What’s that flame at the top of a refinery pipe stack? Flaring 101

Jun 22, 2017   | Categories: Energy, Environment, Fossil Fuels, Issues, Lower Carbon Future
That flame you see burning at the top of a refinery’s pipe stack is an important, safe and regulated part of the refining process.
Although the visual of a flickering flame is eye-catching, there is no need for alarm.
Flaring is a crucial, environmentally sound part of converting oil into gasoline and other products, explains Gilles Morel, Director of Fuels for the Canadian Fuels Association.
“Flare stacks are primarily used to combust flammable gases that are released through pressure relief valves, rather than emit these gases directly to the atmosphere,” he says.

“Pressure relief valves are essential safety devices that automatically release gas to protect against the danger of over-pressuring industrial equipment and possible equipment rupture,” Morel says. “Pressure relief valves are required by law [through] industrial design codes and standards.”

Flaring also reduces emissions that would otherwise go into the atmosphere by 98 per cent, he adds. The process combusts and breaks down gaseous compounds from their original state to carbon dioxide.

How flaring works

During the day-to-day operations of a working refinery, by-products created in the process are collected and routed to recovery tanks for further processing where they are converted into gasoline, diesel, jet fuel and other products. If abnormal conditions occur (such as a power failure, an equipment malfunction or a vessel overpressure), some gases are rerouted to the flare system to be safely combusted, instead of being emitted directly into the air.  

Refinery personnel are constantly monitoring the flare system from an on-site control room.

Rarely, you might see black smoke coming from the flare. That happens when there’s not enough steam available to burn all the hydrocarbons; after a short delay the site personnel adjust the steam as necessary to optimize the combustion process.

People may also notice a rumbling sound coming from the flare. The sound is created by the mixing of vapours, air and steam during the process.

Regulating emissions

Flare stack emissions and smoke are strictly regulated by provincial governments. In recent years, refineries themselves have worked hard to develop systems that recover and reprocess excess materials, which has reduced flaring.

“Flare stacks are generally located at the highest point in a refinery,” says Morel. “This assists with emission dispersion, and complying with ground level concentration limits stipulated by government requirements.”
Read more about how refinery air emissions have dropped considerably since 2003, and how transportation fuels are getting cleaner all the time.
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