The Neundorfer KnowledgeBase is an industry-leading information resource about baghouses/fabric filter operations, providing a great starting point for background information or details on specific topic areas of interest.
The downloadable manuals at the right are made available by the Environmental Protection Agency (EPA) at www.epa.gov and provide detailed information about baghouses/fabric filter operations. For a glossary of terms related to baghouses/fabric filter operations, reference the download available at the right.
About Baghouse/Fabric Filter Operations
As with electrostatic precipitators (ESPs), baghouses (abbreviated B/H or referred to as fabric filter/FF operations) are particulate air pollution control devices, but the process and operation is different. Since the late 1970's, with the introduction of high-temperature fabrics (> 350 degrees Fahrenheit), the baghouse has become increasingly popular, especially in the utility market. In contrast to ESPs, the baghouse is a highly efficient particulate collection device regardless of the incoming dust loading or particle size. Also, with new, stricter EPA regulations forthcoming for the removal of gases and heavy metals, the baghouse offers adaptability as a dry collection device using absorbents.
Baghouse Principles of Operation
Dust enters the baghouse compartment through hoppers. Larger particles drop out while smaller dust particles collect on filter bags. When the dust layer thickness reaches a level where flow through the system is restricted (called pressure drop or delta P), the bag cleaning process is initiated. Cleaning can be done while the baghouse is still online (filtering) or in isolation (offline). Once cleaned, the compartment is placed back in service and the filtering process starts over.
Types of Baghouses
There are three prominent types of baghouses: Reverse Air (Gas Cleaning), Pulse Air (Compressed Air Cleaning) and Shaker (Mechanical Cleaning). Baghouses are classified by their cleaning method:
Reverse Air (Gas Cleaning)
Pulse Jet (Compressed Air Cleaning)
Shaker Baghouse (Mechanical Cleaning) or Combination-Style Plenum Pulse or Shaker/Reverse Air
Cleaning sequences can be:
- Intermittent (Single compartment, generally Shaker-type in which the fan/process must be stopped while the bags are cleaned)
- Continous Offline (Multiple compartments for a reverse air or pulse jet; each one is taken offline to clean but the overall process is not shut down)
- Continuous Online (Full automated, usually for a pulse jet baghouse; the process flow continues during cleaning)
Misconceptions About Baghouses
- Fabric filter bags do not filter (except for PTFE bags)
- The dust layer (dust cake) filters fine particles
- The primary function in bag life reduction is the cleaning frequency and energy
- Overcleaning bags is worse than undercleaning because bags wear out from cleaning (not filtering)