Fabric-filter systems

TABLE 25-17 Advantages and Disadvantages of Fabric-Filter Systems... 

Fabric-filter systems, commonly called bag-filter or bag-house systems, are dust-collection systems in which dustladen air is passed through a bag-type filter. The bag collects the dust in layers on its surface and the dust layer itself effectively becomes the filter medium. Because the bag s pores are usually much larger than those of the dust-particle layer that forms, the initial efficiency is very low. However, it improves once an adequate dust-layer forms. Therefore, the potential for dust penetration of the filter media is extremely low except during the initial period after startup, bag change, or during the fabric-cleaning, or blow-down, cycle. 

It is proposed to install a pulse-jet fabric-filter system to remove particulates from an air stream. Select the most appropriate bag from the four proposed below. The volumetric flow rate of the air stream is 10,000 std ft3/min (4.72 m3/s) (standard conditions being 60°F and 1 atm), the operating temperature is 250°F (394 K), the concentration of pollutants is 4 grains/ft3 (141 grains/m3), the average air-to-cloth ratio is (2.5 ft3/min)/ft2, and the required collection efficiency is 99 percent. 

Eliminate from consideration any bags that are patently unsatisfactory. Bag D is eliminated because its recommended maximum temperature is below the operating temperature for this application. Bag C is also eliminated, because a pulse-jet fabric-filter system requires that the tensile strength of the bag be at least above average. 

There are several equations provided in the literature to describe pressure drop in a fabric filter system. The form most often used is... 

It is proposed to install a pulse-jet fabric filter system to clean an airstream containing particulate pollutants. You are asked to select the most appropriate filter bag fabric considering performance and cost. Pertinent design and operating data, as well as fabric information, are given below. 

Fabric filter systems (e.g., baghouses) are among the oldest and most widely applied particulate emission control devices. Dust filtration in baghouses is... 

Huang, H., Allen, J.W., and Livengood, C. D., 1988, Combined Nitrogen Oxides/Sulfur Dioxide Control in a Spray-Dryer/Fabric-Filter System, ANL/ESD TM-8, Argonne National Laboratory, Argonne, IL, November. 

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