Dynamic insights into combustion drivers and responses of water hyacinth: Evolved gas and ash analyses

Abstract

Non-food biomass feedstocks owing to their advantages have come to the forefront as the efforts have been intensified to develop cleaner energy sources and technologies in the face of global climate change. This study aimed to dynamically characterize the combustion drivers and responses including the gas emission and ash deposition risks for roots (WHR) and stems and leaves (WHSL) of water hyacinth. Their combustion processes consisted of the four sequential stages of the water evaporation, the combustions of volatiles and fixed carbon, and the degradation of minerals. The WHR combustion had a higher total heat release (2140.6–4226.7 J/g) than did the WHSL combustion (1255.6–3110.6 J/g). In terms of the Flynn-Wall-Ozawa method, the average activation energy was estimated at 167.42 and 172.41 kJ/mol for WHR and WHSL, respectively. The reaction mechanisms of the volatiles and fixed carbon combustion stages were best elucidated by the F1 (f(α) = 1- α) and F3 (f(α) = (1- α)3) models for WHR and the F3 (f(α) = (1- α)3) and F1.5 (f(α) = (1- α)1.5) models for WHSL, respectively. CO2 was the main evolved gas for both WHR and WHSL and exhibited the fastest response to temperature. Evolved S-containing gases (SO2 and COS) (0.13% for WHR and 0.12% for WHSL) were extremely low. The WHSL ash had a higher risk of slagging and fouling than did the WHR ash. Our findings can provide insights into the cleaner and optimal production of the water hyacinth combustion.