An Integrated Cooling Water Intake System Enhancement Strategy

Cooling water intake problems come in many forms. These problems can include large schools of fish or jellyfish, seaweed, lake grass, sand, and silt buildup or carryover in the cooling water intake and screen house. Lower lake levels and higher average temperatures, zebra mussel infestation, and non-uniform flow rates between traveling water screen (TWS) bays and circulating water pump bays due to under-sized intake structures can also affect cooling water intake. Downstream of the cooling water intake, flow imbalances caused by entrained debris challenge heat exchanger designs and aging equipment. One Midwestern plant developed an integrated approach to improve the overall performance of the cooling water intake which will result in increased operating efficiency. For the subject plant, this paper will discuss specific modifications planned or undertaken and their benefits and limitations, flow modeling and design margin analyses completed and in process, anticipated reduction in debris carryover, impingement, and entrainment, and suggested further improvements. The majority of modifications undertaken or planned at the subject plant are generally intended to minimize debris carryover and to reduce problems associated with system blockages and heat exchanger tube fouling. Specific modifications to be discussed include: an acoustic fish deterrent system at the inlet tunnel entrance, replacement of the flow-through TWS’s with an industry first-of-a-kind design screen technology, screen wash, and debris transport and removal system modifications, service water system strainer basket modifications, service water system heat exchanger repairs and modifications, and installation of a sodium hypochlorite system.