The Bag House/Bag Filter is generic name of Air Pollution Control Equipment. It is designed around the use of engineered fabric, filter tubes, envelopes or cartridges in capturing dust, separating dust or filtration process. AIL provides reliable and highly efficient Bag Filters and Bag House systems.
The dust laden gas enters through inlet nozzle and spreads all over the entire cross section of the bag filter. The gas moves up & passes through the bags, enters the clean air plenum through the top open end of the bags. During the passage of the gases through the fabric, the dust is retained on the outside surface of the bags. As the filtration proceeds the thickness of the dust layer on the fabric surface increases resulting in increase in pressure drop across the fabric. This necessitates the cleaning of the bags. Since the air flow is from outside to inside, the bags tend to collapse and are held by the wire cages, whose shape they acquire. The compressed air passing through the solenoid valves injects air at very high velocity for a short duration. This produces a shock wave causing the bag to expand and dislodging the dust cake which falls into the hopper. This unit is generally meant to operate with a pressure differential of 100-125 mmWG.
In an online bag filter system, bags are cleaned row by row, even when the dust laden gas is entering the casing. The sequence of cleaning is controlled automatically by a sequence controller. This operates the assembly of solenoid valves which direct the air flow into the manifolds. The holes are perfectly aligned with the venturi centre for achieving maximum cleaning efficiency.
Similar to Cyclone, AIL also manufacturers Multiclone Dust Collectors wherever application of the cyclone could not serve the purpose and Multiclone can provide higher efficiency. Multiclone Dust Collector consists of a number of small-diameter cyclones, operating in parallel and having a common gas inlet and outlet, as shown in the figure. Multi-clones operates on the same principle as cyclones, creating a main downward vortex and an ascending inner vortex. Multiclones are more efficient than single cyclones because they are longer and smaller in diameter. The longer length provides longer residence time while the smaller diameter creates greater centrifugal force. These two factors result in better separation of the dust particles. The pressure drop of the multiclone collectors is higher than that of single cyclone separators.
This mode incorporates the advantages of pulse jet bag filters, as well as that of a reverse air bag house. Each compartment is similar to an online pulse jet bag filter. The cleaning process consists of sequentially isolating each compartment and cleaning it with compressed air. All compartments are then cleaned automatically. Offline cleaning is suitable for light and fine dust and for larger volumes where the occurrence of fluidization is a distinct possibility.
The offline bag filter generally contains 4 to 6 bag filter compartments. Each compartment is similar to online bag filter. Gas flow through a compartment is stopped temporarily when the pulse cleaning of the bags is to be done. The dust dislodged from bags settles quickly in the hoppers because of absence of gas movement in the bag filter compartment. During this time the remaining compartments keep filtering the gases as usual. Each compartment is cleaned one after another in the same manner. The starting and stopping of gas flow through individual compartments is achieved through a compact pneumatic damper system.
