Water conservation through energy management

The objective of this paper is the simultaneous management of two important industrial resources – energy and water. A class of industrial processes where heat transfer is accompanied by mass transfer (water evaporation and condensation) are concerned, and special attention is given to them where the transfer of heat is a limiting stage. These processes are considered not in isolation but in integration with all related processes and subsystems. More specifically, the set of processes and subsystems include cooling systems, systems of contact economizers for flue gas energy recovery, scrubbers, direct steam heaters, driers, related systems of coolers and the heat exchanger networks. The proposed preliminary design procedure is based on concepts and tools related to Pinch technology especially modified for consideration of simultaneous heat and mass transfer. The manipulated parameters include process' latent and sensible heat loads and systems' structural changes with efficiency criteria allowing sacrifice of quantity for quality of performance. Two specific procedures allow targeting of maximum flue gas energy recovery and minimum temperature of cooling water providing guidance to structural design and system operation. The application of the proposed methodology is designed to achieve water conservation through minimization of water evaporation losses. Its significance is demonstrated through three popular industrial applications (a power station, a brewery and a tissue factory).