Baghouses systems pressure drop

Gas Filtration Vendors are the primary source for sizing baghouses, however the process engineer should at the very least make an estimate of the pressure drop requirements for an intended system. The pressure drop will, of course, provide information needed on the approximate size of the fan needed, and the energy requirements needed to operate a system. In fact, pressure drop is the primary parameter in establishing particle removal efficiency for a fabric filtration unit, and hence, is usually the starting place for discussions with the equipment supplier. 

Proper operation of a baghouse, regardless of design, depends on frequent cleaning of the filter media. The system is designed to operate within a specific range of pressure drops that defines clean and fully-loaded filter media. The cleaning frequency must assure that the maximum recommended pressure drop is not exceeded. 

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. 

A calcium hydroxide plant is required to treat the exhaust fume generated from the plant. The ash generated from the system is collected at the bottom of the baghouse while the exhaust gas flow of 350,000 acfm enters the baghouse with a loading of 6.0gr/ft. The air-to-cloth ratio is 8.0 and the operating particulate collection efficiency is 99.3%. The maximum allowable pressure drop is 10 in. H2O. The contractor s empirical equation for the pressure drop is given by... 

A key research area is the study of the effect of selective catalytic reduction (SCR), selective noncatalytic reduction (SNCR), dry particulate adsorbent injection, and SOx removal systems on the removal efficiency, pressure drop, and lifetime of the baghouses. The use of fabric filters in PC boilers is increasing every year due to the stringent particulate emission standards. Pennsylvania Power and Light was the first utility to install a bag-house in 1973, and up until 2005, more than 129 RGFFs were installed on 28 GW of power plant capacities [64] (Figure 18.10). 

Obviously, if pressure drops on the order of 6 to 8 kPa are acceptable from a process point of view, an 8 or 13-unit multicyclone (or some number in between) could prove to be a viable option for the task at hand. If not, other types of separation equipment may have to be considered such as a baghouse, an electrostatic precipitator, or a wet scrubber. Nevertheless, even if the pressure drop across the cyclones were acceptable, one would still need to consider the long-term wear implications associated with operating the cyclones at velocities in the range of 35 to 40 m/s. If the solids being processed are not especially abrasive and/or if they are sufficiently flne in size, it may be possible to operate at these velocities. If not, erosion-protective liners may need to be installed. Some bare-metal multicyclone systems have been observed to operate for many years at velocities of 70 to 85 m/s while processing several tons per day of rather abrasive sand-like particles that were under about 25 fim in size. 

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