Technical and economic comparison between bag filter and electrostatic dust collector
1 electrostatic dust collector
a. Advantages: Dust removal efficiency is higher, up to 99%; pressure loss is small, body resistance is 100 ~ 200 Pa; mature technology, widely used;
b. Disadvantages: The equipment is large and covers a large area; high-voltage DC power supply system is required, and the one-time investment cost is high; it is sensitive to the some kinds of change, the dust removal efficiency is greatly affected by the fly ash resistance; the manufacturing, installation and operation management level is high.
2 bag dust collector
a. Advantages: Dust removal efficiency is very high, up to 99.98%; strong adaptability, can handle different types of particulate matter, especially high-resistance dust particles that are not easily trapped by electrostatic dust collectors; adaptable mass concentration range is large, It also has a certain stability to the change of the flue gas flow rate; the structure is simple and there is no complicated structure inside.
b. Disadvantages: The pressure loss is large, the body resistance is 800-1500 Pa; the application of large-scale units in China depends on imports.
Conclusions and advice
Through engineering practice, it is completely feasible to use the bag filter for the tail flue gas treatment of the boiler in the thermal power plant. It has high dust removal efficiency, one-time investment, small equipment space occupying (relative to electric dust collector above four electric fields), operating costs and sewage discharge charging is low. Especially in recent years, due to the development of manufacturing technology, the corrosion and wear of the filter bag have been effectively solved, which provides a powerful guarantee for the application of the bag filter. In addition, because the operation, fault and abnormal diagnosis of the dust collector is all automated monitoring and management, its operation and management is relatively simple.
2. Several matters should be paid attention to in the selection of bag filter
a. For coals that are difficult to collect by electrostatic dust collector (such as coal with SiO2+Al2O3 mass fraction greater than 85%, coal with extremely low sulfur content, coal with too high specific resistance), it is recommended to use a bag filter;
b. High requirements for the concentration of smoke and dust emission (not higher than 100mg/m3), it is necessary to use an electric dust collector with more than four electric fields, and it is better to use a bag filter;
c. For the unit that has been built, if the original unit adopts a water-film dust collector and a multi-tube ceramic dust collector and other dust-removing equipment with a large resistance, such as the water film dust collector, the calculated resistance is generally 1400 Pa, and the draught fan may not be replaced; if the original unit is electrostatic dust collector, the draught fan needs to be replaced or modified;
d. The electrostatic dust collector is transformed into a bag filter. The internal structure of the dust collecting body can be partially removed, and the housing, heat preservation and ash conveying equipment are retained to reduce the transformation cost;
e. When dealing with dusty gas with high relative humidity, heat preservation measures should be taken (especially in winter) to avoid “bag sticking” caused by condensation; when
corrosive gas is purified, suitable corrosion resistant filter material should be used. For the treatment of high temperature flue gas, cooling measures should be taken to reduce the
temperature of the fume to the temperature below that the filter bag can withstand for a long period of time, and use high temperature resistant filter material whenever possible.
Post time: Nov-19-2018