Particle velocity measurements in a circulating fluidized bed

Abstract

In recent years, circulating fluidized beds (CFBs) have been extensively employed in a variety of industrial applications related to coal combustion and gasification, solid waste incineration, catalytic cracking of oil, and so on. To accomplish successful and reliable operation of CFBs, a number of investigations pertaining to different hydrodynamic aspects have been undertaken. Many of these are referenced in the monograph of Basu and Fraser (1991), review of Horio (1991), and the article of Mahalingam and Kolar (1991). The gross hydrodynamic features of CFBs are generally understood, but the detailed structure is established only to a limited extent. Some advancements in this direction have been made in recent years by Yang et al. (1991), Horio et al. (1988), and others. Detailed researches in this direction have been made in recent years by Yang et al. (1991), Horio et al. (1988), and others. Detailed researches in this direction will considerably help in the optimum and economic designs of CFB boilers. To aid in this direction, the authors have measured the three-dimensional particle velocities in a square-section CFB cold model under certain operating conditions at ambient temperature and pressure. Particle turbulent intensities and bed cross-sectional averaged voidage along its height are alsomore » measured. A majority of the investigations have been conducted in circular cross-section CFBs, but industrial preference is for a square cross-section CFBs, but industrial preference is for a square cross-section boiler, and hence they have adopted this configuration in their present work. Their measurements, while confirming the core-annulus flow structure for CFBs, also provide a more comprehensive microscopic detail of particle velocities in the two regions, in addition to providing a basis for particle aggregation.« less