• MATHEMATICAL MODELLING OF TECHNOLOGICAL PROCESSES AND SYSTEMS

    60 MW steam turbine conventional and segmental isentropic analyses comparison

    Mathematical Modeling, Vol. 7 (2023), Issue 2, pg(s) 45-48

    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.

  • MACHINES

    Exergy analysis of steam turbine from ultra-supercritical power plant

    Machines. Technologies. Materials., Vol. 17 (2023), Issue 3, pg(s) 98-101

    In this paper is presented an exergy analysis of steam turbine (along with analysis of each cylinder and cylinder part) from ultrasupercritical power plant. Observation of all the cylinders shows that IPC (Intermediate Pressure Cylinder) is the dominant mechanical power producer (it produces mechanical power equal to 394.44 MW), it has the lowest exergy loss and simultaneously the highest exergy efficiency (equal to 95.84%). HPC (High Pressure Cylinder) has a very high exergy efficiency equal to 92.37% what confirms that ultrasupercritical steam process is very beneficial for the HPC (and whole steam turbine) operation. LPC (Low Pressure Cylinder) is a dissymmetrical dual flow cylinder, so both of its parts (left and right part) did not produce the same mechanical power, did not have the same exergy loss, but their exergy efficiency is very similar and in a range of entire LPC exergy efficiency (around 82.5%). Whole observed steam turbine produces mechanical power equal to 928.03 MW, has exergy loss equal to 93.45 MW and has exergy efficiency equal to 90.85%. The exergy efficiency of the whole analyzed steam turbine is much higher in comparison to other steam turbines from various conventional power plants.

  • MACHINES

    The influence of steam extractions operation dynamics on the turbine efficiencies and losses

    Machines. Technologies. Materials., Vol. 17 (2023), Issue 1, pg(s) 3-6

    In this paper are presented results of a low-pressure steam turbine energy and exergy analysis during turbine extractions opening/closing. All possible combinations of extractions opening/closing are observed. The highest mechanical power which can be produced by this turbine (when all steam extractions are closed) is 28017.48 kW in real and 31988.20 kW in an ideal situation. For all observed steam extractions opening/closing combinations is obtained that energy efficiency and energy losses range is relatively small (from 87.56% to 87.94% for energy efficiency and from 3360.46 kW to 3970.72 kW for energy losses). Trends in energy and exergy losses (destructions) are identical for all observed extractions opening/closing combinations. Analyzed turbine efficiencies (both energy and exergy) will decrease for a maximum 1% during the steam extractions closing. Turbine steam extractions closing decrease turbine efficiencies and increases turbine losses (destructions), what is valid from both energy and exergy aspects.

  • MACHINES

    Energy analysis of a steam turbine with two cylinders and steam re-heating

    Machines. Technologies. Materials., Vol. 16 (2022), Issue 5, pg(s) 155-158

    This paper presents an energy analysis of middle-power steam turbine with two cylinders (High Pressure Cylinder – HPC and Low Pressure Cylinder – LPC) and steam re-heater after the HPC (and before the LPC). Based on a steam operating parameters from the literature, performed energy analysis show that LPC develops higher power and has higher energy efficiency (81.45%) in comparison to HPC (which energy efficiency equals 80.12%). Re-heater is a heat exchanger (flue gases are used for steam heating) which has low energy loss (824.19 kW) and high energy efficiency (97.76%), what is expected energy performance of such heat exchanger. The entire analyzed turbine develops a power of 127480.60 kW and has energy loss equal to 29848.21 kW with energy efficiency of 81.03%.

