Problem # p004

Boiler-turbine, conservation of energy, actual vs. Carnot efficiency

The figure below despicts schematically a power plant cycle containing a turbine which is fed from a boiler with superheated steam and exhausts saturated steam at lower pressure into a condensor. Due to poor insulation the turbine looses heat at a rate of 1000 kJ/s.

  1. At which rate (kg/s) must steam be provided to the turbine in order for the turbine to have a power output of 10 MW ?

  2. At what rate [kJ/s] must heat be transferred to the water inside the boiler ?

  3. What is the efficiency (benefits/costs) of the turbine if the costs consists of the heat transferred inside the boiler ? You may neglect the work needed by the pump.

  4. What would the efficiency of a Carnot cycle be if it were to operate between the temperature of the superheated steam entering the turbine and the temperature of the exiting saturated steam ?