The cleaning method of bag filter is the core technology that determines its dust removal efficiency, filter bag service life, and operational stability. The core logic is to peel off the dust layer attached to the surface of the filter bag through mechanical force, air flow back blowing, or pulse spraying (to avoid filter bag blockage and high resistance). According to structural design, cleaning strength, and applicable scenarios, mainstream cleaning methods can be divided into three categories, with specific characteristics, applicable scenarios, and technical details as follows:

1、 Pulse jet cleaning (currently mainstream in industry, widely used)

1. Working principle

The high-speed airflow generated by the instantaneous blowing of compressed air drives the filter bag to rapidly expand and vibrate, while forming a reverse airflow to forcibly peel off the dust layer on the outer surface of the filter bag.

Core components: air bag (storing compressed air), pulse valve (controlling airflow injection), spray pipe (with nozzle, aligned with filter bag mouth), PLC controller (pressing difference or time triggered dust cleaning);

Spray process: The controller sends a signal → the pulse valve opens instantly → compressed air (pressure 0.4-0.6MPa) is sprayed from the air bag through the spray pipe nozzle at supersonic speed (about 300m/s) into the interior of the filter bag → the filter bag suddenly expands and vibrates, causing the dust layer to break and fall off → the dust falls into the ash hopper.

2. Key classification (by whether to stop filtering during dust cleaning)

Online pulse dust cleaning: During dust cleaning, the filter bag does not stop filtering, and the airflow passes through normally. It is suitable for handling scenarios with continuous airflow and high requirements for operational stability (such as dust removal from power boiler flue gas);

Offline pulse dust cleaning: The dust collector is divided into multiple filter bag chambers, and the air inlet/outlet of one chamber is closed during dust cleaning (the filtration in that chamber is temporarily suspended), which ensures more thorough dust cleaning and avoids secondary adsorption of dust. It is suitable for high concentration and fine particle dust (such as dust removal in cement mills and metallurgical sintering machines).

3. Advantages

High dust cleaning efficiency: With strong instantaneous blowing force, it can completely peel off viscous dust and fine particle dust, and the filtering resistance is stable (the resistance can be reduced to 800-1000Pa after dust cleaning);

Small damage to the filter bag: short spraying time (0.1-0.3 seconds/time), moderate vibration amplitude of the filter bag, and long service life (1-3 years under normal working conditions);

High degree of automation: can be controlled by pressure difference (1200-1500Pa trigger) or time (10-30 minutes/time) without manual intervention;

Wide adaptability: can handle low concentration (10mg/m ³) to high concentration (1000g/m ³) dust, compatible with dry and slightly viscous dust.

4. Disadvantages

Compressed air system needs to be configured: additional air compressors and dryers are required (to avoid condensation of filter bags caused by compressed air carrying water), increasing initial investment and operating costs;

The structure is relatively complex: components such as pulse valves and spray pipes require regular maintenance (such as replacement of pulse valve membranes, with a lifespan of about 1-2 years).

5. Typical application scenarios

The vast majority of industrial scenarios include cement kiln tail/kiln head, steel blast furnace/converter, electric boiler, chemical catalyst recovery, powder coating workshop, grain processing, etc.

2、 Anti blowing dust cleaning (traditional classic type, suitable for medium and low concentration dust)

1. Working principle

By blowing the dust with reverse airflow and utilizing the difference in airflow velocity and pressure, the dust layer can detach from the surface of the filter bag without the need for mechanical vibration.

Core components: anti hair dryer (providing reverse airflow), switching valve (controlling forward/reverse airflow), deflector (evenly distributing reverse airflow);

Dust cleaning process: When the filtration resistance reaches the set value, the switching valve closes the inlet air and turns on the reverse blower. The reverse airflow (wind speed 0.5-1.0m/min) blows from the clean side (inner side) of the filter bag to the dusty side. The dust layer is blown loose and falls off. The switching valve is reset to restore normal filtration.

2. Key classification (by airflow direction and structure)

Positive pressure reverse blowing dust cleaning: The dust collector operates under positive pressure, and the reverse blowing machine provides negative pressure reverse airflow, suitable for small equipment (such as single machine dust collectors);

Negative pressure back blowing dust removal: The dust collector operates under negative pressure, and the back blowing machine provides positive pressure and reverse airflow, suitable for large multi chamber dust collectors (such as material crushing dust removal in the building materials industry);

Rotary reverse blowing dust cleaning: By rotating the rotary spray pipe, each row of filter bags is sequentially blown back. The structure is compact and suitable for high air volume scenarios (such as dust removal from waste incineration and power generation flue gas).