  • MACHINES

    Energy evaluation of a steam turbine from solar-based combined cycle power plant

    Machines. Technologies. Materials., Vol. 16 (2022), Issue 3, pg(s) 86-89

    In this paper is performed energy evaluation of steam turbine from the solar-based combined cycle power plant which includes analysis of each cylinder and the whole turbine. Steam turbine has three cylinders – high, intermediate and low pressure cylinders (HPC, IPC and LPC). Observed turbine is interesting because it possesses steam cooling before its expansion through the last cylinder (LPC). Due to unknown steam mass flow rates through each cylinder, for the evaluation are used specific variables. The highest specific work is obtained in LPC, while the lowest specific work is obtained in IPC. The highest loss of a specific work is obtained in LPC (29.8 kJ/kg), followed by HPC (24.5 kJ/kg), while the lowest loss of a specific work is obtained for the IPC (19.5 kJ/kg). Regardless of higher loss in specific work, HPC has higher energy efficiency in comparison to IPC (95.08% in comparison to 95.02%), while the lowest energy efficiency of all cylinders has LPC (94.92%). For the whole observed steam turbine loss of a specific work is equal to 73.8 kJ/kg, while the energy efficiency of the whole turbine is 95.00%.

  • INNOVATIVE SOLUTIONS

    Energy (isentropic) analysis of three-cylinder steam turbine with re-heating

    Innovations, Vol. 8 (2020), Issue 1, pg(s) 37-40

    In this paper is presented energy (isentropic) analysis of high power, three-cylinder steam turbine with steam re-heating. A comparison of real (polytropic) and ideal (isentropic) steam expansion processes at nominal load show that observed turbine develops real power of 655.35 MW, while in ideal situation it can develop 716.18 MW. The highest energy loss and the lowest energy efficiency occur in the high pressure turbine cylinder (25.67 MW and 89.14%), while intermediate pressure cylinder has the highest energy efficiency and the lowest energy loss. The energy efficiency of the whole observed turbine is 91.51%, what is in the expected range for such high power steam turbines at nominal load. Further optimization of this steam turbine will be primarily based on the high pressure cylinder.

  • MACHINES

    Thermodynamic analysis of three-cylinder steam turbine from combined cycle power plant

    Machines. Technologies. Materials., Vol. 14 (2020), Issue 2, pg(s) 61-64

    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.

  • Numerical analysis of turbo-generator steam turbine energy efficiency and energy power losses change during the variation in developed power

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 1, pg(s) 11-14

    Developed power variation of turbo-generator (TG) steam turbine allows insight into the change of turbine energy efficiency and energy power losses. Measurements were performed in five different TG steam turbine operating points and analysis is presented in three randomly selected operating points. Turbine developed power was varied from 500 kW until the maximum power of 3850 kW in steps of 100 kW. Turbine energy efficiency increases from 500 kW to 2700 kW and maximum energy efficiency was obtained at 70.13 % of maximum turbine power (at 2700 kW) in each operating point. From 2700 kW until the maximum of 3850 kW, TG turbine energy efficiency decreases. Change in TG turbine energy efficiency is caused by an uneven intensity of increase in turbine power and steam mass flow. For all observed operating points, energy efficiency during turbine exploitation is approximately 10 % or more lower than the maximum obtained one. A continuous increase in turbine energy power losses during the developed turbine power increase are the most influenced by the continuous increase in steam mass flow through the turbine.

  • MACHINES

    ENERGY EFFICIENCY AND ENERGY POWER LOSSES OF THE TURBOGENERATOR STEAM TURBINE FROM LNG CARRIER PROPULSION SYSTEM

    Machines. Technologies. Materials., Vol. 12 (2018), Issue 1, pg(s) 12-15

    Turbo-generator (TG) steam turbine energy efficiency and energy power losses in a wide range of turbine loads were presented in this analysis. For TG steam turbine was investigated influence of steam specific entropy increment from the real (polytropic) steam expansion on energy power losses and energy efficiency. TG turbine energy power losses, during the all observed loads, were in the range from 646.1 kW to 685.5 kW. The most influenced parameter which defines change in TG turbine energy power losses is steam mass flow change, while for small steam mass flow changes, influence of steam specific entropy increment on steam turbine energy power losses is the most influential. Steam specific entropy incremental change can be used to estimate the change of TG steam turbine energy efficiency. Increase in steam specific entropy increment resulted with a decrease in TG turbine energy efficiency and vice versa. Analyzed steam turbine energy efficiency ranges from 53.84 % to 60.12 %, what is an expected range for low power steam turbines.