Power Plants and

Processes

EEN-E1010, E1.

Shouzhuang Li

Energy Conversion research

group

Today’s program

•12:30 Energy conversion and performance parameters of steam power plant

•13:00 Example

•13:30 Exercise in group work, Q&A

Energy conversion of steam power plants

Boiler

Net electrical power output Pel,net

Performance parameters of steam power plants

Heat Rate HR

The amount of heat in kJ that is required to produce a unit power output kWh

Electrical (Overall) efficiency

Capacity factor CF

Example

• In a Rankine cycle steam power plant, the turbine receives 490 kg/s of steam at 200 bars and 550°C and the condenser pressure is 0.04 bar. The turbine and pump isentropic efficiencies are 0.92 and 0.83, respectively.

• Calculate: (a) the plant power output, (b) the plant thermal efficiency and (c) the plant heat rate.

P1 = 200 bars, T1= 550°C

P3 =0.04 bar

𝜂𝑖𝑠= 0.92

𝜂𝑝𝑢𝑚𝑝= 0.83

h1 = 3400 kJ/kg

h2s = 1920 kJ/kg

h2 = 2038.4 kJ/kg

Textbook Page 559

Group Work

• In a steam power plant, the turbine receives 700 kg/s of live steam at

• Group 1,4,7,10: 250 bars and 560 °C

• Group 2,5,8,11: 250 bars and 600 °C

• Group 3,6,9,12: 300 bars and 600 °C.

• The condenser pressure is 0.04 bar. The turbine isentropic efficiency is 0.92. The work of the feedwater pump can be neglected.

• 1. Draw the cycles in the T-s diagram

• 2. Calculate the plant’s thermal efficiency

• 3. Calculate the power plant net power output

Solutions

h1

[kJ/kg]

h2is

[kJ/kg]

h2

[kJ/kg]

h3

[kJ/kg] ηth

Net power

output [MW]

Group I 3380 1880 2000 121.41 0.423496 966

Group II 3490 1920 2045.6 121.41 0.428785 1011.08

Group III 3440 1860 1986.4 121.41 0.438017 1017.52