The purpose of large-scale air separation unit is to be used in metallurgy, petrochemical, coal chemical and other industries, as a key unit to provide oxygen, nitrogen, argon for the production process.
Chemical industry has the characteristics of large scale, long industrial chain and so on. It is the basic industry and an important part of Chinese national economy. In recent years, environmental protection has been paid more and more attention, and the green development of chemical industry is also very important. In addition, the chemical industry in the industrial integration, scientific and technological innovation is also in constant efforts to advance. DEAR air separation helps the chemical industry to transform and upgrade to be environmental-friendly. DEAR’s large-scale air separation plant KDON (Ar) - 18000 / 36000-600 can use ultra-low pressure discharge energy-saving air separation technology patent, which can reduce the energy consumption of equipment operation by 5% - 15% and save a lot of production costs.
The metallurgical industry has its unique industry characteristics and high requirements for oxygen purity. DEAR air separation has cooperated with domestic and foreign metallurgical industry customers in many projects, has rich project experience, and has continuously invested funds to develop energy-saving and intelligent air separation plant. KDON-10000/10000 is highly praised by customers for its high efficiency and stable operation.
In order to reduce the air temperature in the low temperature air separation unit, various heat exchange equipment are needed for cold and heat exchange in various air separation systems, such as nitrogen water precooler, switching heat exchanger, main heat exchanger, condensing evaporator, subcooler, liquefier, vaporizer, electric heater, etc. These heat exchange equipments are installed in each system of the air separation unit, which are necessary for air liquefaction and gas separation.
According to the principle of heat transfer, the heat exchanger of air separation unit can be divided into three types:
1. Dividing wall type: the cold and hot fluid is separated by the heat transfer wall, the medium does not directly contact in the heat transfer process, and the hot fluid transfers heat to the cold fluid through the heat transfer wall. For example, tube heat exchanger and plate heat exchanger.
2. Heat storage type: the cold and hot fluid alternately flows through the solid
Temperature difference is the power of heat transfer. As long as there is temperature difference between two materials, they will carry out the heat or cold transfer spontaneously. The heat is always transferred from the fluid with higher temperature to the lower temperature fluid.
Although the heat transfer process of various heat exchangers is not identical, the heat transfer law is basically the same.
The following is an example of the most widely used dividing wall heat exchanger: heat is transferred from hot fluid to cold fluid through the wall and flows in the opposite direction. The whole heat transfer process is divided into three stages.
In the first stage, convection heat transfer: the heat flow body transmits heat to the wall surface. This process not only has heat transfer caused by the relative displacement of each part of the fluid, but also has heat conduction in the fluid, which is the comprehensive function of convection and heat conduction.
In the second