COORDINATION OF PROCESS INTEGRATION AND EXERGOECONOMIC METHODOLOGY FOR ANALYSIS AND OPTIMIZATION OF A PULP AND PAPER MILL

Abstract. By simultaneously applying pinch technology and the exergoeconomic method to a complex process system, bene cial and energy-ecient measures are identi ed. The three-link-model" exergoeconomic methodology optimizes the design and operability of a system. In this work, contrary to traditional exergoeconomic methods, a reversed method is used. The approach proposed for the optimization of such a complex system is to iteratively optimize subsystems. Since the reversed exergoeconomic method is used, assumptions considered by Tsatsaronis (based on four assumptions for calculating the costoptimal exergetic eciency and relative cost dierence) are not applicable and new assumptions are to be considered. Unlike traditional exergoeconomic methods, the product exergetic speci c cost is considered to be known and the objective will be to maximize the exergetic cost of the fuel. Heat ows costs are calculated with the assistance of a Pinch analysis. The strength of the combination of a Pinch analysis and the exergoeconomic method is elucidated in a case study applied to the Mazandaran wood and paper industry. Replacement of the pressure valve and Direct Cyclone Contact Evaporation (DCCE) is proposed, while by selection of the optimum decision variable and applying Pinch technology simultaneously, the recoverable black liquor could be increased by 7% and energy consumption decreased by 12%.