AN IMPROVED CONTINUOUS-TIME FORMULATION FOR SHORT-TERM SCHEDULING WITH RESOURCE CONSTRAINTS

An enhanced continuous-time formulation is presented for the short-term scheduling of multipurpose batch plants with intermediate due dates and a variety of resource constraints. The proposed formulation is based on the continuous-time formulation presented by Ierapetritou and Floudas (1998) and incorporates several features that include: (i) various storage policies (UIS, FIS, NIS, ZW), (ii) resource constraints, (iii) batch mixing and splitting, and (iv) sequence-dependent changeover times. The key features of the proposed formulation include a continuous-time representation utilizing a necessary number of event points of unknown location corresponding to the activation of a task. Also, tasks are allowed to continue over several event points enabling resource quantities to be correctly determined at the beginning of each resource utilization. An example problem is presented to demonstrate the effectiveness of the proposed approach. The computational results are compared with those in the literature and it is shown that the proposed formulation is significantly faster than other general resource constrained models, especially for problems requiring many event points.

[1]  Christodoulos A. Floudas,et al.  Enhanced Continuous-Time Unit-Specific Event-Based Formulation for Short-Term Scheduling of Multipurpose Batch Processes: Resource Constraints and Mixed Storage Policies. , 2004 .

[2]  Christodoulos A. Floudas,et al.  Continuous-time versus discrete-time approaches for scheduling of chemical processes: a review , 2004, Comput. Chem. Eng..

[3]  Christodoulos A. Floudas,et al.  Continuous-Time Optimization Approach for Medium-Range Production Scheduling of a Multiproduct Batch Plant , 2002 .

[4]  Christodoulos A. Floudas,et al.  Effective continuous-time formulation for short-term scheduling. 3. Multiple intermediate due dates , 1999 .

[5]  C. Floudas,et al.  A Novel Continuous-Time Modeling and Optimization Framework for Well Platform Planning Problems , 2003 .

[6]  Christodoulos A. Floudas,et al.  Mixed Integer Linear Programming in Process Scheduling: Modeling, Algorithms, and Applications , 2005, Ann. Oper. Res..

[7]  Ignacio E. Grossmann,et al.  New General Continuous-Time State−Task Network Formulation for Short-Term Scheduling of Multipurpose Batch Plants , 2003 .

[8]  Gintaras V. Reklaitis,et al.  Overview of Scheduling and Planning of Batch Process Operations , 1996 .

[9]  C. Floudas,et al.  Effective Continuous-Time Formulation for Short-Term Scheduling. 1. Multipurpose Batch Processes , 1998 .

[10]  Christodoulos A. Floudas,et al.  Design, synthesis and scheduling of multipurpose batch plants via an effective continuous-time formulation , 2001 .

[11]  Christodoulos A. Floudas,et al.  Effective Continuous-Time Formulation for Short-Term Scheduling. 2. Continuous and Semicontinuous Processes , 1998 .

[12]  Christodoulos A. Floudas,et al.  Scheduling of Tanker Lightering via a Novel Continuous-Time Optimization Framework , 2003 .