Serving the Oil & Gas Industry Since 1980

Gas Deaerators

EN-FAB deaerators are used to separate and remove entrained air and gas from petroleum and other liquid products, especially in metering applications.

Since elimination of gas and air is essential to metering accuracy, the EN-FAB deaerator is a necessary part of any metering system wherever there is a possibility that air can be introduced or entrained into the system.

EN-FAB, Inc. deaerators are used for the elimination of free air or gas from hydrocarbon liquid flowing under pressure through piping. It is particularly applicable where the liquid flow is being metered.

Basic Operation Principles of the EN-FAB Deaerator

The Gas Deaerator can be a horizontal or vertical vessel depending on the type of application and space limitations. The vessel is sized to have sufficient retention time for the gas/air bubbles to rise to the top of the vessel. To assist this gas/air removal, the interior of the Deaerator will have a series of inclined steel scrubber plates to collect and segregate these bubbles. The bubbles then coalesce and pass to the top of the vessel.

General Theory of Differential Gravity Separation of Particles

Gravity clarification permits removal of particles which exhibit density differences from their carrier fluid. Separation is accomplished by detaining or slowing down the flow stream for a sufficient amount of time. This permits particles to separate out. The particles (bubbles) which rise to the surface of the liquid possess "rise rate" and have negative velocities. Stokes Law establishes the theoretical terminal velocities of the rising bubbles. The larger the size of the discrete particle, the higher the efficiency of separation.

Vp = G(dp - dc) D

18n

where Vp = rising velocity of discrete particle

G = gravity constant

n = absolute viscosity of carrier fluid

dp = density of discrete particle

D = diameter pf discrete particle

dc = density of carrier fluid

Horizontal Versus Vertical

For Deaerators with identical dimensions, a horizontal unit performs more efficiently than the vertical unit. This is achieved because the bubble has a longer horizontal distance to travel and a shorter vertical distance to overcome. This performance is further enhanced by parallel plates to create laminar flow. Slots in scrubber plates, additionally provide an escape route for the bubbles. In a vertical unit, bubbles travel upwards, counter flow to the liquid carrier, where they are expelled through a pneumatic float actuated control valve commonly referred to as an air eliminator valve.

Installation

The Deaerators should be installed on a level foundation and as close to the meter as possible. The discharged vapor from the eliminator valve should be piped to a convenient and safe point. A suitable flame arrestor should be installed at the end of the vapor eliminator discharge piping.