Determination of the activation energies of beef tallow and crude glycerin combustion using thermogravimetry

The present study deals with the determination of the activation energy for the thermal decomposition of two renewable fuels crude glycerin and beef tallow. The activation energies were investigated by using a thermogravimetric analyzer (TGA) in the temperature range of 25-600 degrees C in atmosphere of synthetic air. The TG curves of the thermal decomposition process of both samples were divided into several phases and the second, called PH2, was chosen for the kinetic study because it is associated with the combustion ignition. Differential Thermal Analysis (DTA) showed an endothermic event at the PH2 region for the crude glycerin corresponding to devolatilization, while for beef tallow, this step presented an exothermic event, called LTO (low-temperature oxidation), which is correlated with devolatilization followed by combustion. For the entire PH2, activation energy values for crude glycerin were between 90 kJ mol(-1) and 42 kJ mol(-1), while for the beef tallow they ranged from 50 kJ mol(-1) to 113 kJ mol (1). The activation energy values obtained at the pre-ignition stage - conversion between 0 and 0.45 - showed that the crude glycerin with higher values requires an additional energetic support at the start of combustion processes and the beef tallow ignites more easily, presenting lower values. According to the Wolfer's equation, a direct relation between the activation energy and the ignition delay is established and the results of this study provides useful data for the development and design of new combustion chambers and engines when non-traditional fuels are used as feedstock. (C) 2012 Elsevier Ltd. All rights reserved.CAPESCAPES [PNPD 0034088, BEX 1149/10-5]FAPESPFAPESP [2011/00183-2, 2011/11321-7

Study of the direct combustion of crude and technical glycerin as an alternative sustainable energy use

Nesta tese investiga-se e avalia-se a combustão direta da glicerina bruta e loira, co-produto e derivado, respectivamente, do processo de fabricação do biodiesel como alternativa de aproveitamento energético sustentável. Focaliza-se especialmente nos aspectos ambiental, técnico e econômico considerando as emissões, a transferência de calor associada e os aspectos operacionais como o eixo principal do estudo. Visa aumentar o conhecimento atual a respeito e contribuir para a melhoria das perspectivas da indústria do biodiesel e de uma parte da população. Para a combustão de glicerina bruta proveniente do processo de fabricação de biodiesel de sebo bovino desenvolveu-se um queimador tipo vórtice para glicerina bruta, avaliaram-se e quantificaram-se as emissões de óxidos de enxofre e nitrogênio, monóxido e dióxido de carbono, hidrocarbonetos totais, formaldeído, acetaldeído e acroleína, sendo também avaliados os efeitos mutagênicos potenciais dos gases produzidos. Da mesma forma foi estudada a composição físico-química, poder calorífico, decomposição térmica e a transferência de calor associada, além dos parâmetros operacionais da combustão, entre eles, a relação ar-combustível, temperatura de chama adiabática e o desempenho geral do processo para diferentes coeficientes de excesso de ar. Os ensaios foram desenvolvidos utilizando-se uma fornalha flamo tubular dotada de 12 câmaras calorimétricas e totalmente instrumentada com sensores de temperatura e sondas para análise contínua de gases em analisadores automáticos, fornecimento e controle de água de resfriamento e sistema de captação de dados em tempo real. Adicionalmente aos requisitos do estudo, foi necessário o desenvolvimento de sistemas e equipamentos auxiliares como a unidade de acondicionamento e alimentação de glicerina bruta e métodos de filtragem. Paralelamente, os efeitos mutagênicos e tóxicos foram avaliados sobre o bio-sensor Tradescantia (Clone KU-20), adaptando câmaras de intoxicação e técnicas de análise biológica desenvolvidas previamente. Os resultados foram processados, avaliados e comparados com as emissões e comportamento observado durante a combustão direta do óleo diesel, constatando-se que a combustão direta de glicerina bruta é um processo viável e suas emissões de CO, NOx, \'SO IND.2\' e HCT foram em média 39%, 75%, 69% e 38% respectivamente menores do que as do óleo diesel, porém o material particulado emitido pela glicerina bruta, e ainda mais pela loira, foi várias vezes superior do que com óleo diesel. Do mesmo modo, o nível de acroleína detectado no gás de combustão de glicerina bruta (214 ppbv) aparentemente não representa perigo para a população. Igualmente a energia produzida a partir da glicerina bruta resultou 61% e 58% mais barata do que com óleo diesel e glicerina loira respectivamente em condições semelhantes. No entanto, certamente verificou-se que a combustão de glicerina bruta é um processo tecnicamente mais complexo quando comparado com a dos combustíveis convencionais e evidenciou-se a necessidade de fazer um controle adequado das partículas emitidas para avançar no desenvolvimento do processo. Desta forma o presente estudo constitui-se em uma fonte importante de informação sobre a glicerina bruta e outros combustíveis similares para autoridades ambientais, indústrias e pesquisadores.This thesis investigated and evaluated on the assessment of the direct combustion of crude and technical glycerin, by-product and derivative respectively of Brazilian biodiesel manufacture process, as an alternative of sustainable energy use. The main axis of the study were the environmental, technical and economical aspects, focusing in emissions, heat transfer and the operational parameters associated with the combustion of crude and technical glycerin. It aims to increase the knowledge on the matter and contribute to the improvement of the economic and environmental perspective of biodiesel industry and isolated populations. It was evaluated the combustion of crude glycerin from bovine tallow biodiesel and technical glycerin from soy biodiesel process. Due to commercial unavailability of a capable burner for burning glycerin, a swirl burner was developed for crude and technical glycerin combustion, but it was also used successfully in other alternative fuels as raw bovine tallow and diesel. Emissions of sulphur and nitrogen oxides, total hydrocarbons, carbon monoxide, carbon dioxide, formaldehyde, acetaldehyde and acrolein were analyzed and quantified. Similarly, the mutagenic potential of gases was evaluated, as well as the calorific power, thermal decomposition behavior, the associated heat transfer and fundamentals operational parameters such as adiabatic flame temperature, air-fuel ratio and others. A experimental technique for mutagenic and toxicological effects assessment of combustion gases was analyzed and standardized, as well as the calorific power, the associate heat transfer and fundamentals operational parameters. The study was developed using a fully instrumented flame tube furnace, a swirl burner, continuous gas analyzers, a chromatograph, a thermogravimetric analyzer, automatic data acquisition systems and other auxiliary equipment. The mutagenic potential of the combustion gases was studied on biosensor Tradescantia clone KU-20 assay, using chambers of intoxication and biological analytical techniques previously developed and others specially adapted. The results were compared with the performance of diesel at similar conditions and finding that the direct combustion of crude glycerin is a feasible process. In addition, the emissions of CO, NOx, \'SO IND.2\' and THC were 39%, 75%, 69% and 38% correspondingly smaller than those of diesel. The particulate matter emitted by crude glycerin combustion and even more, by technical glycerin, was several times higher than those emitted by the diesel. Also, the emission of acrolein detected in flue gas from crude glycerin (214 ppbv), apparently have not represents danger to the population. Simultaneously was observed that the energy produced from crude glycerin was 61% and 58% cheaper than the energy from diesel and technical glycerin respectively under similar conditions. But certainly, it was found that the crude glycerin combustion is a more complex process compared with the combustion of conventional fuels

