ABSTRACT
Heat recovery steam generator (HRSG) simulation is an interesting concept used to arrive at the thermal design as well as off-design performance of unred, red, simple or complex, multimodule, multipressure gas turbine HRSGs without physically sizing them. That is, one need not know about tube sizes, tube lengths, n geometry, surface area, or tube spacing and yet obtain the valuable information such as duty of each component of the HRSG, steam generation, burner fuel input in case of red HRSGs, performance with fresh air fan ring and performance at various gas turbine loads, and complete gas-steam temperature proles. Since energy transfer in almost all HRSGs is in convective mode, simulation techniques can be applied with good accuracy. One need not be an HRSG designer to determine the performance of any HRSG. Anyone who understands heat balance calculations can perform HRSG simulation. Hence, any plant or process engineer can obtain a lot of performance-related information about his HRSG even before it is purchased or designed. Simulation may also be used to nd out more information about an operating HRSG; for example, how will it perform if any gas-or steam-side parameter is changed or whether the HRSG is meeting performance guarantees as promised based on operating data. In the case of multimodule or multipressure HRSGs, simulation helps one to arrive at an optimum HRSG conguration and how the various heating surfaces should be arranged to maximize energy recovery. Examples in the following pages will illustrate the earlier points. Simulation will be helpful not only to plant or process engineers but also to HRSG suppliers who can optimize the HRSG conguration before even physically designing it.
