Exergetic and parametric study of a solar aided coal-fired power plant

A solar-aided coal-fired power plant realizes the integration of a fossil fuel (coal or gas) and clean energy (solar). In this paper, a conventional 600 MW coal-fired power plant and a 600 MW solar-aided coal-fired power plant have been taken as the study case to understand the merits of solar-aided power generation (SAPG) technology. The plants in the case study have been analyzed by using the First and Second Laws of Thermodynamics principles. The solar irradiation and load ratio have been considered in the analysis. We conclude that if the solar irradiation was 925 W/m2 and load ratio of the SAPG plant was 100%, the exergy efficiency would be 44.54% and the energy efficiency of the plant (46.35%). It was found that in the SAPG plant the largest exergy loss was from the boiler, which accounted for about 76.74% of the total loss. When the load ratio of the unit remains at 100%, and the solar irradiation varies from 500 W/m2 to 1,100 W/m2, the coal savings would be in the range of 8.6 g/kWh to 15.8 g/kWh. If the solar irradiation were kept at 925 W/m2 while the load ratio of the plant changed from 30% to 100%, the coal savings could be in the range of 11.99 g/kWh to 13.75 g/kWh.Rongrong Zhai, Yong Zhu, Yongping Yang, Kaiyu Tan and Eric H

A critical review on energy, exergy, exergoeconomic and economic (4-E) analysis of thermal power plants

AbstractThe growing energy supply, demand has created an interest towards the plant equipment efficiency and the optimization of existing thermal power plants. Also, a thermal power plant dependency on fossil fuel makes it a little bit difficult, because of environmental impacts has been always taken into consideration. At present, most of the power plants are going to be designed by the energetic performance criterion which is based on the first law of thermodynamics. Sometimes, the system energy balance is not sufficient for the possible finding of the system imperfections. Energy losses taking place in a system can be easily determined by using exergy analysis. Hence, it is a powerful tool for the measurement of energy quality, thereby helps to make complex thermodynamic systems more efficient. Nowadays, economic optimization of plant is also a big problem for researchers because of the complex nature. At a viewpoint of this, a comprehensive literature review over the years of energy, exergy, exergoeconomic and economic (4-E) analysis and their applications in thermal power plants stimulated by coal, gas, combined cycle and cogeneration system have been done thoroughly. This paper is addressed to those researchers who are doing their research work on 4-E analysis in various thermal power plants. If anyone extracts an idea for the development of the concept of 4-E analysis using this article, we will achieve our goal. This review also indicates the scope of future research in thermal power plants

Comparison of Power Distribution, Losses and Efficiencies of a Steam Turbine with and without Extractions

The paper presents an analysis of two steam turbine operation regimes - regime with all steam extractions opened (base process) and regime with all steam extractions closed. Closing of all steam extractions significantly increases turbine real developed power for 5215.88 kW and increases turbine energy and exergy losses with simultaneous decrease of turbine energy and exergy efficiencies for more than 2%. First extracted steam mass flow rate has a dominant influence on turbine power losses (in comparison to turbine maximum power when all of steam extractions are closed). Cumulative power losses caused by steam mass flow rate extractions are the highest in the fourth turbine segment and equal to 1687.82 kW

Energy and Exergy Investigations of a 972mw Based Steam Parameters Thermal Power Plant in Nigeria

The generation of electricity is critical to the expansion of the economy and the improvement of people's standard of living. Scientists from all over the world find themselves increasingly aware of the impact of power plants as a result of the expanding human population and the ever-increasing demand for dependable sources of energy. The construction of about 95% of power plants is carried out in accordance with energy performance requirements, which take into account only the first law of thermodynamics. It is not possible to use the first equation of thermodynamics to compute the actual effective energy loss since it does not differentiate between the quantity and quality of energy.Calculating energy and exergy based on the properties of the steam was at the focus of the investigation into the energy and exergy efficiency of the plant. According to the findings, an increase in the parameters governing the scalding steam caused an increase in both the system's efficiency and its enthalpy. The boiler has the highest exergy efficiency (59.66%), whereas the condenser has the highest energy efficiency (48.10%). The investigation proved beyond a shadow of a doubt that the boiler was the principal cause of the system's irreversibility. &nbsp

Thermodynamic and economic analysis of performance evaluation of all the thermal power plants : a review

Surging in energy demand makes it necessary to improve performance of plant equipment and optimize operation of thermal power plants. Inasmuch as thermal power plants depend on fossil fuels, their optimization can be challenging due to the environmental issues which must be considered. Nowadays, the vast majority of power plants are designed based on energetic performance obtained from first law of thermodynamic. In some cases, energy balance of a system is not appropriate tool to diagnose malfunctions of the system. Exergy analysis is a powerful method for determining the losses existing in a system. Since exergy analysis can evaluate quality of the energy, it enables designers to make intricate thermodynamic systems operates more efficiently. These days, power plant optimization based on economic criteria is a critical problem because of their complex structure. In this study, a comprehensive analysis including energy, exergy, economic (3-E) analyses, and their applications related to various thermal power plants are reviewed and scrutinized.The National Natural Science Foundation of China, Hubei Provincial Natural Science Foundation of China, Key Project of ESI Discipline Development of Wuhan University of Technology and the Scientific Research Foundation of Wuhan University of Technology.https://onlinelibrary.wiley.com/journal/20500505am2020Mechanical and Aeronautical Engineerin

Comparison of conventional and heat balance based energy analyses of steam turbine

