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Liquefied Natural Gas (LNG) Carrier

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Cargo System

The vessel incorporates five main cargo tanks each equipped with two main cargo pumps, one stripping pump, spray cooling lines together with appropriate liquid and vapor pipelines. Each tank is connected via liquid, vapor, spray and pressure discharge pipelines with appropriate valves and isolation pieces.

Main Cargo Lines

Each tank is located within a hold space which is equipped with the appropriate pipelines for gas purging and the drip tray with an eductor for stripping in the event of cargo leakage.

Modeling of the tank contents allows multi component liquid phases and two vapor phases to be considered. With respect to the liquid phase this means that the makeup of the LNG can be defined with respect to the amount of Methane, Ethane and Propane as required. In the case of the vapor this means that dilution and displacement methods of gas replacement can be demonstrated with dilution or displacement method occurring being dependent upon the pipeline setup together with the density and speed of inlet of both the gas within the tank and that entering the space.

Level indications together with high level, low level and overfill alarms/shutoff are provided on each cargo tank using both a 'float' and 'capacitance' type of monitoring system. The facility is provided to allow the float system to be raised and lowered as required. The tanks also are fitted with temperature monitoring facilities for both the tank contents and walls together with pressure monitoring enabling the accurate determination of cargo contents and temperature distribution during all stages of operation.

Cargo Tank

All the pumps are of the submerged, electric driven, centrifugal type and are equipped with automatic controls for starting, maintaining operation and stopping.

The manifold comprises of four liquid and one vapor line on each side with appropriate spray cooling connections.