Hydrocarbon Processing - April 2022 - GP-23

PLANT DESIGN, ENGINEERING, CONSTRUCTION
AND COMMISSIONING
Soft startup of best practices
for commissioning of amine plants
A. AL-QAHTANI, Saudi Aramco, Dhahran, Saudi Arabia; and
A. AL-WARTHAN and M. AL-SUBAIE, Saudi Aramco, Jubail, Saudi Arabia
The startup and commissioning of
hydrocarbon plants can present unique
challenges that, if not anticipated and addressed
in the pre-commissioning and
commissioning periods, will inhibit plant
startup and increase the difficulty of
achieving product specifications in a timely
manner. This article provides details on
potential multiple challenges during commissioning,
as well as a method to avoid
these challenges by applying a soft startup
concept on a massive scale. The acceptance
criteria and successful results of the
soft startup concept are detailed here.
Plant A sought to avoid or reduce the
common commissioning challenges of
a new amine system (e.g., gas treatment
facility), including foaming, the presence
of unwanted debris or materials in piping
and vessels, etc. To ensure the short- and
long-term reliability of an amine system
facility, Plant A elected to implement a soft
startup concept on a massive scale, where
the amine circuits are filled completely
with pure demineralized water (rather
than amine), then pressurized by nitrogen
(rather than fuel gas) up to the operating
pressure. This was completed for multiple
safety and reliability reasons to:
* Test system tightness with a
safer medium (nitrogen,
as compared to fuel gas)
* Debug the associated process
control and emergency shutdown
(ESD) systems
* Test the functionality and reliability
of all rotating equipment
* Clean the system of any remaining
debris and suspended solids prior to
charging with expensive solvent into
the unit
* Limit the potential for future
foaming incidents.
During the soft startup, circulation is
started in both cold and hot modes to enSour
feed
gas
Lean amine
Flash drum
Feed filter separator
FIG. 1. Typical PFD for an acid gas removal unit.
Gas Processing & LNG | MARCH/APRIL 2022 23
booster pump
Reclaimer
for DGA
sure that all debris and suspended solids
are removed from the pipe walls, fittings,
valves and other equipment and vessels,
and the debris and suspended solids are
caught by the strainers and filters. This
approach was successfully utilized in the
other amine units.
Amine system process description-
acid gas removal unit. The gas enters the
treating train through the inlet filter separator.
The separator is provided to remove
any particulate matter or traces of liquids
that may be received with the incoming
gas. Without a spare separator, a bypass
valve (sized for full flow) is installed to allow
maintenance servicing of the separator.
The gas coming from the inlet filter is
fed to the amine contactor for carbon dioxide
(CO2
) removal. The contactor is a
tray column divided in two sections. The
bottom amine absorber section consists of
trays. The lean amine is fed to the top tray
and the rich amine is withdrawn from the
Sweet wet gas
Condenser
Filters
Wash water
pump
Circulation
pump
Contactor
Off-gas
Lean/Rich
exchanger
Reboiler
Lean cooler
Regenerator
Reflux pump
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.
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
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
Acid gas
to SRU
Hydrocarbon Processing - April 2022

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