Image Recognition Method for Defect on Coke with Low-quality Coal

Abstract

The image recognition method was proposed to quantify non-adhesion grain boundaries which were considered as a factor of coke strength besides pores, and the correlation between coke strength and the amount of defects evaluated by the method was investigated in comparison with the one by the marking method. Coke with low-quality coal was fractured by a diametral-compression test, and the fracture crosssections were observed by a scanning electron microscopy (SEM) and a 3D laser scanning microscope (LSM). The marking method and image recognition method were applied to SEM and LSM images, respectively. As a result, the fracture strength measured by the diametral-compression test was linearly decreased with an increase in blending ratio of low-quality coal. In the marking method, most non-adhesion grain boundaries were not detected up to 50% in the blending ratio, and the boundaries increased sharply from 50 to 100% in the blending ratio. On the other hand, in the recognition method, the defects which were composed of both pores and non-adhesion grain boundaries, increased linearly with the blending ratio, and the amount of defects corresponded to coke strength. Therefore, the image recognition method is expected as the quantification technique of defects decreasing coke strength.

Effect of Meso-scale Pore Structure on Coke Strength

“…The scale parameter means tensile strength, and coke strength can be evaluated by the scale parameter. The scale parameter of Coke B was the largest, and the others decreased on the order of Coke A, Coke C, and Saito et al 10) reported that the scale parameter of coke decreased with the increase in the blending ratio of the lowquality coal, the present experimental results correspond to the results of these previous studies. However, the present results are slightly different from those obtained from the previous studies because the strengths of Coke A and Coke C are almost the same.…”

“…However, the present results are slightly different from those obtained from the previous studies because the strengths of Coke A and Coke C are almost the same. In terms of the experimental condition, the entire bulk density of the coal particles was 800 dry-kg/m 3 in the experiments of Kanai et al 9) and Saito et al 10) , whereas that of Coke C is higher than that of Coke A in the current study. In general, when the bulk density is high, the coke strength would be sustained by the superior adhesion of caking coal and/or low-quality coal because the contact probability of the coal particles increases and/or the void among the coal particles decreases.…”

“…They described that the connected pores with low roundness of below 0.2 increased with the increase in the ratio of slightly caking coal, and the coke strength decreased. On the other hand, Kanai et al 9) and Saito et al 10) focused on the non-adhesion grain boundaries, and the fracture surfaces of coke produced from caking and low-quality coal were examined using a scanning electron microscope and a laser microscope, respectively. Kanai et al…”

Estimation of Material Constants of Hot Coke under Inert Atmosphere

“…1) Observation of polished coke surface with an optical microscopy has been used for evaluating the pore structure. 2,3) Kanai et al 4) and Saito et al 5) reported the laser microscopy-observation of a fracture surface of coke and, using obtained images, a method for quantitative evaluation of factors affecting the strength reduction. X-ray computed tomography (X-ray CT) is an emerging technology for observing three-dimensional pore structures.…”

End-to-end Billet Identification Number Recognition System

“…Recently, several studies have been conducted on computer vision systems for the factory automation in steel industry. [1][2][3][4][5][6] To achieve factory automation, it is important to develop a system that recognizes the steel product identification number, which is the analogue of a person's name, [7][8][9][10] as this should be managed and tracked for customized production. Among steel products, billets are considered in this study.…”