Optimising pump systems to reduce energy consumption

16 August 2022

Andy O’Rourke explains the role control optimisation projects can have in helping the industry to reduce energy consumption.

Pumps are fundamental in the water industry. They regulate the flow and pressure in pumping mains to ensure water reaches its final destination, whether that be a storage reservoir or direct to customers. Pumps also remove and enable treatment of wastewater.

One of the key ways to improve the efficiency of pumping systems and reduce energy consumption is through effective control optimisation. An intelligent control system will pump only the required water when needed, and at the optimum pressure. This approach will also improve the treatment process and resilience through reduced leakage and bursts. 

In delivering control improvements at Anglian Water, BGEN was responsible for a range of projects from conception to completion. Prior to each project taking place. Historical data from several sources was gathered and analysed to determine current and potential performance. A business case was then built to secure funding for the project. Finally, the project was closed-out by verifying the delivered energy reduction against predicted savings.

Examples of optimising control systems at Anglian Water included: Intake raw water pumping station: A desktop study was undertaken to evaluate the efficiency and energy reduction opportunities at an intake raw water pumping station. It had been identified that a lack of automation was impacting on performance. The pumps were also split between low- and high-pressure units. The low-pressure units were inefficient at high pressures and vice versa.

To deliver the energy savings a PLC was installed to provide automated control of the pumps, band-screens and valves to manage river and reservoir levels. This enabled calculation of the optimum target flowrate and to select the most efficient pump numbers and combinations (large or small).

Pressure optimisation: An intelligent control philosophy was designed by BGEN to smooth the demand on a major transfer pumping main. Modern variable speed drives were installed so that the pumps can reduce flow overnight (instead of completely stopping) to eliminate pressure surge and to better manage reservoir levels. This also reduced peak day flowrates and facilitated an optimised pressure/flow relationship, where the controlling pressure was calculated dynamically based on requirements.

Raw water pumping station: At another raw water pump station, it was identified that the existing control was inefficient and not making optimal use of the available assets. Due to the complexity of the system, a Front-End Engineering Design study was conducted to further analyse the system and verify potential savings.

To improve the efficiency of the station, BGEN used its Pump System Optimisation software which offers reduced energy consumption potential and storage volume management. As a result, the team optimised pump system flowrates, flow control and pump scheduling, which led to significant energy savings.

Making a difference
Through a number of control optimisation projects BGEN has achieved substantial carbon and cost savings for Anglian Water by reducing total emissions by 5,858 tonnes of embodied CO2 and total operating costs by £3 million. 

By embracing the potential of optimising controls water companies can make significant strides in tackling short-term energy prices and meeting long-term carbon reduction targets.

Andy O’Rourke is senior consultant at BGEN.

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