# Category: Two Phase Oil and Gas Separation

In vertical separators, a minimum diameter must be maintained to allow liquid drops to separate from the vertically moving gas. The liquid retention time requirement specifies a combination of diameter and liquid volume height. Any diameter greater than the minimum required for gas capacity can be chosen. Figure 4-15 shows the model used for a […]

For sizing a horizontal separator it is necessary to choose a seam-toseam  vessel length and a diameter. This choice must satisfy the conditions  for gas capacity that allow the liquid drops to fall from the gas to the liquid volume as the gas traverses the effective length of the vessel. It must also  provide sufficient […]

Re-entrainment is a phenomenon caused by high gas velocity at the gas-liquid interface of a separator. Momentum transfer from the gas to the liquid causes waves and ripples in the liquid, and then droplets are broken away from the liquid phase. The general rule of thumb that calls for limiting the slenderness ratio to a […]

To assure that the liquid and gas reach equilibrium at separator pressure a certain liquid storage is required. This is defined as “retention time” or the average time a molecule of liquid is retained in the vessel assuming plug flow. The retention time is thus the volume of the liquid storage in the vessel divided […]

The purpose of the gas separation section of the vessel is to condition the gas for final polishing by the mist extractor. From field experience it appears that if 100-micron drops are removed in this section, the mist extractor will not become flooded and will be able to perform its job of removing those drops […]

In the gravity settling section the liquid drops will settle at a velocity determined by equating the gravity force on the drop with the drag force caused by its motion relative to the gas continuous phase. The drag force is determined from the equation: where FD = drag force, Ib CD = drag coefficient A […]

Horizontal separators are smaller and less expensive than vertical separators for a given gas capacity. In the gravity settling section of a horizontal vessel, the liquid droplets fall perpendicular to the gas flow and thus are more easily settled out of the gas continuous phase. Also, since the interface area is larger in a horizontal […]