Change your drive systems

22 January 2013

Water treatment and distribution company, SEMEA, has achieved a return on its investment over 14 months by replacing a pumping installation with a solution developed by Leroy-Somer and Flowserve.

Characterised by low rate variations, this application, initially at fixed speed, had little potential to achieve energy savings. As such, it is a good example that in many cases, changing a drive mechanism can offer benefits.

SEMEA wanted to replace a system made up of two motors and a pump which was used to supply a water tower.

Didier Heissat, sales manager for Flowserve in Nantes takes up the story: “With Leroy-Somer we carried out an analysis. We wanted to make sure that we could optimise the hydraulic result according to the pump characteristic. Each hydraulic installation works differently depending on the unit composed of the pump, the valves, and the pressure losses in the pipes. To be able to improve the energy efficiency, you need a pump characteristic curve which is not too flat. According to the results, we decided to integrate a new and more efficient pump. We selected a pump which forms part of our eco design approach and uses split case technology. It has a capacity of 500 to 1100 m3/hr. We also defined the best motor speed according to the pump capacity and the network”.

Pierre-Emmanuel Sarre, president of the Leroy-Somer Drive Systems division, takes up the story: “Leroy-Somer replaced the original two motors with a single permanent magnet synchronous motor with a power rating of 350kw and 1500 rpm speed. We also decided to control it with a PowerDrive MDS inverter to manage the variable flow rates, even if, in the case of SEMEA, flow rate is most often stable. This configuration is the result of the analyses and simulations we carried out. In parallel, complete tests were carried out with Flowserve to define the best pump efficiency point.”

Michel Labet, production manager at SEMEA, continues: “We could have simply replaced components reaching the end of their life cycle. For environmental and economic reasons, we preferred to consider a more optimised solution, even if it involved more time to establish the best option. Power consumption is reduced by 10% per cubic metre transferred. Moreover, the pump provides a higher water flow of 15%, which enables us to better benefit from the eight hour ‘night rate’. We gain two hours with the ‘daytime rate’. On the whole, the overall cost related to variable speed will be amortised in 14 months.”

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