A thermoeconomic analysis of an existing cogeneration plant

This paper compares and contrasts two thermodynamic process analysis techniques for a specific energy system. The first is the well known technique which utilizes the first law of thermodynamics to complete an energy balance for the system. The second technique utilizes the second law of thermodynamics to complete an exergy analysis on all of the components in the system.

An existing steam, electrical power generation system is the focus of this paper. The system is an industrial cogeneration system which exports steam at various pressure levels and electricity for use in the production facilities. The cogeneration plant provides dedicated service to three textile plants that are built on the same site. In addition to steam and electrical service, the cogeneration system provides chilled water, chilled brine and compressed air.

The analysis completed on this facility consists of amass balance, thermodynamics), an energy balance (first law (second law of thermodynamics) and a thermoeconomic analysis. This paper yields the benefits of each type of analysis, an appropriate method for costing the products of the facility, (steam and electricity) and recommendations to improve the performance of the facility.

The main findings of this analysis are: (1) The first law of thermodynamics analysis alone is insufficient to provide the information required to properly evaluate an energy system. The second law of thermodynamics is required. to complete a detailed analysis, and to produce meaningful results. (2) The steam generation equipment in the facility is extremely inefficient based on a second law efficiency. A number of economically-viable retrofits that would improve the overall exergetic efficiency of the cogeneration facility are presented.