Digital holographic sizer for coal powder size distribution measurement: preliminary simulation and experiment

Abstract

On-line and continuous measurements of coal powder size distribution in coal-fired plants remain challenging. A coal powder size measurement system based on digital holography (DH) is developed. The effects of several factors, i.e. pixel size, recording distance, particle size, and concentration, on particle size measurement by the DH method are quantified by simulation, yielding the suitable pixel size, recording distance and particle concentration. The measurement system is implemented based on the simulation results and applied to measure particle size distribution of pulverized coal samples. Results show that the particles are clearly reconstructed from the hologram, and the measured size distributions agree well with those of the samples measured by laser particle size analyzer. This work shows that the digital holographic sizer has great potential in coal powder size distribution measurement in power plant pipes.

Recent advances and applications of digital holography in multiphase reactive/nonreactive flows: a review

“…As a versatile computational imaging technique with a simple optical configuration, DH is particularly useful for in situ characterization of burning particles in multiphase reactive flows. Recently, DH has been widely applied in the study of coal particle combustion [118,121,[164][165][166][167][168][169][170][171][172]. Trolinger et al [172] first used DH to observe coal particle combustion in three dimensions.…”

“…Zhang et al [20] demonstrated that the optimal performance of DH can be achieved when the recording distance is very close to the critical distance. Wu et al [164,166] studied the effect of recording distance on the measurement accuracy of particle size and depth using simulated holograms. This suggested that the minimum size error and depth position error could be obtained by using the critical recording distance.…”

“…Thus, it is more suitable to measure particle fields with a relatively higher concentration [11]. The effect of particle concentration on particle detection efficiency, particle sizing and localization has been extensively investigated with simulations and experiments [20,164,[185][186][187]. So far, DH has primarily been used to detect sparse particle fields in a volume.…”

Effective estimation model of coal dust characterization parameters with image sensing

“…The image-based methods for coal dust concentration measurement remain in their early stages [10,11], with much research focusing on segmenting different overlapped particles and concentration evaluation. Of these, particle detection models based on grey, morphological, and physical have proved the feasibility of image-based methods with a high accuracy, low cost, and strong operability.…”