The acid gas scrubber tower was experiencing unstable top temperatures that posed risks. Conventional troubleshooting found issues with instrumentation and reflux flows but not the root cause. Thermal imaging identified a cold spot and uneven temperatures, revealing damaged packing and a blocked bed limiter inside the tower. Internal inspections confirmed the issues, and repairs with a new bed limiter stabilized the tower temperatures. Thermal imaging proved useful for identifying internal flow deviations without disrupting operations.
If it can go wrong – it will
If something looks odd – it is
Apparent safe systems can fail
Issues include
Metal dusting
Methanol or hydrogen fires
Intent changes
Methanation
“Safe Systems”
If it can go wrong – it will
If something looks odd – it is
Apparent safe systems can fail
Issues include
Metal dusting
Methanol or hydrogen fires
Intent changes
Methanation
“Safe Systems”
Pre-reforming
Flow-schemes
Feed-stocks
Catalyst handling, loading & start-up
Benefits of a pre-reformer
Case studies
Effects upon primary reformer
Data analysis
Reactor temperature profiles
Catalyst management
Summary
Capacity Enhancement of Ammonia Production By The Revamping of Ammonia.
In this project, we find conversion and temperature profile of a two catalyst bed with one interbed heat exchanger ammonia converter and a three catalyst bed with two interbed heat exchanger ammonia converter both have radial flow by using a pseudo homogeneous two dimensional mathematical model on the basis of principle of conservation of mass and energy balance with the help of MATLAB pde solver.We conclude that a three catalyst bed ammonia converter give a higher conversion and lower pressure drop compare to the two catalyst bed ammonia converter for the same volume of catalyst bed and same amount of feed stock.
This presentation covers frequent and costly incidents related to catalysts mal-operation with the focus of providing the plant operator with recommendations to avoid plant outages and catalyst losses.
Reformer Tube design principles
- Larsen Miller Plot
- Larsen Miller & Tube Design
- Design Margins - Stress Data Used
- Max Allowable & Design Temperature
- Tube Life
- Effect of Temperature on Life
- Material Types
HK40: 25 Cr / 20 Ni
HP Modified: 25 Cr / 35 Ni + Nb
Microalloy: 25 Cr / 35 Ni + Nb + Ti
- Alloy Developments
- Comparison of Alloys
Manufacturing Technology
- Welds
Failure mechanisms
- Failure Mechanisms - Creep
- Creep Propagation
- Common Failure Modes
- Uncommon Failure Modes
- Failure by Creep
- Creep Rupture - Cross Section
- Failure at Weld
Actions to Take if Tube Fails
- Pigtail Nipping
Inspection techniques
Classification of Problems
- Visual Examination
- Girth Measurement
- Ultrasonic Attenuation
- Radiography
Eddy Current Measurement
LOTIS Tube Inspection
LOTIS Compared to External Inspection
Steam Reformer Surveys - Techniques for Optimization of Primary Reformer Oper...Gerard B. Hawkins
Introduction
Background Radiation and Temperature Measurement
Reformer Survey Inputs
Other Troubleshooting Tools
Safety
Preparation
Onsite Data Collection
TWT Survey
Observation/Troubleshooting
Modelling and Analysis
Results/Outputs
Case Studies
Conclusions
Case Study 1
Case Study 2
Case Study 3
Conclusions
The value of selecting the right catalyst
Selecting the key performance criteria
Sources of data:
Plant data
Laboratory reactor data
Catalyst characterization
Recommendations
Pre-reforming
Flow-schemes
Feed-stocks
Catalyst handling, loading & start-up
Benefits of a pre-reformer
Case studies
Effects upon primary reformer
Data analysis
Reactor temperature profiles
Catalyst management
Summary
Capacity Enhancement of Ammonia Production By The Revamping of Ammonia.
