1. Air Compressor : Air is compressed at a low pressure of 5-7 bar (0.5-0.7mpa). It is done by using the latest compressors (Screw/Centrifugal Type).

2. Pre Cooling System : The second stage of the process involves use of a refrigerant for pre-cooling the processed air to temperature around 12 deg C before it enters the purifier.

3. Purification of Air By Purifier : The air enters a purifier, which is made up of twin molecular Sieve driers that function alternatively. The Molecular Sieve separates the carbon dioxide & moisture from the process air before the air reaches at air separation Unit.

4. Cryogenic Cooling of Air By Expander : The air must be cooled to sub zero temperatures for liquefaction. The cryogenic refrigeration and cooling is provided by a highly efficient turbo expander, which cools the air to temperature below -165 to-170 deg C.

5. Separation of Liquid Air into Oxygen and Nitrogen by Air Separation

6. Column : The air that enters the low pressure plate fin type heat exchanger is moisture free, oil free and carbon dioxide free. It is cooled inside the heat exchanger below sub zero temperatures by air expansion process in the expander.

7. It is expected that we achieve a difference delta as low as 2 degree Celsius at the warm end of exchangers. Air gets liquefied when it reaches at the air separation column and is separated into oxygen and nitrogen by the process of rectification.

Liquid Oxygen is Stored in a Liquid Storage Tank : Liquid oxygen is filled in a liquid storage tank that is connected to the liquefier forming an automatic system. A hose pipe is used for taking out liquid oxygen from the tank.

FAQ :

1.How do variations in the inlet air temperature of a Nuzhuo Cryogenic air separation unit have an effect on the cooling capacity?

The refrigeration capacity of the air separation unit mainly depends on the expander, but the lowest temperature of the air separation unit is at the top of the upper tower, which is about - 193 ℃, lower than the outlet temperature of the expander (- 180 ℃).

2.What is the operating principle of the Nuzhuo Cryogenic air separation unit radial plain bearing, how does the oil film oscillation occur and how can it be prevented?

With the development of large-scale air separation plant, the heat transfer area of the main condensing evaporator is also increasing. If the tube type is used, the number of tubes will be more than 20000, which brings great difficulties to the manufacturing. At present, the plate fin type has been completely replaced.