Comparative Analysis of Characteristics Based on Three Processes of Kenaf Solid Fuel: Hydrothermal Carbonization, Torrefaction, and Low Ash Torrefaction

This study compared kenaf-based solid fuel characteristics using three processes: hydrothermal carbonization (HTC), torrefaction (TOR), and low-ash TOR, (LA_TOR). Solid fuels were produced by conducting the ash removal process at 50 °C for 60 min in an autoclave, followed by HTC or TOR at various temperatures (160, 200, 240, 280, and 320 °C) for 60 min. The resulting products' chemical compositions and fuel properties were then compared. The study found that under HTC at 320 °C, the product had the highest carbon content compared with the products from TOR and LA_TOR at 320 °C. Thus, HTC produced the highest-quality solid fuel of the three methods. However, this process showed a low energy yield and significant energy loss. In contrast, LA_TOR exhibited a high energy yield, low energy loss, and effectively reduced the ash content of the product. This demonstrates its suitability for industrial-scale applications that demand fuel with low ash content and energy loss.