A Bag Filter for a boiler is an air pollution control device used to remove particulate matter (like dust, soot, and ash) from the flue gases generated during the combustion process in a boiler. It is a type of fabric filter that uses a collection of fabric bags to capture and filter out solid particles from the exhaust gases before they are released into the atmosphere.
Key Features of a Bag Filter for a Boiler: Fabric Filter Bags: The core of the bag filter consists of a series of fabric bags, typically made from materials such as polyester, polypropylene, or fiberglass, depending on the temperature and type of particles being filtered. These bags act as a physical barrier that captures particulate matter as flue gases pass through them.
Dust Collection: As flue gases pass through the bag filter, the solid particles (such as dust, ash, and soot) are trapped in the fabric bags. Cleaned gases then pass through the filter and are released into the atmosphere or directed to other treatment processes.
Pressure Drop: A bag filter operates under the principle of pressure difference. The gases flow from the outside to the inside of the fabric bags. The particulate matter gets trapped on the outside of the bags, and the cleaned gases flow through the bag and exit the filter.
Cyclic Cleaning: Over time, the bags accumulate particulate matter, which can reduce the filters efficiency. To prevent clogging, bag filters are periodically cleaned using various cleaning methods:
Pulse Jet Cleaning: This method involves periodically injecting compressed air into the bags, causing them to expand and release the trapped dust.
Shaker Mechanism: The bags are shaken to remove accumulated dust.
Reverse Air Cleaning: Air is blown in the opposite direction through the bags to dislodge the particles.
Dust Collection System: The particulate matter that accumulates on the bags is collected in a hopper or bin at the bottom of the bag filter. This dust can either be disposed of or, in some cases, reused, depending on the type of fuel and the particulate material.
Efficient Filtration: Bag filters are capable of achieving high particulate removal efficiencies, often greater than 99%, depending on the size of the particles and the type of fabric used.
