Fabric dust collectors are commonly known as bagfilters and Baghouses are the most efficient and cost effective dust collector models. Dust enters the fabric filter compartment. Larger particles drop out while smaller dust particles collect on filter Bags.
Fabric dust collectors are commonly known as bagfilters and Baghouses are the most efficient and cost effective dust collector models. Dust enters the fabric filter compartment. Larger particles drop out while smaller dust particles collect on filter Bags. When the dust layer thickness reaches a level where flow through the system is restricted (called pressure drop or delta P), the bag cleaning process is initiated. Cleaning can be done while the compartment is still online (filtering) or in isolation (offline). Once cleaned, the compartment is placed back in service and the filtering process starts over. There are three prominent types of cleaning process in bagfilters and baghouses: Reverse Air (Gas Cleaning), Pulse Air (Compressed Air Cleaning) and Shaker (Mechanical Cleaning). Bags are made of different material such as woven or felted cotton, synthetic, or glass-fiber.
Important considerations while selecting fabric filter material for bagfilter and baghouse collectors:
Temperature of incoming dusty air stream
Moisture levels in the collector and hydroscopic nature of dusts
Electrostatic nature of dust particles
Abrasion levels caused by dust particles
Acid chemical resistance and Alkali chemical resistance of fabric
Fabric’s capability to release dust cake easily
Fabric’s permeability to allow air to pass
Size of dust particles
Fabric filters are designed by considering a number of variables beside inlet gas specification: pressure drop, Air-to-cloth ratio, can velocity.
Pressure drop (Δp), a very important fabric filter design variable, describes the resistance to air flow across the bagfilter and baghouse: the higher the pressure drop, the higher the resistance to air flow.
Pressure drop is usually expressed in milibar, millimeters of mercury or millimeters of water. The pressure drop of a system (fabric filter) is determined by measuring the difference in total pressure at two points, usually the inlet and outlet.
Filtration Velocity: Air-To-Cloth Ratio
The terms filtration velocity and air-to-cloth (A/C) ratio can be used interchangeably. The air-to-cloth ratio (also called the gas-to-cloth ratio) is defined as the ratio of gas filtered in cubic meter per minute (cm/m) to the area of filtering media in square meter. Typical units used to express the A/C ratio are: (cm3/sec)/cm2 or (ft3/min)/ft2
A high air-to-cloth ratio means a large volume of air passes through the fabric area. A low air-to-cloth ratio means a small volume of air passes through the fabric.
Can velocity is the velocity of the gas in the passages between the filter units in the filter house of a gas filter. This velocity is defined in meter per minute. Other typical units used to express are: ft/min or cm/sec
For units that use on-line cleaning, the dust released during cleaning must fall through filter area as it settles by gravity. If the upward velocity of the inlet gas stream exceeds the downward terminal settling velocity, the particle will be caught and return to the bag-dust cake surface.
The primary function of a cyclone is to separate dust from a gas stream. After separation, the dust discharges out the bottom of the cyclone and air discharges through the top exhaust. Cyclones (or centrifugal collectors) create a ‘cyclonic’ or centrifugal force, similar to water going down a drain, to separate dust from the polluted air stream.
A group of engineers with years of experiences established Fanavaran ShayanTarh Company to improve environmental conditions in different industries since 2007. We are a leading provider in filtration and dedusting air pollution industry.