Evaluación de la combustión de briquetas de mezclas de residuos sólidos en calefactores a leña.
Loading...
Date
2025
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
La crisis ambiental derivada del uso de combustibles fósiles y la alta contaminación atmosférica por material particulado asociada a la calefacción residencial a leña en Chile, hacen imperativa la búsqueda de alternativas energéticas sostenibles. En este contexto, la valorización de residuos agroindustriales, específicamente cuescos de palta y borra de café (SCG), surge como una oportunidad para desarrollar biocombustibles sólidos que impulsen la economía circular. El objetivo general de este trabajo es evaluar la combustión de briquetas fabricadas a partir de mezclas de estos residuos sólidos en calefactores a leña, analizando su eficiencia energética y las emisiones generadas para determinar su viabilidad frente a la leña tradicional.
Para llevar a cabo la investigación, se diseñaron y fabricaron briquetas cilíndricas con orificio central y briquetas cilíndricas macizas, utilizando dos formulaciones distintas de mezclas de cuesco de palta, SCG y aserrín, empleando almidón de yuca como aglutinante. La metodología incluyó la caracterización fisicoquímica de las materias primas y la determinación experimental del Poder Calorífico Superior (PCS) mediante una bomba calorimétrica. Posteriormente, se realizaron ensayos de combustión en una cocina a leña a escala de laboratorio, donde se registraron perfiles de temperatura, consumo de combustible y se cuantificaron las emisiones de gases (CO, NOx) y Material Particulado (MP) utilizando un analizador de gases y un tren de muestreo isocinético, respectivamente.
Los resultados principales indicaron que las briquetas poseen un potencial energético competitivo, las mezclas A y B alcanzaron un PCS de 16,31 MJ/kg y 17,04 MJ/kg respectivamente, valores muy cercanos a los 17,31 MJ/kg obtenidos para la leña certificada. Sin embargo, en términos ambientales, las briquetas no superan a la leña, presentan mayores emisiones de CO en la fase de brasas (8.000–14.000 mg/m³ vs 4.000–5.800 mg/m³ en leña), confirmando la relación inversa entre estabilidad térmica y generación de CO. Asimismo, las emisiones de NOx dependen de la composición del combustible, La briqueta A, con mayor contenido de nitrógeno (0,52 vs 0,09), genera valores más altos y persistentes (350–500 mg/m³), mientras que la leña mantiene un perfil más estable y con menores emisiones. En cuanto al MP, la leña es el combustible más limpio (29 mg/m³ y 8,05 g totales), mientras que la Briqueta B es la más contaminante (30,2 g, ≈4 veces más que la leña). La Briqueta A se ubica en un punto intermedio, pero aún emite el doble que la leña (16,18 g).
Se concluye que, si bien es posible producir briquetas con propiedades energéticas comparables a la leña incorporando residuos de palta y café, su implementación actual genera mayores emisiones contaminantes en calefactores convencionales. Estos hallazgos sugieren que, para viabilizar su uso como alternativa sostenible, investigaciones futuras deben enfocarse en mejorar la densidad de compactación, una selección de residuos diferentes y optimizar los equipos de combustión para mitigar las emisiones de MP, CO y NOx.
