Use of Computation Fluid Dynamic Modeling to Evaluate Pump Intake Performance and Develop Design Modifications

Abstract

The generating capacity of a power plant is being increased through the addition of another power block at the facility. The plant utilizes a once through cooling system with a large onsite pond for water storage. The new power block will require additional pumping capacity. A large intake structure containing eight 6.31 m 3 /s circulating water pump in separate bays is located on the pond. One proposed approach for supplying cooling water to the new power block was through the addition of six 3.15 m 3 /s pumps within the existing intake bays. This approach would reduce the construction schedule and the project cost. A commercial computation fluid dynamic (CFD) model was used to investigate the pump approach hydraulics, and evaluate the likelihood of traditional design modifications to improve the flow conditions approaching the pump intakes. Traditionally, physical hydraulic models have been used to evaluate pump intake design modifications. A CFD model was used for this study because it could demonstrate the feasibility of the project more quickly and at a lower cost than it would take for performing a physical model study. Results from the CFD model demonstrated that traditional intake design modifications could improve the intake hydraulics. Background A new generating unit is being added to an existing power plant. The current facility utilizes a once-through cooling system with a large onsite cooling pond for water storage. The effective pond length has been increased by levees constructed to channel flow thereby increasing the residence time between the outfall and intakes. A concrete intake structure is located at the end of a canal created by one of the levees in the pond. The intake structure is divided into eight pump bays that are 5.18 meters wide by 20.9 meters long. Each bay contains a 6.31 m 3 /s circulating water pump. Some of the bays also contain much lower flow screen wash pumps and auxiliary water supply pumps. The peak intake flow is approximately 54 m 3 /s. The new generating unit will require an additional 18.9 m 3 /s of cooling water. One alternative for supplying the additional cooling water is to increase the flow capacity of the exiting intake. This would be accomplished by adding six additional circulating