Analysis of a cooling system of the ultra-supercritical coal-fired power unit integrated with CO2 capture (original) (raw)
Related papers
2020
Department of Mechanical Engineering, National Institute of Technology Durgapur, Durgapur-713 209, West Bengal, India Mejia Thermal Power Station, Damodar Valley Corporation, Mejia-722 183, Bankura, West Bengal, India E-mail: sujitkarmakar@yahoo.com <em>Manuscript received online 16 June 2020, revised and accepted 11 August 2020</em> A thermodynamic study is carried out on a 500MWe coal based supercritical thermal power plant (base plant) with MonoEthanolAmine (MEA) based CO<sub>2</sub> capture unit integrated with a Kalina Cycle (Low-grade energy cycle) setup for Combined Cooling and Power (CCP) generation using Indian High Ash (HA) coal as fuel, and the results are compared with an imported Low Ash (LA) coal. The modelling and simulation of the different plant configurations are done by using the simulation software "Cycle-Tempo". The base plant is integrated with the CO<sub>2</sub>capture unit working on MEA based post combustion carb...
Operation of conceptual A-USC power unit integrated with CO2 capture installation at part load
Journal of Power Technologies, 2013
The key aims in research and development in the coal-fired power sector are improving the efficiency of electricity generation and reducing CO 2 emissions. Modern power systems require power units to be able to work flexibly at part loads with high efficiency. This paper presents a conceptual 900 MW coal-fired power unit. The unit operates with advanced ultra-supercritical (A-USC) steam parameters 35 MPa/700 • C and at 49% net efficiency. Improved efficiency results in significantly reduced CO 2 emissions. Further emission reduction requires the integration of coal-fired power plants with CO 2 capture installation. A newly-built power plant offers the possibility of fully optimized integration to reduce efficiency loss, which is related to the post-combustion capture process. CO 2 capture by wet chemical absorption MEA can be characterized by three indicators: the demand for heat, electric power to drive auxiliary equipment and cooling. In order to calculate these indicators the capture process was modeled in Aspen Plus. Calculated indicators for nominal and part load operation were used to model an integrated power unit in Ebsilon Professional 10.0. The characteristics of operating a power unit integrated with CO 2 capture installation were determined.
2019
Supercritical CO2 cycles (sCO2) are recognized as a promising solution for the exploitation of different energy sources: from fossil fuel combustion and nuclear energy to solar energy and waste heat recovery. The large range of possible applications and the possible scarcity of water for sCO2 systems makes the use of direct air-cooled heat rejection units (HRU) of great interest. This paper deals with the numerical modelling, supported by experimental data provided by an HRU manufacturer, of a sCO2 system, equipped with a direct air-cooled HRU, exploiting a stream of 53 kg/s of flue gases at 550°C. The selected sCO2 cycle is a simple recuperative cycle, whose maximum/minimum pressure and maximum temperature are optimized in design conditions obtaining an overall recovery efficiency of 21.71%. The analysis of the system in off-design conditions is carried out for different ambient temperatures and the optimal HRU operational strategy is investigated considering the possibility of var...
Selection of the cooling system configuration for an ultra-critical coal-fired power plant
Energy Conversion and Management, 2013
The appropriate selection of the condenser pressure, apart from raising the live steam parameters, is a factor which could have a decisive impact on the improvement in the efficiency of the thermal cycle. The pressure value depends both on the parameters and configuration of the cooling system. The condenser cooling system configuration is particularly important in the case of newly designed high-capacity ultra-supercritical power plants. The presented study comprises a comparison of two variants of a cooling system for a 900 MW ultra-supercritical power unit. The serial and parallel configurations of the condenser are considered. A thermodynamic analysis which takes account of the exhaust loss of the LP turbine is performed. Additionally, an economic analysis based on the NPV method is conducted for all investigated cases.
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, 2015
In aim to reduce the greenhouse-gas emissions and improve the low-grade heat efficiency, a modified CCHP (combined cooling, heating, and power) system is proposed using supercritical CO 2. This cycle combines a Brayton cycle and a transcritical ejector refrigeration cycle by adding an extraction turbine. A mathematical model is developed to simulate the modified CCHP system. Parametric analysis and exergy analysis are conducted to investigate the effects of key thermodynamic parameters on the performance and exergy destruction. Due to the difficulties in the thermal efficiency evaluation for CCHP system, a more practical performance metric is introduced in order to quantify system performance. The results indicate that both higher extraction rate and extraction pressure are helpful to gain more refrigeration. For the conditions considered, the exergy efficiency of the modified CCHP with the extraction turbine is higher than that of the CCHP with the no-extraction turbine from 10.4% to 22.5%. Furthermore, there is a large increase in the turbine power output and the exergy efficiency with increased turbine inlet temperature. It reveals that a rise of heat source quality benefits the system performance.
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.