In China, bag filters are widely used in industries such as metallurgy, building materials, chemical engineering, and road construction. In the early 1980s, China also attempted to use bag filters on coal-fired power plant boilers. However, due to insufficient technical mastery at the time and limitations of objective conditions, problems such as short filter bag life, ash blockage, bag burning, high failure rate, and affecting unit operation were not successful. Nevertheless, valuable experience was provided for the application and development of bag filters in coal-fired boilers.
The working environment of bag filter is relatively harsh. In order to maintain and repair the dust collector well and extend its service life, inadequate maintenance and management of the dust collector can shorten its service life. Therefore, it is very important to maintain the dust collector well.
To fully utilize the role of bag filters, maintenance is also important. It is important to be able to use, inspect, identify problems, and deal with them in a timely manner. Dust collectors are usually used in environments with severe dust pollution such as steel, smelting, chemical, power generation, and cement. Maintenance and repair are essential for the normal operation of dust collectors and dust removal systems.
The box of the bag filter is the "outer shell" of the dust collector, and its maintenance and repair cannot be ignored. Always pay attention to tightening loose screws and replace them in a timely manner. During the operation of the dust collector, it is necessary to regularly check the working condition of the dust collector main unit and dust collector accessories, seal the parts that leak dust, especially the inspection door, observation hole, upper cover plate and other movable doors, and promptly brush the oil. The filling and sealing ring of the cover should be kept tight, and maintenance and upkeep should be done well. For parts of the dust collector that have been used for a long time or have paint peeling off, if aging or damaged packing is found to lose its sealing function, it is necessary to prevent the dust collector box from rusting.
The key to a bag filter is dust removal, and the effectiveness of dust removal determines the success or failure of the bag filter equipment and the entire system. Therefore, bag filters with dust removal as their characteristic have become equipment. The new generation of bag filter technology represented by bag filter overcomes the shortcomings of traditional dust removal, and its advantages in dust cleaning are prominent. It has the advantages of long filter bags (6m or longer), small footprint, low equipment resistance, low gas source pressure required for dust cleaning, less energy, and low work and maintenance workload. Weak cleaning bag filters generally have the phenomenon of high resistance. The dust removal efficiency of bag filter is further improved, and it is common for the emission concentration to be lower than 50mg/Nm3, and it is not uncommon for it to be lower than 10mg/Nm3. This is mainly because the filter bag interface technology of the host has made significant progress. In the past, the fixed bag method of binding or bolt tightening was adopted, and there was leakage at the filter bag interface, which often resulted in a difference of 1-2 orders of magnitude between the dust removal efficiency of the dust collector and the filter material. The new fixing method is to strictly control the processing dimensions of the bag holes and bag openings of the flower board, relying on elastic elements to embed the grooves on the outside of the bag openings into the bag holes. The two have a tolerance fit and good sealing, thus preventing leakage at the interface. The trend of large-scale bag filter is obvious, and its performance has reached a certain level. The flue gas treatment capacity at the kiln tail of a 5000t/d cement production line is about 1 million cubic meters per hour, and the flue gas treatment capacity at the kiln tail of a 10000t/d cement production line is about 1.72 million cubic meters per hour. The bag filter has achieved a breakthrough in adapting to high dust concentrations, and can directly process gases with dust content up to 1400g/m3, which is tens of times higher than before, and can meet emission standards.
Overall principle of bag filter:
(1) Determine the required dust removal efficiency and emission concentration in accordance with relevant emission standards, indoor hygiene standards, and practical possibilities.
(2) Determine the flow rate, required filtration area, filter material, and dust cleaning method of the flue gas in the dust removal equipment based on the characteristics of the dust (dust content, particle size, viscosity, etc.).
(3) Determine the structural form, material selection, and main measures for ash transportation and discharge of the equipment based on the characteristics of the flue gas (temperature, humidity, dew point, pressure, etc.).
(4) Considering the possibility of manufacturing, transportation, and on-site construction, the structure and main components of the equipment require a dismantling plan for large bag filters. The main technical requirements and construction installation procedures for the main components should be clearly stated, and the construction and installation quality should be ensured.
(5) Under the condition of meeting production requirements, it is necessary to invest as little equipment as possible, have low operating costs, and save energy. The main equipment of the dust collector should also be operated, configured reasonably, and maintained conveniently.
