Avaliação Técnico-Econômica de Plantas de Gaseificação do Lixo Urbano para Geração Distribuída de Eletricidade.

É crescente a demanda energética para sustentar o desenvolvimento do Brasil, que já é a 6ª potência econômica mundial de acordo com do FMI em 2012. As hidroelétricas são a principal fonte de energia do país, mas a crescente demanda induz a busca por fontes alternativas. Em 2010, a população Brasileira (> 190 milhões de habitantes) segundo IBGE despejou diretamente no solo, sem qualquer tratamento, cerca de 63 mil ton.RSU/dia. O RSU despejado deste modo causa danos ambientais por meio da produção de gases como CH₄ e CO₂, poluindo o ar, e por meio da infiltração do chorume, e contaminação por meio dos metais pesados, micro-organismos, poluindo a água subterrânea e superficial e o solo. Unindo a necessidade de gerar energia elétrica e de reduzir o impacto ambiental do gerenciamento do RSU, a gaseificação apresenta-se como uma possível solução. O objetivo deste trabalho foi analisar a viabilidade econômica da instalação de uma usina de gaseificação de RSU para geração de energia elétrica por município brasileiro. A tecnologia utilizada foi a gaseificação. Os municípios brasileiros foram classificados por faixas populacionais. Este parâmetro foi a base para o cálculo da geração de RSU e do projeto da usina com equipamentos disponíveis no mercado brasileiro. Foram avaliadas variáveis de custo (equipamentos e instalação, operação, manutenção e juros do financiamento dos equipamentos) e variáveis de rendimentos (energia elétrica, quantidade de materiais recicláveis, taxa de tratamento do lixo e créditos de carbono). Foi realizada uma análise para cada grupo populacional combinando 3 diferentes cenários econômicos com taxas anuais de juros de 10,58% para o cenário 1, 7,5% para o cenário 2 e de 15% para o cenário 3. A viabilidade econômica foi definida pelo cálculo da VPL (valor presente líquido) e da TIR (taxa interna de retorno). O VPL foi positivo para os municípios com mais de 60.714 habitantes para o cenário 1, 34.203 para o cenário e de 259.845 habitantes para o cenário 3. Uma usina de gaseificação com capacidade para 60.714 habitantes pode gerar 905 kW/ton. e reduzir a massa de 74 ton. de RSU/dia para o cenário 1, 794 kW/ton. e reduzir a massa de 54 ton. de RSU/dia para o cenário 2 e 1.065 kW/ton. e reduzir a massa de 317 ton. de RSU/dia no cenário 3. A viabilidade econômica aumenta com a instalação de usinas maiores, sendo que quanto maior a capacidade da usina instalada, menores os custos e maiores os lucros. Quanto mais populoso o município maior a viabilidade econômica da instalação de uma usina de gaseificação

anaerobic digestion of liquid fraction coffee grounds at laboratory scale evaluation of the biogas yield

Abstract Coffee is one of the most popular beverage in the world. The International Coffee Organization (ICO) in the last 4 years registered an average world consumption higher than 8x10 6 tons. Over 50% of this mass is discarded after use, becoming a significant waste source known as spent coffee grounds (SCG). SCG usage as a raw material for biogas production emerges with great potential. It is a biomass that does not need pre-treatment, rich in lipids and can be easily separated in bars and restaurants. Lipid concentrations in SCG can reach more than 25% of its dry weight and have a good biogas production behavior, producing over 1 liter of CH 4 /g-VS. In this paper, the analysis of biogas yield potential of SCG recovery is presented using a laboratory scale batch anaerobic reactor, fed with the liquid fraction obtained by spent coffee filtration. Airtight glass reactors have been realized to guarantee the anaerobic digestion conditions. The reactors, divided into two groups A and B, fed with SGC and cow manure respectively, have been monitored for 22 days at a temperature of 37 °C. The accumulated methane production for a total of 1444 ml of biogas for group A and 1047 ml of methane for Group B was observed. Group A had an output of 296 ml.CH 4 /g-VS and group B 312 ml.CH 4 /g-VS. Group A presented fractions of 53.7% of CH 4 and 37.80% of CO 2 . The B group showed 36.7% of CH 4 and 27.9% of CO 2 . In the Group A, the methane production from SGC, reached concentration higher than 50%. This result shows the SCG liquid fraction energy recovery potential using an anaerobic digestion process

pyrolysis in screw reactors a 1 d numerical tool

Abstract This paper is focused on the numerical analysis of a screw pyrolyzer with special attention on kinetics, heat and mass transfer phenomena by means of a computational 1D tool. A steady-state model has been developed to generate temperature profiles and conversion patterns over the reactor axis. Residence time distribution capabilities have been considered to take into account the axial dispersion. The framework, including heat transport processes, is based on a 4 parallel Distributed Activation Energy Model. Its structure includes the three major biomass pseudo-component occurring in the biomass thermal degradation. The results of a generic biomass are then analyzed in terms of products distribution and heat transfer characteristics

