PUMP EFFICIENCY
All of this is done without the need for additional external sequencers and associated wiring. There has always been the question of when is it best to run with one pump, or two pumps in parallel and I will explain how we can overcome this.
As the first pump is ramping up, just prior to when it stages in a second pump, it records the power consumption pre and post staging. If the recording after staging shows the power consumption has increased, it means the setting was incorrect and it was better to run longer with one pump. The drive system records this and automatically adjusts it stage setting so the next time it stages it does so at the most efficient point. This is constantly monitored and automatically adjusted every time a staging of pump takes place. This means that not only will the system offer the highest efficiency, but as the pumps begin to wear across their lifetime and the best efficiency point (BEP) changes, the drive system will automatically react to ensure we maintain the highest efficiency possible.
Impeller deragging
Ragging of wastewater pump impellers is a serious ongoing issue. Traditionally it reduces pump efficiency and can cause pump blockage resulting in major downtime to lift the pump out of service to carry out the required maintenance. New technology now has dedicated de-ragging software features within the drive. This optimises the
efficiency of the pump by constantly monitoring the motor shaft power consumption, relative to flow, and reacts with a reverse spinning cleaning cycle when a deviation from the power consumption of the system design is recorded. This intelligent system is fully flexible and can be optimised to meet the individual needs of applications. During the commissioning sequence, the user can determine when the system should react – at start command, stop command, during running, by digital input or time based. A combination of any of these events is possible to ensure the highest pump efficiency is maintained and ragging of the impeller is minimised. The user can also define how many times the drive should spin the impeller in reverse, at what speed and for how long. The LCP display of the drive shows a clear indication of the status of the deragging function. Please be aware that not every pump can be run in reverse and the operator should always check with the pump manufacturer before specifying this type of control. Modern day drives technology not only offers the possibility to reduce lifecycle costs, but now, with dedicated software features, can also reduce the level of initial costs by eliminating the need for costly external devices traditionally used to give the required control or protection in a pumping system. nnn
This paper was presented at The Pump Centre Conference in Runcorn in May
Pumps slash blockages and energy use
In March, Anglian Water called on ABS Wastewater Technology to investigate a problem pump station site, Rampton High Street, where there were issues with high wet wells and flooding. The existing pumps were blocking regularly and not keeping up with incoming flow especially during storm conditions. This was causing over 20 callouts per year and leading to customer complaints concerning flooding of the surrounding area and extra costs to cover tankering.
ABS engineers carried out an
energy survey of the station to determine the existing performance of the pumps and calculate a duty point that would maintain the incoming flow even during storm conditions, whilst not increasing the power consumption of the pumps. This showed that the existing pumps were performing inefficiently, had wear on the hydraulics and that the pedestal were both worn and leaking.
With the energy survey complete, a new pump
ABS EffeX: reduced call outs
selection was made from the ABS EffeX XFP range which best suited the requirements of the pump station and could deal with the rag in the wet well. New ABS pedestals and guiderails were installed to prevent leaking from the seals and the new pumps were then installed and tested to confirm the calculated duty point. It was found that the energy consumption of the pump station had been reduced by 46%, which means the saving in energy will pay for cost of the pumps in under five years. Run times have also been reduced by over an hour per day and there have been no call outs due to blockages since the pumps were installed. John Usher, Anglian Water’s asset maintenance performance manager, confirmed the improvements seen: “Prior to the new ABS EffeX pumps being installed this site had numerous call outs. Since the new ABS pumps have been installed we have had 10 months of vastly improved reliability. The energy used by this site has also been reduced by half.” nnn
There’s nothing in the air!
Dependable odour control systems designed for
cost
effective operation
01403 221000 info@ergapc
co.uk
June 2011 Water & Wastewater Treatment 17
www.ergapc.co.uk
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