(83a) Pinch and Exergy Analyses within Process Simulation Software to Enhance Process Energy Efficiency

P. Baudet¹, O. Baudouin¹, S. Déchelotte¹, Q. Duval¹, B. Wincure²

¹ ProSim SA, Immeuble Stratège A, 51 rue Ampère, F-31670 Labège, France

² ProSim, Inc., Science Center, 3711 Market Street, 8^th Floor, Philadelphia, PA 19104, USA

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 in particular in the process industries.

Pinch analysis [1] is a well-known methodology, commonly used in the industry to optimize process energy consumption. Specific developments have been done in a commercially-available process simulator, ProSimPlus^® Energy [2] to help process engineers in their daily work. Composite curves, characteristics of cold and hot streams of the process are automatically generated and an appropriate heat exchangers network is proposed by the software, depending on several constraints provided by user. Energy management specific unit operations (heat pumps, ORC, boilers…) were also added in the library of the software to help user to quickly analyse the impact on energy efficiency of such equipment. To tackle the challenge of process energy management enhancement, exergy analysis has been shown by Kotas [3] to be also 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 ProSimPlus^® Energy [3], [4]. The software combines these approaches, allowing user to propose the more efficient process taking into accounts all the defined constraints. Industrial examples of use of this tool will be presented to highlight main interest for process engineers.

REFERENCES

[1] Bodo Linnhoff, PhD thesis “Thermodynamic Analysis in the Design of Process Networks”, Leeds University, 1979

[2] www.prosim.net

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

[4] 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