Monitoring of the thermoeconomic performance in an actual combined cycle power plant bottoming cycle

This paper presents a research project carried out by TPG (Thermochemical Power Group) of University of Genoa to develop innovative monitoring and diagnostics procedures and software tools for software-aided maintenance and customer support. This work is concerned with preliminary outcomes regarding the thermoeconomic monitoring of the bottoming cycle of a combined cycle power plant, using real historical data. The software is able to calculate functional exergy flows (y), their related costs (c) (using the plant functional diagram); after that non dimensional parameters for the characteristic exergonomic indexes (Δc, Δc*, Δk*) are determined.Through a plant optimization (not described here) the reference conditions of the plant at each operating condition can be determined. Then, non dimensional indexes related to each thermoeconomic parameter are defined, in order to depict a “cost degradation”, and thus a significant rise in the production cost of the main products of the bottoming cycle (steam and power).The methodology developed has been successfully applied to historical logged data of an existing 400 MW power plant, showing the capabilities in estimating the “cost degradation” of the elements of the BC over the plant life, and trends in the thermoeconomic indexes.