Water & Wastewater Treatment

PUMP CENTRE CONFERENCE & EXHIBITION 2015 PREVIEW 15 Pump system assessment generates energy savings Case study Technical Specifications Quantity: 2 Duty flow: 399 l/s Duty head: 51.5 m Pumped liquid: Final Effluent (fully treated sewage and storm water for Sea outfall) Pump type: BR12CL Energy Efficient Low Life Cycle Cost split case pumps Mounting: Vertical Open Shaft Casing material: Cast Iron Stuffing box sealing: Mechanical Seal Bearing lubrication: Grease Headpiece/stool material: Cast Iron S outh West Water has improved op- erational reliability, solved cavita- tion issues and reduced mainte- nance costs at a wastewater pumping station with help from the expertise of SPP's energy team. The utility made en- ergy cost savings of £105,000 – far ex- ceeding targets – a•er a system assess- ment revealed several possible efficiency improvements. South West Water had five SPP BR12 split case pumps installed in a waste water application. Having given good ser- vice over many decades, the pumps were dropping in performance, and a thermo- dynamic test revealed an intervention was required. The pumps were replaced by new SPP Low Life Cycle Cost split case pumps. They were specified with an operational efficiency of 92%, producing energy sav- ings of £78,755 - considerably exceeding the target of £30,000. The pumps were mapped to the system using thermody- namic assessment techniques, and were so successful that only two units were required, leaving two units as emergency standbys. However, the pumps developed mechanical seal problems a•er commis- sioning, leading South West Water to call in SPP Energy to investigate the situation. SPP Pumps are accredited as Certified Pump System Auditors (CPSA), and take the approach of discussing all operational issues in detail with the oper- ator onsite. Following thorough investigations, SPP got to the bottom of the issue: foreign material had entered the pumping sys- tem, in the form of rubber pellets used for cleaning small bore pipes in the foul tankers that collect wastewater from the septic tanks and discharge into the sew- age treatment works. These particles had travelled through the system and made their way into the pumps. SPP also investigated a long-standing cavitation problem which occurred when one pump ran solo. A full pump system assessment was completed - using ther- modynamic and ultrasonic test equip- ment. This identified that the station was originally designed for three pumps to run in parallel, generating sufficient dif- ferential head for the pumps to operate at their correct duty point. SPP Energy rec- ommended slowing the pumps down to MORE INFO ↖ 'Best Efficiency Point'. At this speed one pump running on its own did not cavitate. Overall, the benefits of carrying out the system assessment included an energy reduction totalling £105,000 cost savings per year; minimised whole-life costs of the system; reduced mainte- nance costs and downtime; increased system knowledge and control; and year- on-year savings verified by thermody- namic tests. Shayne Fielding, Efficiency Manager at South West Water, said: "Product reli- ability, energy reduction, reducing CO2 emissions and financial savings are all vitally important to us in helping to reduce our carbon footprint. This is why we work with SPP. Their team consist- ently goes out of their way to help us achieve our goals and its products and solutions add value to our business where it really matters."

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