Types of Dust Collection Equipment
Dust collection equipment removes contaminants and harmful matter from the air in production facilities, workshops and industrial complexes. It also helps facilities stay compliant with major regulatory bodies like the Occupational Safety and Health Administration and National Fire Protection Association.
Baghouse systems use long cylinder-shaped bags made from woven fabrics that act as a filter. The system has methods of cleaning the filter: shaker or pulse-jet.
Baghouse
Baghouse dust collectors filter fine particles from air using a filter bag. As the particles settle on the bag, they form a layer called a dust cake that prevents airflow and requires the system to be cleaned. Baghouses can be classified based on their cleaning method: reverse air, shaker, and pulse jet.
When a baghouse system needs to be cleaned, the air is pulled into a compartment of the unit and the bags are mechanically shaken, removing the dust cake. This process is slow and requires the system to be taken offline for a lengthy amount of time.
Pulse jet baghouse systems use Venturis or air nozzles to increase the pressure of the clean air used to replace the dirty air. This quick and effective cleaning process keeps the system online and is more cost-effective than reverse air baghouses.
The most common baghouse filters are Dust purification equipment woven fabric designs, but there are also non-woven or needle felt options available. Choosing the best filter for your application depends on factors like particle size and density, gas volumetric flow rate, and opacity.
Cyclone
A cyclone dust collector draws air through a helix-shaped baffle inside the device. The helix is wider at the top and tapers down to an inverted cone shape. This causes the air to move helically, and heavier dust particles are carried down toward the bottom by centrifugal force. They drop into a collection bin, while clean air spirals upward to the filter. Cyclone equipment is often used in metalworking, glass-making and similar industries. Its primary benefit is that it reduces clogged filters and receivers. It also improves employee health by preventing the fine dust particles from exiting into the air and causing respiratory problems.
A dust collection system should have gas and particulate data at the cyclone inlet, including analysis of gases and a description of how the efficiencies and pressure drops were determined. It is important to use this data to properly size and configure the cyclone for the application, which will minimize equipment costs.
When shopping for a cyclone dust collection, the power rating of the electric motor is an important consideration. Its HP count determines how well the device works. However, a cyclone’s design and capacity are also crucial factors in choosing the right product for the job at hand. The wrong size or type of cyclone can cause the equipment to overheat and fail.
Electrostatic Precipitator
The electrostatic precipitator (ESP) is a device that uses electrical forces to separate dust particles from a gas stream. It can be used for dry or wet dust purification. An ESP can remove large, coarse dust from air as well as fine dust and liquid droplets. This type of device can also capture hazardous air pollutants, such as sulfuric acid mist and nitrous oxides. It can be a standalone unit or an in-duct system.
An ESP works by creating an electric field that charges the dust particles, making them stick to the collection surfaces. The ions and free electrons in the gas stream make these particles adhere to the collecting surface, which is usually made of plates or wires. It is then sucked up into a collector hopper.
The ESP consists of several components, including gas distribution plates, discharge electrodes, and collection surfaces (plates or pipes). It is connected to an AC power supply through a transformer-rectifier set. This supplies the ionization and high voltage that creates the electric fields in the discharge electrodes. These ions and free electrons are then applied to the dust particles in the gas stream. The particles then become charged with a negative charge and are attracted to the collection plates, which have an opposite polarity. A mechanical portion of the ESP strikes these plates periodically to release the dust layer into the hoppers.
Cartridge
Cartridge-type dust collectors use cylinders that are open on one end and lined with a pleated nonwoven filter media. They are typically Dust purification equipment used in applications that require a clean work surface such as blast cleaning, sanding, laser/plasma cutting and certain welding processes. They are also well-suited for applications where the particle sizes vary and a progressive filtration approach is needed, such as powders and bulk materials or where stringy or sticky particles may be present.
The dirty air moves into a space between the filters, which is called the DIRTY AIR PLENUM. The filtered air is then vented out the other end of the system, leaving the dust in a collection hopper beneath the filters.
Industrial dust filter change-outs and regular maintenance will keep a cartridge dust collector running at optimum efficiency, saving both energy and money. Dirty filters restrict air flow, making the system work harder to catch and hold particles – even if they are rated at high efficiency levels.
For optimal performance, the cartridge dust collection system should include a pre-filter on the inlet to remove heavy, coarse material, followed by a medium efficiency (MERV 13-15) filter for mid-sized particulate. A HEPA after-filter will then remove the fine and ultrafine particles. Depending on the application, the filter media may be a spunbond or nanofiber, with optional anti-static or fire-retardant coatings.
