Hydrocarbon Processing - August 2022 - 70

Plant Design, Engineering, Construction and Commissioning
the amine contactor by booster pumps.
Before being fed to the contactor, the lean
amine is cooled through the lean/rich
amine exchanger and the lean amine cooler.
The lean amine circulation pumps boost
the pressure and return the lean amine to
the amine contactor. Pumps route a fraction
of the circulating lean amine (~15%)
to the precoat filter package, and filtered
amine is rejoined to the lean amine flow.
The amine reclaimer is provided to
FIG. 2. Frequent strainer cleaning for amine System A.
A continuous make-up of fresh reverse
osmosis water is fed to the top of the section,
while excess water is drained from
the column water wash chimney tray to
the rich amine flash drum. The outlet
for the wet sweet gas from the top of the
amine contactor is routed out of the gas
treating train to the natural gas liquids
(NGL) recovery unit.
Rich amine from the contactor bottom
FIG. 3. The progression of water clarity by the
samples collected from amine System A.
is fed to the rich amine flash drum, a horizontal
vessel with a top-mounted vertical
absorber equipped with random packing.
The hydrocarbon gases dissolved in
the rich amine are flashed off, washed
through the absorber and routed to the
thermal oxidizer. As the flashed gases pass
through the absorber, any amine entrainment
is removed by the counter flow of
the water withdrawn from the amine contactor
top section. The rich amine coming
from the flash drum is heated up through
the lean/rich amine exchangers and fed to
the amine stripper.
The stripper is a trays column with
FIG. 4. Dirt accumulation in pump strainers.
from the bottom of the tower. The upper
section of the contactor comprises three
trays and is used as a water washing system
to absorb any amine entrained in the
gas from the bottom absorber section.
The second pass reverse osmosis water is
circulated around the trays by pumps.
70 AUGUST 2022 | HydrocarbonProcessing.com
two once-through exchangers that take
feed from the column bottom chimney
tray. Heat for the amine stripper reboilers
is supplied from the low-pressure hot
water system. The gases from the top of
the stripper are cooled in the amine stripper
overhead condenser and water is condensed
in the reflux drum. The acid gas is
routed to the CO2
compression unit. Any
organic phase present will be separated in
the reflux drum and manually discharged
to the wet hydrocarbon burn pit.
The reflux pumps return the condensed
water as reflux back to the stripper top tray
and, during the regeneration cycle, partially
to the amine reclaimer. The lean amine
from the stripper bottom is routed toward
periodically regenerate the circulating
amine. A fraction of the circulating lean
amine from the booster pumps (~1% of
the total amine pumped flowrate) is fed
to the amine reclaimer. The reclaimer operates
at 360°F (182°C) and controls the
amine solution boiling temperature by an
adequate flowrate of reflux water from the
amine stripper reflux pumps. Amine and
water are recovered to the stripper as vapors
coming from the top of the reclaimer,
while degraded amine components are left
on the vessel bottom. This sludge pond
also receives the amine slurry from the
amine precoat filters. The acid gas removal
process configuration is shown in FIG. 1.
Amine system process description-
acid gas enrichment
unit. The wet
acid gas is first cooled in a cooling water
chiller and then enters an inlet separator
to remove liquid hydrocarbons from the
gas stream. The acid gas then enters the
bottom of the contactor trayed column
and flows upward through the absorber in
intimate countercurrent contact with the
selective amine solution, where the amine
selectively absorbs hydrogen sulfide (H2
S)
acid gas constituents from the gas stream.
Before leaving the contactor, the CO2
gas
passes through a water wash section.
The rich amine solution is sent from
the bottom of the contactor via the rich
amine pump to the lean-rich amine heat
exchanger, before entering the top of the
stripper column. A part of the absorbed
acid gases will be flashed from the heated
rich solution on the top tray of the stripper.
The remainder of the rich solution
flows downward through the stripper in
countercurrent contact with vapor generated
in a steam reboiler. The reboiler vapor
(primarily steam) strips the acid gases
from the rich solution.
The acid gas and the steam leaving the
top of the stripper pass through a condenser,
where the major portion of the steam is
condensed and cooled in an air cooler. The
http://www.HydrocarbonProcessing.com
Hydrocarbon Processing - August 2022

Table of Contents for the Digital Edition of Hydrocarbon Processing - August 2022
