Strategies for optimization of a Sugar House

GUILLERMO A. DURAND; DENNIS BONNÉ; STEPHEN BRIDGES; STEN BAY JØRGENSEN

Lyngby (Dinamarca)

Congreso; CAPEC Annual Meeting 2001; 2001

Computer Aided Process-Product Engineering Center - Technical University of Denmark

Background Batch processing is most important since half the chemical products are produced in batch processes. Batch processing consists of a sequence of processing steps, which also may take place between continuous processes in a production line. A special problem in bath processing is the possible variation in task performance. Time varying conditions can make the throughput vary widely. If the processing capabilities of upstream and downstream units do not match those of the batch stage(s) then accumulation problems may arise. The most common solution is to use more than one batch unit and schedule their operation to make the overall production of the batch process as similar as possible to that of the upstream and downstream continuous stages. The scheduling has also to be planned considering the optimization of the operation in order to reach the maximum utilization of the total process plant, constrained by the batch stage and intermediate storage sizes. The scheduling basically consists of a series of decisions of whether to start or not a specified batch unit at a determined moment. The discrete time control problem and the dynamic batch-to-batch behavior of the units make the dynamic programming approach a suitable methodology for optimizing scheduling. Objectives To develop a robust optimal operation procedure for a sugarhouse that is subject to disturbances. Objective function: Profit maximization subject to several constraints: -         Unit capacities (crystallizer, centrifuges and storage vessels) -         Limited utilities (steam and vacuum) -         Concentration profile(s) -         Limited operator capacity To develop a dynamic model of the sugarhouse for prediction of the robust optimal operation procedure performance. Project status A scheduling algorithm based on dynamic programming has been developed. A dynamic model of the sugarhouse suitable to be used in the scheduling algorithm is being developed.