Paper 1a: Major Ammonia Leak Incident in Urea Plant.
Presenter: S. G. Gedigeri and K. M. Babu - OMIFCO, Oman
===============================================================
By : Muhammad Afzaal - Fauji Fertiliser Company
Limited, Pakistan
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Q 1a.1 : Did you have any Preventive Maintenance
/ Inspection plan before hand? I think the weld joint’s health should have
already been identified before failure.
A 1a.1 : OMIFCO plants are relatively new and
are in commercial operation since last six years only. OMIFCO is carrying out
risk based inspection for static vessels and rotary equipment in major shutdowns.
For high pressure piping handling toxic or flammable fluids only random
inspection is done based on industry experience. Before the incident we have
not checked this particular weld joint. It is not an industry practice and is
impossible to inspect all the welds in a mega complex like OMIFCO.
===============================================================
By : David Firth – Quest Integrity NZL Limited, New Zealand
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Q 1a.2 : Comments made were that the fatigue
performance was probably reduced as a result of incorrect PWHT (as the hardness
was excessive), the original installation (as there was a significant offset
after the failure), thermal expansion and vibration. What extent of vibration
monitoring & vibration modeling was carried out?
A 1a.2 : In
our regular vibration monitoring program only rotating equipment have been
covered so far. If any rotating equipment is found with very high vibrations or
the associated suction/discharge piping are
visually found to vibrate, then along with the equipment its associated
piping are also analyzed for vibrations.
===============================================================
By : G. K. Gautam – IFFCO - Aonla Unit, India
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Q 1a.3 : Has the welding record been checked for
subject weld whether proper PWHT has been carried out properly & welding consumables
of right quality have been used. What is
the impact of clamp on stress on pipe weld.
A 1a.3 : OMIFCO
plants were set up under the EPCC contract awarded on international competitive
bidding procedure. OMIFCO’S takeover of the plants took place after the
completion of the initial warranty period. The welding records could not be
traced as the contractor gave some jobs on sub contracts also. But OMIFCO
believes that the contractor has adhered to the approved WPS as prescribed by
the process licensor.
===============================================================
By : Carl Jaske – Det Norske Veritas, USA
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Q 1a.4 : When the initial leak was found and
clamped, did you perform an engineering assessment
of fitness for service and remaining life. It seems that this would have found
the problem before the break occurred?
A 1a.4 : The pipe thickness nearer to the leaky
joint was checked and found to be as per the specification. The weld joint
could not be inspected due to the persisting Ammonia leak and the urgency of
arresting the leakage to control the environment contamination.
===============================================================
By : Danny Franceus – Yara, Belgium
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Q 1a.5 : What are your recommendations for Adaptation
of Inspection Program towards other plants?
A 1a.5 : Good healthy condition of the paint or
insulation of the piping should be ensured by regular monitoring. If any damage
of the Insulation or paint condition noticed it should be attended immediately
after inspecting/assessing the condition of the exposed pipes. To take care of
damage occurring from inside of the pipe the thickness of all critical piping
should be examined by pre-decided schedule and planning at strategic locations
by providing corrosion monitoring windows/coupons.
===============================================================
By : Saleh Said Al Habsi – OMIFCO, Oman
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Q 1a.6 : What is the best method to attend
Ammonia Leak from Ammonia Pipeline?
A 1a.6 : We understand this depends on the
specific situation depending on the quantum of leakage, operated pressure of
the failed leaky portion and the contained quantity of Ammonia handled by that
piece of equipment. Where ever high pressures and higher volumes are involved
it might be prudent to isolate or stop the facility and repair it.
===============================================================
Paper 1b: Major An Alternative Approach for Leak Before Break Assessment to Postpone the First Internal Inspection of a Refrigerated Ammonia Storage Tank.
Presenter: Alex Scheerder - Stamicarbon bv, The Nethrlands
Pascal Schreurs – Sintra Engineers bv, The Netherlands
===============================================================
By : Mike Antony – ProPlant Inc., USA
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Q 1b.1 : The approach does not include bottom
plate circumferential weld with floor plate.
