Measurement of Voidage of Sinter Ores in the Tubes

Abstract

An industrial vertical tank (cost $200,000) was produced to recover the heat of sinter ores in our laboratory, the voidage along the height direction needs to be studied in order to determine the best height of sintering layer in it. In this paper, the bulk bed voidage of sinter ores in cylindrical polyvinylchloride tube (PVC-U) was measured by the cross-section image analysis method. The large-diameter tube was used to minimize the wall effects so that we could measure the bulk bed voidage in the center of the tube. The results show that the new method is useful, the voidage increases at lower height and fluctuates slightly between 0.36 and 0.43 in a stable stage, the voidage increases as particle size increases, decreases as the shape factor increases, and increases as the tube to particle diameter ratios decreases. These provide significant voidage data for the study of a vertical tank.

Pressure drop in a packed bed with sintered ore particles as applied to sinter coolers with a novel vertically arranged design for waste heat recovery

“…D of the tube was 270 mm, which was comparable to those adopted by Zhang et al (2012) in their study to measure the packing voidage of SOPs.…”

“…The bed voidage for the unsorted case is almost identical to that for the size range of 30-40 mm, corresponding to an average equivalent particle diameter of 18.60 mm. Note that the bed voidage in this study is greater than the value of about 0.4 reported by Zhang et al (2012), although packed beds with comparable diameter and height and SOPs with similar sizes were adopted. The irregular shape of the SOPs is confirmed by the measured sphericity ranging from 0.62 to 0.66.…”

“…A novel design of sinter coolers featuring a vertical arrangement, resembling the coke dry quenching operation in vertical tanks, has been proposed in an effort to improve the waste heat recovery efficiency (Zhao et al, 2009), by taking advantage of the reduced air leakage in the more compact vertical tanks and more efficient heat transfer via countercurrent flow arrangement between the cooling air blowing upward and the SOPs that slowly drop down (Dong et al, 2012b). To better understand and optimize the operation of vertically arranged sinter coolers, issues regarding packing voidage (Zhang et al, 2012), pressure drop (Feng et al, 2014), and heat transfer (Dong and Li, 2011;Dong et al, 2012a;2014;Huang et al, 2015) have recently been addressed in available literature, with the packed layers of SOPs being treated as stationary packed beds for simplification, considering the low descending velocity (about 110 −3 m/s) of the SOPs in the vertical tanks (Feng et al, 2014).…”

Taguchi Orthogonal Test on Granule Properties and Porosity Distribution in Sintering Bed using High-resolution X-ray Computed Tomography

“…During the packing process, the iron ore granules at the lower part appeared certain of tamping caused by adhering layer deformation under the weight of granules above, 26) then fine granules in the upper part of the packed bed would fall down to occupy the voids in the lower part, which led to the denser packing at the lower part of the packed bed. 27,28) The porosity at the top and bottom of the packed bed exhibits a significant increase, which can be explained by wall effect, namely influenced by top and bottom wall of the container. Both topmost and bottommost granules of the packed bed were forced to form neatly arranged layers along the walls of top and bottom, and due to the point contact of granules with container wall, the porosity at the wall is higher than the other part of packed bed.…”

“…This finding agrees with the results observed from the S/N ratio analysis in Section 3.3. Studies have shown that the porosity fluctuation along packed bed height increases as the tube to granule diameter ratio decreases, 27) thus for a given container diameter, the larger granule size is, the greater axial porosity fluctuates. It can be concluded from the foregoing discussion that moisture is the dominant factor affecting granule size, and therefore contributes most to axial porosity segregation.…”