Review of biochar role as additive in anaerobic digestion processes

because of the urgent need to provide renewable energy sources and efficiently manage the continuously growing amount of organic waste. Biochar (BC) is an extremely versatile material, which could be produced by carbonization of organic materials, including biomass and wastes, consistently with Circular Economy principles, and “tailor-made” for specific applications. The potential BC role as additive in the control of the many wellknown critical issues of AD processes has been increasingly explored over the past few years. However, a clear and comprehensive understanding of the connections between BC and AD is still missing. This review paper analyses and discusses significant references (review articles, research papers and international databases and reports), mostly published in the last 10 years. This review is aimed at addressing three key issues related to the better understanding of the BC role in AD processes: 1. Investigation of the influence of BC properties on AD performances and of their ability to counteract its main challenges; 2. Assessment of the optimal BC production chain (i.e. feedstock-pyrolysis-activation) to achieve the desired features; 3. Evaluation of the economic and environmental advantages connected to BC use in AD processes, compared to conventional solutions applied to address AD challenges

Avaliação Técnico-Econômica de Plantas de Gaseificação do Lixo Urbano para Geração Distribuída de Eletricidade.

É crescente a demanda energética para sustentar o desenvolvimento do Brasil, que já é a 6ª potência econômica mundial de acordo com do FMI em 2012. As hidroelétricas são a principal fonte de energia do país, mas a crescente demanda induz a busca por fontes alternativas. Em 2010, a população Brasileira (> 190 milhões de habitantes) segundo IBGE despejou diretamente no solo, sem qualquer tratamento, cerca de 63 mil ton.RSU/dia. O RSU despejado deste modo causa danos ambientais por meio da produção de gases como CH₄ e CO₂, poluindo o ar, e por meio da infiltração do chorume, e contaminação por meio dos metais pesados, micro-organismos, poluindo a água subterrânea e superficial e o solo. Unindo a necessidade de gerar energia elétrica e de reduzir o impacto ambiental do gerenciamento do RSU, a gaseificação apresenta-se como uma possível solução. O objetivo deste trabalho foi analisar a viabilidade econômica da instalação de uma usina de gaseificação de RSU para geração de energia elétrica por município brasileiro. A tecnologia utilizada foi a gaseificação. Os municípios brasileiros foram classificados por faixas populacionais. Este parâmetro foi a base para o cálculo da geração de RSU e do projeto da usina com equipamentos disponíveis no mercado brasileiro. Foram avaliadas variáveis de custo (equipamentos e instalação, operação, manutenção e juros do financiamento dos equipamentos) e variáveis de rendimentos (energia elétrica, quantidade de materiais recicláveis, taxa de tratamento do lixo e créditos de carbono). Foi realizada uma análise para cada grupo populacional combinando 3 diferentes cenários econômicos com taxas anuais de juros de 10,58% para o cenário 1, 7,5% para o cenário 2 e de 15% para o cenário 3. A viabilidade econômica foi definida pelo cálculo da VPL (valor presente líquido) e da TIR (taxa interna de retorno). O VPL foi positivo para os municípios com mais de 60.714 habitantes para o cenário 1, 34.203 para o cenário e de 259.845 habitantes para o cenário 3. Uma usina de gaseificação com capacidade para 60.714 habitantes pode gerar 905 kW/ton. e reduzir a massa de 74 ton. de RSU/dia para o cenário 1, 794 kW/ton. e reduzir a massa de 54 ton. de RSU/dia para o cenário 2 e 1.065 kW/ton. e reduzir a massa de 317 ton. de RSU/dia no cenário 3. A viabilidade econômica aumenta com a instalação de usinas maiores, sendo que quanto maior a capacidade da usina instalada, menores os custos e maiores os lucros. Quanto mais populoso o município maior a viabilidade econômica da instalação de uma usina de gaseificação

analysis of residual biomass fast pyrolysis at laboratory scale experimental and numerical evaluation of spent coffee powders energy content

Abstract The thermochemical pyrolysis process is one of the key intermediate processes to flexibly produce electric/thermal power output. In this paper, experimental results of a small externally heated biomass screw reactor are presented. This paper aims at validating a 1D-DAEM model with experimental data collected by varying maximum temperature in fast pyrolysis conditions. The experimental system, here used for the spent coffee conversion, has been specifically designed for allothermic processes, allowing for controlling heating and mass flow rates. A comparison with pellet has been performed to refer the observed yields to literature available data. The implemented four parallel reaction framework coupled with a DAEM model, is able to give results in very good agreement with the bio-oil experimental data yields, showing in any case prediction errors lower than 4.5%. The maximum bio-oil production has been observed at 500°C, both for the pellet and the spent coffee with yields respectively of 66% and 56%

