Fontina Petrakopoulou

Assessment of a Power Plant With CO2 Capture Using an Advanced Exergoenvironmental Analysis

This paper presents an evaluation of the environmental performance of an advanced zero emission plant (AZEP) including CO2 capture. The evaluation is conducted with the aid of an advanced exergoenvironmental analysis. The results are compared with those of a reference combined-cycle power plant without CO2 capture. Advanced exergy-based methods are used to (a) quantify the potential for improving individual components or overall systems, and (b) reveal detailed interactions among components—two features not present in conventional analyses, but very useful, particularly when evaluating complex systems. In an advanced exergoenvironmental analysis, the environmental impacts calculated in a conventional exergoenvironmental analysis are split into avoidable/unavoidable (to evaluate the potential for component improvement) and endogenous/exogenous (to understand the interactions among components) parts. As in the reference plant, the potential for reducing the environmental impact of the AZEP has been found to be limited by the relatively low avoidable environmental impact associated with the thermodynamic inefficiencies of several of its components. However, although the environmental impacts for the majority of the components of the plant are related mainly to internal inefficiencies and component interactions are of secondary importance, there are strong interactions between the reactor and some other components.

Steam generator design for solar towers using solar salt as heat transfer fluid

Since the operation of a concentrating solar power plant depends on the intermittent character of solar energy, the steam generator is subject to daily start-ups, stops and load variations. Faster start-up and load changes increase the plant flexibility and the daily energy production. However, it involves high thermal stresses on thick-walled components. Continuous operational conditions may eventually lead to a material failure. For these reasons, it is important to evaluate the transient behavior of the proposed designs in order to assure the reliability. The aim of this work is to analyze different steam generator designs for solar power tower plants using molten salt as heat transfer fluid. A conceptual steam generator design is proposed and associated heat transfer areas and steam drum size are calculated. Then, dynamic models for the main parts of the steam generator are developed to represent its transient performance. A temperature change rate that ensures safe hot start-up conditions is studied ...