-
The Successful Debottlenecking of the OCI Beaumont Complex
The OCI Beaumont facility is an integrated methanol and ammonia
complex that was built in the late 1960’s and revamped in the
1980’s with Lurgi’s parallel steam raising methanol converters. In
2012,
the OCI Beaumont facility was restarted after being moth-balled
in 2004. On restart, the plant ex-ceeded design rates and energy
consumption for the case without CO2 addition. In 2015, a
debottle-neck project was successfully implemented to increase
methanol and ammonia production by 25% and 12% respectively. This
paper discusses the safety measures taken during shutdown to
preserve
methanol synthesis catalyst while performing upgrade works in
the high-pressure synthesis loop; and the successful restart and
recovery from a start-up incident that posed great risk to
Clariant’s high performing MegaMax® methanol synthesis catalyst,
already close to 3 years on-stream. Also dis-
cussed are the upgrades made to the facility to increase
capacity while considering optimum operating conditions for
extended catalyst life.
Brandan Rossi OCI Beaumont, Beaumont, TX
Michelle Anderson Clariant, Louisville, KY
Introduction
he OCI Beaumont Complex produces both methanol and ammonia. The
front end of the unit converts natural gas to syn-
gas which is suitable for methanol production (similar to an
ammonia front end, except without CO Shift Converters and CO2
removal since CO and CO2 are required for methanol production).
There is a methanol synthesis loop and an ammo-nia synthesis loop
which utilizes recovered hy-drogen from the methanol plant along
with addi-tional required hydrogen and nitrogen over the fence. The
integrated facility was restarted in 2012 after being mothballed by
the previous owner in 2004. Following the restart, OCI stud-ied the
feasibility of debottlenecking the plant
with the target of increasing methanol and am-monia capacity by
25% and 12% respectively. The project also included environmental
up-grades and energy improvement initiatives. The study showed that
there were no limitations at the methanol converter which was
loaded with Clar-iant’s high activity MegaMax® 800 catalyst. As
part of planning for the debottleneck shut-down and restart,
careful attention was given to preserve the high activity Clariant
MegaMax® 800 methanol synthesis catalyst shown in Figure 1. Similar
to other copper based syngas catalysts such as low temperature
shift (LTS) catalyst, methanol synthesis catalyst will react
exothermi-cally with air potentially causing a high tempera-
T
792018 AMMONIA TECHNICAL MANUAL
-
ture excursion that can affect catalyst perfor-mance or worse
lead to catalyst and/or vessel fail-ure.
Figure 1. MegaMax® 800 6x4 mm Tablets
Cu/Zn Methanol Synthesis Catalyst On restart, all operations
performance targets were met or exceeded, and the debottlenecking
was deemed successful.
Project Feasibility From 2012 to 2015 prior to the
debottlenecking, the plant synthesis loop showed consistent, high
performance. Through technical collaboration with Clariant, the
MegaMax® 800 catalyst was operated at lower than design temperature
which significantly extended its life by reducing the ef-fects of
typical sintering that similarly affects LTS catalyst. The proven
success of Clariant’s installed high activity MegaMax® 800 methanol
synthesis cat-alyst was a paramount component in the feasibil-ity
of the debottlenecking project. Clariant pro-jected that the
installed catalyst activity and volume was sufficient to exceed the
targeted methanol production. This was a substantial sav-ings in
terms of capital expenditure required for debottlenecking. Based on
the high conversion
rates at low temperature, the projected remaining life of the
catalyst showed that replacement of the catalyst was not needed for
the debottlenecking project further improving its feasibility.
Figure 2 shows the performance of the MegaMax® 800 catalyst at low
operating temperature up to the debottlenecking project. The
converters oper-ated at 18oC (32oF) lower than design tempera-ture
yet achieved over 98% loop carbon conver-sion.
Figure 2. Total Carbon Conversion and Con-verter Operating
Temperature from 2012 to 2015 Operating the converters at low
temperature raised some concern of the possibility of wax
for-mation and deposition on the downstream cool-ing heat
exchangers. This had the potential to in-crease loop pressure drop,
reduce heat exchanger efficiency and thereby reduce overall plant
effi-ciency and yield. Such low operating tempera-tures are not
typical within the industry for that reason, but Clariant was
confident that the cata-lyst components were of a high quality to
safely operate in this region. Concerns of wax for-mation were
eased over time as there were no op-erating conditions that
suggested that it was oc-curring. In fact, after three years with
MegaMax® 800 catalyst in service, inspection of the loop cooling
heat exchanger tubes showed negligible wax build-up. Figure 3 shows
a pic-ture of the findings.
