CREEP ANALYSIS OF LUMP COKE DEFORMATION-BEHAVIOR DURING COAL CARBONIZATION PROCESS

A thermal stress analysis model is developed to estimate the coal carbonization process within a coke oven chamber whose model includes the effect of viscoelasticity of the plastic and semi - coke layer, dilatation of the plastic layer and the pyrolytic reaction dependence of thermophysical properties. An experiment is also carried out to measure the coke displacement and to observe the coke deformation behavior in a laboratory-scale coke oven at various heating rates. The displacement calculated with fraction of pyrolytic reaction dependence of thermophysical properties is in better agreement with experimental data than that calculated with the temperature dependence as the heating rate increases. This result shows that the effect of heating history is an essential factor in the thermophysical characteristics of lump coke. The displacement estimated by the viscoelastic model agrees well with experimental results compared with that estimated by the elastic model. This means that the viscoelasticity has to be considered for accurate estimation of the coke deformation behavior. The estimated maximum principal stress within the lump coke at the constraint condition of upper wall side is then larger than that under the free dilatation condition. This result fits appropriately with experimental observation.