Baghouse performance

Determinants of baghouse performance include the fabric chosen, the cleaning frequency and methods, and the particulate characteristics. Fabrics can be chosen which will intercept a greater fraction of particulate and some fabrics are coated with a membrane with very fine openings for enhanced removal of submicron particulate. Such fabrics tend to be more expensive. 

The choice of filter medium and fabric construction is important to baghouse performance. The fabric filters are constructed from both natural and synthetic materials, and the selection is usually made on the basis of the following factors [2] ... 

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. 

Cartridge collectors perform very effectively in many different applications. Common applications of cartridge filter systems with pulse jet cleaning are comparable to baghouses described earlier. In addition to these applications, cartridge collectors can be used in any process where dust is generated and can be collected and ducted to a central location. 

Smith, E. M., and R. L. Lucas. Information Required for the Specification and Performance Evaluation of Industrial Baghouses (Fabric Filters). /. Air Pollution Control Assoc., 25, no. 7, (July 1975), pp. 715-720. 

The primary measure of baghouse-system performance is its ability to consistently remove dust and other particulate matter from the dirty-air stream. Pressure drop and collection efficiency determine the effectiveness of these systems. 

Most baghouse systems are provided as complete assemblies by the vendor. While the unit may require some field assembly, the vendor generally provides the structural supports, which in most cases are adequate. The only controllable installation factors that may affect performance are the foundation and connections to pneumatic conveyors and other supply systems. 

This operation is also performed using machines. The cured plates are fed into the parting machine by mechanical means. The plates are parted in the machine and then collected when the operation is completed manually. The parted plates are thereafter stacked for use in battery assembly. More rejects are also generated in this section as well as some lead dust. The ventilation system in this area ensures that the lead dust generated is removed from the work area and discharged into the atmosphere through a baghouse filter. 

Organic-bound lead and sulfur compounds can reduce catalytic oxidizer performance and increase treatment costs due to added maintenance requirements. The pulse-jet baghouse is unable to remove submicron particulates from exhaust gases. The LTTD is unable to treat contaminants with boiling points greater than 900°F. 

Whether burning tires or TDF improves or deteriorates emissions appears to depend on the control devices installed. ESP s seem to work the best for controlling emissions while burning tires or TDF. It is believed that the zinc content actually helps the ESP perform better, and this improved performance is seen in reduced emissions. Fabric filters (baghouses) also seem to be well suited for the control of emissions while burning tires or TDF. 

Commercially available baghouses employ either felted or woven fabric. A fabric is selected based on its mechanical, chemical, and thermal characteristics. Some fabrics (like nomex) are better suited than others (like polyester) for high temperature operations, some perform well in the presence of acid gases, while others are especially good at collecting sticky particulates because of good release characteristics. 

The two design and operational parameters that determine fabric filter performance are air-to-cloth ratio and pressure drop. The air-to-cloth ratio is the volumetric flowrate of the gas stream divided by the surface area of the fabric. The higher the ratio, the smaller the baghouse and higher the pressure... 

It should be noted that varying the baghouse cycle rate over the range 6 to 30 minutes also had no apparent effect on S02 removal. This was found to be true in all other tests performed, regardless of the sorbent employed. It is believed that this is an indication that reactions are confined to only a thin outer layer of sorbent deposited on the filter bags. 

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