Performance Of Combined Cycle Power Plant Research Articles

Degradation Effects on Combined Cycle Power Plant Performance—Part I: Gas Turbine Cycle Component Degradation Effects

This paper describes the effects of degradation of the main gas path components of the gas turbine topping cycle on the combined cycle gas turbine (CCGT) plant performance. First, the component degradation effects on the gas turbine performance as an independent unit are examined. It is then shown how this degradation is reflected on a steam turbine plant of the CCGT and on the complete combined cycle plant. TURBOMATCH, the gas turbine performance code of Cranfield University, was used to predict the effects of degraded gas path components of the gas turbine have on its performance as a whole plant. To simulate the steam (bottoming) cycle, another Fortran code was developed. Both codes were used together to form a complete software system that can predict the CCGT plant design point, off-design, and deteriorated (due to component degradation) performances. The results show that the overall output is very sensitive to many types of degradation, especially in the turbine of the gas turbine. Also shown is the effect on gas turbine exhaust conditions and how this affects the steam cycle.

Degradation Effects on Combined Cycle Power Plant Performance—Part II: Steam Turbine Cycle Component Degradation Effects

This is the second paper exploring the effects of the degradation of different components on combined cycle gas turbine (CCGT) plant performance. This paper investigates the effects of degraded steam path components of steam turbine (bottoming) cycle have on CCGT power plant performance. Areas looked at were, steam turbine fouling, steam turbine erosion, heat recovery steam generator degradation (scaling and/or ashes deposition), and condenser degradation. The effect of gas turbine back-pressure on plant performance due to HRSG degradation is also discussed. A general simulation FORTRAN code was developed for the purpose of this study. This program can calculate the CCGT plant design point performance, off-design plant performance, and plant deterioration performance. The results obtained are presented in a graphical form and discussed.

Modeling of heat recovery steam generator performance

The performance of the heat recovery steam generator (HRSG) strongly affects the overall performance of a combined-cycle power plant. An accurate simulation of the performance of the HRSG is therefore necessary to analyze the effects of various design and operating parameters on the performance of combined-cycle power plants. Unfortunately, there are many sources of uncertainty and operational variance which prevent the accurate prediction of the HRSG performance. Furthermore, the prediction of heat-exchanger performance is based on assumptions about flow patterns. Empirical correction for departures from these assumptions is not possible in cases where the benefits of new geometrical configurations are to be explored. A numerical method was developed to predict the performance of the HRSG in a fashion that accounts, as much as possible, for the design and operation constraints, while keeping computational complexity manageable. The method is intended for use in performance-simulation models of advanced power cycles, since its accuracy is acceptable without requiring large computational resources. The method was used to simulate the pressure, temperature, steam quality and heat-flux distributions in a commercially available HRSG (operating under full- and part-load conditions). The predicted results were found to compare well with measurements obtained on full-scale units.

Probabilistic outage analysis of a combined-cycle power plant

Using the classical method of fault tree analysis, various reliability, availability and maintainability related characteristics of a package-engineered gas-fuelled combined-cycle power plant, comprising a GUD 2.94.3 block, were determined. The events of interest-top events of fault trees-are the power plant's losses in net power output due to forced outages. Additionally, exemplary losses due to scheduled outages were taken into account. The numerical findings of this RAM analysis reflect the high RAM performance of combined-cycle power plants.