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How to select filtration air speed for boiler cloth bag dust filter

cloth bag dust filter
Cloth bag dust filter for fluidized bed boiler with capacity of 15T/h

The cloth bag dust filter is an important equipment to control emissions of coal-fired boilers. Choosing the appropriate filtration air speed for the cloth bag dust filter not only affects emissions standards but also has economic significance in optimizing equipment performance, saving investment and operating costs. onion. This article will introduce the factors to consider when choosing the filtration air speed for a boiler cloth bag dust filter.

1. Effect of filtered air speed on the device

Filtered air speed is an indicator of the air handling ability of the cloth bag dust filter. It is calculated using the formula:

In which, the unit of treated air volume is m³/h, the unit of filtration area is m² and 60 is the unit of second.

Air speed Filtration can be high or low, depending on factors such as dust type, dust concentration, dust temperature, type of filter material and how the ash is cleaned. However, the filtration air speed cannot be chosen arbitrarily, but must consider the following advantages and disadvantages:

  • When the filtration air speed is high, the area can be reduced and filter volume, saving space and investment costs. However, high filtration air velocity can also reduce dust removal efficiency, increase the difficulty of ash cleaning, increase filtration capacity, reduce filter bag life, and increase operating and maintenance costs. maintenance.
  • When the filter air speed is low, it can improve the dust removal efficiency, easily clean the ash, prolong the ash cleaning cycle and the life of the filter bag. However, low filtration air speed can also increase the filtration area and volume, taking up a lot of space and investment costs.

Therefore, choosing the wrong speed Air filtration is a complex job, requiring consideration of many related factors.

 compressed air spray assembly cloth bag dust filter
Pneumatic spray assembly - Inside the cloth bag dust filter .

2. Factors to consider when choosing filter air speed

In designing a boiler cloth bag dust filter, choosing the filter air speed needs to consider the following factors :

  • Emission standards: Emission standards are an important factor to evaluate the effectiveness of cloth bag dust filters. According to different exhaust standards, the filter air speed needs to be adjusted accordingly. If the exhaust gas standard is high, the filter air speed needs to be reduced to ensure effective dust removal. If the emission standard is low, the filter air speed can be increased to save investment costs.
  • Dust type: Dust type is a factor that affects the properties of dust-containing gas, such as dust concentration, dust size, dust humidity, dust viscosity, dust charge and dust toxicity. These properties will affect the ability of the cloth bag dust filter to filter and clean ash. If the dust has high concentration, small size, high humidity, high viscosity, high charge or high toxicity, the filter air speed should be reduced to avoid clogging, adhesion, dispersion or damage. for filter bags.
  • Dust temperature: Dust temperature is a factor that affects the type of filter material and the ash cleaning method of the cloth bag dust filter. If the dust temperature is high, it is necessary to choose a high heat-resistant filter material, such as PPS, PTFE, PI or P84. If the dust temperature is low, it is necessary to choose a filter material that is moisture-proof, anti-corrosion and anti-bacterial, such as PE, PP, PA or PET. In addition, dust temperature also affects the way of cleaning ash, such as compressed air cleaning, vibration cleaning or mechanical cleaning.
  • How to clean ash: The way to clean ash is a factor that affects the performance and lifespan of cloth bag dust filters. The way to clean ash needs to be appropriate to the type of dust, dust temperature, type of filter material and filter air speed. If the ash cleaning method is not suitable, it can cause clogging, adhesion, destruction or loss of durability of the filter bag. There are many different ways to clean ash, such as compressed air cleaning, vibration cleaning, mechanical cleaning, chemical cleaning or thermal cleaning.

broken cloth bag dust filter
The quality of fabric bags is reduced due to working in high humidity conditions

3. Experience in choosing filter air speed for boiler cloth bag dust filter

Based on the factors mentioned, below are some experiences in choosing air speed filter for boiler cloth bag dust filter:

  • According to experience, speed noThe filtration air of the boiler cloth bag dust filter should be selected between 0.6 m/min and 0.8 m/min, to ensure dust removal efficiency and filter bag life. Filtering air speeds that are too high or too low can have negative consequences for equipment and costs.
  • If the dust has a high temperature, it is necessary to choose a filter material that is resistant to high temperatures and proper ash cleaning method, to avoid damaging the filter bag. In addition, it is necessary to check and adjust the dust temperature before entering the cloth bag dust filter, to ensure that the dust temperature does not exceed the tolerance temperature of the filter material.
  • If the dust has high high humidity, it is necessary to choose a filter material that is resistant to moisture and a suitable ash cleaning method to avoid wetting the filter bag. In addition, it is necessary to check and adjust the dust humidity before entering the cloth bag dust filter, to ensure that the dust humidity does not exceed the moisture tolerance of the filter material.
  • If the dust is Small size, need to choose filter material with high filtration capacity and appropriate ash cleaning method, to avoid clogging the filter bag. In addition, it is necessary to check and adjust the dust size before entering the cloth bag dust filter, to ensure that the dust size does not exceed the filter size of the filter material.
  • If the dust is viscous high, it is necessary to choose a filter material with anti-stick properties and a suitable ash cleaning method to avoid sticking to the filter bag. In addition, it is necessary to check and adjust the dust viscosity before entering the cloth bag dust filter, to ensure that the dust viscosity does not exceed the tolerance viscosity of the filter material.
  • If the dust has a viscosity high charge, it is necessary to choose filter material with antistatic ability and appropriate ash cleaning method, to avoid dust dispersion. In addition, it is necessary to check and adjust the dust charge before entering the cloth bag dust filter, to ensure that the dust charge does not exceed the charge tolerance of the filter material.
  • If Dust is highly toxic, it is necessary to choose anti-toxic filter materials and appropriate ash cleaning methods to avoid harming the health of users and the environment. In addition, it is necessary to check and adjust the dust toxicity before entering the cloth bag dust filter, to ensure that the dust toxicity does not exceed the toxicity tolerance of the filter material.