Table 1095 Advantages And Disadvantages Of Fabric Filter Systems

Advantages:

High particulate (coarse to submicron) collection efficiencies Dry collection and solids disposal

Relatively insensitive to gas stream fluctuations. Efficiency and pressure drop are unaffected by large changes in inlet dust loading for continually cleaned filters Corrosion and rusting of components usually not a problem

No hazard of high voltage, simplifying maintenance and repair and permitting the collection of flammable dust Use of selected fibrous or granular filter aids (precoating) which permits the high-efficiency collection of submicron smokes and gaseous contaminants

Filter collectors available in a number of configurations, resulting in a range of dimensions and inlet and outlet flange locations to suit a range of installation requirements Simple operation

Disadvantages:

Special refractory mineral or metallic fabrics (that are still in the developmental stages and can be expensive) required for temperatures in excess of 550°F Fabric treatments to reduce dust seeping or to assist in the removal of the collected dust required for certain particulates A fire or explosion hazard due to concentrations of some dusts in the collector (~ 50 g/cu m) when a spark or flame is accidently admitted. Fabrics can burn if readily oxidizable dust is being collected. High maintenance requirements (bag replacements, etc.)

Fabric life shortened at elevated temperatures and in the presence of acid or alkaline particulate or gas components Crusty caking or plugging of the fabric caused by hydroscopic materials, condensation of moisture (or tarry), and adhesive components which may require special additives Respiratory protection for maintenance personnel required in replacing the fabric Medium pressure-drop requirements, typically in the range of 4 to 10 in of water

TABLE 10.9.6 ADVANTAGES AND DISADVANTAGES OF ESPs

Advantages:

High particulate (coarse and fine) collection efficiencies with a relatively low expenditure of energy

Dry collection and solids disposal

Low pressure drop (typically less than 0.5 in of water)

Designed for continuous operation with minimum maintenance requirements Low operating costs

Capable of operation under high pressure (to 150 psi) or vacuum conditions Capable of operation at high temperatures (to 1300°F) Capable of handling large gas flow rates effectively

Disadvantages:

High capital costs

Sensitive to fluctuations in gas stream conditions (flow, temperature, particulate and gas composition, and particulate loading) Difficulty in collecting certain particulates due to extremely high or low resistivity characteristics Relatively large space requirements for installation

Explosion hazard when treating combustible gases and collecting combustible particulates Special precautions required to safeguard personnel from high voltage equipment Ozone produced by the negatively charged discharge electrodes during gas ionization Sophisticated maintenance personnel required metals that condense onto particulate matter. Effective mercury emission control technology, while evolving, has not been implemented in MSW incinerators. A volatile metal, mercury vaporizes under the high temperatures of combustion although recent research suggests that mercury can also be present as mercuric chloride, mercuric oxides, and mercury solids. Whereas most vaporized metals return to a solid state when combustion gases cool, mercury remains in the vapor state. Wet scrubbing, activated carbon and sodium sulfide technologies show promising results.

Mercury control requires that the vapor be adsorbed onto particulates or absorbed into a liquid which is evaporated to leave the solids. The mercury-laden solids are collected in traditional collection devices. Some technologies, used in conjunction with other pollution control systems, can simultaneously remove dioxins, furans, mercury, and other metals as well as acid gases and particulates (Seigies and Trichon 1993).

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