There is only one method for isolating oxygen from liquid air which is known as cryogenic distillation. There are numerous techniques available for separating oxygen from the atmospheric air such as pressure swing adsorption (PSA) or membrane separation. However, these techniques do not do separation by liquefaction. Cryogenic distillation is the only process that works on achieving separation of atmospheric air through liquefaction. PSA or membrane techniques are used only for generating oxygen on a small scale but it is cryogenic process which is considered the most efficient for producing high purity oxygen.
Benefits Of Isolating Oxygen From Liquid Air
There are many benefits of producing liquid oxygen (LOX) from air. It is an established fact that oxygen is mainly used in its gaseous state except in oxygen propulsion systems where liquid oxygen is used. So why is liquid oxygen preferred over gaseous oxygen? It is because LOX is easy to transport and store. There are many dangers in transporting high pressure oxygen in bulk storage. It could prove to be very hazardous because of high combustibility of oxygen. Any leakage could have really devastating consequences. However strict your safety measures might be still the potential for leakages remains and so does likelihood for hazards, fire and explosions.
Other advantages of producing cryogenic oxygen include its cost-efficiency. With gaseous oxygen businesses tend to lose a great deal of oxygen during transportation and storage. These additional costs ultimately will pile up and hurt the business. This is also the reason why so many small manufacturing businesses are opting for installing LOX plant on their premises. Small businesses face numerous issues getting their oxygen delivery through oxygen cylinders. There are problems flooring occupied by the cylinders and putting in place an efficient safety measures. Personnel are required for handling cylinders. On receiving the cylinders they are required to be put in place allotted for them on the floor of the factory. And waiting for the delivery also constitutes a business activity since it costs money.
Detailed Process Of Isolating Oxygen From Liquid Air
As mentioned above, cryogenic distillation process is used for separating oxygen from liquefied air. The process was developed by Linde & Claude at the start of the 20th century and has continued to be updates with newer developments in the science of cryogenics. The process is contemporaneous with its efficiency, results and performance.
To explain you the entire cryogenic process, it starts with intake of the atmospheric air into the air separation unit where it goes through compression in the air compressor. Next the air is passed through a molecular purification sieve where impurities like carbon dioxide, hydrocarbons and water vapors are removed. So cleaned air now passes through a series of heat exchangers where it is cooled to extremely low temperatures. Then, the air moves into a high pressure distillation column separating oxygen from nitrogen and other gases in the air. Crude liquid form of oxygen is formed at the bottom of the column and nitrogen at the top. Oxygen is collected and moved into a low pressure distillation column where it is distilled to meet industrial or medical specifications.