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Abstract Chemical quantitative characterization of biomass is relevant for waste to energy recovery technologies. In the present work, selected agroindustry solid residues from coffee crops – parchment and coffee shrub, i.e., stem, branches and leaves – were characterized. Properties such proximate, ultimate and biochemical composition, energy content, and thermogravimetric analysis, were evaluated. Results showed high values of higher heating value and volatile matter content. The silica contents are small for all samples. Additionally, the high content of extractives and lignin, reveal that these residual biomasses are more suitable for charcoal than cellulose pulp production. The extensive residue characterization provided valuable data that helped in outcome of the evaluation of different conversion technologies as being an environmentally friendly alternative, contributing to sustainable, reliable, carbon-neutral form of modern energy and upgrade the large quantity of waste generated by the coffee industry into energetically valued residues, by improving their management.

Industrial energy efficiency has received increasing attention in many countries because of its importance in the pursuit of energy supply security, increased economic competitiveness and in the mitigation of greenhouse gases emissions. This paper aimed to evaluate the energy consumption development of the Brazilian pulp and paper industry through an energy decomposition analysis and an energy efficiency index approach over a 30 years period. An international comparison with other important paper-producing countries (i.e., Canada, United States of America, Finland and Sweden) was carried out. It was concluded that despite a significant increase in the energy efficiency levels, responsible for 5.6 PJ savings in electricity consumption and for 38.6 PJ savings in fuels consumption between 1979 and 2009, a saving potential of 7.8 PJ and 146.2 PJ related to the annual consumption of electricity and fuels, respectively, could be identified in the Brazilian pulp and paper industry. Among the countries evolved in the international comparison, both the Swedish and Finnish industries were the most efficient, followed by the Brazilian, American and Canadian, the latter being the only one where there was a reduction in the energy efficiency levels from 1979 to 2009.

