Developing Sealless Integral Motor Pumps Using Axial Field, Permanent Magnet, Disk Motors

Abstract

Problems with mechanical shaft seals account for the majority of pump maintenance costs. When pumping critical or hazardous fluids, users can resort to sophisticated mechanical shaft sealing systems, complicated buffered double seals, or sealless pumps in either a magnetically coupled or canned motor configuration. User preference based on past experience usually determines which concept is selected. While seal manufactures have developed and marketed new seal configurations to meet the challenges of environmental regulations and seal reliability, sealless pump manufacturers have focused on component developments aimed at improving the reliability of existing designs. Now, an innovative sealless pump configuration is presented as an alternative to the traditional approaches used to seal pumped fluids from the environment. This configuration utilizes an axial field, permanent magnet motor integrated directly into the impeller structure and pump casing. This integration produces a configuration that has many mechanical advantages over conventionally designed sealless pumps and pumps using sophisticated mechanical seal packages. The sealless centrifugal axial-field motor pump (SCAMP) requires a polyphaser inverter (similar to a variable frequency drive), which offers additional operational benefits. A range of prototypes has been built and tested. Development of commercial applications in now in progress.