The method of separating liquid air is an industrial method for preparing oxygen and a physical method. The principle is that the boiling point of nitrogen in air is lower than that of oxygen. The specific steps are as follows: the air in the atmosphere is preliminarily purified to remove impurities such as dust and water vapor, and then compressed to a high pressure state by a compressor.
Cooling by a cooler to liquid state, and performing multistage separation by a separation tower to obtain a high-purity oxygen product.
Membrane separation technology is a selective separation technology that allows molecular mixtures with different particle sizes to pass through a semi-permeable membrane at the molecular level. Semi-permeable membrane is also called separation membrane or filtration membrane, and its wall is covered with micropores. According to the pore size, it can be divided into microfiltration membrane (MF), ultrafiltration membrane (UF), nanofiltration membrane (NF) and reverse osmosis membrane (RO).
Membrane separation technology can be used to separate various liquid and gaseous substances, including water treatment, energy, materials, chemical industry and other fields. In sewage treatment, membrane separation technology can be used to recover useful substances in sewage and purify water quality. In the field of energy, membrane separation technology can be used to separate and purify hydrogen in fuel cells. In the field of materials, membrane separation technology can be used for the synthesis and separation of polymer materials. In the chemical field, membrane separation technology can be used to separate and purify the products in the chemical reaction process.
The advantages of membrane separation technology include high efficiency, energy saving, environmental protection and simple operation. Membrane separation technology can be carried out at room temperature without destroying the chemical properties of substances, and can be used for the separation and purification of various substances. At the same time, membrane separation technology does not need to use a large number of chemical reagents and additives, and will not produce secondary pollution. In addition, membrane separation technology also has the advantages of simple equipment and easy operation and maintenance.
However, membrane separation technology also has some shortcomings, such as short membrane life, need to be replaced regularly, low membrane flux and so on. In addition, the separation effect of membrane separation technology for some specific substances is not ideal and needs to be further improved.
Application of oxygen in life;
1. Health care: Oxygen is one of the most important gases in the medical field, which is widely used to treat various diseases and obstacles, such as asthma and chronic obstructive pulmonary disease (COPD). Oxygen can also be used in surgery to provide patients with adequate oxygen supply.
2. Exercise and fitness: At high altitude or high intensity exercise, people need more oxygen to maintain normal function. In fitness and sports training, oxygen inhalation can improve sports performance and enhance physical fitness and endurance.
3. Industrial production: In the industrial field, oxygen is widely used in cutting, welding, smelting and chemical production. Oxygen can also be used to produce high-purity semiconductor materials such as silicon and germanium.
4. Aerospace: In the aerospace field, oxygen is essential. It is used to provide breathing oxygen for astronauts and fuel for rocket engines.
5. Environmental monitoring: Oxygen is often used for environmental monitoring, especially for water bodies (such as lakes and seawater). The concentration of oxygen can reflect the pollution degree and self-purification ability of water body.
6. Military use: In the military field, oxygen is used to provide breathing oxygen for submarines and fighters and fuel for rocket engines.