Thermodynamic Analysis of a 500MWe Coal-fired Supercritical Power Plant with CO2 Capture Integrated with Kalina Cycle for Combined Cooling and Power (original) (raw)
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Energy, 2018
The subject of this paper is analysis of the cooling system of a conceptual advanced ultra-supercritical coal-fired power unit integrated with a CO 2 capture and compression unit (CCU). The capture unit, based on wet chemical absorption using MEA (monoethanolamine), was modelled in Aspen PLUS. The obtained results were used in the power unit model developed in Ebsilon Professional. The aim of the calculations was to determine the cooling demand of the CCU and to define the impact of the integration on the power unit operation under nominal and variable ambient conditions. Performed analyses show that, in nominal conditions, CO 2 separation and compression involve an increase in the cooling demand by about 21%. In higher ambient temperatures it is not possible to keep the assumed cooling parameters in the CCU. One of the solutions, is an increase in the area of the heat exchangers. Obtained results showed, that the total surface of all heat exchangers in the CCU has to be increased by 77% (48e89% for individual coolers). The need to collect a considerable amount of extra heat results in a rise in the cooling water temperature and in higher pressure in the steam turbine condenser by 0.3 kPa.
Energy Procedia, 2013
Power generation efficiency penalty is the main concern about carbon capture technologies. Improvement of power plant efficiency due to higher steam condition is frequently foreseen to outbalance the carbon capture penalty. This work focuses on the conceptual design of two coal-fired power plants using CO 2 as working fluid: one with postcombustion MEA-based CO 2 capture and one with oxy-combustion CO 2 capture with cryogenic air separation. Two maximal supercritical CO 2 temperatures are investigated (620 and 700°C). The combination of a Brayton supercritical CO 2 power cycle, a coal boiler and a capture process allows significant increase of the overall plant efficiency. Both post-combustion and oxy-combustion capture processes lead to a very high overall plant efficiency: approximately 41.5% for a 620°C power cycle and 44.5% for a 700°C power cycle. Oxy-combustion seems best fitted for supercritical CO 2 Brayton cycle due to a simpler thermal integration and the CO 2 purification devices already integrated in the CO 2 processing unit. Main resulting technological challenges are the very large heat exchanger needed in the CO 2 cycle in order to achieve high power cycle efficiency and the development of supercritical CO 2 turbine significantly different than steam or gas turbine especially because of the very large effort on wheel and the small size of the equipment. Numerous technological developments on process component will be necessary and a representative CO 2 cycle pilot plant will be needed to assess CO 2 leakage, corrosion and flexibility issues.
Energy Conversion and Management, 2019
The integration of supercritical CO2 (SCO2) cycle instead of steam Rankine cycle may be a revolutionary technique to increase the efficiency of coal-fired power plants. To effectively extract exergy from the fluegas and convert exergy to power, the characteristics of hot end (heat reservoir) and cold end (heat sink) should be fully considered, and the system multi-parameters should be optimized. In this study, based on a benchmark coal-fired power plant integrated with a recompression SCO2 power cycle, quantitative efficiency enhancements of system improvements of the hot end and cold end for SCO2 power cycle are calculated and compared. The optimized efficiency of benchmark coal-fired plant integrated with recompression SCO2 power cycle is 45.43%. When the fluegas at the economizer outlet is effectively used, the power plant efficiency can be increased by 1.32%. With single and double reheats to decrease the heat transfer irreversibility of the hot end, the power plant efficiency can be increased by 1.77% and 2.24%, respectively. Cold end optimization with single intercooling and cold air preheating can increase the power plant efficiency by 0.32% and 0.33%, respectively. Finally, a simple structure system and a complex structure system are proposed. With optimal system parameters, the power plant efficiencies of the complex and simple systems are 49.32% and 48.52%, respectively.
A concept of coal-fired power plant built around a supercritical CO 2 Brayton power cycle and 90% post-combustion CO 2 capture have been designed. The power cycle has been adapted to the coal-fired boiler thermal output, this boiler has been roughly designed in order to assess the power cycle pressure drop and its cost, an adapted CO 2 capture process has been designed and finally the overall heat integration of the power plant has been proposed. Due to the high complexity of such as plant, this paper does not intend to provide definitive evaluation of the concept but to explore its potential. A coal power plant with CO 2 power cycle without carbon capture could achieve a net efficiency of 50% (LHV) with a maximal temperature and pressure of 620 C and 300 bar, these performances has to be validated but the first results on pilot plant are encouraging. The CO 2 capture process use mono-ethanolamine as solvent and is equipped with vapor recompression systems in order to reduce the heat needed from the CO 2 cycle. It achieves around 2.2 GJ/t CO2 of specific boiler duty with 145 kWh/t CO2 of electrical auxiliary consumption including compression to 110 bar. The energetic evaluation of the overall power plant carried out highlights the promising potential of CO 2 supercritical cycle. A net power plant efficiency of 41.3% (LHV), with carbon capture and CO 2 compression to 110 bar, seem to be achievable with available or close-to-available equipment. A technical-economic evaluation of the designed power plant has been performed. It shows a levelized cost of electricity reduction of 15%, and a cost of avoided CO 2 reduction of 45%, without transport and storage, compared to a reference supercritical coal-fired power plant equipped with standard carbon capture process.
