Listen To The Pump Master, His Story Never Wears Down

Example of a worn impeller at the Damen Dredging Experience
Example of a worn impeller at the Damen Dredging Experience

This week is the triannual WODCON conference1. This edition will be held in lovely Copenhagen, in itself already a reason to be there. But there is more, the program is packed with interesting items. Starting with the opening ceremony with the Danish minister of transport and the Corporate Executives Discussion on sustainability. The Fehmarnbelt Tunnel Link will be a hot topic all through the program. My personal suggestion would be to attend Session 4: ‘Hydraulic Transport’ on Tuesday 17. Two of my highly regarded colleagues will be presenting their work on very interesting topics.

Damen colleagues present at the WODCON 2022, (l) Rick Bekkers, (r) Suman Sapkota
Damen colleagues present at the WODCON 2022, (l) Rick Bekkers, (r) Suman Sapkota

Rick Bekkers has been involved in the development of our new ProDredge edition. It is a slurry transport estimation tool. Where Ewout van Duursen has been working tirelessly on programming the tool, Rick has been checking the models and the results against known literature. He will show you the new reports generated and the insights they will give you for evaluating a proposed dredging system.

ProDredge presentation of a dredging system to be evaluated
ProDredge presentation of a dredging system to be evaluated

Suman Sapkota will be presenting his favourite topic: ‘Erosion estimation on the impeller blades of centrifugal dredge pumps’. He has been working on this topic ever since his own graduation project.2 Over the years he spend pondering over this issue and gradually grew in experience with the problem. Based on his ideas, he managed to start a cooperation with the Delft University of Technology and have a master student working on the practical details of his plans. Previously, I’ve written about the graduation of Wim Kleermaker in another article.3

Wim Kleermaker during the practical phase of his graduation in dredging
Wim Kleermaker during the practical phase of his graduation in dredging

Suman has been concentrating on gathering the various models for wear under different conditions during his own graduation. The results from his simulations could only be checked against my own experience with badly worn impellers and disasters. Immediately introducing observer bias and survivor bias. So, for this project Suman really wanted to include experiments to have at least one observation to match the simulations.

Damen slurry test circuit with dredge pump and impeller
Damen slurry test circuit with dredge pump and impeller

And what a struggle it was, to get the experiments done. Wim really gained more experience in fixing troubles than in fact finding. In the end he managed. After operating for a couple of weeks under heavy load conditions for the dredge pump, the impeller showed a noticeable wear pattern. And they came up with an innovative way of measuring the erosion pattern and match the test results with the simulation results.

Comparing CFD results (l) with measured erosion (r)
Comparing CFD results (l) with measured erosion (r)

The paper Suman is going to present on the WODCON, condenses the results from Wim together with Suman’s previous work as a graduation student himself. Don’t get deterred by the in depth analysis. If you fancy, you can follow the comprehensive literature references and understand his model. Or, just enjoy the ride and inspect the interesting pictures with the conclusions at the end. If you are really interested in his work, just approach him in the break hours, he is very willing to share his experience with you.

If you can’t find him, or Rick. Drop by at our booth #27 in the lobby.4 There will always be someone to get you into contact.

Damen invitation for the WODCON 2022
Damen invitation for the WODCON 2022

References

  1. WODCON 2022, WODA
  2. Graduation Suman Sapkota: Where Wear Parts Were Worn Down, Discover Dredging
  3. Graduation Of Wim Kleermaker: Measuring And Predicting Wear In Impellers
  4. WODCON Dredging Conference, Saskia den Herder

See also

Personal Announcement: Going Back To School To Cut Some Clay

Learning early or later in life, studying is always a joy when you make it practical
Learning early or later in life, studying is always a joy when you make it practical

‘Never too old to learn’ is my motto. Everyday I look around me and I wonder how this beautiful world fits together. Whether it be the stars in the sky, the waves at sea or life as we know it, there is always something to be learned about it. At school, I was not a great pupil, but I was always curious to learn more. For my master thesis at the Delft University of Technology, I investigated the performance of a dredge and made recommendations to improve its operation1. As the project was more focussed on mixture forming (and turbidity) and the redesign of the auger head, there was no attention for the soil mechanics involved in the cutting process.

Fully covered cutter head in sticky clay

Now is the time to get that straight. In my daily business, I came across several projects where the clay cutting was a real problem. This was one of the triggers that sparked my interest in sticky clay and made me pursue a more detailed investigation into this nasty stuff. I am very grateful my management was willing to grant me time to go back to the university and start a PhD project with professor Cees van Rhee to learn more about clay.

Synthesis of clay and the relevant properties for dredging

Clay is a completely different material than sand or rock. Those are either plastic and non-cohesive or elastic and cohesive. Clay is the worst of both worlds: plastic and cohesive. It can be described with certain soil parameters as e.g. undrained shear strength and internal friction angle. The failure model is based on Mohr’s circle etc. But those are all continuum approaches2. When you zoom in to the particle level of clay, a whole new world opens up. I already wrote about the interesting particle interaction in a previous post3.

Boltzmann strain rate function in clay cutting
Boltzmann strain rate function in clay cutting

It appears, that the consistency, deformation and failure of clay is related to the tiny electric charges distributed over the platelet crystals. The movement along the charges needs energy. The model to describe dislocation energies along electric charges has been studied by Ludwig Boltzmann4,5. His model governs a wide range of applications, ranging from cosmology to particle physics. I really plunged into the deep end of science with just simple clay. It already took some time to get my head around the concepts involved. Slowly it dawns on my what possibilities there are to improve our understanding of the cutting of clay and possibly to improve our products eventually.

