WATCHING THE WORLD GAS FLARE DESIGN FROM NAPKIN TO PLATFORM

Feb. 6, 1995
With David Knott from London If it were not for the paper napkin, many inventors might have had to steal tablecloths-maybe even tables-on which their ideas were first scribbled. One project that took shape on a paper napkin, and which was even known as the Napkin Project in its early days, is a novel flare gas recovery system on Norway's Gullfaks A and C platforms. In November 1990 two employees of Gullfaks operator Den norske stats oljeselskap AS were sitting in an airport cafe, discussing

If it were not for the paper napkin, many inventors might have had to steal tablecloths-maybe even tables-on which their ideas were first scribbled.

One project that took shape on a paper napkin, and which was even known as the Napkin Project in its early days, is a novel flare gas recovery system on Norway's Gullfaks A and C platforms.

In November 1990 two employees of Gullfaks operator Den norske stats oljeselskap AS were sitting in an airport cafe, discussing how flaring associated gas was a waste of valuable hydrocarbons.

The two men were Termed Hope, technical operations manager for Gullfaks, and Magne Bjoerkhaug, process engineer. They wondered if they could turn off the flare for normal operation and reignite it quickly as required, reasoning that this would save about 50% of gas typically flared.

MOST RELIABLE

"We invented a system based on a high integrity pressure protection valve," Bjoerkhaug said. 'This type of valve is used for incomers at onshore plants. It is the most reliable valve on earth and the most technically advanced."

Bjoerkhaug said the idea was to use a fast opening valve, in parallel with a mechanical bursting disc, to hold back gas from the flare tip. In an emergency, the valve would open. If that failed, the disc would burst to allow a rush of gas to the flare tip.

At the same time, an air gun would begin to fire zirconium pellets across the mouth of the flare tip to strike a plate. Pellets hitting the plate would create sparks and thus ignite the gas stream.

"Zirconium is used in ammunition for antitank weapons," Bjoerkhaug explained. "It gives off a large number of sparks with a high amount of energy in each spark."

Hope and Bjoerkhaug's patented idea went into operation last Nov. 16, when the flare for Gullfaks was shut off. The project cost 72 million kroner ($11 million) for two platforms, but Bjoerkhaug says it was worth it.

PAYBACK

"Payback time for Gullfaks will be only 3 years because of Norway's carbon dioxide taxation," Bjoerkhaug said. "The next retrofit installation will cost only 10-15 million kroner ($1.5-2.2 million), and it would cost only 5-10 million kroner ($0.8-1.5 million) to install on a new platform."

Statoil will install a similar system on Gullfaks B platform during the annual maintenance shutdown in August 1996. Bjoerkhaug said operators of another 12 installations worldwide are considering using this invention, while inquiries from oil companies are coming in regularly.

"We conceived the idea because the platform's crew simply did not like the waste of flaring," Bjoerkhaug said. "Gullfaks gas at the time had little commercial value, and the carbon dioxide tax came in only later.

"Now you could justify installing the system on gas prices alone. Alternatively, the amount of oil normally burned as droplets in the flare gas would afford economic justification. We haven't studied deeply the amount of oil flared with gas, but we expect it is quite high."

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