PSA oxygen gas plants are plants producing oxygen using the PSA process.
Oxygen is used for various industrial applications and hence needs to be
produced in large volumes. There are usually two methods to do this:
cryogenic process and the PSA process. The PSA technology has today emerged
as a very popular technique for the production of commercial production of
oxygen gas and suited for both small and medium sized units. The PSA process
is very useful for small applications like oxygen production for asthma
patients.
What is PSA?
PSA stands for pressure swing adsorption. It is dependent on air being
filtered through aluminosilicate minerals, called as zeolites. In the PSA
process, nitrogen gas is adsorbed into the zeolites and oxygen (and argon)
pass through. It is a technology in which some gas species are separated
from a mixture of gases under pressure. The PSA technique is very
environment friendly and can also remove other gases such as carbon dioxide
from industrial waste gas streams.
The
process
- Compression of feed air and conditioning: Using an air
compressor, the ambient air gets compresses, dried by an air dryer and
then filtered before entering the process vessels.
- Adsorption: The next step in the PSA process of producing
oxygen is the adsorption process. The process removes impurities and
produces almost 100% pure oxygen. The pre-treated air passes through a
vessel filled with Zeolite Molecular Sieve (ZMS). Here nitrogen and
other gases gets adsorbed and most of the oxygen pass and this continues
till ZMS is fully exhausted.
- Desorption: The saturated ZMS is regenerated. This is done by
pressure reduction, using a simple pressure release system. This is
after the adsorption process. The waste stream moves into atmosphere.
While regenerated adsorbent is purged with oxygen. This is again used
for the generation of oxygen.
- Receiver: The adsorption and desorption process take place at
equal time intervals, and there is continuous generation of oxygen. By
using a connected oxygen receiver, a constant product flow and purity is
maintained, which can store the oxygen with purities up to 95%. Finally,
the plant produces a constant flow of on-site produced oxygen.
Features of PSA Oxygen Plants
Usually the design of PSA oxygen plants rely on many factors like:
- Zeolite bed packing
- Bed length
- Diameter
- Rate of infeed air
In medical oxygen PSA plants, power efficiency is not given much
preference compared to robustness, process stability and oxygen purity. In
large sized PSA plants, the PSA process is only cost effective while
operating at maximum separation efficiency.
VPSA Oxygen Plant Unit
Using VPSA (vacuum pressure swing adsorption), oxygen is produced in small
demands for various applications. A typical VPSA unit is shown below:
Benefits of Psa Plants
Compared to other processes used in gas plants, the PSA process has certain
benefits:
- High operational efficiency
- Lowers power costs
- Full safety
- No hazards involved as with bulky gas cylinders
- Low pressure drops
- High output pressures
- Independent on-site production
Applications of PSA Oxygen Plants
- Steel industry
- Pulp and paper industry
- Glass and enamel industry
- Drinking water supply
- Chemical industry
- Biotechnology industry
- Waste water treatment and waste disposal industries
PSA
Oxygen Gas Plant
