Consider 1100 degree F 2000 psia 5 psia Kankine cycle with 8

Consider 1100 degree F 2000 psia, 5 psia Kankine cycle with 85% turbine efficiency and 60% pump efficiency. The cycle is operating with a single reheat to 1100 degree F at 1000 psia. Calculate: 1) the heat addition in the steam generator? 2) Actual work of each turbine? 3) Actual work of the pump? 4) Condenser heat rejection? 5) The thermal efficiency of the reheat cycle? Using:

Solution

FROM MOLLIER DIAGRAM

ENTHALPIES AT DIFFEENT POINTS ARE AS FOLLOWS

h1=3600KJ/Kg at HP TURBINE INLET

h2=2773KJ/Kg at HP TURBINE OUT LET

STEAM IS REHEATED UN REHEATER UPTO1100 FAHREIGHNHEAT

AT THIS POINT h3=3650KJ/Kg

STEAM IS EXPANDED IN LP TURBINE UPTO 5psia=.34bar

at this point h4=2630KJ/Kg AT 5psia enthalpy of steam in liquid state is =300kj/kg

1)HEAT ADDED IN STEAM GENERATOR PER Kg OF STEAM= M(h1-h4)= 1*(3600-300 )=3300kW

2)ACTUAL WORK OF TURBINE=WORK DONE IN HP TURBINE+WORKDONE IN LP TURBINE

=(3600-2773)+(3650-2630)=1907KW

turbine is having .85 ejjicienvcy

turbine work=0.85*1907=1620 kw

3)HEAT REJECTED IN CONDENSOR PER Kg of steam =1*(2630-300)=2330 KW

4)THERMAL EFFICIENCY=WORK DONE/HEAT SUPPLIED

=1620/3300=0.491

=49.1%

5)WORK OF PUMP= M*(ENTHALPY PF STEAM LEAVING CONDENSOR) =1*300=300KW