Troubleshooting of Bag Filter | Maintenance aspect of Bag Filter/Bag House

Troubleshooting of Bag Filter | Maintenance aspect of Bag Filter
While selecting the filter medium the characteristics and following properties of the carrier gas and dust particles should be considered.
1. Operating temperatures and Gas flow rate.
2. Humidity and moisture levels
3. Type and size of particulate being handled and its concentration
4. Resistance to abrasion, chemicals, moisture, etc.
5. Filter Air-to-Cloth Ratio
General application (Dry Gas) up to 120 °C (Long time operation), needle felt fabric made from high quality Polyester fibers are used. Example: Limestone, Gypsum, Clinker, etc application Nuisance Bag Filter
Application in Drying/Grinding (Humid Gas) up to 120 °C (long time operation), PolyAcrylNitrile or similar fiber cloth is recommended. Example: Coal Mill Bag House, etc application Bag Filter (The fabric shall be flame signed calendared with PTFE impregnation for water and oil repellence. Antistatic flame retardant finish for coal application.)
The high efficiency of dust collectors is due to the dust cake formed on the surfaces of the bags.
The fabric primarily provides a surface on which dust particulates collect through the following four mechanisms:
1. Inertial Collection - Dust particles strike the fibers placed perpendicular to the gas-flow direction instead of changing direction with the gas stream.
2. Interception - Particles that do not cross the fluid streamlines come in contact with fibers because of the fiber size.
3. Brownian Movement - Submicron particles are diffused, increasing the probability of contact between the particles and collecting surfaces.
4. Electrostatic Forces - The presence of an electrostatic charge on the particles and the filter can increase dust capture.
A combination of these mechanisms results in formation of the dust cake on the filter, which eventually increases the resistance to gas flow.
The filter must be cleaned periodically.
Application for temperatures up to 250 °C (long time operation), PolyTetraFluorEthylene (PTFE) is recommended. Example: Reverse Air Bag House.
What is air to cloth ratio of Bag filter? What is Air Permeability of Filter cloth of Dust collector?
Air to cloth ratio is the ratio Volumetric flow rate of air vs total cloth area.
Filtration velocity is actually the velocity at which the dust laden gases travel across the filter element. Unit is M³ / M² / Minute or M / Min (Filtration velocity)
The Air-to-Cloth Ratio is typically between 1.0 and 3.5 Metres per minute, mainly depending on the concentration of dust loading.
The more critical the dust { fine, light, sticky, non-agglomerating, abrasive, etc} or higher the dust loading, the larger is the filtration area provided, i.e. lower is the air-to-cloth ratio maintained.
The air permeability of a fabric is a measure of how well it allows the passage of air through it. Value range is 16-20 M³/Min/M² @20 mmwc
Type of dust separation;
1. Intermittent Shaking (Cleaning by Vibratory motor)
2. Shaking & Reverse Air (Cleaning by Low pressure reverse air)
3. Low Pressure Cleaning (Air Purse Pressure 3-4 Kg/mm2)
4. Pulse Jet Cleaning (Air Purse Pressure 4-6 Kg/mm2)
Process Bag Filter | Bag House construction feature | Pollution Control equipment | installation guideline for process Bag filter
Type of Pollution Control equipment’s
Type of Bag Filter
Online Bag filter working Principle
Type of Filter Bag Fixing arrangement
What is Pollution Control Equipment
In industrial process, various particulate and gaseous matter get generated are called as pollutant.
Those pollutant are allowed to pass through an equipment which separates particulate matter (like fly ash, lime stone, coal dust, cement etc.) and gaseous matter (like Sox, Nox, volatile organic etc) from air stream.
Clean air then let out to atmosphere and thus controlling pollution in atmosphere.
Bag filter working Principle
The dust laden air enters through the hopper by suction or positive pressure. The heavier dust particles fall immediately into the hopper, while the lighter dust gets deposited on the outside of the filter bags. This dust is removed in a pre-determined cycle by pulse of high pressure compressed air.
Constructional features of Bags Fixing
a.Coller Bend Type
b. Snap bend type
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