Page 136 - Handbook of Energy Engineering Calculations
P. 136
COMBINED-CYCLE PLANT HEAT-RATE COMPARISON
Compare the heat rate of a proposed conventional steam-power plant
generating electricity with that of a combined-cycle gas-turbine plant of the
same electrical capacity. Use the net plant heat rate at various generating
capacity loads as the basis for the comparison.
Calculation Procedure:
1. Obtain the heat rate for the proposed steam plant at various percent
rated capacities
Use data from the proposed plant design calculations, or from an existing
steam plant of the same output. Thus, for the proposed steam plant being
considered here, the heat rate at various loads is:
2. Determine the heat rate for the proposed combined-cycle plant
Use data from the proposed combined-cycle plant or from an existing similar
plant. Thus:
3. Plot the heat rates to show the comparison between the two plants
Figure 7 shows the heat rates for the two plants. As can be seen, the
