Advanced Gas Turbine Cooling for the Carbon-Neutral Era

Abstract

In the coming carbon-neutral era, industrial gas turbines (GT) will continue to play an important role as energy conversion equipment with high thermal efficiency and as stabilizers of the electric power grid. Because of the transition to a clean fuel, such as hydrogen or ammonia, the main modifications will lie with the combustor. It can be expected that small and medium-sized gas turbines will burn fewer inferior fuels, and the scope of cogeneration activities they are used for will be expanded. Industrial gas turbine cycles including CCGT appropriate for the carbon-neutral era are surveyed from the viewpoint of thermodynamics. The use of clean fuels and carbon capture and storage (CCS) will inevitably increase the unit cost of power generation. Therefore, the first objective is to present thermodynamic cycles that fulfil these requirements, as well as their verification tests. One conclusion is that it is necessary to realize the oxy-fuel cycle as a method to utilize carbon-heavy fuels and biomass and not generate NOx from hydrogen combustion at high temperatures. The second objective of the authors is to show the required morphology of the cooling structures in airfoils, which enable industrial gas turbines with a higher efficiency. In order to achieve this, a survey of the historical development of the existing cooling methods is presented first. CastCool® and wafer and diffusion bonding blades are discussed as turbine cooling technologies applicable to future GTs. Based on these, new designs already under development are shown. Most of the impetus comes from the development of aviation airfoils, which can be more readily applied to industrial gas turbines because the operation will become more similar. Double-wall cooling (DWC) blades can be considered for these future industrial gas turbines. It will be possible in the near future to fabricate the DWC structures desired by turbine cooling designers using additive manufacturing (AM). Another conclusion is that additively manufactured DWC is the best cooling technique for these future gas turbines. However, at present, research in this field and the data generated are scattered, and it is not yet possible for heat transfer designers to fabricate cooling structures with the desired accuracy.

How to Compute Whether Biomass Fuels Are Carbon Neutral

“…Given its immediate technological availability [1][2][3][4][5][6][7][8][9], biomass energy has been playing a key practical role for decades already, and was conceptually supported by the traditional assumption of its carbon neutrality: under sustainable conditions, carbon dioxide emitted during combustion was held to be equal to its absorption during plant growth [10][11][12][13][14][15][16][17]. However, in order to clarify conditions of carbon (C) neutrality quantitatively and more reliably [18][19][20][21][22][23][24][25][26][27][28][29][30][31], it became necessary to model the annual natural C cycle globally and to consider its changes as a result of steadily growing large-scale biomass strategies [32][33][34][35][36][37][38][39][40]. Because a recent publication [41] found much interest in readership, this article dwells still deeper into the dynamism of C flows and their alterations after biomass fuel extraction from the natural C cycle.…”

How to Compute Whether Biomass Fuels Are Carbon Neutral

“…From among the available energy-related strategies, and given its immediate technological availability [4][5][6][7][8][9][10][11][12], biomass energy has been playing a key practical role for decades already, and was conceptually supported by the traditional assumption of its carbon neutrality: under sustainable conditions, carbon dioxide emitted during combustion was held to be equal to its absorption during plant growth [13][14][15][16][17][18][19][20]. However, in order to clarify conditions of carbon (C) neutrality quantitatively and more reliably [21][22][23][24][25][26][27][28][29][30][31][32][33][34], it became necessary to model the annual natural C cycle globally and to consider its changes as a result of steadily growing large-scale biomass strategies [35][36][37][38][39][40][41][42][43]. Because a recent publication [44] found much interest in readership [45][46]…”

Detailed and simplified plasma models in combined-cycle magnetohydrodynamic power systems

“…The idea of MHD plasma power generation is not new and has been studied experimentally, analytically, or computationally for years (Blackman et al, 1961;Wright, 1963;Jones, 1985;Rosa et al, 1991;Borghi et al, 1992;Davidson, 2001;Panchenko, 2002;Kayukawa, 2004;Ishikwa et al, 2007;Sarkar, 2017). Despite this, the concept of plasma power plant has not been used practically at commercial levels because economically it is not favorable compared to other technologies of power plants that have comparable efficiency but with less initial and operational cost, such as combined cycle gas turbines (CCGT) power plants, whose LHV (lower heating value) efficiency can reach nearly 50% (Takeishi and Krewinkel, 2023). However, plasma generators still have advantages such as the lack of moving parts, and the potential of reducing particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NOx) compared to a coal power plant with air-firing.…”