Design methodology of heat recovery steam generator in electric utility for waste heat recovery

Heat recovery steam generators (HRSGs) are important components for industrial waste heat recovery, and any changes in their design directly affect the performance of the steam cycle, and thus the performance of the combined cycle power plant. The present research is focused on the design of a HRSG, including a dual-pressure steam generator cycle that is intended for use in a typical gas turbine unit having a power output of 60 MW. The results show that the maximum heat transfer occurs in the evaporator section for high-pressure levels, and in the economizer section for low-pressure levels. The optimum design pressure for the high-pressure level of the steam generator was found to be 100 bar, while that for the low-pressure level was found to be 10 bar. An exergy analysis was performed for the different processes and components of the steam cycle, including the HRSG. Calculations show that the overall exergy loss is about 35%, out of which 16% is lost in flue gasses and 10% is lost in heat exchanger, and the remainder was converted into 35 MW of useful work.