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Figure 6.1 – Scheme horizontal separator

At the crude entrance there is a baffle slug catcher that will
reduce the effect of slugs (Large gas bubbles or liquid plugs).
However some turbulence is desirable as this will release gas
bubbles faster than a laminar flow.
At the end there are barriers up to a certain level to keep
back the separated oil and water. The main control loops are the oil
level control loop (EV0101 20 above) controlling the oil flow out
of the separator on the right, and the gas pressure loop at the
top.(FV0105 20 above) These loops are operated by the Control
System [19]. An important function is also to prevent gas blow-by
which happens when low level causes gas to exit via the oil output
causing high pressure downstream. There are generally many more
instruments and control devices mounted on the separator. These
will be discussed later.
The liquid outlets from the separator will be equipped with vortex
breakers to reduce disturbance on the liquid table inside. This is
basically a flange trap to break any vortex formation and ensure
that only separated liquid is tapped off and not mixed with oil or
water drawn in though these vortices. Similarly the gas outlets are
equipped with demisters, essentially filters that will remove liquid
droplets in the gas.

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