The World Bank recently revealed 141 billion cubic metres (bcm) of natural gas was flared in 2017. The figures reflect the global change in attitude towards routine flaring and its reduction, with Russia actioning the biggest decline last year and Nigeria now actively pursuing new regulations to restrict flaring.
Operators are also making moves to improve infrastructure, ensuring processes and equipment are in place to manage flaring and maintain the performance of flares. One way to improve flare efficiency is using knockout drums to ensure the right mix of air and fuel is provided for flaring.
When natural gas – also known as associated gas – is found in oil fields, operators face difficulties in transporting it from processing plants and a lot of gas is flared. While this is largely done for safety reasons to relieve pressure and reduce the risk of on-site explosion, burning natural gas is also far more environmentally friendly than venting it directly into the atmosphere.
The most efficient flaring occurs during complete combustion, when the right mixture of fuel and air is ignited at the top of a flare stack. This particular process generates Carbon Dioxide (CO2) and water, and the resultant flare does not produce visible smoke.
The liquid factor
When gas is flared, it is crucial it does not contain liquid. If a mix of gas and liquid was to reach the top of the flare stack, the burning gas would fall downwards and have potentially dangerous consequences.
To avoid this, operators purify gas from liquids with a knockout drum – horizontal or vertical vessels designed to remove and accumulate condensed liquids. Residue that cannot be recovered from oil and gas production is collected in the knockout drum and – under high pressures – becomes liquefied. The recovered liquid (or condensate) collects at the bottom of the vessel and is then disposed of, while non-liquefied gases travel up the flare stack to be burned in the flare system.
Horizontal knockout drums are preferred for high quantities of liquids and gas, while vertical vessels are often used for low amounts or if there is little space available.
A detailed account
To help ensure knockout drums are having the desired effect at flaring sites, oil and gas companies will need to invest in accurate monitoring and measurement applications.
One of the most accurate ways to measure flare gas is with ultrasonic technology. Fluenta’s FGM 160 Flare Gas Meter uses ultrasonic technology to effectively provide measurement data, allowing oil and gas companies to ensure flaring is performed efficiently.
For more information on Fluenta’s FGM 160 Flare Gas Meter, click here.