On the temperature and emissivity of torrefied biomass and coal in group particle combustion

• Published in: Bioresource technology 2024-08, Vol.406, p.131040, Article 131040
• Main Authors: Yao, Yuan, Panahi, Aidin, Schiemann, Martin, Levendis, Yiannis A.
• Format: Article
• Language: English
• Subjects: Biomass; Coal; Emissivity; Group Particle Combustion; Hot Temperature; Particle Size; RGB; Spectrometry; Temperature
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131040

[Display omitted] •Group combustion of coal particles and torrefied biomass particles was examined.•Effective spectral emissivities (ελ) of streams of burning particles were measured.•Temperatures (T) of streams of burning particles were measured.•ελ and T of burning isolated particles or groups of particles were compared.•The importance of burning particles in flame radiation was demonstrated. This laboratory study reports results on the group particle combustion of pulverized bituminous coal and various types of torrefied biomass. Combustion of particle streams in a drop tube furnace in air was concurrently monitored by a spectrometer and an electronic camera to obtain spectral emissivities and temperatures. As particle number density (PND) increased, biomass particles became more prone than coal to group combustion. Spectral emissivities increased with increasing PND from 0.2 to 0.4 for coal and from 0.1 to 0.3 for biomass, in the wavelength domain of λ = 600–1000 nm. Emissivities changed little with wavelength, giving credence to the gray body assumption. Particle cloud temperatures were in the range of 1650–1900 K, depending on PND, type of fuel, and location in the cloud; temperatures decreased with increasing PND. The radiative heat of the particle laden flames was predominantly attributed to burning chars in the flames and it increased with increasing PND.