Bag Filter Bag Spacing Design Standards and Specifications

Basis for Bag Spacing Design

1. Airflow Volume

Airflow volume is one of the important factors affecting bag spacing. A larger airflow volume means that more filter bags are needed to increase the filtration area. In this case, the bag spacing should be appropriately increased to ensure uniform airflow distribution within the dust collector and avoid excessive local airflow velocity, which can lead to increased bag wear or incomplete dust removal. Generally, for every certain percentage increase in airflow volume, the bag spacing should be increased by a corresponding amount. The specific ratio needs to be determined based on actual working conditions and experience.

2. Dust Characteristics

Dust particle size: Coarse dust particles have greater inertia in the airflow and are more likely to directly impact the surface of the filter bags. If the bag spacing is too small, the dust may collide and rebound between adjacent bags, affecting the dust removal effect. For larger dust particles, the bag spacing should be appropriately increased, generally recommended to be no less than 3-5 times the maximum dust particle size.

Dust concentration: High dust concentration will cause the dust layer on the surface of the filter bags to thicken faster, increasing the frequency of cleaning. To ensure effective cleaning and prevent secondary dust dispersion between adjacent bags during cleaning, the bag spacing under high dust concentration conditions should be larger than that under low concentration conditions. For example, when the dust concentration exceeds a certain value (such as 50g/m³), the bag spacing can be appropriately increased by 10%-20%.

Dust viscosity: Viscous dust easily adheres to the surface of the filter bags, forming a thicker dust layer that is difficult to clean. For viscous dust, the bag spacing should be designed to be larger to reduce dust adhesion between adjacent bags and facilitate cleaning operations. Generally, the bag spacing under viscous dust conditions can be increased by 15%-25% compared to ordinary dust conditions.

3. Filter Bag Material

Different filter bag materials have different permeability, strength, and wear resistance. Filter bags with good permeability require a relatively smaller filtration area under the same airflow volume, and the bag spacing can be appropriately reduced; while filter bags with poor permeability require increased bag spacing to ensure airflow. For example, polyester fiber filter bags have better breathability, allowing for relatively smaller bag spacing; while glass fiber filter bags have poorer breathability, requiring a larger bag spacing. Similarly, for filter bags with low strength and poor wear resistance, the bag spacing should be increased to prevent damage from friction between bags during operation.

4. Dust Removal Method

Pulse jet cleaning: Pulse jet cleaning uses compressed air to instantaneously spray the filter bags, causing them to vibrate and remove dust. This cleaning method has a strong force; if the bag spacing is too small, the spray airflow may interfere with adjacent bags, affecting the cleaning effect. Therefore, when using pulse jet cleaning, the bag spacing should be no less than 1.5-2 times the bag diameter.

Reverse air cleaning: Reverse air cleaning removes dust by deforming the filter bags with reverse airflow. Reverse air cleaning has a relatively gentler force, allowing for a smaller bag spacing, but generally it should not be less than 1.2-1.5 times the bag diameter.

Mechanical shaking cleaning: Mechanical shaking cleaning uses a mechanical device to shake the filter bag frame, causing the bags to vibrate and remove dust. This cleaning method has relatively lower requirements for bag spacing, but to ensure the shaking effect and avoid collisions between bags, the bag spacing should also be kept within a certain range, generally not less than 1-1.2 times the bag diameter.

Bag Spacing Design Requirements

1. Minimum Bag Spacing: To ensure normal installation, maintenance, and cleaning operations of the filter bags, and to prevent friction and collision between the bags, the bag spacing should meet the minimum spacing requirements. Generally, the minimum spacing for cylindrical filter bags should not be less than 1 times the bag diameter; for irregularly shaped bags, the minimum spacing should be determined based on their external dimensions and actual installation conditions, but sufficient space should be ensured between the bags for cleaning and to prevent dust blockage.

2. Recommended Bag Spacing: Considering the above factors, the recommended spacing for cylindrical filter bags under general working conditions is 1.5 to 2.5 times the bag diameter. For dust collectors with large air volume, complex dust characteristics, or using high-efficiency cleaning methods, the bag spacing can be appropriately increased to 2 to 3 times the bag diameter.

3. Influence of Bag Arrangement on Spacing:

Row and Column Arrangement: When the filter bags are arranged in rows and columns, the row spacing and column spacing should be consistent or adjusted appropriately according to the airflow distribution. Generally, the row and column spacing can be designed according to the recommended bag spacing to ensure that the airflow passes evenly through each row of bags in the dust collector.

Staggered Arrangement: A staggered arrangement can create a more complex flow path between the filter bags, which is beneficial for improving dust removal efficiency. In a staggered arrangement, the center distance between two adjacent rows of bags should meet certain requirements. Generally, the center distance between the front and rear rows of bags is 1.2 to 1.8 times the bag diameter, and the specific value should be optimized based on dust characteristics and cleaning methods.

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