Improving pump station efficiency
Anglian Water’s search for a solution to improve efficiency on one of its largest Raw Water Pumping Stations at Empingham is now over! The solution has now been found, and it has been proven.
In 2016, Boulting were commissioned by Anglian Water to optimise the Empingham PS, one of the biggest raw water pumping stations in the country. Located in the county of Rutland, Empingham receives water from two upstream pumping stations to fill Rutland Water, the largest man-made (by area) reservoir in the UK.
Since construction in the 1970s, the pumping station has undergone several upgrades. However, due to years of control changes and modifications the station performance wasn’t ideal and required high levels of maintenance. AW had identified many of the problems but needed technical support to develop a solution and resolve the complex issues at the station. To develop a solution, AW were clear that a special mix of skills was required, operational pumping systems knowledge coupled with instrumentation and control capability was essential within the same company as managing the relationship between two individual companies would have been a challenge.
Boulting were initially approached to undertake an opportunity-day survey and gather historical data and information on the site. The survey revealed that the pumps were in good condition and it was the control system which was at the heart of the problem.
Following the initial survey, Boulting were commissioned to undertake a Front-End Engineering Design (FEED) study to identify the full scope of work. The main objectives identified by the survey were to achieve a predicted annual energy saving of £120,000 per annum, reduce maintenance at the station and increase its 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“The original control system required a considerable amount of manual intervention and was produced in an out-of-date programming format that was difficult to modify. The original pumps and motors required significant maintenance and the pump line-shafts had suffered several fatigue failures, attributed to repetitive changes to speed” commented Andy O’Rourke, senior consultant at Boulting.
“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.”
“Prior to installation, Boulting created a full simulation of the control system to allow Anglian Water’s Energy, Operations and Telemetry teams to fully test and interact with the new system during its development. The simulation included real-time feedback to allow the station to be controlled virtually, allowing Anglian Water to visualise how the control would deal with any potential scenario. This collaborative process resulted in a system tailored to the needs of the end-user.”
“The project has been a great success, achieving an energy reduction saving of around £150,000 per annum and associated reduction in carbon emissions,” explained Chris Evans, Energy Efficiency Manager at Anglian Water.
“A lot of collaboration was necessary on this project. To develop a sustainable solution a large number of key people from Anglian Water had to be involved. 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.”
“Due to the complexity of the project, we wanted the required skills to be within the same company, so that system efficiency engineering, operational requirements and resulting control changes would be brought together. And It wasn’t just about technical know-how, it was vital the supplier worked closely with our Energy and Operational teams. We were looking for a supplier with people skills, not just one that would impose a solution. Boulting demonstrated all of this.”
“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 at Empingham RWPS, we are looking at applying this approach to other large pumping systems in our region,” concluded Evans.