Multi-bifurcation behaviors of stability regimes in a centrally staged swirl burner

2021 ◽  
Vol 33 (9) ◽  
pp. 095121
Author(s):  
Xinyao Wang ◽  
Xiao Han ◽  
Heng Song ◽  
Dong Yang ◽  
Chih-Jen Sung
Keyword(s):  
2014 ◽  
Vol 161 (11) ◽  
pp. 2842-2848 ◽  
Author(s):  
Matthias Euler ◽  
Ruigang Zhou ◽  
Simone Hochgreb ◽  
Andreas Dreizler

Author(s):  
Dominik Ebi ◽  
Peter Jansohn

Abstract Operating stationary gas turbines on hydrogen-rich fuels offers a pathway to significantly reduce greenhouse gas emissions in the power generation sector. A key challenge in the design of lean-premixed burners, which are flexible in terms of the amount of hydrogen in the fuel across a wide range and still adhere to the required emissions levels, is to prevent flame flashback. However, systematic investigations on flashback at gas turbine relevant conditions to support combustor development are sparse. The current work addresses the need for an improved understanding with an experimental study on boundary layer flashback in a generic swirl burner up to 7.5 bar and 300° C preheat temperature. Methane-hydrogen-air flames with 50 to 85% hydrogen by volume were investigated. High-speed imaging was applied to reveal the flame propagation pathway during flashback events. Flashback limits are reported in terms of the equivalence ratio for a given pressure, preheat temperature, bulk flow velocity and hydrogen content. The wall temperature of the center body along which the flame propagated during flashback events has been controlled by an oil heating/cooling system. This way, the effect any of the control parameters, e.g. pressure, had on the flashback limit was de-coupled from the otherwise inherently associated change in heat load on the wall and thus change in wall temperature. The results show that the preheat temperature has a weaker effect on the flashback propensity than expected. Increasing the pressure from atmospheric conditions to 2.5 bar strongly increases the flashback risk, but hardly affects the flashback limit beyond 2.5 bar.


Author(s):  
Parisa Sayad ◽  
Alessandro Schönborn ◽  
Mao Li ◽  
Jens Klingmann

Flame flashback from the combustion chamber to the premixing section is a major operability issue when using high H2 content fuels in lean premixed combustors. Depending on the flow-field in the combustor, flashback can be triggered by different mechanisms. In this work, three flashback mechanisms of H2/CH4 mixtures were visualized in an atmospheric variable swirl burner using high speed OH* chemiluminescence imaging. The H2 mole fraction of the tested fuel mixtures varied between 0.1 and 0.9. The flow-field in the combustor was varied by changing the swirl number from 0.0 to 0.66 and the total air mass-flow rate from 75 to 200 SLPM (standard liters per minute). The following three types of flashback mechanism were observed: Flashback caused by combustion induced vortex breakdown occurred at swirl numbers ≥ 0.53 for all of the tested fuel mixtures. Flashback in the boundary layer and flashback due to autoignition were observed at low swirl numbers and low total air mass-flow rates. The temporal and spatial propagation of the flame in the optical section of the premixing tube during flashback was studied and flashback speed for different mechanisms was estimated. The flame propagation speed during flashback was significantly different for the different mechanisms.


Author(s):  
Alex Frank ◽  
Peter Therkelsen ◽  
Miguel Sierra Aznar ◽  
Vi H. Rapp ◽  
Robert K. Cheng ◽  
...  

About 75% of the electric power generated by centralized power plants feeds the energy needs from the residential and commercial sectors. These power plants waste about 67% of primary energy as heat emitting 2 billion tons of CO2 per year in the process (∼ 38% of total US CO2 generated per year) [1]. A study conducted by the United States Department of Energy indicated that developing small-scale combined heat and power systems to serve the commercial and residential sectors could have a significant impact on both energy savings and CO2 emissions. However, systems of this scale historically suffer from low efficiencies for a variety of reasons. From a combustion perspective, at these small scales, few systems can achieve the balance between low emissions and high efficiencies due in part to the increasing sensitivity of the system to hydrodynamic and heat transfer effects. Addressing the hydrodynamic impact, the effects of downscaling on the flowfield evolution were studied on the low swirl burner (LSB) to understand if it could be adapted to systems at smaller scales. Utilizing particle image velocimetry (PIV), three different swirlers were studied ranging from 12 mm to 25.4 mm representing an output range of less than 1 kW to over 23 kW. Results have shown that the small-scale burners tested exhibited similar flowfield characteristics to their larger-scale counterparts in the non-reacting cases studied. Utilizing this data, as a proof of concept, a 14 mm diameter LSB with an output of 3.33 kW was developed for use in microturbine operating on a recuperated Brayton cycle. Emissions results from this burner proved the feasibility of the system at sufficiently lean mixtures. Furthermore, integration of the newly developed LSB into a can style combustor for a microturbine application was successfully completed and comfortably meet the stringent emissions targets. While the analysis of the non-reacting cases was successful, the reacting cases were less conclusive and further investigation is required to gain an understanding of the flowfield evolution which is the subject of future work.


Fuel ◽  
2018 ◽  
Vol 231 ◽  
pp. 61-72 ◽  
Author(s):  
Sebastian Bürkle ◽  
Lukas Georg Becker ◽  
Andreas Dreizler ◽  
Steven Wagner

2013 ◽  
Vol 92 (1-2) ◽  
pp. 237-267 ◽  
Author(s):  
Artur Tyliszczak ◽  
Davide E. Cavaliere ◽  
Epaminondas Mastorakos
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document