| 摘要 |
Hydrocarbon liquids are transported from a subsea wellhead to an above-surface hydrocarbon processing facility along a pipe-in-pipe flowline wherein the hydrocarbon-transporting pipe is placed coaxially within an outer carrier pipe and the annulus between the pipes is filled with thermally insulating material. The hydrocarbon liquids have their temperature maintained above solidification/precipitation temperature by heat from an active heating system in accordance with the invention. Hot liquid, preferably hot water, is passed along the annulus, either along a single pipe or multiple pipes installed in the insulation-filled annulus, or along an inner annulus formed by a water pipe added concentrically around the hydrocarbon-transporting inner pipe, inside the outer insulation-filled annulus. The water or other suitable liquid can be heated in a heater at or adjacent the subsea wellhead, or the liquid (when water) can be heated by a water heater in the above-surface hydrocarbon processing facility, in which case the heater can be a pre-existing water heater adapted for use in the invention.
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