What is the use of flare in an industry?

What is flare?

Flare is an industrial safety device mainly used in petrochemical and in refineries. Flares are designed to burn excess hydrocarbons gases that cannot either be recycled or recovered.


The ideal operating condition would be to eliminate the need for flares, which waste hydrocarbons that could be converted into products, increasing profits. However, facilities for recovering large amounts of released hydrocarbons during an emergency are currently not economically justified. The equipment required to recover daily hydrocarbon leakage rates is justifiable and is used in many plants.

During flaring, the flaring system produces carbon dioxide and water vapor while combined with steam and air.

Types of flare system

  • Elevated Flares: The flare tip is between 20 to 150 meters above the ground

  • Ground Flares: Flare tip is about two to three meters above ground and is surrounded by high heat-shield fencing that also serves as a safety zone.

Advantages of Elevated Flares

  • Requires very less ground area

  • Pollutants level can be maintained within allowable limits

  • Distance between the point of discharge from the safety valves and flare stack is less than the ground flare system

Disadvantages of Elevated Flares

  • Maintenance cost and operating costs are high

  • Difficult to maintain.

  • Noise level is comparatively higher than ground flare system

Advantages of Ground Flares

  • No structural support is needed

  • Easy for maintenance

  • Operating cost is low

Disadvantages of Ground Flares

  • Need a large quantity of water

  • Potential water damage to the flare system

  • Possibility to extinguish pilot burners

Why Flare Gas?

There are various reasons for using flare systems in industries. Some common reasons why natural gas is flared are:

  • Pressure relief is used to prevent explosions caused by simply venting large amounts of reactive gases.

  • Removal of waste products due to various chemical processes

  • Combustion of organic compounds safely

Why flaring is necessary?

Flaring is used to remove dangerous gases while causing the least amount of damage to the environment. It is used in chemical plants to safely regulate pressure and in wells to handle natural gas release. Alternatives, such as piping the gas to a plant or capturing and using it on-site, are very appealing.

Functions of flares

The functions of a flare system are:

  • Safely collecting gas wastes from the process in order to keep the equipment within its operating pressure limits in the event of depressurization or valve opening.

  • Separating the gas and the condensates in the scrubbers

  • Sending the gas to the flare to be burned

Components of flaring system

The normal flaring system discharges all relief inside a unit. A flaring system consists of the following components. They are:


  • Collection pipe

  • A flare line to the site

  • A knockout drum is designed to collect hydrocarbons (liquid) from the gas stream

  • An assist system to control burning smokeless

  • A flare stack with flare tip

  • A fuel gas system for pilots along with ignitors

  • Controls and instrumentation

How Flares Work?

Each drum, column, or capacity that operates under hydrocarbon pressure is connected to the flare network via one or more valves, as well as various pressure control valves (PCV) and blowdown valves (BDV)

During normal operation, the amount of gas sent to the flare is minimal, representing only the incondensable fraction of the processed hydrocarbons with a fraction of the Fuel-Gas to ensure a consistent flow rate.

Some flush or purge gas is permanently injected to maintain the flare’s safety flowrate by keeping the burner flames ignited and thus preventing air from returning.

In the event that a component of the installation fails, typically due to an increase in pressure in a vessel, the pressure relief valve opens, allowing more gas to enter the flare.

If the pressure rises too quickly and/or becomes uncontrollable, the safety valves on the equipment open to protect the vessel.

In the event of a more serious incident or an emergency shutdown of the installation, the safety system opens the blow-down valves (BDV).

As a result, the flare system is a priority system on a hydrocarbon processing installation because it protects the equipment from pressure increases that could cause it to explode.

A number of safety and control components are installed to permanently ensure the proper operation of the flare system:

  • There is a flush gas network for the flare manifolds that helps to prevent entry into the air.

  • A pilot light gas network that maintains a flame at the flare tip, for flares that are permanently lit

  • Two or more pilot lights, depending on the diameter of the installation

  • A remote flare ignition system

  • A nitrogen network that can be connected to the flare manifolds for inserting the system before maintenance operations in the case of Cold Vents, in stormy weather conditions, to quench a fire started by lightning

  • There are surveillance cameras to analyze the existence and the condition of the flame

Advantages and Disadvantages of Flare system


  • It prevents to dispose of harmful material
  • No need for fuel for combustion of hydrocarbons
  • Operational cost is low


  • Air becomes more polluted
  • Emission of greenhouse gases increase the atmospheric temperature and affects the ozone layer
  • Produce harmful gases such as SOx, NOx, and CO