PROCESS INTEGRATION TECHNIQUES FOR OPTIMIZING SEAWATER COOLING SYSTEMS

This work addresses the problem of using seawater for cooling and the associated environmental problems caused by the usage and discharge of biocides. The discharged biocide and its byproducts are toxic to aquatic lives and must be decreased below certain limits on load prior to discharge. The conventional approach has been to add biocide removal units as an end-of-pipe treatment. This work introduces an integrated approach to reducing biocide discharge throughout coordinated strategies for in-plant modifications and biocide removal. Process integration tools are used to reduce heating and cooling requirements through the synthesis of a heat-exchange network. Heat integration among process of hot and cold streams is pursued to an economic extent by reconciling cost reduction in utilities versus any additional capital investment of the heat exchangers. Other strategies include maximization of the temperature range for seawater through the process and optimization of biocide dosage. This new approach has the advantage of providing cost savings while reducing the usage and discharge of biocides. Usefulness of this approach is illustrated on a case study.