Modeling and energy integration of the ethanol production process from sugarcane biomass

Orientador: Silvia Azucena Nebra de PérezTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: A produção de etanol a partir da hidrolise enzimática do bagaço e eventualmente da palha se apresenta como uma alternativa de grande interesse, uma vez que permite ampliar significativamente a produção sem necessidade de aumentar a área plantada de cana. Não obstante, a introdução da hidrolise se apresenta como um verdadeiro desafio uma vez que o bagaço e o combustível do processo atual e ao mesmo tempo e matéria prima para o novo. Assim, o presente estudo tem como objetivo elaborar propostas de integração energética, e realizar avaliações do potencial de incremento da produção de etanol do processo integrado. Para este fim foi utilizado o simulador Aspen Plus® como ferramenta de analise e o método Pinch-Point para realizar a integração energética. Um estudo foi realizado com a finalidade de verificar se as propriedades das substancias envolvidas no processo são calculadas apropriadamente pelo simulador. O sistema de cogeração também foi modelado no simulador e depois inserido na modelagem do processo de produção. Em uma primeira analise foi modelado o processo de produção de etanol por hidrolise enzimática inserido no processo convencional considerando o arranjo (layout) usual das usinas sucroalcooleiras hoje. Os resultados desta analise foram modestos apresentando um incremento na produção de etanol de 9,7%, o que indicou que mudanças que visem a otimização do sistema em termos de uso de energia devem ser realizadas no processo tradicional. Em um segundo estudo foi avaliado o potencial de produção de etanol considerando a integração térmica das correntes do processo, utilizando o método Pinch-Point, e visando a minimização do consumo de utilidades quentes e frias. Este segundo estudo apresentou melhores resultados, atingindo um incremento na produção de etanol de 22,4% quando são consideradas membranas para a concentração do licor de glicose obtido no processo de hidroliseAbstract: Ethanol production process by enzymatic hydrolysis of sugarcane bagasse and eventually from sugarcane trash presents itself as an interesting alternative since to it allows a significant ethanol production increase without needing to increase the planted area. The introduction of the hydrolysis process is a true challenge, since bagasse is the fuel of the current process while it is raw material for the hydrolysis process. Thus, the aim of this study is to accomplish proposals for energy integration of processes and to assess the ethanol production potential from the hydrolysis process integrated to the conventional process. Simulator Aspen Plus was used as analysis tool and Pinch-Point method was applied in order to perform the thermal integration of the system. A study of properties was carried out to verify the simulator accuracy in property calculations. The cogeneration system was modeled in the simulator and after, it was inserted into the modeling of the ethanol production process. In a first analysis the enzymatic hydrolysis process inserted in the conventional process, considering the current configuration of sugarcane mills today, was modeled. The results of this preliminary study were modest obtaining an ethanol production increase of 9,7%, which indicates that changes in conventional production process should be done. These changes should improve and optimize the system in terms of energy use. In a second analysis the potential of ethanol production was evaluated, considering the heat integration of process streams using the Pinch Point method. This method aims to minimize the consumption of hot and cold utilities in the integrated system. This second analysis presented better results, obtaining an ethanol production increase of 22,4% when the concentration of glucose liquor is accomplished by a membrane systemDoutoradoTermica e FluidosDoutor em Engenharia Mecânic

Estimativa do potencial energético dos resíduos sólidos urbanos com uso da tecnologia de digestão anaeróbica em biodigestores

Este artigo tem por como objetivo estimar o potencial energético da fração orgânica dos resíduos sólidos urbanos dispostos no aterro sanitário de Caieiras com o uso da tecnologia de digestão anaeróbica em biodigestores. Para estimar o potencial energético foram usados dois modelos matemáticos que permitem estimar a produção de metano em função dos diversos fatores que interferem no processo (concentração de acetato e de micro-organismos, variação do pH, dentre outros). De acordo com os resultados obtidos seria possível uma potência elétrica mínima de 32,5 MW e uma potência máxima de 47,0 MW. Baseados nos resultados obtidos, conclui-se que a produção anual de eletricidade, obtidas a partir da combustão do biogás, produzido a partir do processo de digestão anaeróbia, representa cerca de 70% do consumo de energia elétrica (residencial, comercial, rural, industrial e iluminação pública) do município de Caieiras (no qual o aterro está localizado), no ano de 2016.This paper aims to estimate the energy potential of the organic fraction of municipal solid waste disposed at the Caieiras landfill with the use of anaerobic digestion technology in digesters. In order to estimate the energy potential, two mathematical models were used to estimate methane production as a function of the various factors that influence the process (acetate and microorganisms concentration, pH variation, among others). According to the results obtained would be possible a minimum electric power of 32.5 MW and a maximum power of 47.0 MW. Based on the results obtained, it is concluded that the annual production of electricity, obtained from the combustion of biogas, produced from the anaerobic digestion process, represents about 70% of the electric energy consumption (residential, commercial, rural, industrial And public lighting) of the municipality of Caieiras (in which the landfill is located), in the year 2016.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Evaluation of absorption refrigeration systems 'H IND. 2'O/LiBr and their possibility of introduction in the tertiary sector using natural gas

