Baghouse Filtering Views
Cartridge collectors are another commonly used type of dust collector. Unlike baghouse collectors, in which the filtering media is woven or felt bags, this type of collector employs perforated metal cartridges that contain a pleated, nonwoven filtering media. Due to its pleated design, the total filtering surface area is greater than in a conventional bag of the same diameter, resulting in reduced air to media ratio, pressure drop, and overall collector size.
In a baghouse, dirty air flows into and through a number of cloth filter bags that are placed in parallel. The filters remove the particulate from the gas stream while the cleaned gas passes thorugh the cloth and is exhausted to the atmosphere. The fabric filters do some filtering of the dust particles; however, their more important role is to act as a support for the layer of dust (filter cake) that quickly accumulates on it. This layer then acts in a highly efficient manner to filter both the large and small particles from the gas stream and becomes the main filtration mechanism throughout the process.
The baghouses are named after the method used for cleaning the dust and filter cake from the bags. These include the shaker baghouse, reverse-air baghouse, pulse-jet baghouse, and sonic horn baghouse. In the shaker baghouse, the dusty air flow is taken offline and the isolated bags are shaken to knock off the dust. In the reverse air baghouse, the dusty air flow is blocked from the compartment to be cleaned and the clean air is forced to flow gently backwards through the bags thus dislodging the particles. In a pulse jet baghouse a blast of compressed clean air flows brieftly into the bags, while they are still filtering dusty air. In a sonic horn baghouse, a pulse from a sonic horn is sent through the bags to dislodge some of the dust. In all of these baghouses, the particlulate falls down from the filters and is collected in a hopper where it can be removed.
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.
Baghouse Filtering Images
