Our Interview About New Pump Designs In The Latest Damen Nieuws

Headline of our interview in ‘Damen Nieuws’
Headline of our interview in ‘Damen Nieuws’

Another magazine dropped on my doormat, albeit a digital edition of ‘Damen Nieuws’1. The internal magazine for Damen colleagues. It featured an article with Suman Sapkota and me. Suman is our pump design specialist2 and at a Damen wide R&D convention he presented a poster on his pump design workflow within Damen Dredging Equipment. This caught the attention of the editorial board and we were interviewed on what we actually do for a living. Although we can’t share the exact details of the article or the poster, it is still an interesting message that we can highlight here.

Pump design workflow (inspired by Suman Sapkota)
Pump design workflow (inspired by Suman Sapkota)

The design of a dredge pump is based on the required specifications(1). The most important properties of the pump are: efficiency, NPSH, wear and ball passage. The first important property we try to fix is the ball passage3. We do use our own geometry generator(2) that assist us in creating a pump with a big ball passage. Unlike normal pumps, dredge pumps have to cope with debris and boulders that have to pass the impeller. The bigger chunks that can pass, the more uptime the dredge will have. Once we are satisfied with the geometry, we feed this through a file format converter(3). The resulting 3D file can be used on several platforms. This will enable us to create the digital solid for the engineering4, but it also gives us the negative volume, also known as fluid. Then to do mathematical operations on the digital fluid, we have to divide the volume into tiny cells. This process is called meshing.(4) When the mesh is available, the fluid flow through the mesh can be simulated with computational fluid dynamics.(5) All the fluid properties of every cell are calculated and the results are shared with the adjoining cells. This can be repeated until all properties of the cells don’t change very much anymore, a stable solution. Integrating all the properties of the cells give the resulting performance of the pump.

Balancing the four dredge pump performance properties
Balancing the four dredge pump performance properties

The estimated performance can be evaluated against the four properties.(6) The head times the capacity divided by the power required will give the efficiency. That is one of the items we wanted to know, as it relates to how much fuel will be consumed. The other parameter obtained from the CFD is the NPSH, or roughly: the suction performance. Wear cannot be estimated yet, but we are working on that2. Although the calculated turbulence might give a clue what wear to expect. If the properties are not satisfying our requirements we make an iteration in the geometry for improving the performance. However, changing the geometry will usually result in a smaller ball passage. If the parameters are OK to our requirements we have a pump design.(7) Manufacturing it is a completely different game.5

The design process of the dredge pump takes quite some effort and we are continually looking to improve the workflow6. Eventually we would like to be able to cater for all special requirements each individual customer might have.

Working for a dredge manufacturer, I am happy we design and produce our own pumps. It gives us the confidence, that when we supply dredges, they are as we like them to be. Another benefit is in discussions with the customer. It is easier when we can sit at the table as experts on their equipment assit them in finding a solution for their dredge.

Pump experts immersing themselves in checking the design of their pumps
Pump experts immersing themselves in checking the design of their pumps

References

  1. Damen Nieuws, Juni 2020, Damen
  2. Graduation Suman Sapkota: Where wear parts were worn down, Discover Dredging
  3. On The Relation Of Maximum Ball Passage And Recirculation Losses In Dredge Pumps, WODA
  4. Graduation Of Carsten Markus: Designing And Casting Of Impellers
  5. Don’t Play Games With Your Wear Part Planning
  6. Innovation, Damen

See also

The Good Side And The Bad Side Of A Statue At Port Said

Statue of Ferdinand de Lesseps in a garden at Port Said Shipyard
Statue of Ferdinand de Lesseps in a garden at Port Said Shipyard

As you’ve probably already guessed, I am quite fond of old stuff. Especially when it has some relation to dredging. Last post on Omar’s graduation1 not only brought back my memories on the interesting lectures by professor de Koning2, it also rekindled my inspiration to write about something that I have up my sleeve for a long time already. Although, due to the current global turmoil3, the message that I want to convey has been drastically altered. It turns out to be more of an opinion than an informative perspective on the history of the Suez Canal.

It was in the early years of my career, that I was building dredge ‘10th of Ramadan’ for the Suez Canal Authority4. We designed the dredge and prepared the components at Damen Dredging Equipment5, but the actual construction took place at Port Said Shipyard6, a subsidiary of the client. I’ve spent many hours roaming over the yard to locate components that were sent there and we needed them to inspect or install. On one of those excursions, I encountered the statue of Ferdinand de Lesseps.

Ferdinand De Lesseps was an interesting figure7, who owed his success to being the right person at the right time at the right place. In his earlier career, during a quarantine period in 1832 in Alexandria, he received a book that discussed Napoleons ideas about connecting the Mediterranean with the Red Sea8. Captivated by this idea, he was able to use his connections and positions to get the concession to dig the canal as we know it in 1859. In honour of this achievement a impressive statue was placed at the beginning of the Canal at the Port Said side after the opening in 1869.

As it happened in those days, the Compagnie Universelle du Canal Maritime de Suez, claimed the canal and all involved land and business for the French government. All revenue from the Canal ended up in France and not in the country that had worked so hard for the Canal. This has been a great disappointment for Egypt. When Nasser declared the Suez Canal a national property in 1956, the statue was removed as a gesture that Egypt was independent and no European country had any business ruling it as a colony. In a careful act of historical awareness, the statue was not destroyed, but placed at the Port Side Shipyard to be taken care of until the future would find an appropriate purpose. There it is kept in honour by a select group of craftsmen, who depend for their subsistence on his legacy.

