An Estimation of Thermal Stress within the Coal Briquette during Carbonization

A thermal stress analysis within a coal briquette is performed with various heating patterns in order to simultaneously make the reduction of heat consumption rate and the enhancement of formed coke quality. The single briquette is charged into the small oven, which is purged of air and filled with nitrogen gas. The oven is then placed in the X-ray CT equipment and heated by the prescribed heating pattern to continuously observe the crack formation behavior of the briquette. The thermal stress analysis model which previously developed by authors is used to estimate the stress distribution within the briquette in this study. The effects of creep characteristics of the plastic and semi-coke layer, dilatation of the plastic layer and the pyrolytic reaction fraction dependence of thermophysical properties are considered in this model. The calculated stress distribution and deformation behavior in the briquette are compared with experimental observation results by X-ray CT. The results show that the model used in this study can quantitatively predict the stress distribution within the briquette and the model is an effective tool to investigate the high performance formed coke making process.