Vapor Recovery & Liquefied Gas Transfer

 Pictured:  The PROPANE MISER
What is a vapor recovery unit (VRU)?

A vapor recovery unit is primarily composed of a scrubber, reciprocating gas compressor, motor, and switchgear. Its main purpose is to recover vapor normally discarded by releasing to the atmosphere or through a flare. The pressure switch detects pressure variations inside the tank and turns the compressor on and off. The vapors are sucked through a scrubber, where the trapped liquid is returned to a liquid pipeline or storage tank, and the recovered vapor is pumped into gas lines.

Corken's reciprocating gas compressors are used to boost the pressure in pipelines and scavenge vapors from well sites and tank farms (click on the Vapor Recovery illustration to the left or the link below it for more details).

Typical applications include…

Typical jobsites for vapor recovery units include propane bottle filling stations, petroleum tank farms, pipelines, well sites where fugitive emissions are an issue, refineries, chemical processing plants, recycling plants, and gas utilities.

By adding a four-way valve, a vapor recovery unit can be used in a liquefied gas transfer application. A common example is tank car unloading. The principles of the liquefied gas transfer are fairly simple. With the use of a vapor return line, a reciprocating gas compressor reduces the pressure in the storage tank and increases the pressure in the tank car. The increased pressure forces the liquid through a liquid return line at the top of the tank car and through the liquid line at the bottom of the storage tank (click on the Liquid Transfer illustration below or the link below it for details).

Click here to see a short video on how a liquid transfer unit works.
Recommended reciprocating gas compressors…

Corken's PROPANE MISER is the first and only 2-stage compressor skid technology that captures all propane from a railcar down to 0 PSIG.

Corken's single-stage reciprocating gas compressors work well in low pressure recovery. In high pressure applications with working pressures up to 600 psig, a two stage compressor is recommended. For high flow and large volume applications like scavenging from several well sites or a large storage tank, Corken’s horizontal reciprocating gas compressors are a great choice.

If the application site does not have electrical power for a motor, the compressor can be driven by a diesel powered engine.

Materials of construction…

Materials of construction are based on the type of gas being recovered. For example, natural gas typically uses Buna-N O-rings with aluminum gaskets while process gases typically require a more exotic O-ring material like Kalrez® (Kalrez is a registered trademark of DuPont) or PTFE. Corken also offers a corrosion and abrasion resistant coating called MC1002 for all gas wetted components.