Stability and Flame Structure Analysis of a Semi-Industrial Swirl-Stabilized Oxy-Fuel Combustion Chamber System for Biomass

Dominik König (), Marcel Richter, Jochen Ströhle and Bernd Epple
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Dominik König: Insitute for Energy Systems and Technology, Technical University of Darmstadt, Otto Berndt Straße 2, 64287 Darmstadt, Germany
Marcel Richter: Insitute for Energy Systems and Technology, Technical University of Darmstadt, Otto Berndt Straße 2, 64287 Darmstadt, Germany
Jochen Ströhle: Insitute for Energy Systems and Technology, Technical University of Darmstadt, Otto Berndt Straße 2, 64287 Darmstadt, Germany
Bernd Epple: Insitute for Energy Systems and Technology, Technical University of Darmstadt, Otto Berndt Straße 2, 64287 Darmstadt, Germany

Energies, 2025, vol. 18, issue 6, 1-18

Abstract: Oxy-fuel combustion is a promising way to avoid process-based CO 2 emissions. In this paper, the operational range of a new semi-industrial oxy-fuel combustion chamber for pulverized biomass is analyzed. This approach is used to gain a deeper understanding of the combustion setup and to examine the differences between air and oxy-fuel combustion on an industrial scale. Both analyzed parameters—flame spread and temperature distribution—have a significant influence on heat transfer in commercial boilers. The stability of various operating conditions is assessed by monitoring the CO content in the flue gas via a gas analyzer unit. For stable operation using walnut shells as fuel in an air atmosphere, an overall air-to-fuel ratio of 1.57–1.75 and a local air-to-fuel ratio of 0.75–0.95 provide the most stable conditions. A high swirl number of 0.9 is found to be critical for stability, as the increased fuel momentum entering the combustion chamber promotes a fuel jet-dominated swirl flame. For the corresponding oxy-fuel combustion with the same volume flows and three different oxygen concentrations between 27% and 33%, stable combustion behavior is also observed. Using a camera setup to analyze flame shape and spread, it is observed that the flame formed with an oxygen content of 33% most closely resembles the flame shape achieved under air combustion conditions. However, the combustion temperatures most closely match those of the air operating condition when the oxygen content is 27%. Overall, it is shown that the approach for corresponding oxy-fuel conditions features similar flame shapes to oxy-fuel combustion with flue gas recirculation in a semi-industrial combustion chamber.

Keywords: swirl-stabilized flame; flue gas recirculation; flame imaging; stability analysis; semi-industrial pilot plant (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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