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Process synthesis for coffee husks to energy using hierarchical approaches

Dal-Bó, Vanessa, Lira, Taisa, Arrieche, Leonardo, Bacelos, Marcelo
Renewable energy 2019 v.142 pp. 195-206
Coffea canephora, biomass, coffee beans, drying, electric power, energy conversion, hulls, pyrolysis, renewable energy sources, wastes
The aim of this research was to optimize technological applications of biomass waste to obtain energy using both the heuristic and the evolutionary methods. Six steps for the generation of energy were studied with the option of energy integration in the drying and chemical reaction sub-systems. The waste used was the husks of Robusta coffee beans resulting from two distinct treatments, the wet and dry ones. The structural synthesis characterized by branch-and-bound trees resulted in 3780 plausible flowsheets to be analyzed for the four waste-to-energy technologies approached. Experimental studies allowed identification of fundamental characteristics to define the embryonic flowsheet to the process. The heuristic rules made it possible to point out pyrolysis as a promising technology regarding the energy conversion of coffee husks. The finding primary flowsheet, nº89, become an economic alternative for generation of electric power from coffee husks. Moreover, impacts of neighbor flowsheets on energy conversion were also analyzed and discussed.