Polyester needle felt is a common industrial dust removal filter material, which is widely used in dust filtration systems of normal to medium temperature conditions such as cement, steel, grain processing, wood, and building materials. Although polyester needle felt has the advantages of high cost performance, stable structure, and good filtration performance, in the actual operation process, due to complex working conditions or improper maintenance, the filter bag may still have a variety of faults, affecting the dust removal efficiency and filter bag life. The following are several common faults of polyester needle felt during use and their cause analysis and countermeasures.
1. Filter bag damage
Phenomenon:
After a period of use, the filter bag has local holes, cracks or edge tears, resulting in dust penetration and excessive emissions.
Possible reasons:
The pulse cleaning pressure is too high or the frequency is too dense, causing fatigue fracture of the filter material.
The contact between the filter bag and the bag cage is worn, especially near the bag mouth, bottom or middle support ring.
High temperature operation exceeds the temperature resistance limit of polyester (>130℃), resulting in thermal aging and strength reduction.
Improper installation of the filter bag causes misalignment of the card slot or uneven force.
Countermeasures:
Reasonably adjust the cleaning parameters to avoid excessive impact.
Use a bag cage with qualified quality, smooth and burr-free.
Control the flue gas temperature within the allowable range of polyester (<120℃).
Ensure that it is installed in place and well sealed to avoid direct friction between the filter bag and metal parts.
2. Filter bag blockage (high resistance operation)
Phenomenon:
The resistance of the dust removal system continues to increase, the air volume decreases, and the pressure recovery after cleaning is not obvious.
Possible reasons:
The dust particle size is too fine and penetrates deep into the filter material to form "deep filtration".
The dust has high humidity and high viscosity, and it is easy to agglomerate or clump on the surface of the filter bag.
The surface of the filter bag has not been properly treated (such as coating, oil and water resistance, etc.).
The cleaning frequency or intensity is insufficient, and the dust layer cannot be effectively peeled off.
Countermeasures:
Use coated polyester filter bags or waterproof and oil-proof treatment to avoid sticking bags.
Adjust the cleaning system settings to improve the cleaning efficiency.
Add a pre-dust removal device to reduce the entry of large particles or high-humidity dust into the main filter bag area.
Perform regular online or offline maintenance to clean up the accumulated dust.
3. Filter bag sticking (sticking)
Phenomenon:
Moist and agglomerated dust adheres to the surface of the filter bag, which is difficult to remove, resulting in blockage of the air flow channel.
Possible causes:
The system inlet air temperature is close to or lower than the dew point, resulting in condensation.
The dust contains oil or corrosive gases, which combine with water vapor to produce acidic droplets.
The filter bag material has strong hygroscopicity and is not treated with moisture-proof.
Countermeasures:
Ensure that the flue gas temperature is more than 20°C higher than the dew point to avoid condensation.
Use polyester filter bags treated with waterproof and oil-proof treatment.
Keep the dust collector housing well sealed to prevent cold air from infiltrating and causing condensation.
Strengthen drainage and gas temperature monitoring.
4. Filter bag aging and embrittlement
Phenomenon:
The filter bag becomes hard, brittle, and easy to break, and its service life is significantly shortened.
Possible causes:
Operating in a high-temperature environment for a long time, thermal aging.
Contact with acidic and alkaline gases or water vapor, chemical hydrolysis reaction occurs.
Improper selection of filter bags, used in high temperature or corrosive gas occasions.
Countermeasures:
Avoid high temperature operation exceeding the temperature resistance limit of polyester.
Deacidify or cool and dehumidify the flue gas.
If the working conditions are harsh, you can use filter materials that are more resistant to chemical corrosion (such as PPS, PTFE, etc.).
V. Filter bags fall off and are not installed firmly
Phenomenon:
The filter bag loosens or slips from the hole of the flower plate during operation, causing short-circuit emission of dust.
Possible reasons:
The filter bag size does not match the flower plate hole well, and the sealing ring is too loose.
The installation is not tight or the sealing clamp fails.
The filter bag is displaced or damaged due to vibration, impact.
Countermeasures:
Select the filter bag size and clamp ring strictly according to the equipment requirements.
During installation, make sure that each filter bag is firmly fixed and tightly sealed.
Regularly check the contact between the bag mouth and the flower plate, and replace it in time if it is loose.
6. Deformation or drooping of filter bags
Phenomenon:
The shape of the filter bags is twisted, bent, and drooping, affecting the airflow distribution and dust cleaning effect.
Possible reasons:
After long-term operation, the filter bags lose elastic support and structural fatigue.
High temperature or chemical reaction leads to strength loss and material softening.
The bag cage support fails or deforms, and the filter bag shape cannot be maintained.
Countermeasures:
Use qualified steel bag cages to ensure sufficient vertical support.
Check the status of the filter bags and bag cages regularly, and replace them in time if abnormalities are found.
If the operating temperature is high, high-temperature filter materials such as aramid or PPS should be used.
Conclusion
Although polyester needle felt has good comprehensive performance as a normal temperature dust removal filter material, it still has a certain risk of failure in actual application. The failure of filter bags is often the result of multiple factors, which is closely related to equipment operating conditions, filter bag selection, installation quality and maintenance management.
In order to reduce the occurrence of failures and extend the life of filter bags, users should select reasonable models according to working conditions, strengthen operation monitoring and daily maintenance, and regularly check the status of filter bags to achieve early detection and early treatment to ensure the long-term, safe and stable operation of the dust removal system.