VSDs slash pump energy consumption for aquarium - The installation of ABB variable-speed drives to control pumps at the National Marine Aquarium in Plymouth is reducing electricity bills by over £15 000 a year. A saving of £2900 a year is being achieved with one 11 kW pump alone.      Nine variable-speed drives have replaced programmable logic controllers and control of flow and pressure by manual throttle valves — resulting in excessive energy consumption as the pumps always ran at full speed.The new installation uses pressure transducers in the pump output to provide a feedback signal to the drive to vary speed to provide the desired flow rate.Duty and standby pump sets are controlled by a single drive, changing over automatically as required.          The aquarium has a seawater tank holding 2.5 Ml. Keeping the fish healthy involves constant pumping of water at the correct temperature. John Selwood, engineering manager for the aquarium, says, ‘We needed to save energy. However, we have nine pumps for the tanks that must be on all the time, with varying flow and pressure.’                                                                                                 The requirement for constant operation meant that the installation of the drives had to be achieved with minimum downtime. Andrew Botterill, managing director of electrical contractor Drew & Co., explains, ‘We programmed one drive and tested it in the workshop. Then all we had to do was to plug that drive’s keypad to the other drives and upload the parameters. The interchangeability of the keypads was the key to installing the drives quickly. We installed each drive in only two hours.’

Energy Savings by reducing the size of an Impeller - Salt Union Ltd produces white salt by the muitistage evaporation of brine. Operational analysis showed that the pressure generated by the condensate export pump was considerably higher than was necessary. The high degree of throttling that was consequently needed had led to instability in the system, resulting in mal-operation and high maintenance costs. After discussion with the pump manufacturer, Salt Union decided to trim the diameter of the pump impeller. This eliminated the instability and resulted in significant energy savings. Reducing the power required by the pump also allowed a smaller motor to be fitted, which produced further energy savings. Delivered Energy savings: 710 GJIyear, worth £8,900/year Savings in repair and maintenance costs: £3,000/year Overall total savings: f 11,900/year The payback on the impeller trim was achieved in eight days. Click here to download this file

High Efficiency Motors on fans and pumps - At Deita Extrusion five motors were replaced with higher efficiency motors to give a reasonable cross section of the range of cast iron motor ratings. Three of the motors were running continuously; the remaining two ran on a 5-day, 3 shift operational pattern. Measurements of average load and data on motor efficiency were used to compare the running costs of the new higher efficiency motors with the equivalent standard motor. A comparison was also made with the running costs of the motors which had originally been installed. Delivered Energy Savings 11.66 MWh/year (42 GJ/year), worth £408/year Payback Period 1.64 years. Click here to download this file

Variable speed drives in a chemical plant - At Cray Valley as part of the production process, chemicals are stirred inside batch reaction vessels where the speed of stirring is critical. The established method of speed control was a fixed speed motor driving a variable volume hydraulic pump. However, because VSDs have become more cost effective in recent years, Cray Valley has been replacing these hydraulic drives with VSDs. This project has demonstrated that VSDs Can provide significant cost savings. In this study examples are given of the replacement of two cooling water pump installations and a stirrer application. Delivered Energy Savings of 1,300 GJ/year, worth £15,800. Payback Period 1.9 years, Building 27 water pump, 1.4 years, Building 2 water pump, 2.4 years, Stirrer motor Click here to download this file

If you have any Case Studies that you would like to publish on this site please contact us.