Hydrocarbon Processing - December 2020 - GP-24

SPECIAL FOCUS: PLANT DESIGN AND PROCESS CONTROL

tion with CO2 levels, contactor design
and tray ratings.
Spray flow usually happens at the top
trays in an amine unit contactor. This
phenomenon occurs when low liquid
loads of amine solvent on trays lead to
liquid aerosolization into the treated
outlet gas. This causes constant low-tomedium levels of amine solvent losses
that can, in many cases, go unnoticed. To
move the flow regime from spray mode
to froth mode (to the left of the spray
regime in FIG. 7), it was recommended
to increase the amine solvent flowrate
and raise the liquid load on the contactor trays. FIG. 7 shows a diagram of flow
regimes in a trayed tower based on liquid
and vapor flowrates. The froth regime
area represents the most ideal conditions
for a tray-based amine unit contactor.
Evaluation of the regenerator was also
performed and revealed that a flow control valve in the reflux overhead for manual regenerator operation was not present,
which may have led to instabilities. The
regenerator, when operating in automatic
mode, has a smoother and more effective
control because more than one variable
is manipulated at a time. Additionally, no
temperature control was present in the reflux overhead.
Findings, recommendations and
remarks. After assessing each aspect

of the process related to startup, it was
concluded that no single factor could be
resolved to allow the plant to start up suc-

Spray entrainment

cessfully. A number of areas were identified that contributed to foaming, process
fluctuations and other detrimental effects
that hindered the plant from reaching its
design operating conditions. The design
of the contactor tower at the amine unit
was sensitive to foaming and fluctuations
compared to other contactors. Inadequate
operational control capabilities, insufficient lean amine flowrate to the contactor
causing a spray flow regime, low-to-moderate levels of contamination (including
methanol ingression), and an ineffective
activated carbon were all major causes of
amine unit shutdowns. The root causes of
foaming were likely low-to-moderate levels of gas-phase contaminant ingression
with the feed gas, recycled streams from
downstream processes and materials,
and chemical incompatibility with several materials. Contaminants exposed to
regenerator temperatures may also have
formed more aggressive foam promotors,
leading to high foaming tendency in the
reflux accumulator.
In any case, several actions taken in
parallel were necessary to successfully
combat the startup challenges. The plant
was eventually able to start up and operate
at design conditions after addressing the
concerns identified in this evaluation. Automated control schemes and better operating practices, as well as compatible materials, were used to stabilize the process and
remove contaminants (some promoting
foam formation). New carbon materials,
antifoam and amine filters with no adverse

Jet flood

Vapor rate

Spray regime

Froth regime

Downcomer choke
and backup

Incipient weep
Acceptable weep
Dump point

Liquid rate

FIG. 7. Tray flow regime diagram. Diagram adapted from Kister, H. Z., Distillation Design,
McGraw-Hill, 1992.

24

NOVEMBER/DECEMBER 2020 | GasProcessingNews.com

compatibility effects were recommended.
A more coordinated and careful approach to startup was taken. The front
end of the plant was slowly and cautiously
started, in terms of feed gas flow introduction, after new control solutions were
installed. LNG processes can be difficult
to operate and maintain, and startup can
be even more cumbersome due to the
number and variety of tasks involved. Addressing each task in a systematic and organized way is vital for an on-time and onspecification LNG production startup.
Despite all the changes made, the most
important factor in achieving stable startup operation was a unified and communicative environment among operators
and engineers at the plant. Situations may
arise unexpectedly, but proper training
and communication can help resolve upsets before they grow out of control. GP
DAVID ENGEL has more than 25 yr
of industrial experience in a variety
of chemical engineering and
chemistry areas. He is the inventor
in 21 US patents and the author of
a number of technical and scientific
papers. Dr. Engel has developed
business and technology for Eastman Kodak, Eli Lilly,
Pentair, General Electric and Sulphur Experts
worldwide. He has specialized in chemical engineering,
process chemistry, optimization and contaminant
removal technologies. He is the Managing Director of
Nexo Solutions and the Technology Leader for Exion
Systems. He holds a BS degree in industrial chemistry,
a MS degree in chemistry and a PhD in organic
chemistry. He is also Six Sigma and Project
Management certified. Dr. Engel is President of the
American Filtration Society, Southwest Region; and
a member of the Gas Processors Association Technical
Section M, in addition to a member of the boards of
directors at several companies.
CODY RIDGE is a Lead Process
Engineer at Amine Optimization
Company and a Chemical Engineer
from Texas Tech University in
Lubbock, Texas. He is responsible for
field engineering and technology
development with Amine
Optimization. Mr. Ridge has worked as an operator and
process engineer in the Permian Basin.
SCOTT WILLIAMS is a Process
Engineer at Amine Optimization.
He has industry experience in a
number of projects in oil and gas,
petrochemical, chemical and water
treatment applications. As part of
the Amine Optimization engineering
group, Mr. Williams is responsible for technical design
and solutions development in engineering and
technology applications. He also provides support for
analytical and specialized service projects. His recent
work has been focused on amine unit contamination
control, process stability and energy reduction. Mr.
Williams holds a BS degree in chemical and biological
engineering from the University of Colorado at Boulder.


