Browsing by Author "Yang, Won"

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    Burning characteristics of single particles of coal and wood mixtures for co-firing in an upward-flowing hot gas stream
    (Elsevier, 2017-04-14) Mock, Chinsung; Lee, Hookyung; Choi, Sangmin; Yang, Won; Manovic, Vasilije
    This study presents the comparative burning behaviours of single solid particles of coal and biomass mixtures for co-firing. In this experimental investigation, a direct observation approach was used to investigate the ignition, flame characteristics and combustion times by means of high-speed photography at 7000 frames per second. Single particles were entrained into a hot gas stream at 1340 K and a rapid heating rate of 104–105 K/s. The apparent volatile flames from the prepared particle size groups were observed within 20–50 ms. To assess the effect of oxygen concentration, particles were burned for their flame characteristics in a range of 10%–40% O2. The test particles were sieved into three size groups (215–255 μm, 255–300 μm and 300–350 μm) to assess the effect of particle size. Special particles for the co-firing effect were collected individually from two types of mixed pellet: 20:80 and 50:50 coal/wood. Pure sub-bituminous coal and wood particles were also prepared in order to compare their combustion behaviours. In the experimental setup with a cross-injection configuration, sequential combustion processes were effectively and clearly described in terms of particle displacement with time. The experimental results showed distinguishable flame characteristics from single particles of coal, 50:50 coal/wood, 20:80 coal/wood and wood, including soot flame size and intensity. The impact of high coal-blending ratio caused an increase in the flame size and intensity and the ignition time was close to that of pure coal particles. Quantitative measurements of combustion events on co-firing particles were also discussed in relation to significant impacts of the particle size and the oxygen concentration.
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    Combustion behaviour of single pellets of coal–wood mixtures in a hot gas flow field
    (2018-09-21) Mock, Chinsung; Lee, Hookyung; Choi, Seuk-Cheun; Yang, Won; Choi, Sangmin; Manovic, Vasilije
    This experimental study explores the burning characteristics of single pellets made of wood and coal mixtures for co-firing. Three types of pellets were prepared with different wood–coal ratios (100:0, 80:20, and 50:50). Experiments were carried out in a laboratory reactor at rapid heating rates and under oxygen concentrations between 10 and 40%. To investigate their combustion behavior, single pellets were suspended on a wire injected into a hot gas stream at 1340 K and flame and char combustion were recorded through an observation window by means of a high-resolution (4K) camera. The sequential combustion time, volatile flame characteristics, and mass reduction rate were obtained over a time profile by carefully controlled particle injection. The results demonstrated that the char combustion time increased significantly in comparison to the volatile combustion time, which only varied a little, when the pellets contained coal in the mixture. Partially detached flames were also predominantly observed on pure biomass pellets at oxygen concentrations between 21 and 40%. During the homogeneous combustion period, the cross-sectional area of a pellet shrunk by 26.3–37.5% depending upon the type of pellet.