In this project, we find conversion and temperature profile of a two catalyst bed with one interbed heat exchanger ammonia converter and a three catalyst bed with two interbed heat exchanger ammonia converter both have radial flow by using a pseudo homogeneous two dimensional mathematical model on the basis of principle of conservation of mass and energy balance with the help of MATLAB pde solver.We conclude that a three catalyst bed ammonia converter give a higher conversion and lower pressure drop compare to the two catalyst bed ammonia converter for the same volume of catalyst bed and same amount of feed stock.
This presentation covers frequent and costly incidents related to catalysts mal-operation with the focus of providing the plant operator with recommendations to avoid plant outages and catalyst losses.
Reformer Tube design principles
- Larsen Miller Plot
- Larsen Miller & Tube Design
- Design Margins - Stress Data Used
- Max Allowable & Design Temperature
- Tube Life
- Effect of Temperature on Life
- Material Types
HK40: 25 Cr / 20 Ni
HP Modified: 25 Cr / 35 Ni + Nb
Microalloy: 25 Cr / 35 Ni + Nb + Ti
- Alloy Developments
- Comparison of Alloys
Manufacturing Technology
- Welds
Failure mechanisms
- Failure Mechanisms - Creep
- Creep Propagation
- Common Failure Modes
- Uncommon Failure Modes
- Failure by Creep
- Creep Rupture - Cross Section
- Failure at Weld
Actions to Take if Tube Fails
- Pigtail Nipping
Inspection techniques
Classification of Problems
- Visual Examination
- Girth Measurement
- Ultrasonic Attenuation
- Radiography
Eddy Current Measurement
LOTIS Tube Inspection
LOTIS Compared to External Inspection
Steam Reformer Surveys - Techniques for Optimization of Primary Reformer Oper...Gerard B. Hawkins
Introduction
Background Radiation and Temperature Measurement
Reformer Survey Inputs
Other Troubleshooting Tools
Safety
Preparation
Onsite Data Collection
TWT Survey
Observation/Troubleshooting
Modelling and Analysis
Results/Outputs
Case Studies
Conclusions
Case Study 1
Case Study 2
Case Study 3
Conclusions
The value of selecting the right catalyst
Selecting the key performance criteria
Sources of data:
Plant data
Laboratory reactor data
Catalyst characterization
Recommendations
Forced cooling of a supercritical steam turbine after shut down of power plantSrikar Yadav
Forced cooling of a supercritical steam turbine after a shut down of power plant- types of cooling system, detailed analysis of cooling system under practical experience of experts in specified field.
production engineering 2 topic.
which includes the production logging tools, its application, categories of application and also some uses of the log with example in the practical life and physics.
Thermal plant instrumentation and controlShilpa Shukla
Detail working description of each components used in A Thermal or Coal based Plant for generation of electricity. Controlling and automation is described.
CFD comes handy in the investigations of heat transfer problems related to everyday usage . Placement of air-conditioned in large spaces is one such area where the use of computational fluid dynamics is envisaged in this case study .
AIChE Spring Conference 2015_Distillation Troubleshooting_Presentation
1. Quick and Easy Troubleshooting of a
Packed Tower:
Thermal Imaging as a Novel Method
Hendri Barnard and Elzette du Toit
Sasol Ltd, Secunda Synfuels Operations
2. Problem Definition
An Acid Gas Scrubber had an unstable top temperature.
The top temperature of the distillate was swinging 10 °C higher and 10 °C lower
than the set point and this posed a risk contamination of the overheads product to
the downstream units.
The reflux line entering the top of the tower was frozen on the outside of the line
which also raised suspicion.
ACID GAS SCRUBBER CASE STUDY
3. Process Description
The purposes of the acid gas scrubber are to:
• remove the steam and CO2 from NH3,
• concentrate the NH3.
An ammonium carbonation reaction is used to ensure that
all the CO2 is removed from the NH3 before sending the NH3
for further purification. The NH3 would be in excess and this
causes the CO2 to react until extinction. The excess NH3 is
removed at the top of the tower.
Two sections of packing are used to enlarge the contact area
For the ammonium carbonate ((NH4)2CO3) formation. The
reaction is exothermic and excess heat is removed in the
middle and top pump around systems.