80 2018AMMONIA TECHNICAL MANUAL
-
Figure 3. Picture of OCI Loop Heat Exchanger after 3 years
in-service at low temperature con-verter operation
Debottlenecking Strategy To meet the Debottleneck Project
targets, the fol-lowing modifications were made:
• Installation of a pre-reformer and preheater to reduce the
load of the primary reformer
• Installation of a deep desulfurization vessel to protect the
pre-reformer catalyst from sul-phur poisoning
• Replacement of the reformer tubes with larger ID, thinner
walled tubes to limit the in-crease in pressure drop as well as
increase heat transfer efficiency
• Installation of a feed gas saturator to meet in-creased steam
demand while lowering plant waste water
• Upgrade of the methanol and ammonia syn-thesis loop
compressors
• Increase the cooling capacity in the methanol and ammonia
synthesis loops.
• Replaced specific trays in the Distillation unit In addition
to the capacity increase modifica-tions, the following
environmental improve-ments were made to meet the Texas Commission
on Environment Quality (TCEQ) permits for the project:
• Installation of a selective catalytic reduc-tion unit (SCR) in
the reformer flue gas stream to reduce NOx emissions
• Removal of flue gas liquid fuel burners in the reformer
convection section
• Reduction of plant wastewater by utiliza-tion in the feed gas
saturator.
• Installation of a new reformed gas flare system. All frontend
process vents were rerouted from atmosphere to the flare
header.
Schematics of the highlighted modifications is provided in
Figures 4a and 4b.
Figure 4a. Front End Debottleneck Schematic
SCR
CoolingDesulphur
ization
DeepDesulphur-
izationSaturator
Prereformer Heater
PrereformerSteam
Reformer
Waste Heat Recovery
ProcessCondensate
Distillation Fusel Oil
DistillationWater
812018 AMMONIA TECHNICAL MANUAL
-
Figure 4b. Back End Debottleneck Schematic With the additional
rates to the methanol synthe-sis loop, air coolers were installed
to increase the cooling capacity and achieve effective separation
of crude methanol from the converter effluent. These air coolers
are shown in Figure 5.
Figure 5. Air Coolers Installed in the Methanol
Synthesis Loop To achieve increased capacity at the front end,
the bottlenecks identified were the pressure drop limitation of the
front end based on existing com-pression capability, lack of steam
availability, and primary reformer furnace duty.
By installing the pre-reformer, the total increase in duty
required at the primary reformer was re-duced. The replacement of
the primary reformer tubes, already close to 10 years on-stream,
with a larger ID thinner wall design allowed increased heatflux to
the process gas and a lower pressure drop increase. The feed gas
saturator provided the additional steam requirements to achieve the
re-designed steam to carbon ratio. Additionally, it reduced CO2
emissions of the plant as the process con-densate from the front
end cooling section was re-routed from the CO2 stripper directly
into the process. Dehydrator Column tails water along with Fusel
Oil, which is a mixture of water and higher alcohols drawn off from
the distillation unit, was also re-routed to the feed gas saturator
which reduced the plant’s net wastewater flow to its bio-oxidation
pond. The addition of the selective catalytic reduction (SCR)
equipment was necessary to reduce the NOx emissions from the
primary reformer and new pre-reformer fired heater to meet the
neces-sary permit levels.
Shutdown Planning – Synthesis Catalyst The preservation of the
methanol and ammonia synthesis catalysts were of utmost importance
to ensure production and energy targets were met post shutdown as
well as ensuring that the re-maining life of the MegaMax® 800
catalyst would allow high productivity until the next planned
outage some 3-4 years later. As the am-monia converter loop
required no work that posed a risk to the installed catalyst,
nitrogen blanketing and isolation sufficiently protected it. By
contrast, the copper-based methanol synthesis catalyst required a
special procedure to isolate the catalyst as the work required in
the synthesis loop was done under atmospheric conditions.
Cooling Water Heat Exchanger
Separator
SynGas Comp-ression
Recirc-ulation
In/Out Heat Exchanger Converters
Air Coolers
82 2018AMMONIA TECHNICAL MANUAL
-
With guidance from Clariant, the threat to the MegaMax® 800
catalyst during and after the shutdown was carefully assessed,
namely:
• MegaMax® 800 reactivity. Exposing this catalyst to air would
lead to spontaneous self-heating with the potential for
uncontrolled high temperature excursion. High tempera-ture could
lead to catalyst fusing, complete deactivation and even vessel
damage.
