Potential Improvements in Steam Power Plants: Heat
Recovery Systems, Operating Parameter Optimization,
Material Enhancements, and Efficiency Maximization
Improving the efficiency of steam power plants is critical to conserve fuel, minimize energy
losses, and minimize environmental emissions. Various engineering methods have been
conceptualized to improve performance, particularly in heat recovery, operating parameter
optimization, material advances, friction reduction, and combustion control.
1. Heat Recovery via Absorption Chillers
A highly effective means of boosting overall cycle efficiency is the application of waste heat
from the steam cycle. One such notable example is the use of absorption chillers that
replace traditional mechanical vapor compression (MVC) systems. The chillers are
powered by low- or high-pressure steam tapped off the system and utilize that heat energy
to produce cooling. This eliminates the need for electrically powered compressors in the
cooling systems, hence reducing parasitic electrical loads and improving the net efficiency
of the plant.
For Parehsar combined cycle power plant, the inclusion of absorption chillers in HRSG
allowed efficiency improvements up to 0.1%, a marginal but significant increase in overall
power generation. One also discovered that the extraction of steam after expansion is more
efficient than its pre-entry into turbines, since already some work had been extracted from
the steam.
2. Operating Parameter Optimization
The performance of a steam cycle is heavily reliant on some important operating
parameters:
•turbine Inlet Temperature (TIT): Increasing TIT from 450°C to 600°C yields up to a 5.2%
improvement in efficiency through enhanced energy extraction and reduced steam
moisture.
•steam-to-Gas Mass Flow Ratio (Z₂): Studies show that an optimal Z₂ ratio of 0.129
maximizes the use of steam energy in HRSG systems.
• Steam Extraction Fraction: Regulating the quantity of steam bypassed for regenerative
heating versus turbine expansion allows a balance between cycle efficiency and power
available.
0
