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Development of hydrogen and micromix combustor for small and medium size gas turbine of Kawasaki
(2024)
Kawasaki (KHI) has made various improvements and commercialized hydrogen gas turbines for existing diffusion combustors (0–100 vol.% H2, wet combustion) and lean pre-mixed DLE combustors (0–30 vol.% H2). However, it is challenging for conventional combustion technology to achieve dry low NOx emissions for 100 vol.% hydrogen. Kawasaki’s unique approach is the development of a new dry combustion technology for high hydrogen content fuel: the micromix (MMX) combustion. Kawasaki established this combustion technology to achieve low NOx for 100 vol.% hydrogen combustion. Micromix is based on a large number of miniaturized non-premixed-type flames, making this concept inherently safe toward flashback. Recently, Kawasaki has commercialized a gas turbine with a micromix combustor as the world’s first dry gas turbine capable for 100 vol.% hydrogen. This paper shows the latest improvements of the micromix combustor before the commercialization with focus on NOx reduction achieved by decreasing the fuel injection hole diameter, and the extension of the operational flexibility by applying a supplemental burner system. During demonstration tests with a 1.8 MWel gas turbine, it could be proven that this novel combustion concept meets Japan’s fundamental NOx regulations (84 ppm referred to 15 vol.% residual O2) for pure hydrogen and furthermore can be operated with natural gas/hydrogen blends in the range up to 50 vol.% H2 over the entire load range.
Analyse der Temperatur- und Strömungsungleichförmigkeiten in mehrstufigen Turbinen / Harald Funke
(2001)
With the final objective of optimizing the "Micromix" hydrogen combustion principle, a round jet in a laminar cross-flow prior to its combustion is investigated experimentally using Stereoscopic Particle Image Velocimetry. Measurements are performed at a jet to cross-stream momentum ratio of 1 and a Reynolds number, based on the jet diameter and jet velocity, of 1600. The suitability to combine side, top and end views is analyzed statistically. The statistical theory of testing hypotheses, pertaining to the joint distribution of the averaged velocity along intersecting observation planes, is employed. Overall, the averaged velocity fields of the varying observation planes feature homogeneity at a 0.05 significance level. Minor discrepancies are related to the given experimental conditions. By use of image maps, averaged and instantaneous velocity fields, an attempt is made to elucidate the flow physics and a kinematically consistent vortex model is proposed. In the time-averaged flow field, the principal vortical systems were identified and the associated mixing visualized. The jet trajectory and physical dimensions scale with the momentum ratio times the jet diameter. The jet/cross-flow mixture converging upon the span-wise centre-line, the lifting action of the Counter Rotating Vortex Pair and the reversed flow region contribute to the high entrainment and mixedness. It is shown that the jet width is larger on the downstream side as compared to the upstream side of the centre-streamline. The deepest penetration of the particles on the outer boundary occurs in the centre-plane. Meanwhile, with increasing off-centre position, the boundaries all lay further from the centre-line position than does the boundary in the centre-plane, corresponding to a kidney-like shape of the flow cross-section. The generation of the Counter Rotating Vortex Pair and the instability mechanism is documented by instantaneous image maps and vector fields. The necessary circulation for the Counter Rotating Vortex Pair originates from a combined effect of steady in-hole, hanging and wake vortices. The strong cross-flow and jet interaction induces a three-dimensional waving, the stream-wise Counter Rotating Vortex Pair pair, leading to the formation of Ring Like Vortices. A secondary Counter Rotating Vortex Pair forms on top of the primary Counter Rotating Vortex Pair, resulting in mixing by "puffs". Overall, Stereoscopic Particle Image Velocimetry proofed capable of elucidating the Jet in Cross-Flow complex flow field. The gained insight in the mixing process will definitely contribute to the "Micromix" hydrogen combustion optimization.