Recent inspection of a 10,000 MT tank had failures all around (360 Deg) this
weld. Number of other inspections has revealed the same.
A 1b.1 : This is correct; in the present EFMA
guideline the bottom circumferential weld with floor plate is not included. We
question this approach and we propose the EFMA to include the critical weld in
the guideline. We already did some fracture
mechanical analysis in a similar ammonia tank and concluded that indeed this
weld is critical.
===============================================================
By : Muhammad Abdullah – Fauji Fertilizer Company
Limited, Pakistan
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Q 1b.2 : What kinds of NDTs are employed for
checking the health of the Ammonia Tank at your plant.
A 1b.2 : In
the tank under investigation following NDE has been performed:
Visual inspection of the
outer tank wall; check for failures in painting system
UT
examination of outer tank wall, at random
Visual
inspection of tank foundation, settlement measurements
Infrared
thermography of tank wall for leakages
Paper 1d: Operator Training Simulator in Ammonia Plants:
Increase safety, Decrease Cost, and Strengthen Competitiveness
Authors : Klaus Schübel - SKW Stickstoffwerke Piesteritz GmbH, Germany
Norbert Ringer, Kisnaduth Kesore - Süd-Chemie AG, Germany
Marco Lanteri, Massimiliano Morniroli - APC Tech, Italy
Gregor Fernholz - Invensys Operations Management, Germany
Presenter: Klaus Schübel - SKW Stickstoffwerke Piesteritz GmbH, Germany Norbert Ringer, Kisnaduth Kesore - Süd-Chemie AG, Germany
Gerry Mak - Invensys Operations Management, U.K.
===============================================================
By : Shafi Ahmed – Karnaphuli Fertilizer Company Limited
(KAFCO), Bangladesh
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Q 1d.1 : 1. Time period for OTS implementation, 2. Cost of OTS implementation, 3. Manpower from
owner side.
A 1d.1 : The time and cost for OTS
implementation is highly dependent on the scope of the project. Invensys would
be happy to discuss your individual requirements.
The SKW project started in March 2008 and the
acceptance test was finished in July 2010. During the entire period an average
three SKW specialists were involved (project manager, chemical engineers,
experienced plant operator).
In the first year of operation you will need
2-3 employees to operate the OTS (trainer, hardware maintenance, chemical
engineer)
===============================================================
By : Dorothy Shafer – Baker Risk
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Q 1d.2 : Since the objective of the simulator
was to improve operator response during trips and emergency conditions, did you
include alarm management reviews as part of the project to reduce distraction
from unnecessary or unimportant alarms?
A 1d.2 : We
know very well, that a successful alarm management is very import for safe and
economic operation of an ammonia plant. The OTS was part of a project, which
included a copy of the actual version of Foxboro I/A system for both ammonia
plants, and we are going through the first steps of improving the alarm
management.
===============================================================
By : Malika Nait Oukhedou – Protomation, bv
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Q 1d.3 : a) How much money have you (SKW) saved
since the usage of the OTS upto now?
b) How
and where are the Trainees results being saved
c) How is
the communication done between Sud-Chemie’s Reaction Kinetics & Thermodynamics
and the dynamic model?
d) The
one million USD that was mentioned, does that include DCS hardware &
software in case the concept is a direct – connect solution?
A 1d.3 : a)
It is difficult to answer this question. The economic effect goes in different
directions: To avoid critical situations, to operate critical situations
better, to operate the plants closer to the optimum, to reduce the time for
education of new operators. It is impossible to decide accurate how much of the
success of the production is caused by the use of an OTS.
b) The Trainees results are documented in
separate files, which contain all necessary information.
c) The OTS replicates the equations from
Sud-Chemie directly in the simulation; there is no requirement for
communications with an external Kinetic/Thermodynamic model. A lot of cases
were run and regression equations were created.
Sud-Chemie has validated the performance of the representation
implemented.
d) The price for an OTS depends as remarked
earlier, on a lot of things. In our case it included not only the software and
hardware, but also costs for buildings and maintenance support and software
upgrading costs for the next years.
