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Home / Blog / Baghouse Design: 12 Easy Steps and Calculation

Baghouse Design: 12 Easy Steps and Calculation

Author: Michael Klepik, Chief Executive Officer

Principles of Baghouse Design: 12 Easy Steps

Designing and sizing a dust collection system is essential for maintaining a clean and safe work environment in industries where particulate matter is generated.

To ensure optimal functionality and compliance with environmental regulations, engineers must carefully consider specific baghouse design criteria, including gas stream requirements, particulate matter characteristics, emission standards, and etc. Understanding baghouse design parameters is crucial for optimizing filtration efficiency and equipment longevity. For a comprehensive guide on structuring and scaling your setup, consult the 'baghouse design handbook,' which outlines 12 essential steps in the engineering process.
How does a Bag Filter work

Step 1: Identify the Dust Source

Determine the location and nature of pollution-producing processes in your facility.
Consider the type and size of dust particles generated, as this will influence the selection of filtering fabric and the baghouse system design.

Step 2: Calculate Dust Load

Measure the emission rate of the contaminated stream in pounds per hour or kilograms per hour. Consider the dust's characteristics, such as particle size, density, and concentration in the gas stream.

Step 3: Determine the Required Airflow (CFM)

Calculate the required airflow by dividing the particulate load by the characteristics of the fine particles. The formula is:
Required Airflow (CFM) = Dust Load (lb/hr)Dust Density (lb/ft3) × Dust Concentration (gr/ft3)

Step 4: Select Filter Media

Choose appropriate material based on the type and size of contaminant particles. Common media options include woven or felted fabrics made of materials like polyester, polypropylene, or PTFE.

Step 5: Design of Baghouse Filter

Determine the number and size of bags necessitated. The size and shape should be optimized for the specific application.
The advantage of a long bag design in baghouses is significant, primarily due to the increased area for particulate capture, leading to enhanced efficiency and the potential for reduced network loads and energy costs.
Select an equipment type (e.g., pulse-jet, reverse-air, shaker) based on your operational needs and the type of particulate being collected.
Consider factors like temperature, moisture, and chemical compatibility when selecting components.

Step 6: Filter Installation Methods

Let's consider the method of filtration element installation and replacement, with one approach being the baghouse filters bottom loading technique. This aspect is crucial for maintenance ease, operational efficiency, and ensuring worker safety. Three primary options:

  • Bottom Loading
This method is often used in scenarios where there is insufficient space to allow for top loading. Bottom loading may necessitate personnel ingress into the unit (confined space entry), calling for stringent compliance with safety protocols.

  • Top Loading
This baghouse filter design is more common and generally preferred because it typically does not necessitate workers to enter the structure, making the process safer and more efficient.

  • Side Loading
This approach is beneficial in facilities with constraints that limit access from the top or bottom.

Each method in a baghouse design example has its considerations regarding space, safety, and maintenance demands, and the choice between them can also be influenced by the specific layout and needs of the plant or facility.

Step 7: Calculate the Total Filtration Area

To ensure optimal performance and efficiency in a air cleaning equipment, engineers utilize baghouse design equations, specifically focusing on calculating the total filtration area needed by applying formulas that consider factors such as required airflow, air-to-cloth ratio, and efficiency.
Total Filtration Area (ft2) = (Required Airflow (CFM) * Air-to-Cloth Ratio) / Baghouse Efficiency
The air-to-cloth ratio is a engineering parameter that depends on the type of filter media and the specific application. Typical values range from 2:1 to 4:1.
Total Filtration Area (ft2) = Required Airflow (CFM) * Air-to-Cloth RatioBaghouse Efficiency
The air-to-cloth ratio is a engineering parameter that depends on the type of filter media and the specific application. Typical values range from 2:1 to 4:1.

Step 8: Size the Baghouse

Select a gas cleaning equipment with an adequate number of bags and the necessary filtration area to meet your calculated gas stream needs.
Consider redundancy and future capacity demands in your selection.

Step 9: Determine Fan Size and Type

Size the exhaust fan to generate the essential air flow, maintaining the desired capture velocity at the particle source and overcoming system resistance.
The selection of a particular fan type in baghouse fan design depends on several factors, including the properties of the polluted gas, the necessary pressure levels, the volume of gas stream, and various other specifications Below are the main types of fans:

  • Centrifugal fans (Centrifugal blowers):
These fans use rotation to transfer kinetic energy to the current, increasing its speed, which is then converted into pressure. They are ideal for handling large volumes of the stream at high static pressures.
Depending on the application, various configurations of centrifugal fans can be chosen, such as radial, forward-curved (with blades tilted forward), or backward-curved (with blades tilted backward).

  • Axial fans:
Axial fans are suitable for handling large volumes of flow at relatively low pressure. They operate by propelling the stream along the axis of the fan.
They are often used when a substantial air volume is needed without high pressure, although they are not always the optimal choice for configurations with demanding static pressure criteria.
The choice between these types of fans and their configurations depends on the particular demands of your aspiration setup and application. Centrifugal fans are most often used due to their ability to handle various loads and gas treatment conditions, as well as the ability to overcome high static pressures.

