Overview
    As metallurgy, chemical industry is developing rapidly, ASU's very large quantities. More new technology in an air separation plant in the application so that the customers face a wide range of choices for how to choose their own air separation plant is very important.
    ASU by major users to points, can be divided into metallurgical and chemical-type. According to the process, is more popular outside the compression process in the compression process with the two types.
    Now, the new domestic air can be divided into sub-item within the compression and compression of the two processes.
    1, what is meant by the compression process, in the compression process
    The compression process is the low-pressure air separation plant production of oxygen, the oxygen and pressurized to press for a total of pressure to users, also known as conventional air separation.
    In the compression process is the abolition of oxygen compressor, air separation equipment directly from the segregation of the tower to produce a high-pressure oxygen supply users.
    The main difference between the two is that the product is the oxygen of oxygen pressure in the cold by liquid oxygen inside the pressurized liquid oxygen pump to achieve, high-pressure liquid oxygen in the plate-fin heat exchanger to heat and high pressure air to the exchange of heat of vaporization rehabilitation.
    Compared with the compression process, the compression process within the major technological changes in two parts: the distillation and heat transfer. The compression process an air separation from the distillation tower is the direct result of low pressure oxygen, the main heat exchanger to heat the cold-box, and the compression process an air separation from the distillation tower is the main condensate evaporator from liquid oxygen and liquid from the Pressure needed to pump oxygen pressure, and then by a high-pressure air and liquid oxygen heat exchanger to vaporize the cold box as the product gas. Can be a simple view, within the compression process is used with liquid oxygen pump air pressure machine to replace the compression process, the oxygen compressor.
    Relatively speaking, within the compression process is a new technology, but also is relatively new so-called domestic industry, the air separation. Like many new technologies, in the compression process an air separation plant as a technology was first developed in the overseas as early as the 1980s there will be a compression process within the air separation equipment, such as China from the 1980s German company Linde Sinopec Zhenhai the introduction of the 28000 m3 / h air separation plant on the use of the technology within the compression process.
    In the compression process the application of technology in foreign 

    countries mainly in the following three factors:
    (1) security considerations, in theory, be safe within the compression process some of the air, the security sub-sector demand is very high.
    (2) used in the compression process with the required liquid oxygen pump air pressure machine corresponding to a much lower cost; oxygen compressor in the design and manufacture of the need to consider more factors of security, the price is very expensive.
    (3) in the compression process for pipeline gas supply, the foreign gas companies operating in the gas business at the same time, often selling large quantities of liquid products.
    2, the compression process and the compression process investment compared
    2.1 The cost of the investment
    From the cost of the investment, within the compression process and the compression process in the following different part of the cost of the investment.
    2.1.1 part of the compressor
    Mainly refers to the compression process of adding liquid oxygen pump and air pressure machine, compressed oxygen compressor compared.
    Abroad, is the first choice of the compression process an air separation plant. Because the oxygen compressor abroad is very expensive, such as compression process in need of oxygen compressor turbine, the average domestic prices of three to four times, and the compression process within the required air pressure machine is the price of domestic oxygen Permeability of 1.5 times.
    In China, the opposite situation. Compression process, the oxygen can be fully realized through domestic and quality and cheap, good safety performance. And the use of the compression process, the domestic unit can not fully meet the requirements. The air pressure requirements for general import unit, so that the use of the compression process an air separation plant on the cost high.
    2.1.2 of the heat exchanger
    In the compression process in the air at high pressure to use the plate-fin heat exchanger, which will involve changes to the investment cost, domestically produced high-pressure heat exchangers in the quality is quite reliable. However, almost all on the air compression process within the sub-item of the users of domestic products is not assured, so in this part of a lot of added cost, which will increase about 20 percent.
    2.1.3 expander part
    In the compression process in the use of pressure expander, if the choice of imported products, often not prepared for, the general needs of Daiqi rotor, including spare parts and the selection of domestic units, will be used by a one-way, so the cost of imported products More than 30 percent higher.
    The compression process used for expansion of low pressure, local units can achieve the performance of imported products.
    2.1.4 part of the valve
    Compressed air separation processes within some of the flow of high pressure in the road, corresponding to the requirements of the valve also relatively high, so this part will be some increase in costs. Generally, a set of compression process an air separation plant than the total price of the same compression process an air separation plant to the high 10 percent.
