乾留過程におけるコークス層内熱応力の推算

Abstract

Fissures in the coke layer have a great influence on the coke qualities, for instance, its strength and size, and the production cost. It is well-known that the thermal stress caused by the drastic contraction in the coke layer would be the major cause of fissures. But few analytical studies have been carried out on the thermal stress in the coke layer. We have then tried to estimate the thermal stress distribution in the coke layer, using the finite element method. We have applied an incremental theory to our FEM formulation. As a result, we have obtained the following results.1. Comparing with x-ray photographs taken through the coking process, we find a good correspondence between the fissure formation behavior on the photograph and the estimated principal tensile stress distribution.2. With the increase of the heating rate on the wall, we estimate the greater principal tensile stress in the coke layer, which indicates that higher heating rates lead to more and greater fissures in the coke layer.3. The estimated results of the thermal stress distribution depend on temperature-dependencies of thermal property, contraction coefficient and Young's modulus.