Step 10: Ductwork and Hooding Engineering

Plan the ductwork to transport the dust-laden gas from the source to the cleaning unit efficiently. Use properly constructed hoods and enclosures to capture airborne solids at the source and minimize fugitive emissions.

Step 11: Include Safety Measures

Incorporate safety features like explosion vents or suppression mechanisms if you have combustible dust present.

Step 12: Maintenance and Monitoring

Establish a regular maintenance schedule to replace bags, inspect and clean the apparatus, and ensure it operates efficiently.
Install monitoring equipment (e.g., pressure gauges, differential pressure sensors) to continuously assess the setup's performance.

Inlet Configuration Essentials

The setup of the intake area is crucial because it significantly impacts the efficiency and performance of the filtration process. Here are a few key considerations for baghouse inlet design:

  • Flow Distribution
The inlet design should ensure a uniform distribution of particulate-laden gas throughout the purification system. Inadequate configurations can result in an unequal distribution, causing certain areas to become congested with particulates, while others are not fully utilized. This can significantly reduce the overall efficiency of the arrangement.

  • Inlet Velocity
Excessively high velocities can cause undue abrasion and early deterioration of the purification elements, while overly low speeds may result in dust settling inside, leading to operational inefficiencies and a heightened risk of fire.
  • Dust Particulate Characteristics and Temperature Considerations
Understanding the characteristics of the particulates (size, shape, density, etc.) being collected is necessary for the proper entry point configuration. Certain particulates may require preliminary segregation before passing through the purification unit, which can be accommodated by specific entry designs.
For certain applications dealing with high-temperature gases, the inlet architecture must also consider the temperature of the gases entering the apparatus to avoid any damage to the components.

  • Pre-separation Chamber
Occasionally, a pre-separation chamber or baffle is employed at the entry point for the initial separation of heavy or large particulates. This feature aids in diminishing the load on the subsequent purification stages and offers additional protection against potential damage.

  • Inlet Duct Layout
The configuration of the ductwork leading to the equipment inlet should minimize areas of turbulence because turbulent flow can cause particulate to drop out of the stream and build up within the ductwork. Smooth, laminar flow is desirable as it helps in keeping the particulate suspended within the gas stream.

A thoughtfully engineered entry zone contributes significantly to the equipment's overall performance and longevity.

Modular Design

The modular design of baghouses is a contemporary and convenient solution for air aspiration tasks. A multi-section system is composed of several modules. The addition of modules enhances overall performance, increases the volume of gas cleaned, alters dimensions, and induces changes in technical specifications.
Quick performance upgrade
Increase productivity by adding an additional filtering module.
Easy and fast installation
The assembly of large nodes with bolted joints is done following instructions, similar to furniture assembly. No welding or complex manipulations are needed.
Simple and fast transportation
Thanks to its modular architecture, the delivery of the aspiration purification setup does not necessitate special transport and is less time-consuming.

Calculation of Basic Parameters

Formulating a gas cleaning equipment entails various calculations to ensure effective and efficient performance. These calculations involve several factors, including air volume, dust load, particle size, and others. Below are key steps and formulas often used in the baghouse filter design calculation:
1. Air-to-Cloth Ratio (A/C ratio): It determines the amount of cloth area (filtration media) required to filter the air volume, directly influencing the element's efficiency and the pressure drop across the system. Formula:
A/C ratio = Air Flow Rate (CFM)Total Cloth Area (ft2)
2. Total Cloth Area: Based on the air-to-cloth ratio, you calculate the total filtering fabric area needed. Formula:
Total Cloth Area (ft2) = Air Flow Rate (CFM)A/C ratio
3. Number of Bags: Once you know the total cloth area, you can determine the required quantity. This depends on the individual bag's cloth area. Formula:
Number of Bags = Total Cloth AreaCloth Area per Bag
4. Interstitial Velocity refers to the upward velocity of the gas passing between the bags, playing a crucial role in minimizing the re-entrainment of particles.Formula:
Interstitial Velocity = Air Flow Rate (CFM)Cross-sectional area of the baghouse (ft2)
5. Pressure Drop Calculation: An essential aspect of the system's efficiency and energy consumption, the pressure drop across the filtration components needs to be calculated and minimized as much as possible.

These baghouse design calculations necessitate precise data pertaining to the operational environment, particulate types, gas conditions, and anticipated outcomes. Using these parameters, engineers can devise a framework optimized for efficiency, effectiveness, and regulatory compliance. Computer simulations and software are often used for more complex systems to predict performance and assist in the planning process.

We strictly comply with all established baghouse design standards during the manufacturing of our aspiration equipment.
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We always make extremely precise calculations and provide assistance in choosing the optimal cleaning systems, which usually takes 1 to 2 days.
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Vladimir Nikulin
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