Woudagemaal to get a digital simulator

The Ir. D.F. Woudagemaal in Lemmer has acquired a virtual twin this summer. De Ingenieur visited the digital simulator of the historic steam-powered pumping station, which pumps excess water from the Frisian polder into the IJsselmeer during periods of flooding.

Inside the Woudagemaal in Lemmer, Friesland, stands an operator with a controller. He navigates smoothly through a space on the screen that looks exactly the same as the room we are in – it is reminiscent of the Droste effect.

Everything is rendered as realistically as possible, from the tiles on the walls to the sunlight streaming in. We are standing beside a simulator of the historic steam pumping station, developed by staff at the Maritime Applied Research Centre, part of the Academy Tech & Design at NHL Stenden in Leeuwarden. This will soon enable trainee stokers and engineers to be trained without the real Woudagemaal having to be (literally) fired up. They will look at a screen and then be able to operate the virtual pumps and steam boilers in the simulator. ‘Training on a real, operational pumping station remains necessary, but the virtual training programme is a cost-effective and sustainable addition,’ said Dike Reeve Luzette Kroon of Wetterskip Fryslân at the ceremonial opening on 8 July.

Used more frequently

The Wouda Pumping Station dates from 1920 and has been on the UNESCO World Heritage List since 1998. It is the largest steam-powered pumping station still in operation in the world. Not that it is switched on very often; usually it is only about once or twice a year, following a period of heavy rainfall. At such times, the pumping station helps to keep Friesland dry by pumping excess water into the IJsselmeer.

But the climate is changing, and as a result, heavy rainfall is becoming increasingly common. Consequently, the Woudagemaal is in operation more frequently. In the winter of 2023/24, it was even in operation for 27 days. For this reason, Wetterskip Fryslân wishes to increase the number of teams capable of operating the machinery from three to four.

Normally, these shift teams undertake practical training twice a year for a week, in the autumn and in the spring. The pumping station is specially brought up to full capacity for this purpose. This consumes around twenty thousand litres of biofuel per week. Thanks to the simulator, training can take place more frequently and in a more sustainable manner. ‘And more safely,’ says Jan de Jonge, senior researcher at the Willem Barentsz Maritime Institute at NHL Stenden. ‘You can simply make a mistake or see what happens in extreme situations. If you do that in real life, the historic machinery could break down.’

Old technology

Simulators are increasingly used for training purposes, for example in shipping or in pilot training. But the digital replica of the Woudagemaal is particularly special, says Jeroen Rijnhart, director of the Academy Tech & Design at NHL Stenden, at the opening ceremony. With ships and aeroplanes, the technology is often already computerised, and creating a simulator is simply a matter of sending signals to virtual rather than physical machines. ‘You can then make them respond to those signals in the same way.’

In the case of the Woudagemaal, however, the installations date back to the first industrial revolution and utilise oil-fired steam engines. Their movements depend, amongst other things, on temperature and pressure. Converting that into a digital version requires a much deeper understanding of the underlying processes and far more calculations.

Realistic simulator

The simulator combines realistic-looking, interactively moving 3D images with a computational model of the thermodynamic mechanisms taking place in the pumping station. All components of the pumping station are included, including boilers, machinery, a ring main, pumps, condensers, filter tanks, burners, rockers, flywheels, a camshaft and valves. The user can walk around, read gauges, light burners, open and close valves, look at the fire through hatches, top up the water, and more.

De Jonge developed the simulator’s calculation modules. To do this, in addition to his knowledge of physics relating to the underlying thermodynamics, he also used data from a 1925 publication by Professor of Mechanical Engineering Johan Dijxhoorn in *De Ingenieur*, concerning the machinery at the Wouda Pumping Station. He supplemented this with new observations made at the pumping station itself.

‘Dijxhoorn’s article focused mainly on the phase when the pumping station is running at full capacity and is under steam,’ he explains. ‘But nowadays it is used so infrequently that the start-up phase is also of great importance.’ The simulator’s development team has therefore been regularly present during the pumping station’s start-up over the past year and a half. They also made use of drawings, scans, photographs and videos.

The final model, programmed in Python, simulates the behaviour of the Woudagemaal in response to user actions and as a function of time. Every second is divided into one hundred time steps, and in each time step calculations are carried out for the flow rates, temperatures, pressures and enthalpy values of the fuel and steam, as well as the resulting movements within the pumping station. This determines how much steam and energy is required at each location.

If the engineers and stokers manage to supply the virtual machines with these in good time, the simulated power station will run smoothly. And if things do happen to grind to a halt, there’s – apart from perhaps a fellow student or lecturer – absolutely no one who’ll notice...