Steam Beats Hot Water to Keep Heavy Oil Viscous

Tests by Parat Halvorsen on oil spill response equipment (OSR) for offshore supply vessels reveal significant deficiencies with systems using hot water coils.

Norway's Parat Halvorsen undertook a series of trials after a number of lower cost hot water coil alternatives came on the market the market. Kim Kristensen, Marine and Offshore, Parat Halvorsen says: “We have shown empirically that steam injection is the one viable solution proven to keep heavy oil viscous enough for easy loading and offloading.”

Any spilled oil is recovered by OSR-equipped vessels and stored in tanks until it can be delivered to recovery stations on land. The recovered oil has to be heated to maintain a sufficient viscosity for offloading. Parat Halvorsen offers a heating solution based on steam injection from a boiler onboard. It has supplied equipment to a significant number of OSVs delivered by yards including Havyard, STX Norway, Kleven and Ulstein.

Parat has developed the Parat ORO multi nozzle arrangement, which can heat the whole tank from one insertion point. Steam is supplied via the Parat MEL electrical boiler, approved for marine use by class societies including Germanischer Lloyd, Bureau Veritas, Det Norske Veritas and Lloyd’s Register. It has also patented part of the hot water circulation loop used in normal operations interconnecting heat recovery and heat consumers to ensure continuous operation. If an oil spill incident should occur, the vessel operator can bypass the boiler in the hot water loop and re-mobilise the boiler to generate steam for the ORO tank heating system.

To verify whether alternative hot water-based solutions work, Parat installed a compact heating coil and a steam injection nozzle in a test tank at its facilities in Flekkesfjord. Watched by representatives from shipbuilders, owners, consultants and the Norwegian Coastal Administration, the tests measured performance of both solutions in water and in heavy oil. The empirical results showed that heat transfer in heavy oil using the hot water coil was just 10% of that achieved by the same coil in water.