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

In this paper are presented isentropic analysis results of a steam turbine, their cylinders and cylinder parts which nominal power is equal to 250 MW. The analyzed steam turbine is a complex three-cylinder turbine which operates in a CCPP (Combined Cycle Power Plant). Considering all cylinders, the dominant mechanical power producer in the observed turbine is LPC (Low Pressure Cylinder) which produces 111.80 MW of mechanical power in real (polytropic) steam expansion process (almost half of the real mechanical power produced in the whole turbine). Developed mechanical power in turbine cylinders and isentropic losses are directly proportional – higher produced mechanical power will result in higher isentropic losses and vice versa. Whole analyzed steam turbine, their cylinders and cylinder parts show very good isentropic performance and high isentropic efficiencies of around 90%. The isentropic performance of the whole analyzed steam turbine, their cylinders and cylinder parts is in the range of the steam turbines (and their cylinders) from supercritical and ultrasupercritical power plants which are proven to be the best steam turbines from isentropic point of view.

This paper presents an exergy analysis of six pressure reduction valves which operate in a condensate/feedwater heating system of a 660 MW coal-fired steam power plant. For all observed pressure reduction valves is additionally investigated the ambient temperature change influence of their exergy parameters. Second pressure reduction valve (PRV2) has the highest exergy destruction of all observed valves (equal to 1003.36 kW at the base ambient state). The first five observed pressure reduction valves (from PRV1 to PRV5) have very high exergy efficiencies at the base ambient state, higher than 90%. The last observed valve, PRV6, has an exergy efficiency at the base ambient state notably lower in comparison to other five valves, equal to 64.90% only. The exergy variables of any pressure reduction valve are more and more influenced by the ambient temperature change when the operating parameters of working fluid which flows through the valve (fluid pressure and temperature) are closer to the ambient state.

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 an exergy analysis of a two-cylinder low power steam turbine from combined cycle power plant at three operating regimes. The highest mechanical power produced in the whole turbine is 6807.24 kW in Operating regime 1. Cylinders of the observed turbine did not have the same operation dynamics in relation to produced mechanical power in all operating regimes. In each operating regime High Pressure Cylinder (HPC) has lower exergy destruction and higher exergy efficiency in comparison to Low Pressure Cylinder (LPC) due to the influence of wet steam which expands through the last LPC stages (water droplets in wet steam increases LPC exergy destruction and decreases LPC exergy efficiency). Whole turbine exergy efficiency is between 51.62% (in Operating regime 2) and 64.98% (in Operating regime 1). This range of exergy efficiencies can be expected for a low power steam turbine. An increase in the ambient temperature decreases exergy efficiency of the whole turbine and both turbine cylinders, regardless of the observed operating regime. The exergy efficiency of the LPC is low in all operating regimes, so any improvements should be based on this cylinder first.

In this paper is performed exergy analysis of steam re-heating system, through all of its components, which operate in nuclear power plant. Analyzed re-heating system consists of the moisture separator (MS) and two re-heaters (RH1 and RH2) and is observed in four different operating regimes. MS has significantly lower exergy destructions and significantly higher exergy efficiencies in comparison to both re-heaters, regardless of the observed operating regime. MS and both re-heaters did not achieve the lowest exergy destructions and the highest exergy efficiencies in the same operating regime which notably complicated possible improvements. Further research of presented re-heating system will be based on operation improvement of RH1 and RH2 – performed exergy analysis shows that MS operation in any operating regime leaves no room for further improvement.

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.

This paper presents an energy analysis of a three-cylinder steam turbine from a combined cycle power plant. Observing all the cylinders from the analyzed turbine, it is found that the dominant mechanical power producer is Low Pressure Cylinder (LPC), followed by the Intermediate Pressure Cylinder (IPC), while High Pressure Cylinder (HPC) is the cylinder which produces the lowest mechanical power. Whole observed steam turbine develop 119.41 MW of useful mechanical power. Energy loss and energy efficiency of all cylinders are reverse proportional – higher energy efficiency will result with lower energy loss and vice versa. IPC is the cylinder which has the lowest energy loss (equal to 2.59 MW) and the highest energy efficiency of 93.32%. Whole observed steam turbine has energy loss equal to 23.43 MW, while its energy efficiency is equal to 83.60%, what falls in the expected range of such low power steam turbines. Steam mass flow rate through each cylinder is the main element which defines produced mechanical power and energy flows.

In this paper is performed exergy analysis of three cylinder steam turbine from the supercritical coal-fired power plant. Exergy analysis parameters were calculated for the whole turbine and each cylinder for the ambient temperature range between 5 °C and 45 °C. The dominant mechanical power producer of all the cylinders is a low pressure cylinder (LPC) which produces 262.06 MW of mechanical power. An increase in the ambient temperature increases exergy destructions and decreases exergy efficiencies of the whole turbine and each cylinder. Exergy analysis shows that LPC is a cylinder with the highest exergy destruction (between 24.67 MW and 28.24 MW) and the lowest exergy efficiency (between 82.27% and 84.16%) in comparison to the other cylinders. Exergy destruction of the whole observed turbine is between 67.85 MW and 77.62 MW, while the whole turbine exergy efficiency ranges between 89.47% and 90.67%. Inside the observed steam turbine, LPC is the most influenced by the ambient temperature change, therefore future research and possible optimization should be specifically based on this cylinder.

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.

This paper presents a comparison of three methods for any pump energy analysis. Each method is used for the analysis of three different water pumps from the conventional steam thermal power plant – two feed water pumps (FWP1 and FWP2) and condensate pump (CP). For each pump three essential types of mechanical power which defines all energy analysis methods are: delivered power from power producer, real (polytropic) power and ideal (isentropic) power. Method 1 which compares delivered and real (polytropic) power show the best performances, while Method 3 which compare delivered and ideal (isentropic) power should be avoided because it results with too high energy power loss and too low energy efficiency of any pump. Method 2 which compares real (polytropic) and ideal (isentropic) pump power can be used as a good compromise for the pump energy analysis in the most of the cases – its results are similar to results of Method 1.

In this paper is performed energy analysis of the dual-flow dissymmetrical low pressure steam turbine, which operates in a coalfired power plant. Based on the measured operating parameters during exploitation it is calculated and presented an ideal and real power, energy losses and energy efficiencies of a whole turbine and both of its cylinders. Right cylinder of the analyzed turbine develops higher real (polytropic) and ideal (isentropic) power in comparison to left turbine cylinder. The first steam extraction of each cylinder dictates cylinder power (both ideal and real). Right cylinder has a higher energy loss and energy efficiency in comparison to left cylinder – the difference in energy loss is notable (5735.74 kW in comparison to 5447.23 kW), while the difference in energy efficiency is low, almost negligible (92.371% in comparison to 92.357%). Percentage differences between observed turbine cylinders show that left cylinder has approximately 5% lower real (polytropic) as well as ideal (isentropic) power and simultaneously approximately 5% lower energy loss.

This paper present analysis of energy flow streams through the main steam turbine (the turbine is used for commercial LNG carrier propulsion) at three different loads. An increase in the propulsion plant (and proportionally increase in the main turbine) load resulted with an increase in energy flow streams and with an increase in the amount of water droplets inside steam at the main turbine outlet. Analyzed turbine has three steam extractions which opening as well as the amount of energy flow stream delivered through each extraction, significantly differs at various loads. The analysis shows that the highest energy flow stream consumers from the main turbine are deaerator and high pressure feed water heating system.