Chapter 5, Problem 5.2NP

The Chalk Point, Maryland, generating station supplies electrical power to the Washington, D.C., area. Units 1 and 2 have a gross generating capacity of 710. MW (megawatt). The steam pressure is $\text{25}\times \text{1}{0}^{\text{6}}\text{Pa}$, and the superheater outlet temperature $\left({\text{T}}_{\text{h}}\right)$ is $\text{54}0.°\text{C}$. The condensate temperature $\left({\text{T}}_{\text{c}}\right)$ is 30.0°C.

1. What is the efficiency of a reversible Carnot engine operating under these conditions?
2. If the efficiency of the boiler is 91.2%, the overall efficiency of the turbine, which includes the Carnot efficiency and its mechanical efficiency, is 46.7%, and the efficiency of the generator is 98.4%, what is the efficiency of the total generating unit? (Another 5.0% needs to be subtracted for other plant losses.)
3. One of the coal-burning units produces 355 MW. How many metric tons $\left(\text{1 metric ton}=\text{1}\times \text{1}{0}^{\text{6}}\text{g}\right)$ of coal per hour are required to operate this unit at its peak output if the enthalpy of combustion of coal is $\text{29}.0\times \text{1}{0}^{\text{3}}{\text{kJ kg}}^{-\text{1}}$?