A coal-fired power plant had been operating using a standard Rankine Cycle to produce power. The operating conditions are given in illustration 5.2-1. However, the boiler is aging and will need to be replaced. While waiting for the replacement, it has been suggested that for safety, the operating conditions be reduced from 600 oC to 400 oC. The plant operates with steam, with a condenser temperature of 100 oC, and in this emergency mode, the boiler would operate at 3.0 MPa and 400 oC.
a) Can the plant function in this mode? Why or why not?
b) A clever operator suggests that a Joule-Thompson value could be placed after the boiler and before the turbine. This valve is to be designed such that the exhaust from the turbine is at the same conditions as in Illustration 5.2-1, 0.10135 MPa, and approximately 126 oC. Assuming that the pump and turbine operate adiabatically and reversibly, fill in the missing values in the table associated with the problem.
c) Determine the heat and workflows per kg of steam in the pump, boiler, turbine, and condenser.
d) What is the efficiency of this new cycle? How does it compare the efficiency of the cycle in Illustration 5.2-1?
