Section 316(b) of the Clean Water Act requires plants with intake flows of over 2 million gallons of water per day taken from the waters of the United States to implement the “best available” technology to reduce injury and death of fish and other aquatic life that may be impinged on or entrained in the intake. The two options commonly identified to address 316(b) are closed cycle cooling and fish screens. A third option that is often overlooked and may be less expansive is to implement changes in the plant, allowing it to operate with less condenser circulating water (CCW) flow.

Most CCW systems of power plants were originally designed to achieve an economic optimum balance between capital cost and the operating benefit of a lower main condenser (MC) pressure with the resulting increased electrical output. For those plants that are located on rivers, lakes, and oceans where CCW was abundant and free, economics often dictated high CCW flows impelled by low-head pumps and MC’s designed with minimal surface areas, as larger MC’s were not justified on the basis of economics. The passage of Section 316(b) of the Clean Water Act suggests a new look at the existing CCW system design for many plants with the goal of reducing the required CCW flow rate. In some instances simply reducing the CCW flow rate may be sufficient to meet 316(b) requirements. In other cases, the reduction of CCW flow may significantly reduce the capital and operating cost of adding cooling towers and/or fish screens.

This paper investigates ways to reduce the required CCW flow to existing power plants by redesigning and modifying the existing CCW system based on current technology. The result could be a new, improved, MC and other turbine cycle equipment and perhaps new CCW pumps, resulting in the same or better plant performance. The paper presents case studies in which the CCW systems for two power plants are redesigned to reduce the CCW flow.

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