A Small Gas Turbine Plant for Cogeneration of Electricity, Thermal and Cooling Thermal Energy With an Absorption Unit

Abstract

A cogeneration plant with a small gas turbine was installed in a pharmaceutical factory and instrumented for acquiring all the values necessary to appraise both its energetic and cost advantages. The plant was designed and built as a demonstrative project under a program for energy use improvement in industry, partially financed by the European Union. The system comprises as its main components: 1) a gas turbine cogeneration plant for production of power and thermal energy under the form of hot water, superheated water, and steam; 2) a two-stage absorption unit, fueled by the steam produced in the cogeneration plant, for production of cooling thermal energy. The plant was provided with an automatized control system for the acquisition of plant operating parameters. The large amount of data thus provided made it possible to compare the new plant, under actual operating conditions, with the previously existing cooling power station with compression units, and with a traditional power plant. This comparative analysis was based on measurements of the plant operating parameters over nine months, and made it possible to compare actual plant performance with that expected and ISO values. The analysis results reveal that gas turbine performance is greatly affected by part-load as well as ambient temperature conditions. Two-stage absorber performance, moreover, turned out to decrease sharply and more than expected in off-design operating conditions.

Thermoeconomic Analysis and Optimization of a Gas Turbine Plant Combined With an Absorption Unit

“…This decline in energy could be reduced by using a two level pressure boiler. This choice cannot be economically justified, however, considering that the boiler exergetic performance (50.3%) is much higher than that of the remaining components: its cost share is Lucia et al, 1997). Component 4 (absorber + auxiliary boiler) in this period has an extremely low efficiency value: 20.3%.…”

“…The plant, described in detail by De Lucia et al (1997), is located in a pharmaceutical factory near Frosinone in Central Italy. It was initially composed of five compression cooling units and two boilers.…”