Saudi Arabian Oil Company

Mazen Mashhour

M Rashid Khan

Rashid M Khan

Apparatus for enhancing combustion of an undesired chemical to minimize the formation of smoke during operation of a flare stack for the discharge of a flare feedstream includes a plurality of high-pressure air nozzles spaced apart below and around the periphery of the stack outlet. Each nozzle is directed toward the stack outlet and in the direction of the feedstream's movement. High-pressure air from the nozzles forms a plurality of high-velocity air jets to produce a moving air mass that draws additional atmospheric air into the air mass moving toward the stack outlet to enhance combustion of the flare feedstream. Analytical means determine the stoichiometric oxygen requirements, and an air-flow valve controls the flow rate of the high-pressure air to the nozzles. Air flow control means adjust the mass flow-rate of high-pressure air based on minimum oxygen requirements determined by the analytical means, whereby the oxygen content of the air flow at the stack outlet meets or exceeds the requirement for the complete combustion of the feedstream.

Flare stack combustion method and apparatus

High-pressure air is discharged in the form of jets moving at a high velocity from nozzles mounted on a ring around the interior of the flare stack, placed at a predetermined distance from the flare tip and the portion of the surrounding stack wall downstream of the jets is perforated with air passages to admit atmospheric air. The high-velocity air movement induces a larger volume of air from the atmosphere to enter the stack where it rises to the flame zone, thereby lifting the flame and enhancing turbulent mixing of air and gas in the flame zone. Adequate stoichiometric amounts of oxygen to assure complete combustion are determined by measuring any variations of the mass flow rate of the fuel gas and/or undesired chemical and effecting a corresponding adjustment of an air flow control valve to admit a predetermined amount of pressurized air and/or atmospheric air to the flaring tip. A Coanda-effect body is positioned proximate the open end of the flare stack to improve the mixing of the air feedstream with atmospheric air and combustible components and to elevate the heat of the flame above the metal structural elements that control air flow at the top of the flare stack.

High-pressure air is discharged in the form of jets moving at a high velocity from nozzles () mounted on a ring manifold () that encircles the flare stack () at a predetermined distance below the flare tip (), the upper portion of the flare stack being surrounded by an exterior shield () that is provided with internal guide vanes () at the top portion and perforated with air passages () at the bottom portion. The high-velocity air movement in the annular space creates a low pressure zone that in turn induces a larger volume of air from the atmosphere to enter the annular space between the shield and stack where it rises to the flame zone (), thereby lifting the flame and enhancing turbulent air, fuel and waste gas mixing in the flame zone to minimize or eliminate smoke.

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Dhahran, Saudi Arabia

Mazen Mashhour