American Oil and Gas Reporter - May 2020 - 59

SpecialReport: Production & Processing
The technology was developed to mitigate many of the issues associated with
the REDOX process. It retains the chelated
iron pseudo-catalyst, but introduces three
critical changes:
· A novel chelant that is resistant to
degradation, thereby imparting a longer
circulation time, lower makeup rates, and
lower oxalate formation;
· Bespoke defoaming surfactants and
wetting agents to promote sulfur settling,
minimize chemical loss in the filter and
destroy emulsions; and
· Advanced process control techniques, including machine learning and
artificial intelligence, as well as proprietary
instrumentation to monitor and control
the extent of the reaction, thereby increasing
chelant life and optimizing operation.
Maintaining the optimal regenerative
capabilities of the system (thereby minimizing OPEX) requires maintaining the
extent of the reaction of the two chemical
steps within a narrow range. Achieving
this level of control has required developing an intelligent, tiered control schema
that employs a programable logic controller, a local computer to perform complex calculations on site and cloud computing that can perform extended calculations to maintain system health.

regardless of H2S concentration, flow
rate or pressure, any sour gas stream
between the wellhead and the pipeline,
including tail gases, can be treated.
Direct treatment of sour gas can be
done either at the wellhead using a
small skid-based unit, or at a gathering
facility with a custom-designed plant.
Secondary treatment (i.e., post-amine
plant separation) can be performed on

tail gases.
If compression exists, applications at
high pressure-either direct or after amine
treatment to concentrate the sour components into acid gas (H2S and CO2)-
can provide an economical alternative
to acid gas injection, Claus sulfur recovery, or other technologies to remove
or recover H2S.
Direct-treat applications of the tech-

Process Flow
As shown in Figure 1, the process
begins with sour gas flowing through a
vapor-liquid separator and inlet filter
coalescer, which remove any hydrocarbon
droplets. The clean, sour gas then flows
into a contact tower, where it contacts
the chelant chemistry. The H2S-free gas
then flows out of the contactor and
through a sweet gas vapor-liquid separator
and outlet filter coalescer. The chemistry
containing elemental sulfur solids flows
to the regenerator, where air is added
and the ferrous ion (Fe2+) is oxidized
to ferric (Fe3+) cation. The regenerated
liquid stream flows to a settling tank,
where the sulfur is settled and sent to
filtration to remove sulfur and return
the liquid chemistry back to the settling
tank. Clean chemistry is pumped back
into the contactor.
Since the new REDOX process completely converts H2S to elemental sulfur

MAY 2020 59
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American Oil and Gas Reporter - May 2020

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