Power Generation

Development status of bag filter in power plant

The power plant boiler dust collector has gone through the process of dry cyclone dust removal, multi-tube cyclone dust removal, water film dust removal and electrostatic dust removal. At present, with the country's increasing emphasis on environmental protection and the increasing requirements for environmental protection, as well as the localization of filter bags and the extension of service life, the dust removal at the tail of boilers in thermal power plants is returning to bag dust removal.

With the further improvement of the level of science and technology, recently, the categories of bag filter in my country are basically complete, and its product type and performance can basically meet the needs of boiler dust removal. Its technical development is mainly reflected in the following aspects.

• (1) Improvement of the structure of the bag filter. The bag filter has developed from a small single-chamber structure to a multi-chamber structure, and the filtration area has developed from a few square meters to tens of thousands of square meters. Compact and lightweight bag filter technology.
• (2) Technological progress of ash cleaning system. The cleaning system is the digestive organ of the bag filter, and the operation effect of the bag filter depends to a large extent on the cleaning mechanism and its control system. At present, my country has adopted international standards to design and develop high and low pressure pulse valves. The injection pressure has been reduced from 0.5~0.7MPa to 0.15~0.25MPa. For the pulse injection bag filter, the original high-pressure orifice pulse was developed on the basis of Large low pressure long bag pulse technology. The control system program is developed from time sequence to constant resistance type, from open-loop control to closed-loop control, and the grade of controller is developed from relay logic program controller to single-board computer, single-chip computer, programmable controller, and multi-function computer controller. The functions of the control system range from two-place control, status display, fault alarm to sub-chamber leak detection, data processing, and printing of reports.
• (3) Developed and applied auxiliary cleaning technology, such as pre-coating technology, preload technology, sonic cleaning technology, etc.
• (4) The technology of filter material and filter bag has been greatly improved.
• (5) The manufacturing process and production equipment of the bag filter are gradually on the right track, and a complete process line has been established.
• (6) Gradually established the bag filter software data, formulated the national, professional and enterprise three-level standards, which played a positive role in the manufacture of dust collectors, the development of new products and the acceptance.

In the 1980s and early 1990s, my country used bag filter in several small coal-fired units. Due to the limitation of conditions, it did not persist. The main reason was that the overall level of bag filter was still relatively backward. , The large-scale pulse back-flushing bag filter with reliable performance has not been developed, and there is no filter material with good strength, high temperature resistance, corrosion resistance and long life suitable for coal-fired power plants in my country; the domestic pulse valve is not enough. The service life is short; the processing and installation of other components are not very good, and the knowledge and experience of the bag filter are not enough, so there are "burning bags", "paste bags", "leaking bags", "stuck" ", "poor cleaning" and so on.

In the past ten years, the bag filter has developed rapidly, especially the emergence of large bag filter, the development of new filter materials and new pulse valves, making the bag filter safer and more reliable than the electrostatic precipitator. It has high efficiency and is little affected by dust characteristics and flue gas composition. It is believed that large-scale pulse bag filter with reliable performance will be popularized and applied in coal-fired power plants in the near future.