Baghouse Filters in Exhaust Systems: Component, Regeneration, Calculations Emissions, Control

Author: Michael Klepik, Chief Executive Officer

Baghouse filters in exhaust systems are devices designed to purify large volumes of dusty air and are widely regarded as one of the most effective methods of filtration.

They are utilized across various industries with significant dust concentrations, including cement silos, asphalt and concrete plants, mineral mining, laser cutting, agriculture, woodworking, food processing, pharmaceuticals, powder coating, chemicals, casting, metallization, rubber, and plastics.

Baghouse emissions, which consist of particulate matter, gases, and other pollutants, are generated during industrial processes. These emissions present significant environmental challenges and require effective filtration and control measures to mitigate their impact on air quality and public health.

The contaminated air entering the cleaning channel undergoes filtration through the installed bags in the chamber, where large-dispersed dust particles settle. The purified air is then reintroduced back into the room.

Baghouse dust collection systems have a simple design yet demonstrate a high degree of air purification.

The baghouse unit comprises:

• A carbon steel housing with coating.
• Supports and a hopper.
• Bags.
• Valves.
• Any additional equipment tailored to specific needs.

The foundation of the air purification system lies in the filter bags, two types: round and flat.

Round filter bags are employed in environments with exceptionally high dust loads and for operations exceeding 3,531,467 cubic feet. They are also suitable for high-volume applications.

Flat filter bags are used when compactness of the entire filter and lower dust loads are required.

The choice of material for bags is made based on the specific task at hand. While fabric is commonly used, non-woven materials are increasingly preferred. These materials possess a homogeneous fibrous fine-pored structure and demonstrate significantly enhanced particle separation mechanisms.

Over time, baghouse filters in the exhaust system accumulate dust and solid waste, resulting in decreased efficiency in air purification. To remove accumulated dirt and restore equipment functionality, several regeneration methods are employed.

Pulse jet cleaning is carried out using compressed air, which is pre-cleaned and supplied in small portions. During pulse jet cleaning, the bags are subjected to aerodynamic impacts directed inward. Compressed air under pressure passes through the entire length of the bags, instantly increasing their diameter and dislodging dust settled on the surface. For longer baghouse, reverse jet cleaning is employed. It is conducted using clean air or gas to remove dust, which is easily dislodged.

To effectively clean the air from exhaust gases, dry dust collectors from the Blizzard series are an excellent choice. This equipment has proven itself to be reliable and highly efficient. Additionally, they feature a modular design, allowing for quick enhancement of system productivity by adding an extra module.

Mechanical vibrational shaking is a prevalent technology for dust removal. The principle involves intense shaking of the elements in horizontal or vertical directions. Contaminated particles settle in the hopper, from which dust is removed using scraper chains, conveyors, or rotary drums. Mechanical vibrational shaking is achieved by impacting rods or through rotational motion with eccentrics. While this method ensures consistent removal of dust sediment, it requires special attention from personnel and necessitates shutting down the filter during regeneration. With this approach, the moving parts of the cleaning equipment wear out faster and require replacement.

Baghouse emission calculations entail a detailed assessment of the pollutants captured. This process involves several steps, including:
• Pollutant Identification: Identifying the types of pollutants, such as particulate matter, volatile organic compounds (VOCs), heavy metals, etc.
• Pollutant Quantification: Quantifying the amount of each pollutant captured by the filtration system over a specific period. This often involves measuring concentrations of pollutants in the inlet and outlet air streams and calculating the difference.
• Filtration Efficiency Evaluation: This is typically determined by comparing pollutant concentrations before and after the filtering process.
• Regulatory Compliance: Ensuring that the emissions comply with environmental regulations and emission standards set by regulatory authorities.
• Monitoring and Reporting: Regular monitoring of emissions and reporting to regulatory agencies to demonstrate compliance with emission limits and to identify any deviations that may require corrective action.

Overall, calculating baghouse emissions is essential for assessing the environmental impact of industrial processes, optimizing filtration system performance, and ensuring compliance with regulatory requirements.

Checking the main parameters of operation:
Temperature control
Exceeding the temperature of the cleaned gases permissible for a specific type of fabric sharply reduces its service life. At temperatures below the "dew point," condensation of moisture is possible, accompanied by the formation of unremovable deposits, or complete loss of gas permeability of the fabric.
Resistance
An increase in hydraulic resistance indicates insufficient regeneration. Resistance decreases due to the destruction of filtering elements.
Dust concentration
With values above 0.001248 PCF, it is advisable to have a pre-filtering stage for coarse dust before the filters.
Regeneration
Check the operation of the shaking mechanism for cleaning and the reverse air blowing mechanism of the sleeves with clean air:

• Clear periodicity of shaking: the number of hammer blows and the shaking period are determined individually for each type of baghouse;
• Mandatory compliance with sectionality of shaking and blowing;
• Duration of pulses during impulse regeneration with compressed air (should be 0.1 - 0.2 s);
• Compliance with the design blowing pressure of the sleeves (specifically for each type of air purifying elements).

In 2020, in the United States, over 50 million tons of carbon dioxide were emitted into the atmosphere from various sources, including vehicles, power plants, and industrial facilities. Investing in a baghouse exhaust system will provide your business with highly efficient emissions filtration, contributing to reducing harmful environmental impacts and complying with environmental safety standards.

Advantages of Torch-Air baghouses:

1. High efficiency. Gas cleaning from dust up to 99.9%.
2. Versatility. The ability to clean at any gas pressure, at any concentration of suspended dust particles, at high temperatures.
3. Durability. Chemical-resistant materials are used.
4. Ease of control. Full process automation is possible.
5. Reliability. All filters comply with environmental safety standards.

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