Comprehensive Data Set of Single Particle Combustion under Oxy-fuel Conditions, Part I: Measurement Technique

ABSTRACT

An improved experimental methodology is presented that provides combustion data of single pulverized coal and biomass particles with a high level of detail. This is the first part of a two-article series. A stereoscopic imaging system based on four intensified CCD-cameras is calibrated for in-situ measurements of temperature, size, shape, and velocity of solid fuel particles in the diameter range of 30–300 µm. An elaborate approach for 3D shape reconstruction from orthogonal projections of single particles shows significantly improved accuracy, which is validated against particle samples being collected with a suction probe. The close-meshed combination of imaging pyrometry and shadowgraphy is a further novelty. The parallel application of both techniques provides results for both self-luminous “hot” (imaging pyrometry) and “cold” (shadowgraphy) particles. This enhances information on particle ignition (particles switch from cold to hot) and duration of char burn-out (particles switch from hot to cold). Selected experimental results are presented which demonstrate the informative power of data sets formed by this approach. Torrefied miscanthus is burned in a laminar flow reactor. The particle size and aspect ratio are evaluated for the in-situ measuring method as well as for the collected samples. The results show a good correlation between both analysis routines, indicating the progress in solid fuel characterization by the improved optical technique in combination with particle sampling.

KEYWORDS:

• Optical measurement
• single particle
• particle shape
• biomass
• coal

Acknowledgments

The authors thank the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Projektnummer 215035359 – TRR 129 for its support through CRC/Transregio 129 “Oxy-flame: development of methods and models to describe solid fuel reactions within an oxy-fuel atmosphere. ”Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) – Projektnummer 215035359 – TRR 129“.

Notes

¹ Note that the particle-particle distance should be sufficiently high to avoid influences of heat and mass exchange between particles (Köser et al. 2015), which would be counter-productive for the target of these measurements.

Additional information

Funding

This work was supported by the Deutsche Forschungsgemeinschaft [Projektnummer 215035359]. Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 215035359 - TRR 129.