Liquefied air separation FAQ

Expanders in Air Separation Plants

Due to the large demand for cryogenic liquid of the market, and in order to ensure the normal operation of the production line when the air separation plant stops abnormally or the air supply is interrupted due to failure, the air separation users with cryogenic liquid production capacity will maximize the production and storage of liquid products while ensuring that the gas production is not affected, and try their best to improve the production of liquid products.

In order to realize the separation of oxygen and nitrogen in the air separation plant, the first thing is to make the air liquefaction, which must try to reduce the air temperature to the liquefaction temperature. The absolute pressure of the lower tower of the air separation tower is about 0.6MPa. Under this pressure, the temperature at which the air begins to liquefaction is about-172 ℃. Therefore, in order to make the air liquefaction, there must be a cold fluid with lower temperature to cool the air. As we know, the air separation plant is cooled by the inflated low temperature air. If the Air wants to expand, it needs to be compressed first, and the compression needs to consume energy. Air expansion can be through throttling expansion or expansion machine expansion. However, the temperature drop of this kind of expansion is limited. For high pressure air of 20MPa ℃ and 30℃, the temperature drop is only 32℃ when throttling to 0.1MPa. In the turbine expander, the maximum temperat...

If the passing capacity of the liquid-air regulating valve selected in the design is too small, or it is replaced with the liquid nitrogen regulating valve incorrectly during installation, or the regulating valve, liquid-air adsorber and supercooler are blocked during operation, it can reduce the passing capacity of liquid air. Even if the regulating valve of the liquid level is opened to the maximum, the liquid level of the liquid level will continue to rise. In order to maintain the stability of the liquid level of the lower tower, we have to adopt the method of enlarging the liquid nitrogen regulating valve to reduce the reflux liquid of the lower tower, which will destroy the normal rectification working condition of the lower tower. Because the amount of liquid nitrogen is too large, the purity of liquid nitrogen decreases, and the purity of nitrogen in the upper tower also decreases, the extraction rate of oxygen decreases, and the output of oxygen decreases. At the same time,...

Besides reducing air loss as much as possible, reducing equipment resistance to increase air volume and reducing loss of running cooling, incomplete loss of heat exchange and leakage as much as possible to reduce expansion air volume, here we analyze the methods of adjusting output mainly from the angle of adjusting rectification working condition: 1) the liquid level should be stable. The stability of liquid oxygen level marks the cooling balance of the equipment. If the liquid oxygen level is high and low, it is very difficult to adjust the purity. Reasonably adjust the expansion amount and the opening degree of liquid-air and liquid-oxygen regulating valve to make the liquid-oxygen surface stable. 2) adjust the purity of liquid air and liquid nitrogen. Rectification in the lower tower is the foundation of the upper tower. The change of the amount of liquid nitrogen and liquid nitrogen will affect the purity of liquid nitrogen and the reflux ratio of the distillation section of th...

What are the causes and phenomena of water ingress accidents in the molecular sieve purification system of air separation equipment? How to prevent it?

Currently, there are three types of high-pressure aerators applied in the air separation plant: 1) Water Bath type. Put the coil into water with steam flowing in. Use hot water to gasification liquid oxygen (or liquid nitrogen, liquid argon. Coil pipe adopts one or more tubes with larger diameter (for example, φ25mm×2 ~ 3mm) winding. Generally, it is made into one layer, and the upper and lower layers are equipped with confluence pipes or collectors (no single one ). Both the import and export pipes face up. The tube material should use aluminum tube or stainless steel tube. Keep the water temperature at 80 ~ 90℃. Its advantages are good heat transfer performance, small volume, light weight and safe operation. The disadvantage is that it needs to consume a certain amount of steam whose pressure is about 0.4MPa. 2) empty bath type. The heat exchanger is placed in the atmosphere, and the low temperature liquid is heated by air to make it gasification. The heat transfer pipe adopts sta...

Why should leak testing of air separation equipment be strictly controlled?

Air separation equipment molecular sieve purifier water inlet accident what phenomenon how to prevent?

What are the reasons and how to deal with excessive hydrocarbons in the main cooling system of air separation equipment?

What is the function and principle of self-cleaning air filter for air separation equipment?

How many adsorbers are there in the purification system of air separation equipment?