When you drive past a refinery you may see a flame flickering high above the tanks and production units. This might come across as threatening, but there’s absolutely nothing to fear. After all, the so-called stack flares are part of the safety system that guarantees the safe operation of the refinery.
“The stack flares only rarely have a job to do, but when they are actually needed then their function is even more important”, explains Harald Hess, Head of HSSE for the Downstream business and therefore also responsible for safety at the OMV refineries. If operations in a refinery are running normally, then the stack flares will not be used at all. Excess gas from refining processes is reused after treatment as fuel gas in process furnaces or power plants.
We are continuously implementing measures to keep the flaring time to a minimum. Every tonne of hydrocarbons that is burnt via the flares represents a loss for us. We strive to ensure that we feed the entire amount of the excess process gas back into our process furnaces as fuel gas.
Light my fire – only as an exception
There are, however, situations when excess quantities of gas occur that are so large and accumulate in such a short time that reusing them or storing them becomes impossible – for example when plants are taken out of service for maintenance or have to be shut down. “In cases like these, flaring – i.e. burning off the gas via flare stacks – is the best and fastest way of neutralizing the gas in a manner that is both safe and environmentally sound. The gases are then fed into flares via the flare system and undergo complete combustion”, says Harald Hess. On the other hand, the gas from refining processes is far too valuable to be burnt off and that’s why this motto holds true in every refinery: Flare sparingly!
Controlled gas combustion
At the top of the stack flares, at a height of around 60 meters, the combustion process isn’t dangerous – the excess gas is flared leaving behind only water vapor and carbon dioxide. Substances that are also contained in the flue gas of every household from its heating. “Using the flares means that the gases are incinerated completely, leaving no residue behind. This ensures that there is no harm to the environment. With the help of steam, additional oxygen is sucked from the surroundings, allowing the gases to be flared in complete combustion so that the flame doesn’t emit any soot”, explains Harald Hess.
Questions, answers & information
A stack flare in action can be seen from far and wide. In order to combat uncertainty among local residents and to provide a direct line to the company, there is a Green Phone installed at the Schwechat Refinery. This is a 24/7 hotline to the shift manager, who answers any questions or concerns related to the refinery and thereby also on the use of flares.