Testing section of the small-scale, low-pressure unit showing Plexiglas observation ports allowing scientists to see what is going on, rather than solely relying on instrument records.

After first-stage separation, gas still requires considerable processing to meet product and process equipment specifications.

Removal of liquid droplets using gas scrubbers (separators) represents a particular concern. That is because allowing such droplets to enter compressors and other liquid-sensitive equipment causes serious operational and mechanical problems.

Statoil’s gas separation project was therefore established in 2000 to improve the group’s fundamental knowledge of the gas-liquid separation process.

Such knowledge is needed not only to purchase the best equipment on the market but also when testing and evaluating new designs and improving the performance of those already installed.  

Services of this kind are becoming widely available now that comprehensive test facilities for improving scrubber efficiency have been constructed.

These are located at the Statoil research centre in Trondheim for small- and large-scale pressure units, and at its K-lab facility in Kårstø north of Stavanger in the form of a large-scale high-pressure loop.
 
A new scrubber evaluation method has also been devised by making dew point measurements of the gas after it has passed through a heater or compressor downstream from the separator.
 
In addition, several improvements have been made to the inlet sections of existing scrubbers.

Inlet separation efficiency has been upgraded by 100-150%, for instance, simply by installing a drain on top of the standard inlet vane.

A new type of liquid protection (splash) plate has also improved the internal flow pattern by damping turbulence below the inlet vane, again improving drainage of liquid to the base of the separator.

Drains have recently been installed in scrubbers on the Heidrun field in the Norwegian Sea, on the Troll A platform in the North Sea and at the land-based Kollsnes gas treatment plant near Bergen. The protection plate has also been introduced at Kollsnes and on Troll A.

In addition, Statoil has designed and successfully tested a new type of cyclonic inlet. This generates a spiral flow, where the liquid is pushed outward and downward while the gas moves inward and upward.