18 energy efficiency
Pump and motor overhaul pays off
Following the renewal of the lock gates at Sluis Zemst in the Brussels-Scheldt Sea Canal, two pump installations were recently replaced. Accounting for a total flow rate of 18,000m3/hr, a 5% improvement in efficiency was achieved by clever coordination of the pumps with the motors. The custom-made pumps and motors were developed by pump supplier KSB and motor specialist WEG, as the companies explained to flow.
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he Brussels-Scheldt Sea Canal, popularly known as the Willebroek Canal, is one of the oldest canals in Europe. Today, it remains of great economic importance to Belgium. The airport of Zaventem is entirely dependent on a good throughput of the route for kerosene. Four locks manage the 14m drop in level along the route. The canal also plays a significant role in supplying Brussels itself, and in maintaining the water level of the local area. To guarantee the reliability of this important artery, the Zemst lock needed an overhaul. The lock gates were replaced, followed by pump installations to maintain the water level of the upper part of the lock. Jan van Laer, Senior Expert Water & Waste Water at KSB, explained how the decision to install completely new pumps had both technical and practical reasons: “Sluis Zemst had a total of five Ensival AGV15 pumps installed in the 1970s, which were no longer achieving their specified flow rate of 9600m3/hr. Three of the five pumps were in use and two in reserve, so that they could be switched on if necessary. But of course, you need to be able to rely on them all to perform so good maintenance is essential. However, Vlaamse Waterwerg NV, the manager of the lock complex, faced a challenge. Firstly, some spare parts had to be rebuilt; secondly, every maintenance request had to be put out to tender. So each time you had to deal with different parties. What’s more, when requests are put out to tender, the best technical solution does not always win, so the pumps sometimes ended up with poorer performance than they went in with.”
we compared various motors based on price, quality and efficiency. WEG came out on top here. Moreover, we know WEG and their motors well from other projects.” When asked about the pump characteristics that convinced Agidens to work with KSB, Jan initially mentioned their high efficiency. “Because in this application the pump only has one operating area – the fluctuations in water level are negligible – we could count on a fixed flow of 9000m3/hr and a fixed delivery head of 10m. We were then able to optimise the design for this. In this case, this resulted in an SEZ 1500 centrifugal pump with a semi-axial impeller with optimised blade angle, with high hydraulic efficiency of 85.1%. And because a relatively low speed of 500rpm is sufficient for these values, we were able to work with a 6kV medium-voltage motor.
“We could count on a fixed flow of 9000m3/hr and a fixed delivery head of 10m.”
NEW PUMPS Vlaamse Waterweg NV, therefore, decided to replace the pumps. This was also a tender, which was won by the engineering firm Agidens. Based on past experience, Agidens called in KSB as supplier of the pumps. They, in turn, chose WEG as their motor supplier. Jan continued: “For our proposal, Quarter 4 2019
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