Category: Two Phase Oil and Gas Separation

Two Phase Vertical Separators Sizing

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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 …

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Two Phase Horizontal Separators Sizing

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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 …

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Two Phase Separator Re-entrainment

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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 …

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Two Phase Separator Retention Time

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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 …

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Two Phase Separator Drop Size

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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 …

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Two Phase Separator Settling

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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 …

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Liquid Carryover and Gas Blowby

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Liquid carryover and gas blowby are two common operating problems. Liquid carryover occurs when free liquid escapes with the gas phase and can indicate high liquid level, damage to vessel internals, foam, improper design, plugged liquid outlets, or a flow rate that exceeds the vessel’s design rate. Gas blowby occurs when free gas escapes with …

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Sand

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Sand can be very troublesome in separators by causing cutout of valve trim, plugging of separator internals, and accumulation in the bottom of the separator. Special hard trim can minimize the effects of sand on the valves. Accumulations of sand can be alleviated by the use of sand jets and drains. Plugging of the separator …

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Paraffin

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Separator operation can be adversely affected by an accumulation of paraffin. Coalescing plates in the liquid section and mesh pad mist extractors in the gas section are particularly prone to plugging by accumulations of paraffin. Where it is determined that paraffin is an actual or potential problem, the use of plate-type or centrifugal mist extractors …

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