Measurement of three-dimensional raceway structure in small scale cold model by X-ray computed tomography

Raceway zone in blast furnace is important region which closely relates to distributions of reducing gas and thermal energy, combustion efficiency of auxiliary reducing agents, degradation of coke particles, and so on. Although numerous works have been made on raceway phenomena, there still are ambiguities such as three-dimensional shape, structure, internal motion, etc.. This paper developed a new method to measure three-dimensional shape and structure of raceway by utilizing X-ray computed tomography. This method used differences between two successive CT images to distinguish regions with and without particle motion. The raceway shape was determined by the boundary of these regions. This method was applied to cold model experiments with alumina spheres of 3.2 mm in diameter. With this measurement, three-dimensional shape of the raceway was successfully revealed, and particles in the upstream region of tuyere actively moved. The results obtained by different measuring intervals show that the region in which the particles actively moved was surrounded by the region with relatively slow particle motion. It is expected that the discussion on the measuring interval and the particle size enables to classify spatially the raceway zone by the rapidity of particle motion.