Optimum Turbine Extraction Pressures for Maximum Efficiency in Steam Power Plant Cycle

In design of a real steam power plant cycle with seven or eight open and closed feed water heaters, choosing the appropriate turbine extraction pressures has important effect on the cycle efficiency. By considering the steam cycle thermal efficiency as an objective function, various optimization techniques including the Full Search, Hook-Jeeves and Nelder-Mead schemes were applied for selecting the proper arrangement of feed water heaters and the optimum steam turbine extraction pressures. In order to optimally design and accurately analyze the behavior of steam power plant cycles, a modular software based on object oriented programming has been developed. Steam cycle elements used in this software while forming a set of independent objects, collectively present an inter-related behavior. In the design environment of the software, a complete steam cycle power plant can be visually designed and analyzed. The correct performance of this software in calculation of the state variations at various cycle points and the cycle thermal efficiency was checked and verified. The values of extraction pressures and mass flow rates at the optimum design point were assessed and found to be in agreement with the corresponding values of existing power plants. Based on the literature available, incorporation of all the design features involving modular aspect with optimization search using several algorithms and comparisons made of the results with actual power plant performances have not yet been successfully accomplished in a software package.