Page 315 - Petroleum and Gas Field Processing

T ¼ 75 65 ¼ 10 F

Using Eq. (2),
2335 W
10 ¼
32:04ð100 W Þ
Therefore, W ¼ 12.07%
Required methanol in water ¼ (0.1207)(2000) ¼ 241.4 lb/day
Pounds of methanol in vapor ¼ (0.95)(12.07) ¼ 11.47 lbs/MMSCF
¼(11.47)(10) MMSCF/day
¼ 114.7 lbs/day
Methanol dissolved in condensate ¼ (0.005)(300) lbs/bbl 700 bbl/day
¼1050 lbs/day
Total amount of methanol ¼ 241.4 þ 114.7 þ 1050 ¼ 1406 lbs/day
From the results, we see that 1050 lbs of methanol (75% of the total) are
dissolved in the condensate and thus do not contribute to the treatment.
Such treatment is, therefore, economically unacceptable. It is evident that
the condensate must be separated first before the treatment.

12.3.3 Dehydration Methods

The most common dehydration methods used for natural gas processing
are as follows:
1. Absorption, using the liquid desiccants (e.g., glycols and
methanol)
2. Adsorption, using solid desiccants (e.g., alumina and silica gel)
3. Cooling/condensation below the dew point, by expansion and/or
refrigeration

This is in addition to the hydrate inhibition procedures described earlier.
Classification of dehydration methods is given in Figure 4 [3].

12.4 ABSORPTION (GLYCOL DEHYDRATION PROCESS)
12.4.1 Basic Principles

The basic principles of relevance to the absorption process are as follows:
1. In this process, a hygroscopic liquid is used to contact the wet
gas to remove water vapor from it. Triethylene glycol (TEG) is
the most common solvent used.

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.