Gallery of my dredging professors (l) prof. de Koning, (m) prof. Vlasblom, (r) prof. van Rhee
Gallery of my dredging professors (l) prof. de Koning, (m) prof. Vlasblom, (r) prof. van Rhee

My ‘old professor’ de Koning was a proponent of ‘thinking with your hands’6. Professor Vlasbom encouraged me to graduate on a practical problem and also my current professor van Rhee suggested to do some preliminary experiments with sticky stuff to get some feeling about what I am going to study. Of course I took some clay home to play with it. But the best suggestion was by my colleagues, who thoughtfully gave me stroopwafels7. The ultimate representation of sticky non-Newtonian stuff between layers of latticed disks.

Fresh supply of stroopwafels for practice and celebration
Fresh supply of stroopwafels for practice and celebration

References

  1. Presenting Pump Power Peculiarities, Playing With Pumps And Pipes, Discover Dredging
  2. The Cutting of Sand, Clay and Rock – Soil Mechanics (6041), TU Delft
  3. The Origin of Clay, When Dredging Becomes Sticky, Discover Dredging
  4. New Developments Of Cutting Theories With Respect To Dredging The Cutting Of Clay, SA Miedema
  5. Ludwig Boltzmann, Wikipedia
  6. Experience the Dredging Experience
  7. Stroopwafel, Wikipedia

See also

Second Thoughts On The Energy Transition Panel At the Latest CEDA Dredging Days

Energy transition panel discussion CEDA Dredging Days 2021 (Credit: CEDA)
Energy transition panel discussion CEDA Dredging Days 2021 (Credit: CEDA)

The CEDA Dredging Days are long gone1. Maybe some of you still have a faint memory of the innovative online event. After this event I was quite occupied and not able to do a proper review. I did even miss the opportunity for the traditional new years welcome post. My apologies, more to that another time. Concerning the Dredging Days. I still kept some nagging thoughts about the Energy transition panel discussion that I want to share with you. And the recent invitation for participating in the CEDA Commission on Decarbonisation is another good motivation2.

On the second day of the conference there was a session with a panel discussion on the ‘Energy transition in the dredging industry’. Several experts in the dredging community were invited to present their perspective on the energy transition. From the legislation side (Dagmar Nelissen, CE Delft), clients (Joris Vijverberg, Rijkswaterstaat), suppliers (Benny Mestemaker, Royal IHC) and contractors (Sven Kramer, Van Oord). The panel was moderated by Paul Vercruijsse from the CEDA Working Group on Energy Efficiency3.

The take-aways of the panellists were amongst others: ‘No single solution for all, Transitional fuels should be flexible, Transition should be facilitated by regulation, There might be a financial objection to change.’ Along these lines, there were polls on the perspective of the audience. The response to two of the polls surprised the panellists.

Results on the polls for rate of transition (l) and preferred energy carrier (r) (Credit:CEDA)
Results on the polls for rate of transition (l) and preferred energy carrier (r) (Credit:CEDA)

As I was present there, I have my own perspective on the discussion. First the rate of transition. The panel was surprised that the audience was expecting a transition ahead of the IMO planning. I was responding to our own national situation. Currently I see so some initiatives to convert dredges and projects to electric drives, that it could be possible4,5,6. But I expect to see a next generation of newbuilds soon that will be virtually or completely decarbonized.

Well to propeller emissions (Credit: CEDA)
Well to propeller emissions (Credit: CEDA)

The other surprise is was the preference for hydrogen as the final fuel of the future. Although all the alternatives do have better performance, are easier to store or downright cheaper according to the experts in the panel. That might be very well, but I think the answer is in the presentation by Benny Mestemaker. It will simply be the fuel with the lowest emission to supply and use. In the end we will have to go to that dot on the horizon. And I do see other advantages where my opinion differs from the experts. The complaints of the panel was the complete lack of infrastructure for hydrogen at both the project sites and the vessels themselves.

Concerning the infrastructure near the project site. Yes, there are no installations yet. However, the thing is. You can find renewably generated hydrogen everywhere. As long as you have access to sun, wind and water. And that is exactly where most dredging projects are happening. Off course, there is no factory yet, but that is outdated philosophy. There will be movable plants available that will create a new market. e.g. I am very hopeful of initiatives like ‘Solar Duck’7. They can roam the projects delivering tailor made hydrogen production, right where you need it.

Floating solar power plant (Credit: SolarDuck)
Floating solar power plant (Credit: SolarDuck)

Concerning the vessels. Yes, the installation to sail the vessel on hydrogen will take up a lot of valuable cargo space. But, that is no technical problem. We’ve had technologies that required an even bigger chunk of the vessel deadweight: coal burning steam ships. The big equalizer is: there was no other solution. Everybody was using it. And that is the same here. I think there will be no other solution than to use hydrogen, as it is completely emission free. One of my perspectives on design choices: select the solution that you know will solve the problem!
Transition schedule to convert to fossil fuel free dredging equipment

Transition schedule to convert to fossil fuel free dredging equipment
Transition schedule to convert to fossil fuel free dredging equipment

References

  1. CEDA Dredging Days 2021, CEDA
  2. Invitation to CEDA Commission on Decarbonisation (CCD), CEDA
  3. CEDA Working Group on Energy Efficiency (WGEE), CEDA
  4. Transitiepad Kustlijnzorg en Vaargeulonderhoud, Rijkswaterstaat
  5. Zero Emission Dredging Hub van start, EDB Drechtsteden
  6. Complete zandfabriek zo hoog als een flatgebouw dobbert ineens in de voorhaven van Deest, De Gelderlander
  7. Electrifying the world with offshore floating solar, SolarDuck

See also

We Choose To Adopt Energy Transition, But How Will We Succeed?

Comment

CEDA will provide access to the panel discussion shortly. Dredging Days attendees can still (re-) watch it on the conference platform.