The mathematical model was developed for estimating the clearance between the wall of coke oven and the coke cake.The prediction model is based on the balance between the contraction force and the coking pressure. The clearance begins to generate when the contraction force exceeds the coking pressure in this model. Contraction force is calculated in consideration of the visco-elastic behaviour of the thermal shrinkage of the coke. Coking pressure is calculated considering the generation and the dispersion of the gas in the melting layer. The relaxation time of coke used in this model was obtained by load test applied dilatometer. The clearance was measured by laser sensor and internal gas pressure was measured at 1/4 width away from wall, in 40kg test oven. The clearance calculated during the coking process were in good agreement with the experimental results, which supports the validity of the mathematical model. The model enables us to quantitatively understand the effects of coal properties, such as mean reflectance and maximum fluidity on the clearance formation.