The feed enters the tower below the first tray. The steam
present in the feed needs to be condensed which is done by a
bottom pump around system.
4. Process Description
Temperature is controlled to favour the (NH4)2CO3 formation
reaction.
A stream from the Trap Out Tray 2 in the middle section is
pumped through the middle pump around cooler to attain
the required temperature after which it is then reintroduced
above Packing Section 1.
Vapour leaving the middle pump around passes through a
chimney into Packing Section 2.
The top pump around system also aids in the formation of
(NH4)2CO3.
A stream from Trap Out Tray 3 is drawn off and pumped
through the top pump around cooler and reintroduced above
the second section of random packing.
A stream with a high purity of NH3 is used as a reflux and is
introduced right at the top of the tower.
This stream also controls the temperature at the top of the
tower and washes down any traces of (NH4)2CO3 present.
5. Conventional Troubleshooting
The first steps that were done to try and alleviate the problem were:
Check Instrumentation - The temperature transmitter used for the control of the
top temperature was found to be operating outside its specified range. This was
corrected but this didn’t lead to an improvement in the temperature control,
Top temperature control loop was investigated - The control loop was found to be
functioning as intended.
All pump around temperatures and tower pressures were within normal
operating limits,
The temperature above packing section 2 was seen to be much higher than on
the other phases; possibly indicating that the problem might be in the middle
section of the tower,
6. Conventional Troubleshooting
The top reflux was investigated - It was found to be different when compared
to the other phases. This was also detected by visual inspection as this was the
only reflux line that indicated ice formation on the outside of the line.
The reflux was adjusted to allow for similar compositions of the reflux when
compared to the other phases. This resolved the ice formation on the line
and did influence the temperature, however the temperature above packing
section 2 remained higher than normal,
Finally we decided to take thermal scans of the tower to help determining
the possible root cause for the instabilities seen.
7. Tower 1 (showing the instabilities)
Unedited picture displayed on the camera taken from adjacent column.
Thermal Imaging
8. Tower 1 (showing the instabilities)
Unedited picture displayed on the camera taken from adjacent column.
Thermal Imaging
9. Tower 1 (showing the instabilities)
Unedited picture displayed on the camera.
Thermal Imaging
10. Tower 2 (stable operation)
Unedited picture displayed on the camera taken from adjacent column.
Thermal Imaging
11. Tower 2 (stable operation)
Unedited picture displayed on the camera taken from adjacent column.
Thermal Imaging
12. Tower 2 (stable operation)
Unedited picture displayed on the camera taken ground angle.
Thermal Imaging
13. Top Section
Tower internals schematic drawing.
Thermal Imaging Comparison
Trays
Distillate Outlet
Top Pump
Around ReturnLiquid
Distributor
Man Hole
Vent
Reflux
Distributor
15. Top Pump Around Section
Tower internals schematic drawing.
Thermal Imaging Comparison
Top Pump
Around ReturnLiquid
Distributor
Packing Section 2
Man Hole
Man Hole
17. Top Section and
Top Pump Around Section
Tower internals
schematic drawing.
Thermal Imaging Comparison
Trays
Distillate Outlet
Top Pump
Around
Return
Liquid
Distributor
Man
Hole
Vent
Reflux Distributor
Packing Section 2
Packing Section 1
Man
Hole
Chimney Stand
Pipe
Top Pump
Around Outlet
Trap Out
Tray 3
23. Conclusion
• Thermal imaging proves to be another viable option
in packed tower troubleshooting.
• Able to visually inspect the flow pattern inside a
packed tower while it is in operation.
• Pro active planning and procurement of spares to
ensure that downtime is minimized.
24. Conclusion
• Very little expertise is required for capturing the
images.
• Deviations can easily be identified.
25. Drawback
• Lagging/insulation would need to be removed before
the thermal image can be taken.
• External fouling also acts as insulation and need to
be cleaned.