(Article updated 12/19/2019)

Baghouses, also called fabric dust collectors or fabric filters, are air pollution control devices designed to use fabric filter tubes, envelopes or cartridges to capture or separate dust and other particulate matter (PM). Their applications range from small household workplaces to large industrial facilities such as coal-fired power plants and cement plants.

Bag-in/bag-out equipment. Source: Camfil Air Pollution ControlBag-in/bag-out equipment. Source: Camfil Air Pollution Control

Compared to other types of air pollution control (APC) equipment, baghouses are incredibly versatile and can be engineered for almost any dust-producing application by varying size and bag types. They are very efficient when properly maintained and are also rugged enough to handle rough applications. However, they typically require a lot of maintenance and a relatively dry environment to operate effectively. Their use is also limited to certain operating temperatures and chemical conditions.

Baghouse collector operation

Red arrow indicates dirty air, blue arrow indicates clean (filtered) air. Source: Neundorfer Inc.Red arrow indicates dirty air, blue arrow indicates clean (filtered) air. Source: Neundorfer Inc.Baghouses consist of filter media (bags) suspended inside a housing or casing. Fans on the outside of the housing blow the dirty or polluted air through the filters, capturing the suspended particulate matter and solids on the bags and pushing clean air through the outlet. While filtering, a baghouse bag allows the formation of a layer of particulate matter on its surface, called a dust cake.

This dust cake continues to build until the thickness reaches a level where the flow is sufficiently restricted; at this point, the bags are cleaned. Cleaning can be done during operation or offline depending on the type of baghouse.

As air is filtered through the baghouse, the dust cake on the bag filters continually thickens. For most bag fabrics (those without a membrane coating), the cake is what does most of the filtering of the particulate matter in the air stream. A thicker dust cake increases both collection efficiency and pressure drop as the pathways through the bag become finer and also more restrictive.

Cleaning mechanisms must find the right balance for this tradeoff — too thorough or frequent cleaning results in lower collection efficiency and possibly reduced bag life, but insufficient cleaning will cause excessive energy requirements for blower fans (for example, high pressure drops).

To read more, click here.

Discover more

Subscribe to Engineering360 newsletters for industrial and engineering news and information:

Environmental Technology

Industrial Processing Equipment

Plant & Facilities Engineering

Process Technology

To contact the author of this article, email GlobalSpeceditors@globalspec.com