How are filter bags in dust collectors cleaned?

Clean air in a work place is a basis of health and safety for people and basis of industrial processes efficiency. That is the reason for which more and more companies decide to equip their plants with dust collectors or air filtration units, which eliminate dusts and other dirt particles from the air.
Regular and thorough cleaning of filter cartridges or bags is crucial to keep the dust collector operation at its best.

Filter bags – how do they work?

Filter cartridges are a key element of each dust collector. They differ in size, shape, type of filter fabrics, as well as their assembly method and treatement of the fabrics. The most popular filters are in a form of sleeves or bags made of polyester fabrics but there are also pleaded filters and cassette filters. The type of filters is selected to a given dust collector type and the dust characteristics the filter is going to work with. Diffrent filters are used for welding fumes and different ones for wood dust.

Filters task is to stop dust/dirt particles and let the clean air go through. The dusted air is either pushed or pulled through the filter bags fabrics (that depends on the dust collector operating system: push system – in which the dusted air is pushed into the dust collector and the dirt particles stop on the outside of the filter fabrics, or pull system – in which dusted air is pulled/vacuumed into the inside of the filter bags/sleeves).

The filter fabrics is made of various fibres such as polyesther, polyacrylics, polyamids and their blends – all these materials have high mechanical, thermal and chemical resistance. The filter fabric is also treated to obtain additional resistance or specific properites such as: acid resistance, hydrophobic, oilphobic or antistatic properties – so important in dust collection.

As every type of filter, filter bags (sleeves) also require regular and effective cleaning (often called regeneration). The cleaning aims at prolonging the proper functioning of the filter fabircs and remove the dust composition either from the inside or outer surface of the filter bags. Cleaning system depends on the dust collector and the system it works pull or push described above.

Filter bags cleaning methods

One of the most popular cleaning methods is with the use of compressed air. The blows of compressed air are directed into the filter bags and the dust gathered on their outer surface is blown off. Another method, a more energy saving one, is with the use of regenerative fans, which located directly above the filter bags clean them with reverse air blows. In this method filter bags are cleaned in a cyclical manner.

Antoher cleaning method is shaking – filter bags are assembled on a frame connected to actuators which shake the frame with the filter bags energetically. This way the dust is shaken off the filter bags.

Regular cleaning of the filter bags is indispensible for the proper functioning, long operation and efficiency of the dust collector. The frequency of cleaning depends on many factors that need to be considered individually for a given system. The factors that influence the cleaning are, among others: moisture content in filtered air, dust type and quantity and operating temperature, etc.