As an efficient equipment for removing particulate matter, bag filter can completely reduce the emission of smoke and dust, and it is an important technical equipment to solve the emission of smoke and dust in China. Take the cement industry as an example. At present, all domestic cement enterprises use bag filters, and each new dry cement kiln can reach the dust emission limit specified in GB49 15-20 13, that is, 0. 15~0.30 kg per ton of clinker. According to the data of the National Bureau of Statistics, the particulate emission of China cement industry in 20 12 was 3.68 million tons, but it should be 230,000 ~ 460,000 tons according to the new national standard, which is technically feasible. If 50% of the country's coal-fired boilers also use bag filters, the power industry can reduce dust emissions by more than 6.5438+0.2 million tons per year, which means that the bag filter technology can fully support stricter standards, and the emission limit can be further reduced, which will play a huge role in reducing particulate emissions. Many domestic application cases show that the bag filter can achieve stricter particle emission standards without increasing the cost and operating expenses. As long as the design, manufacture, installation and operation are carried out in strict accordance with the existing standards and specifications, good results can be achieved.
Bag dust removal equipment technology
The design and selection of bag filter changed from high filtration rate, high resistance and short service life to high efficiency, low resistance and long service life, and pursued the excellent comprehensive effect of energy saving and emission reduction, which was embodied in the rapid popularization and application of bag filter in blast furnace gas dry dust removal, boiler flue gas dust removal in coal-fired power plants, cement kiln head and kiln tail flue gas dust removal, and waste incineration flue gas purification, and achieved remarkable results;
In the dust control project, the emission concentration is lower than10 mg/nm3; The system resistance is lower than1000 pa; ; The average cleaning effect of filter bag is good; The life of diaphragm of pulse valve is greatly prolonged, and it is a common phenomenon to use it for 3 ~ 5 years. It is common to have a service life of more than 4 years. Pulse bag dust removal technology has achieved good results in various industrial fields. The performance of pulse valve, the key component, has surpassed that of foreign products in some aspects, thus achieving the rapid and large-scale bag-type dust removal equipment. Bag dust removal equipment used in steel, cement, electric power and other industries. The flue gas treatment capacity of many single machines exceeds 2 million m3/h, and the filtration area exceeds tens of thousands of square meters. Among them, the maximum flue gas treatment capacity of single bag dust collector in power industry exceeds 3 million m3/h, and the filtration area is mostly 4 million. Of course, many new technologies have been injected into large-scale equipment, which has made remarkable progress in air distribution, air flow distribution and body structure of bag filter. The manufacturing equipment and technology of large-scale bag filter in China have also made great progress, the scale is getting bigger and bigger, and the equipment is becoming more and more specialized. Many bag filter processing enterprises have built CNC machining centers, which greatly improve the manufacturing accuracy. Special equipment and special processing machinery are widely used in bag dust removal industry. Laser cutting is used to produce decorative panels, and multi-spot welding machines are widely used to process bag cages. In recent years, there is no country in the world where the bag filter processing enterprises have developed so rapidly and professionally as China, which has also promoted the export and outsourcing of bag filters.
The most remarkable sign of bag-type dust removal technology progress is the large-scale equipment, but the large-scale equipment is not a simple increase in volume, it involves the modular design, manufacture and installation of equipment, air distribution and adjustment, the reliability of long-term operation of dust removal system and the long life of filter bags. With the installed capacity of China's thermal power industry changing from 100MW, 200MW and 600MW to 1000 MW; A single production line in cement industry ranges from 3000t/d, 4000t/d and 5000t/d to 12000t/d; The volume of single blast furnace in iron and steel industry ranges from 700m3, 1000m3 and 2000m3 to 4000~5300m3. Our country's scientific and technological personnel give full play to their intelligence, constantly develop and follow up quickly, which makes our country's bag dust collector rapidly large-scale, and the treated air volume is increased from the original100000 m3/h to 6.5438+00000 m3/h, from 2 million m3/h to more than 3 million m3/h; The filtration area ranges from 2000m2, 1000 m2 and 20000 m2 to 50000m2 ~ 60000m2; In the process of large bag dust removal, the equipment resistance is greatly reduced, from 1500 ~ 1800 Pa to 1200Pa or even below 1000Pa. The filtration efficiency is steadily and effectively improved, and the dust emission concentration is below 10mg/Nm3, and the dust emission concentration of domestic waste incineration industry and blast furnace gas purification is generally below 10mg/Nm3. It is precisely because the large-scale bag dust removal equipment has provided great support for China's industrial energy conservation and emission reduction at all stages of industrial development that China's economic development and environmental governance have made great achievements at the same time. It can be said that without the rapid development of bag dust removal technology, the atmospheric environment in China would be worse than it is now. As we all know, equipment amplification in any industry is not a simple amplification, but requires a lot of corresponding technological progress, and most of them are based on some key technological breakthroughs. Large-scale bag filter is developed on the basis of major breakthroughs in filter material research and development, filter bag manufacturing technology, ash cleaning technology and equipment, air distribution technology, whole machine processing and manufacturing and equipment technology. Like large-scale equipment in steel, metallurgy, cement and electric power industries, large-scale bag dust removal equipment is also based on the improvement of China's overall industrial level; At the same time, it also promoted the overall level of China industry. The whole production line of cement industry, including dust removal equipment, has been widely promoted and built abroad.
