Chasm offered Systems can be Used at
- Dust collectors are used in many processes to either recover valuable granular solid or powder from process streams, or to remove granular solid pollutants from exhaust gases prior to venting to the atmosphere. Dust collection is an online process for collecting any process-generated dust from the source point on a continuous basis. Dust collectors may be of single unit construction, or a collection of devices used to separate particulate matter from the process air. They are often used as an air pollution control device to maintain or improve air quality.
- Mist collectors remove particulate matter in the form of fine liquid droplets from the air. They are often used for the collection of metal working fluids, and coolant or oil mists. Mist collectors are often used to improve or maintain the quality of air in the workplace environment.
- Fume and smoke collectors are used to remove sub micrometer size particulate from the air. They effectively reduce or eliminate particulate matter and gas streams from many industrial processes such as welding, rubber and plastic processing, high speed machining with coolants, tempering, and quenching.
Dust collectors can be configured into one of five common types.
Ambient units are free-hanging systems for use when applications limit the use of source-capture arms or ductwork.
Collector booths require no ductwork, and allow the worker greater freedom of movement. They are often portable.
A downdraft table is a self-contained portable filtration system that removes harmful particulates and returns filtered air back into the facility with no external ventilation required.
Source collector or Portable units
Portable units are for collecting dust, mist, fumes, or smoke at the source.
An example of a stationary collector is a bag house.
An effective dust collection system offered to enhance the quality of air released from industrial and commercial processes by collecting dust and other impurities from air or gas. Designed to handle high-volume dust loads, a dust collector system consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system. It is distinguished from air cleaners, which use disposable filters to remove dust.
Commonly known as bag houses, fabric collectors use filtration to separate dust particulates from dusty gases. They are one of the most efficient and cost effective types of dust collectors available and can achieve a collection efficiency of more than 99% for very fine particulates. Dust-laden gases enter the bag house and pass through fabric bags that act as filters. The bags can be of woven or felted cotton, synthetic, or glass-fiber material in either a tube or envelope shape. Bag houses are characterized by their cleaning method.
- Manual or Motorized Shaking – A rod connects to the bag is powered by a motor that provides motion to remove the caked on particles. The speed and motion of the shaking depends on the design of the bag and composition of the particulate matter. Though, generally shaking is horizontal. The top of the bag is closed and the bottom is open. When shaken the dust collected on the inside of the bag is set free. During the cleaning process, no dirty gas flows through a bag while the bag is being cleaned. This redirection of air flow illustrates why bag houses must be compartmentalized.
- Reverse Air – Air flow gives the bag structure. Dirty air flows through the bag from the inside, allowing dust to collect on the interior surface. During cleaning, gas flow is restricted from a specific compartment. Without the flowing air, the bags relax. The cylindrical bag contains rings that prevent it from completely collapsing under the pressure of the air. A fan blows clean air in the reverse direction. The relaxation and reverse air flow cause the dust cake to crumble and release into the hopper. Upon the completion of the cleaning process, dirty air flow continues and the bag regains its shape.
- Pulse Jet – This type of bag house cleaning (also known as pressure-jet cleaning) is the most common. A high pressure blast of air is used to remove dust from the bag. The blast enters the top of the bag tube, temporarily ceasing the flow of dirty air. The shock of air causes a wave of expansion to travel down the fabric. The flexing of the bag shatters and discharges the dust cake. The air burst is about 0.1 second and it takes about 0.5 seconds for the shock wave to travel down the length of the bag. Due to its rapid release, the blast of air does not interfere with contaminated gas flow. Therefore, pulse-jet bag houses can operate continuously and are not usually compartmentalized. The blast of compressed air must be powerful enough to ensure that the shock wave will travel the entire length of the bag and fracture the dust cake.
- Sonic – The least common type of cleaning method is sonic. Shaking is achieved by sonic vibration. A sound generator produces a low frequency sound that causes the bags to vibrate. Sonic cleaning is commonly combined with another method of cleaning to ensure thorough cleaning.
Cartridge collectors use perforated metal cartridges that contain a pleated, nonwoven filtering media, as opposed to woven or felt bags used in bag houses. The pleated design allows for a greater total filtering surface area than in a conventional bag of the same diameter, the greater filtering area results in a reduced air to media ratio, pressure drop, and overall collector size.
Cartridge collectors are available in single use or continuous duty designs. In single-use collectors, the dirty cartridges are changed and collected dirt is removed while the collector is off. In the continuous duty design, the cartridges are cleaned by the conventional pulse-jet cleaning system.
