An Overview of Flare Systems for the Oil and Gas Industry

Introdution

Flare systems provide hydrocarbon facilities with safe and efficient discharge of relief and waste gases by controlled open flame burning. Process streams are routed to closed loop flare systems during unplanned over over-pressurizing of equipment, plant shutdowns, or startups to avoid over-pressurizing equipment and releasing process fluids to atmosphere.

Until the late 1940s, all hydrocarbon processing facilities used to vent relief and waste fluids unburned to the atmosphere during maintenance periods or process upsets¹. These gases may have contained potentially toxic and flammable vapors and as a result, flare systems were developed. This article provides an overview of flare systems used in oil and gas production and processing operations.

Types of Flares

Flare systems can be classified as elevated, horizontal, or slanted. Elevated flares are generally oriented to fire upwards from a discharge point at a higher elevation than surrounding grade or nearby equipment (See Figure 1). On the other hand, horizontal flares or burn pits incorporate burners which discharge into a pit or excavation to retain liquids released with gases. Heat shields are usually used to protect personnel from heat radiation. A Coanda flare (shown in Figure 2) is a slanted flare usually used to meet low radiation, noise, and space requirements at production platforms.

Flares may also be classified as single point or multipoint (Multiburner). A single point flare is basically an open pipe with a single exit point, whereas multipoint flares have more than one exit point. An example of a multipoint flare is shown in Figure 3. Multipoint flares are considered to be friendlier to the environment due to staging feature which:

• Improves combustion by providing flared gas with better mixing with air
• Eliminate smoking by providing differential operation of each burning stage