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

The results of three turbomachines (one turbocompressor and two turbines) isentropic and exergy analyses, which operate in supercritical CO2 power plant are presented in this paper. Both observed turbines (Turbine 1 and Turbine 2) have higher improvement potential than Turbocompressor. Mechanical losses in power transmission between Turbine 1 and Turbocompressor are equal to 456.57 kW in real operation process. Turbocompressor has the highest isentropic efficiency of 96.87% and the highest exergy efficiency of 97.61% if all observed turbomachines are considered. Turbine 2 used for the electric generator drive has higher efficiencies (both isentropic and exergy) in comparison to Turbine 1, regardless of higher isentropic loss and higher exergy destruction. Increase in the ambient temperature from 5 °C up to 45 °C decreases Turbocompressor exergy efficiency for 0.31%, while the same ambient temperature increase decreases exergy efficiency of both turbines for 0.53% (Turbine 1) and for 0.52% (Turbine 2).

In this paper are presented results of the isentropic analysis related to the cylinders, segments and whole three cylinder steam turbine from the conventional power plant. In the analyzed steam turbine Low Pressure Cylinder (LPC) is the dominant mechanical power producer of all cylinders – it produces 130.16 MW of mechanical power in the real expansion process and it can produce 142.80 MW of mechanical power if the expansion conditions are ideal. The satisfactory isentropic performance of the whole High Pressure Cylinder (HPC) is a combination of two segment’s isentropic performance – one of these segments show extremely good isentropic performance (Seg2), but another segment (Seg1) shows very poor isentropic performance. Both Intermediate Pressure Cylinder (IPC) segments (Seg3 and Seg4) show similar isentropic performance, what result with the balanced IPC operation. LPC has an isentropic efficiency of 91.15%, what is the highest isentropic efficiency of all cylinders from the observed steam turbine. Whole observed steam turbine has an isentropic efficiency of 88.42% what is better isentropic performance in comparison to similar steam turbines from conventional power plants.

In this paper are presented isentropic analysis results of a steam turbine and each of its cylinders which operate in Municipal Solid Waste (MSW) power plant. Low Pressure Cylinder (LPC) which produces the highest real mechanical power has the lowest isentropic loss of all cylinders equal to 4344.75 kW, while High Pressure Cylinder (HPC) which produces the lowest real mechanical power has the highest isentropic loss of all cylinders equal to 5204.54 kW. Isentropic losses and isentropic efficiencies are reverse proportional, because the cylinder with the lowest isentropic loss (LPC) has the highest isentropic efficiency equal to 88.92%, while the cylinder with the highest isentropic loss (HPC) has the lowest isentropic efficiency equal to 84.58%. Surprisingly, isentropic efficiency of the Intermediate Pressure Cylinder (IPC) is equal to 86.80% only, which is higher in comparison to HPC but notably lower than LPC. The observed turbine strongly differs from other comparable steam turbines from the literature where IPC has notably higher isentropic efficiencies than both HPC and LPC. Whole observed steam turbine produces real mechanical power equal to 97513 kW, while its isentropic efficiency is equal to 86.87%.

This paper presents results of the Main Feedwater Pump (MFP) isentropic and exergy analyses at three power plant loads. Observed MFP is a constituent component of condensate/feedwater sub-system from conventional steam power plant. In real exploitation conditions, MFP uses mechanical power higher than 3000 kW, considering all observed power plant loads. Main isentropic and exergy parameters of the MFP at various plant loads show the same general trends (increase in power plant load simultaneously increases MFP losses and efficiencies and vice versa, from both isentropic and exergy viewpoints). Analyzed MFP has high isentropic and exergy efficiencies, considering all plant loads and ambient temperatures (at any plant load MFP isentropic efficiency is higher than 85%, while the lowest MFP exergy efficiency is equal to 89.24% at the lowest observed plant load and the highest observed ambient temperature). The change in isentropic and exergy efficiency of the MFP is small if all observed plant loads and ambient temperatures are taken into consideration.

This paper presents isentropic analysis results of the whole steam turbine (as well as turbine cylinders) from nuclear power plant. In the analyzed steam turbine, LPC (Low Pressure Cylinder) is the dominant mechanical power producer – mechanical power produced in the LPC is more than two times higher in comparison to mechanical power produced in the HPC (High Pressure Cylinder). Whole analyzed steam turbine produces real mechanical power equal to 1372.47 MW, while the highest possible mechanical power which can be produced in the whole turbine when all the losses are neglected (ideal mechanical power) equals 1686.96 MW. LPC has a notably higher isentropic efficiency than HPC, regardless of higher isentropic loss (isentropic efficiencies of the LPC and HPC are 84.41% and 74.84%, respectively). HPC has notably higher specific steam consumption and specific heat consumption in comparison to LPC. Whole turbine has an isentropic efficiency equal to 81.36%, isentropic loss equal to 314.48 MW, specific steam consumption of 9.15 kg/kWh and specific heat consumption of 3799.06 kJ/kWh, what is in the range of similar comparable steam turbines from nuclear power plants.

In this paper is performed an isentropic analysis of the entire Intermediate Pressure Cylinder (IPC) and all of his four Segments. Obtained results show that the first Segment (Seg. 1) is the dominant mechanical power producer of all Segments and it produces 16816.70 kW of mechanical power in the real (polytropic) expansion process. Analyzed IPC produces more than half mechanical power of the entire turbine in which he operates (in real expansion process IPC produces mechanical power equal to 58499.48 kW). Isentropic loss and isentropic efficiency of IPC Segments are reverse proportional – Seg. 3 which has the highest isentropic loss simultaneously has the lowest isentropic efficiency (equal to 82.44%), while Seg. 4 which has the lowest isentropic loss has the highest isentropic efficiency (equal to 87.26%). Entire IPC has an isentropic efficiency equal to 87.78%. Any improvements and modifications which can potentially be performed in the observed IPC should firstly be based on the turbine stages mounted inside Seg. 3.