Views: 0 Author: Site Editor Publish Time: 2022-05-04 Origin: Site
The production scale of China's air separation equipment has changed from the early stage, which can only produce 20m3 / h (oxygen) oxygen generator. It has developed to the capacity of producing 20000 m3 / h, 30000 m3 / h, 50000 m3 / h and 60000m3 / h large-scale air separation equipment, and has completed the scientific research stage and is about to manufacture 80000m3 / h ultra large-scale air separation equipment.
Air separation plant is a large complex system, which is mainly composed of the following subsystems: power system, purification system, refrigeration system, heat exchange system, distillation system, product conveying system, liquid storage system and control system.
It mainly refers to the feed air compressor. Air separation equipment separates air at low temperature to obtain oxygen, nitrogen and other products, which is essentially completed through energy conversion. The energy of the device is mainly input by the feed air compressor. Accordingly, most of the total energy consumption required for air separation is the energy consumption of feed air compressor.
It is composed of air precooling system (air cooling system) and molecular sieve purification system (purification system). The compressed raw air has a high temperature. The air precooling system reduces the temperature of the air through contact heat exchange, and can wash the acidic substances and other harmful impurities. The molecular sieve purification system further removes moisture, carbon dioxide, acetylene, propylene, propane, nitrous oxide and other substances harmful to the operation of the air separation unit.
Refrigeration system: the air separation plant is cooled by expansion, and the refrigeration of the whole air separation plant strictly follows the classical refrigeration cycle. However, the commonly mentioned air separation refrigeration equipment mainly refers to the expander.
Heat exchange system
The heat balance of air separation unit is completed through refrigeration system and heat exchange system. With the development of technology, aluminum plate fin heat exchangers are mainly used in heat exchangers.
As the core of air separation equipment, it is an important equipment to realize low-temperature separation. High and low pressure two-stage distillation is usually adopted. It is mainly composed of low pressure tower, medium pressure tower and condensing evaporator.
Product conveying system
The oxygen and nitrogen produced by the air separation unit need a certain pressure to meet the use of subsequent systems. As long as it is composed of oxygen compressors and nitrogen compressors of different specifications.
Liquid storage system
The air separation unit can produce certain products such as liquid oxygen and liquid nitrogen, which enter the liquid storage system for use when necessary. As long as it is composed of storage tanks of different specifications, cryogenic liquid pumps and vaporizers.
The large-scale air separation equipment adopts computer distributed control system, which can realize automatic control.
In terms of process flow, the air separation plant can be divided into five basic systems:
Impurity purification system
It is mainly through air filter, Molecular Sieve Absorber and other devices to purify the mechanical impurities, moisture, carbon dioxide, acetylene, etc. mixed in the air.
Air cooling and liquefaction system
It is mainly composed of air compressor, heat exchanger, expander and air throttle valve, which plays the role of deep freezing of air.
Air distillation system
The main components are distillation tower (upper tower and lower tower), condensation evaporator, subcooler, liquid air and liquid nitrogen throttle valve. It can separate various components in the air.
Heating and purging system
The purification system is regenerated by heating and blowing.
Instrument control system
The whole process is controlled by various instruments.