Agriculture waste, a great opportunity to produce energy and high value products: experience in Colombia.

Colombia has high potential from various sources such as fast growing plantations, municipal waste, and sludge from wastewater treatment plants, forest residues and agricultural harvesting. Those sources are considered biofuels of the second generation, which can contribute significantly to the replacement of the currently used fossil energy carriers for transportation fuel production and they can be precursors of new products with high-added value. In this work we show different experiences carrying out in Colombia related to thermochemical process to produce Bio-oil, Bio-char and Syngas. We show the results of our experience in slow and fast pyrolysis consisting of thermal decomposition of the lignocellulosic material in an inert atmosphere or with oxygen shortage (less than stoichiometric), at temperatures between 500 °C - 600 °C, with particle sizes between 0.5mm - 2mm, with the aim of producing a liquid fuel with a high oxygen content, called bio-oil, a solid residue ‘’bio-carbon’’ or char and non-condensable gases with low calorific value (rich in CO, CO2 CH4, H2) which they can be re-circulated in the reactor to supply heating power. Depending on the operating conditions of the reactor, pyrolysis can be classified as: slow pyrolysis and fast pyrolysis (see Figure 1). Please click Additional Files below to see the full abstract

La irreversibilidad: hoja de ruta que marca el destino de los procesos naturales

Resumen: La presente monografía se ha organizado de tal manera que el lector podra encontrar en varias partes del texto algo que 10 Iteva a reflexionar sobre la irreversibilidad yes por eso, que se tiene un capitulo introductorio en donde se presenta manifestaciones naturales de la irreversibilidad con preguntas que motivaron la ejecucion de este trabajo. Posteriormente, sigue un capitulo destinado a comprender de que esta constituida la naturaleza y se menciona algo de las diferentes estrategias 0 teorias que dan elementos para su comprension de los aspectos fundamentales de la mecanica clasica, cuantica y la ffsica estadistica. Luego, se conduce al lector para que se sumerja en uno de los eventos naturales de mayor trascendencia que es el movimiento Browniano, el cual permite la conexion de las fluctuaciones con la disipacion y por ende explicar causas de la irreversibilidad y desde el punto de vista practico, el teorema Fluctuacion-Disipacion es una estrategia para medir propiedades fisicas de la materia. Finalmente, se presenta una disertacion relacionada con uno de los teoremas recientemente analizados y relacionado con la fluctuacion, el cual permite superar el vado que dejo la teorfa de Boltzmann cuando dio por primera vez una explicacion torica de la irreversibilidad y al mismo tiempo creo las famosa formula para la cuantificacion de la entropia (S=kaLnQ) que es el escrito que aparece en la lapida colocada en la tumba de famoso cientificoAbstract: This monograph is organized so that the reader may find in various parts of the text rather than 10 Iteva to reflect on why yes irreversibility, which has a introductory chapter which presents natural manifestations of irreversibility with questions that led to the execution of this work. Then follows a chapter aimed at understanding that this constituted nature and mentioned some of the different strategies 0 theories that give items to your understanding of the fundamentals of classical mechanics, quantum and statistical ffsica. Then he leads the reader to dive into one of the most significant natural events is Brownian motion, which allows the connection of fluctuations in dissipation and thus explain causes of irreversibility and from the point of view practice, the fluctuation-dissipation theorem is a strategy for measuring physical properties of matter. Finally, we present a dissertation related to one of the theorems recently analyzed and related to the fluctuation, which overcomes the ford to let Boltzmann theory when the first gave an explanation of irreversibility-ring and while I think the famous formula for the quantification of the entropy (S = kaLnQ) which is the writing that appears on the headstone placed at the tomb of famous scientis

Transport and Mixing in Liquid Phase Using Large Eddy Simulation: A Review

Many mixing processes in engineering applications are turbulent. At high‐Schmidt regime, the scalar scales are much lower than those of the velocity field, making difficult instantaneous measurements and direct numerical simulation for studying systems of practical interest. The use of large eddy simulation (LES) for analyzing transport and mixing of passive and reactive scalars at high‐Schmidt (Sc) regime is addressed in this article. We present two different approaches for studying scalar transport and mixing in LES: the conventional approach is based on the modeling of the unclosed subgrid‐scale scalar flux term in the filtered scalar equation by models commonly used for high‐Sc flows. The second approach presented in this review for dealing with high‐Sc flows is based on the use of a filtered mass density function (FDF) of the scalar field. Conclusions are presented about the relative merits of the two approaches

Evaluation of the effect of torrefaction and slow pyrolysis on porosity and adsorption performance of biochar and activated carbons obtained from palm kernel shell

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CO2 participation in cross-linking reactions and char formation during bio-oil pyrolysis

The integration of new CO2 capture and storage technologies into energy generation processes has led to the development and study of the oxy-fuel combustion, in which the nitrogen in the air is replaced by recirculated CO2 that facilitates its capture and storage to reduce polluting emissions. Currently, the integration of oxy-fuel technologies with the use of new fuels such as bio-oil obtained from the pyrolysis of biomass is a topic of interest. In this case, the CO2 content surrounding the bio-oil droplets modifies the pyrolysis mechanism due to barriers in the diffusion of light volatiles at low temperatures (less than 200°C) and formation of char as a result of the cross-linking reactions [1] explained by the hydrolysis of the heavy fraction of bio-oil is restricted in this atmosphere. Please click Additional Files below to see the full abstract

Physicochemical Phenomena in the Roasting of Cocoa (Theobroma cacao L.)

