Gas
processing or air separation is a very old technology of science involving
the separation of air and the identification of oxygen as an atmospheric
component. Such a process owes its origin with the origin of chemistry.
There are basically two basic technologies of air separation: Cryogenic air
separation and Non cryogenic air separation.
While the cryogenic technique is a traditional method, the non-cryogenic
air separation is however a very new technology. Non cryogenic air
separation was developed during the 1970s. While cryogenic gas separation
requires large sized plants for its processing, the non cryogenic process is
considered to be a convenient, efficient, and economical method to buying
gas in high pressure cylinders or for purchasing bulk liquid products to be
vaporized. This process is preferable for many small scale users of oxygen
or nitrogen.
What exactly is Non Cryogenic Separation?
The traditional method of producing nitrogen and oxygen gases is cryogenic
air separation which involves the process of cooling air in large sized
plants to several hundred degrees below zero in order to separate the
component gases. Non-cryogenic air separation is however a very new
technology that requires air to force through through special materials that
selectively pass or retain the oxygen or nitrogen. The physical properties
of the gases other than the temperature like molecular size and mass are
exploited in non cryogenic air separation process to produce discrete and
refine elements of air at close-to-atmospheric temperature. Operating at
near-ambient temperature, these are then used to produce commercially
valuable gaseous products like oxygen and nitrogen.
There are three main technologies involved in non cryogenic process. They
are
- Pressure Swing Adsorption (PSA) used in nitrogen and oxygen
generators
- Vacuum-Pressure Swing Adsorption (VPSA) used in oxygen generators and
- Membrane Separation, used to produce nitrogen gas.
We will discuss in details the three processes in the section:
Advantages of Non Cryogenic Separation Processes
- The non cryogenic technique is much smaller in size than cryogenic
plants
- The basic advantage is that it can be placed directly on the
customer's site
- They are efficient and economical choices when demand is relatively
small and when very high product purity is not required
- They are compact
- They can operate at near-ambient temperature and pressure
- Once installed, they can be brought on-line in less than 30 minutes.
Conclusion
Non cryogenic gas processing is growing up in recent years though it has
not been able to completely displace other existing technologies. The
process is gradually gaining market share in those applications where it has
a clear economic or technical advantage. Both technology-push and
market-pull factors have contributed to the running of non separation
process centered on PSA, VPSA or membrane technology. For many manufacturers
and suppliers, these non-cryogenic gas separations must play against the
long established cryogenic separations involved in bulk gas business.
Non-cryogenic gas processes are on the way to altering the economics of
certain processes and expanding the markets, applications, and uses of
gases. The separation of air into oxygen, nitrogen, natural gas
purification, hydrogen recovery will become increasingly important across a
wide spectrum of very specific applications. Using non-cryogenic separations
all types of gas streams can be processed. According to recent report, the
present and future markets for non-cryogenic gas separations include the
following:
- Air Separation --nitrogen and oxygen enriched air
- Natural Gas Clean up
- Hydrocarbon Clean-up
- Hydrogen Separations
- Hydrogen recovery from off-gases
- Miscellaneous --rare gases, drying
Non-cryogenic
Air Separation
