The application of deep cooling technology in the design of air separation equipment
Abstract: With the rapid development of the national economy and the continuous improvement of the level of science and technology, a variety of new types of air separation equipment continues to appear, as the earliest emergence of the technology of air separation technology, deep cooling technology has been widely used in its development. The article mainly focuses on the concept of deep cooling technology, the meaning of air separation equipment and the application of deep cooling technology in the design of air separation equipment is briefly analyzed and explored.
Keywords: deep cooling technology; air separation equipment; design; application; concept
CCTS: TQ116.11 Literature ID: A Article No.: 1006-8937(2014)23-0063-02
The air separation technology originated in 1985 with the first set of air separation equipment created by German Karl K. Linde in 1903. Linde professor created the first set of air liquefaction equipment and 10 m3 / h (oxygen) air separation equipment, in its more than 100 years of development, with the continuous development of new technologies, air separation equipment and technology has been a great development, deep cooling separation technology in the air separation of the earliest one of the technology, by the people's continuous research and innovation, in the practice of industrial production and equipment renewal more and more mature, the scope of application in the development of the national economy and also in the development of the national economy and the development of the air separation technology. The scope of application in the development of the national economy is also more extensive.
1 deep cooling technology concept
Deep cooling technology refers to the use of refrigerant media as a cooling medium, the quenching of metal materials after the cooling process continues, to reach a temperature far below room temperature (-196 ℃), and thus realize the performance of the metal material to send the purpose. In recent years, with the continuous development of the design of air separation equipment, as a new process technology of metal workpiece performance sending, deep cooling technology is the most effective and economical and practical technology at this stage.
In the deep cooling process, a large number of residual austenite in the metal is converted to martensite form, especially from -196 ℃ to room temperature in the process of supersaturated sub-stable martensite degree of supersaturation will decline, precipitation dispersion, ultrafine carbide its relationship with the matrix to maintain the **** grid, the current is only 20 ~ 60 A, the production of this phenomenon can be reduced to reduce the martensitic lattice aberration, reduce the microscopic stress, the plastic deformation of the material in the fine carbides. In the plastic deformation of the material fine dispersed carbide can cause obstruction to the dislocation movement, and then play the role of matrix organization strengthening. At the same time, the precipitation of ultra-fine carbide particles to be uniformly distributed in the martensitic matrix, the role of the grain boundary embrittlement is effectively attenuated, refinement of the matrix organization not only impurity elements in the degree of aggregation at the grain boundary is effectively attenuated, but also give full play to the role of the grain boundary reinforcement, which greatly improves the performance of the mold and die to improve its hardness, impact toughness and abrasion resistance. The application of deep cooling technology is not only embodied in the work surface, but also in the workpiece internal penetration, showing the holistic effect, based on which the workpiece can be remolded, multiple use. In terms of the workpiece, the application of deep cooling technology can also effectively reduce the quenching stress and play a role in enhancing the dimensional stability.
2 The meaning of air separation equipment
With the rapid development of social and economic and scientific and technological progress, in the development of air separation research and other industries, the development of its equipment has shown a trend of large-scale, air separation equipment supporting the requirements are also increasingly high. At this stage, in the independent development of air separation equipment in China's level level has reached 60,000 levels, and the world's advanced level is very close. 2002, Hangzhou oxygen 30,000 levels of domestic air separation equipment in the successful operation of the Baosteel Group, so that the competitiveness of China's air separation equipment has been greatly enhanced, and prompted the success of domestic large-scale air separation equipment to a wide range of the domestic market to occupy.
3 deep cooling technology in the design of air separation equipment
Air deep cooling separation process is the use of multi-tower low-temperature distillation, from the compressed air to produce high-purity oxygen, nitrogen and other products. At present, there are two main forms of existence in the design of air separation equipment, the first is room temperature air separation equipment, this equipment is mainly in the state of room temperature and non-low temperature, this room temperature air separation equipment can be divided into two different forms: variable pressure adsorption separation and membrane separation. Here to be analyzed is another form of air separation equipment design, deep cold air separation, this equipment is mainly used in the case of very low temperature. In the 1950s, in order to enhance our national defense force, to meet the needs of national defense, our deep cold air separation technology and equipment are imported from the Soviet Union and imitation, at that time the imitation of the enterprise for the Hangzhou Iron Works. It was only around 1953 that we successfully copied our own deep-cooled air separation equipment. Until now, China's air separation technology and equipment manufacturing level has been greatly developed, and for the growth of the national economy to contribute to its own strength. At present, the deep-cooled air separation technology is mainly used in the following aspects.