===============================================================
By : Dr. Hans H. Wagner – Ineos Enterprises, Germany
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Q 1d.4: How many OTS are in operation in the
world? Will this be becoming an industry
standard?
A 1d.4: Invensys
has delivered hundreds of operator training simulators around the world, in
many different process areas including refineries, petrochemical, oil and gas,
pharmaceutical, chemical and power generation. It is rapidly becoming an
industry standard, especially in the case of new plants and control system
updates. In Europe there are three OTS for ammonia plants in use, as far as we
know.
===============================================================
Paper S2: ID fan Low Flow problem and Repeated shaft failures of Semi-Lean Pump
Authors : Iftikhar Hussain Turi and Tamvada Srinivas - Qatar Fertiliser Co
Presenter: Iftikhar Hussain Turi and Tamvada Srinivas - Qatar Fertiliser Co
===============================================================
By : Muhammad Abdullah – Fauji Fertilizer Company,
Bangladesh
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Q S2.1 : When low flow problem was being observed
? Did you check the vibration level at fan casing.
A S2.1 : There
was slight increase in overall vibration
during low flow . But with vibration analysis the problem with cone
setting cannot be pin pointed. Flow related vibration can be due to many
reasons.
The method we used measured the actual flow
accurately & we could see the difference with Ammonia 2 fan clearly.
To
stop the plant for 5 days
to correct the cone settings required
a method to be 100 % accurate as justification.
===============================================================
By : Harrie Duisters – OCI Nitrogen
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Q S2.2 : Can you better explain, how the extra
vent works ?
A S2.2 : It
is only for priming the pump at start up to vent the air trapped below suction valve.
Q S2.3 : Is it only for start-up? No valves in vent line (see figure 2 ) ??
A S2.3:
The vent is only for initial priming, at start up . It has a valve at
the platform level for the suction valve. It can be seen in photo 7 in the
paper.
===============================================================
Paper 2c: Rupture of the primary reformer-mixed feed coil header at Tringen1
Authors : Stenn Mowassie and Laurent Ruhlmann -YaraTrinidad
Michael Schlaug - Yara International SA, Norway
Presenter: Stenn Mowassie -YaraTrinidad
===============================================================
By : Dorothy F. Maxwell Shaffer – Baker Risk
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Q 2c.1 : Was the reforming catalyst unaffected?
A 2c.1 : Yes, the reforming catalyst was
essentially unaffected. Post outage performance assessments on the reforming
catalyst did not show any evidence of reduction in activity or increase in
pressure drop.
Q 2c.2 : Did you have a previous history of PSV
failures on pre pop testing – and is there a policy to investigate those?
A 2c.2 : No we have not had specific historical
problems of PSV failures on pre-pop testing. Our policy now includes a shop
test and re-certification of all relief valves known to have lifted in service.
This applies even if the relief valve in question appears to have reseated.
===============================================================
By : Abdul Rahman Al Hats – OCI Nitrogen
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Q2c.3 : Did the modification of the MOV inlet
of HTS communicated and agreed by the Licensor of the Plant ?
A2c.3 : The
modification of the inlet MOV to the HTS followed the internal Management of
Change process and did not directly
involve the Licensor (Fluor) of the plant.
Q2c.4 : What will be the modification to prevent
the repetition of the same problem?
A2c.4 : The main modifications to prevent
repetition are as follows:
1) Since the HTS inlet MOV can act as a
sectioning valve for the plant, it is proposed to have pressure controlling
vent valves installed between all main process sectioning valves. Therefore the
installation of a pressure control vent valve from upstream of the HTS inlet
MOV to the vent header will be implemented.
2) Reinstallation of position alarms on HTS
inlet MOV and verification of the
functionality of all other major process MOV’s position alarms.
3) Upgrade the pressure relief valve sizing on
the HTS inlet. Each valve will be sized for 100% relief capacity therefore
resulting in a 2 x 100% relief arrangement.
