An Analysis of Motor System Optimization Options- A Question of Diminishing Return on Investment

Abstract

This paper presents the verified results of a pump system optimization project at a major midwestern brewery. A 150-horsepower "sweet water" pump circulates a glycol/water solution to cool tanks of beer during fermentation. To keep the pump from overloading the motor, the discharge throttling valve was kept mostly closed, reducing flow and increasing pressure drop. The result was inadequate cooling and energy waste. A systems analysis showed that trimming the impeller would cut the required pumping energy by more than half. The impeller was trimmed and the energy savings paid for the entire project including the systems analysis in only six months. Further optimization efforts are currently under way on this system.