Applications of pulse jet dust collectors in the power and boiler industries

I. Industry Background and Dust Characteristics

The power and boiler industry is one of the largest coal-consuming industrial sectors. The flue gas produced during coal combustion contains large amounts of pollutants such as dust, sulfur dioxide, and nitrogen oxides. Especially in coal-fired boilers, circulating fluidized bed boilers, and biomass boilers, the dust concentration in the flue gas can reach 20–80 g/Nm³, with small particle size, high activity, and often accompanied by high temperature, high humidity, and corrosive gases.

The main task of power plant dust removal systems is to effectively capture fly ash under high temperature and high flow rate conditions, ensuring that the emission concentration meets the national "Emission Standard for Air Pollutants for Boilers." While traditional electrostatic precipitators (ESPs) were widely used in the early days, their efficiency drops significantly under low-sulfur coal, biomass fuel, and variable load operating conditions. Therefore, high-efficiency pulse jet bag filters have gradually become the main equipment for boiler flue gas treatment.

II. Challenges in Dust Removal from Power Boilers

High and Fluctuating Flue Gas Temperature:

The flue gas temperature of coal-fired boilers is generally 130–200℃, but can reach as high as 250℃ during start-up or shutdown. Excessively high temperatures can erode filter bags, while excessively low temperatures can cause condensation and clogging.

Fine and Charged Dust Particles:

Fly ash particles have an average diameter of 1–10 μm, some of which are hygroscopic and sticky, easily forming a dense dust layer on the filter bag surface, increasing resistance.

Contains Corrosive Gases:

SO₂ in the flue gas combines with water vapor to form sulfuric acid mist, which corrodes both the dust collector shell and the filter bags.

Frequent Operating Fluctuations:

Frequent boiler start-ups and shutdowns, along with load fluctuations, lead to drastic changes in flue gas volume, temperature, and dust concentration, requiring the dust collector to possess excellent self-adaptive and stable performance.

III. Advantages of Pulse Jet Dust Collectors in the Power Industry

1. Highly Efficient and Stable Dust Removal Performance

Pulse jet baghouse dust collectors utilize high-pressure pulse-jet cleaning, achieving a filtration efficiency of over 99.9%. Outlet emission concentrations can be controlled below 20 mg/Nm³, far superior to traditional electrostatic precipitators.

2. Strong Adaptability to Coal Type and Load Changes

Baghouse dust collectors are mechanical filtration systems, unaffected by dust resistivity or coal quality changes. They maintain stable performance even under low load and low-sulfur coal conditions.

3. Small Footprint and Flexible System

Pulse jet dust collectors can be flexibly combined according to boiler capacity, featuring a compact structure and convenient installation, suitable for both new construction and renovation projects.

4. Synergistic Integration with Desulfurization and Denitrification Systems

Dust removal systems can be arranged before and after the desulfurization tower, achieving integrated "dust removal + desulfurization + denitrification" as needed, facilitating ultra-low emission retrofitting.

IV. Structural Design and Technical Points

(1) System Layout

Power plants typically use a flue gas flow path of boiler—economizer—air preheater—bag filter—induced draft fan—chimney.

The dust collector should be equipped with a bypass flue to protect the filter bags in case of abnormal boiler temperature rise.

(2) Filter Bag Material

Select different filter materials according to flue gas characteristics:

Operating Condition | Recommended Filter Material | Characteristics

Ordinary Coal-fired Boiler | PPS needle-punched felt | Temperature resistance 190℃, good acid and alkali resistance

High-Temperature Boiler (CFB) | P84 / Fiberglass Composite Felt | Temperature resistance 260℃, excellent dimensional stability

Biomass Boiler | PTFE membrane filter material | Anti-condensation, corrosion resistance, strong anti-clogging ability

Filter bags are generally 6-8m long, 130-160mm in diameter, and have a service life of 2-4 years.

(3) Dust Removal System

An offline pulse dust removal design is adopted, cleaning only one compartment at a time while other compartments continue filtration. This avoids secondary dust re-entrainment and maintains stable operation. The pulse pressure is controlled between 0.5 and 0.7 MPa, and the dust removal cycle is automatically adjusted by the pressure difference.

(4) Airflow Distribution and Anti-Condensation

The air inlet should be equipped with a flow guide device to prevent high-speed flue gas from directly impacting the bottom of the filter bag; at the same time, an insulation layer and an electric heating device are required to prevent condensation and bag clogging in the low-temperature section.

V. Practical Application Cases

Case 1: Dust Removal System for a 300MW Coal-fired Power Plant Boiler

The plant originally used a three-field electrostatic precipitator, with an emission concentration of 65mg/Nm³, which was insufficient to meet the new emission standards. After the upgrade, 8 sets of air-box pulse dust collectors were used, with a filtration area of 11,000m², employing PPS membrane filter bags.

Results:

Outlet emission concentration remained stable at ≤ 15mg/Nm³;

Differential pressure was controlled between 1100~1300Pa;

Filter bag lifespan exceeded 3 years;

The system could operate stably at 60% load.

Case 2: Dust Removal Project for a Biomass Boiler

This project involved high humidity and high tar content in the flue gas. The design adopted PTFE fully membrane filter bags and a double-layer insulation structure. After one year of operation, the differential pressure fluctuation was small, no bag clogging occurred, and the dust removal efficiency reached 99.95%.

VI. Operation and Maintenance Points

Control inlet temperature: Maintain within the filter media's temperature resistance range, typically 150–180℃;

Maintain dry airflow: Avoid condensation; use hot air tracing or electric heating if necessary;

Regularly monitor differential pressure: Automatically clean ash when resistance exceeds the set upper limit (e.g., 1500Pa);

Prevent ash accumulation in the ash hopper: Install a rotary valve and level gauge to ensure continuous ash discharge;

Regularly check pulse valves and air tanks: Prevent uneven blowing that leads to dead zones in ash cleaning;

Filter bag maintenance: Inspect wear every six months and replace aging filter bags promptly.

VII. Application Effects and Environmental Significance

The promotion of pulse jet baghouse dust collectors in the power and boiler industries benefits enterprises in both economic and environmental aspects:

Achieving Standard Emissions: Meets ultra-low emission requirements (≤20mg/Nm³);

Energy Saving and Consumption Reduction: Stable system resistance reduces fan energy consumption by approximately 10%;

Improving Boiler Thermal Efficiency: Effectively recovers fly ash and reduces pipe blockage;

Extending Equipment Lifespan: Corrosion-resistant and anti-condensation design reduces maintenance frequency;

Enhancing Corporate Image: Achieving clean production and green power plant construction goals.

VIII. Conclusion

The power industry's flue gas treatment has entered the era of "ultra-low emissions." Pulse jet baghouse dust collectors, with their high efficiency, strong adaptability, and low operating costs, have gradually replaced traditional electrostatic precipitators, becoming the mainstream equipment for boiler flue gas dust removal.

In the future, with the development of intelligent control and new filter media technologies, baghouse dust collection systems will achieve more efficient, energy-saving, and intelligent upgrades, providing strong technical support for the green transformation of the power industry.