Page 294 - Petroleum and Gas Field Processing

Figure 12 Equilibrium solvent loadings.

200 psia, the loading (mol H 2 S/gal solvent) of MEA (20% solution) is
about 11.5, and at the same time, sulfolane (physical solvent) is about 18
and sulfinol (which is a mixed solvent) is about 19.

11.6 DIRECT CONVERSION PROCESSES

There are many processes used to convert H 2 S to sulfur; however, our
discussion here is limited to those processes applied to natural gas.
Generally, H 2 S is absorbed in an alkine solution containing an oxidizing
agent which converts it to sulfur. The solution is regenerated by air in a
flotation cell (oxidizer). The following processes are used for this purpose.

11.6.1 Stretford Process

The absorbing solution is dilute Na 2 CO 3 , NaVO 3 , and anthraquinone
disulfonic acid (ADA). The reaction occurs in four steps:
H S þ Na CO ¼ NaHS þ NaHCO 3 ð15Þ
2
3
2

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