How to Detect and Resolve Air Leaks in Dust Collectors

Pulse jet baghouse dust collectors are widely used in industrial production, with their operational effectiveness directly impacting dust emission concentrations and equipment stability. Air leakage represents a common yet severe operational hazard in baghouse systems. Once leakage occurs, it not only reduces dust removal efficiency but may also lead to flue gas condensation, filter bag clogging, equipment corrosion, and even cause dust emissions to exceed regulatory limits. This paper provides a systematic analysis of air leakage hazards, common causes, detection methods, and remedial measures.

I. Hazards of Air Leakage in Dust Collectors

1. Reduced Dust Removal Efficiency

Air leakage allows external cold air to enter the dust collector, altering the airflow distribution. This causes some dust-laden gas to bypass the filter bags and enter the clean air chamber directly, ultimately resulting in dust emissions exceeding standards.

2. Causes Condensation and Bag Clogging

When cold air mixes with high-temperature flue gas, localized temperatures may drop below the dew point, causing moisture condensation. This leads to bag clogging and dust caking, severely impairing cleaning efficiency and air permeability.

3. Increases System Resistance

Air leakage alters flow paths, creating uneven gas distribution. This places excessive load on specific filter bags, resulting in elevated resistance.

4. Equipment Corrosion and Damage

Condensate combines with acidic gases to form corrosive solutions like sulfuric acid and hydrochloric acid, eroding the housing and filter bags.

5. Increased Energy Consumption

Air leakage boosts system air volume, increasing induced draft fan load and energy consumption.

II. Common Causes of Air Leakage in Dust Collectors

1. Improper Welding Seams or Flange Seals

Poor welding quality during manufacturing or installation, or aging flange gaskets, can lead to air leakage.

2. Inadequate Sealing of Inspection Doors and Sight Gauges

Aged sealing strips, improper installation, or door deformation can easily cause air leakage.

3. Air Leakage from Ash Discharge Valves or Hoppers

Poor sealing of discharge mechanisms or cracks in ash hoppers allow external air to infiltrate.

4. Improper Filter Bag Installation

Inadequate sealing between bag openings and perforated plates, or detached filter bags, cause airflow short-circuiting.

5. Air Leaks at Duct Connections

Poor connections between inlet/outlet ducts and the dust collector housing, coupled with insufficient sealing measures, result in air suction through gaps.

III. Air Leak Detection Methods

1. Negative Pressure Detection Method

During system operation, noticeable air suction occurs around leak points. Detection can be performed using a handheld negative pressure detector or anemometer.

2. Smoke Test Method

Release smoke (e.g., safety smoke sticks) outside the dust collector. If smoke is drawn into the housing, it indicates a leak point exists.

3. Infrared Thermal Imaging Method

Scan the housing surface with an infrared thermal imager. Leakage areas are easily identified due to noticeable temperature differences.

4. Differential Pressure Analysis Method

Compare theoretical airflow volume with actual operating resistance. Abnormally low resistance indicates potential air leakage.

5. Dust Concentration Monitoring Method

By monitoring the discharge concentration at the outlet, a sudden increase in concentration without significant changes in system conditions may indicate air leakage causing airflow short-circuiting.

IV. Solutions for Air Leakage Issues

1. Enhance Design and Manufacturing Quality

• Adopt fully welded structures or high-quality sealing flanges to prevent weld defects.

• Conduct airtightness tests on housings to ensure factory acceptance rates.

2. Improve Installation and Sealing Standards

• Ensure sealing strips on access doors and inspection ports are fully compressed during installation to eliminate gaps.

• Use high-temperature and corrosion-resistant gaskets at flange connections.

• Ensure tight contact between the perforated plate and filter bag openings to prevent airflow short-circuiting.

3. Regular Maintenance and Replacement

• Periodically inspect sealing strips and gaskets for aging and replace promptly.

• Repair weld cracks and damaged hopper sections through welding or restoration.

• Maintain ash discharge valves regularly to preserve sealing effectiveness.

4. Install Air Leak Monitoring System

• Install negative pressure detection points at critical locations for real-time air leak monitoring.

• Install online flue gas concentration monitoring at the outlet to promptly detect anomalies.

5. Optimize Operational Management

• Maintain system negative pressure within reasonable limits to prevent exacerbated air leaks caused by excessive negative pressure.

• Conduct regular inspections of the housing and pipe connections, establishing a log of potential air leak hazards.

V. Case Analysis

During operation, a cement plant's pulse jet baghouse dust collector exhibited elevated outlet emission concentrations and high moisture content in the dust hopper. Investigation revealed:

• Aging seals on access doors allowed significant ingress of external cold air;

• Cracks in the weld seam connecting the inlet pipe to the housing.

Corrective actions taken:

1. Replaced the seal with high-temperature silicone rubber gaskets;

2. Rewelded the damaged weld seam;

3. Installed a dust concentration monitoring device at the outlet.

Following the modifications, the air leakage rate decreased from 15% to below 5%, and the emission concentration returned to compliance levels.

VI. Conclusion

Air leakage in dust collectors, though a hidden fault, poses significant hazards. It directly leads to reduced dust removal efficiency, filter bag damage, equipment corrosion, and increased energy consumption. Leaks primarily originate from welded seams in the housing, access doors, ash hoppers, duct connections, and improper filter bag sealing. To effectively address air leakage, adhere to the principle of “prevention first, timely detection, and thorough maintenance”:

• Ensure airtightness during design and manufacturing;

• Guarantee reliable sealing during installation;

• Identify issues promptly through multiple detection methods during operation;

• Perform timely repairs and replacements during maintenance.

Through systematic management, dust collector air leakage rates can be effectively controlled below 5%, ensuring safe, stable, and efficient equipment operation.