3. Advantages

Low energy consumption: No need for compressed air, low power of the anti blow dryer (only 1/3-1/2 of pulse blowing), and low long-term operating costs;

Simple structure: no vulnerable parts such as pulse valves and spray pipes, low maintenance workload, and low failure rate;

Minimal damage to filter bags: relying solely on airflow to loosen, without vibration or impact, the filter bag has a long lifespan (up to 3-5 years) and is suitable for fragile filter bags (such as fiberglass filter bags).

4. Disadvantages

Weak dust cleaning force: can only blow loose dry, non sticky fine particle dust, incomplete cleaning of sticky dust and coarse particle dust can easily lead to increased resistance;

Low filtration wind speed: To avoid reverse airflow penetrating the filter bag, the filtration wind speed needs to be controlled at 0.5-0.8m/min. The equipment has a large volume and occupies a wide area;

Not suitable for high concentration dust: When the inlet dust concentration exceeds 50g/m ³, a cyclone dust collector should be used for pre dust removal, otherwise the cleaning frequency will be too high.

5. Typical application scenarios

Dry and low viscosity dust scenarios such as grain processing (flour, corn flour), wood processing (wood flour), power industry waste heat boiler, low concentration chemical tail gas purification, etc.

3、 Mechanical vibration cleaning (traditional simple type, suitable for small equipment)

1. Working principle

By using mechanical force (tapping, vibration) to generate high-frequency vibration in the filter bag, and utilizing inertia to shake off the dust layer from the surface of the filter bag.

Core components: vibration motor (providing power), eccentric wheel/cam (converting rotational motion into vibration), vibration rod/frame (connecting filter bags and transmitting vibration);

Dust cleaning process: The motor drives the eccentric wheel to rotate → The vibration rod/frame vibrates up and down/left and right (frequency 50-100Hz) → The filter bag follows the vibration, and the dust layer falls off due to inertia → The dust falls into the ash hopper.

2. Key classification (by vibration position)

Top vibration cleaning: The vibration device is located at the top of the filter bag and drives all filter bags to vibrate synchronously through a frame. The structure is simple (such as a simplified version of a single pulse dust collector);

Middle vibration cleaning: The vibration device is located in the middle of the filter bag, with more concentrated vibration and slightly better cleaning effect than top vibration, but it causes greater damage to the filter bag;

Bottom vibration cleaning: The vibration device is located at the bottom of the filter bag and is suitable for long filter bags (length>3m), but the vibration transmission efficiency is low and its application is limited.

3. Advantages

The structure is extremely simple: there is no compressed air system, reverse blower, and low initial investment (only 1/2-1/3 of pulse blowing);

Extremely low maintenance cost: The only vulnerable parts are the vibration motor bearings and eccentric wheels, which are easy to replace and do not require professional skills;

Easy to operate: can be manually triggered or timed controlled, suitable for small workshops and single machine dust removal (such as welding fumes, small polishing equipment).

4. Disadvantages

Poor dust cleaning effect: The mechanical vibration force is dispersed and can only handle coarse particles (>10 μ m) and dry non sticky dust. The dust cleaning for fine particles and slightly sticky dust is not thorough, and the resistance is prone to increase;

Heavy damage to filter bags: Long term high-frequency vibration can cause breakage at the seam of the filter bag, fiber fatigue aging, and a short service life (only 6-12 months);

Not suitable for high air volume and high concentration scenarios: dust is prone to secondary flying during vibration, and offline dust cleaning cannot be achieved. The processing air volume is usually less than 10000m ³/h.

5. Typical application scenarios

Small mechanical processing (such as machine tool grinding, welding dust), mining small crushing equipment, laboratory dust treatment, agricultural machinery processing (such as feed crusher dust removal) and other low air volume, low concentration, coarse particle dust scenarios.

4、 Other special dust cleaning methods (for niche applications)

1. Composite dust cleaning (mechanical vibration+reverse blowing/pulse spraying)

Principle: Combining the advantages of two cleaning methods (such as mechanical vibration loosening powder+anti blowing powder removal) to improve the cleaning effect;

Applicable scenarios: high concentration, medium viscosity dust (such as coal powder preparation systems, chemical raw material crushing).

2. Acoustic cleaning (auxiliary cleaning method)

Principle: High frequency sound waves (100-1000Hz) are generated by a sound wave generator, and the vibration of the sound waves is used to loosen the dust layer, usually as an auxiliary means of pulse blowing;

Applicable scenarios: long filter bag length (>6m), fine particle dust (such as catalyst dust), to avoid dust accumulation at the bottom of the filter bag.