Thermal Integration

The aim of this study is to make an evaluation of the possibilities of ethanol production increase through the introduction of bagasse hydrolysis process in conventional distilleries, considering the limiting situation of bagasse use: it is the major by-product in sugar and ethanol production and is burnt in boilers to satisfy the steam and power requirements of the process. Simulations in ASPEN PLUS® software were performed, in order to evaluate the mass and energy balances, for the integrated process, considering the pre-treatment of sugarcane bagasse by steam explosion. The cogeneration system was also modelled and integrated with the ethanol production process. It consists of a steam cycle with backpressure steam turbines and
parameters of live steam of 67 bar and 480°C. In all the cases studied it was considered that the steam flow used in the system was just that necessary to fulfil the process thermal needs, so, it was assumed that the surplus of bagasse was used to produce ethanol. The use of sugarcane trash was considered in order to accomplish the energetic needs of the overall process as well as lignin cake, which is a hydrolysis process residue. Several cases were evaluated, which include: the conventional ethanol production plant without hydrolysis (Case I), the conventional plant joint with hydrolysis process without thermal integration considering different solid contents in the hydrolysis reactor (Cases II, III and IV), and the conventional plant joint with the hydrolysis process considering thermal integration through Pinch method (Case V). The results shown a modest ethanol production increase of 9.7% for the situation without thermal integration and low solid content in the hydrolysis reactor, on the other hand, the case where thermal integration was applied presented an ethanol production increase of 17.4%.

Keywords:
Ethanol, sugarcane, enzymatic hydrolysis, thermal integration.

The aim of this paper is to discuss the major technological changes related to the implementation of large-scale cogeneration and biofuel production in the sugar and alcohol industry. The reduction of the process steam consumption, implementation of new alternatives in driving mills, the widespread practice of high steam parameters use in cogeneration facilities, the insertion of new technologies for biofuels production (hydrolysis and gasification), the energy conversion of sugarcane trash and vinasse, animal feed production, process integration and implementation of the biorefinery concept are considered. Another new paradigm consists in the wide spreading of sustainability studies of products and processes using the Life Cycle Assessment (LCA) and the implementation of sustainability indexes. Every approach to this issue has as an objective to increase the economic efficiency and the possibilities of the sugarcane as a main source of two basic raw materials: fibres and sugar. The paper briefly presents the concepts, indicators, state-of-the-art and perspectives of each of the referred issues.

The aim of this study is to make an evaluation of the possibilities of ethanol production increase through the introduction of bagasse hydrolysis process in conventional distilleries, considering the limiting situation of bagasse use: it is the major by-product in sugar and ethanol production and is burnt in boilers to satisfy the steam and power requirements of the process. Simulations in ASPEN PLUS® software were performed, in order to evaluate the mass and energy balances, for the integrated process, considering the pre-treatment of sugarcane bagasse by steam explosion. The cogeneration system was also modelled and integrated with the ethanol production process. It consists of a steam cycle with backpressure steam turbines and parameters of live steam of 67 bar and 480°C. In all the cases studied it was considered that the steam flow used in the system was just that necessary to fulfil the process thermal needs, so, it was assumed that the surplus of bagasse was used to produce ethanol. The use of sugarcane trash was considered in order to accomplish the energetic needs of the overall process as well as lignin cake, which is a hydrolysis process residue. Several cases were evaluated, which include: the conventional ethanol production plant without hydrolysis (Case I), the conventional plant joint with hydrolysis process without thermal integration considering different solid contents in the hydrolysis reactor (Cases II, III and IV), and the conventional plant joint with the hydrolysis process considering thermal integration through Pinch method (Case V). The results shown a modest ethanol production increase of 9.7% for the situation without thermal integration and low solid content in the hydrolysis reactor, on the other hand, the case where thermal integration was applied presented an ethanol production increase of 17.4%.

The aim of this paper is to discuss the major technological changes related to the implementation of large-scale cogeneration and biofuel production in the sugar and alcohol industry. The reduction of the process steam consumption, implementation of new alternatives in driving mills, the widespread practice of high steam parameters use in cogeneration facilities, the insertion of new technologies for biofuels production (hydrolysis and gasification), the energy conversion of sugarcane trash and vinasse, animal feed production, process integration and implementation of the biorefinery concept are considered. Another new paradigm consists in the wide spreading of sustainability studies of products and processes using the Life Cycle Assessment (LCA) and the implementation of sustainability indexes. Every approach to this issue has as an objective to increase the economic efficiency and the possibilities of the sugarcane as a main source of two basic raw materials: fibres and sugar. The paper briefly presents the concepts, indicators, state-of-the-art and perspectives of each of the referred issues.

