Which method is better for positive pressure or negative pressure of a bag filter?
The question of which method is better for positive pressure or negative pressure of bag dust collectors has always been a concern for customers. In terms of price alone, although the positive pressure type of dust collector is cheap, the dust removal effect is not satisfactory, while the negative pressure type of dust collector is relatively expensive, but the dust removal effect can be achieved in one step. So there are differences in the positive and negative pressure structures of bag filters. Here, Botou Tianrun Environmental Protection will provide a detailed explanation for everyone:
1、 The structural characteristics of the negative pressure type bag filter:
1. Structure setting: The negative pressure bag dust collector is installed with an induced draft fan at the outlet of the purified gas in the dust collector. The flue gas containing dust or corrosive substances are introduced into the dust collector through negative pressure for purification, and the purified gas is passed through the fan. General dust concentration_ Over 3g/m ³， Dust with coarse particle size, strong grinding ability, and high hardness are all selected as negative pressure type.
2. Structural features:
1) Due to the installation of the bag filter in front of the ventilation fan, the gas flowing through the fan has been filtered and dust removed with low dust concentration, greatly reducing the wear resistance of the fan and extending its operating life. When dealing with high initial concentration of dust containing gas, we usually use a negative pressure dust removal system.
2) Place the bag filter and pipeline in the negative pressure section of the ventilation fan, which can easily inhale air and cause air leakage. The air leakage rate of the negative pressure dust removal system is generally 5% to 10%, which increases the air volume of the ventilation fan and increases power consumption.
3) In the design and selection of negative pressure dust removal systems, other measures should be taken to minimize air leakage in the dust collector and pipelines as much as possible to ensure the good operation of the dust collector.
2、 The structural characteristics of the positive pressure type bag filter:
1. The positive pressure type (also known as pressure in type) dust collector has a higher internal gas pressure than atmospheric pressure. The positive pressure type dust collector's induced draft fan is installed at the inlet end of the dust containing flue gas in the dust collector, generating positive pressure inside the dust collector wall. It is easy to introduce dust or corrosive flue gas into the dust collector, making it difficult to install indoors and handle highly toxic dust containing flue gas.
2. Structural features:
1) The positive pressure dust collector is prone to dust wear on the fan impeller and casing due to the dust containing gas flowing through the fan not being purified by the dust collector. Therefore, the positive pressure dust removal system can only be used under conditions where the gas dust concentration is less than 3G/m3, the dust wear resistance is weak, and the dust particle size is small.
2) The dust collector is located in the positive pressure section of the ventilation fan. There is no need to consider the additional air leakage rate of the dust collector, and the mechanical and electrical consumption of the ventilation fan is low.
3) The shell structure of the dust collector is simple, such as the shell structure of a positive pressure bag filter, as long as it is rainproof and does not need to be sealed; Equipment manufacturing and installation are simple and cost-effective.
4) In the positive pressure dust removal system of a bag filter, purified gas is directly discharged into the atmosphere from the dust collector and smokeless chimney. The dust collector has a noise reduction effect, and there is no muffler on the outlet side of the fan, which is beneficial for saving land and investing in the dust removal system in the early stage.