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Riventa maximises output for hydro-turbine

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Riventa have been monitoring a hydro-turbine for a major water supplier in England, to see if its maximum possible electrical output was being maintained.
At a key site, river water is pumped to a break tank at the top of a hill, from where it can either overflow or run down the hill to a large reservoir below - or be directed to a hydro-turbine with the same outfall.
Riventa was tasked with monitoring the efficiency of the turbine in question – a fixed speed machine (1,016 rpm) that operates without any human intervention. Using inlet guide vanes, its load is controlled via flow rate modulation.
Riventa’s FREEFLOW hardware and software system was installed to show immediately whether a proposed change was effective or not.
The system also tracked any savings associated with a change and the financial consequences of it.
Originally rated with a best efficiency of 84%, the maximum detected was 82%. However, the turbine was found to spend less than 10% of its time above 80%.
Significant differences in power generated for the same flow rate were also observed.
For example, at 925l/s, the power generated varied between 185-260kW, showing an efficiency variation of 58-82% - thus demonstrating instances when 40% more power was generated for the same flow rate.
Working closely alongside its customer, Riventa looked at how to schedule the turbine for the best return within the operational constraints of the overall water network.
In highlighting whether scheduling changes were effective or not, the FREEFLOW system provided real-time tracking of any savings associated with a specific change.
The turbine was found to operate at an annualised average of 73% efficiency, but if increased to 80% this would translate to at least £11,000 ($15,000) per year savings – based on little or no capital investment.
Steve Barrett, managing director for Riventa, said: “This is a good example of how we can help identify opportunities to maximise output from a hydro application – with the same technology that we bring to pump and blower installations to help improve efficiencies, create energy savings and prolong the lifetime of assets.”