• Kokgemaal near the windmills of Kinderdijk
Kokgemaal near the windmills of Kinderdijk

Bakker Sliedrecht modifies Kokgemaal for more efficient draining of the Alblasserwaard

05 February 2021

Bakker Sliedrecht has equipped auger 1 of the Kokgemaal near the windmills of Kinderdijk UNESCO World Heritage with a new electric motor and frequency drive. This modification enables the Rivierenland Water Authority to use the water pumping station vibration-free and more efficiently when draining the Alblasserwaard.

The Kokgemaal consists of three augers with a diameter of 4.5 meters, with a combined capacity to pump away 1.54 million liters of water per minute out of the drainage-canal of the Overwaard, the northern and southern part of the Alblasserwaard. In this way, the water level in the polder is maintained. The drained water is pumped into a basin in front of the Elshout lock, from where the water flows further into the river Lek.

Increased efficiency of Alblasserwaard drainage system

The water pumping station was put into service in 1995. The water authority wanted to be able to use the three augers more efficiently. Until now, the three drive motors could be off or run at 100 percent power. By replacing the old electric motor of auger 1 with a new one with a frequency drive, this auger can now be used at 0 to 100 percent power. This creates more options to run the entire pumping station at the desired capacity. “The pump station can be operated with more flexibility. In the past, there were three options by switching an auger on or off each time. Now the first auger can run at 30 percent, for example, or can be switched on partially when the other two are operational. That makes draining the Alblasserwaard a lot more efficient,” explain account manager Ruud Springvloet and project manager Arie de Jong of Bakker Sliedrecht. In addition, the vibrations in the engine foundation appeared to be out of range.

Successful project delivery

Installing a new foundation prevents vibrations that make noise and cause damage to motor and auger in the long term. The task was complicated because of the tilt of the entire installation. Bakker Sliedrecht dismantled and disposed of the old installation, supplied and commissioned the new one and carried out all tests and inspections. After some final details, the project was successfully completed at the end of January. “It was a relatively new project for us. We know everything about electric motors, frequency drives and cabling, but not much about foundations. An external expert helped us with that,”, say Springvloet and De Jong.

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