Refining Processes Handbook - 2020 - 157

2020 REFINING PROCESSES HANDBOOK
PROCESS CATEGORIES

COMPANY INDEX

DESULFURIZATION

Amine Treating

Sweet gas

(8)

Application: Bechtel Hydrocarbon Technology Solutions Inc. (BHTS) offers a
complete suite of sulfur block technologies, including amine treating. Amine treating
removes acid gases [hydrogen sulfide (H2S) carbon dioxide (CO2 ) and carbonyl sulfide
(COS)] from fuel gas headers, hydrotreaters (DHT, NHT, etc.), coker off-gases and LPG.
Depending on the service, the amine used includes MEA, DEA, DGA, DIPA, MDEA and
proprietary activated amine, any of which BHTS will evaluate.
Description: The typical sour gas stream is saturated with hydrocarbons, so a sour
KO drum (1) removes entrained liquid before entering the amine absorber (2), where
the amine flows counter-currently. The amine absorbs acid gas, and the sweet gas is
returned to the refinery through a KO drum (3), which recovers entrained amine to
reduce carry-over losses and OPEX.
The amine rich in acid gases is flashed to about 5 psig (or flare header pressure)
(4) to remove entrained hydrocarbons and allow phase separation from light
hydrocarbons. Flashed vapors are flared or recovered by a wet gas compressor.
Recovered hydrocarbon liquids are typically sent to the refinery slop-oil system.
The rich amine is then pumped (5) through a filtration system (not shown) to
remove particulates and entrained hydrocarbons to minimize downstream erosion,
fouling and loss of performance, before being pre-heated (6). It then enters the
regenerator (also called a stripper, 7), in which vapor, generated in the reboiler (11),
strips the acid gases from the amine. From the regenerator bottoms, the lean amine is
pre-cooled (6) and pumped (12) through the lean-amine coolers (13), which can be a
combination of air- and water-cooled exchangers, back to the absorber.
The regenerator overhead gas is cooled (8), and reflux (sour water) is recovered
(9) and pumped (10) back to the regenerator. The amine acid gas is typically then sent
to a sulfur recovery unit (SRU). Water balance is critical to meeting specifications, and
is maintained by either purging sour water reflux or adding water to the regenerator
overhead (acting as an ammonia wash), which benefits the SRU.
Advantages: Bechtel's amine treating units can reduce contaminant acid gases
to the standard US fuel gas specification of 160 ppmv H2S or lower. With specialty
amines, concentrations as low as 10 ppmv can be reached.

Amine acid gas

Fresh water makeup

(3)

(9)

(13)

(12)
(10)

(2)

Flash gas

(6)

(7)

Sour water purge
LP steam

Sour gas

(4)
(1)

(11)

(5)

Utilities: typical per gal of feed
Electricity, kWh	
Steam (LP), lb/gal of amine circulation	
Water, cooling (25°F), gal	
Fuel (absorbed), Btu	

0.01
1.0
3.8
0

Installations: This process has been used in thousands of units worldwide
to produce low-sulfur and low-CO2 process streams.
Licensor: Bechtel Hydrocarbon Technology Solutions Inc.
Website: www.bechtel.com/bhts
Contact: bhts@bechtel.com

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Refining Processes Handbook - 2020

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