THERMODYNAMIC AND ECONOMIC INVESTIGATION OF AN IMPROVED GRAZ CYCLE POWER PLANT FOR CO_2 CAPTURE

摘要

Introduction of closed cycle gas turbines with their capability of retaining combustion generated CO_2 can offer a valuable contribution to the Kyoto goal and to future power generation. Therefore research and development at Graz University of Technology since the 90's has lead to the Graz Cycle, a zero emission power cycle of highest efficiency. It burns fossil fuels with pure oxygen which enables the cost-effective separation of the combustion CO_2 by condensation. The efforts for the oxygen supply in an air separation plant are partly compensated by cycle efficiencies far higher than 60 %. In this work a further development, the S-Graz Cycle is presented, which works with a cycle fluid of high steam content. Thermodynamic investigations show efficiencies up to 70 % and a net efficiency of 60 % including the oxygen supply. For a 100 MW prototype plant the layout of the main turbo-machinery is performed to show the feasibility of all components. Finally, an economic analysis of a S-Graz Cycle power plant is performed showing very low CO_2 mitigation costs in the range of 10 $/ton CO_2 captured, making this zero emission power plant a promising technology in the. ease of a future CO_2 tax.