Efficient utilization of electrical energy in pumping operations based on existing conditions - A case study

The intersection of the pump characteristics with the system characteristics gives the design operating point for a given pumping system. Changes in conditions of fluid viscosity, total head, throttle positions, supply system parameters etc causes the operating point to shift on either side of the pump head-discharge curve, which affects not only the hydraulic output of the pump, but also results in the inefficient utilization of available electrical power. Use of variable speed drives involves additional investment, which if the pump is in operation for long hours every day throughout the year with the number of such units in operation being small in number, but is the best possible option to achieve energy efficiency. But if the industrial utility has large number of pump units for various processes, with individual operating times being quite insignificant, yet important in the process involved, variable speed drives may not be the best possible solution. This paper makes an attempt in presenting a simple method for making the pump to work at / or near its operating point based on the exiting system conditions, with the least possible changes to the working setup in addition to achieving the desired objective of efficient utilization of the available electrical power. The analysis is supported by a case study.