Use of coffee (Coffea arabica) pulp for the production of briquettes and pellets for heat generation

Abstract

Coffee bean (Coffea arabica) processing generates high amount of residues that are sources of environmental pollution. Therefore, an appropriate solution is needed. The objective of this study was to determine the potential of coffee pulp to produce briquettes and pellets. The study included pulp drying (using air, solar and hot air methods); the production of briquettes and pellets; the evaluation of their energy, physical and mechanical properties; and the evaluation of pellet quality using X-ray densitometry. The results showed that the pulp presented an initial moisture content of 90%, resulting in drying times of 699, 308 and 55 hours for air, solar and hot air drying, respectively, and the calorific values of the pellets and briquettes were 12,501 kJ kg -1 and 11,591 kJ kg -1 , respectively. The ash content was 8.68% for the briquettes and 6.74% for the pellets. The density of the briquettes was 1,110 kg m -3, compared with 1,300 kg m -3 for the pellets. The apparent densities were 1,000 kg m -3 and 600 kg m -3 for the briquettes and pellets, respectively, and the water absorptions by the briquettes were 7.90% and 8.10% by the pellets. The maximum horizontal compression effort was 26.86 kg cm -2 , measured in the pellets, compared with 4.52 kg cm -2 in the briquettes. The maximum horizontal load was 93.24 kg, measured in the briquettes, compared with 33.50 kg in the pellets. The value of the pellet durability test was 75.54%. X-ray densitometry showed that the pellet was uniform and a few cracks were observed on the pellet surface.Index terms: Coffee residues, drying, coffee processing, biomass, bio-resources. RESUMONo processamento dos grãos de café (Coffea arabica) ocorre o problema de geração de grandes quantidades de resíduos não utilizados pela indústria, tornando-se uma fonte de poluição ambiental. Portanto, é necessária a busca de soluções para atender a este problema de geração de resíduos. O objetivo do trabalho foi determinar a possibilidade de utilização da polpa dos grãos de café processados para a fabricação de briquetes e pellets. A pesquisa compreendeu a secagem da polpa dos grãos de café (pelo meio do ar, solar e ar aquecido); a manufatura de briquetes e de pellets; a avaliação das suas propriedades como fonte de energia e propriedades físicas e mecânicas e a determinação da sua qualidade pela metodologia de densitometria de raios X. Os resultados mostraram que a umidade inicial da polpa de café foi de 90% e o tempo de secagem foi de 699, 308 e 55 horas no ar, secagem solar e por ar quente, respectivamente. O poder calórico foi de 12 501 kJ kg -1 e de 11 591 kJ kg -1 de pellets e de briquetes, respectivamente; o teor de cinzas foi de 8,68% e de 6,74% para os briquetes e os pellets, respectivamente. Em relação às propriedades físicas, a densidade dos briquetes foi de 1.110 kg m -3 e dos pellets de 1.300 kg m -3 a densidade aparente dos briquetes foi 1.000 kg m -3 e de 600 kg m -3 dos pellets e a absorção de água de 7,90% dos briquetes e 8,10% e dos pellets. Finalmente, o esforço de c...

Review: Utilization of Waste From Coffee Production

“…Similarly to coffee husks, coffee pulp has been studied to be reused for mushroom production (30,31), composting (32), biogas production (33), bioethanol production (34), converted into fuel briquettes or pellets (35), enzymes production such as pectinases or cellulases (36,37), and also for food production (converts coffee pulp into a nutritious flour, which can be used for baking or cooking, or even as an addition to smoothies, soups, or sauces) (38).…”

Valorisation of the Residues of Coffee Agro-industry: Perspectives and Limitations

“…The residual heat may be used to dry out more coffee. The use of coffee pulp for the production of briquettes and pellets for heat generation has recently been proposed [14]. The study included pulp drying (using air, solar and hot air methods); the production of briquettes and pellets; the evaluation of their energy, physical and mechanical properties; and the evaluation of pellet quality using X-ray densitometry.…”

The Feasibility Study of Physicochemical Properties of Sarawak Liberica sp. Coffee Pulp

“…The skin and pulp of the coffee beans will be removed and become the residues as they are not needed to process the coffee. As there a wide world production of coffee, it will associate with ecological damages as the residues of coffee can lead to environmental pollution if it is not handled well (Cubero-Abarca et al, 2014). Most of the coffee pulp is dumped into a landfill or river stream directly during wet processing without proper handling of waste (Geremu et al, 2016).…”

“…Most of the coffee pulp is dumped into a landfill or river stream directly during wet processing without proper handling of waste (Geremu et al, 2016). The absence of a method that can utilize the use of coffee by-product is one of the main problems to use the coffee pulp for biomass productions due to the high moisture content (Cubero-Abarca et al, 2014). However, due to the myriad problems such as disposal problems of this by-product and cause environmental pollution, this material has received greater attention compared in the past.…”