KVOC system proves its worth

	“Ragnhild Knutsen” of Knutsen OAS Shipping, a 129,154 DWT crude oil/shuttle tanker built 1987 seen here loading crude offshore in the UK sector of the North Sea.

Emission of VOCs (Volatile Organic Compounds) is a serious environmental problem, and reducing these emissions is a matter of urgency, not least in the North Sea. Statoil admitted last year that they would not meet the Norwegian government’s mandatory target for 2003. Nor will they meet the 2004, 2005 or 2006 targets if the company persists with a VOC technology, which increases emissions and not reducing them, by just recovering released non-methane VOCs, rather than prevent their release in the first place.
There are 30 or so offshore loading vessels in the North Sea, and those working in the Norwegian sector are more or less forced to use the energy-intensive and potentially dangerous Statoil system in order to operate. Last year we introduced an alternative, much more efficient system, which for some obscure reason is not allowed into the Norwegian sector.

However, we understand that other countries, like the United Kingdom and Denmark welcome the so-called KVOC system, developed and introduced by Knutsen OAS Shipping on the shuttle tanker Ragnhild Knutsen. A process to have the KVOC system approved in the Norwegian sector has begun.

Paired with VOCON
Last year several improvements to the original system were made culminating in the installation of an ultrasonic flow-measuring device to monitor the emissions, particularly during loading, but also in transit.

Knutsen also installed the VOCON valve produced by Pre-Vac in Denmark to ensure control of the pressure and improve performance even further. Since then Ragnhild Knutsen has made several shuttle trips and the results are promising. It turns out that KVOC and VOCON is a good match. VOC reduction during loading is 80 per cent or more, and emission during transit, which is acknowledged as a problem, is eliminated.

Normally there is a build-up of pressure during transit and VOC would be released, but now inert gas had to be added to prevent too low inert pressure.

Crude behaviour the key
When loading through the KVOC, the oil is not exposed to conditions that would influence the behaviour the crude oil. For the same reason the weather will have little influence on emissions.

Having solved the technical issues it remains to get the system approved by the Norwegian authorities. But by approving the KVOC system, the authorities will have to look more closely at the Statoil VOC system. It is a question of reducing VOC emissions as well as a number of safety issues. The KVOC system is also considerably cheaper to install and carry no additional operating costs, since it is part of the vessel’s loading system. Neither does it require additional power. The KVOC system is also installed on a shuttle tanker newbuilding to be chartered by DONG for offshore loading in the Danish sector.

Other countries around the North Sea have not got Norway’s mandatory emission targets, but Norway has so far not allowed technology, which could meet those targets.

//Petter Arentz