Tag: WODCON

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

Historical Origins Exhibition at the WODCON: Yu the Great

Statue of a bronze Ox, commemorating Yu the Great.
Statue of a bronze Ox, commemorating Yu the Great.

Traveling all the way to the WODCON in Shanghai China1 presented an excellent opportunity to visit this wonderful country. So, after the congress, we travelled to Beijing, to visit the tourist highlights. However, as obsessed with dredging as I am, I can find inspiration for the stories on this website anywhere. Take for example this bronze ox. Quietly staring at the Summer Palace2, it might easily be overlooked by the innocent visitor. But it is very relevant for our dredging community. It is to commemorate the great Yu, who subdued the flood with the first dredging project in the world3.

Exhibit about Yu the Great at the historical origin show at the WODCON 2019.
Exhibit about Yu the Great at the historical origin show at the WODCON 2019.

Next to the interesting presentations and the conventional dredging exhibition, the WODCON organisation arranged a nice little exhibition on historic origins of dredging in China. Of course the first exhibit was about Yu. Intrigued by this little piece of information, I asked around and did some research on the internet to puzzle together, what the sign did not tell.

First of all, there are that many records4. It has been so long ago, there only remains oral tradition to consult. The facts are inconclusive, even claiming it is just a mythical tale. So, we will approach this Mythbuster style. Examine the myth and the facts. Test it. And if it does not provide the expected results, take it to the extreme. Unfortunately, we will not blow things up at this time. Maybe we will do that later on another topic.

Sign at the bronze ox at the Summer Palace, Beijing.
Sign at the bronze ox at the Summer Palace, Beijing.

The story depicted on the information sign is not completely in line with the historical data available. Let’s start with the ‘iron’ part of the ox. According to several sources, the adventures of the Great Yu may have happened 2000BCE. That is in the middle of the Stone Age5, at best early Bronze Age. Also, it was usually not ‘to ward of the floods’. Those were mitigated by a framework of dikes, dams and overflow weirs6. When an ox was mentioned, it is about protecting these civil works. But nowhere can I find a solid explanation about what an ox can do to protect a dike or how this procedure would contain the river in its human designed trajectory.

Water buffalo at the Li River, near Yangshuo.
Water buffalo at the Li River, near Yangshuo.

Even today, one can find bovine creatures standing in the river. And from a distance they might easily be mistaken for a field of boulders. Conversely, a field of boulders might also be mistaken for a herd of oxen…

Boulder field or rudimentary groyne in the Li River, near Yangshuo.
Boulder field (or rudimentary groyne?) in the Li River, near Yangshuo.

So, my hypothesis is: ‘the Great Yu constructed his dikes and protected them with groynes against erosion7. When the uninitiated had to describe what he constructed, they compared those with water buffalo and the oral tradition morphed this into iron oxen.’ This is only my opinion after just a little research and it is up to educated historians with their research to disprove it.

Discussing these civil works and the containment of rivers, made me think of my beloved home country through the famous Dutch poem ‘Memories of Holland’8.

Excellent masterpiece of hydraulic engineering to contain a river and example of modern groynes. (Credit: van den Herik-Sliedrecht).
Excellent masterpiece of hydraulic engineering to contain a river and example of modern groynes9. (Credit: van den Herik-Sliedrecht).

References

  1. WODCON, Damen
  2. Summer Palace, Wikipedia
  3. Great Flood (China), Wikipedia
  4. Yu the Great, Wikipedia
  5. History of China, Prehistory, Wikipedia
  6. Chinese Myth of the Deluge, China Heritage Quarterly
  7. Groyne, Wikipedia
  8. Herinnering aan Holland, David Reid Poetry Translation Prize
  9. Kribverlaging Waal Fase 3, Van den Herik-Sliedrecht

See also

My WODCON 2019 Presentation: Launching Robotic Dredging

Me, presenting my WODCON 2019 contribution.
Me, presenting my WODCON 2019 contribution.

Yesterday, I gave my presentation at the WODCON 2019 in Shanghai1. The WODCON is the triannual world dredging conference, were everybody in the dredging industry meets and exchanges knowledge and ideas. Just as I mentioned in my New Year’s post, I sometimes like to delve into some old archives, get inspiration and hatch new ideas2. So did I for this presentation.

Overview of the ‘Ketelmeer’ (Credit: Google Maps).
Overview of the ‘Ketelmeer’ (Credit: Google Maps).

A seminal dredging project concerning environmental dredging is the ‘Ketelmeer’ clean up dredging project, resulting in the creation of the contaminated sediment storage depot in the artificial island ‘IJsseloog’3. As careful removal of the contaminated sediment required novel dredging techniques, the government challenged the dredging industry to test four innovative concepts. The results were evaluated by the institute now called ‘Deltares’ and published in a report4. The original conclusion of the report was, that the auger dredge was the best in reducing the turbidity. Later, the bigger auger dredge ‘HAM291’ was constructed and used to actually clean up the lake. With the knowledge and the experience of the auger we also developed a range of auger attachments for our DOP pumps5.

Traditional auger attachment for a DOP pump excavator combination.
Traditional auger attachment for a DOP pump excavator combination.

Reading the Ketelmeer report again, it occurred to me, that one parameter had not been properly accounted for: the size of the dredge. The auger dredge was by far the smallest dredge in the game. With a weighed scoring method, the dredges were also compared in size and installed power. The reasoning is that a bigger dredge has more interaction with its environment. Naturally, the environment gets more disturbed and turbidity levels should be higher for a bigger dredge. And the data was there to support this hypothesis. Smaller is better! Still, this does not undermine the initial results of the concept, as that was evaluated for turbidity per cubic meter. The bigger dredges also delivered more production. But when comparing dredges of the same concept might the smaller ones will perform better on turbidity. And this is in accordance with our experience. Every project where we’ve supplied these auger dredge units, the contractor and the client where surprised and happy about the achieved turbidity levels. Now, we know why: smaller is less turbidity.

The next step in performance might be reached by further decreasing the size of the dredge. However, the DOP is already as small as it is for a viable application on an excavator. The conclusion is to have an auger operating directly on the bottom: an unmanned submarine dredging machine!

Possible general arrangement of a robotic dredge submarine.
Possible general arrangement of a robotic dredge submarine.

This machine should navigate by itself and self-supporting. The wear parts of the auger should be exchanged by itself and solar panels can provide extra energy for extended missions. It has only a small hopper and discharge should also be done quick and automatically. An unmanned barge or even a dump truck trailer at the shore of the waterway can be replaced at longer intervals. Obstacles and other tricky spots can be alerted to a human supervisor for later intervention. One machine alone does not have an impressive production. The real power is in applying them in numbers. As we are standing on the brink of a revolution in robotics and artificial intelligence, this scenario may be not as farfetched as from your first impression. Imagine a whole school of these mechanical fishes cleaning up your waterway, while you sleep…

Working method of robotic dredge submarine (Credit: Judith Korver).
Working method of robotic dredge submarine (Credit: Judith Korver).

References

  1. WODCON, Damen
  2. New Year’s post 2019, Discover Dredging
  3. Ketelmeer project, Wikipedia
  4. Rapportage baggerproeven Ketelmeer. RIZA Rapport, 97.023, ISBN 9036950708
  5. DOP Pumps, Damen

See also