Practical Approach to Exergy and Thermoeconomic Analyses of Industrial Processes

Abstract

The aim of this book is to enable the reader to perform the necessary calculations for an exergetic analysis (thermodynamics) and a thermoeconomic analysis (process costs) of any industrial process. Using the presented methodology, a deeper understanding and analysis of an example process will be obtained throughout the book. This process is an innovative working cycle that uses the exhaust gases from the gas turbine coupled with the compressor of a natural gas compression station. This kind of station is used in natural gas pipelines to recover the pressure needed by the gas to flow. The chosen cycle is an ammonia–water cycle. Throughout this book, all the concepts and calculations needed are broken down using the thermodynamic data obtained from an Aspen Plus simulation. The use of a simulation is greatly beneficial because it makes available the thermodynamic data needed for the calculation of the exergy of the process streams. Hand-made calculations for obtaining thermodynamic data are also explained, although the procedure can be difficult, since the following data are needed for each matter stream: • composition • mass flow • pressure • temperature • enthalpy increment between two states • entropy increment between two states • chemical exergy of the substances, or their free energy of formation • kinetic and potential energy if their variation is important in the process Also, the work values are needed, as well as the heat flows’ value and the temperature at which they are produced. All the calculations of the example used are done in a spreadsheet. Matrix algebra is continuously used to release calculations from the size and complexity of any facility. Valuable and additional material is available on a web page hosted by Springer http://www.springer.com/978-1-4471-4621-6. T