Abstract
The diffusion of gaseous reactant in pores is one of the processes essentially influencing the rate of the solution loss reaction of lumpy coke, if the reaction proceeds by partial internal burning. Then, the effective diffusion coefficient of carbon dioxide in lumpy coke was estimated through analysing the over all rate of the reaction by the application of the rate equations for complete internal burning.
Concerning slab samples, the diffusibility, (De/D) of carbon dioxide was respectively evaluated to be 1.8×10-2 and 1.2×10-2 for conventional metallurgical coke and formed cokes which had the porosities being 0.52 and 0.33 respectively.
The characteristic size of crushed coke depended on the estimation standard used. For instance, the sphere-equivalent size differed considerably from the size defined as the ratio of volume to external surface area of a particle, owing to the irregular shape of the crushed materials. The value of the diffusibility obtained by the use of the sphere-equivalent size was 2 to 3 times that according to the other size estimation and was nearly constant at 3.2×10-2 regardless of temperature above 1000°C for both kinds of coke, while it decreased with increase of temperature above 1000°C according to the other estimation.
