Valorization of semi-solid by-product from distillation of cellulosic ethanol into blends for heating and power

Abstract

Burning down on semi-solid by-product from distillation of cellulosic ethanol to power upstream steps of its manufacturing is usual. However, this feedstock is homogenous in size and shape, hygroscopic and poorly energetic. These disadvantages make its re-use in the industrial plant very complex. Conversion of this agro-residue into high-performance blends for heating and power is, accordingly, the scientific point of this study. The pilot-scale manufacturing of composite pellets consisted of systematically pressing the residue with sugarcane bagasse at the mass ratios of 1:4, 2:4, and 3:4 on an automatic pelletizer machine at 200 MPa and 125 °C. The process of compaction lasted for 90 s. Durability and energy density, both increased significantly, from 95.85% to 99.55% and from 27.95 GJ m−3to 32.20 GJ m−3 with blending at 3:4. Practically, the semi-solid by-product considerably improved the feeding, thus, enabling the layers of particles to go smoothly through the channel-forming die of the machine. Thereby, blends became stiffer and denser than pellets purely consisting of sugarcane bagasse. Preliminary evidence of the process of pelleting capable of highly valorizing the semi-solid by-product from distillation of cellulosic bioethanol into mechanically stable and energetically effective hybrid fuel grade biosolids exist. The major findings of this paper should be of great relevance to ensure safe and effective transportation and storage of biomass in indoor facilities where the risk for the generation of dust and fines and the subsequent off-gassing and self-firing is high. Furthermore, pelletization may optimize the co-generation of heat and steam at the large-scale bioethanol station.