Mechanism of coke deterioration by shear stress

Abstract

To clarify the generation behavior of fine coke by shear stress in the lower part of blast furnace, coke degradation behavior was investigated using the shear stress tester. Furthermore the theory of tribology was applied to estimate the resistance of wear. The main results obtained are as follows; 1) The generation rate of coke fine was basically proportional to sliding distance. Shear conditions (shear rate and vertical stress) had a great effect on coke deterioration behavior. 2) The coke fine ratio increased rapidly with the vertical pressure or the decrease of coke strength. It was assumed that plastic deformation of coke surface layer resulted in the expand of real contact area among lump coke. 3) The wear resistance of coke could be described by the specific wear rate and breaking energy which were approximately 0.1 kJ-1 and 200 kJ/kg respectively for normal metallurgical coke.