Yorkshire Water saves £61,000 on energy costs with ABB drives16 July 2013

Yorkshire Water's Esholt wastewater treatment works in Bradford is saving more than £61,000 per annum (25%) on energy costs, following installation of ABB variable-speed drives on its filter re-circulation pumps.

Three fixed-speed 180kW pumps were being used to transfer final effluent to the filter distribution chamber – operating as duty/duty/standby, and providing a flow of 1,000 litres per second under normal flow conditions.

But operational changes at the site substantially reduced the load to the filters, some of which have now been decommissioned, resulting in Yorkshire Water reviewing flow rates as part of its plan to cut electricity consumption by 7% by 2015.

Investigations revealed that the pumps were efficient enough, but led to suggestions that flows could be reduced to make an annual saving of £23,500. Detailed process calculations then revealed a potential saving of £50,800.

"Halcyon Drives are one of our preferred suppliers and we chose them for this project, because of convenience," states Mick Hawksworth, plant engineer for Esholt, adding that payback time would be well within the normal three-year requirement.

Halcyon installed 200kW ABB low harmonic variable-speed drives (VSDs) for all three recirculation pumps, replacing existing soft start units in the control panels and fitting insulated bearings on the pump motors to allow for the VSDs.

Once the installation was complete, which took four days, trials started, reducing the speed of the now VSD-driven pumps and monitoring the effect. The final optimum speed was 45Hz, enabling savings of £61,324.

Hawksworth: "As well as the main benefit of energy saving, the VSD project gives us more operational control. The flow is used as dilution flow and incoming loads could change in the future. Using the VSDs gives us the flexibility over and above simple fixed speed operation."

Brian Tinham

Related Companies
ABB Ltd
Halcyon Electrical Co Ltd

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