In 1940, Charles and Geoffrey hwward first solved the leakage problem of chemical pump with dangerous medium. The solution was to drive the pump with magnetic force. In the next 30 years, the progress of permanent magnet transmission technology is very slow due to the magnetic materials. In 1983, the appearance of high-performance NdFeB permanent magnet material provides the material of key components for the rapid development of magnetic drive pump. In recent years, the permanent magnet drive technology has been extended from pumps to other sealing machinery, focusing on improving the reliability of the equipment, the research of new materials resistant to medium corrosion, fluid technology and the accuracy of manufacturing and assembly. Magnetic pump represents the level of manufacturing technology in a country. In recent years, the magnetic pump in industrial developed countries has made breakthrough progress in efficiency, life, manufacturing cycle, cost, reliability and so on.
The permanent magnet transmission technology is to transfer the power of prime mover to the inner magnetic component on the working shaft through the external magnetic components on the shaft. The inner and outer magnetic components are separated by the isolation cover, so that the working shaft does not need to extend out of the space to be closed, thus canceling the dynamic seal and realizing no sealing and zero leakage. Permanent magnet drive technology is mainly used in the chemical industry, petrochemical industry, medicine, food industry in the pump and compressor, mixer and valve. At present, the traditional mechanical seal widely used in fluid machinery in China has been gradually replaced by permanent magnet drive in these departments abroad.
2. Broaden the application field and improve the technical performance
2.1 magnetic drive is the most effective and safe solution in the field of sealing
Permanent magnet drive, namely permanent magnet coupling, is the safest solution to the harmful, toxic, polluted, dangerous, pure and valuable products and production process for the machinery that needs to be sealed, and its application range is very wide. Most of the liquids in petrochemical, pharmaceutical, film, electroplating, nuclear power and other industries are corrosive, flammable, explosive, toxic and valuable. Leakage will lead to waste of working fluid and environmental pollution; vacuum and semiconductor industry should prevent the invasion of external gas; diet and medicine should ensure the purity and sanitation of the medium. Permanent magnet drive technology has found its application in these fields. British Howard Machinery Development Co., Ltd. (HMD) has been committed to the manufacture of sealless pumps since 1946, and has sold nearly 70000 sets in 37 countries around the world, with an annual sales volume of 28 million pounds. A pharmaceutical factory in the United States has hundreds of centrifugal pumps equipped with mechanical seals to deal with various acids. Due to design problems, these pumps often run dry, and can only be used for 2-3 months. Instead of k1516 series magnetic drive pumps produced by ansimag company, they were put into operation since 1993 (4.8 hours per day, 365 days per year) to 1998. In the container plate plant in the Midwest of the United States, synthetic caustic soda is a great problem for the sealing of rotary vane pumps. Engineers here call these pumps "maintenance of the day in the dark". The ETFE lined unsealed magnetic pump of ansimag company has been installed and has been running for 11 months without shutdown . A large chemical plant in the United States is facing serious difficulties in transporting methanol. Because methanol is inflammable, the temperature is close to boiling at 60 ℃, the flow rate is only 7m3 / h, and the pressure difference is as high as 250m. The solution of the problem depends on dickow magnetic drive multi-stage end suction pump, whose flow rate is 15m3 / h and pressure difference is 400m, which ensures the zero leakage of methanol, ensures the safety of operators and the plant, and solves the problem of conveying bubbles in methanol .
2.2 the technical performance of magnetic pump is developing towards miniaturization and large-scale
In order to meet the needs of domestic and foreign markets, the complete set of equipment in petrochemical companies is developing to large-scale. China must have a batch of refineries with an annual output of 10 million tons and ethylene plants of 1 million tons. Mechanical equipment should meet the requirements of heavy load, long period, low energy consumption and environmental protection. In our country, it is found that the material and process requirements for manufacturing magnetic pump are very high. Even if 11 ~ 13kw medium and small power pump, its reliability manufacturing cost can not be accepted by users. For the high-power pump with strong corrosion resistance, high pressure and high temperature, it is still blank. At present, the development limit of magnetic pump should be described by HMD company's products: flow rate from 1m3 / h to 681m3 / h, pressure difference from 10m to 500m, temperature range from - 100 ℃ to 450 ℃, system pressure from vacuum to 400bar, prime mover power up to 350kW. The micro pump is specially developed for some departments, such as laser cooling, analytical instrument feeding, chemical supplement, bioengineering, cooling cycle, even printer nozzle, etc. Gear pump and motor integrated closed connection, suitable for 24 V, 36 V DC power supply, speed manual automatic control. The minimum flow rate was 10 ml / min and the pressure difference was 7 bar. MD series micro magnetic drive gear pump of Japan iwaki company is used for electroplating and cooling cycle. The flow range is 7.5 ~ 288l / min, and the transmission power is 1 / 25 ~ 1 / 3 HP.
2.3 all kinds of pumps can be transformed into magnetic drive pumps
Centrifugal pump is the leading product of magnetic pump. Although magnetic drive rotary displacement pump has a history of 25 years, only in recent seven or eight years can it have a broad foundation in design and manufacturing level and high torque capacity. The key point is the magnetic drive gear pump and screw pump. The maximum transmission capacity is 400nm, and the power is 150KW when the speed is 3500r / min. Located in the U.S. border, the U.S. gas power plant, the lubrication pump of turbine compressor is the normal rail external gear pump. Due to the high pressure difference, the oil pump is scrapped due to excessive wear every two months, resulting in compressor shutdown. Since 1992, it has been running continuously without any maintenance. TUTHILL, UK, has successfully applied its magnetically driven gear pump as an additive in Scottish's process water system, which replaces screw pump and complies with health and safety regulations.
2.4 magnetic drive compressor