Chemical process systems analysis using thermodynamic balance equations with entropy generation

Abstract

Systematic analyses of chemical process systems with steady-state balance equations for Material, Energy and Entropy can yield insights about energy efficiency and property model consistency, with entropy generation being the indicator quantity. Calculations of different sets of independent overall and subsection variables can reveal inefficient locations as well as the impacts of changes in process configuration and conditions. Demonstration is also made of how the analysis tests properties models because values of entropy generation must be positive, and the sum of heat rejections and entropy generations from sections must equal those from an overall analysis. Examples focus on chemical processes with internal circulation of complex mixtures, including thermochemical decomposition of water, and three different carbon-capture processes having essentially the same flue gas feed and gaseous products. Ranking of the CO2 capture processes is made, while negative entropy generation is encountered with some property models.