Axial sCO${}_2$ high-performance turbines parametric design

Highlights

• sCO${}_2$turbines are roughly one-fifth the size of steam turbines of the same shaft power.

• sCO${}_2$turbines achieve comparable efficiency to steam turbines.

• Over 460 high-performance axial sCO${}_2$turbines were optimized.

Abstract

Supercritical CO${}_2$ thermal cycles provide low complexity and small size of equipment compared to the Rankine cycle. However, higher power units of hundreds of megawatts have not yet been implemented. This study focuses on sCO${}_2$turbines for high power cycles and presents an estimation of their dimensions, efficiency, and other parameters. For this purpose, a specialized calculation code named TACOS was built. The turbines are designed for inlet pressures of 25 MPa and 30 MPa and inlet temperatures from 300 $°$C to 600 $°$C. In total, more than 460 high-performance axial turbines were designed in this study. The turbines have been optimized with shaft power from 10 MW to 2,000 MW (one-flow configuration) for revolutions from 3,000 rpm to 12,000 rpm. The results show that supercritical CO${}_2$ turbines are about one-fifth the size of their steam alternatives with comparable efficiencies. Turbines with synchronous revolutions (50 Hz) achieve the highest efficiency for shaft power in one-flow configuration up to 500 MW and this correspond to an efficiency close to 90%. High-speed turbines are suitable for power levels up to 50 MW with efficiencies of around 87%. The vast majority of turbines come out as three-stage or four-stage.