An Experimental Study of Lean Blowout With Hydrogen-Enriched Fuels

Abstract

premixed combustion is widely used to achieve a better compromise between nitric oxide (NOx) emissions and combustion efficiency (related to CO levels). However, com-bustor operation near the lean blowout (LBO) limit can render the flame unstable and lead to oscillations, flashback, or extinction, thereby limiting the potential range of lean combustion application. Recent interest in integrated gasification combined cycle plants and syngas combustion requires an improved understanding of the role of hydrogen on the combustion process. Therefore, in the present study, combustion of pure methane and blended methane-hydrogen with hydrogen-levels up to 80 % by volume has been con-ducted in a swirl stabilized premixed combustor. Particle imaging velocimetry (PIV) and OH * chemiluminescence imaging have been used in this study. Results show that there is a single-ringed structure of internal recirculation zone (IRZ) in the non-reacting flow, while in the reacting flows, there is a more complex flow pattern with a two-celled IRZ structure in which the axial velocity near the center-axis is oriented downstream. As the equivalence ratio decreases, the width of IRZ decreases in methane flames while it increases in hydrogen-enriched flames, and the flame shape changes from conical to an elongated columnar shape, especially in hydrogen-enriched flames. There are two differ-ent modes of vortex breakdown observed, spiral mode in methane flames and bubble mode in hydrogen-enriched flames. These differences between the behavior of the methane-only and hydrogen-enriched flames lead to different behavior of the flame as it approaches the lean blowout. The differences in the mechanisms of LBO in pure methane and hydrogen-enriched premixed flames are examined and explained in the present study. [DOI: 10.1115/1.4004742

Physical and Chemical Features of Hydrogen Combustion and their Influence on the Characteristics of Gas Turbine Combustion Chambers

“…The greatest effect was achieved with small additions of hydrogen (up to 12-20% [46] by mole fractions), while an increase to 29% by mole fractions, although it had a further positive effect on combustion stability, was not so pronounced. It was shown in [45] (Figure 22) that the addition of hydrogen to methane up to 20% by volume reduces the equivalence ratio during the blowout of a homogeneous flame by 9-10%, and the dependence of Φ blowout on the volume content of hydrogen in the fuel is linear, which is also confirmed in [43]. However, in [43], the effect of H2 on flame blowout is more significant and amounts to about 15-20% Φ for every 20% addition of hydrogen.…”

“…It was shown in [45] (Figure 22) that the addition of hydrogen to methane up to 20% by volume reduces the equivalence ratio during the blowout of a homogeneous flame by 9-10%, and the dependence of Φ blowout on the volume content of hydrogen in the fuel is linear, which is also confirmed in [43]. However, in [43], the effect of H2 on flame blowout is more significant and amounts to about 15-20% Φ for every 20% addition of hydrogen.…”

“…The reliability of the combustion chamber is determined by such characteristics as lean flame blowout, flashback and pulsating combustion. The addition of hydrogen to methane significantly increases the blowout limits of both suspended and attached diffusion flames [42,43] (Figure 20). The effect of adding hydrogen to the air flow is much more pronounced than that of adding it to methane (with separate fuel supply).…”

“…The addition of diluents (CO2 and N2) to the fuel reduced the resistance of the diffusion flame to a much greater extent for the suspended flame than for the attached flame. -Flame blowout during combustion of methane and hydrogen methane [42,43].…”

Feature-Parameter-Criterion for Predicting Lean Blowout Limit of Gas Turbine Combustor and Bluff Body Burner

“…On predicting lean blowout in gas turbine combustor, there are three main methods at present: experimental research method, empirical formula method, and numerical simulation method. In experimental research, Marinov et al [2,[10][11][12] and Yuan et al [13][14][15][16] did effective work in their respective fields. But the experimental research method needs high-precision measuring equipment and the cost is high.…”