# Waste-heat power (steam Rankine)

Hot exhaust raising steam for a turbine in cement, steel, glass and acid plants, and in combined-cycle plants.

Source page: https://www.materialinsights.org/energy/e_whr_rankine/

Recovery and reuse · Heat to power and cogeneration · No. 125

- Recovery and reuse
- Heat grade: Medium to high
 Recovery and reuse · Heat to power and cogeneration · Foundation · Energy

A gas turbine alone turns about 43% of fuel into power; a steam cycle on its exhaust lifts that to 64%.

Chart: Illustration: Waste-heat power (steam Rankine)

##### Where it comes from

Chart: Map of where it comes from

Steady exhaust above about 230 C, from gas turbines, cement preheaters and big engines, can raise steam to spin a turbine. In combined-cycle plants the steam side supplies about a third of the output.

##### Three things to know

1. Real steam cycles reach only 30-50% of the Carnot limit, so cement exhaust near 300 C yields roughly 14-24% as power.
2. Cement kiln gas carries about 35-125 g of dust per cubic metre, so WHR boilers need hoppers and rapping to stay clean.
3. One 13 MW Chinese cement unit makes 79.29 GWh a year and avoids 51,419 t of CO2.

##### The journey

1. 1 **Hot exhaust**Kiln, turbine or engine gas above 230 C
2. 2 **WHR boiler**Raises steam from the exhaust heat
3. 3 **Steam turbine**Spins a generator to make power
4. 4 **Condenser**Water or air cools spent steam
5. 5 **Power used**Up to 25-30% of a cement plant's electricity

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_whr_rankine/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_whr_rankine/correlation/index.md)
- [Science and thermodynamics](https://www.materialinsights.org/energy/e_whr_rankine/rc-sci/index.md)
- [Engineering and integration](https://www.materialinsights.org/energy/e_whr_rankine/rc-eng/index.md)
- [Economics and contracts](https://www.materialinsights.org/energy/e_whr_rankine/rc-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_whr_rankine/rc-impact/index.md)
- [What to track](https://www.materialinsights.org/energy/e_whr_rankine/tracking/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_whr_rankine/links/index.md)