The environmental crisis resulting from the use of fossil fuels and the high atmospheric pollution caused by particulate matter associated with residential wood heating in Chile makes the search for sustainable energy alternatives imperative. In this context, the valorization of agro-industrial residues, specifically avocado pits and spent coffee grounds (SCG), emerges as an opportunity to develop solid biofuels that promote the circular economy. The general objective of this work was to evaluate the combustion of briquettes manufactured from mixtures of these solid residues in wood stoves, analyzing their energy efficiency and the emissions generated to determine their viability compared to traditional firewood. To carry out the research, cylindrical briquettes with a central hole were designed and manufactured using two different formulations of mixtures of avocado pits, SCG, and sawdust, employing cassava starch as a binder. The methodology included the physicochemical characterization of the raw materials and the experimental determination of the Higher Heating Value (PCS) using a bomb calorimeter. Subsequently, combustion tests were conducted in a laboratory-scale wood stove, where temperature profiles, fuel consumption, and emissions of gases (CO, NOx) and Particulate Matter (PM) were recorded using a gas analyzer and an isokinetic sampling train, respectively. The main results indicated that the briquettes have competitive energy potential: mixtures A and B reached PCSs of 16,31 MJ/kg and 17,04 MJ/kg, respectively, values very close to the 17,31 MJ/kg obtained for certified firewood. However, in environmental terms, the briquettes did not outperform firewood, exhibiting higher CO emissions during the char phase (8,000–14,000 mg/m3 vs. 4,000–5,800 mg/m3 in firewood), confirming the inverse relationship between thermal stability and CO generation. Furthermore, NOx emissions depended on fuel composition; Briquette A, with a higher nitrogen content (0.52% vs. 0.09%), generated higher and more persistent values (350–500 mg/m3), while firewood maintained a more stable profile with lower emissions. Regarding PM, firewood was the cleanest fuel (29 mg/m3 and 8.05 g total), while Briquette B was the most polluting (30.2 g, approx 4 times more than firewood). Briquette A stood at an intermediate point but still emitted double that of firewood ($16.18 g). It is concluded that, although it is possible to produce briquettes with energy properties comparable to firewood by incorporating avocado and coffee residues, their current implementation generates higher pollutant emissions in conventional wood stoves. These findings suggest that, to make their use viable as a sustainable alternative, future research should focus on improving compaction density, selecting different residues, and optimizing combustion equipment to mitigate MP and NOx.
The environmental crisis resulting from the use of fossil fuels and the high atmospheric pollution caused by particulate matter associated with residential wood heating in Chile makes the search for sustainable energy alternatives imperative. In this context, the valorization of agro-industrial residues, specifically avocado pits and spent coffee grounds (SCG), emerges as an opportunity to develop solid biofuels that promote the circular economy. The general objective of this work was to evaluate the combustion of briquettes manufactured from mixtures of these solid residues in wood stoves, analyzing their energy efficiency and the emissions generated to determine their viability compared to traditional firewood. To carry out the research, cylindrical briquettes with a central hole were designed and manufactured using two different formulations of mixtures of avocado pits, SCG, and sawdust, employing cassava starch as a binder. The methodology included the physicochemical characterization of the raw materials and the experimental determination of the Higher Heating Value (PCS) using a bomb calorimeter. Subsequently, combustion tests were conducted in a laboratory-scale wood stove, where temperature profiles, fuel consumption, and emissions of gases (CO, NOx) and Particulate Matter (PM) were recorded using a gas analyzer and an isokinetic sampling train, respectively. The main results indicated that the briquettes have competitive energy potential: mixtures A and B reached PCSs of 16,31 MJ/kg and 17,04 MJ/kg, respectively, values very close to the 17,31 MJ/kg obtained for certified firewood. However, in environmental terms, the briquettes did not outperform firewood, exhibiting higher CO emissions during the char phase (8,000–14,000 mg/m3 vs. 4,000–5,800 mg/m3 in firewood), confirming the inverse relationship between thermal stability and CO generation. Furthermore, NOx emissions depended on fuel composition; Briquette A, with a higher nitrogen content (0.52% vs. 0.09%), generated higher and more persistent values (350–500 mg/m3), while firewood maintained a more stable profile with lower emissions. Regarding PM, firewood was the cleanest fuel (29 mg/m3 and 8.05 g total), while Briquette B was the most polluting (30.2 g, approx 4 times more than firewood). Briquette A stood at an intermediate point but still emitted double that of firewood ($16.18 g). It is concluded that, although it is possible to produce briquettes with energy properties comparable to firewood by incorporating avocado and coffee residues, their current implementation generates higher pollutant emissions in conventional wood stoves. These findings suggest that, to make their use viable as a sustainable alternative, future research should focus on improving compaction density, selecting different residues, and optimizing combustion equipment to mitigate MP and NOx.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Mecánico/a.
Keywords
Madera Combustión, Briquetas, Calefactores, Contaminación atmosférica