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

: In this paper are investigated and presented the most influential operating parameters and the guidelines for proper arrangement of pumps in the condensing/feedwater heating system. The observed system operates in marine steam propulsion power plant. In the analyzed system operates three pumps: Condensate Pump (CP), Auxiliary Pump (AP) and FeedWater Pump (FWP). Considering all observed pumps, FWP is the dominant mechanical power consumer because it operates with the highest pressure difference and with the highest fluid mass flow rate. Used mechanical power and losses (energy and exergy) of all observed pumps are directly proportional to fluid mass flow rate through the pump – higher fluid mass flow rate through the pump will result with higher mechanical power used by pump and with higher losses (both energy and exergy) and vice versa. Energy and exergy efficiencies of the observed pumps have reverse proportional trends. The most influencing factor related to the pump efficiency (both energy and exergy) is the pump inlet pressure. Pump inlet pressure is directly proportional to the pump exergy efficiency, but simultaneously pump inlet pressure is reverse proportional to pump energy efficiency.

This paper shows analysis of each regenerative heater’s influence on global steam power plant operating parameters. Analysis is performed for nine steam power plant versions (configurations) – from the Base power plant without regenerative heating system up to the Final plant which consists of eight regenerative heaters (one mixing and seven non-mixing regenerative heaters). According to the defined fluid operating parameters throughout the plant, it is obtained that each new regenerative heater added to the plant continuously reduces the mechanical power produced by the turbine, for 4.33 MW on average. Simultaneously, each added regenerative heater increases feedwater temperature at the steam generator inlet, which results in power plant cumulative fuel consumption continuous decrease (for 0.414 kg/s on average) to obtain the same steam outlet parameters. Considering plant overall efficiency, it must be highlighted that each regenerative heater added to the plant continuously increases plant overall efficiency from the Base plant until the Final plant, for 0.43% on average.

In this paper is performed exergy and isentropic analysis of a helium closed-cycle gas turbine plant and all its main components. In the real operating conditions, turbine produces mechanical power equal to 546.27 MW, turbocompressor consumes mechanical power of 268.74 MW and the useful mechanical power delivered for the electric generator drive is equal to 277.53 MW. The highest possible mechanical power which can theoretically be delivered for the electrical generator drive (ideal useful mechanical power) is equal to 351.89 MW. Helium gas turbine is the component in the observed plant which has the lowest exergy destruction (9.40 MW) and the highest exergy efficiency (98.31%) of all components. Precooler has the lowest exergy efficiency of all plant components, equal to 47.66% only. Due to the usage of cooling water, precooler exergy parameters are highly sensitive to the ambient temperature change. Whole analyzed plant has exergy destruction of 261.79 MW and exergy efficiency of 48.69%, what is in the same range as for the comparable closed-cycle gas turbine plants.

Energy and exergy analyses results of steam turbine and steam condenser, which operate in commercial combined cycle power plant are presented in this paper. Energy analysis shows that steam turbine has high energy (isentropic) loss equal to 71.71 MW, and very low energy (isentropic) efficiency of 58.79% only. Simultaneously, steam condenser is an almost perfect component from the energy viewpoint. At the base ambient state, steam turbine has high exergy destruction of 61.80 MW and low exergy efficiency of 62.34%, so both used analyses show that steam turbine operation can and should be notably improved. Steam condenser has an exergy destruction of 17.12 MW and exergy efficiency of 55.17% at the base ambient state, what are acceptable results. Observed steam condenser is much more sensitive to the ambient temperature change than steam turbine. Increase in the ambient temperature from 5 °C to 35 °C decreases steam condenser exergy efficiency for 35.90%, while the same increase in the ambient temperature decreases steam turbine exergy efficiency for 2.39% only.

This paper presents exergy analysis results of a complex three cylinder steam turbine with nominal power 210 MW. The analysis is performed for each cylinder, cylinder part and whole turbine as well as for each segment of each turbine cylinder. In the observed turbine, Low Pressure Cylinder (LPC) has the highest exergy destruction (8668.15 kW) and the lowest exergy efficiency (87.19%), while Intermediate Pressure Cylinder (IPC) has the highest exergy efficiency (92.15%) of all cylinders. Exergy efficiency is the highest for each segment at each cylinder entrance and continuously decreases for all segments during steam expansion through each cylinder. In each cylinder, a segment which is the lowest influenced by the ambient temperature change is inlet segment – as steam expands through each cylinder, further segments became more and more influenced by the ambient temperature change. Steam re-heating process has a very beneficial influence on the exergy efficiency of the first two IPC segments (Seg. 3 and Seg. 4) which have the highest exergy efficiency in comparison to all other segments.

In this paper, an uncertainty analysis is performed related to the marine MAN B&W 6S70ME-C diesel engine. Uncertainty analysis is based on six different engine operating parameters (Maximum pressure, Compression pressure, Mean indicated pressure, Exhaust Gas Outlet Temperature, Cooling Fresh Water Outlet Temperature, and Piston Cooling Oil Outlet Temperature) measured in each engine cylinder. Various engine loads are observed. Exhaust Gas Outlet Temperature uncertainties are the highest in comparison to uncertainties of all other considered operating parameters. The highest Exhaust Gas Outlet Temperature uncertainty is detected at engine load of 90% and is equal to ±2.421%, while considering all observed engine loads, Exhaust Gas Outlet Temperature uncertainty is equal to ±4.296%. Overall uncertainty of the analysis performed in this paper (which considers all observed operating parameters at all engine loads) is equal to ±4.837%, which also falls within the range of the recommended uncertainty limit (±5%).

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, 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 how 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 energy and exergy analysis results of whole gas turbine set and all its components. From the energy viewpoint, combustion chamber has the lowest energy loss (21.31 MW) and the highest energy efficiency (97.20%) of all gas turbine set components. Exergy analysis shows totally opposite trend in comparison to the energy analysis. From the exergy viewpoint, turbocompressor and turbine have low exergy destruction (both around 12 MW) and very high exergy efficiencies (92.43% for turbocompressor and 96.12% for turbine) at the base ambient state. Simultaneously, at the base ambient state combustion chamber has an exergy destruction of 159 MW and low exergy efficiency of 73.29% only. The combustion chamber is the most sensitive to the ambient temperature change of all components from the gas turbine set – the ambient temperature change of 10 °C will result with combustion chamber exergy efficiency change of approximately 0.67%. Whole gas turbine set (plant) has an energy efficiency of 34.40% and exergy efficiency of 33.08%.

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.