A model of thermally induced strain development in coke oven walls during carbonization

During the carbonization of coal, the thermal conditions within the supporting coke oven walls vary substantially. This gives rise to a continually developing strain field within the walls which could cause cracks to occur in the refractory materials and, thus, shorten the operating life of the oven. Since a more precise knowledge of the location of high strain regions should help in improving the design of coke ovens, a mathematical study was initiated to identify the conditions under which high strain gradients are induced during carbonization. As such, this paper outlines the construction and application of a mathematical model to evaluate the strain distribution and its development in coke oven walls during carbonization. The model includes the influence of all the main thermal and physical properties of silica refractory bricks within a finite element formulation to evaluate the temperature and thermally induced strain distributions in a cross-section of a coke oven wall. The thermal strain field for a typical oven design is calculated at a number of stages throughout the carbonization cycle. The model results provide a clear picture of the nature of the thermal strain distribution and its development, highlighting three areas where the strain conditions in the wall will be most severe.