Orientador: Silvia Azucena Nebra de PerezDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecanicaResumo: Neste trabalho e feita uma revisão em relação à participação do gás natural na matriz energética mundial, brasileira e no Estado de São Paulo. Características do setor terciário, assim como da utilização do gás natural neste setor de consumo, são apresentadas também na primeira parte. Foi feita uma revisão das tecnologias de utilização de gás natural no setor terciário, assim como da tecnologia dos sistemas de refrigeração por absorção, das diferentes configurações do ciclo, e dos fluidos de trabalho utilizados neste tipo de sistema. Uma metodologia para o calculo da exergia da solução água brometo de lítio, comumente utilizada como fluido de trabalho em sistemas de refrigeração por absorção para condicionamento de ambientes, foi elaborada. Para a realização das analises exegética e exergoeconomica do sistema foi realizado o calculo da exergia total dos fluidos de trabalho considerando as parcelas de exergia química e física. A analise exegética compreendeu o calculo da irreversibilidade em cada componente do sistema assim como da total. Na ultima parte do trabalho foi realizada a analise termodinâmica, exegética e exergoeconomica do sistema de refrigeração por absorção de simples e duplo efeito H2O/LiBr, considerando como fontes de aquecimento um sistema de queima direta de gás natural e energia de rejeito de um sistema de cogeração. Os resultados são comparados e discutidosAbstract: A review about the participation of the natural gas in the energetic matrix was done in this work, considering the scope international, Brazilian and the Sao Paulo State. Characteristics of the tertiary sector and the natural gas utilization in this consumption sector are also presented. A review about the technologies of utilization of natural gas in the tertiary sector was also done. In the following part, the technology of absorption refrigeration systems, different configurations of the cycle and working fluids were reviewed. A methodology for the exergy calculation of the lithium bromide ¿ water solution was elaborated. The lithium bromide ¿ water solution is widely utilized as working fluid in absorption refrigeration system for air conditioning. The exergy calculation takes in account the chemical and physical parcel of the exergy, which is important to realize the exergetic and exergoeconomic analysis of the system. In the last part of the work it was done a thermodynamic, exergetic and exergoeconomic analysis of the absorption refrigeration system H2O/LiBr of single and double effect. The exergetic analysis included the irreversibility calculation in each component and the total irreversibility of the system. Two different energy sources were considered: direct heating through natural gas combustion and the utilization of rejected energy in a cogeneration system. The different results were compared.MestradoMestre em Planejamento de Sistemas Energético

New alternatives for the fermentation process in the ethanol production from sugarcane: Extractive and low temperature fermentation

Ethanol is produced in large scale from sugarcane in Brazil by fermentation of sugars and distillation. This is currently considered as an efficient biofuel technology, leading to significant reduction on greenhouse gases emissions. However, some improvements in the process can be introduced in order to improve the use of energy. In current distilleries, a significant fraction of the energy consumption occurs in the purification step distillation and dehydration since conventional fermentation systems employed in the industry require low substrate concentration, which must be distilled, consequently with high energy consumption. In this study, alternatives to the conventional fermentation processes are assessed, through computer simulation: low temperature fermentation and vacuum extractive fermentation. The aim of this study is to assess the incorporation of these alternative fermentation processes in ethanol production, energy consumption and electricity surplus produced in the cogeneration system. Several cases were evaluated. Thermal integration technique was applied. Results shown that the ethanol production increases between 3.3% and 4.8% and a reduction in steam consumption happens of up to 36%. About the electricity surplus, a value of 85 kWh/t of cane can be achieved when condensing extracting steam turbines are used. (C) 2014 Elsevier Ltd. All rights reserved

Double-effect distillation and thermal integration applied to the ethanol production process

A double-effect distillation system allows a significant reduction in energy consumption, since the condensers and reboilers of different columns can be integrated thermally. To achieve this goal, some columns operate under a vacuum, while others operate close to atmospheric pressure. These pressure levels bring about different temperature levels, allowing energy recovery. Thus, the aim of this study is to assess the incorporation of double-effect distillation in ethanol production, and its impact on energy consumption and electricity surplus production in the cogeneration system. Moreover, because double-effect distillation and thermal integration involve an increase in equipment costs, an economic assessment was done. Several cases were evaluated and a thermal integration technique was applied, in order to integrate the overall process. The thermal integration study showed that it is possible to integrate the juice concentration step (multiple effect evaporation system) in the overall process without additional thermal consumption, through the selection of a suitable set of pressures in the evaporation system. The results showed a reduction in steam consumption of between 17% and 54%, in comparison with the Base Case. Regarding the electricity surplus, this increased by up to 22% when extraction condensing steam turbines were adopted. (C) 2015 Elsevier Ltd. All rights reserved

Reduction of process steam demand and water-usage through heat integration in sugar and ethanol production from sugarcane - Evaluation of different plant configurations

The sugarcane industry represents one of the most important economic activities in Brazil producing sugar and ethanol for the internal and external markets. There are also plants dedicated only to ethanol production. The aim of this study is to accomplish a joint assessment to evaluate the reduction of process steam demand and water usage obtained through heat integration and an exergy analysis to quantify the reduction in irreversibility generation owing to heat integration procedure. Two configurations of plant were analysed Case I - all sugarcane juice is destined to produce ethanol without sugar production and Case II - distribution of 50%/50% of total recoverable sugars in sugar and ethanol production. Simulations in ASPEN PLUS (R) software were performed in order to evaluate the mass and energy balances and heat integration using the Pinch Method was applied in order to minimize the utilities consumption. The results showed that heat integration promoted a reduction in steam consumption of 35% approximately, while the reduction in water consumption (water collecting requirement) was 24 and 13% in comparison to the conventional cases without heat integration. (c) 2015 Elsevier Ltd. All rights reserved