Study of Optimizing a Combined Cycle of Two Pressure Levels

Abstract

The topic of the thesis consists of a case calculation of power plants. The objective is to optimize combined cycle HRSG (Heat Recovery Steam Generator) pressure levels (two system pressures) for optimal efficiency. The objective of HRSG is to gain the maximum enthalpy difference at the same time as achieving a reasonable economic cost. If we want to get heat transfer by convection it is necessary to have gases with a higher temperature than the steam in any stage in order to be closer to the pinch points. To develop the case, an example of a power plant formed by combined cycle of two pressure systems has been created. Consequently, the system has been analyzed and studied in order to find the possible combinations for two pressure values which is the most optimal in order to enhance its performance. The mathematical simulation has been done with Excel with the corresponding enthalpy functions in order to determinate the function for the maximum efficiency points for each pressure value in order to reach the maximum power generated. Keywords: Combined cycle, heat recovery steam generator, pressure, efficiency, power, model.