Multi-objective Scheduling and Optimization of a PVC Plant: A Batch Based Approach

The calcium carbide Polyvinyl chloride (PVC) production process has the characteristics of mass production equipment, frequent product switching, continuous and batch production at the same time. It is critical to schedule the PVC manufacturing process for the Optimization of Process Operation and Energy Consumption. In this paper, we propose an integrated modeling and optimization method for multi-objective scheduling based on batch approach to address the problems of large model size, high dimensionality and the risk of exponential explosion in the PVC scheduling process. Firstly, the hybrid time description method is applied, the scheduling of PVC production is divided into batch decision making process and batch scheduling process, and the batch and multi-objective scheduling model is established with the optimization goal of minimizing the maximum completion time and production cost. Then, the distribution estimation algorithm is applied to optimally solve the scheduling model. The comparative results show that the integrated batch and multi-objective scheduling model reduce the completion time and total cost compared with the classical optimization model, and the model complexity is lower, which verifies the applicability and effectiveness of the model in the actual PVC production scheduling problem.