ESTIMACIÓN DE LA HUELLA DE CARBONO DE FUENTES FIJAS INDUSTRIALES DE LA CIUDAD DE BARRANQUILLA

Se calcularon las emisiones de los contaminantes criterio (CO, NOx y SO2) y de los gases de efecto invernadero (CH4, N2O y CO2) de las fuentes fijas industriales de Barranquilla, para contribuir al conocimiento del estado actual de la ciudad en materia de calidad del aire y estimar la huella de carbono producida por estas fuentes. Se comenzó por la recopilación de la información suministrada por Barranquilla Verde en el Distrito de Barranquilla y otras fuentes; clasificando así los distintos equipos industriales en: Calderas, hornos, plantas generadoras, calentadores, calderines y equipos de otro tipo de proceso industrial, seguidamente se buscaron los catálogos de los equipos para  hallar el consumo de combustible promedio y los diferentes factores de emisión acorde a la quema de combustibles (Gas natural, madera, residuos de palma, diésel y carbón) con el fin de calcular los gases de efecto invernadero y los contaminantes criterios producidos por cada fuente fija, por último se estimó la huella de carbono gracias a los potenciales de calentamiento (PCA) y los gases de efecto invernadero calculados. Los resultados arrojaron un valor de emisión total correspondiente a 331.967,8 t/año de Dióxido de Carbono equivalente (CO2-eq) para las 26 industrias conocidas, este valor está distribuido entre los gases de efecto invernadero de la siguiente manera: 330.897,4 t/año de CO2 474,32 t/año de CH4 y 596,07 t/año N2O, también se puede resaltar que las calderas es el equipo de mayor emisión de estos gases; sin embargo para obtener un valor relacionado a todas las industrias matriculadas en la ciudad, se extendió el análisis al hipotético caso de que todas las 87 industrias puedan ser consideradas como un foco de emisión contaminante y además tengan la misma distribución que las 26 industrias evaluadas (En lo que respecta a las actividades económicas o su clasificación según el DANE), de esta forma se tuvo en cuenta el desarrollo de una extrapolación lineal para esta hipótesis, dónde se encontró que, en tal caso, la huella de carbono de todas las industrias de la ciudad de Barranquilla tendrían un valor cercano a 1’110.815,5 t/año de CO2-eq

The Mutagenic Potential Caused by the Emissions from Combustion of Crude Glycerin and Diesel Fuel

This study evaluated the use of crude glycerin as an alternative of energy generation to replace the traditional fuels. The Tradescantia stamen hair mutation assay (Trad-SH) was applied to study the mutagenic effects caused by the emissions generated in the direct combustion of diesel oil and glycerin in a flame tube furnace. Tradescantia inflorescences were exposed to gaseous emissions from the combustion tests in a fumigation chamber for 30-40 min. The analysis of variance and the Tukey test were applied to compare the differences between six test groups (intoxicated with emissions from glycerin and diesel oil combustion) and a control group. Only one glycerin group showed statistical differences (0.05), possibly due to the complexity of the burning process and impurities, besides the acrolein present in its emissions. The high heating value (HHV) of crude glycerin (25.5 MJ/kg) was lower than diesel oil (45.19 MJ/kg), but it was comparable to other fuels. Although the use of glycerin as a biofuel could be an important aspect to be considered, the results showed that the glycerin had a substantial mutagenic potential similar to that of diesel oil