4) Change in policy – Relief valves are to be
shop tested once the valve has lifted to verify that the valve integrity and
functionality has not been compromised
===============================================================
By : John Mason – Agrium Inc., Canada
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Q2c.5 : In addition to reviewing need for
additional redundancy in the pressure relief valves, are you reviewing or
considering any changes to the relief valves (metallurgy, style) ?
A2c.5 : Yes.
This will be taken into account as part of the Management of Change process.
The intention is to solve the root cause for both the sizing issue as well as
the mechanism causing damage on lifting.
===============================================================
By : Harrie Duisters – OCI Nitrogen
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Q 2c.6 : Can we get a copy of the power point
presentation for operator training?
A 2c.6 : Please
contact treveno.mowassie@yara.com to discuss the specifics of any requests.
Paper 2e: Failures of Pigtails: Why They Happen and How to Avoid Them
Authors : C. W. Thomas and M. J. Smillie - Quest Integrity Group
Presenter: M. J. Smillie - Quest Integrity Group
===============================================================
By : Reinaldo Caldera V. – Petroquimica de Venezuela
(Pequiven), Venezuela
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Q 2e.1: Did you replace the Pigtails?
A 2e.1: The plants whose pigtails were
removed for destructive sectioning did replace those pigtails. Pigtails in general are often removed (and
replaced) on criteria based on condition or inspection metrics e.g. measured
expansion of the tubes and on history. Numerous failures at the pigtail
terminal welds for example may lead to a decision to replace all pigtails
Q 2e.2: What material for pigtail are you
going to use for the next purchase order?
A 2e.2 :
Our clients have not gone away from Alloy 800H/HT (or equivalent
alloys). Careful specification of the
alloy composition, grain size and pigtail manufacturing processes allows
greater confidence of the performance in service.
===============================================================
By : Kang Xu – Praxair
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Q 2e.3: Recommendation on the optimal grain
size range for 800 HT?
A 2e.3: The actual grain size specification
will depend on design (e.g. number of bends), temperature in service,
inspection requirements and expected performance. Certainly, to avoid low ductility cracking,
grain sizes no coarser than ASTM Number 1 or 2 may be desirable. The optimal range is as little variation in
grain size as possible given the limitations of manufacturing (e.g. grain size
control during bending and annealing operations). That will vary from vendor to vendor.
Q 2e.4: Comment on API 530 LMP which treats
800, 800 H, and 800 HT the same?
A 2e.4 :
I think that API will distinguish between the base Alloy 800 and the
800H and 800HT variants. Data for Alloy 800 is not included in API 530 or API
579 and Alloy 800 would normally be considered a low temperature alloy for
corrosion resistance. I understand API considered Alloy 800H and HT to have the
same material performance under the design criteria of API 530, as a way to
accommodate the apparent variability of the creep performance of Alloy 800HT
under certain operating conditions. The
API 530 Material Data Book does provide separate LMP curves for Alloy 800H and
Alloy 800HT.
==================================================================
Paper 3a: Successful Operating Experience of CFCL Ammonia Plant Revamped with KBR KRESTM Technology
Authors : Upendra Singh - Chambal Fertilizers and Chemicals Ltd, India
Shashi Singh and Avinash Malhotra - KBR, USA
Presenter: Upendra Singh - Chambal Fertilizers and Chemicals Ltd, India
Shashi Singh - KBR, USA
===============================================================
By : C. M. T. Britto – Rashtriya Chemicals and
Fertilizers Ltd., India
--------------------------------------------------------------------------------------------------------------
Q 3a.1: During the presentation you said that
there was a hot spot in KRES which was fixed. Can you please elaborate on this
problem and how it was fixed?
A 3a.1: The hot spot at the top was caused due
to an internal dent on a metal part happened during equipment’s road
transportation. This was leading to higher than usual metal temperature. Unit
was kept operational without any impact on ammonia production rate, external
steam sparger was used. This problem was completely solved by repairing the
affected part in the annual shutdown of April 2010
Q 3a.2: What are the major equipment changes
that will be incorporated while revamping from GV to aMDEA system during 2nd
stage revamp? Does it involve significant Capital investment?
