Page 103 - Petroleum and Gas Field Processing

2. Determine C d : Assume C d ¼ 0.34, Using Eq. (2),

1=2
o
u ¼ 0:01186 g d m
g C d
1=2
53:03 3:708 100
¼ 0:01186
3:708 0:34
ft
u ¼ 0:7418
s
g d m u 3:708 100 0:7418
Re ¼ 0:0049 ¼ 0:0049 ¼ 103:67
g 0:013
3 24
C d ¼ 0:34 þ þ
Re 0:5 Re
3 24
¼ 0:34 þ þ ¼ 0:866
0:5
ð103:67Þ 103:67
3. Repeat the above steps using the calculated value of C d to obtain
a new value of c d and continue until convergence. The final value
of c d is 1.1709.
4. Check for gas capacity constraint, Eq. (9):
1=2

2 TZ g C d
D ¼ 5; 058Q g
P ð Þ d m
g
o
1=2
520 0:84 3:708 1:1709

¼ 5058 15
1000 53:03 3:708 100
2
D ¼ 983:246;
therefore,
D min ¼ 31:357 in: ðE1Þ
This is the minimum allowable vessel diameter for separation of
oil droplets down to 100 mm.
5. Check for liquid capacity (retention time constraint), Eq. (13):
2
D H ¼ 8:565Q t ¼ 8:565 3000 3 ¼ 77; 805 ðE2Þ
o
6. Select values for D greater than 31.357 in. and calculate the
corresponding values of H from Eq. (E2) and the corresponding
values of L s from Eq. (14) for D < 36 or Eq. (15) for D > 36. The
results are as follows:
From the results in the table, the first two diameters provide
slenderness ratios within the commonly used range; therefore,

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