A Very High Head Pump

Preliminary process design in 1997 for a new grass roots polymer unit in the Gulf Coast raised the possibility of using a single centrifugal pump instead of two reciprocating compressors to feed ethylene into the reactors. The objectives of this change were lower capital cost, energy consumption, and maintenance expense. Discussion of the possible application led finally to the design, manufacture, and successful operation of two full-capacity horizontal centrifugal pumps, one operating, the other on autostart standby, each developing 22,500 ft (6860 m) in a single casing. This paper addresses the design philosophy chosen for these pumps, critical steps in their detail design, manufacturing issues, additional testing on water to verify the design to the extent possible before operation on ethylene, and the correction of fluctuating rotor instability evident in one of the pumps at startup in July 2000.