Baghouse BAG

The basic filtration process may be conducted with many different types of fabric filters in which the physical arrangement of hardware and the method of removing collected material from the filter media will vary. The essential differences may be related, in general, to 

Discuss the various cleaning methods employed in baghouses. 

Calculate the overall efficiency of a baghouse consisting of three compartments treating 9000 acfm of gas with an inlet loading of 4gr/ft. The first and third compartments operate at a fractional efficiency of 0.995 while the second compartment operates at a fractional efficiency of 0.990. What is the overall efficiency of the baghouse if the flow and inlet concentration are evenly distributed Also calculate the efficiency if the following flow distribution exists  

Write the equation for the outlet concentration, Cjq, from module 1 in terms of c, and Ex-. 

The equation for the outlet mass flowrate, mi, from module 1 is For module i, 

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Bagasse fiber Bagels Bag filters Baghouse Baghouses... 

Direct water spray cooling must be carried out with care. The spray chamber must be designed to ensure complete evaporation of all Hquid droplets before the gas enters the baghouse. Spray impinging on the chamber walls can result ia a dust mud iaside the chamber and any increase ia gas dewpoint may result in baghouse problems or atmospheric plume condensation. Spray nozzle wear can result in coarse or distorted spray and wetted bags, and water pressure failure can cause high temperature bag deterioration. 

Air cleaning systems are often used to remove dust or vapors from plant or process exhaust streams. Dust collecting systems such as filters or electrostatic precipitators that handle heavy loads of dust are usually designed to be self-cleaning, but it is stiU. necessary to enter the air cleaner periodically for inspection or repair. Dust deposits inside the equipment are likely to be stirred up and inhaled by unprotected workers. Baghouses are particularly likely to cause exposure because large amounts of dust may be retained in the cloth and released when the bags are handled. 

Gases from the furnace, metal tap, slag tap, and feed system are combined and fed to a sis-ceU pulse baghouse containing 864 high temperature Teflon bags. The dust from the electric furnace system is fed continuously back to the reverberatory furnace in a close screw conveyor. 

Dried product is collected in either cyclones or baghouses depending upon the product-particle size. When primary coUection is carried out in cyclones, secondary collection in a baghouse or scrubber is usually necessary in order to comply with environmental regulations. A rotary valve is used to provide an airlock at the discharge point. Screws are utihzed to combine product from multiple cyclones or large bag-houses. If required, a portion of the dried product is separated from the main stream and returned to the feed system for use as backmix. 

Particulate Emissions To meet environmental regulations, AFBC boilers, and some PFBC boilers, use a back-end particulate collector, such as a baghouse or an electrostatic precipitator (ESP). Compared to PC units, the ash from FBCs has higher resistivity and is finer Decause the flue-gas path contains cyclones. Both factors result in reduced ESP collection efficiency with AFBC units, but good performance has been achieved with PFBC units, where the SO3 present in the flue gas lowers the ash resistivity. In general, however, bag-houses are the preferred collection devices for both AFBC and PFBC apphcations. 

Industrial filtration systems may be of many types. The most common type is the baghouse shown in Fig. 29-3. The filter bags are fabricated from woven material, with the material and weave selected to fit the specific application. Cotton and synthetic fabrics are used for relatively low temperatures, and glass cloth fabrics can be used for elevated temperatures, up to 290 C. 

You wish to design a baghouse to clean 3000 m at a filter ratio of 3 m m of cloth. The filter bags are 15 cm in diameter by 3 m long. If you design a "square" baghouse with... 

For a detailed development of tlie above equation, refer to Effect of Bag Failure on Baghouse Outlet Loading, L. Tlieodore and J. Reynolds, JAPCA, August 1979, 870-2. 

If T is tlie failure of a bag in a baghouse in 50 days with standard deviation 1.0,... 

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