Application of Optical Diagnostics Techniques to a Laboratory-Scale Turbulent Pulverized Coal Flame

Abstract

Combustion measurements based on optical diagnostics techniques, which allow noninvasive measurements of velocity, density, temperature, pressure, and species concentration, have recently become of major interest as tools not only for clarifying the combustion mechanism but also for validating the computational results for the combustion fields. In this study, the combustion characteristics of a pulverized coal flame are investigated using advanced optical diagnostics. A laboratory-scale pulverized coal combustion burner is specially fabricated. Velocity and shape of nonspherical pulverized coal particles, light emissions from a local point, and temperature in the flame are measured by shadow Doppler particle analyzer (SDPA), a specially designed receiving optics (multicolor integrated receiving optics, MICRO), and a two-color radiation pyrometer, respectively. The simultaneous measurement of OH planar laser-induced fluorescence (OH-PLIF) and Mie scattering image of pulverized coal particles is performed to examine spatial relation of combustion reaction zone and pulverized coal particle. The results show that the sizeclassified diameter and velocity of the pulverized coal particles in the flame can be measured well by SDPA. The measurements of the OH chemiluminescence and CH band light emission from a local point in the flame using MICRO and the simultaneous measurement of the instantaneous OH-PLIF and Mie scattering image of pulverized coal are effective for evaluating the pulverized coal flames and investigating their detailed flame structure.

Numerical analysis on effect of furnace scale on heat transfer mechanism of coal particles in pulverized coal combustion field

“…However, the thermal histories of coal particles in the experimental facilities can be different from that in the actual large scale boilers because the scale of flame can affect the heat transfer mechanism of the coal particles. Experimental apparatus with various sizes, e. g., the drop tube furnace (8-60 g-coal/h) [21,22], the small coal jet burner (0.5 kg-coal/h) [11,23], the triple stream burner (0.36-2.16 kg-coal/h) [24,25], the RWTH furnace (6-7 kg-coal/h) [26,27], the RWEn Combustion Test Facility (70 kg-coal/h) [28], the BEACH furnace (100 kg-coal/h) [13,29,30,31], the IFRF furnace No. 1 (260 kg-coal/h) [32] and the MARINE furnace (300 kg-coal/h) [19,33], have been used to investigate the coal combustion phenomena or to evaluate the combustion characteristics of various coal brands by some researchers.…”

Eulerian–Eulerian multi-fluid methods for pulverized coal flames with nongray radiation

“…Radiation also has indirect influence on CO 2 predictions through the slow yet strongly temperature-dependent char reaction rates. The consideration of radiation improves predictions of both temperature and CO 2 .…”

“…The target flame for validation purposes is a pulverized coal ignition jet flame piloted by a methane flame [2][3][4]. The fuel injector, as shown in Fig.…”

“…In the original flame measurements [2][3][4], the particle temperature was inferred from a two-color pyrometer operating at 0.9 and 1.0 lm. Such a pyrometer measures flame radiation at two wavelengths along line-of-sight.…”

“…The accuracy of a model set in a simulation is validated through the comparison of model predictions to experimental measurements. For example, the target flame of this study [2][3][4] investigated coal ignition processes in a methane pilot. An accurate simulation of coal flames demands a high-fidelity comprehensive approach to multiple physics, which include turbulence, multiphase flow, chemical reactions and heat transfer together with their interactions [1].…”