Prob_04

Turbina de GAS (Ciclo Brayton)

1. Brayton Cycle with Intercooling, Reheat & Regeneration

A regenerative gas turbine with intercooling and reheat operates at steady state. Air enters the compressor at 100 kPa, 300 K with a mass flow rate of 5.807 kg/s. The pressure ratio across the two-stage compressor is 10. The pressure ratio across the two-stage turbine is also 10. The intercooler and reheater each operate at 300 kPa. At the inlets to the turbine stages, the temperature is 1400 K. The temperature at the inlet to the second compressor stage is 300 K. The isentropic efficiency of each compressor and turbine stage is 80%. The regenerator effectiveness is 80%. {Los datos y figura del pb. están en el archivo adjunto Bryt_cycL.pdf} Determine:

a) The thermal efficiency

b) The net power developed (kW)

c) The Heat Rate

d) The energy recovered in the regenerator

 Nota: La solución que "realizamos" en clase está en los archivos adjuntos Brayt01.* ; pero no coincide con la del pdf original... quién puede especificar dónde está el error???

2. Cogeneration Plant

A cogeneration plant is to generate power and process heat. Consider an ideal cogeneration steam plant. Steam enters the turbine from the boiler at 7 MPa, 500 C and a mass flow rate of 30 kg/s. One-fourth of the steam is extracted from the turbine at 600-kPa pressure for process heating. The remainder of the steam continues to expand and exhausts to the condenser at 10 kPa. The steam extracted for the process heater is condensed in the heater and mixed with the feedwater at 600 kPa. The mixture is pumped to the boiler pressure of 7 MPa. Show the cycle on a T-s diagram with respect to saturation lines, and determine: {answers}

1) the heat transfer from the process heater per unit mass leaving the boiler {Qdot,process = 15,774 kW}.

2) the net power produced by the cycle. {Wdot,net = 32,848 kW}.

3) the utilization factor of the plant {Qdot,in = 92,753 kW, Utilization factor = 52.4%}.

3. Para el Ciclo Combinado: " The rule of thumb for combined cycle power plants is that you will be able to produce approximately 0.5 MW with a steam turbine for every MW produced by the gas turbine, for the same fuel flow-rate (presuming no extractions)."

Con base en esta regla estimada, diseñe el ciclo combinado (generado potencia con vapor) considerando el equipo necesario para lograr el objetivo. Para los datos del ciclo Brayton (TG) utilice los del Pb (1), arriba citados, y solo reemplace el regenerador por el recuperador de calor de la figura siguiente.