The purpose of the project is to obtain data for full-scale validation of predictive models for combustion and cocombustion of biomass in utility boilers. In addition, focus was on development of innovative optical measuring techniques as a means to increase data quality by fast measurements and to cut measurement costs. All measurements were carried out on a Mitsui-Babcock Low-NOx wall burner at Studstrup power plant, unit 4, Denmark in October and November 2009. Measurements on a pure coal (reference), coal-straw and coal-wood flame have been obtained. Special attention was paid to the coal-straw flame at conditions close to daily co-firing operation. 4 measurement ports was used for mapping of flames with a distance up to 6.72 m from burner wall using 5 m and 7 m long water-cooled probes. Gas temperatures and gas composition were measured by FTIR fibre-optic probe and extractive gas sampling for all type of flames. Additional, fast O2, NO and SO2 measurements using UV fibre-optic probe was performed in coal-straw flame. Particles were sampled for further analysis at selected positions with a special designed particle extraction probe to handle large straw particles. Axial and tangential velocities for coal-straw flame were mapped by Laser Doppler velocimetry (LDA) in 235 points. High speed IR-camera with water-cooled endoscope optics has been used to grab images of particle flow patterns and dispersion in flames. The IR-camera was also used with a grating spectrometer to measure gas and particle temperature with 1000 Hz. Al flames were highly turbulent and very large variations in temperature and gas concentrations are observed. Gas temperature profiles for all three flames become fairly similar 4 m away from burner wall, whereas large variations in gas composition profiles are found. LDA velocity measurements for the coal-straw flame show that the simple gas flow field expected for a single burner is smeared out shortly after start of flame due to interaction with other burners.
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Denmark. Forskningscenter Risoe. Risoe-r
Technical University of Denmark, Department of Chemical Engineering, 2011