The incremental heat rate “the heat rate” is the ratio of input
fuel to the corresponding output power
From the incremental heat rate curve, the incremental fuel
rate is deduced With F is the input fuel and P is the output
power The reciprocal of the incremental fuel rate is known as
the incremental efficiency
To operate at the maximum fuel efficiency, the point of the
minimum heat rate has to be defined
Multiplying the incremental fuel rate by the fuel cost, the
incremental fuel cost is obtained in ($/MWh)
Example
The input fuel in (Btu/h) for a power plant with minimum and maximum power of 10 and 100 MW
respectively is given by:
F=(40+4*P + 0.012*P2)*106
where P is the generated power in (MW). Plot the input
output curve of the plant. Calculate the heat rate and plot its
curve against the output power.
Assuming a fuel cost of 0.12*10-6 $/Btu, calculate
the incremental fuel cost in $/MWh and plot its
curve against the output power.
The fuel is given as:
F=(40+4*P + 0.012*P2)*106
Also, the heat rate can be calculated from equation
Heat rate = The fuel cost as a function of the output power is:
C=0.12*10-6 *F= 4.8 + 0.48*P + 0.0014*P2 ($/h)
The incremental fuel cost is:
Ifr = 0.48 + 0.0028*P ($/MWh)