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Hydrocarbon Processing - December 2020

Table of Contents for the Digital Edition of Hydrocarbon Processing - December 2020

Contents
Hydrocarbon Processing - December 2020 - Intro
Hydrocarbon Processing - December 2020 - Cover1
Hydrocarbon Processing - December 2020 - Cover2
Hydrocarbon Processing - December 2020 - Contents
Hydrocarbon Processing - December 2020 - 4
Hydrocarbon Processing - December 2020 - 5
Hydrocarbon Processing - December 2020 - 6
Hydrocarbon Processing - December 2020 - 7
Hydrocarbon Processing - December 2020 - 8
Hydrocarbon Processing - December 2020 - 9
Hydrocarbon Processing - December 2020 - 10
Hydrocarbon Processing - December 2020 - 11
Hydrocarbon Processing - December 2020 - 12
Hydrocarbon Processing - December 2020 - 13
Hydrocarbon Processing - December 2020 - 14
Hydrocarbon Processing - December 2020 - 15
Hydrocarbon Processing - December 2020 - 16
Hydrocarbon Processing - December 2020 - 17
Hydrocarbon Processing - December 2020 - 18
Hydrocarbon Processing - December 2020 - 19
Hydrocarbon Processing - December 2020 - 20
Hydrocarbon Processing - December 2020 - 21
Hydrocarbon Processing - December 2020 - 22
Hydrocarbon Processing - December 2020 - 23
Hydrocarbon Processing - December 2020 - 24
Hydrocarbon Processing - December 2020 - 25
Hydrocarbon Processing - December 2020 - 26
Hydrocarbon Processing - December 2020 - 27
Hydrocarbon Processing - December 2020 - 28
Hydrocarbon Processing - December 2020 - 29
Hydrocarbon Processing - December 2020 - 30
Hydrocarbon Processing - December 2020 - 31
Hydrocarbon Processing - December 2020 - 32
Hydrocarbon Processing - December 2020 - 33
Hydrocarbon Processing - December 2020 - 34
Hydrocarbon Processing - December 2020 - 35
Hydrocarbon Processing - December 2020 - 36
Hydrocarbon Processing - December 2020 - 37
Hydrocarbon Processing - December 2020 - 38
Hydrocarbon Processing - December 2020 - 39
Hydrocarbon Processing - December 2020 - 40
Hydrocarbon Processing - December 2020 - 41
Hydrocarbon Processing - December 2020 - 42
Hydrocarbon Processing - December 2020 - 43
Hydrocarbon Processing - December 2020 - 44
Hydrocarbon Processing - December 2020 - 45
Hydrocarbon Processing - December 2020 - 46
Hydrocarbon Processing - December 2020 - 47
Hydrocarbon Processing - December 2020 - 48
Hydrocarbon Processing - December 2020 - 49
Hydrocarbon Processing - December 2020 - 50
Hydrocarbon Processing - December 2020 - 51
Hydrocarbon Processing - December 2020 - 52
Hydrocarbon Processing - December 2020 - 53
Hydrocarbon Processing - December 2020 - 54
Hydrocarbon Processing - December 2020 - 55
Hydrocarbon Processing - December 2020 - 56
Hydrocarbon Processing - December 2020 - 57
Hydrocarbon Processing - December 2020 - 58
Hydrocarbon Processing - December 2020 - 59
Hydrocarbon Processing - December 2020 - 60
Hydrocarbon Processing - December 2020 - 61
Hydrocarbon Processing - December 2020 - 62
Hydrocarbon Processing - December 2020 - 63
Hydrocarbon Processing - December 2020 - 64