A 3a.2 : This requires new absorber, LP Flash
vessel and some semilean pumps. Capital cost as well as execution during
shutdown is significant. We knew these aspects from the conceptualization
stage, but significant benefits of the 2stage MDEA process had convinced us to
follow this feature. Also we know other ammonia plants have implemented such a
revamp and have benefitted in long run.
===============================================================
By : K. M. Babu – Oman India Fertilizer Company, Oman
--------------------------------------------------------------------------------------------------------------
Q 3a.3: What is the pressure drop profile
between Primary Reformer inlet and RG Boiler inlet before and after KRES
installation?
A 3a.3: Pressure drop values between these two
points at base case and post revamp are 3.5 and 2.0 kg/cm2 respectively. Plant
load post revamp is 1781 (vs. base 1608) MTPD as described in the paper.
Pressure drop does not increase with production throughput since the reforming
exchanger is added in parallel.
Q 3a.4: What is the temperature profile of Secondary
Reformer before and after KRES installation?
A 3a.4 : Temperature of the gases at the very
top during and after combustion is slightly higher as flow rate of process air
relative to the reformed gas is relatively increased. Final outlet temperature
is slightly more or similar to before per overall operations. The new
conditions are easily handled in the secondary reformer as is proven over two
years of operation in CFCL and off-course earlier in the previous two KRES
units that followed the scheme without primary reformer as explained in the
paper.
===============================================================
By : Venkat Pattabathula – Incitec Pivot Ltd., Australia
--------------------------------------------------------------------------------------------------------------
Q 3a.5: How was the dP across KRES – SOR and
current?
A 3a.5: The dP across KRES was about 1.0
kg/cm2 at SOR and about 2.0 kg/cm2 currently. Since reforming exchanger works
in parallel to primary and secondary reformers, pressure drop is not an issue.
The reforming exchanger is able to operate with dP of up to 4 kg/cm2.
Q 3a.6: What about Nox levels in Reformer
stack? Have they come down?
A 3a.6: Total Nox level inside the ammonia
plant is related to fuel firing in the furnace, hence it comes down in line
with the reduced firing in primary reformer. Overall whole complex Nox is
expected to be less with overall energy savings.
Q 3a.7: Add on converter design. Hot wall
or Quench Gas Cooling of shell?
A 3a.7: It is a Hot wall design, i.e.
converter pressure vessel has same temperature as the feed gas has.
===============================================================
Paper 3b: Woodward, Oklahoma Ammonia Converter Revamp:
More Efficiency and Reliability through Innovation
Authors : Debra Lawrence - CF Industries
Jamie Ballard - Süd-Chemie, Inc.
Francesco Baratto - Ammonia Casale S.A.
Presenter: Debra Lawrence - CF Industries
===============================================================
By : John Mason – Agrium
--------------------------------------------------------------------------------------------------------------
Q 3b.1: Have you quantified the benefit of the
converter internal replacement vs. replacing the catalyst? In other words, what percentage of benefit is
from the new internals and what percentage can be attributed to new catalyst?
A 3b.1: It is difficult to separate and
quantify the improvements based on the new internals vs. the new catalyst.
Another aspect is the fact that we had bypassing occurring in the packing gland
at the outlet as well as some bypassing in the internal heat exchanger prior to
changing out the internals. We believe
the bypassing in the packing gland at the cold-shot and outlet was occurring
when the S-200 basket was initially installed. We found that a “retaining ring”
was missing when we removed the old internals. So we cannot really fairly
compare Start-of-run conditions from the new catalyst and old catalyst. Another aspect of comparing the Start-of-run
conditions of the previous catalyst and the new catalyst is we were not making
methanol at the start-run with the previous catalyst and we were making
methanol at the start-of-run with the new catalyst and that has an effect on
the production rates. When we are making
methanol our inlet inerts to the converter is about 5% higher than when we are
not making methanol and of course that will have an effect on the converter
performance.
