Deterioration of Coke Strength by CO₂ Gasification at High Temperature

Abstract

The deterioration of coke in the blast furnace has been evaluated as the change in coke size due to reaction between coke and CO₂ gas. To clarify the deterioration mechanism, a series of experiment has been carried out at each reaction temperature using apparatus for high temperature CO₂ reaction.
The findings obtained are as follows :
(1) The deterioration of coke by CO₂ gasification reaction was largely changed with the temperature for CO₂ reaction.
(2) Reaction up to 1300°C : Due to the selective reaction by the anisotropic texture of coke, reaction proceeded to the central core of the lump and weight loss affected the decrease of coke strength.
(3) Reaction between 1300°C and 1500°C : Coke lump reacted uniformly on its surface, thereby holding very low reaction rate in the core of the coke lump. Weight loss did not affect the decrease of coke strength.
(4) As CO₂ reaction below 1300°C decreased remarkably the coke strength, if weight loss caused by the reaction lower than 1300°C could be decreased, this countermeasure would become an important method for the control of coke deterioration.
(5) A good quality coke at high temperature showed uniform microstructure and high reactivity with CO₂ gas at pore-wall.