Methodologie pour la reduction simultanee eau-energie dans les usines integrees de papier journal

The pulp and paper industry faces continuous challenges related to its considerable water and energy usage. Sudden increase in energy costs, mainly related to fluctuating prices of oil and natural gas, significantly affects mill profitability. In the context of the Kyoto protocol, industry must also reduce its greenhouse gases emissions. Furthermore, environmental requirements impose increasingly stringent restrictions on effluent discharge. Zero-effluent operation can be hence the ultimate solution in the long term to face this problem. In this regard, programs for water and energy reduction are needed to anticipate future constraints and guarantee a sustainable mill operation.; Simultaneous reduction of water and energy usage requires the application of a holistic and systematic approach. Given the interactive nature of water and energy networks in integrated paper mills, the system needs to be analyzed globally rather than on a project-by-project basis.; Such an approach has not been yet applied to pulp and paper processes, especially in retrofit design. Classical thermal pinch analysis is a widely applied method to study energy in pulp and paper mills. However, its application is not suitable for simultaneous water and energy reduction since mass and -energy interactions are not systematically taken into account. As to mass pinch analysis, its application to pulp and paper processes is far from being practical due to of the lack of a modeling framework capable of accurately representing the interaction between pulp components.; The main objective of this thesis aims at developing a systematic and practical methodology to generate water and energy reduction programs that take into consideration both the short and long term operation.; The methodology starts by defining the energy profile of the mill. Then a three-step analysis is applied: (1) Exploration of typical solutions implemented in pulp and paper processes through a process study; (2) Identification of direct heat exchange projects (i.e. stream mixing and recirculation projects) using a modified pinch analysis; (3) Identification of indirect heat exchanger projects using a classical pinch analysis.; The use of pinch techniques in the three-step analysis allows for a systematic identification of project opportunities which are then organized into programs that are consistent with both mill short-term and long-term mill objectives. (Abstract shortened by UMI.)...