Effect of Meso-scale Pore Structure on Coke Strength

Abstract

To explore the factors that affect coke strength in the meso-scale pore structure of coke, we investigated the relationship between the strength and meso-scale pore structure of the polished surface of coke sample. Coke was fractured using diametral-compression tests, and the tensile strength of coke was measured. Furthermore, we observed the polished surface of coke and obtained combined images with a size of 10 mm × 10 mm. The size and roundness of the pores were evaluated by image analysis. The pores were classified according to the pore size, and the strength of coke with many pores with a diameter of more than 1000 µm was indicated to be low. Moreover, the roundness of pores with a diameter of more than 1000 µm was low. Therefore, pores with diameter of more than 1000 µm and low roundness are considered to greatly affect the strength of coke in a meso-scale structure.

Pore Structure and Integrity of a Bio-Coke under Simulated Blast Furnace Conditions

“… where σ is the coke tensile strength; K 1c is the coke microstrength; P is the coke total porosity; P ′ is the porosity of connected pores, which is represented by the area fraction of pores with low roundness; a – e are constants; and ( P – P ′) represents the porosity of individual pores. It is generally accepted that the coke strength is significantly affected by pores with low roundness. ,, Kubota et al studied the pore structure using image analysis; they classified the pores with roundness below 0.2 as the pores with connected structure and considered such pores as the origin of defects and fracture under load. The porosity of connected pore in this study was calculated as the area fraction of pore with roundness lower than 0.2.…”

Numerical Investigation for the Temperature Dependency of Coke Degradation by CO₂ Gasification Reaction in a Blast Furnace

“…In previous studies, the dominant factor of the coke strength was largely distinguished to a strength of coke matrix and a pore structure, and it was especially found that the effect of pore structure was large. [1][2][3][4][5] The pore structure was subdivided to the shape of a pore, porosity and the others, and the subdivided factors has been investigated respectively. As the research focusing on the shape, Kubota et al reported the perimeter of a pore with low circularity in a coke sample and its strength had a negative correlation through the drum strength test of the sample and the observation of the cross section of the sample by an optical Numerical Investigation for the Temperature Dependency of Coke Degradation by CO 2 Gasification Reaction in a Blast Furnace microscope.…”

“…5) Saito et al also focused on the size of pore and its circularity and indicated that the strength of the coke with many pores with the size of 1 000 mm and low circularity was low. 1) From these studies, it was found that one of the dominant factors of coke strength is its pore structure.…”

Effect of Volatile Matter and Thermoplastic Components on Softening and Swelling Behavior in Carbonization of Coal

“…Many studies of coke have been conducted to correlate coke strength with pore structure. In the previous study, although those studies investigated characteristic of microscopic structures and origins of the fracture of coke which affect coke strength, [2][3][4] their objects were fabricated coke, and little is known about dominant factors in the formation of pore structure during coal carbonization. 5) As a study on a packed bed of coal during carbonization, Hays et al 6) carbonized a packed bed of coal in a furnace, in which one side of wall was heated, and samples were obtained with temperature gradient inside them.…”