Brochure
Joule-Thomson/Expander Bypass Control Valve
The Joule-Thomson effect is leveraged throughout all of
the primary liquefaction processes to achieve cooling
of the feed gas or the refrigerant streams. It is used to
achieve cooling of liquids, gases, or multi-phase uids.
Traditionally, this effect has been facilitated by a control
valve that reduces the pressure of the uid signicantly
and induces the desired cooling. Because of the elevated
pressure drop, the valve can experience excessive noise
levels if not addressed properly. It also experiences very
low process temperatures and must be capable of precise
throttling down to full cryogenic temperatures.
In some facilities, expanders are utilized to facilitate
Joule-Thomson cooling while also recovering energy from
the uid to improve overall process efciency. Expanders
are used in both gas and liquid applications (commonly
referred to as hydraulic turbines in liquid applications).
Regardless of the uid, expander bypass valves are
installed in parallel with expanders to ensure process
availability. In instances when the expander is required to
go ofine, the bypass valve is opened to facilitate Joule-
Thomson cooling of the process stream and allow the unit
to continue operating in the absence of the expander. The
bypass valve must be highly responsive and reliable to
ensure process availability. It is also commonly subjected
to a large pressure differential, which creates the potential
for signicant noise levels in gas applications and ashing
in liquid applications.
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