags (cylindrical).

2. According to the way of air in and out, it can be divided into two types: downwind, upwind, downwind and direct current (limited to flat flat bags).

3. According to the way of bag filtration, it can be divided into external filter and internal filter.

The fibers used for filter materials are cotton, wool, synthetic and glass fibers. The filter materials woven from different fibers have different properties. The commonly used filter material is 208 or 901 polyester velvet cloth, the use temperature generally does not exceed 120 C, the use temperature of glass fiber filter bags treated with silicone tunnel resin generally does not exceed 250 C, cotton wool fabric is generally suitable for non-corrosive; the temperature is below 80-90 C, dust-containing gas.