[Chemistry Class Notes] Liquefied Natural Gas Pdf for Exam

Liquefied Natural Gas (LNG) is generally methane or natural gas that has been liquified to make storage and LNG transportation easy. It is almost six hundred times smaller than natural gas in itself when the latter is in the gaseous form, making it easy to be shipped overseas. LNG is produced when natural gas is cooled below its boiling point, that is, -162°C or -258°F. And then, it is stored in containers that are double-walled cryogenic or are slightly above what we call atmospheric pressure. It is very easy to convert it back to the gaseous state, and this can be done by just raising its temperature. This is the LNG liquefaction process that takes place in LNG plants.

Usage and Transportation

LNG is far more practical as compared to Liquified Petroleum Gas (LPG), or other liquid gases that there are, especially when it comes to usage in large volume since it has the very same composition that natural gas does! This fact, along with the steadily growing demand for natural gas, has caused a stimulation for LNG production. What’s more, LNG technology makes it very possible to use natural gas from those remote parts of the world where there was previously no commercial use, and it was, in fact, being burned or flared as it is called.

There are special tankers called the LNG carriers that have supercooled cryogenic tanks that transport this liquified gas from countries like Algeria, Indonesia, Australia, and Qatar to the markets that are in Japan, Surprise, and China. At the beginning of the 21st century, there was an expansion of the natural gas pipelines in the United States, and this resulted in the nation being the net exporter of LNG, where it previously was just the vital importer of this gas.

Liquefied Natural Gas is generally reverted back to its gaseous state or is regasified as it is called, at the import terminals that are in the recipient counties. It is then injected into the natural gas pipelines and then, in this way, is transported to power plants and other distribution companies for the various industrial needs that there are. 

How is LNG Made?

As mentioned above, liquified gas is primarily methane and is made when the temperature of natural gas is brought down to -258°F. What happens during this cooling process is that the other components of natural gas like the other hydrocarbons, sulfur compounds, oxygen, nitrogen, carbon dioxide, and water and gradually but steadily removed, leaving behind almost pure methane. This is an essential process as many of the compounds that get removed during the process of liquefaction can potentially damage the downstream facilities that there are. Another risk is that some compounds could freeze instead of liquefying as is needed.

LNG is considerably denser when compared to gaseous natural gas; however, when it comes to volume, it is much lighter than water. It actually weighs less than half of the weight of water, and if it were to be spilled on water, it would actually float. The energy-dense yet lightweight nature of the gas makes it easy to transport. This is done in large tankers that are ocean-going that have double hulls to ensure extra insulation to help keep the LNG cold as it should remain. The process of refining natural gas and LNG liquefaction happens in an LNG plant.

It is also important to talk about floating liquefied natural gas facilities. Floating liquefied natural gas facilities are, as the name suggests, flotation production storages. They also function as offloading units that conduct LNG operations for those natural gas resources that are offshore and developing.

Advantages and LNG Uses

As mentioned, natural gas liquefaction results in Liquefied Natural Gas, which is very easy to transport. This makes it possible for isolated natural gas deposits like pipelines to have the gas recovered and also transported with the use of tankers. These tankers are very safe, and it is estimated that they have sailed over a hundred million miles with no death or major shipboard accident even though some land-based, on-site accidents have taken place.

However, LNG is neither explosive nor flammable like a liquid is. When it starts vaporizing, it may potentially be flammable or explosive but only in the range of 5-15% of natural gas in the air. When it is at less than 5%, there isn’t enough natural gas to burn, and above 15%, there’s not enough oxygen for it to burn.

LNG also allows convenient storage even in off-peak times. This can be referred to as ‘peak-shaving,’ and it is about the storage of the natural gas that is a surplus, in LNG form in those periods where energy consumption is lower. When the demands for energy rise, it can be regasified and then be used to meet the higher levels of demand, thereby preventing energy shortage.

LNG uses are vast and many, and to sum it all up, we can say that it is a source of energy. When LNG gets regasified to its original state, it can be used across industrial, commercial, and residential sectors for things like generating electricity, cooking, heating, and also for the manufacture of a rather large variety of products. It is also used as fuel for vehicles that are heavy-duty and also otherwise.