"Life-Time Oriented" Design and Operation of Energy Conversion Plants: Criteria and Procedures

The design, operation, control and diagnosis of energy conversion systems are different aspects of an integrated approach, which considers the whole life-time of the plants and brings about different skills: - applied thermodynamics and its various methods of analysis and assessment of functional performances; - machine design, stress analysis and mechanical control of components, to assess their health state and expected durability; - diagnosis methods, to check the departures from the expected performances and identify their causes; - economics, in both designing the plant and deciding if and when it is advisable to do maintenance or an overhaul on machines to restore them to expected performance. Different methods, procedures and techniques are discussed here, in order to select the most suitable approach to the “life time oriented” design and operation. The following base points have been identified and are presented in this paper: - to implement efficient operation models of the plants and employ suitable computer codes able to simulate the nameplate and off-design operation as well as to check the consistency of the data coming from the measurement systems; - to apply the traditional first-law analysis for preliminary thermodynamic calculations and on-line checks; - to use the exergetic and exergoeconomic analyses to obtain further and more valuable results, both in the design of the plants and during their operation as well as in the diagnosis of departures from the reference values of the parameters (due to malfunctions or change in boundary conditions). Some results coming from the application of these procedures to a cogenerative plant are shown.