Common Causes of PTFE Needle Punched Felt Filter Bag Damage and Preventative Measures

1. Common Causes of PTFE Needle Punched Felt Filter Bag Damage

Mechanical Damage

• Cause Analysis

Improper installation: Misalignment of the filter bag and cage frame, resulting in friction or compression.

Design flaws in the cleaning system: Excessive pulse jet pressure (>0.5 MPa) or misalignment of the jet pipe, causing partial tearing of the filter bag.

Uneven slats: Burrs on the edges of the slat holes can scratch the filter bag.

• Preventative Measures

Pre-installation inspection: Ensure the cage frame is smooth and burr-free, and that the filter bag is suspended vertically.

Optimize cleaning parameters: Control pulse pressure (0.2-0.4 MPa) and jet distance (≤200 mm from the bag opening).

Use laser alignment: Adjust the concentricity of the slat holes and the jet pipe (tolerance <2 mm).

Chemical Corrosion

• Cause Analysis

Acidic gases (SO₂, HCl): In high-temperature, high-humidity environments, they generate corrosive liquids, destroying the PTFE fiber structure.

Alkaline dust (cement kiln dust): Reacts with PTFE, causing the filter bags to become brittle.

• Preventive Measures

Select coated filter bags: The PTFE coating prevents chemical penetration.

Control the flue gas dew point: Maintain the chamber temperature at least 10°C above the dew point to prevent condensation.

Pre-coat the filter bags with a protective layer: Pre-coat the filter bags with lime powder or talcum powder before commissioning to neutralize acidic substances.

High-Temperature Burn-Through

• Cause Analysis

Transient overheating: Flue gas temperatures exceeding 260°C (PTFE's tolerance limit) cause the filter bags to shrink or melt.

Sparks: Failure to install a spark arrestor allows high-temperature particles to burn the filter bags.

• Preventive Measures

Install a cold air valve: A temperature sensor activates the cold air system to automatically reduce the temperature. Pre-spark arrester: Intercepts high-temperature particles in the flue gas.

Select a high-temperature-resistant base material, such as a PPS+PTFE composite filter bag (temperature resistant up to 190°C).

Excessive Filtration Air Velocity

• Cause Analysis

Exceeding the Design Air Velocity: When air velocity exceeds 1.2 m/min, the dust layer is penetrated, increasing filter bag wear.

Uneven Airflow Distribution: Locally excessive air velocity causes frequent vibration and rupture of the filter bags.

• Preventive Measures

Rational Design Air Velocity: Under normal operating conditions, control it between 0.8 and 1.0 m/min.

Add an Airflow Distributor: Optimize airflow distribution within the filter housing and reduce eddy currents.

Dust Cleaning Failure

• Cause Analysis

Pulse valve failure: Diaphragm damage or solenoid coil failure, resulting in insufficient dust cleaning.

Compressed air contains moisture: Moisture combines with dust to form a paste in the bag, increasing operating resistance.

• Preventive Measures

Regularly maintain the air path: Check the pulse valve for leaks and drain any accumulated water from the air storage tank. Use dry compressed air: install a refrigerated dryer, the dew point temperature is ≤-20℃.

2. Correct Use and Operating Instructions for PTFE Needle Punched Felt Filter Bags

Pre-Installation Preparations

Inspect the Filter Bag and Supporting Components

Filter Bag Inspection:

Confirm that the specifications (diameter, length, and weight) are consistent with the design requirements.

Inspect the surface for damage, pinholes, or poor seams.

Ensure the integrity of the PTFE membrane (for membrane-coated filter bags).

Supporting Component Inspection:

Cage Frame: No deformation or burrs, smooth surface (silicon coating recommended).

Front Plate: Hole edges are flat and burr-free, and the pore size matches the filter bag (tolerance ≤ ±1mm).

Sealing Gasket: Made of high-temperature-resistant material (such as silicone rubber), free of aging cracks.

Pre-Spray Protection (Applicable to New Filter Bags)

Purpose: Prevent dust from embedding directly into the filter fibers during initial operation, causing clogging.

Method:

Evenly spray lime powder or talcum powder (particle size ≤ 20μm) on the filter bag surface. After spraying, run the filter bag at no load for 10-15 minutes to allow the powder to adhere evenly.

Filter Bag Installation Steps

Installation Sequence

First, install the cage frame: Insert the cage frame vertically into the perforation of the panel, ensuring that the bottom is flush with the panel.

Next, install the filter bag:

With both hands, gently press the top of the filter bag and slowly insert it into the cage frame, avoiding twisting or pulling.

Ensure a 1-2mm gap between the filter bag and the cage frame (overtightening may cause wear).

Secure the seal: Use a spring ring or clamp to tighten the bag opening to ensure no leaks.

Installation Precautions

Do Not:

Drag the filter bag directly to avoid scratching the PTFE fibers.

Use a sharp tool (such as a screwdriver) to assist in installation.

Recommendation:

Wear clean gloves during installation to avoid contamination of the filter bag with oil.

After installation, gently pat the filter bag to check that it is straight and wrinkle-free.