2020 Volume 60 Issue 6 Pages 1213-1224
Considering the “furnace-caster matching” modes, this paper focuses on the scheduling problems from practical steelmaking-continuous casting production lacking refining span. Aiming at the improvement on quality and output of steel products, a mathematical model is established with multi-objective optimization including the minimum earliness/tardiness of starting cast times, the shortest waiting times of heats among different processes and the shortest idle times of converters. A heuristic algorithm based on the optimization of “furnace-caster matching” mode is developed to solve this model, which involves two procedures of device assignment and conflict elimination. Through the detailed analysis on workshop layout and production rhythm, four classes of matching modes of “refining furnace-caster” are proposed to perform the assignments of refining furnaces. The assignments of converters rely on three categories of greedy strategies in terms of minimizing conflictions among heats. A rough scheduling solution with some possible conflicts among heats is obtained through combining “furnace-caster matching” modes and greedy strategies. Then applying the linear programming method to eliminate the conflicts and generate the final solution. Based on the proposed algorithm and the improved genetic algorithms, simulation experiments are carried out by introducing actual production plans as instances. The results indicate that heuristic algorithm based on the optimization of “furnace-caster matching” mode is the right candidate owing to its acceptable scheduling solutions with the better process matching relations and the highlighted performances under crane constraint. Currently, the proposed model and algorithm have been successfully used in a large converter steel plant in China.