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

Exergy analysis of three cylinder steam turbine segments is performed in this research. The highest mechanical power of 47389.66 kW is developed in the first segment (Seg. I, which actually represents the entire HPC – High Pressure Cylinder). Intermediate Pressure Cylinder (IPC) is the dominant mechanical power producer of all cylinders and it develops 48.95% of cumulative mechanical power produced in the whole turbine. The outlet Low Pressure Cylinder (LPC) segments (Seg. VII and IX) have the highest exergy destructions and the lowest exergy efficiency (equal to 61.27%) of all turbine segments. The best exergy performance shows IPC segments – Seg. V has the lowest exergy destruction (equal to 363.84 kW), while Seg. II has the highest exergy efficiency (equal to 94.04%) of all turbine segments. Outlet LPC segments (Seg. VII and IX) are the most sensitive to the ambient temperature change – their exergy efficiency decreases for 3.19% when the ambient temperature increases from 5 °C to 45 °C.

This paper presents results of two different isentropic analysis types: conventional isentropic analysis which considers the whole steam turbine cylinder and segmental isentropic analysis which considers all cylinder parts (segments). In conventional isentropic analysis is obtained that isentropic efficiency of the analyzed turbine is 73.39%, what is in a range of expected isentropic efficiencies for such steam turbines (in the mechanical power range around 60 MW). Segmental isentropic analysis shows that the last two segments (fifth and sixth segment) of the analyzed turbine did not show proper operation (especially the fifth turbine segment which isentropic efficiency is unacceptably low and equal to 26.73% only). Such isentropic efficiency results, related to the fifth and sixth turbine segment, indicate highly problematic operation, or the most likely malfunction of at least some turbine stages in these segments. For the analyzed steam turbine can be recommended that it should be stopped as soon as possible and that turbine stages mounted in the last two segments should be checked, repaired or replaced.

In this paper is performed energy analysis of the whole low power steam turbine as well as energy analysis of all the turbine segments. Analysis of the whole turbine resulted with energy loss of 14642.48 kW and energy efficiency of 75.01%, what is in range with similar comparable low power steam turbines. Energy analysis of the turbine segments presents a different conclusion than the energy analysis of the whole turbine. The fifth turbine segment (S5) has unacceptable high energy loss and unacceptable low energy efficiency (energy loss of 6785.93 kW and energy efficiency of 26.87%), so it should be repaired as soon as possible. This comparison sh ow that proper energy analysis of turbine parts (segments) can detect the precise location of the problems during the turbine operation. Such analysis can be very helpful for the engineers because it allows detection not only the problematic components in the power plant, but also allows detection of the problematic parts of a component.