Page 91 - Petroleum and Gas Field Processing

wire-mesh extractors are capable of removing about 99% of the
10-mm and larger liquid droplets. It should be noted that this
type of mist extractor is prone to plugging. Plugging could be
due to the deposition of paraffin or the entrainment of large
liquid droplets in the gas passing through the mist extractor (this
will occur if the separator was not properly designed). In
such cases, the vane-type mist extractor, described next, should
be used.
2. Vane Mist Extractor: This type of extractor consists of a series of
closely spaced parallel, corrugated plates. As the gas and
entrained liquid droplets flowing between the plates change flow
direction, due to corrugations, the liquid droplets impinge on the
surface of the plates, where they coalesce and fall down into the
liquid collection section.
3. Centrifugal Mist Extractor: This type of extractor uses
centrifugal force to separate the liquid droplets from the gas.
Although it is more efficient and less susceptible to plugging than
other extractors, it is not commonly used because of its
performance sensitivity to small changes in flow rate.

Inlet Diverters
Inlet diverters are used to cause the initial bulk separation of liquid and
gas. The most common type is the baffle plate diverter, which could be in
the shape of a flat plate, a spherical dish, or a cone. Another type, is the
centrifugal diverter; it is more efficient but more expensive. The diverter
provides a means to cause a sudden and rapid change of momentum
(velocity and direction) of the entering fluid stream. This, along with the
difference in densities of the liquid and gas, causes fluids separation.

Wave Breakers
In long horizontal separators, waves may develop at the gas–liquid
interface. This creates unsteady fluctuations in the liquid level and would
negatively affect the performance of the liquid level controller. To avoid
this, wave breakers, which consist of vertical baffles installed perpendicular
to the flow direction, are used.

Defoaming Plates
Depending on the type of oil and presence of impurities, foam may
form at the gas–liquid interface. This results in the following serious

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