• MegaMax® 800 performance. The copper based catalyst is
extremely sensitive to small levels of oxygen which will oxidize
the cata-lyst leading to localized heating that can sin-ter the
small copper crystallites which give it high activity.
Additionally, the physical in-tegrity of the catalyst can be
weakened by re-ducing the crush strength through an
oxida-tion/reduction process. Reduced crush strength could lead to
increased bed pressure drop during restart and over time.
• MegaMax® 800 impurity poisoning. Any work conducted in the
loop which exposes piping and equipment metallurgy to the
envi-ronment has the potential to form loose, scaly rust which on
restart can deposit at the top of the catalyst bed. Iron catalyzes
Fischer-Trop-sch reactions which promote the formation of
by-products such as higher hydrocarbons and wax. These by-products
can reduce the loop efficiency and plant yield by adding
addi-tional load on the distillation unit, fouling the cooling heat
exchangers and reducing the loop separator efficiency.
A typical modern methanol synthesis loop oper-ates at around 100
bar (1450 psi) with the large diameter process piping fully welded
without gasketed flanges to prevent leakage. However, the OCI
methanol synthesis loop, consisting of two Lurgi-designed steam
generating converters in parallel, is designed with two inlet and
two outlet 16 inch flanges for each converter (Figure 6). Thus
isolation of the converters required
eight, 16 inch ½-inch thick slip blinds. In collab-oration with
Clariant, the blinding and un-blind-ing procedure was written.
Figure 6. Parallel Steam Generating Methanol
Converters at OCI Beaumont
Blinding and Shutdown
To minimize the risk of air exposure to the meth-anol synthesis
catalyst, the following steps were established following normal
shutdown:
1. The steam side was emptied and pressurized with nitrogen.
2. The loop was depressured to 1-2 psi 3. The two converters
were isolated from each
other via hand valves in the loop.
4. Blinds were installed one at a time to avoid any chimney
effects that can suck air through the catalyst
5. All four blinds on the first converter were in-stalled and
the converter pressured to 1-2 psig with nitrogen before proceeding
to the sec-ond converter.
6. To ensure positive pressure was maintained in the converter,
a nitrogen hose was fitted to a 2” valve at the bottom of the
converter and a water seal assembly was connected at the 1” sample
connection at the converter inlet piping. The water seal assembly
consisted of ½” tubing submersed 2-3 inches deep into
832018 AMMONIA TECHNICAL MANUAL
-
water filled in a 50 gallon drum. Before in-stalling a blind,
positive nitrogen flow was established via the nitrogen hose and
vented at the water seal. The bubbling rate at the wa-ter seal was
monitored continuously by a ded-icated operator and nitrogen flow
was ad-justed as necessary when a flange was opened.
7. The loop piping and equipment were opened up only after all
blinds were successfully in-stalled and the converters were at 1-2
psi with nitrogen.
During the shutdown the nitrogen pressure at the DCS was
monitored as well as the limited tem-perature measurements around
the converter. Following the installation of the air cooler in the
synthesis loop and the inspection and cleaning of the water cooled
heat exchanger and the separa-tor, special care was taken to ensure
that the pip-ing and equipment were free from rust and loose iron
deposits.
Blind Removal
The process for pulling the blinds required spe-cial precaution
as the inlet piping and associated equipment was a separate system
than the outlet piping and associated equipment with the blinds
installed. These systems had to be treated sepa-rately and
precautions taken to avoid introducing air from these systems to
the converter. The fol-lowing steps were followed:
1. The inlet and outlet loop piping and equip-ment systems were
pressure purged with ni-trogen to 70 psi at least 4 times each
until ox-ygen levels were less than 0.5% by volume.
2. In order to ensure positive pressure in the converter, the
water seal was again installed and nitrogen flow was established
from the bottom of the converter and vented at the in-let using the
wet seal assembly.
3. One blind was pulled at a time to avoid chim-ney effects and
sucking air through the cata-lyst.
4. A dedicated operator was stationed at the wa-ter seal to
monitor the bubbling rate. Caution was taken when removing a blind
and the ni-trogen flow was increased as necessary.
5. The process was repeated on the other con-verter.
6. The loop was finally pressurized to 70 psig with nitrogen to
check for leaks.
