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Abstract: The aim of this study was to estimate the increase in industrial water consumption and withdrawal in a conventional sugarcane ethanol mill due to the introduction of second-generation ethanol production by a bagasse hydrolysis process, and to identify opportunities of water reuse, in order to minimize water withdrawal. Simulations in ASPEN PLUS® software were performed for mass and energy balances. Three cases were evaluated: a conventional ethanol production plant (Case I), and two second-generation plants incorporating bagasse hydrolysis differing only in their glucose concentration processes, namely by evaporation (Case II), and by membrane separation (Case III). Results show that external withdrawals of 738L/t of cane for Case I, 955L/t of cane for Case II and 853L/t of cane for Case III are required to cover the water deficit of the plant. These values are lower than the mandated limit of 1000L/t of cane for the sugar cane industry in the State of São Paulo. Moreover, for Cases II and III, which need large additional amounts of water for the hydrolysis stage, water usages of 10.77 and 9.38L of water per litre of ethanol produced were achieved, approaching the figure of 9.34L water per litre of ethanol produced by the conventional plants (Case I). This highlights the high potential for reduction practices based on the concept of energy and water integration. [Copyright &y& Elsevier]

Sugarcane is one of the most important industries of the Brazilian economy, and its main products are sugar and ethanol. Most of the industrial plants produce both products in an integrated process, in which the sugarcane bagasse is a by-product that can be used as a fuel in the cogeneration system. The bagasse is used as the only fuel of the plant, supplying all energy required for the process, and also producing electricity surplus that may be sold to the grid. In this paper, exergy analysis is used to assess an integrated sugar and ethanol plant with its cogeneration system. The plant was divided into eight sub-systems to evaluate the irreversibility generation in each separately. Data from typical sugarcane factories in Brazil, which produce sugar and ethanol, were used in the process simulation. The analysis has shown that the sub-systems with the highest contribution for the total irreversibility generation of the plant were co-generation, juice extraction and fermentation. Some improvements are proposed, including process thermal integration and the introduction of more efficient equipments for prime mover and steam and electricity generation. The analysis indicated that the total irreversibility could be reduced by 10% should those changes be implemented. [Copyright &y& Elsevier]

The Brazilian Energy Matrix is characterised by the presence of Renewables, whose participation reached 46.1% in 2019, equivalent to 133.8 Mtoe, of which 18.0% represented the sugarcane biomass share, 12.4% the hydraulic, 8.7% the wood and charcoal, and 7.0% corresponded to other renewables. The sugarcane industry produces sugar, ethanol, and electricity as main products and, considering the total primary energy produced, 52.861 Mtoe comes from sugarcane products (BEN, 2020). Another aspect of this industry is that it is energy self-sufficient, that being so, the energy used in the production process is also produced (from bagasse) in the same process. The aforementioned data show the significance of the sugarcane industry for the country and being this an energy industry, there is no doubt that the energy management holds importance to its industrial process. The present work will address different alternatives to improve the industrial process of sugarcane, aiming at optimising the energy management. Among the proposals to be presented, the following can be mentioned: increasing of electric energy in cogeneration, thermal integration of process streams using the Pinch Point method, second-generation ethanol production, water use in the process, integration with biodiesel production, vinasse disposition aiming at increasing energy production and reducing pollution. The main objective is to identify each proposal's influence on and contribution to the improvement of the performance and efficiency in the production process from sugarcane. • Renewables participates with 46,1 %, in the Brazilian Energy Matrix. • 18% is the sugarcane biomass share in the renewables in the Brazilian Energy Matrix. • The sugar cane industry produces simultaneously sugar, ethanol, and electricity. • The fuel used in the production process is also produced in it. • Different alternatives to improve the process of sugarcane industry were analysed. [ABSTRACT FROM AUTHOR]