Advanced energetics of a Multiple Effects Evaporation (MEE) desalination plant Part I: 2nd principle analysis by a zooming representation at single-effect level

Abstract

This paper represents the Part I of a paper in two parts, aimed at proposing a 2nd principle and thermoeconomic analysis for a Multiple Effects Evaporation (MEE) process and discussing solutions for optimization and energy saving. After a brief analysis of the thermochemical fundamentals of desalination, the minimum theoretical work of separation is introduced to represent a reference condition for the assessment of plants' efficiency. A forward feed MEE configuration is then analysed, abandoning the conventional approach to “at overall plant-level”-analysis; a zooming strategy, based on focusing on the physical model of a generic stage (i.e. effect), is preferred to best recognize the margins for systems' improvement. The energy conversion process taking place in the examined effect reveals very inefficient and the specific contribute of any subprocess to the overall exergy destruction is evaluated. In the Part II of this paper, it will be seen that the cost formation process enables us to perform more accurate optimizations; also, a realistic approach to energy saving by cost integration will be outlined.