Plant Restart Incident The start-up of the front end commenced
in April 2015 and required the commissioning of the var-ious new
equipment items. On April 21st, 2015, the methanol synthesis loop
was in start-up with the catalyst at temperature. While increasing
the pressure with make-up gas, the gasket inlet the west converter
blew out. Immediate action was taken to depressure and purge gas
from the loop. Clariant was contacted and all precautions were
again put in place to protect the active MegaMax® 800 catalyst
while the eight inlet and outlet converter piping gaskets were
replaced with new ones.
Performance Post Debottleneck On April 22nd methanol production
commenced and plant rates were increased over a period of time
while the plant conditions were optimized. During this period,
Clariant was consulted on the manner in which to optimize the loop
considering the need to increase the converter steam drum header
pressure sufficiently for process steam feed to the front end. It
was understood during the project design phase that this would be
nec-essary and would effectively increase the con-verter operating
temperature by 7oC (13oF) post shutdown. By May 23, 2015, the
target produc-tion of 2500 MTPD (2750 STPD) was achieved.
84 2018AMMONIA TECHNICAL MANUAL
-
Further optimization resulted in a maximum pro-duction of 2550
MTPD (2810 STPD) being achieved. Changes to some key performance
indicators of the plant performance following the debottleneck
project are shown in Table 1 below:
Parameter Post Debottleneck
Methanol Production In-crease
550 MTPD (606 STPD) 28 %
Ammonia Production In-crease
165 MTPD (182 STPD) 20 %
Energy Utilization Reduction Natural Gas Energy/Ton Methanol
2 %
Reduction of Import Hydrogen Flow/Ton NH3 22 %
Fluegas NOx reduction 90 %
Reduction in Wastewater ef-fluent flow to BioOxidation Pond
66 %
Table 1. Changes in Plant Key Performance In-dicators
Post-Debottleneck
Loop and MegaMax® 800 Performance
Despite the high risk that the active MegaMax® 800 was exposed
to air during the shutdown and during the restart incident, which
had the poten-tial to impact its activity as well as physical
in-tegrity, the activity of the catalyst remained un-changed even
at the higher space velocity through the catalyst (i.e. higher
process flow/vol-ume of catalyst). Further, the pressure drop
re-mained unchanged, and, in fact, at over 5 ½ years in service at
the time of writing, the pressure drop is still at the start of run
value. Some key operating parameters are given in Ta-ble 2:
Parameter Pre-Project Post-Project
Make-up Gas Stoichiometric Number
3.00 2.92
Recycle Ratio 4.9 3.7
Converter Oper-ating Tempera-ture
235oC (455oF)
242oC (468oF)
Table 2. Key Loop Operating Parameters For methanol synthesis,
the following chemical reactions occur:
CO + H2 ↔ CH3OH CO2 + H2 ↔ CH3OH + H2O
The stoichiometric number (SN) of the make-up gas is a measure
of the amount of carbon monox-ide and carbon dioxide relative to
hydrogen in the process gas and is given by the equation:
SN = (H2 – CO2) (CO + CO2)
A make-up gas composition with SN close to 2.05 is optimum for
methanol synthesis. By the debottlenecking modifications made in
the front end, the make-up gas SN was reduced with more CO and CO2
relative to hydrogen which technically improves loop performance
and efficiency as less purging is required. With this improvement,
the lower recycle ratio was compensated. Figure 7 shows the
performance of the loop from start of run to December 2017 and
identifies the unchanged loop efficiency and the increase in
op-erating temperature of the converters post-debot-tleneck. It
also clearly shows the stability of the MegaMax® 800 catalyst from
start of run to over 5 ½ years on-stream.
852018 AMMONIA TECHNICAL MANUAL
-
Figure 7. Loop performance from SOR to
December 2017
As Figure 7 shows, the operating temperature of the MegaMax® 800
catalyst was increased in a step change fashion following the
debottleneck project. Similar to LTS catalyst, optimization of the
methanol synthesis catalyst over time is achieved by strategically
increasing the operating temperature in increments to improve
conversion but being mindful that large increases can prem-aturely
reduce the life of the catalyst. The by-product make at OCI
continues to be low with the MegaMax® 800 high selectivity
cata-lyst. This has significant energy saving benefits in the
distillation section and thus improves the energy utilization of
the complex. Laboratory analysis of the crude methanol from the OCI
syn-thesis loop shows low levels of all by-products in comparison
to plant guarantee figures. Table 3 lists the key byproducts and
what percent of the guarantee figure is present for each.
