The regasification process falls into the framework of what is known as the “Gas Chain”. The following image shows the position of the process within that gas chain. Click on point 6 and you will access a graphic specifically on regasification.
A) Reception of Natural Gas
The natural gas is received in liquid form (LNG) from the liquefaction plants on the methane freighters.
These tankers dock on the SAGGAS installations quay and offload using three arms specifically for cryogenic liquids (liquid that has a boiling point below-151.1º) and another vapour return arm.
The process conditions currently allow us to operate with a total LNG offloading capacity of up to 4.000 m3/ h per arm
B) LNG Storage
The liquid natural gas is stored in 4 tanks with a capacity of 150,000 m3 each at a temperature of -160ºC.
The internal pressure of the tanks is controlled by the vapours that are generated by evaporation of the natural gas (boil off).
These vapours are extracted from the tanks and are recovered by several compressors that send the boil off to the reliquefier so as to return it to liquid state and send it to the secondary pumps that push the LNG to the vaporisers.
When, due to particular circumstances in the plant, it is not possible to recover these vapours, they are diverted to the flare, where a controlled combustion of the same takes place.
C) Vaporisation and shipment
The regasification process is undertaken in two vaporisers. The plant has two types of vaporisers: 4 seawater vaporisers (with a capacity of 200,000 Nm3/h) and 1 submerged combustion vaporiser (with a capacity of 150,000 Nm3/h), which will operate during the maintenance periods of the other vaporisers, or, if necessary, to supply peaks in demand.
Through the seawater vaporisers, the LNG is transformed into vapour after being heated to a temperature greater than 0ºC with seawater. In the case of the submerged combustion vaporiser, the LNG is heated and vaporised using a burner submerged in the water that uses natural gas as fuel.
The natural gas produced in the vaporisers is introduced into the Basic Network of Gas pipes, after passing through an odorising and measuring station.
