ABSTRACT The global use of fossil energy sources has led to the need to develop technologies capable of mitigating its consequences. One such option is anaerobic biodigestion, which is already scientifically well-established, although the use of its main products (biogas and biomethane) still requires further development before they can be employed in automotive vehicles, largely due to technical issues concerning their storage. The storage of methane using adsorption (Adsorbed Natural Gas - ANG) is a technology that requires less energy and moderate pressures and temperatures. However, the main storage techniques continue to be those that involve high pressures and/or cryogenic temperatures. The present work evaluates the performance of an unprecedented prototype developed by UFPR for the storage of methane by adsorption, employing commercial activated carbon. The factorial design (2²) indicated that the storage capacity of the system was 39.41 V /V using activated carbon, and the desorption process was effective at 60ºC. Thus, the use of adsorbents of low cost and easy access can provide very interesting results (>100 V / V), which contributes to make the technology viable.

RESUMO O armazenamento de metano na forma adsorvida em carvão ativado (ANG - Adsorbed Natural Gas) tem despertado interesse nos últimos anos por empregar baixas pressões quando comparado ao gás natural comprimido (CNG - Compressed Natural Gas) e temperatura ambiente, e ainda por configurar uma alternativa importante à utilização de biometano oriundo da purificação de biogás em sistemas estacionários e veiculares. O presente estudo objetivou uma avaliação do armazenamento de metano em carvão ativado sob diferentes condições de temperatura e vazão de carga em um sistema protótipo. Metano foi inserido no sistema protótipo preenchido com carvão ativado vegetal a pressão reduzida (10 bar) utilizando planejamento fatorial 2². Na dessorção do sistema foram levantadas cinéticas para identificar a melhor condição a ser adotada entre a condução dos ensaios de armazenamento para permitir o reuso do carvão ativado. O carvão ativado foi caracterizado com as técnicas de fisissorção de N2, para determinação das características texturais, picnometria de gás Hélio, para quantificação da densidade das partículas, e microscopia eletrônica de varredura para observação da estrutura morfológica. Nas condições adotadas no presente estudo, foi observado o aumento da capacidade de adsorção do carvão com a diminuição da temperatura e da vazão de metano no intervalo avaliado. Com o presente estudo foi possível aumentar a capacidade de armazenamento em aproximadamente 3 vezes (34,56 V V-1) quando comparado com o cilindro vazio (13,14 V V-1), comprovando a eficácia do adsorvente e do conjunto de variáveis adotado. Em adição, o estudo cinético de dessorção de metano resultou na adoção da temperatura de 60 ºC durante 30 min para total entrega do metano.

ABSTRACT Methane storage in adsorbed form in activated carbon (ANG - Adsorbed Natural Gas) has attracted attention in recent years by applying reduced pressures when compared to CNG (Compressed Natural Gas) technology and reduced temperatures, and also for representing an important alternative use of biomethane derived from biogas purification in vehicular and stationary systems. This study aimed an evaluation of methane storage in activated carbon under different conditions of temperature and flow rate of charge in a prototype system. Methane was inserted into the prototype system filled with activated vegetable carbon at reduced pressure (10 bar) using factorial design 2². In the desorption of the system, kinetics was raised to identify the best condition to be adopted between the conduction of the storage trials to allow activated carbon reuse. Activated carbon was characterized with N2 physisorption for the determination of textural characteristics, Helium gas pycnometry for quantification of particle density, and scanning electron microscopy for observation of the morphological structure. Under the conditions adopted in this study, an increase was observed in activated carbon adsorption capacity with decreasing temperature and flow rate during the evaluated range. With this study, it was possible to increase a cylinder storage capacity in approximately 3 times (34,56 V V-1) compared to the hollow cylinder (13,14 V V-1), proving the effectiveness of the adsorbent and the set of variables adopted. In addition, the kinetic study of methane desorption resulted in the adoption of 60 ºC for 30 min for the complete methane delivery.

Este estudo teve como objetivo realizar processo de co-digestão anaeróbia da vinhaça, oriunda dos processos de produção do etanol hidratado, e dos resíduos de suinocultura. Utilizaram-se biodigestores tubulares sob diferentes condições de temperatura e avaliaou-se a eficiência na remoção de sólidos, demanda química de oxigénio (DQO) e a produção de biogás. Para isso utilizaram-se dois reatores, sendo um deles controlado termicamente enquanto o outro permaneceu à temperatura ambiente. Determinaram-se três tempos de retenção hidráulica com 13 dias cada, realizando-se diariamente análises no efluente dos reatores. As eficiências de remoção de sólidos totais voláteis (STV) foram de 29,9% para o reator termicamente controlado contra 25,4% do reator a temperatura ambiente, para eficiência de remoção de DQO verificaram-se valores médios de 69,0% no Reator 1 e 68,4% no Reator 2. O controle da temperatura proporcionou produção acumulada de metano ao Reator 1330% superior ao reator mantido em condição ambiental.

The current research aimed to perform the process of anaerobic co-digestion of vinasse, originated from the production of hydrous ethanol, and from the residues of swine raising processes using tubular biodigesters under different temperature conditions, evaluating the removal efficiency of solids, COD removal and biogas production. For this, it was used two reactors, one of which was thermally controlled while the other remained at room temperature. Three hydraulic retention times were determined with 13 days each, performing daily analysis on the reactor effluent. The TVS removal efficiencies were 29.9% for the thermally controlled reactor and 25.4% for the room temperature reactor, for the COD removal efficiency, it was verified mean values of 69.0% in the Reactor 1 and 68.4% in the Reactor 2. The temperature control caused accumulated methane production to the Reactor 1,330% higher than the reactor kept in environmental conditions.