Hydrocarbon Processing - December 2020 - 65
Hydrocarbon Processing - December 2020 - 66
Hydrocarbon Processing - December 2020 - 67
Hydrocarbon Processing - December 2020 - 68
Hydrocarbon Processing - December 2020 - 69
Hydrocarbon Processing - December 2020 - 70
Hydrocarbon Processing - December 2020 - 71
Hydrocarbon Processing - December 2020 - 72
Hydrocarbon Processing - December 2020 - 73
Hydrocarbon Processing - December 2020 - 74
Hydrocarbon Processing - December 2020 - 75
Hydrocarbon Processing - December 2020 - 76
Hydrocarbon Processing - December 2020 - 77
Hydrocarbon Processing - December 2020 - 78
Hydrocarbon Processing - December 2020 - 79
Hydrocarbon Processing - December 2020 - 80
Hydrocarbon Processing - December 2020 - 80A
Hydrocarbon Processing - December 2020 - 80B
Hydrocarbon Processing - December 2020 - 81
Hydrocarbon Processing - December 2020 - 82
Hydrocarbon Processing - December 2020 - Cover3
Hydrocarbon Processing - December 2020 - Cover4
Hydrocarbon Processing - December 2020 - GP-1
Hydrocarbon Processing - December 2020 - GP-2
Hydrocarbon Processing - December 2020 - GP-3
Hydrocarbon Processing - December 2020 - GP-4
Hydrocarbon Processing - December 2020 - GP-5
Hydrocarbon Processing - December 2020 - GP-6
Hydrocarbon Processing - December 2020 - GP-7
Hydrocarbon Processing - December 2020 - GP-8
Hydrocarbon Processing - December 2020 - GP-9
Hydrocarbon Processing - December 2020 - GP-10
Hydrocarbon Processing - December 2020 - GP-11
Hydrocarbon Processing - December 2020 - GP-12
Hydrocarbon Processing - December 2020 - GP-13
Hydrocarbon Processing - December 2020 - GP-14
Hydrocarbon Processing - December 2020 - GP-15
Hydrocarbon Processing - December 2020 - GP-16
Hydrocarbon Processing - December 2020 - GP-17
Hydrocarbon Processing - December 2020 - GP-18
Hydrocarbon Processing - December 2020 - GP-19
Hydrocarbon Processing - December 2020 - GP-20
Hydrocarbon Processing - December 2020 - GP-21
Hydrocarbon Processing - December 2020 - GP-22
Hydrocarbon Processing - December 2020 - GP-23
Hydrocarbon Processing - December 2020 - GP-24
Hydrocarbon Processing - December 2020 - GP-25
Hydrocarbon Processing - December 2020 - GP-26
Hydrocarbon Processing - December 2020 - GP-27
Hydrocarbon Processing - December 2020 - GP-28
Hydrocarbon Processing - December 2020 - GP-29
Hydrocarbon Processing - December 2020 - GP-30
Hydrocarbon Processing - December 2020 - GP-31
Hydrocarbon Processing - December 2020 - GP-32
Hydrocarbon Processing - December 2020 - GP-33
Hydrocarbon Processing - December 2020 - GP-34
Hydrocarbon Processing - December 2020 - GP-35
Hydrocarbon Processing - December 2020 - GP-36
Hydrocarbon Processing - December 2020 - GP-37
Hydrocarbon Processing - December 2020 - GP-38
Hydrocarbon Processing - December 2020 - GP-39
Hydrocarbon Processing - December 2020 - GP-40
Hydrocarbon Processing - December 2020 - GP-41
Hydrocarbon Processing - December 2020 - GP-42
Hydrocarbon Processing - December 2020 - GP-43
Hydrocarbon Processing - December 2020 - GP-44
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