Anglian Water ends long search to improve pump station efficiency
After nearly six years, Anglian Water has finally found a solution to improve efficiency at one of the largest raw water pumping stations in England.
In 2016, the company commissioned engineering solutions provider Boulting Group to optimise Empingham Pumping Station. Located in the county of Rutland, Empingham receives water from two upstream pumping stations to fill Rutland Water, the largest man-made reservoir by area in the UK.
Despite several upgrades since its construction in the 1970s, station performance wasn’t ideal and required high levels of maintenance due to years of control changes and modifications. Anglian had identified many of the problems but needed technical support and was clear that a special mix of skills was required: operational pumping systems knowledge coupled with instrumentation and control capability.
Boulting, having been approached to undertake an opportunity-day survey and gather historical data and information on the site, established that the pumps were in good condition and that the control system was at the heart of the problem.
A Front-End Engineering Design (FEED) study followed to identify the full scope of work, and the main objectives Boulting identified were to achieve a predicted annual energy saving of £120,000, reduce maintenance and increase resilience by making the pumps more reliable.
The project was to be installed during the winter months – a crucial time as maximum pumping is required to replenish reservoir levels. It was vital that no significant downtime was caused by the work as it would jeopardise reservoir storage targets for the following year.
“The original control system required a considerable amount of manual intervention and was produced in an out-of-date programming format that was difficult to modify,” Andy O’Rourke, Senior Consultant at Boulting Group, said. “The original pumps and motors required significant maintenance and the pump line-shafts had suffered several fatigue failures, attributed to repetitive changes to speed.
“We implemented an intelligent level-control philosophy, which passively balanced the system without constant intervention and eliminated low speed operation and regular changes to speed. This was imperative for the older motor designs, which can suffer accelerated motor brush wear, and ensured the pump seals and line-shafts were adequately protected. There were also non-return valve improvements that eliminated back-flow and wasted pumping energy.
“The pumps were a mixture of fixed and variable speed units of varying sizes, voltages and technologies. Because of these variants, three different control strategies were implemented and activated depending on how many pumps of each type were available. The overall control was proven to successfully operate any combination of pumps with no degradation to performance.”
Boulting created a full simulation of the control system allowing Anglian to test and interact with the new system during its development.
Chris Evans, Energy Efficiency Manager at Anglian Water, said: “The use of a simulation was an integral part of the solution. It was so successful that the flow rates being calculated from the pump speed and pressure were included as part of the main control to act as a standby to the real flow meters.”
Evans said the work has exceeded expectations, “achieving an energy reduction saving of around £150,000 per annum and associated reduction in carbon emissions,” and added: “We are now spending less money on maintenance and the probability of asset failure will have decreased. The pumps underwent a considerable amount of wear and tear previously, which was caused by the systems continually stopping and starting.
“Due to the success of the work conducted by Boulting Group at Empingham RWPS, we are looking at applying this approach to other large pumping systems in our region.”
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