Production and Characterization of Low-Ash Empty Fruit Bunches Pellets as a Solid Biofuel

• Published in: Bioenergy research 2022-03, Vol.15 (1), p.517-529
• Main Authors: Nasrin, Abu Bakar, Loh, Soh Kheang, Sukiran, Mohamad Azri, Bukhari, Nurul Adela, Aziz, Astimar Abdul, Lim, Joseph, Lim, Stephen, Chin, Eddy
• Format: Article
• Language: English
• Subjects: Ash removal; Biofuels; Biomass energy; Biomedical and Life Sciences; Bulk density; Calorific value; Chlorine; Drying; Fibers; Fruits; Hardwoods; Life Sciences; Lignocellulose; Pelleting; Pellets; Physicochemical properties; Plant Breeding/Biotechnology; Plant Ecology; Plant Genetics and Genomics; Plant Sciences; Raw materials; Size reduction; Wood Science & Technology
• ISSN: 1939-1234; 1939-1242
• DOI: 10.1007/s12155-021-10316-x

In searching for lignocellulosic-based alternative pellets, quality is key, ash in particular, for market acceptance and penetration. One such feedstock of growing importance, pressed empty fruit bunches (EFB) fibres, was exploited in this study via 3 different physical pretreatment methods (Tests 1–3) prior to pre-pelletising in an industrial-scale plant for improving the ash content. The ash removal effects on quality of resultant pelletised EFB (in terms of fuel and physicochemical properties) were assessed and compared with commercial pellets based on available standards. The combined sieved and water sprayed feedstock (Test 3), 1.60 wt.% ash content (pre-pelletising), yielded EFB pellets with correspondingly better ash quality (1.58 wt.%, post-pelletising) than the sieved only (Test 2) option, 2.78 wt.% and 3.63 wt.%, and the untreated (control, Test 1), 4.07 wt.% and 4.66 wt.%, respectively. Besides, all the pretreated feedstocks/biopellets exhibited much improved proximate and ultimate properties, bulk density and calorific value (≤ 18 MJ kg −1 ) after pre-pelletising/pelletising steps due to size reduction and drying. Both treatments (Tests 2–3) were able to produce lignocellulosic-based EFB pellets with fuel properties comparable to non-wood pellets, except for durability index (≤ 95%) and chlorine content (> 0.2 wt.%). In terms of wood pellets, Test 3 showed an advanced quality for ash compliance and reduction of unwanted ash-inducing elements, chlorine and potassium in particular, with > 40% removal efficiency. Henceforth, the combined sieving and spray water washing physical treatment of a high-ash lignocellulosic biomass offers an immediate low-hanging approach for practical utilisation and improvement of ash-related fuel properties of commercial solid biofuels.