Sustainability
This article presents the performance analysis of a 700 MW future planned advanced ultra-supercritical (A-USC) coal-fired power plant fitted with post-combustion carbon capture and storage (CCS) technology. The reference A-USC unit without CCS achieves a net efficiency of 47.6% with CO2 emissions of 700 kgCO2/MWh. Relatively to subcritical units, the net efficiency of the A-USC is 8%-pts higher while CO2 emissions are 16.5% lower. For a CO2 removal rate of 90%, the net efficiency of the CCS integrated A-USC unit is 36.8%. The resulting net efficiency loss is 10.8%-pts and the electricity output penalty is 362.3 kWhel/tCO2 for present state CCS technology. The study continues with the assessment of interface quantities between the capture unit and the steam cycle affecting the performance of the A-USC. Improved CO2 absorbents could alleviate the net efficiency loss by 2–3%-pts, and enhanced CO2 compression strategies and advanced heat integration could further reduce the efficiency l...
Energy, 2019
Power generation from coal-fired power plants represents a major source of CO2 emission into the atmosphere. Efficiency improvement and integration of carbon capture and storage (CCS) facilities have been recommended for reducing the amount of CO2 emissions. The focus of this work was to evaluate the thermodynamic performance of s-CO2 Brayton cycles coupled to coal-fired furnace and integrated with 90% post-combustion CO2 capture. The modification of the s-CO2 power plant for effective utilisation of the sensible heat in the flue gas was examined. Three bottoming s-CO2 cycle layouts were investigated, which included a newly proposed single recuperator recompression cycle. The performances of the coal-fired s-CO2 power plant with and without carbon capture were compared. Results for a 290 bar and 593 0 C power cycle without CO2 capture showed that the configuration with single recuperator recompression cycle as bottoming cycle has the highest plant net efficiency of 42.96% (Higher Heating Value). Without CO2 capture, the efficiencies of the coal-fired s-CO2 cycle plants were about 3.34-3.86% higher than the steam plant and about 0.68-1.31% higher with CO2 capture. The findings so far underscored the promising potential of cascaded s-CO2 power cycles for coal-fired power plant application.
Thermodynamic Analysis of a Thermal Cycle of Supercritical Power Plant
The study presented in this paper deals with the analysis of operating conditions of a modern supercritical power plant. The 460 MW reference thermal cycle, which is based on the Lagisza supercritical, coal fired power plant was selected for this study. The thermodynamic analysis was performed with the use of the industrial software package IPSEpro, designed for power plant engineering. The main objective was to demonstrate the role of supercritical parameters in enhancing the efficiency of the thermodynamic process. It was done among the others by the comparative analysis of two thermal cycles, one working with standard and the other with supercritical parameters. Apart from nominal operating conditions part load operation was analyzed.
Assessment of carbon capture thermodynamic limitation on coal-fired power plant efficiency
The most mature CO 2 carbon capture process comes with a 12–10% pts efficiency loss when coupled with a coal-fired power plant and for both post and oxy-combustion. Pre-combustion induces less efficiency loss but at the cost of a more complicated overall process. Since the last decade numerous improvements have been made and this work tries to evaluate the thermodynamic minimum impact of CO 2 capture processes on such coal power plants. After detailing the calculation hypothesis, the purely thermodynamic impact has been assessed: they are 3.2% pt for post-combustion divided into 40% for separation and 60% for compression, 4.2% for pre-combustion especially due to CO-shift (60%), the rest evenly divided between separation and compression and 2.9% for oxy-combustion divided into one third for O 2 production and two thirds for compression and with a small efficiency gain compared to aero-combustion due to the reduction in flue gas volume. In the second part of this work, the realistic minimum energy consumption is assessed with some assumptions about compressor and pump efficiency, temperature pinch and overall process conditions. This study shows a 6.8% pt loss of efficiency for MEA absorption post-combustion process combined with classical compression train, 5.8% pt for a cryogenic post-combustion process, 6.6% pt for a MDEA absorption pre-combustion process with classical compression train, 5.4% pt for the cryogenic ASU oxy-combustion with standard cryogenic CPU. These realistic minimal impacts of CO 2 capture on supercritical coal power plants highlight the difficulty in designing a process with less than 5% pt of efficiency loss which is the main technological challenge of the CO 2 capture field at the moment. The better performance achievable seems around 6.0% pt loss of efficiency with good integrated low regeneration duty solvent for post-combustion or highly efficient ASU and CPU for oxy-combustion. However, a power plant practical efficiency of more than 40% is readily achievable with a well designed IGCC plant and, in near future, with USCPC power plant.
International Journal of Mathematical, Engineering and Management Sciences
The comparative performance study is carried out for 500 MW Supercritical (SupC) Oxy-Coal Combustion (OCC) and Air-Coal Combustion (ACC) power plants with membrane-based CO2 capture at the fixed furnace temperature. The proposed configurations are modelled using a computer-based analysis software 'Cycle-Tempo' at different operating conditions, and the detailed thermodynamic study is done by considering Energy, Exergy, and Environmental (3-E) analysis. The result shows that the net energy and exergy efficiencies of ACC power plants with CO2 capture are about 35.07 % and 30.88 %, respectively, which are about 6.44 % and 5.77 % points, respectively higher than that of OCC power plant. Auxiliary power consumption of OCC based power plant is almost 1.97 times more than that of the ACC based plant due to huge energy utilization in the Air Separation Unit (ASU) of OCC plant which leads to performance reduction in OCC plant. However, environmental benefit of OCC based power plant i...