Page 97 - Petroleum and Gas Field Processing

Figure 17 Outline of the calculated procedure for determining the gas capacity of
GOSPs.

where D is the internal diameter of the separator in inches, and then
solving for D, we obtain
1=2
2 TZ g C d 2
D ¼ 5:058Q g in: ð9Þ
P ð o g Þ d m
Equation (9) provides the minimum acceptable diameter of the separator.
Larger diameters yield lower gas velocities and, thus, better separation of
the oil droplets from the gas. Smaller diameters, on the other hand, result
in higher gas velocities and, therefore, the liquid droplets will be carried
over with the gas.
A summary of the steps involved in the calculation of the gas
capacity of a gas–oil separator is outlined in Figure 17.
In solving Eq. (9), the value of the drag coefficient C d must first be
determined. C d is related to the Reynolds number, Re, according to the
following formula [4]:
3 24
C d ¼ 0:34 þ 0:5 þ ð10Þ
Re Re
where the Reynolds number is given by
g d m u
Re ¼ 0:0049 ð11Þ
g
where g is the gas viscosity.

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