ASSET MANAGEMENT
Replace pumps, cut repair bills
The original design of Progress Energy's Lee Plant in Goldsboro, N.C., enlisted nine vertical sump pumps within the plant yard as drain pumps. In this type of design (Figure 1), the motor is at the top of a shaft that extends down to the bottom of the sump, where the pump itself is located. At the Lee plant, the vertical pumps remove all kinds of water: standing accumulations of rainfall, coal pile runoff, and water from storm drains from equipment washdowns. The pumps' outputs are piped to a retention settlement basin whose sumps are below grade.
1. Problematic pumps. Vertical sump pumps played an important role at Progress Energy's Lee Plant: keeping the plant yard properly drained. But as they aged, the pumps became less reliable and more expensive to maintain. Gorman-Rupp horizontal self-priming centrifugal pumps were selected as a replacement. Courtesy: Gorman-Rupp
As the pumps aged, their maintenance became more frequent and more expensive. Several years ago, their reliability had deteriorated to the point of compromising overall plant operations. "We were rebuilding those nine vertical line sump pumps on a regular basis," said Ed Davis, a senior work management specialist with Progress Energy. Replacing the pumps became a matter of "when," rather than "if."
Opportunity knocks
About four years ago, Davis consulted Bill Lynch of Tencarva Machinery Co. (www.tencarva.com), an employee-owned firm that specializes in rotating equipment and wastewater pumps for industries such as power generation.
After further discussions with Lynch at the plant, Davis decided to replace the vertical line sump pumps by horizontal, self-priming, centrifugal pumps. In addition to being more efficient, the centrifugal pumps are easier to maintain because they can be installed above ground level at the top of the pumping station, with only a suction line submerged below grade.
Ultimately, Davis specified Gorman-Rupp's (www.gormanrupp.com) Super-T pumps in three sizes: 4, 6, and 8 inches. "When we compared the cost of the new pumps to the cost of maintaining the old ones, we felt the savings justified investing in new motor skids and controls as well," said Davis.
Before making a final decision to replace all nine vertical sump pumps, Progress bought two of the Gorman-Rupp centrifugal pumps on a trial basis and installed them over the course of 18 months. "To make sure we'd be making a sound investment, we wanted to spend time observing the pumps closely," Davis said. According to Tencarva's Lynch, it took teams of two or three men about two weeks to make the switch, including piping and electrical modifications.
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