17
th
European Symposium on Computer Aided Process Engineering – ESCAPE17
V. Plesu and P.S. Agachi (Editors)
© 2007 Elsevier B.V. All rights reserved. 1
An Automated Algorithm for Throughput
Maximization Under Fixed Time Horizon in
Multipurpose Batch Plants: S-Graph Approach
Tibor Holczinger,
a
Thokozani Majozi,
a,b
Mate Hegyhati
a
and Ferenc Friedler
a
a
Department of Computer Science, University of Pannonia, Egyetem u. 10, Veszprém,
H-8200, Hungary, Friedler@dcs.vein.hu
b
Department of Chemical Engineering, University of Pretoria, Lynnwood Road,
Pretoria, 0002, South Africa
Abstract
This paper presents a graph-theoretic technique for scheduling of multipurpose
batch processes with the objective of maximizing throughput over a fixed time
horizon. The presented technique is based on the S-graph framework which
embeds the necessary scheduling information pertaining to recipes of different
batches and possible resource allocation. The distinct feature of this
contribution is the irrelevance of time horizon discretization which has become
traditional in most mathematical programming techniques. Consequently, no
presupposition of time points is required, thereby rendering the technique truly
continuous in time. A comparison with time point based techniques is
conducted to demonstrate the performance.
Keywords: S-graph, batch plants, continuous-time, scheduling
1. Introduction
In its basic form, the problem of scheduling involves the optimal allocation of
tasks to limited resources. In a situation where the number of batches to be
produced for each product is known a priori, the objective is usually to
minimize makespan. On the other hand, it is also common in practice to have a