(Solved):   04 Consider the combined gas-steam power cycle shown in the figure. The gas- turbine cycle ...

 

04 Consider the combined gas-steam power cycle shown in the figure. The gas- turbine cycle that has a pressure ratio of 8. Air enters the compressor at 300 K and the gas turbine at 1300 K. The steam Rankine cycle has a 20 kPa within the condenser. Steam is generated in the HRSG at a temperature of 350 °C and 50 bar using the exhaust gases. The exhaust gases leave HRSG to the stack at 450 K. The aimed power from the combined cycle is 200 MW. The HRSG height is 25 m Determine: (a) the mass flow rates of the steam and the combustion gases (b) the thermal efficiency of the combined cycle (c) the temperature and pressure of hot gases and the stem at each point( if not given) d) area of superheater and economizer f) Recirculation pressure, number of risers and downcommers g) fuel mass flow rate (CV-22000 kJ/kg) Assume specific heat of gases 1.1 kJ/kg °C. counter flow and 37 W/m² °C overall coefficient of heat transfer in the economizer and 24 W/m² °C overall coefficient of heat transfer in the superheater. Also, you can assume the isentropic efficiency of gas turbine and compressor within range in 0.8 to 0.9) Clear your assumptions Fuel mr Combustion chamber Ma -b Compressor 9 Evap Fresh air a C gas turbine Exhaust gases P and T at turb. inlet d Wort steam turbine 2 P cond. SU WW e risers pump condenser 3 74 f down 4 5 ECO gases to stack