The aim of this study is to make an evaluation of the possibilities of ethanol production increase through the introduction of bagasse hydrolysis process in conventional distilleries, considering the limiting situation of bagasse use: it is the major by-product in sugar and ethanol production and is burnt in boilers to satisfy the steam and power requirements of the process. Simulations in ASPEN PLUS® software were performed, in order to evaluate the mass and energy balances, for the integrated process, considering the pre-treatment of sugarcane bagasse by steam explosion. The cogeneration system was also modelled and integrated with the ethanol production process. It consists of a steam cycle with backpressure steam turbines and parameters of live steam of 67 bar and 480°C. In all the cases studied it was considered that the steam flow used in the system was just that necessary to fulfil the process thermal needs, so, it was assumed that the surplus of bagasse was used to produce ethanol. The use of sugarcane trash was considered in order to accomplish the energetic needs of the overall process as well as lignin cake, which is a hydrolysis process residue. Several cases were evaluated, which include: the conventional ethanol production plant without hydrolysis (Case I), the conventional plant joint with hydrolysis process without thermal integration considering different solid contents in the hydrolysis reactor (Cases II, III and IV), and the conventional plant joint with the hydrolysis process considering thermal integration through Pinch method (Case V). The results shown a modest ethanol production increase of 9.7% for the situation without thermal integration and low solid content in the hydrolysis reactor, on the other hand, the case where thermal integration was applied presented an ethanol production increase of 17.4%.

Abstract: The aim of this study is to make an evaluation of the possibilities of ethanol production increase through the introduction of bagasse hydrolysis process in conventional distilleries, considering the limiting situation of bagasse use: it is the major by-product in sugar and ethanol production and is burnt in boilers to satisfy the steam and power requirements of the process. Simulations in ASPEN PLUS® software were performed, in order to evaluate the mass and energy balances, for the integrated process, considering ...

The aim of this paper is to discuss the major technological changes related to the implementation of large-scale cogeneration and biofuel production in the sugar and alcohol industry. The reduction of the process steam consumption, implementation of new alternatives in driving mills, the widespread practice of high steam parameters use in cogeneration facilities, the insertion of new technologies for biofuels production (hydrolysis and gasification), the energy conversion of sugarcane trash and vinasse, animal feed production, process integration and implementation of the biorefinery concept are considered. Another new paradigm consists in the wide spreading of sustainability studies of products and processes using the Life Cycle Assessment (LCA) and the implementation of sustainability indexes. Every approach to this issue has as an objective to increase the economic efficiency and the possibilities of the sugarcane as a main source of two basic raw materials: fibres and sugar. The...

The aim of this paper is to discuss the major technological changes related to the implementation of large-scale cogeneration and biofuel production in the sugar and alcohol industry. The reduction of the process steam consumption, implementation of new alternatives in driving mills, the widespread practice of high steam parameters use in cogeneration facilities, the insertion of new technologies for biofuels production (hydrolysis and gasification), the energy conversion of sugarcane trash and vinasse, animal feed production, process integration and implementation of the biorefinery concept are considered. Another new paradigm consists in the wide spreading of sustainability studies of products and processes using the Life Cycle Assessment (LCA) and the implementation of sustainability indexes. Every approach to this issue has as an objective to increase the economic efficiency and the possibilities of the sugarcane as a main source of two basic raw materials: fibres and sugar. The...

The aim of this study is to make an evaluation of the possibilities of ethanol production increase through the introduction of bagasse hydrolysis process in conventional distilleries, considering the limiting situation of bagasse use: it is the major by-product in sugar and ethanol production and is burnt in boilers to satisfy the steam and power requirements of the process. Simulations in ASPEN PLUS® software were performed, in order to evaluate the mass and energy balances, for the integrated process, considering the pre-treatment of sugarcane bagasse by steam explosion. The cogeneration system was also modelled and integrated with the ethanol production process. It consists of a steam cycle with backpressure steam turbines and parameters of live steam of 67 bar and 480°C. In all the cases studied it was considered that the steam flow used in the system was just that necessary to fulfil the process thermal needs, so, it was assumed that the surplus of bagasse was used to produce ethanol. The use of sugarcane trash was considered in order to accomplish the energetic needs of the overall process as well as lignin cake, which is a hydrolysis process residue. Several cases were evaluated, which include: the conventional ethanol production plant without hydrolysis (Case I), the conventional plant joint with hydrolysis process without thermal integration considering different solid contents in the hydrolysis reactor (Cases II, III and IV), and the conventional plant joint with the hydrolysis process considering thermal integration through Pinch method (Case V). The results shown a modest ethanol production increase of 9.7% for the situation without thermal integration and low solid content in the hydrolysis reactor, on the other hand, the case where thermal integration was applied presented an ethanol production increase of 17.4%.

Oxygen–steam biomass gasification produces a high quality syngas with a high H 2 /CO ratio that is suitable for upgrading to liquid fuels. Such a gas is also well suited for use in conjunction with solid oxide fuel cells giving rise to a system yielding high electrical efficiency based on biomass. However, high costs for both oxygen supply equipment and operation are significant challenges for the commercial implementation of this technology. Mixed ionic and electronic conducting (MIEC) membranes can be used for oxygen separation from air at a lower energy consumption compared to cryogenic distillation, especially for small to medium scale plants. This paper examines different configurations for oxygen production using MIEC membranes where the oxygen partial pressure difference is achieved by creating a vacuum on the permeate side, compressing the air on the feed side or a combination of the two. The two configurations demonstrating the highest efficiency are then thermally integrated into an oxygen– steam biomass gasification plant. The energy demand for oxygen production and the membrane area required for a 6 MW th biomass plant are calculated for different operating conditions. Increasing the air feed pressure increases the energy consumption but decreases the membrane area. As an example, for the highest efficiency configuration working at a membrane temperature of 850 C, 6 bar of air feed pressure and 0.3 bar of permeate side pressure, 150 m 2 are needed to generate the oxygen for the 6 MW th plant at an energy consumption of 100 kW h per t O 2 .