3.1 Compressed air purification components
The main components of compressed air purification components are high-efficiency degreaser, refrigerated dryer, precision filter and activity filter. First of all, the air should be compressed in the air compressor, and then work in the air buffer tank, and then through the high-efficiency degreaser to effectively remove most of the impurities, impurities mainly include oil, water and dust, etc., in the further removal of water can be used in the refrigerated dryer, and then again for the removal of oil, dust can be used in the implementation of the operation of precision filters, and finally use the activated carbon filters for deeper de-oil work. Oil work.
3.2 Air buffer tank
The main components of the air buffer tank assembly are air buffer tank and attached valves and instruments. Air buffer tank in the air separation equipment design plays a major role in the buffer, the airflow pulsation to play an effective reduction. In turn, the system pressure fluctuations are reduced, so that the compressed air can be smoothly in the compressed air purification components through, maximize the You, water and other debris for effective exclusion. At the same time, in the adsorption tower work switching process, can also help the oxygen and nitrogen separation system in a very small amount of time to get a large amount of compressed air needed, the application of this technology can help the adsorption tower pressure to quickly rise and reach the working pressure, but also to ensure the reliability and stability of mechanical equipment operation.
3.3 Oxygen-Nitrogen Separation System
The main components that make up the oxygen-nitrogen separation system are the adsorption tower, compression device, auxiliary valves and instrumentation and electrical appliances. Selection of composite bed structure design of the adsorption tower, mainly divided into two towers: tower A and tower B, the imported carbon molecular sieve filling into the tower (in order to improve the uniformity of the carbon molecular sieve filling can be used to stretch the torsion vibration filling mode of operation). Clean compressed air to be the first from the entrance end of the A tower under the action of carbon molecular sieve flow to the exit end, this time by its adsorption of the main components of oxygen, carbon dioxide and water, in the adsorption of the tower exit end of the outflow of nitrogen only products. After the continuous passage of time, when the carbon molecular sieve adsorption in the A tower to reach saturation before there will be automatic adsorption to stop the phenomenon, in the B tower in the inflow of clean compressed air in the oxygen production of nitrogen, and the regeneration of molecular sieve for the A tower. Through the adsorption tower quickly reduced to atmospheric pressure desorption of oxygen, carbon dioxide, water to realize the regeneration of molecular sieve. In the A, B tower alternating adsorption tower regeneration, not only can promote the completion of oxygen and nitrogen separation, but also can continue to produce nitrogen.
3.4 Oxygen and nitrogen buffer system
The main components of the oxygen and nitrogen buffer system components are nitrogen buffer tank, precision filters, flow meters, regulators, venting components, etc. The nitrogen buffer tank is mainly used to equalize the pressure and purity of nitrogen separated from the nitrogen-oxygen separation system, to ensure the stability of the nitrogen and guarantee the continuous supply. At the same time, in the adsorption tower switching work, some of its own gas adsorption tower back to the charging operation, this way can effectively play a role in enhancing the adsorption tower pressure, but also play an effective protection of the bed, in the work of the air separation equipment can also play a great role in the protection. Finally filtered again, mainly using precision filters to work, which can maximize the quality of nitrogen.
As a traditional way of nitrogen production, deep cooling air separation nitrogen production has been developed for decades. This method mainly uses air as the raw material, and in order to liquefy the air into liquid air, it must be strictly compressed, purified, and heat exchanged. Liquid air is mainly composed of a mixture of two parts: liquid oxygen and liquid nitrogen, through the different boiling points of the two liquid air distillation, the two will be effectively separated and access to nitrogen. In the whole work operation deep cold air separation nitrogen equipment and process is very complicated, need to occupy a wide range of land area, infrastructure costs are very high, the speed of gas generation is very slow, in the installation process, has a high demand and long working period. Deep-cooled air separation equipment, installation and grass-roots construction and other factors for a comprehensive analysis, when the equipment is less than 3,500 N m3 / h, the same specifications of the PSA plant and deep-cooled air separation plant in the cost of investment compared to the lower between 20% and 50%. In terms of economic adaptation, deep-cooled air separation nitrogen device is not adapted to medium and small-scale industrial nitrogen production, mainly adapted to larger-scale industrial nitrogen production.
4 Conclusion
In summary, with the continuous improvement of science and technology, China's air separation equipment and technology is increasingly large-scale, specialization, scale of the development trend. Deep cooling technology as the most important separation technology of air separation, in order to ensure that the maximization of the interests of enterprises on the basis of deep cooling technology to effectively reduce the amount of energy consumption, is the main task of air separation work.
References:
[1] Ye Binan. Hangzhou oxygen application of new technology to develop a series of new products[J]. Deep Cold Technology, 1996,(4).
[2] Jiang Runmin. Modular design and manufacture of air separation equipment and cryogenic liquefaction equipment[J]. Deep Cooling Technology, 1997,(4).
[3] Helmut Springmann, Mao Jie. Status and prospects of air separation equipment[J]. Deep Cooling Technology, 1974, (3).
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