Automated retrofit design of cooling-water systems

An automated approach from the systematic investigation of interactions between cooling-tower performance and the cooling-water network design was developed for retrofit design of cooling-water systems. Introducing reuse of cooling water between different cooling duties enables cooling systems to be debottlenecked. The series arrangement of heat exchangers, however, results in a pressure drop increase because of the cooling water reuse. An optimization model for cooling-water networks developed considers pressure-drop constraints, complexity of networks, and efficient use of the cooling tower. A new node-superstructure model is suggested to consider the intensive property of pressure and the sequence of connections simultaneously. Physical insights are used to provide a good initialization for the resulting optimization problem. Issues of retrofit analysis are also addressed to give design guidelines for debottlenecking of cooling-water systems.