Power generation gas turbine performance enhancement in hot ambient temperature conditions through axial compressor design optimization

Abstract

The output power and efficiency of gas turbines are profoundly influenced by ambient temperatures, with higher temperatures resulting in a notable decline in power output. This issue becomes particularly critical during periods of heightened power demand in hot climates. There are two common ways to solve this problem: incorporating auxiliary systems, such as inlet air cooling, or undertaking a comprehensive redesign of the gas turbine core engine. However, these methods sometimes are costly and unfeasible, particularly in regions characterized by arid conditions or constrained budgets for engine modifications. An alternative strategy has been developed to optimize axial compressor performance in order to improve gas turbine power in high-temperature environments, through an innovative approach. This approach centers on the concept of “re-staggering” the stator blades as a retrofit upgrade for existing gas turbines, enabling an increase in compressor inlet mass flow rate while maintaining peak efficiency at 45 °C. An in-house optimization tool was developed, incorporating a genetic algorithm and artificial neural network, to ascertain the optimal configuration of the re-stagger angles. This optimization process was initially coupled with a mean-line solver and subsequently refined using a through-flow model to enhance the preliminary design. The refined compressor design was then subjected to a comprehensive 3D Computational Fluid Dynamics analysis. Additionally, “end-bend” and “elliptical leading edge” techniques were employed to sustain compressor efficiency and ensure stability across various design and off-design operating conditions. Following a thorough structural analysis, the newly designed compressors were manufactured and tested at two distinct sites in Iran (Yazd and Bampur). The measured data demonstrated the commendable performance and stability of the redesigned compressors, aligning closely with numerical predictions. Notably, the results showcased a substantial increase in gas turbine power output ranging from 7.0% to 8.0% at hot ambient conditions, all while preserving efficiency and stability. Encouragingly, the upgraded compressor also exhibited superior performance even at lower temperatures, such as 15 °C. Consequently, this uprating concept presents a practical and cost-effective solution for power plant operators seeking a significant boost in power output, especially during hot weather conditions or in arid regions prone to drought.