The Duke Energy Zimmer Generating Station located in Moscow Ohio is a 1400 Mw unit utilizing four pumps in ash handling water service. The pump’s suction source is the dewatering surge bin. The pumps discharge to both the bottom ash and pyrite jet pumps where the water is mixed with pyrites and bottom ash and subsequently conveyed to the bottom ash and pyrites dewatering systems.

All of the pumps experience rapid internal degradation over the years of operation primarily due to the suspended solids in the ash water. The result of the damage includes a significant decrease in hydraulic performance and increased vibration amplitudes with resultant short bearing and mechanical seal longevity.

This paper discusses the pump repairs and design changes performed to restore hydraulic and mechanical performance to provide an acceptable MTBR (Mean Time Between Repairs).

Contained in the paper are the details of the following:

• Assessment and analysis

○ Establish baseline performance on the existing pumps

○ Assess the as found pump condition

○ Evaluate potential hydraulic upgrades to the pump

○ Evaluate potential mechanical upgrades to the pump

• Implementation

○ Restoration of hydraulic passages

○ Implementing upgrades to the pump

○ Pump start-up and performance verification

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