Statue of Ferdinand de Lesseps at the entrance of the Suez Canal (Credit: Google)
Statue of Ferdinand de Lesseps at the entrance of the Suez Canal (Credit: Google)

In 1956 it was not so much vandalism by the people that the statue was removed from public space.7 It was a statement by a public conscious government with history awareness that prevented further harm from mindless destruction. Now, over half a century later, we see more acts of iconoclasm to historical statues, and then in a so called civilized world… A lot of historical figures were children of their own time. And for sure, those times were not very civilized in hindsight. OK, I am history aware and enjoyed my history lessons. There I had to learn that the raids of the barbarians on Rome, the Crusades to occupied Jerusalem and the iconoclasm in our own Reformation era were to be condemned. So, imagine when a lot of historical figures were removed from the street by emotional destruction, would later generations not condemn us in turn? What I would find even worse, is that future generations would not be aware of the dark side of those old ages as there are no statues to remind them to it. Maybe we can reintroduce a penalty for those ‘heroes’ from their own days: ‘the pillory’9. Just as with all sentences, the penalty can only awarded by the government, or an appointed committee, not the public. If that fails, store them under the custody of people who take good care of them without reverence. And at least let the pedestal remain to remind people of their history. ‘Those who cannot remember the past are condemned to repeat it.’ (George Santayana)10

Possible implementation of a statue with a pillory sign?
Possible implementation of a statue with a pillory sign?

References

  1. Graduation Omar Karam: Rock Cutting The Egyptian Way, Discover Dredging
  2. Boundary Conditions for the use of Dredging Equipment, Lecture notes i82 A+B, prof. J. de Koning
  3. Violence and controversies during the George Floyd protests, Wikipedia
  4. The Ancient History of the Cutter Suction Dredge ‘10th of Ramadan’, Discover Dredging
  5. DTC – Think Global, Act Local, Damen Shipyards
  6. Port Sid Shipyard, Suez Canal authority
  7. Ferdinand de Lesseps, Wikipedia
  8. Mémoire sur la communication de la mer des Indes à la Méditerranée par la mer Rouge et l’isthme de Soueys (p.352), Google
  9. Pillory, Wikipedia
  10. George Santayana, Wikiquote

See also

Graduation Omar Karam: Rock Cutting The Egyptian Way

Graduation presentation of Omar Karam
Graduation presentation of Omar Karam

Egypt is a great nation when it comes to ancient engineering. No other country has such a concentration of impressive monuments and such an interesting history as over there. If you are not convinced that modern Egyptians are not capable of great engineering feats you are wrong. Last Monday, Omar Karam graduated at our R&D department of Damen Dredging Equipment1 on his thesis about ‘CSD Rock Cutting.’

Cutting processes have been extensively described by Sape Miedema in ‘The Delft Sand, Clay & Rock Cutting Model’2. Omar has been using the frame work of Miedema to make some useful tools for the estimation of the production of our dredging equipment in rock. In due time, you will find the results of his thesis in the online dredge selection tool ‘Sandy’. Omar’s curiosity and ingenuity does not end here. He will continue studying at a university, but I do hope to meet him again, as he would be a valuable asset for our dredging community. Keep an eye out for him.

Program structure diagram of cutting force calculations
Program structure diagram of cutting force calculations

His graduation brings me back to my first lessons in dredging technology at the Delft University of Technology by the illustrious professor de Koning. In a sense he was an old school engineer, who hammered it in to us that thinking is done by doing it with your hands3. Back than the Polytechnic School was just rebranded to University and he was mocking that as a university, we had to set the topics in a broader perspective. So, he started his introduction on cutting technology with some slides of the unfinished obelisk at Aswan4 as every aspect of the cutting process could be illustrated.

Phases of chip forming in rock cutting
Phases of chip forming in rock cutting

The story according to de Koning is: ‘Around the quarry of the obelisk, they have found diorites5. These are some sort of volcanic balls of rock. In combination with the marks and scratches all around the obelisk, archaeologists believe these stones have been used to pound the granite. The impact compresses the bedrock and the resulting stresses fracture the contact surface(1). For every hit a whiff of dust is created. Eventually the dust is collected and scooped away for the next layer. Next, trees would be planted in the trench on one side of the obelisk. The growing root system displaces volume and create shear stress underneath the obelisk that would sever the obelisk from the bed rock(2). At last the trees are removed and dry wooden dowels would have been inserted in the shear cracks. Saturating the wooden dowels will make them grow. The last strands of rock will now be broken due to tensile stresses(3). Repeated insertion of new dry dowels and saturating them will lift the whole obelisk enough to pull some ropes under and carry the obelisk away to the building site.’

Although the diorites and the scratch marks are a smoking gun, current archaeologists argue about the feasibility of this process as experiments yield a very low production and it is doubted that the obelisk could be finished in the lifetime of the client6. Even if disputed, de Koning told a story that conveys the message; I vividly remember it and makes me understand the rock cutting process.

These mysterious monolithic ornamental spires have been an inspiration for many legends and stories. When we have solved the riddle of the rock cutting with diorite balls, it may inspire the development of new rock cutting technology for the dredging community and we can put the story of the obelisks to an end.7

End of the story on the cutting of obelisks (Credit: Uderzo)
End of the story on the cutting of obelisks (Credit: Uderzo)

References

  1. Innovation, Damen
  2. The Delft Sand, Clay & Rock Cutting Model, TU Delft
  3. De Koning (1978), Denken met de handen’, TU Delft
  4. Unfinished obelisk, Wikipedia
  5. Diorite, Wikipedia
  6. The Unfinished Obelisk, NOVA
  7. Asterix and Cleopatra, Goscinny-Uderzo

See also