Elengy: Receiving shipments

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Receiving shipments

The standard procedure for receiving and unloading an LNG tanker is as follows:

The tanker reaches the harbour;
The harbour master’s office—which is the harbour’s equivalent of a traffic-control tower—may ask the tanker to moor in the harbour;
The harbour pilot boards the tanker and brings it to the dock with the help of tugboats. The ship is brought alongside and tied off before cables are attached for equipotential bonding, communications and safety;
Ship-shore inspection takes place once the vessel has been made fast;
Readings are carried out to check the level and temperature of the LNG in the tanks to determine the amount carried;
Gas and LNG “arms” are connected and subsequently purged with nitrogen;
Ship-shore safety tests are carried out;

Unloading begins:
- The unloading arms are cooled as the LNG slowly begins to flow
- The flow of LNG is steadily increased to its nominal rate
- Unloading continues at the nominal flow rate, with all tank pumps operating at the same time
- The flow of LNG is gradually slowed as unloading ends
- The LNG and gas transferred are analysed
- The tanker is ballasted concurrent with the unloading operation;

The net energy and volume transferred are calculated and contract documents drawn up;
The LNG unloading arms are purged, warmed and disconnected;
The ship is resourced (food, fuel, nitrogen, etc.);
Unloading arms and ship-to-shore cables are disconnected;
The harbour pilot boards the ship;
The ship casts off and is assisted by tugboats;
All clear for engine and the harbour pilot returns to shore.

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Unloading operations on board the tanker

LNG transfer

The ship’s submerged tank pumps are used to transfer the LNG to the unloading arms and on-shore pipes. The terminal sends boil-off gas back through the connecting arms to control pressure in the tanks.The cargo pumps are shut down when levels have reached the amount set for the LNG to be left at the bottom of the tanks. In some LNG supply chains, the LNG tanks are completely emptied.

Ballasting the tanker

Ballasts are filled with water at the same time as the LNG is pumped out.

An LNG tanker’s complete schedule comprises:

Loading
Transporting the LNG (out)
Unloading
Returning on ballast (back).

Vessels are taken out of service for major maintenance operations, which may last several weeks.

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Credits

© Mediacenter GDF SUEZ / Interlinks Image / Eric Larrayadieu, Laurent Monlau.

© Mediacenter GDF SUEZ / Gilles Crampes, Franck Dunouau, Philippe Dureuil, Pierre-François Grosjean,
Cédric Helsly

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FAQ

What is natural gas?

Natural gas is principally composed of methane (CH₄) and is found in natural reserves. As a primary energy source, it offers many qualities, and is the cleanest fossil fuel.

It is appreciated for its high calorific value, ease of use, and environmentally-friendly composition.

Why does natural gas smell bad?

Natural gas is odourless, but an artificial odorant is added to enable detection in the event of a leak.

Why do people say natural gas is clean?

When natural gas burns it does not emit dust, soot or smoke, producing only water vapour and carbon dioxide, much like human breath, which is then transformed back into oxygen by plants. It is the most energy-efficient of all fossil fuels on the market.

Is there a risk of explosion at an LNG terminal?

An explosion of natural gas can only occur if the following three factors occur simultaneously:

a gas leak in an enclosed space
a mix of air and gas of between 5% and 15%
a spark or flame.

Every care is taken in at LNG terminals to prevent these three things occurring at the same time.

Can I visit an LNG terminal?

For reasons of national security, our sites may not be visited by the public.

I am a student and would like to find out about LNG terminals. Where should I go?

Please use the Contact page to submit any requests and we will get back to you as soon as possible.

I am looking for a job and would very much like to join your company. Where should I send my application?

You can visit our Recruitment section where you will find details of our jobs along with openings. Any applications for jobs not listed under openings will also be considered.

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Glossary

The following terms are defined for both singular and plural forms. The time reference is French legal time.

Aggregated allocated quantities

Corresponds to aggregated Shipper send-out allocations in kWh 25°C at the interface between the LSO and the TSO.

This information is provided at 7h00 LT for the preceding gas day.

Aggregated Inventories

Amount of gas in kWh 25°C belonged by the shippers in the tanks of the LNG terminal at the beginning of the day.

Aggregated nominated quantities

Corresponds to aggregated Shipper send-out nominations in kWh 25°C at the interface between the LSO and the TSO.

This information is provided at 18h00 LT for the gas day ahead.

Available capacity

Corresponds to the available commercial capacity of the LNG terminal, i.e non subscribed capacity, expressed as the daily average of the month, in kWh/J at 25°C.

This information is updated daily.

Available Firm Capacity

Difference between Total Firm Capacity and the amount of booked capacity.

Cogeneration

A technology that enables a single fuel source to produce both thermal energy (heat and/or cold) and electricity at the same time.

Combined-cycle power plant

A power station that comprises a gas turbine generator whose exhaust powers a boiler. The steam from the boiler then drives a turbo-generator.

Delivery Conditions

Operator’s obligations concerning the physical characteristics of the natural gas being delivered (pressure, temperature, etc).

LNG

Liquefied Natural Gas

LNG Terminal

Facilities providing reception, storage, and regasification of liquefied natural gas (LNG) and transferring the natural gas (in its gaseous state) to the Main Network

LNG Terminal Access Contract

Contract between the Operator and a Shipper, stating the reception, storage and regas conditions for LNG cargoes delivered by the Shipper to an LNG terminal.

Main Network

High-pressure, large-diameter facilities linking connecting points with neighbouring networks, underground storage facilities and LNG terminals, to which are connected the regional transport networks and a number of industrial consumers and retail networks.