Cette étude évalue le potentiel de la pyrolyse rapide oxydative (OFP) des résidus de bois d'eucalyptus (EWR) pour produire de la bio-huile pour remplacer les combustibles fossiles dans les fours à chaux de l'industrie de la pâte. OFP est une alternative à la pyrolyse rapide en atmosphère inerte où une étape d'addition de chaleur séparée n'est pas nécessaire. L'OFP a été étudié en caractérisant le combustible à l'aide d'analyses chimiques proximales et élémentaires, d'analyses thermogravimétriques et de pouvoir calorifique. Ensuite, des expériences OFP dans un réacteur fluidisé autothermique à l'échelle pilote ont été réalisées avec EWR. Les produits de pyrolyse étaient des gaz, du bio-charbon et de la bio-huile (lourde et légère). Les gaz ont été brûlés et l'énergie utilisée pour chauffer l'air de fluidisation. Le rendement énergétique de la bio-huile lourde de 30% et le pouvoir calorifique inférieur de 21,4 MJ kg−1 indiquent un bon potentiel pour les applications de combustibles. Les résultats ont été utilisés pour modéliser et évaluer des cas à l'échelle industrielle. L'intégration avec la chaudière de récupération de l'usine de pâte et le cycle de vapeur permet de récupérer facilement la chaleur résiduelle considérable du processus lui-même, ainsi que la combustion des résidus solides et gazeux. L'analyse économique indique la rentabilité pour l'OFP des EWR fins de l'usine. Une valeur actualisée nette plus élevée, mais une période de récupération plus longue, a été obtenue pour une plus grande usine OFP utilisant des matières premières achetées. La production autonome a été jugée non rentable. Este estudio evalúa el potencial de la pirólisis oxidativa rápida (OFP) de los residuos de madera de eucalipto (EWR) para producir bioaceite para reemplazar los combustibles fósiles en los hornos de cal de la industria de la pulpa. OFP es una alternativa a la pirólisis rápida en atmósfera inerte donde no se requiere una etapa de adición de calor por separado. La OFP se estudió caracterizando el combustible mediante análisis químicos proximales y elementales, análisis termogravimétrico y valor calorífico. Luego, se realizaron experimentos de OFP en un reactor fluidizado autotérmico a escala piloto con EWR. Los productos de la pirólisis fueron gases, biocarbón y bioaceite (pesado y ligero). Los gases se quemaron y la energía se utilizó para calentar el aire de fluidización. Un rendimiento energético de bioaceite pesado del 30% y un valor calorífico inferior de 21,4 MJ kg-1 indican un buen potencial para aplicaciones de combustible. Los resultados se utilizaron para modelar y evaluar casos a escala industrial. La integración con la caldera de recuperación de la fábrica de pulpa y el ciclo de vapor permite una fácil recuperación del considerable calor residual del propio proceso, así como la combustión de residuos sólidos y gaseosos. El análisis económico indica la rentabilidad para OFP de los EWR finos de la fábrica. Se obtuvo un valor actual neto más alto, pero un período de recuperación más largo, para una planta de OFP más grande que utiliza materia prima comprada. La producción independiente se consideró no rentable. This study evaluates the potential of the oxidative fast pyrolysis (OFP) of eucalyptus wood residues (EWR) for producing bio-oil to replace fossil fuels in the lime kilns of the pulp industry. OFP is an alternative to inert-atmosphere fast pyrolysis where separate heat addition stage is not required. OFP was studied by characterizing the fuel using proximate and elemental chemical analyses, thermogravimetric analysis and heating value. Then, OFP experiments in a pilot-scale autothermal fluidized reactor were done with EWR. Pyrolysis products were gases, bio-char and bio-oil (heavy and light). The gases were burnt, and the energy used for heating the fluidization air. Heavy bio-oil energy yield of 30% and 21.4 MJ kg−1 lower heating value indicate good potential for fuel applications. The results were used to model and evaluate industrial-scale cases. Integration with the pulp mill recovery boiler and steam cycle allows easy recovery of the considerable waste heat from the process itself, as well as the combustion of solid and gaseous residues. Economic analysis indicates profitability for OFP of fine EWRs from the mill. A higher net present value, but longer payback period, was obtained for a larger OFP plant using purchased feedstock. Stand-alone production was found unprofitable. تقيّم هذه الدراسة إمكانات التحلل الحراري السريع المؤكسد لبقايا خشب الأوكالبتوس لإنتاج النفط الحيوي ليحل محل الوقود الأحفوري في أفران الجير في صناعة اللب. يعد OFP بديلاً للانحلال الحراري السريع في الغلاف الجوي الخامل حيث لا تكون مرحلة إضافة الحرارة المنفصلة مطلوبة. تمت دراسة OFP من خلال توصيف الوقود باستخدام التحليلات الكيميائية القريبة والعنصرية والتحليل الحراري وقيمة التسخين. بعد ذلك، تم إجراء تجارب OFP في مفاعل مميّع ذاتي الحرارة على نطاق تجريبي باستخدام EWR. كانت منتجات الانحلال الحراري عبارة عن غازات وفحم حيوي وزيت حيوي (ثقيل وخفيف). احترقت الغازات، واستخدمت الطاقة لتسخين هواء التميع. تشير طاقة الزيت الحيوي الثقيلة التي تبلغ 30 ٪ و 21.4 ميجا جول كغ-1 قيمة تسخين أقل إلى إمكانات جيدة لتطبيقات الوقود. تم استخدام النتائج لنمذجة وتقييم حالات النطاق الصناعي. يتيح التكامل مع مرجل استرداد مطحنة اللب ودورة البخار سهولة استرداد حرارة النفايات الكبيرة من العملية نفسها، بالإضافة إلى احتراق المخلفات الصلبة والغازية. يشير التحليل الاقتصادي إلى ربحية OFP من EWRs غرامة من الطاحونة. تم الحصول على قيمة حالية صافية أعلى، ولكن فترة استرداد أطول، لمصنع أكبر لإنتاج النفط النفطي الخارجي باستخدام المواد الأولية المشتراة. وجد أن الإنتاج المستقل غير مربح.