By-product in Crude Methanol
Percent of Plant Guarantee Value
(5 Years On-stream)
Ethanol 53%
Total Higher Alcohols 34%
Di-methyl ether (DME) 62%
Methyl Formate 53%
Acetone Not Detected
Table 3. By-Product Make in Crude Methanol Based on the
stability of the catalyst performance post-debottlenecking, it is
clear that the well planned procedures and actions taken to protect
the catalyst during the shutdown and during the start-up incident
proved to be a success.
Plant Projection
OCI Beaumont continues to look at ways in which production can
be increased. Currently an expansion project is under review. The
timing of such project is dependent on the remaining life of the
methanol synthesis catalyst. Based on cur-rent catalyst performance
and the maximum lim-itation of the catalyst operating temperature
set by mechanical design, Clariant continues to guide OCI Beaumont
for planning purposes. As an example, Clariant provides routine
catalyst evaluations with guidelines on optimization for
temperature increases and remaining life projec-tions. An example
of such projection is shown in Figure 8 below.
86 2018AMMONIA TECHNICAL MANUAL
-
Figure 8. Converter Operating Temperature
Projection by Clariant The proven performance of Clariant’s
MegaMax® 800 catalyst has shown that through collaborative
partnership a catalyst change out cycle of 6+ years is possible.
This long life is a significant financial benefit to a producer
like OCI when catalyst cost, shutdown costs and lost production is
considered.
Conclusion In line with OCI’s strategy of growth into a global
producer of fertilizers and industrial chemicals, the acquisition,
restart, and debottle-neck of the OCI Beaumont complex has made the
facility into one of the world’s largest merchant methanol
producers. The debottleneck project of 2015 achieved a sig-nificant
increase in methanol and ammonia pro-duction capacity, and at the
same time, complied with all permitted emission levels. With the
successful implementation and results of the debottlenecking
project, OCI continues to look at opportunities for further
expansion.
Acknowledgments The authors wish to acknowledge OCI N.V. and OCI
Beaumont management on their vision and leadership in successfully
executing the debot-tleneck project. Additionally, we wish to
acknowledge the contributions of the technical specialists,
operations and maintenance teams whose commitment and dedication to
the com-plex is invaluable.
872018 AMMONIA TECHNICAL MANUAL
-
88 2018AMMONIA TECHNICAL MANUAL
IntroductionProject FeasibilityDebottlenecking Strategy
Shutdown Planning – Synthesis CatalystBlinding and ShutdownBlind
Removal
Plant Restart IncidentPerformance Post DebottleneckLoop and
MegaMax® 800 PerformancePlant Projection
ConclusionAcknowledgmentsBlank Page
/ColorImageDict > /JPEG2000ColorACSImageDict >
/JPEG2000ColorImageDict > /AntiAliasGrayImages false
/CropGrayImages true /GrayImageMinResolution 300
/GrayImageMinResolutionPolicy /OK /DownsampleGrayImages true
/GrayImageDownsampleType /Bicubic /GrayImageResolution 300
/GrayImageDepth -1 /GrayImageMinDownsampleDepth 2
/GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages true
/GrayImageFilter /DCTEncode /AutoFilterGrayImages true
/GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict >
/GrayImageDict > /JPEG2000GrayACSImageDict >
/JPEG2000GrayImageDict > /AntiAliasMonoImages false
/CropMonoImages true /MonoImageMinResolution 1200
/MonoImageMinResolutionPolicy /OK /DownsampleMonoImages true
/MonoImageDownsampleType /Bicubic /MonoImageResolution 1200
/MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000
/EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode
/MonoImageDict > /AllowPSXObjects false /CheckCompliance [ /None
] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false
/PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000
0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true
/PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ]
/PDFXOutputIntentProfile () /PDFXOutputConditionIdentifier ()
/PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped
/False
/CreateJDFFile false /Description > /Namespace [ (Adobe)
(Common) (1.0) ] /OtherNamespaces [ > /FormElements false
/GenerateStructure false /IncludeBookmarks false /IncludeHyperlinks
false /IncludeInteractive false /IncludeLayers false
/IncludeProfiles false /MultimediaHandling /UseObjectSettings
/Namespace [ (Adobe) (CreativeSuite) (2.0) ]
/PDFXOutputIntentProfileSelector /DocumentCMYK /PreserveEditing
true /UntaggedCMYKHandling /LeaveUntagged /UntaggedRGBHandling
/UseDocumentProfile /UseDocumentBleed false >> ]>>
setdistillerparams> setpagedevice
