Planning and scheduling models for refinery operations

The main objective of this work is to discuss planning and scheduling appli cations for refinery operations. Firstly, the development of a nonlinear pl anning model for refinery production is presented. The model is able to rep resent a general refinery topology and allows the implementation of nonline ar process models as well as blending relations. Considering the market lim itations for each oil derivative usually supplied by the refinery, the opti mization model is able to define new operating points, thus increasing the production of more valuable products, while satisfying all specification co nstraints. Real-world applications are developed for the planning of diesel production in the RPBC refinery in Cubatao (SP, Brazil) among others. The optimization results were compared to the current situation, where no compu ter algorithm is used and the stream allocation is made based on experience , with the aid of manual calculations. The new operating point represents a n increase of several million dollars in annual profitability. The second p art of the work addresses scheduling problems in oil refineries that are fo rmulated as mixed integer optimization models and rely on both continuous a nd discrete time representations. The problem of crude oil inventory manage ment that involves the optimal operation of crude oil unloading from pipeli nes, transfer to storage tanks and the charging schedule for each crude oil distillation unit will be discussed. Furthermore, the paper will consider the;development and solution of optimization models for short-term scheduli ng of a set of operations that includes: product receiving from processing units, storage and inventory management in intermediate tanks, blending in order to attend oil specifications and demands, and transport sequencing in oil pipelines. Important rear-world examples on refinery production and di stribution are reported: the diesel distribution problem at RPBC refinery a nd the production problems related to the fuel oil/asphalt and LPG areas of the REVAP refinery in Sao Jose dos Campos (SP, Brazil), which produces app roximately 80% of the national consumption. (C) 2000 Elsevier Science Ltd. All rights reserved.