At the Greater Cincinnati Water Works (GCWW), energy management is an important
component of operating all pumping facilities. During a recent energy management
analyses of a 35 mgd pump station, it was determined that significant energy savings
could be achieved if the pumping operation was radically changed. The normal operation
of the facility was a "dump and pump" operation, where the water from the upstream
distribution system fills the reservoir, and then the water is pumped from the reservoir to
the next pressure zone. Because the inlet pressures to the reservoir were significantly
higher than anticipated (70 psi versus 20 psi), an innovative solution was developed to
convert the pump station from a "dump and pump" operation to a booster pump
operation. Extensive hydraulic and economic analyses were performed to determine if the
existing pumps could be modified to efficiently operate as booster pumps, thereby
lowering the required horsepower usage and capturing significant energy savings.
However, the pump's ability to also operate as a lift pump had to be maintained to
continue using part of the 2.5 MG storage reservoir for water quality purposes. The
hydraulic analyses showed that by carefully trimming the pump impellers, the pumps
could be converted to pump efficiently in both the booster mode and the lift mode. The
economic analysis showed that the cost of modifying the existing pumps could be
recovered with the projected energy savings in less than three years. The long-term
electrical savings were estimated at about 20 percent of the current electrical costs. Also,
the 70-psi inlet pressure had to be reduced to about 10 psi before entering the reservoir.
Throttling the water into the reservoir was causing premature failure of a critical inlet
valve and resulted in undesirable pressure fluctuations on the upstream distribution
system. In conjunction with the pump modifications, the control valve to the reservoir
inlet was replaced with a unique valve called a sleeve valve. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 640 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 8 |
| Published : | 06/17/2005 |
