Brochure

Pressure Swing Adsorption (PSA)
PSA is a process that involves separating impurities from
a feedgas mixture to produce a single product gas such as
hydrogen, oxygen, or nitrogen.
Feedgas cycles through fixed-bed adsorbers, which are
surrounded by control valves that use forward and reverse
flow to rapidly switch gases between parallel vessels. Within
the fixed-bed adsorber, impurities are removed from the
product gas at high pressure and then rejected as the
system pressure “swings” to a lower pressure. The ability to
completely adsorb impurities allows the production of high
purity (99.99%) end product.
Applications Discussion
4 | Nonstop High-Cycle Applications
PSA Unit
The PSA unit is a severe service application for control
valve assemblies. High cycling action and tight shutoff
is required. Annual cycle service exceeds 60,000 cycles
for four-bed units like the one shown below.
The challenge of PSA is that control valve assemblies are
expected to cycle as often as every thirty seconds and provide
tight, bi-directional shutoff. Common failures of control valve
assemblies in PSA units include:
•
Stem or shaft breakage due to deficient pinning design
•
Poor valve-actuator-positioner linkages leading to multiple
mechanical failures in a high-cycle environment
•
Loss of shutoff
Your PSA units can achieve longer lifecycles with Fisher control
valve assemblies. Fisher control valve assemblies for PSA
applications are tested to one million cycles to meet Emerson’s
high-cycle quality standard.
The high-performance, linkage-less feedback system in
FIELDVUE
™
digital valve controllers has no wearing parts
so cycle life is maximized. The feedback system eliminates
physical contact between the valve stem and the digital valve
controller. It is completely non-contact and
does not rely on linkages, eliminating the most
common control valve failure mode. Scan the
QR code to learn more about the linkage-less
feedback system in the DVC6200 instrument.