Baghouses
by Stephen_HP on 2007-09-24Baghouses generally operate in the temperature range of (120-180°C); these have been more widely used since the 1970s, especially at the industries scale. Baghouses are used to prevent particles created by industrial process. They work like vacuum cleaners. Baghouses are known to be one of the most effective and widely used control devices for fine particulate matter. Our local air pollution control districts adopt regulations that limit maximum participate out flow and the visibility of emissions from industrial process. Baghouses require pulse cleaning. Baghouse performance involves the use of flow controls to evenly distribute the particulate laden gas stream to each compartment and protective devices to prohibit premature filter bag wear.
The choice of a fabric filtration generally depends on the type of coal, plant size and boiler type and configuration. There are three types of fabric filters. They are based on the cleaning mechanisms. Controls are developed both to meet the levels of inlet and outlet gas flow uniformity specified for optimum baghouse performance. Bag houses use filter bags that must be purchased, inventoried and discarded when the bag reaches capacity. Baghouses are used in food processing. The two fundamental parameters in sizing and operating baghouses are Air to cloth (A/C) ratio (m/s) and the pressure drop (mm water gauge, Pascal's or in.H2O). The other important factors which affect the performance of the bag houses are the:
Flue gas temperature.
Dew point.
Moisture content.
Particle size distribution.
Chemical composition of the fly ash.
Baghouses Application
Baghouses are fabricated in mild steel, stainless steel, titanium, and other materials. They also supply ducting, access platforms, ventilation and instrumentation. Also made for dusts of 3 microns and larger, in these applications:
Woodworking.
Material handling.
Powder processing.
Primary metals, including steel-making.
Papermaking.
Metals fabrication like grinding, sawing, sanding, polishing.
Ceramics manufacturing.
Mixing and blending operations.
Mining.
Almost all the industries are need of bag houses because they let out lot of pollution and law is also against this fact. To stay away from the law, and attract workers to your industry you need to keep your industry neat and clean.
Both ESP's and fabric filters are highly efficient particulate removal devices with design efficiencies in excess of 99.5%. Particulate removal efficiencies in ESP and fabric filters can be further improved by flue gas conditioning. Baghouses are increasing their market share year by year but mainly in industry. The choice between ESP and baghouses generally depends on coal type, plant size and boiler type and configuration.
Conditioning the fly ash in the flue gas is an established technique used to restore the performance of an ESP in coal-fired power plants with high-resistivity fly ash resulting from burning low sulphur coals. The benefits of flue gas conditioning in fabric filters include achieving lower emissions at higher bag air to cloth ratio, reducing pressure drop and improving fly ash cake cohesivity thus leading to better dislodgement in larger agglomerates and less re-entrainment. Elemental sulphur, ammonia (NH3), and sulphur trioxide (SO3) are the main conditioning agents currently used.
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