Demonstration Of Cavitation Life Extension For Suction-Stage Impellers In High Energy Pumps

Lecturepg. 103Cavitation occurring in high-energy pump impellers often results in material erosion and system instabilities. Excessive erosion rates compromise life and increase ownership costs through higher maintenance and reduced availability. Instabilities in the pumping system resulting from the presence of unsteady volumes of vapor resulting pressure pulsations and unsteady flow delivery. This behavior is a legacy of the increase in pump size and energy level that were required to support larger and more critical processes. The increased requirements resulted in “scaled-up” impeller designs that were not suited to deal with the resulting cavitation behavior. During the late 1980s to 1990s numerous development efforts were undertaken to correct these design issues. There has been little follow-up of these efforts so that the degree of success is largely undocumented. This paper revisits two such redesign efforts for boiler feed pumps that presented two separate challenges. Significant increases in cavitation life are documented by using design approaches developed during the early 1990s. Also considered is the growing use of computational fluid dynamics for predicting cavitating behavior of critical suction impellers