CORE DISCUSSION PAPER 2001/42 A DISCUSSION OF PRODUCTION PLANNING APPROACHES IN THE PROCESS INDUSTRY Y. CRAMA 1 , Y. POCHET 2 and Y. WERA 3 September 2001 Abstract In this paper, we discuss the literature on production planning ap- proaches in the process industry. Our contribution is to underline the differences, as well as the similarities, between issues and models arising in process environments and better known situations arising in discrete manufacturing, and to explain how these features affect the optimiza- tion models used in production planning. We present an overview of the distinctive features of process industries, as they relate to produc- tion planning issues. We discuss some of the difficulties encountered with the implementation of classical flow control techniques, like MRP or JIT, and we describe how various authors suggest to solve these difficulties. In particular we focus on the concept of “recipe”, which extends the classical Bill of Materials used in discrete manufacturing, and we describe how the specific features of recipes are taken into account by different production planning models. Finally,we give a survey of specific flow control models and algorithmic techniques that have been specifically developed for process industries. Keywords: Production flow control, process industry, blending models 1 Corresponding author. University of Li` ege, Boulevard du Rectorat 7 (B31), 4000 Li` ege, Belgium, y.crama@ulg.ac.be 2 Catholic University of Louvain, CORE and IAG, Voie du Roman Pays 34, 1348 Louvain-la-Neuve, Belgium, pochet@core.ucl.ac.be 3 University of Li` ege and Corman S.A., Route de la Gileppe 4, 4834 Go´ e, Belgium, yannic.wera@corman.be Yves Pochet and Yves Crama’s research was carried out with financial support of the project TMR-DONET ERB FMX-CT98-0202 of the European Community. Yves Crama acknowledges the partial financial support of ONR (grant N00014-92-J-1375) and research grants from the Natural Sciences and Engineering Research Council of Canada (NSERC). Yves Pochet’s research was carried within the framework of the Belgian Program on Interuniversity Poles of Attraction initiated by the Belgian State, Prime Minister’s Office, Science Policy Programming. The scientific responsability is assumed by the authors.