Abstract
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 is more than that of ACC based power plant with respect to CO2 emission. OCC plant emits about 0.164 kg/kWh of CO2 which is approximately 16.75 times lower than the CO2 emission in ACC based power plant. It is also analyzed that the performance of the CO2 Capture Unit (CCU) for the OCC based plant is about 3.65 times higher than the ACC based power plant due to higher concentration of CO2 (nearly 80.63%) in the flue gas emitting from OCC plant. The study also reveals that the auxiliary power consumption per kg of CO2 capture of the OCC based plant is about 0.142 kWh/kg, which is approximately 0.06 times lower than the ACC based plant. The higher performance of the OCC based power plant is found at lower value of flue gas recirculation due to the fact that reduction in exergy destruction at the mixing zone of the combustor is higher than the increase in exergy destruction of the heat exchangers at higher furnace exit temperature. But the metallurgical temperature limit of boiler tube materials restricts the use of the higher value of furnace temperature. OCC based power plant with CO2 capture can be preferred over ACC based plant with CO2 capture due to higher environmental benefits towards mitigating CO2, the key greenhouse gas on earth in spite of exhibiting lesser energy and exergy efficiencies.
Highlights
Mansouri and Mousavian (2012) showed that among the additional components of the retrofitted plant, the Air Separation Unit (ASU) and CCS have the largest amount of exergy destruction
It is analyzed that the gross energy efficiency of OxyCoal Combustion (OCC) based power plant without flue gas recirculation is higher than the Air-Coal Combustion (ACC) based power plant by about 0.415% point
The overall study concludes the following points: Air-Coal Combustion (ACC) based 500MW SupC steam power plant with CO2 capture is more energy and exergy efficient compared to Oxygen-Coal Combustion (OCC) based plant by about 6.44 % and 5.77 %- points, respectively
Summary
The growing demand for Power and Electricity reflects the development of any country. The above said reason is the main factor responsible for old coal-fired power plants having lower plant efficiencies in India. For meeting the growing challenges of energy requirement for developing countries like India, advanced power production technologies that can give better efficiencies is of high importance. For fulfilling the growing energy demand and safeguarding the environment, at Indian climatic conditions, the detailed thermodynamic study of the advanced power generation technologies is required. The main aim of the present work is to carry out a 3-E (Energy, Exergy, and Environment) analysis of ACC and OCC based 500 MWe Supercritical power plants by applying High Ash (HA) Indian coal as a primary fuel source with CO2 capture systems under Indian climatic conditions
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More From: International Journal of Mathematical, Engineering and Management Sciences
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