This paper presents a comparison of conventional and heat balance based energy analyses of steam turbine. Both analyses are compared by using measured operating parameters from low power steam turbine exploitation. The major disadvantage of conventional steam turbine energy analysis is that extracted energy flow streams are not equal in real (polytropic) and ideal (isentropic) expansion processes, while the heat balance based energy analysis successfully resolved mentioned problem. Heat balance based energy analysis require an increase of steam mass flow rates extracted from the turbine in ideal (isentropic) expansion process to ensure always the same energy flow streams to all steam consumers. Increase in steam mass flow rate extracted through each turbine extraction (heat balance based energy analysis) result with a decrease in energy power losses and with an increase in energy efficiency of whole turbine and all of its cylinders (when compared to conventional analysis). All of the obtained conclusions in this research are valid not only for the analyzed low power steam turbine, but also for any other steam turbine with steam extractions

The Change in Low Power Steam Turbine Operating Parameters During Extractions Opening/Closing

The paper presents steam turbine power, energy and exergy efficiencies and losses analysis during steam extractions opening/closing. The analyzed steam turbine can be used in steam power plant or in the marine steam propulsion system (low-power steam turbine). Steam extractions opening and closing can have a notable influence on various turbine operating parameters, what is currently purely exploited in the literature. Turbine developed power during steam extractions opening/closing is direct proportional to turbine energy and exergy losses and reverse proportional to turbine exergy efficiencies. Turbine energy efficiency is not affected by steam extractions opening/closing. Considering all the combinations of turbine steam extractions opening/closing, it is obtained that the range of real developed power is between 30612.91 kW and 34289.14 kW, while the range of turbine exergy efficiencies is between 85.65% and 86.08%. The range of turbine energy power losses in all possible observed combinations is between 5401.78 kW and 6050.30 kW, while the range of exergy destruction is between 4949.44 kW and 5746.81 kW

Analysis and Comparison of Main Steam Turbines from Four Different Thermal Power Plants

This paper presents an analysis and comparison of four steam turbines and their cylinders from four different power plants (marine, conventional, ultra-supercritical and nuclear power plants). The main goal was to find which steam turbine and their cylinders show the best performances, the highest efficiencies, the lowest specific steam consumption and which turbine is the lowest influenced by the ambient temperature change. The highest efficiencies, both isentropic and exergy, are observed in the steam turbine and their cylinders from the ultra-supercritical power plant (whole turbine from ultra-supercritical power plant has an isentropic efficiency equal to 88.36% and exergy efficiency equal to 91.05%). Also, this turbine has the lowest specific steam consumption (7.32 kg/kWh) and exergy parameters of this turbine are the lowest influenced by the ambient temperature change. The worst performance (the lowest efficiencies, high specific steam consumption and the highest sensitivity to the ambient temperature change) show the cylinders and whole turbine from marine propulsion power plant. The same analysis and comparison are also performed for several other steam turbines from four mentioned power plants, so the presented relations and dominant conclusions have general validity. It can be concluded that steam turbines in ultra-supercritical power plants show the best performances in comparison to steam turbines from any other power plant

The influence of various optimization algorithms on nuclear power plant steam turbine exergy efficiency and destruction

This paper presents an exergy analysis of the whole turbine, turbine cylinders and cylinder parts in four different operating regimes. Analyzed turbine operates in nuclear power plant while three of four operating regimes are obtained by using optimization algorithms - SA (Simplex Algorithm), GA (Genetic Algorithm) and IGSA (Improved Genetic-Simplex Algorithm). IGSA operating regime gives the highest developed mechanical power of the whole turbine equal to 1022.48 MW, followed by GA (1020.06 MW) and SA (1017.16 MW), while in Original operating regime whole turbine develop mechanical power equal to 996.29 MW. In addition, IGSA causes the highest increase in developed mechanical power of almost all cylinders and cylinder parts in comparison to the Original operating regime. All observed optimization algorithms increases the exergy destruction of the whole turbine in comparison to Original operating regime - the lowest increase causes IGSA, followed by GA and finally SA. The highest exergy efficiency of the whole turbine, equal to 85.92% is obtained by IGSA, followed by GA (85.89%) and SA (85.82%), while the lowest exergy efficiency is obtained in Original operating regime (85.70%). Analyzed turbine, which operates by using wet steam is low influenced by the ambient temperature change. IGSA, which shows dominant performance in exergy analysis parameters of the analyzed turbine, in certain situations is overpowered by GA. Therefore, in optimization of steam turbine performance, IGSA and GA can be recommended.Comment: 25 pages, 10 figures, 4 table

ECOS 2012

The 8-volume set contains the Proceedings of the 25th ECOS 2012 International Conference, Perugia, Italy, June 26th to June 29th, 2012. ECOS is an acronym for Efficiency, Cost, Optimization and Simulation (of energy conversion systems and processes), summarizing the topics covered in ECOS: Thermodynamics, Heat and Mass Transfer, Exergy and Second Law Analysis, Process Integration and Heat Exchanger Networks, Fluid Dynamics and Power Plant Components, Fuel Cells, Simulation of Energy Conversion Systems, Renewable Energies, Thermo-Economic Analysis and Optimisation, Combustion, Chemical Reactors, Carbon Capture and Sequestration, Building/Urban/Complex Energy Systems, Water Desalination and Use of Water Resources, Energy Systems- Environmental and Sustainability Issues, System Operation/ Control/Diagnosis and Prognosis, Industrial Ecology