Abstract Coffee production in Brazil creates significant amounts of residues. The goals of this study are to evaluate the characteristics of these residues (parchment, husk, pulp, spent grounds, silverskin and defective beans); to discuss their potential for conversion to improved biofuels via thermochemical methods; and to develop mass and energy balances of the processes to help determine the value of residues for direct combustion, fast and slow pyrolysis, gasification, hydrothermal carbonization and torrefaction. Particularly the pulp, but also husk and parchment, are characterized by high moisture, as well as high contents of cellulose (41–64%) and hemicellulose (27–35%). These residues are suitable for several conversion routes, albeit with the drawback of drying need for the dry methods. The ash of these also creates a risk of fouling, corrosion and agglomeration with high-temperature and fluidized bed technologies. The silverskin and some of the defective beans are available at lower moisture. The spent coffee grounds appear a particularly advantageous residue for energy use: while moisture varies, the roasted product dries easily and has the highest heating value of the residues. For defective beans, little thermochemical treatment data is available. Among the technologies, for wet feedstocks hydrothermal carbonization has the advantage of post-conversion drying. Gasification appears advantageous for parchment with a high syngas yield and heating value. Fast pyrolysis of biomass suffers from the oxygen content of the liquid, requiring additional treatment; slow pyrolysis may be more appropriate. In conclusion, coffee residues have potential as feedstocks for a number of thermochemical conversion processes.

Abstract In this work, the production viability, physical, chemical and mechanical properties of briquettes produced from mixtures of coffee shrub residues and pinewood, were evaluated. The densification was carried out under constant operating conditions (temperature of 120 °C, pressure of 8.27 MPa) in a piston-press type laboratory-scale briquetting machine. Coffee shrub residues were mixed with pinewood in ratios of 25%, 50% and 75%. In addition, reference briquettes of pure pinewood and of each type of coffee shrub residue were produced. To characterize the raw material, ash content, volatile matter, fixed carbon together with the calorific value of produced samples, were measured. To characterize the suitability of the briquettes produced: apparent density, energy density, tensile strength, and equilibrium moisture content were determined. The highest values of energy density (19133–19899 MJ m−3), tensile strength (415–569 kgf), apparent density (1107–1163 kg m−3) and favorable values of equilibrium moisture content (9–11 wt %) were obtained from a mixing ratio of 75% of pinewood. The novel contribution of this research was to develop briquettes with appropriate physical and mechanical parameters from new raw materials that could serve as sustainable fuel sources for local firing systems.

Abstract The ore fines' pelletizing is an important part of iron mining, which ensures better use of natural resources and increases the blast furnace efficiency. However, this process consumes high amounts of non-renewable energy, such as natural gas (NG) and coke. Due to fossil fuel scarcity and global warming issues, at least partial substitution for renewable energy is desirable. Biomass gasification projects are being successfully developed in Northern Europe and large-scale circulating fluidized bed (CFB) biomass gasifiers have been commissioned. This work compares different technologies, such as CFB air and oxygen gasification, dual fluidized bed (DFB) steam gasification, and bio-synthetic natural gas (bio-SNG) production, focusing on the use of the product gas in an iron ore pelletizing process located in the Southeast of Brazil. The main parameters evaluated were flame temperature and gaseous flow rates. Economical evaluation was also performed. Air gasification provided a product gas with the lowest energy content but it was the most attractive investment. Oxygen gasification is apparently the best option as it provides a product gas with higher heating value at almost the same cost as air gasification. In both cases changes to the burners would be required. Bio-SNG could be utilized without any adaption in the indurating machine; however, it is still more expensive than NG.

The current global conditions provide the pulp mill new opportunities beyond the traditional production of cellulose. Due to stricter environmental regulations, volatility of oil price, energy policies and also the global competitiveness, the challenges for the pulp industry are many. They range from replacing fossil fuels with renewable energy sources to the export of biofuels, chemicals and biomaterials through the implementation of biorefineries. In spite of the enhanced maturity of various bio and thermo-chemical conversion processes, the economic viability becomes an impediment when considering the effective implementation on an industrial scale. In the case of kraft pulp mills, favorable conditions for biofuels production can be created due to the availability of wood residues and generation of black liquor. The objective of this article is to give an overview of the technologies related to the production of alternative biofuels in the kraft pulp mills and discuss their potential and prospects in the present and future scenario.

Abstract Iron oxide pellets are currently one of the main feedstocks in iron-making processes, and increasing over the years. They are mostly produced in moving-grate induration furnaces. Several mathematical models describing the pellet induration process have been published over the last 50 years. Despite being a topic of research for a long period, a relative small amount of journal papers is available in the main academic databases. In addition, the model assumptions have not changed considerably over time, regardless the development of faster computational tools. The purpose of this paper is to provide a review regarding the available mathematical models for travelling-grate iron ore induration furnaces, pointing at some opportunities and aspects to improve the accuracy of these models.