International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This paper presents thermodynamic (energy and exergy) analysis of backpressure (BPT) and condensing (CT) steam turbines from cogeneration system. Based on the measurement data from exploitation it is performed calculation of main operating parameters for both turbines and its comparison. Analysis shows that BPT develops significantly lower mechanical power (22821.90 kW) in comparison to CT (30893.10 kW), but also BPT has more than four times lower energy and exergy power losses when compared to CT. Due to much lower losses, BPT has significantly higher energy and exergy efficiencies (93.26% and 94.95%, respectively) in comparison to CT (82.63% and 83.87%, respectively). Energy and exergy power of a steam flow related to both observed turbines show that the BPT is the dominant heat supplier for all heat consumers inside the cogeneration system.

The paper present thermodynamic analysis of three-cylinder steam turbine, which operates in a combined cycle power plant. It is performed analysis of each turbine cylinder and of entire steam turbine. Comparison of steam turbine cylinders shows that intermediate pressure cylinder develops the highest real power and has the highest efficiencies while low pressure cylinder has the highest ideal (isentropic) power, the highest loses and the lowest efficiencies – therefore, improvement potential of the low pressure cylinder is the highest. Entire observed steam turbine has an energy efficiency equal to 86.58 % and exergy efficiency equal to 89.26 %, what is lower in
comparison to high power steam turbines from some conventional land-based steam power plants but also higher in comparison to low power marine steam turbines.