Self-Heating of Agricultural Residues During Storage and Its Impact on Fuel Properties

Abstract

The present work aimed to investigate the self-heating process of agricultural residues during storage and to evaluate its impact on the properties of the stored fuels. Two types of biomass, rice straw and husk, were used as raw materials. Their self-heating processes and characteristics were investigated by storing the materials with different moisture contents and particle sizes in a bench-scale reactor and monitoring the evolution of inside temperatures. The resulting materials were systematically characterized. Comparison of the composition, calorific value, pH value, surface structure, and combustion characteristics between the initial and stored materials were performed to assess the influence of moderate self-heating on the fuel properties. Observations on the evolution of the temperatures inside stored materials showed that the characteristics of the self-heating process including the induction time, period with significant heat generation, and peak temperature as well as the hottest position within the sample depend upon biomass type, initial moisture content, and particle size of the sample. Characterization of fuel properties showed that moderate self-heating during storage slightly changed the proximate composition of dry biomass but resulted in considerable losses of dry matter and energy as well as a slight increase in the fuel combustion reactivity. The higher moisture contents and smaller particle size benefit self-heating. Rice straw is more prone to self-heating than rice husk under the same conditions, as reflected by the higher extent of the self-heating and the more dry matter and energy losses.

The Flame-Retardant Mechanisms and Preparation of Polymer Composites and Their Potential Application in Construction Engineering

“…Ying et al [ 136 ] also studied the preparation of straw magnesium cement (SMC) from rice straw, another bio-based isolation material. In addition, studies have proven that rice straw is easier to self-heat than rice husk, which triggers the occurrence of spontaneous combustion in biofuels [ 137 ]. This difference is caused by chemical composition, physical properties, bulk density and surrounding environment.…”

Characterizing Variability in Lignocellulosic Biomass: A Review

“…For example, oxidation and microbial degradation during storage can produce more C−O groups on carbohydrate surfaces. 210 (2) At the macromolecule level, the bond formation and cleavage taking place during storage, and preprocessing can cause condensation of the macromolecules. For example, lignin tends to migrate and condense when the attached hemicellulose is removed by dilute acid pretreatment.…”

“…The physical properties of biomass feedstocks emerge from their underlying macromolecular interactions, which can undergo substantial changes across multiple length scales during the harvest, storage, and preprocessing and conversion processes: (1) At the subnanometer level, the functional groups on carbohydrates and lignin can be significantly modified during storage and pretreatment. For example, oxidation and microbial degradation during storage can produce more C–O groups on carbohydrate surfaces . (2) At the macromolecule level, the bond formation and cleavage taking place during storage, and preprocessing can cause condensation of the macromolecules.…”

Signatures of Biologically Driven Hemicellulose Modification Quantified by Analytical Pyrolysis Coupled with Multidimensional Gas Chromatography Mass Spectrometry

“…The seasonal biomass supply requires a storage process to ensure the year-round availability. However, depending on moisture content, bale storage could present favorable conditions for microbial growth, biological heating, and biomass degradation, which results in feedstock loss, quality changes, and risks to downstream conversion processes and worker health and safety. Field studies have observed that the aged biomass generated by storage can reduce bale integrity. , Biological heating can alter composition and cell wall structures that are manifest in macro-scale mechanical properties.…”