Development of the Dense Pack Steam Turbine: A New Design Methodology for Increased Efficiency

摘要

Deregulation and increasing demand are creating rapid changes in the global energy market, placing a new premium on efficiency and creating the opportunity to structure new products for the evolving needs. To meet these needs through highly-efficient steam turbines, a new design methodology has been developed that is suitable for smaller combined cycle units and larger fossil-fired utility machines. A summary of that development process is given here. Drawing on technology from gas turbine and aircraft engine development, the new design has higher reaction, lower diameters, longer blades, and icnreased annulus area. I naddition, the stage count has been increased, generally without increasing the overall length of the machine, giving rise to the name "Dense Pack". These changes lead to a significant reduction in flow-through velocity velocity with a corresponding drop in profile losses, while the improved blade aspect ratio reduces the overall secondary losses. The lower velocities drive lower diameters, which are made possible by advances in rotordynamics technology. Developments in aerodynamics, manufacturing processes, advanced seals, and leakage flow control also increase efficiency.