How do LNG storage tanks work?
In LNG storage the pressure and temperature within the tank will continue to rise. LNG is a cryogen, and is kept in its liquid state at very low temperatures. The temperature within the tank will remain constant if the pressure is kept constant by allowing the boil off gas to escape from the tank.
What is LNG tank stratification?
When a new cargo of imported LNG is received at a terminal, it may have a different density from the residual LNG (heel) inside the storage tank. This results in the formation of two different density layers inside the tank, which may lead to stratification depending on the density difference.
What is the pressure in an LNG tank?
The LNG fuel tank is a cryogenic container. This means that it stores the natural gas fuel as a highly refrigerated liquid at low pressure. Typically the fuel temperature is about -200°F/-130°C , and the fuel pressure is about 100 psig/6.9 bar.
How are LNG tanks insulated?
The sidewalls of LNG containment tanks are usually insulated with a combination of loose-fill perlite and fiber glass blankets. The tank roof typically has a floating component insulated with closed cell foam. The tank base is usually insulated with multiple layers of high-density cellular glass.
What is the temp of LNG?
approximately -260°F
When natural gas is cooled to a temperature of approximately -260°F [-160°C] at atmospheric pressure it condenses to a liquid called liquefied natural gas (LNG).
What is rollover in LNG tank?
“Rollover” refers to the rapid release of LNG vapour that can occur as a result of the spontaneous mixing of layers of different densities of LNG in a storage or cargo tank. A pre-condition for rollover is that stratification has occurred, ie the existence in the tank of two separate layers of LNG of different density.
What is LNG ISO tank?
LNG ISO Tanks Container Used to transport liquids, gases, and powders as bulk cargo.
What is cargo rollover?
A container rollover, or cargo rollover, is when your container fails to get loaded onto its scheduled vessel and is accommodated on a subsequent ship. There are numerous reasons why containers get rolled, including but not limited to: Overbooking of cargo by the carrier. Vessel skipping the port of loading.
What is boil off in LNG?
During the process of LNG unloading and storage some part of LNG evaporates into gas phase, which is usually called boil-off gas (BOG). BOG can be utilized as fuel, reliquefied, compressed and put into gas transportation network or burned in a flare.
What is normal temperature for LNG?
The methane in LNG has a flame temperature of 1,330°C (2,426°F). In comparison, gasoline has a flame temperature of 1,027°C (1,880°F), which means LNG burns hotter.
How much LNG is in an ISO container?
LNG ISO Tank Container Specifications A 20ft cryogenic LNG ISO container offers a storage capacity of 22,000 liters starting at a 17 BARG working pressure.
What is LNG tank rollover?
Liquefied natural gas (LNG) rollover refers to the sudden mixing of stratified LNG layers, which can cause the generation of significant amounts of boil-off gas which create safety issues significantly in LNG storage tanks. Therefore, understanding of the phenomenon is very important for prevention purpose.
What are the construction methods for LNG storage tanks?
CONCLUSION LNG storage tanks are ideally suited to construction methods employing slip formed or climbing insitu concrete construction combined with post-tensioning. The specific design and installation techniques are very specialised and require the use of specially certified and tested materials and highly experienced contractors.
Who is responsible for the design of an LNG tank?
LNG tanks are typically constructed in a design-build fashion and the principal contractor is responsible for determining the specific design requirements for the prestressed concrete. The post-tensioning specialist will examine the required force profile and detail the spacing and tendon size of the post-tensioning. DESIGN REGULATIONS
How is LNG stored at atmospheric pressure?
LNG is stored at atmospheric pressure in double- walled tanks: the space between the tanks being filled with insulation. The outer walls of the tank are most commonly constructed from post- tensioned concrete.
What is an LNG tank made of?
An inner tank is made of a special steel/nickel alloy to accommodate cold LNG. Thiess and LNG Tank specialist TKK were responsible for the design and construction of the 188,000m3LNG storage tank – one of the largest above-ground tanks in the world at the time.