The quality of cocoa depends on both the origin of the cacao and the processing stages. The roasting process is critical because it develops the aroma and flavor, changing the beans’ chemical composition significantly by chemical reactions induced by thermal energy. Aspects have been identified as the main differences between bulk cocoa and fine cocoa, the effect of time and temperature on the formation of the flavor and aroma, and the differences between conductive heating in an oven, convective with airflow, and steam flow. Thermal energy initially causes drying, then non-enzymatic browning chemical reactions (Maillard reaction, Strecker degradation, oxidation of lipids, and polyphenols), which produce volatile and non-volatile chemical compounds related to the flavor and aroma of cocoa roasted. This review identified that the effect of the heating rate on the physicochemical conversion of cocoa is still unknown, and the process has not been evaluated in inert atmospheres, which could drastically influence the avoidance of oxidation reactions. The effect of particle size on the performance of product quality is still unknown. A more in-depth explanation of energy, mass, and chemical kinetic transfer phenomena in roasting is needed to allow a deep understanding of the effect of process parameters. In order to achieve the above challenges, experimentation and modeling under kinetic control (small-scale) are proposed to allow the evaluation of the effects of the process parameters and the development of new roasting technologies in favor of product quality. Therefore, this work seeks to encourage scientists to work under a non-traditional scheme and generate new knowledge

Uso de energía en la producción de panela en Colombia (análisis exergético)

RESUMEN: El objetivo de este estudio es determinar cómo se usan los recursos energéticos en la producción de panela en Colombia. Para este fin, se realizaron mediciones en ocho trapiches que representan los procesos productivos típicos de la panela. Con los datos experimentales se obtuvieron los balances de primera y segunda ley de la termodinámica, a partir de los cuales se calcularon las eficiencias y algunos indicadores del uso de la energía. La comparación de los trapiches mostró que las mejoras tecnológicas permiten aumentar la eficiencia energética a niveles aceptables debido a un mejor proceso de combustión y a la reducción de las pérdidas energéticas asociadas con los gases de escape y la transferencia de calor a través de las paredes. El efecto de dichas mejoras sobre la eficiencia de segunda ley no es significativo, lo cual sugiere que se deberían implementar sistemas de cogeneración en los procesos de producción a gran escala con el fin de hacer un uso más racional de los recursos energéticos.ABSTRACT: The aim of this study is to determine how energy resources are used in the production of unrefi ned sugar in Colombia. To do this, measurements were carried out in eight sugar mills that represent the typical production processes for unrefi ned sugar. These data were used to obtain fi rst and second law balances, which were then used to calculate effi ciencies and some energy use indicators. By comparing the mills it was found that technological improvements enable energy effi ciency to be increased to acceptable levels due to better combustion processes and reductions in energy losses from exhaust gases and heat transfer to the walls. The effect of these improvements in second law effi ciency is not signifi cant, which suggests that cogeneration systems should be implemented in large-scale production processes in order to make a better use of the energy resources

Kinetic Studies on Cocoa Roasting Including Volatile Characterization

Despite roasting being the most crucial step in cocoa manufacture, its thermochemical effects on cocoa are not entirely understood. This work aims to understand the kinetics and chemical composition of the volatile compounds formed during roasting. The weight loss of two sizes of cacao powder was evaluated in thermogravimetric analysis (TGA) with five heating rates (10 to 180 °C min-1), using air and nitrogen as the carrier gas. A global Friedman isokinetic model was used to obtain kinetic data from the TGA measurements. For this, seven different stages were discriminated, and the kinetics were determined for each stage separately. PTV-GC-MS identified the gas phase, and SPME-GC-MS quantified the volatile compounds trapped in the solid phase. At intermediate temperatures (150 to 250 °C), aromatics (e.g., pyrazines, aldehydes, ketones, phenols, and pyrroles) are formed and transferred to the gas at higher temperatures for a prolonged time. Typical Maillard and Strecker degradation reaction products in both gas and solid phases were identified and used to set up a reaction network for cocoa roasting

Viabilidad comercial para la siembra de caucho y la extracción competitiva del látex en el departamento de Córdoba

Desarrollar una investigación que establezca la viabilidad comercial de cultivos de caucho y extracción de látex en el Departamento de Córdoba con el fin de suplir la limitada oferta que se presenta hoy en el mercado nacional. Dicho estudio considerará las condiciones agrícolas propias de las tierras cordobesas, de los agricultores y de la economía local tratándose de cultivos de tardío rendimiento.Introducción. Marco teórico. El mercado de caucho natural y del látex en Colombia. Oportunidades del negocio de extracción de látex y sus diferentes formas comerciales. Viabilidad comercial de implantar cultivos de caucho en el Departamento de Córdoba. Conclusiones. Recomendaciones. Referencias. Tabla de gráficos. Tabla de tablas.Administrador de EmpresasPregrad