Concept on thermoeconomic evaluation of steam turbines

Concepts of exergoeconomic audits and evaluation of steam turbines are presented. In the first part of the work, an analysis based on the first and second laws of thermodynamics is applied to a power plant. The well-known procedures of “Exergy Cost Theory” and the “General Theory of Thermoeconomics” proposed by Valero et al. [V. Verda, L. Serra, A. Valero, Zooming procedure for the thermoeconomics diagnosis of highly complex energy systems, Int. J. Appl. Thermodyn. 6 (2) (2002) 75–83] are used. These methodologies allow the computation of exergy-cost and economic-cost of local products (P) and fuels (F) in each plant component (especially in steam turbines). The second part of the work consists of an evaluation and determination of the degree of entropy generation (ΔSg) and power loss (ΔW) in a steam turbine stage (nozzle-bucket), under the detection of specific malfunctions. As it is well known, steam turbines can develop intrinsic malfunctions such as roughness, seal and leak clearances, erosion, and sedimentation. The main objective of this work is to assess the exergy-cost (fuel impact cost) due to the intrinsic malfunctions in a steam turbine stage.