(203x) Exergy Analysis Within Process Simulation Software to Enhance Process Energy Management

Industrial sectors account for one third of global energy consumption. A common feature of industrial processes is reliance on fossil fuels as the primary source of energy, where a large part of the energy consumption is spent on production of utilities (electricity, steam at various pressure levels, hot/cold water, hot flue gas…). As this reliance on fossil fuels has huge negative impacts on the environment, the scientific world makes a significant effort to find alternative sources of energy. However, even by the most optimistic assessments, these alternatives are long-term solutions and many projections show that in the near future, fossil fuels will remain as the primary sources of energy.

To tackle this challenge, exergy analysis has been shown by Kotas [1] to be a useful tool that exploits the concept of energy quality to quantify the portion of energy that can be practically recovered. Unfortunately, in contrast to enthalpy, this concept is less familiar to chemical engineers and can be rather difficult to handle. In particular, this physical quantity is rarely implemented in process simulators. To make exergy analysis more understandable and to demonstrate its value for the analysis of the energy efficiency of a process and its utilities, a fully-automated exergy analysis tool has been developed and integrated in a commercially-available process simulator, ProSimPlus^® [2], [3]. Starting from basic exergy concepts, the exergy calculation methodologies for material, heat and work streams as well as their implementation in ProSimPlus^® will be presented. To provide the essential elements for exergy analysis, exergy balance and the most commonly used exergy efficiencies will also be presented.

REFERENCES

[1] Kotas T. J., “The exergy method of thermal plant analysis”. Butterworths (1985)

[2] www.prosim.net

[3] Ghannadzadeh A., Thery-Hetreux R., Baudouin O., Baudet P., Floquet P., Joulia X., “General methodology for exergy balance in ProSimPlus^® process simulator”, Energy 44 (2012), 38-59