Hydrocarbon Processing - April 2022 - GP-15

SPECIAL FOCUS: GREEN TECHNOLOGIES
ally found in the vapor phase. Due to the
increased carrying capacity that hydrogen
sulfide (H2
S can
S) provides to natural gas,
its presence in the transported gas mixture
helps with transporting elemental
sulfur. Compared to methane, H2
carry more sulfur by three or four more
orders of magnitude. Consequently, the
probability of sulfur deposition in oil and
gas processing facilities is increased.
The desublimation of elemental sulfur
at certain pressure and temperature conditions
is a major cause for deposition.
Usually, the low concentration of elemental
sulfur-within the parts-per-billion
range-makes it more challenging to detect.
In some cases, elemental sulfur desublimates
intermittently at certain locations
within the plant, causing difficulties
in tracking the root causes of the problem.
In addition to elemental sulfur solubility,
the oxidation of sulfur compounds
could also be a major cause for elemental
sulfur deposition. Testing of the demineralized
water (in a liquid-ring compressor)
indicates that the dissolved oxygen
is within the acceptable parts-per-million
range. Normally, oxidation of sulfur compounds
like H2
S leads to the production
of sulfur in the elemental form at certain
pressure and temperature conditions.
However, the source of oxygen is not
limited to that in the demineralized water,
as it could be air entering the system
through leaks, or it could involve the
availability of oxygen within the gas mixture
transported to the FGRS. Operating
the purge gas below the minimum safety
requirements can be a major contributor
of exposing oxygen in the system.
Also, part of enhancing FGRS reliability
is to segregate flare headers with power
operated emergency isolation valves
(ZVs) should any upset occur in the facility.
The FGRS is designed to recover
the normal continued flaring; during an
upset, the FGRS will be interrupted, resulting
in a trip. Therefore, as part of reliability
enhancement, the team proposed
segregating feed ZV to the FGRS, along
with sending a signal to close it in case
the pressure in one of the flare headers
increases near to the tipping point.
Prior to any change in the flare and relief
systems, such as installing a flare gas
recovery package, a study of full flare and
relief systems should be carried out. Installing
a flare gas recovery system could
change the constant backpressure in the
MAHDI ALDAJANI is a Flare and
Relief Systems Engineer at Saudi
Aramco. He has 10 yr of experience
with Saudi Aramco, working in
several Saudi Aramco facilities in
support of operations and on
detailed design and construction
activities on several projects. Mr. Aldajani earned a BS
degree in chemical engineering from KFUPM.
ABDULLMAJEED AL-SANAD is a
Process Engineer at Saudi Aramco's
Process and Control Systems
Department, within the Flare and
Relief Systems Group. He has 6 yr
of experience, which includes
company operations and project
support. Mr. Al-Sanad has also participated in a flaring
minimization program that included several aspects
such as purge gas optimization studies and FGRS
evaluations. He earned a BS degree in chemical
engineering from KFUPM.
MOHAMMED AL-MAHMOOD
is a Process Engineer at Saudi
Aramco's Process and Control
Systems Department, within the
Energy Transition Engineering
Group. He has 6 yr of experience
with Saudi Aramco, which includes
company operations and project support. Mr.
Al-Mahmood has also participated in the
commissioning and process stabilization of an FGRS
in one of the company's gas operation facilities. He
has also helped to evaluate FGRS feasibility and
energy consumption to identify reliable FGRS
applications. Mr. Al-Mahmood earned a BS degree in
chemical engineering from Oklahoma State University.
Gas Processing & LNG | MARCH/APRIL 2022 15
headers, which would affect the limit on
PZVs allowable backpressures. Having
the FGRS could also develop new critical
overpressure scenarios that would
need to be addressed. Further, in many
applications, processes are
equipped
with continuous vent-to-flare systems,
either in the process equipment or in
the seal gas of the compression systems.
Even small changes in operating pressures
of the flare headers could lead to
process interruptions from these services.
Overall, any proposed changes in
flare and relief system operations should
be first assessed with appropriate studies
on these systems. GP
ABDULAZIZ H. AL-TIJANI is an
Engineering Specialist at Saudi
Aramco's Process and Control
Systems Department in Dhahran,
Saudi Arabia. He supports company
operations and project design,
mainly in flare and relief systems
and in flare gas recovery applications. Mr. Al-Tijani
also supports Saudi Aramco and JV oil and gas
operational facilities, pipelines and process
simulations, as well as various phases of projects. He
earned a BS degree in chemical engineering from
King Fahd University of Petroleum and Minerals
(KFUPM), and an MS degree in oil and gas surface
facilities from KFUPM (in partnership with IFP).
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Hydrocarbon Processing - April 2022

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