Exergy aided pinch analysis to enhance energy integration towards environmental sustainability in a chlorine-caustic soda production process

Abstract

This paper presents a case study on the improvement of energy integration in a chlorine-caustic soda process based on the main sources of thermal exergy losses. Exergy analysis has been performed to pinpoint the causes of thermal exergetic inefficiency. Thermal solutions have been then developed, leading to a comprehensive list of cold and hot process streams. Finally, pinch analysis has been brought into action to estimate the minimum energy requirement, to select utilities and to design heat exchanger network. As a result, the combined methodology followed here takes advantages of both exergy and pinch analyses. This bilateral thermal-exergy-based pinch approach helps to set energy targets in a way that all the possible thermal solutions supported by exergy analysis are considered, including all hot and cold process streams that have a high potential for heat integration during pinch analysis. To demonstrate this, energy targeting through conventional pinch analysis leads to 7.74MW and 13.00MW of hot and cold utility energy demand, respectively. These figures change to 8.17MW and 0.40MW of hot and cold utility energy demand, respectively through streams screening by the combined methodology.