In the previous work

the multiperiod planning optimization model of the whole production process has been presented. Due to the high energy consumption characteristics of PVC produced by calcium carbide method

the piecewise linear model to approximate the nonlinear items in real process was introduced and a mixed integer linear programming (MILP) model was established. However

it is difficult to solve it due to the large scale and the complex nonconvexity. Thus

a hierarchical decomposition algorithm is proposed to accelerate the computation progress. The problem is divided into two levels

in the first level

the operating states of equipment are optimized

which would be the hard-to-solve binary variables in the plantwide planning model; in the second level

the determined binary variables are embedded into the plantwide planning model

and thus a reduced scale scheduling optimization is executed. A case study was provided to verify the effectiveness of the proposed algorithm. Computational results show that the proposed algorithm can accelerate the computation greatly and the production costs are close to or even better than those given in the previous work.