Rotor Design of Heavy-Duty Gas Turbines for Power Generation: A Comparative Analysis for Transition to Net Zero Emission Target

Abstract Current scenarios towards net zero emission assume an increasing demand for peaking operation of installed and new heavy-duty gas turbines for power generation, resulting in raising targets for transient behaviors of gas turbine rotors. During the design development process cyclic damaging mechanisms related to centrifugal and thermal loads, as well as rotordynamic effects leading to high vibration and associated high-cycle fatigue mechanisms are mandatorily considered, accounting for potential aging effects taking place during the engine life. Additionally, rotor deformation due centrifugal and thermal loads are analyzed in detail to achieve the best rotor-casing clearance conditions, aiming to maximize engine performance and availability. To satisfy the same set of functions and requirements different OEMs offer since decades alternative architectural layouts, stemming from both identified technical solutions and historical heritage. These existing layouts are compared in some publications, mostly focusing on baseload steady-state stress and idealized warm-up and cool-down considerations. In this paper the two main families of existing rotor designs, namely bolted and welded, are analyzed and compared, on the basis of two F-Class engines in the portfolio of Ansaldo Energia. With a specific attention to transient effects from real operating cycles relevant for flexibility demand, the paper shows insights about design, clearance, lifetime management and extension. The performed analysis highlights the key differentiators of the two fundamental rotor architectures that Ansaldo Energia is maintaining in its technology portfolio.