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Example 2
A natural gas is flowing at 100 MMSCFD at 1000 psia and 100 F. It
contains 2 mol% CO 2 and 1.9 mol% H 2 S. It is being treated by the amine
process using DEA. The outlet gas contains no acid components. Calculate
the flow rate of DEA required and the tower diameter and height.
Solution
Total acid gas ¼ 2 þ 1:9 ¼ 3:9 mol%
Amine flow rate (q Am Þ¼ 126X AG
q Am ¼ 126ð3:9Þ¼ 491:4gpm
The tower diameter is
560ð0:85Þð100Þ 1=2
2
d ¼ 504 g C d
1000 l g
Assuming the drag coefficient (C d ) is 0.7,
PM ð1000Þð16Þ lb
¼ ¼ ¼ 3:14 3
g
2RT ð0:85Þð10:7Þð560Þ ft
where P is the pressure and M is the molecular weight. Assuming an average
molecular weight of natural gas the same as methane (16), then
¼ water at 100 F
L
lb
¼ 65:1 3
ft
3:14
g
¼ ¼ 0:05068 ¼ 0:0507
l g 65:1 3:14
2 1=2
d ¼ 504ð47:6Þ½0:0507ð0:7Þ
then
d ¼ 67:2in: ¼ 5:6ft
Use 24 trays with a spacing of 24 ft with a height of (24)(2) ¼ 48 ft.
11.5.2 Hot Potassium Carbonate Process
In this process, hot potassium carbonate (K 2 CO 3 ) is used to remove both
CO 2 and H 2 S. It can also remove (reversibly) COS and CS. It works best
Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.
