Industrial Air Filtration require filters that will remove solid particles from the airstream. The air from which particles must be removed is known as process air. As is implied by the name, air is a requirement for manufacturing the end product such as steel, cement, aspirin, metal castings, numerous chemical compounds (Kaolin, TiO2). Also anywhere a fire is part of the (pyro) process, like burning coal to produce electricity. Process air can contain the desired end product as well. Examples of product recovery are powdered milk, baby powder, rice and many more. Process air is even involved in the repurposing of existing products: Take for instance used automotive batteries. The lead from all our automotive batteries must be reclaimed because lead is classified as being hazardous to our health. It cannot be sent to a landfill.
Product Recovery
Air is used to transport solids through the process or used for combustion of fuel. Many of the production processes begin as a solution of solids and water. Process air is needed to remove the moisture which in turn creates the solid to be collected such as in the manufacture of powdered milk. The “Product Recovery” side of industrial filtration tends to be a closed loop systems. First because the value of the product and also the disposal of the waste is costly. A closed loop system is one in which the process waste is returned back into the process instead of disposing of it.
Pollution Control
Pollution unwanted particles being released into the atmosphere. Acceptable outlet loading is specified by the EPA. Filters used to clean up air that is released to atmosphere are referred to as pollution control devices. Examples of these processes are; Steel, coal fired boilers, Asphalt, Foundry, Incinerators, Waste to Energy and Wood.
Commonality
There are a huge numbers of manufacturing processes that will require the use of process air filters. The size and shape of the filters are determined by the Original Equipment Manufacturer (Bag House) based on the unique needs of the manufacturing process. The filter media choices from which the bags are made is dictated by the process air. Fortunately, a vast number of processes can be grouped into 15 or 20 filter media types. The first grouping of filters is normally by the temperature of the air required to produce the product. Media type fall into temperature ranges, < 200F, 200 F to 300F, 300F to 400F and 400F to 500F. The second grouping would be decided by the chemistry the filter is exposed to. Is the filter going to be subjected to an Acid or Alkaline environment? Will it see moisture at elevated temperatures?
The decision methodology as to which filter to use is very similar for both product recovery and pollution control filters. Every bag house that a filter goes into will be uniquely engineered to best suit the process air.