What are filters and how do they operate?
A filter is a mechanism which is designed to act as an air pollution control device. They work to remove solid particulates from air and gas, which have been released by commercial processes, such as; power plants, food manufacturers and chemical producers.
Common types of filter include but are not limited to; Pulse Jet Filters, Reverse Air Filters and Shaker Filters. Each of these are formed by cylindrical bags of fabric, which are used to draw through dusty air and gas and collect unwanted particulates on their surface. This filtration process is achieved by the following four mechanisms:
Interception– This mechanism occurs when particles which are following the gas or air stream, come into contact with fibers of the filter and are thus captured and removed from the gas and air flow.
Inertial Collection– Unlike small particles which have less inertia, large particles are often unable to change direction, in response to changes in a gas or airway direction. In the presence of a fiber filter, the path of large particles will therefore remain unchanged and they will instead collide with the filter surfaces.
The Brownian Movement– is the random movement of microscopic particles as a result of their collision with fast-moving molecules . This causes a diffusion of particles which increases the likelihood that they will make contact with the filter fabric surfaces and thus be captured.
Electrostatic forces– a filtration method which removes fine particles and contaminants using the force of an induced electrostatic charge. Particles become positively charged by the friction between the air and the filter. This causes air molecules to become attached to the filter fabric as they pass through it.