Luobo Nuannan believes that, 1. Cryogenic method
The cryogenic method first compresses, cools and liquefies the air, taking advantage of the difference in the boiling points of the oxygen and nitrogen components. (The boiling point of oxygen is 90 K and the boiling point of nitrogen is 77 K under atmospheric pressure). The gas and liquid are contacted on the distillation tray for mass and heat exchange. The oxygen component with high boiling point is continuously condensed from the vapor into liquid. The nitrogen component at the boiling point is continuously transferred into the steam, so that the nitrogen content in the rising steam continues to increase, while the oxygen content in the downstream liquid becomes higher and higher, thus separating oxygen and nitrogen. This is air distillation. Whether it is air liquefaction or distillation, this method is performed at a temperature below 120 K, so it is also called low-temperature air separation.
The cryogenic oxygen generator is characterized by large production capacity and high oxygen purity (greater than 99.6 O2), which has advantages in large and extra-large oxygen use situations. In most cases, oxygen is produced by cryogenic methods. Traditional cryogenic oxygen production equipment has the advantages of mature technology, stable operation, and high reliability, but it also has shortcomings such as high investment, high operating costs, and potential explosion hazards.
2. Pressure swing adsorption method
The pressure swing adsorption method is the VPSA method. Its basic principle is based on the molecular sieve's selective adsorption of oxygen and nitrogen components in the air. The intermediate oxygen and nitrogen are separated to obtain oxygen. When the air is compressed and passes through the molecular sieve adsorption layer of the adsorption tower, nitrogen molecules are preferentially adsorbed, and oxygen molecules
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remain in the gas phase and pass through the adsorption bed. Become product oxygen. When the nitrogen adsorption in the adsorbent layer reaches relative saturation, use decompression or vacuuming to desorb the nitrogen molecules adsorbed on the surface of the adsorbent molecules and send them out of the boundary area for emptying, so that the adsorbent can be desorbed and resume its original adsorption. To prepare for the next cycle of adsorption oxygen production, two or more (including two) adsorption towers can be continuously circulated to achieve the purpose of continuous oxygen production.
In the past 10 years, pressure swing adsorption oxygen production equipment has developed rapidly. It is a novel oxygen production method. It has great advantages and competitiveness in flexible and changeable oxygen use situations. Rapidly spread. The characteristics of PSA oxygen generator are simple process flow, low investment, low energy consumption, adjustable gas product output and purity, and good flexibility. However, it has shortcomings such as single product, low concentration, and low reliability, so it is suitable for oxygen purity. Below 95, in small and medium-sized oxygen-using occasions and in oxygen-rich copper smelting.
3. Membrane separation method
With the development of synthetic polymer membranes, high-tech technology using membrane methods to separate substances has developed rapidly, and its application scope has become wider and wider. The application in food processing and fermentation broth extraction is particularly valued internationally.
The organic vapor membrane recovery system mainly uses "reverse" selective polymer composite membrane. Under a certain penetration driving force, according to the difference in the dissolution and diffusion properties of different gas molecules in the membrane, condensable organic vapors (such as vinyl chloride, ethylene, heavy hydrocarbons, etc.) and non-condensable gases (such as hydrogen, nitrogen, etc.) Compared with methane, etc.), it is preferentially adsorbed and penetrated, thereby achieving the purpose of separation
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. In industrial applications, five common membrane separation methods include electrodialysis, microfiltration, ultrafiltration, reverse osmosis and nanofiltration.
Applying membrane separation has a series of advantages! (1) The purpose of separation and concentration can be achieved without heating, and it is suitable for food production that is not affected by heat and oxygen; (2) The process is simple and only requires pressurization, transportation, circulation and other processes; (3) When water is separated, it is concentrated There is no change in the physical phase, and the energy loss is less. The simple operation and production cost are lower than the evaporation method and the freezing method, and the equipment is easy to install; (4) It can solve the problem of recovering trace components in dilute solutions and concentrating low-concentration solutions; (5) Substance It only moves within mm and performs short-distance separation, and the substances will not change due to movement; (6) Applying membranes to separate substances consumes less energy. Especially in situations where energy is lacking or energy prices are high, the membrane separation method is more attractive. force. --From the most reliable part-time job platform for college students, Luobo Part-time Job! ! !