| PSA in Refinery |  |
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Recent environmental laws are continually becoming more stringent. Complying with this strict guidelines has been, one of the great challenges for the refinery sector as a whole. The law has been imposed with respect to changes in gasoline and diesel specifications. It is evident that this trend is all set to continue.
There
has been major changes within the refineries to cope up with these
demands. Refineries are investing in hydrocracking and hydrotreating
processes. This have led to the increase in the need for volume and
purity of hydrogen. The Presure Swing Adsorption technology is playing a
crucial role here. These days PSA units are designed in a manner that
achieves up to 99.9999% of hydrogen purity. The recovery rate of
hydrogen varies between 50 to 95%. It is quite common to see Hydrogen
purification plants that can deliver @ 100 Nm³/h to even 100,000 Nm³/h.
PSA units are flexible and reliable. PSA plants can be installed as
stand alone units or integrated with the refining plant itself. Unique
features of PSA plants that are used in refineries include high turndown
ratio and maintaining of recovery and product purity. In Refineries
using PSA plants instead of cryogenic distillation has been able to cut
costs by 60-90%. Using PSA Hydrogen can be purified from a variety of sources. Some of the major sources are the following:
- Hydrotreater purge gas
- Refinery fuel gas stream
- Ammonia plant off-gas ( fully integrated with a refinery)
- Catalytic reformer off-gas
- Coke oven gas
- Styrene off-gas (fully integrated with a refinery unit)
- Syngas from steam methane reformers
- Syngas purification from a unit that employs partial oxidation
- Ethylene off-gas (integrated with a refinery)