A cyclone separator is an apparatus for the separation, by centrifugal means, of fine particles suspended in air or gas. Commonly known as bag houses, fabric collectors use filtration to separate dust particulates from dusty gases. They are one of the most efficient and cost effective types of dust collectors available and can achieve a collection efficiency of more than 99% for very fine particulates.
A high speed rotating (air) flow is established within a cylindrical or conical container called a cyclone. Air flows in a helical pattern, beginning at the top (wide end) of the cyclone and ending at the bottom (narrow) end before exiting the cyclone in a straight stream through the center of the cyclone and out the top. Larger (denser) particles in the rotating stream have too much inertia to follow the tight curve of the stream, and strike the outside wall, then falling to the bottom of the cyclone where they can be removed. In a conical system, as the rotating flow moves towards the narrow end of the cyclone, the rotational radius of the stream is reduced, thus separating smaller and smaller particles. The cyclone geometry, together with flow rate, defines the cut point of the cyclone. This is the size of particle that will be removed from the stream with 50% efficiency. Particles larger than the cut point will be removed with a greater efficiency and smaller particles with a lower efficiency.
An impinger system is a device in which particles are removed by impacting the aerosol particles into a liquid. Modular media type units combine a variety of specific filter modules in one unit. These systems can provide solutions to many air contaminant problems. A typical system incorporates a series of disposable or cleanable pre-filters, a disposable vee-bag or cartridge filter. HEPA or carbon final filter modules can also be added. Various models are available, including free-hanging or ducted installations, vertical or horizontal mounting, and fixed or portable configurations. Filter cartridges are made out of a variety of synthetic fibers and are capable of collecting sub-micrometer particles without creating an excessive pressure drop in the system. Filter cartridges require periodic cleaning.
A wet scrubber, or venturi scrubber, is similar to a cyclone but it has an orifice unit that sprays water into the vortex in the cyclone section, collecting all of the dust in a slurry system. The water media can be re circulated and reused to continue to filter the air. Eventually the solids must be removed from the water stream and disposed of.
These Dust collectors that use liquid are known as wet scrubbers. In these systems, the scrubbing liquid (usually water) comes into contact with a gas stream containing dust particles. Greater contact of the gas and liquid streams yields higher dust removal efficiency.
There is a large variety of wet scrubbers; however, all have one of three basic configurations:
Gas-humidification – The gas-humidification process agglomerates fine particles, increasing the bulk, making collection easier.
Gas-liquid contact – This is one of the most important factors affecting collection efficiency. The particle and droplet come into contact by four primary mechanisms :
Inertial impaction – When water droplets placed in the path of a dust-laden gas stream, the stream separates and flows around them. Due to inertia, the larger dust particles will continue on in a straight path, hit the droplets, and become encapsulated.
Interception – Finer particles moving within a gas stream do not hit droplets directly but brush against and adhere to them.
Diffusion – When liquid droplets are scattered among dust particles, the particles are deposited on the droplet surfaces by Brownian movement, or diffusion. This is the principal mechanism in the collection of sub micrometre dust particles.
Condensation nucleation – If a gas passing through a scrubber is cooled below the dew point, condensation of moisture occurs on the dust particles. This increase in particle size makes collection easier.
Gas-liquid separation – Regardless of the contact mechanism used, as much liquid and dust as possible must be removed. Once contact is made, dust particulates and water droplets combine to form agglomerates. As the agglomerates grow larger, they settle into a collector.
Types of Wet Scrubbers
Low-energy scrubbers (0.5 to 2.5 inches water gauge – 124.4 to 621.9 Pa)
- Low- to medium-energy scrubbers (2.5 to 6 inches water gauge – 0.622 to 1.493 kPa)
- Medium- to high-energy scrubbers (6 to 15 inches water gauge – 1.493 to 3.731 kPa)
- High-energy scrubbers (greater than 15 inches water gauge – greater than 3.731 kPa)
Due to the large number of commercial scrubbers available, it is not possible to describe each individual type here. However, the following sections provide examples of typical scrubbers in each category.
Low Energy Scrubbers
Welding fume extraction system
The welding process is being hazardous at the process of melting of two metallic parts at very high radiant temperature and emitting profuse hazardous fumes. The process is being manual by holding welding in nearest vicinity in head and object. This causes the exposure of high temperature welding fumes to the welders breathing zone. To get read of this occupational hazard Chasm invented a unique welding fume extraction system with extended arm. This help ergonomically compatible extraction system without creating any hindrance to the welder and compromising quality and quantity of welding process.
The Process of welding fume extraction normally comprises of well designed extended arms, Centralized steady ducting and High efficient silent blowers making system compact and designed for consistent operation. The achievers speak about experiences in our various clientele.