Bundles and towed installation

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Bundles and towed installation

ACTIVE HEATING SYSTEMS

ƒ Electric heating ƒ Induction

ƒ Wire induces eddy currents – pipe wall heats up ƒ Direct impedance ƒ Current passed down pipe wall ƒ Trace heating ƒ Electric wire heats up – transfers heat to pipe ƒ Hot water ƒ Circulation through internal lines with outer insulation ƒ Flow through pipe and return through annulus ƒ High costs for electrics ƒ Shutdown/startup Bundles can incorporate active heating systems to prevent formation of hydrates or wax plugs. A number of systems are available: Induction heating – where the electromagnetic field around the electrical cable induces surface eddy currents on the pipe causing the pipe wall to heat-up. The induction heating cable does not have to be in contact with the pipe. This means that a cable can be separately laid alongside the flowline; Direct impedance – where a current passed along the pipeline heats the pipe wall; Trace heating – where the electrical cable itself heats up. Trace heating systems require the heating element to be installed in or under the pipeline insulation coating. Trace heating is widely use in onshore applications and is also being marketed by Technip in their heated pipe-in-pipe system; Hot water circulation incorporating heat-up and return flowlines within the bundle; Circulating hot water through a closed loop within the bundle, utilising a single flowline and the annulus of the insulated carrier pipe. The latter system is used on the Britannia flowline bundles. However, there are considerable operating costs involved in continuous electrical heating of lines. It may be best reserved for shutdown and startup operations.

BRITANNIACIRCULATIONSYSTEM