Bahia de Bizkaia (BBG) is a regasification facility located in Bilbao, Spain. It was established jointly by four partners: BP, Ente Vasco de la Energía – Basque Energy Board (EVE), Iberdrola and Repsol YPF, each holding a 25% stake.
In July 2009, Iberdrola sold its BBG stake to RREEF Infrastructure. In April 2010, Engas acquired BP’s 25% share for €65m. In September 2010, Repsol sold its entire 25% stake to Enagas (15%), RREEF (5%) and EVE (5%).
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The BBG regasification plant was brought online in August 2003. Located in Zierbena, in the province of Biscay, the facility has an LNG storage capacity of up to 300 million centimetres.
The facility supplies natural gas for domestic, industrial and commercial consumption. Its main activity includes regasification of LNG brought in gas tankers. The gas produced at the facility is also used for generating electrical power at Bahia de Bizkaia Electricidad’s (BBE) 800MW plant. Both the BBE and BBG projects cost about €600m.
The regasification facility was built in 30 months at a cost of €264m. It came into operation in August 2003, with the first gas tanker arriving on 8 August 2003. LNG is supplied by the Abu Dhabi Gas Liquefaction Company (Adgas), with BP as one of its stakeholders. Designed to operate 24 hours a day, 365 days a year, the facility can store 300,000 cubic metres of LNG and produce 800,000 cubic metres of gas per hour. The output is marketed by BP and Gas de Euskadi.
Design of the Bahia de Bizkaia plant
The facility sits on a 230,000 square metres site at the existing storage and import installations available for petroleum products. It consists of a boil-off system, an LNG delivery system, vaporisers and pipers. The system is equipped with a Sulzer Espana boil-off collector and compressor, and an Idesa-manufactured re-condenser. There are primary LNG pumps and natural gas burners in the LNG delivery system.
The LNG delivery system also contains two storage tanks, one inside the other, that have a capacity to store 150,000 cubic metres of LNG.
The self-contained storage tanks are designed to keep evaporation losses at less than 0.05% a day. Built completely out of 9% nickel steel, the innermost primary tank consists of an open-top cylinder, a flat metal base and a flat ceiling supported by hangers from the outer concrete tank.
The suspended ceiling provides thermal insulation. To prevent the granular perlite from entering the tank, a metal seal was formed with elongated panels placed above the top ring of the tank. The ceiling is also fitted with an aperture at the centre.
The secondary tank is formed of a metal-concrete foundation slab, a cylindrical-shaped post-tensioned concrete wall and a dome made of metal and concrete. The foundation slab and the ceiling form a single unit without connectors. Cryogenic passive reinforcements are fitted at the ring beam inside the metal tank while the outer side of the concrete tank is fitted with standard passive reinforcements.
The interior of the concrete tank is covered with a protective carbon steel plate lining. An insulation system that encloses the inner tank from all sides covers the inside of the outer tank.
The foundation slab of the tank sits atop a secondary base of 9% nickel steel. Between this base and the foundation slab, an insulating material (foamglass blocks) is positioned to prevent the evaporation of gas. Further insulation is provided by using expanded perlite, glass wool and fibreglass in the walls, the ceiling and the outer surface of the ceiling.
The facility also includes seawater vaporisers, a submerged combustion vaporiser, and safety and relief valves. Regulating and metering stations have been installed at the facility to direct the regasified and odourised LNG to the gas grid or to the combined cycle gas turbine plant on the site next to the regasification terminal. The facility is also equipped with smokestacks to burn production and emergency discharges.
Pipeline
The facility has two pipelines to transport LNG from ships to storage tanks. The first pipeline, measuring 42in in length, runs parallel to another pipeline that stretches 6in.
Gas is transported via these pipelines to a 36in manifold situated in the storage tank zone. To allow gas to flow through, the pipelines are fitted with bypasses.
Process technology
LNG is unloaded from the ship via three unloading arms at a rate of 12,000 cubic metres per hour. The gas is stored in storage tanks that have a design pressure of 290m barg. As the vapour return line in the storage tank is maintained at an ambient temperature to prevent the gas from heating, the gas is allowed to circulate continuously. It flows through the 40in pipeline to the loading zone from where it returns via the 6in pipeline to re-liquefaction unit.
To maintain the vapour that enters the ship below -120°, LNG is injected at the cooling unit of the return line leading to the ships. The wharf area also contains a separator tank that removes any liquid remaining downstream from the cooler.
The surplus boil-off vapours are sent from the storage tanks to the compressor via the manifold. A smokestack system installed at the facility removes the excess gas safely.
Prior to being condensed into sub-cooled LNG, the gas is compressed. LNG pumps installed in the storage tanks push the LNG to the re-condenser via the send-out manifolds. The compressed boil-off gas is then condensed in the re-liquefaction unit, using LNG from the tanks.
From the re-liquefaction unit, the LNG is routed to the send-out-pumps.
The send-out pumps release gas to the vapourisers via send-out manifolds at a pressure of 82barg. The vapourisers that operate at nearly 80barg, convert the LNG into gaseous form by increasing the gas temperature to 0°.
The produced natural gas is released from the vapourisers at a pressure of 72barg and 45barg, with a minimum temperature of 0°. The gas is then routed via the metering station to the natural gas grid at 72barg. Before reaching the gas grid, the gas is odourised with liquid additives such as tetrahydrothiophene. The gas meant for the power plant is preheated with seawater before passing to the regulating and metering station where its pressure is brought down from 72barg to nearly 47barg.
Contractors
The BBG plant was built under a turnkey engineering, procurement and construction contract by the Technigaz, Initec and Sofregaz consortium.