Biomass fast pyrolysis in a shaftless screw reactor: A 1-D numerical model

The thermochemical conversion of biomass can be effective for flexible and programmable production of electric and thermal power. Only a few models have been developed so far in the literature to describe the behavior of a screw reactor system designed for biomass fast pyrolysis. The temperature profile plays a crucial role in particular for fast pyrolysis purposes. Hence, a complete heat transfer model is required to that aim. This paper is focused on numerical modeling of a shaftless screw pyrolyzer with special focus on the kinetic framework, as well as the description of heat and mass transfer phenomena. A steady-state model with constant wall temperature has been developed to generate temperature profile and conversion patterns along the reactor. Residence time distribution input has been considered to take into account non-perfect mass conveying characteristics. The model, including all the different heat flux mechanisms such as conduction, convection and radiation, is based on a four parallel Distributed Activation Energy Model. The structure includes the three major biomass pseudo-component occurring in the biomass thermal degradation, and namely cellulose hemicellulose and lignin, along with the moisture evaporation process. Numerical results have been compared with experimental data of spruce wood pellet fast pyrolysis obtained in a lab-scale screw reactor. Numerical temperature profiles for both gas and solid phase, are in good agreement with experimental data. The results obtained allow for demonstrating that the selected framework gives realistic conversion rates for all the fast pyrolysis products namely bio-oil, char, and syngas. The maximum bio-oil production from ground spruce wood has been observed at 500 °C, with yield in the range of 64%. Moreover, the results show a strong dependence on wall temperature, gas-solid heating rate, and screw geometry

Biomass fast pyrolysis in screw reactors: Prediction of spent coffee grounds bio-oil production through a monodimensional model

In the context of renewable sources exploitation, the thermochemical conversion of biomass may give a significant contribution to the flexible and programmable production of electric and thermal power. From this perspective, the biomass fast pyrolysis conversion process is more than a promising technology but only few models have been developed so far to describe the behavior of a screw reactor system. This paper is thus focused on numerical modeling of a shaftless screw fast pyrolyzer with special attention on the residence time distribution and the definition of the kinetic framework, as well as the heat and mass transfer phenomena representation. A steady-state model with constant wall temperature has been developed to generate temperature profile and conversion patterns along the reactor. Residence Time Distribution evaluation has been developed as well to take into account non-ideal mass conveying characteristics of the proposed reactor design. The reaction framework, considering the conductive, convective and radiative heat transfer mechanisms, is based on a 4 parallel Distributed Activation Energy Model. The structure includes the three major biomass pseudo-component occurring in the biomass thermal degradation, namely cellulose hemicellulose and lignin, together with the moisture evaporation process. The numerical results are compared with results collected experimentally from the fast pyrolysis of spent coffee grounds in a lab-scale screw reactor. Numerical temperature profiles for both the gas and solid phase are in good agreement with the experimental ones. The peak bio-oil production has been observed in the range of 500 °C. The results also show a strong dependence of results on wall temperature and gas-solid heating rate

Biochar characteristics and early applications in anaerobic digestion-a review

In the recent years, special focus has been given to the issues related to the management of biomass conversion systems by-products. In the view of transforming those products, mostly treated today as wastes, in valuable products, different valorization pathways can be considered. As an example, considerable attention has been devoted to the potential use of carbon-rich materials such as soil amendments and for long term carbon storage. These materials, produced by biomass thermochemical conversion are known as biochars. Several processes, from pyrolysis to gasification and hydrothermal carbonization, are today available for biochar production although characterized by relatively high costs. To overcome this restraint, an option is represented by the achievement of further economic benefits by extending its value chain. Coupling thermochemical processes to Anaerobic Digestion is thus an emerging field of research aimed at expanding usable feedstock with biologically recalcitrant substrates, such as paper, woody materials etc. Biochar in fact may promote the biomethane production, by acting both as support for bacteria colonies, conductor for electron transfer among species, sorbent for indirect inhibitors, and reactant in biochars labile carbon methanization. Thus, system integration of biogas and biochar is promising taking advantage of several profitable synergies. The aim of the paper is to review biochar characteristics and study early applications so far demonstrated and carried out, for the use of biochar in the anaerobic digestion processes

Spent coffee enhanced biomethane potential via an integrated hydrothermal carbonization-anaerobic digestion process

This study reports the implications of using spent coffee hydrochar as substrate for anaerobic digestion (AD) processes. Three different spent coffee hydrochars produced at 180, 220 and 250 °C, 1 h residence time, were investigated for their biomethane potential in AD process inoculated with cow manure. Spent coffee hydrochars were characterized in terms of ultimate, proximate and higher heating value (HHV), and their theoretical bio-methane yield evaluated using Boyle-Buswell equation and compared to the experimental values. The results were then analyzed using the modified Gompertz equation to determine the main AD evolution parameters. Different hydrochar properties were related to AD process performances. AD of spent coffee hydrochars produced at 180 °C showed the highest biomethane production rate (46 mL CH4/gVS.d), a biomethane potential of 491 mL/gVS (AD lasting 25 days), and a biomethane gas daily composition of about 70%