The first person to liquify methane – the primary component in natural gas – was Polish scientist Karol Olszewski, opening the door for Liquefied Natural Gas (LNG) in 1886. More than a century of steady innovation followed, helping to develop the processes that enable today’s 258 million tonnes of LNG to be distributed every year.
A liquid form
Two methods are most commonly used today for liquefying natural gas, occurring at -260°F (-160°C):
- The cascade process – natural gas is cooled by a gas, which in turn has been cooled by another gas, giving the process its name
- The Linde process – the gas is cooled by continually passing it through a cooled tube until it liquefies
Simplified storage and transport
Liquefaction processes have been developed to solve natural gas’ main physics problem: gas is the most expansive of the three types of matter, making it challenging to store or transport in large quantities. The process shrinks the volume of natural gas, meaning the same transport vessel can contain 600 times more LNG than natural gas.
Oil and gas companies are able to use LNG to transport natural gas in large quantities to and from hard to reach wells. LNG is then regasified on land in specialised facilities or on water in Floating Storage and Regasification Units (FSRUs), which saves more than half the cost of an onshore facility.
Keeping it cool
LNG tanks are double-walled to create insulation, yet insulation alone will not keep temperatures low enough. Instead, LNG is stored as a “boiling cryogen” – similar to boiling water, only 470°F (243°C) colder.
The boiling cryogen evaporates within its container, generating a cooling steam that allows LNG to stay at a near constant temperature when kept at a consistent pressure. This process is called autorefrigeration and allows LNG to be transported safely across long distances.
Today LNG is used in areas that are abundant in natural gas but are isolated from major population centres. The small nation of Qatar has planned to raise its total output of LNG from 77 million tonnes to 100 million tonnes per year by 2024. Considering that this is currently nearly 40 per cent of total LNG output, the increase will allow Qatar to become more established in the Oil & Gas Industry.
During this rapid expansion of LNG use across the globe, it is crucial that LNG is accurately measured and managed during its cooling, storage and transportation. Measurement technology – specifically designed to work in such cold environments – is necessary to maintain safety and oversight in the developing Oil & Gas Industry. Ultrasonic technology – used in the Fluenta FGM 160 – is by far the most accurate measurement technique.
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Want to know where the LNG industry is headed? Read our previous blog here.