Methods and Tools for Analysis and Optimization of Power Plants

Sammanfattning: Modern societies' functionality is strongly dependent on the electricity. Efficient, environment friendly, and economical power production has been in focus for a long time. The introduction of computers and thereby computer-aided tools for pre-design studies, optimization and choice of the best operational strategies, has changed the conditions for power production tremendously. The most noticeable advantage of the introduction of the computer-aided tools in the field of power generation, has been the ability to study the plant’s performance prior to the construction phase. The results of these studies have made it possible to change and adjust the plant layout to match the pre-defined requirements. Further development of computers in recent years has opened up for implementation of new features in the existing tools and also for the development of new tools for specific applications, like thermodynamic and economic optimization, prediction of the remaining component life time, and fault diagnostics, resulting in improvement of the plant’s performance, availability and reliability. The most common tools for pre-design studies are heat and mass balance programs. Further thermodynamic and economic optimization of plant layouts, generated by the heat and mass balance programs, can be accomplished by using pinch programs, exergy analysis and thermoeconomics. Surveillance and fault diagnostics of existing systems can be performed by using tools like condition monitoring systems and artificial neural networks. The increased number of tools and their various construction and application areas make the choice of the most adequate tool for a certain application difficult. In this thesis the development of different categories of tools and techniques, and their application area are reviewed and presented. Case studies on both existing and theoretical power plant layouts have been performed using different commercially available tools to illuminate their advantages and shortcomings. The development of power plant technology and the requirements for new tools and measurement systems have been briefly reviewed. This thesis contains also programming techniques and calculation methods concerning part-load calculations using local linearization, which has been implemented in an in-house heat and mass balance program developed by the author. Results of calculations performed by the in-house program have been compared with results from commercial programs. The comparison shows good consistency [1, 2]. Methods suggested by the author increase the numerical stability, reduce the calculation time, and improve the user-friendliness by facilitating free choice of input data.