===============================================================
By : Harrie Duisters – OCI Nitrogen
--------------------------------------------------------------------------------------------------------------
Q 3b.2: What is the performance of the
Amomax-10 catalyst after 2 years of operation?
A 3b.2: At this time the performance is very
satisfactory. We believe we may even had
a CO/CO2 poisoning event (from the methanator) that may have affected the
performance, but it appears that the catalyst recovered from the poisoning.
Even now after 2.5 years on-stream, the catalyst activity is basically at the
expected level for this time onstream, and also above the expected magnetite
performance for this time onstream.
===============================================================
By : Upendra Singh – Chambal Fertilisers and Chemicals Limited,
India
--------------------------------------------------------------------------------------------------------------
Q 3b.3: What is the volume of catalyst in new
converter?
A 3b.3: 1362 ft3
Q 3b.4: What was the final reason for the
decision of choosing Amomax-10 catalyst?
Did you look for commercial references of the catalyst in any plant?
How long are these references?
A 3b.4: One of the reasons was that the
Amomax-10 has less water make during the reduction at initial startup. Another
reason, costs was a factor but not a major factor. Yes, we did talk to another
Amomax-10 customer. Of course the time
in service was not very old since Amomax-10 hasn’t been in use but just a few
years. But in talking to the reference we found that time in the startup heater
after shutdowns was greatly reduced as well.
At the time, there were references that were almost 5 years old, which
was long enough to be deemed commercially successful.
===============================================================
By : Glenn A. Combs – Chem-Engineering Services, USA
--------------------------------------------------------------------------------------------------------------
Q 3b.5: Could you please explain why the post
retrofit single pass conversion was only about 12.8%? Many plants with inter-cooling
have 14-16% single pass conversion?
A 3b.5: The Flour design plant uses an aqua
ammonia refrigeration system. Normally, a refrigeration compressor with a
closed loop refrigeration system is employed, therefore a refrigeration
compressor is not used, and instead has an aqua/ammonia refrigeration unit.
The main advantage is a cheaper ammonia
product, since there is a big cost saving in not having to generate the large
quantities of steam that would be necessary to drive a refrigeration
compressor. But as a result of the
unconventional aqua/ammonia refrigeration unit, the syngas entering the ammonia
converter contains about 4.0 mol% ammonia.
Moreover, the inert content in the loop is
relatively high from 12-17 mol%
===============================================================
By : Eddy Cooper – Agrium, Canada
--------------------------------------------------------------------------------------------------------------
Q 3b.6: How much of the significant efficiency
gains do you attribute to simply replacing the aging converter catalyst? Can
you break down your O.7 MMBtu/st gains among the various things you fixed and
improved?
A 3b.6: It is difficult to separate and
quantify the improvements based on the new internals vs. the new catalyst.
Another aspect is the fact that we had bypassing occurring in the packing gland
at the outlet as well as some bypassing in the internal heat exchanger prior to
changing out the internals. We believe
the bypassing in the packing gland at the cold-shot and outlet was occurring
when the S-200 basket was initially installed. We found that a “retaining ring”
was missing when we removed the old internals.
So we cannot really fairly compare Start-of-run conditions from the new
catalyst and old catalyst. Another aspect of comparing the Start-of-run
conditions of the previous catalyst and the new catalyst is we were not making
methanol at the start-run with the previous catalyst and we were making methanol
at the start-of-run with the new catalyst and that has an effect on the
production rates. When we are making methanol our inlet inerts to the converter
is about 5% higher than when we are not making methanol and of course that will
have an effect on the converter performance.
===============================================================
By : G. K. Gautam – IFFCO Aonla Unit, India
--------------------------------------------------------------------------------------------------------------
Q 3b.7: Whether all glands / packing in S-200
during casale modification of internals were replaced by elasto seals?
A 3b.7: Casale uses elastic seals for all the
inaccessible (internal parts) of the cartridge.
Packing is still used on cartridge top cover and outlet pipe.
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