Nonisothermal Thermogravimetric Kinetic Investigations on Combustion Behaviors of Concomitant Biomass from Urban Plants

Abstract

Thermogravimetric combustion characteristics of white poplar leaves, pine needles, poplar leaves, ginkgo leaves, and corn straw in air were tested under different heating rates. The results indicated that the combustion process of biomass consisted of at least two independent reactions, while the number of reactions was related to the properties of components in biomasses. In addition, the corresponding temperature of the maximum reaction rate on reaction rate curves shifted into higher temperature zones with increasing heating rate, which was due to the insufficient transfer of heat under a high heating rate. Meanwhile, the reaction rate curves were separated into independent peaks and then fitted with three kinetic models. It was found that the combustion of biomass samples followed the volume model in the early stage and then obeyed the random pore model in the last stage. Namely, the influence of thermodynamic conditions is more significant for the pyrolysis of selected biomasses, while the combustion of residual carbon depends on kinetic conditions. Moreover, the evolution of functional group structures in biomasses during combustion showed that aliphatic hydrogen and C=C bands were stable at the early stage, while aromatic hydrogen was observed to be more stable during the whole combustion process. The fluctuation in proportion of −CH3 was insignificant for new radicals of −CH3 that were formed during the decomposition of aromatic and aliphatic hydrocarbons; however, the overall decreasing trend indicated the gradual shrink in length of aliphatic branches with the extending of combustion.

Research on the Combustion Performance of Municipal Solid Waste in Different Sorting Scenarios: Thermokinetics Investigation via TG–DSC–FTIR–MS

“…The peak temperature of the sample increased with the increase of the heating rate, which was common in nonisothermal heating, mainly due to the thermal lag phenomenon. 8,23 At a low heating rate, the temperature gradient between the particles was small, and the temperature difference between the inside and the outside of the particles was small, 24 forming a good heat transfer from the surface to the inside. On the contrary, at a high heating rate, a relatively higher temperature gradient made the temperature difference between the inside and outside of the particles larger, resulting in a lag in the reaction.…”

“…Thermogravimetry analysis (TGA) was used to study the combustion process of MSW, which was helpful to analyze the combustion mechanism and obtain the kinetic parameters. , The components of MSW and the heating rate were the main factors affecting the combustion process and product properties of MSW . The main thermal reaction temperature of MSW components was concentrated in the range of 150–500 °C, but the thermal stability properties of different components were quite different. − According to TG analysis of typical components, it was found that food residue presented multiple peaks below 320 °C, printing paper presented the main peak at 350 °C, and polyethylene (PE) and polypropylene (PP) presented a very strong peak at 455 to 485 °C . In addition, the ignition difficulty of MSW components was ranked in the order of kitchen waste < wood, bamboo < paper < fabric < plastic.…”