(421d) Analysis of Chemical Process System Analysis with Entropy Generation

Systematic analyses of chemical process systems with the two steady-state balance equations from the First and Second Laws of Thermodynamics are used to provide insights about both energy efficiency and property models, using entropy generation as the indicator. Such evaluations of overall processes and of subsections provide reliable comparisons for energy requirements of process alternatives, indicate the impacts of potential changes, and check property model and calculational consistencies. Especially useful are the constraints that entropy generation must be positive for all sections, and that the sums of section values for heat rejection and entropy generation must equal those from an overall analysis. Examination has been made of three different post-combustion carbon-capture processes with the same flue-gas feed and products. Entropy generation allows comparison of their overall energy requirements, suggests outcomes for improving efficiency, indicates inefficiencies of process sectors, and reveals inconsistencies in absorption solvent property models for MEA and NH₃. Extensions to publications^1,2 will be shown.

References:

1. J.P. O’Connell, “Chemical process systems analysis using thermodynamic balance equations with entropy generation”, Comp. & Chem. Eng. 2017, 107, 3-15.
2. J.P. O’Connell, “Chemical process systems analysis using thermodynamic balance equations with entropy generation. Revaluation and extension”, Comp. & Chem. Eng. 2018, 111, 37-42.