"Natural Gas more competitive in relation to coal, the perfect partner for renewable energies"
LNG supply chain consist of 4 inter-reliant segments; gas production/ exploration, liquefaction, transportation and regasification. Each segment has its own specific industrial processes and rules & regulations.
Natural gas is extracted from subsurface reservoirs onshore and offshore and then supplied into main grid via pipelines for further commercial distribution by the gas companies to homes and industries.
The natural gas (predominantly methane, CH4) extracted is filtered and purified while being converted into LNG (Liquefied Natural Gas) from its original gaseous state at (-260⁰F) -162⁰C and that process contains removal of certain components, such as dust, water, helium, heavy hydrocarbons and acid gases, which can cause difficulty downstream. Natural gas is condensed in volume by 600 times into an odorless, colorless, non-toxic and non-corrosive at essentially atmospheric pressure for ease of storage & transport. The density of LNG is around 45% that of water.
Liquefaction plants consist of liquefaction trains (multiple installations arranged in parallel) to compress natural gas into LNG (liquefied natural gas). And a typical liquefaction train consists of a compression area, propane condenser area, methane, and ethane areas.
LNG tankers are double-hulled ships specially designed to prevent hull leaks and ruptures in the event of accident. The LNG is stored in tanks (generally 4 to 5 per tanker) at a temperature of -163°C and at atmospheric pressure.
There are currently 3 types of LNG carrier, each corresponding to a different tank design: membrane tanks, spherical tanks and IHI Prismatic tanks. In 2009, carriers with membrane tanks accounted for more than 60% of world LNG transportation capacity, and more than 85% of orders. This is so far the only technology which allows the construction of large capacity carriers such as the Q-flex (210,000 cu. m.) and Q-max (260,000 cu. m.) vessels.
LNG is transported at a constant temperature and pressure by dedicated carriers, designed and built to meet the most rigorous safety standards.
When LNG reaches its destination, it is returned to a gas at regasification facilities. It is then piped to homes, businesses and industries.
Storage and Regasification
Once received and offloaded, the liquefied natural gas is returned to cryogenic storage tanks – usually varying in capacity from 100,000 to 160,000 cubic meters, depending on the site – where it is kept at a temperature of -163°C prior to regasification. Regasification consists of gradually warming the gas back up to a temperature of over 0°C. It is done under high pressures of 60 to 100 bar, usually in a series of seawater percolation heat exchangers, the most energy efficient technique when water of the right quality is available.
An alternative method is to burn some of the gas to provide heat. On its way out of the terminal, the gas undergoes any treatment processes needed to bring its characteristics in line with regulatory and end-user requirements. Its heating value, for example, may be tweaked by altering nitrogen, butane or propane content or blending it with other gases.