Regasification

Cargos delivered by LNG ships are discharged at LNG receiving or import terminals. A terminal basically consists of a berth, unloading facilities, LNG storage tanks, vaporisation equipment, facilities to handle vapour and boil-off gas and a metering station. The tanks at an import terminal are the same as those at an LNG plant, but have larger LNG storage volumes to provide for variations in cargo deliveries and sendout rates.

LNG regasification terminals commonly use one of the two types of LNG vaporisers—integral heated and remote heated vaporisers—to transform LNG back into its gaseous state. Integral heated vaporisers use a source of heat, usually seawater, which is integral to the vaporising exchanger to warm LNG. Remote heated vaporisers use an intermediate heat transfer fluid (e.g. propane) between the LNG and the seawater, which reduces the potential for freeze-up within the heat exchanger.

Regasification terminals normally use seawater as the source of heat. In an open rack vaporiser, seawater flows downward over the surface of vertical heat exchanger tubes, vaporising the LNG flowing up through the interior of the tubes.

To increase process and energy efficiencies, several methods for utilizing LNG cold in industrial processes are being considered, instead of simply discharging cold seawater into the sea.

TEPCO Futtsu Thermal Power Station

Once regasified, LNG is natural gas and can be used in conventional applications. It can be moved into the pipeline system for delivery to a utility or residential consumers or for filling gas cylinders.