1, cement industry
Cement industry is one of the industries with serious pollution. There used to be a thick layer of cement dust around the cement plant 1 ~ 2 km. In 2004, when a 5000t/d cement production line was rebuilt in a cement plant in Guangzhou, domestic scientists and technicians developed a large-scale low-resistance long bag on-line off-line pulse dust collector based on decades of dust removal experience and foreign environmental protection design requirements. The treated air volume is 654.38+100,000 m3/h, the flue gas temperature is 240℃, the service life of the filter bag reaches 6 years, and the running resistance of the equipment is lower than 1200Pa. It meets the strict international environmental protection requirements, not only meets the requirements of this production line, but also clears the major environmental protection obstacles for the technical popularization of the production line from 5000t/d to 12000t/d in China. In recent years, the whole process line of cement industry adopts bag dust removal technology, especially the kiln head and kiln tail are changed from electrostatic precipitator to bag dust collector, which has changed the messy scene in the past, and many cement plants have become garden-style cleaning plants.
2. Iron and steel industry
The steel industry is also one of the industries with serious pollution. The typical representative of bag dust removal technology progress in iron and steel industry is blast furnace gas dust removal and purification. A large amount of blast furnace gas will be produced in the process of ironmaking, and the blast furnace above 5000m3 will produce about 900,000m3 blast furnace gas per hour. Blast furnace gas contains a large amount of carbon monoxide and a small amount of hydrogen, which is a valuable energy source. However, crude gas contains a lot of dust and must be purified before it can be used. CO and hydrogen are explosive, and CO is highly toxic, so the purification process is more dangerous. The traditional wet dust removal method of blast furnace gas is venturi tube, which not only has large heat loss and low purification efficiency, but also consumes a lot of water resources and produces polluted water. In 1990s, China scientific and technical personnel took the lead in developing the research on dust removal and purification of blast furnace gas bag in the world, and achieved success. The bag dust removal technology for blast furnace gas purification developed in China adopts inert gas dust removal and ash conveying technology, which fundamentally avoids the danger of combustion and explosion in dry purification of blast furnace gas. The technology has high purification efficiency and stability, and the dust content of the purified gas is less than 5mg/m3, which fundamentally removes the gas sludge and avoids huge sewage treatment facilities and serious pollution to the environment. Make full use of the pressure energy and heat energy of blast furnace gas, the residual pressure power generation can be improved by 30% ~ 50%, the energy can be saved by 40% ~ 50%, the water can be saved by 80% ~ 90% and the investment can be saved by 30% ~ 90%. This technology is internationally leading.
3. Power industry
Many national "Tenth Five-Year Plan" and "863" projects completed by many units in China, such as changing the electrostatic precipitator of 20MW units in Jiaozuo Power Plant to bag precipitator, changing the electrostatic precipitator of 600MW units in Shazhou Power Plant in Zhangjiagang to bag precipitator, changing the electrostatic precipitator of Baosteel's own power plant to bag precipitator, and changing the electrostatic precipitator of 30MW×4 units in Waigaoqiao, Shanghai to bag precipitator, are typical applications of bag precipitator technology in coal-fired power plants, which shows that the thermal power industry can effectively control dust emission and achieve national and local emission below 30. The system resistance of these projects is lower than 1200Pa, and some of them are lower than 800Pa. The smoke emission concentration is less than 20mg/m3, and the service life of the filter bag is as long as 5 years. The air volume of bag dust removal treatment for 600MW unit is 3.6 million m3/h, and the filter material reaches 60,000 m2.
Special fiber and filter material for bag filter
Fiber and filter material are the core materials of bag filter. In recent years, the remarkable technological progress of bag dust removal industry is reflected in solving the problem that the industry has long relied on imported high-temperature fibers (such as aramid fiber, polyphenylene sulfide, polyimide, polytetrafluoroethylene and other basic raw materials needed to produce filter bags), ensuring the great development of filter material technology in bag dust removal industry in recent years, supporting the national industry and solving the urgent needs in China. With the country's unprecedented attention to environmental protection, the government and private capital have invested more and more in environmental protection, and the environmental protection industry has shown a rapid development trend. Bag filter is widely used in steel industry, cement industry, power industry, chemical industry and waste incineration industry, which also brings a very good opportunity for the development of filter media industry in China.
With the wide use of bag filter in various industries, the recycling of waste filter bags has attracted the attention of all parties. At present, the recycling technology of waste filter bags such as pure aramid fiber, PPS, polyimide and PTFE in China is becoming more and more mature, and the collection, transportation and comprehensive utilization system is basically established, which can basically recycle waste filter bags. Several chain companies have been established nationwide to recycle waste filter bags. The chemical recovery of PPS and PTFE composite filter media has been completed in the laboratory, and the pilot work is under way.