Flare gas recovery is the process of recovering the waste gases that would normally be flared. The recovered gases can be reused within the facility's fuel gas system. It can be used as a refinery feedstock or for re-injection. Flaring in the U.S. is addressed by the Environmental Protection Agency (EPA) in Section 111 of the Clean Air Act of 1970.
Flare gas recovery systems are specialized compression systems, which attempt to recover and recycle gases and emissions, like hydrocarbons and carbon monoxide, which would normally be burnt during the flare process. There is an array of recovery methods, but there are some particularities in regards to the way that these systems work. In general, they are designed for gas recovery from a flaring flame using a series of steps to collect the gaseous emissions, while separating them from the combustible elements of the burning fuel. The process is called "recombining" because the combustion products are often recovered along with the flue gas, leaving behind the gaseous product and the original flame.
So, what are the common components of typical flare gas recovery systems? Well, first of all, there is a storage tank, which is designed to safely store the gaseous emissions until the need to recover them arises. Also, the system will have a fuel cell, which is responsible for initiating a flaring reaction with the gas, and driving it through the system's heat exchanger to generate high-temperature gas (i.e. flame) and high-pressure gas (i.e. steam).
As you can see, the most important part of flare gas recovery systems is its fuel cell. This part is responsible for initiating the actual flaring reaction with the gas, as well as converting the gaseous product into a usable liquid, for use within the refineries.