ARTICLE:

• Solid mass fluxes and local heat transfer to the walls in upper part of CFB riser  download article

Georgy A. Ryabov
All-Russian Thermal Engineering Institute, Avtozavodskay, 14/23, Moscow, Russia

Oleg M. Folomeev
All-Russian Thermal Engineering Institute, Avtozavodskay, 14/23, Moscow, Russia

Dmitry A. Shaposhnik
JSK "Belenergomash", Chmelnitskay, 111, Belgorod, Russia

ABSTRACT

The effect of the exit geometry on the flow pattern in a circulating fluidized bed (CFB) riser was studied in two cold models with cross-sectional areas of 0.4×0.4 m. and 0.7*0.7m. The upper parts of the risers were connected to a cyclone or U-beam collectors. Four rows of U-beam collector were installed external to the furnace with solids recycle through non-mechanical L-valve. Some experiments were carried out with two (one) rows in-furnace U-beams. The influence of gas velocity, furnace inventory, solids properties (mean diameter and density) were studied. Some data were also obtained on a small size high temperature CFB model (0.2×0.25 m). Several probes for in-situ measurements including suction sampling probe systems and a differential Doppler Anemometer with fiber optics were used. Local mass fluxes were determined in 40−60 different points on three (two) levels of the risers.
The goal of the investigation is to obtain new experimental data and correlations on the local solid fluxes in the exit region and data on superior solid collection efficiency of U-beams. "Collection efficiency" of exit region of the riser are obtained for different arrangements of this zone (cyclone, U-beam separator, internal U-beam). Data of solid collection efficiency of U-beam are compared with calculations using the two-dimensional mathematical model. Empirical correlations are developed to predict the internal circulation rate and "collection efficiency" of the exit region.

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