LNG – a presentation by Ametheus
LNG Basics
Liquefied natural gas (LNG) is natural gas that has been cooled to a liquid state, at about -260° Fahrenheit (-162°C), for shipping and storage. Cooling process reduces the volume of gas by 600 times i.e. LNG becomes 1/600 volume of natural gas, thereby making it convenient to transport by cryogenic vessels. This process makes it possible to transport natural gas to places pipelines do not reach.
Liquefying natural gas is a way to move natural gas long distances when pipeline transport is not feasible. Markets that are too far away from producing regions to be connected directly to pipelines have access to natural gas because of LNG. In its compact liquid form, natural gas can be shipped in special tankers to terminals around the world. At these terminals, the LNG is returned to its gaseous state and transported by pipeline to distribution companies, industrial consumers, and power plants. It is then piped to homes, businesses and industries where it is burnt for heat or to generate electricity. LNG is now emerging as a cost-competitive and cleaner transport fuel, especially for shipping and heavy-duty road transport.
Liquefied Natural Gas consists mainly of Methane (typically methane (85-99%)) and small amounts of other fractions of C2+ components like ethane, propane and butane. It is colorless, odorless, non-toxic, transparent and in liquid form ~45% density of water. Considered as one of the most environment friendly fossil fuel.
As LNG is highly volatile, specialist operators are involved in its transportation.
LNG Trade
For large-volume ocean transport, LNG is loaded onto double-hulled ships, which are used for both safety and insulating purposes. Once the ship arrives at the receiving port, LNG is off-loaded into well-insulated storage tanks, and later regasified for entrance into a pipeline distribution network.
LNG can also be shipped in smaller quantities, usually over shorter ocean distances. There is a growing trade in small-scale LNG shipments, which are most commonly made using the same containers used on trucks and in international trade, specially outfitted with cryogenic tanks. Other small-scale LNG activities include “peak-shaver” liquefaction and storage facilities, which can hold gas compactly for when it is needed in local markets in the U.S. during times of peak demand. LNG is also sometimes imported or exported by truck from this kind of facility.
A Typical LNG Chain
Primary LNG Project / Chain Components are:
- Upstream development of long-term natural gas supply for feed gas to an LNG plant
- Downstream development of liquefaction , storage and loading facilities
- Marine transportation
- Downstream development of receiving terminals for regasification and pipeline transportation to market
Applications of LNG
Natural Gas is not only efficient, clean, eco-friendly and flexible in control, it meets many of the fuel requirements of modern industrial society. LNG’s main applications are:
Electricity generation : Fuel for base load and combined cycle/ co-generation power plants.
Public and commercial : This clean fuel, which is cheaper than LPG, can be used as piped gas for households. In the West, most household consumption is accounted for by piped gas, whose use is increasing rapidly.
Industrial : Industrial : Under boiler fuel for steam raising and heating applications.
Alternative motor fuel to diesel : The use of natural gas as fuel for automobiles is increasing rapidly as it is 30 to 40% more efficient and much cleaner than traditional fossil fuels. With only one carbon and four hydrogen atoms per molecule, it is the most eco-friendly option and is gaining increasing relevance in the age of Global Warming and Climate Change.
Petrochemicals : Several vital chemical products, e.g. methanol, can be derived from natural gas.
LNG Terminals
Natural gas arrives at LNG terminals as super-cooled LNG, which is then warmed up in regasification units located at the terminal to regenerate natural gas in its gaseous form. This regassified LNG (RLNG) is then supplied through pipelines spanning across the country. Alternatively, LNG can also be delivered using LNG trucks.
India has LNG terminals at Dahej, Hazira and Mundra in Gujarat, Dhabol in Maharashtra, Kochi in Kerala and Ennore in Tamil Nadu.
LNG Storage and Transportation
Natural gas in the form of LNG offers remarkable flexibility in storage and transportation. On land, natural gas is conveniently delivered to consumption centers in its gaseous form through pipelines. But if pipeline transportation is not an option available, natural gas is converted and stored as Liquefied Natural Gas (LNG) at minus 162 degrees Celsius, by cooling it down using a refrigeration cycle. At this super-cool temperature, natural gas turns into its liquid form. The resulting LNG occupies only 1/600th of its original gaseous volume and is thus transported efficiently in large specialized tanker ships that have the requisite onboard cryogenic storage facilities (thermally insulated tanks) to keep LNG in liquid form.
Upon arrival at an LNG import terminal, LNG is regassified by heating it to convert it back into its gaseous form, which is called R-LNG (regassified LNG). This natural gas regenerated from LNG is transported swiftly via pipeline networks stretching thousands of kilometers. LNG can also be delivered employing LNG trucks with double-walled insulated cryogenic tanks to store LNG at ultra-low temperatures.
Similarly, on-ground LNG storage tanks are specially designed cryogenic tanks that maintain frigid conditions to keep LNG in the liquid state. These tank systems are specially engineered to use auto-refrigeration to keep the pressure and the temperature in the tank constant.
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