Comparative analysis of characteristics based on three processes of kenaf solid fuel: Hydrothermal carbonization, torrefaction and low ash torrefaction

Abstract

Abstract This study conducted three processes—hydrothermal carbonization (HTC), torrefaction (TOR) and ash removal, and low ash TOR (LA_TOR)—to compare the characteristics of kenaf-based solid fuel under different production processes. To produce solid fuels, the ash removal process was conducted 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 chemical compositions and fuel properties of the resulting products were then analyzed and 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, out of the three methods, HTC produced the highest quality solid fuel. However, this process exhibited a low energy yield and large energy loss. In contrast, LA_TOR showed a high energy yield and low energy loss, and effectively reduced the ash content of the product, demonstrating its suitability for industrial-scale applications that require fuel with LA content and energy loss.