2 nd Mercosur Congress on Chemical Engineering 4 th Mercosur Congress on Process Systems Engineering 1 A MODEL FOR OPTIMAL OPERATION IN A SOY OIL AND FLOUR PLANT S. A. Faner, G. A. Durand, G. H. Crapiste and J. A. Bandoni 1 Planta Piloto de Ingeniería Química, PLAPIQUI (UNS–CONICET) Abstract. Argentina is the third larger worldwide exporter of soybean. In the year 2003 the country was also the leader in the oil and flour production. The soy industry in Argentina has been systematically growing in the last few years. Despite the size and added value of this industry, soybeans processing plants are mostly operated based of experience and heuristics, without taking advantage of systematic tools for the decision making process in the plants operation. This paper presents the development of a preliminary mathematical model for optimal operation of a soybean processing plant. The plant products are soy oil and high protein soy flour apt for human consumption. The model was developed based on unit’s input-output relationships and efficiencies, specific resource consumptions, etc. It consists in the maximization of the plant annual profit, constrained by the plant mass and energy balances and resource capacities. The model was implemented in the GAMS (Generic Algebraic Modeling System) environment. Results are presented for a typical operation scenario, characterized by raw material and energy costs, product prices, etc. Plant model parameters are also studied to determine their influence on optimal plant operation. Keywords: Optimization, Soybean process. 1. Introduction Argentina produces 18.1% of the total soy harvested in the world and is the third larger worldwide exporter of soybean, sharing 16% of the market. In the year 2003 the country was also leader in the production of oil and flour capturing 49% and 42% respectively of the world market (Cuniberti et al, 2004). The soy industry in Argentina has been systematically growing in the last few years, with the expectation of consolidation as the first world producer of oil and flour by the year 2006 (SAGPyA, 2004). Despite the size and added value of this industry, soybeans processing plants are mostly operated based of experience and heuristics, without taking advantage of systematic tools for the decision making process in the operation of the plants. There are some previous results in the literature concerning with the improvements of the operation of single units (Karnofsky, 1986), but to the authors knowledge, there has not been published yet a mathematical simulation and optimization model for a complete plant. In this paper we present the development of a preliminary mathematical model for optimal operation of a soybean processing plant. The plant under study produces two products: soy oil and high protein soy flour apt for human consumption (white flakes). The model was developed for a typical flowsheet of a soy processing plant, with mathematical equations based on mass and energy balances, units’s input-output relationships and efficiencies, power and steam consumptions, etc.. Most data to develop the model were obtained from literature and equipment vendors. The problem was posed as an optimization model consisting in the maximization of the plant annual benefit, constrained with model equations and resource constraints. The model was implemented in the GAMS (Generic Algebraic Modeling System) (Brooke et al., 1996) package. 1 Camino La Carrindanga Km. 7, (8000) Bahía Blanca, Argentina. Fax: +54 291 486 1600; E-mails: sfaner/gdurand/gcrapiste/abandoni@plapiqui.edu.ar