The flare is a vertical stack used to evacuate the excess gas from the refining process so we can burn it safely and in a controlled manner while meeting all environmental requirements.
Our refinery has two flare stacks. The largest has a height of nearly 100 m (328 ft.) and is the tallest structure on the refinery. The smaller one has a height of 64 m (210 ft.). Only one of these stacks is in operation at a time. The taller stack is normally in service, and the smaller stack is used when maintenance is required on the other.
How flare stacks work
Steam is injected into the stack and is mixed with the gas, in order to maintain good combustion, control the temperature and avoid thermal shock. The steam is what can be seen coming out of the flare stack. Our equipment intercepts the gas and returns it to the process unit before it reaches the flare.
There are two situations when we need more flare and thus a larger flame.
The first is when a production unit needs to be safely depressurized. During the Labour Day weekend in 2014, we lost electrical power and had to shut down the entire refinery. Our operations were stopped with no impact on the community or environment, except for the noise made by the flare itself.
Even though the event was unexpected and caused an important loss in production, it offered the opportunity to test the flare system as well as our emergency procedures.
The second situation where we might produce a larger flare is when we need to shut down some of our production units for planned annual maintenance. That often requires us to purge the equipment of any remaining hydrocarbon gases to allow the machinery to be cleaned and inspected.
In both cases when we need to burn excess gas, we make our best effort to limit the impact of the noise on our neighbours, and we follow the most stringent safety and environmental requirements.