Exergy analysis of purified water plant in a pharmaceutical industry

Abstract

Thermodynamic optimisation of manufacturing plants at design or operation stages is known to be a complex process, resulting from the consideration of various design and operation parameters. Exergy analysis is an appropriate tool to implement the thermo-economical optimisation of processes in a convenient way. In this study, exergy analysis was applied to a purified water (PW) plant in the pharmaceutical industry composed of various units such as ultrafiltration (UF), activated carbon columns, softener columns, reverse osmosis (RO), degasser, and continuous electro deionisation unit (CEDI) process, and the exergetic efficiencies were found to be 75.47%, 84.70%, 64.78%, 37.67%, 96.88% and 85.50%, respectively. Considering the exergetic efficiency of the entire plant of 4.35%, significant opportunities are available to increase the energy and exergy efficiencies of this PW plant by means of structural as well as parametric optimisation tasks. By considering that most of the energy destruction in this plant stems from pump motors, especially in the RO unit, energy recovery devices such as pressure ex-changers and Pelton wheels may be used to increase the energy efficiency of the plant.