    3, running costs
    That is the main operating costs: energy consumption, spare parts and maintenance costs, operation and maintenance personnel expenses.
    3.1 The energy consumption
    ASU in the liquid products (liquid oxygen and liquid nitrogen and liquid argon total) products accounted for the proportion of oxygen gas to the impact of energy consumption is significant. Generally it that the ratio of about 8 percent is a threshold below which selected in proportion to the compression process, if this ratio higher than that used in the compression process can be relatively good.
    3.2 Spare parts and maintenance costs and personnel expenses
    Compared with the compression process, in the compression process an air separation plant due to imports of equipment and other components unit more, the corresponding spare parts and maintenance costs will be higher.
    4, safety and reliability
    Finally there is still a very important aspect of that security and reliability, this is the most fundamental, ranging from influence the normal operation of production equipment, weight affected the success of the overall investment.
    As mentioned above, in theory, the compression process an air separation plant some of the safe, relatively speaking, compression process an air separation plant security risks mainly in the main condensate evaporator, the accumulation of hydrocarbons in the liquid oxygen and oxygen pressure turbine Machine. The former can be online monitoring and regular security liquid oxygen emissions to solve the problem, the latter of domestic oxygen permeability of the technology has been through, the absolute guarantee security, has never been to a vicious explosion and other accidents. It can be said that, after many years of technological development, air-compression process, the security is no problem.
    ASU on the reliability of the operation related to the quality of equipment, such as operation of the various factors. The compression process an air separation technology is mature, users are also skilled operation, high reliability. In the compression process to be relatively complex, automated control of the more demanding.
    At present it can be said that the compression process an air separation plant is completely meet the domestic needs. And the compression process an air separation plant, the present circumstances, apply to specific users.
    5, the metallurgical industry on the choice of an air separation plant 
    The metallurgical industry on the use of oxygen pressure in the request are usually between 2.0 ~ 3.0 MPa, then the compression process an air separation plant or outside the compression process an air separation plant can achieve.
    At present, domestic manufacturers of compression process an air separation plant in a typical air into the expansion process is under the tower of the process. Its characteristics are: First, more suitable for the production of more liquid, the Argon is the high rate of extraction.
    Now ordered all domestic metallurgical industry in the compression process an air separation plant users a choice in this process, these users have the same needs: the need for a large number of liquid products to meet the production of the gas sales business.
    At the same time, this process Another advantage of an area of less raw materials of air compressors and air pressure can be combined into one machine.
    Not considered part of the gas sales business, then the choice of conventional compression process an air separation plant on the very reasonable.
    6, the chemical industry on the choice of an air separation plant
Chemical (Sinopec), industry-to-use oxygen pressure on the request of the general higher than the steel-making more generally in the 4.0 MPa ~ 9.0MPa above, the oxygen is also very large scale, at every turn, "30000" above. As a result, the use of the compression process an air separation plant is the only choice. Moreover, because of the chemical air separation plant in the product structure is usually more complicated and require a variety of pressure at the same time the production levels of oxygen, nitrogen products, which requires specific requirements for a variety of programmes, such as a single-or double-pump Pump, compression, is the use of air circulation or nitrogen cycle, the best programmes must follow the one-time investment costs and long-term cost of running the best combination of principle.
    Of course, if the customer on the request of an air separation plant is not complex, similar to the type metallurgical air separation plant, in accordance with the usual compression process within or outside compression process can be considered.
    7, the conclusion
    At present, the compression process is already fully-fledged air separation process, the air separation of domestic manufacturers have full control of the relevant technology, from air separation equipment supplier sets the angle of absolutely no problem. However, China's turbine machinery manufacturing industries and foreign counterparts is still a large gap, in such circumstances, it can be said in a key part of the machinery on the domestic manufacturing sector has not been doing a good job in the compression process an air separation plant Localization of the complete work.
    Outside as the compression process after years of development, technology is ripe for the air separation process, the more applicable to the majority of the demand.
    Users in new air separation projects, different air separation equipment manufacturers recommended by the programme has its own interests to consider, multi-user should be inspected, and more technical exchanges and explore whether the choice of the compression process or the compression process Must be in accordance with their needs and domestic design and manufacture of the actual situation to do the decision-making.