This article presents a method for real-time simultaneous measurements of the temperature and soot volume fraction distribution of volatile matter flames, forming during combustion of biomass pellets. This method uses flame radiation spectra, captured by a spectrometer, and images, captured by a digital camera, as inputs during combustion of three different types of biomass pellets (pine wood, rice straw, and corn straw). The pellets were ignited and burned in the post-combustion zone of methane gas at 1300 K. The radiation spectrum of the flame in the 500−800 nm wavelength band was selected for spectral analysis, combined with a spectral emissivity model based on polynomial fitting. The flame emissivity was measured at the response wavelengths of a dual band-pass filter (centered at 615 and 517 nm) fitted on the camera, and the resulting emissivity ratio showed the degree of departure from the gray radiation model. The measured emissivity ratio approached unity as the combustion intensity increased. The emissivity ratio of the spectrometer measurement was used to correct the flame temperature measurement obtained by the image method. Upon correction, the maximum relative error of the image temperature measurement was determined to be 2.7% by comparison to thermocouple readings. The experimental results showed that the maximum flame temperatures of pine wood, rice straw, and corn straw pellets were remarkably similar at 1876 ± 2 K. Moreover, the flame burnout durations and the peak soot volume fractions were both positively correlated with the volatile content of biomass pellets; the value of the latter was 1.19 ± 3 ppm. The experimental results measured in this article can provide data for models of the soot generation mechanism of biomass pellet combustion in industrial furnaces.

This study describes experimental explorations on the effects of gas extraction on hydrodynamics in a pilot-scalegas fluidized bed membrane reactor (FBMR) at high temperatures. Differential pressure signals were measured at different vertical intervals in bed and were then characterized by multiscale resolution and power spectra analysis. The experimental results showed that the relative amplitude of σ r (σ/x av ) of pressure signal tended todecrease with the increase of gas extraction fraction.At room temperature, 20% gas extraction caused defluidization at an inlet velocity of 2U mf . However, athigh temperatures the gas extraction simultaneously decreased the magnitude of the low-frequency components and the numbers of the medium-to small-sized structures, mainly due to the decreased number of small-sized structures and the integration of bubbles. This effect of gas extraction increased with increase of gas extraction fraction and slightly decreased at higher inlet gas velocities. At elevated temperatures, the D6 sub-signals (0.781~1.562Hz) possessed the highest wavelet energy distribution percentage of the pressure signals, which meant that the medium-to small-sized bubbles dominated the gas-solid flow dynamics. Gas extraction was observed to enhance the dominance of the D6 scale components..