Design Details of a 600 MW Graz Cycle Thermal Power Plant for CO2 Capture

Abstract

The high power highest efficiency zero-emission Graz Cycle plant of 400 MW was presented at ASME IGTI conference 2006 and at CIMAC conference 2007. In continuation of these works a raise of power output to 600 MW is presented and important design details are discussed.The cycle pressure ratio is increased from 40 to 50 bar by a half-speed stage connected via gears to the main compressor shaft allowing to keep the volume flow to the main compressors constant. The compressors are driven by the transonic compressor turbine stage. Mass flow to the compressors is increased by the factor of 1.27, density in blades of the main compressors is raised by the same factor. The turbine inlet temperature is raised to 1500°C together with the increase in the cycle pressure ratio, both are well accepted values in gas turbine technology today.Most important development problems have to be solved in designing the oxy-fuel burners. They are presented here in the form of coaxial jets of fuel (natural gas or coal gas alternatively) held together by a steam vortex providing coherent flow and flame is ignited by its strong suction. Combustion is finalized by the mixing with a counter-rotating outer vortex flow of working gas leading to a well defined position of vortex break down.The transonic stage of the compressor turbine is supplied with innovative steam cooling forming coherent layers outside of the blade shell of which stress deliberations will be presented.

A review of recent developments in carbon capture utilizing oxy-fuel combustion in conventional and ion transport membrane systems

“…Further, most of the components, except for the turbines, are standard power plant equipment and thus the component development can be focused on the unconventional high-pressure turbine operating with primarily CO 2 and H 2 O as the working fluid [26]. Though the developers of the cycle claim to have significant research experience pertaining to this novel turbine [29], the costs and implementation feasibility are still relatively unknown. Further, the Graz cycle requires O 2 production via a cryogenic air separation unit, implying higher capital costs compared with the AZEP [2].…”

“…Specifically, heat is added to the cycle at an overall high average temperature [26], resulting in low entropy transfer into the cycle and consequently a higher potential for work. Additionally, since the bottoming Rankine cycle pumps the H 2 O up to high pressure in the liquid form, the work requirements are relatively small [29]. Further, most of the components, except for the turbines, are standard power plant equipment and thus the component development can be focused on the unconventional high-pressure turbine operating with primarily CO 2 and H 2 O as the working fluid [26].…”

Energy Conversion Processes withCO2‐Separation Not Reducing Efficiency

“…Figure 21.6 shows such a cycle. Steam-CO 2 -turbines are also used in the Graz cycle (an oxyfuel process) [24], which also tries to improve efficiency but uses oxygen produced by air separation for the combustion, which consumes about 8 percentage points of the power produced.…”

Thermodynamic and Economic Evaluation of an IGCC Plant Based on the Graz Cycle for CO2 Capture

“…But whereas IGCC plants have already been operating world-wide for many years and demonstration plants with CO 2 capture are running, a Graz Cycle plant still needs further research and development work. The authors showed in their publications on the Graz Cycle the feasibility of all components [6][7][8][9][10][11][12][13] but the step towards a demonstration plant is still big. Gas turbine manufacturers have to be confident that a Graz Cycle plant is also an economically attractive solution which will be of interest for utilities before they start developing the new turbomachinery needed.…”

“…[5][6][7][8][9][10][11][12]. So at the ASME IGTI conference 2008 in Berlin a 600 MW plant with gas turbine inlet conditions of 50 bar and 1500°C was presented [13].…”