Limo He

Influence of different demineralization treatments on physicochemical structure and thermal degradation of biomass.

To study the catalytic role of alkali and alkaline earth metallic species and eliminate their negative impact during biomass thermal utilization, different leaching methods have been applied in numerous experiments. Thus it is necessary to investigate the potential influence on biomass physicochemical structure using different agents. Rice straw was selected to study the demineralization impact on physicochemical structure and pyrolysis characteristics. It is shown that strong acid leaching exhibited higher removal efficiency of minerals, but it introduced more notable impact on physicochemical structure of biomass comparing to water and weak acid leaching. Different leaching methods give chance to study catalysis characteristics of intrinsic metals on biomass thermal reaction. Contrast to alkaline earth metals especially Ca hindering thermal decomposition, alkali metals promoted this reaction obviously. In addition, comparing to physicochemical structure changes created by leaching process, the influence of removal of minerals played the dominant role in biomass thermal behavior.

Interaction and kinetic analysis for coal and biomass co-gasification by TG-FTIR.

This study aims to investigate the interaction and kinetic behavior of CO2 gasification of coal, biomass and their blends by thermogravimetry analysis (TG). The gas products evolved from gasification were measured online with Fourier Transform Infrared Spectroscopy (FTIR) coupled with TG. Firstly, TG experiments indicated that interaction between the coals and biomasses mainly occurred during co-gasification process. The most significant synergistic interaction occurred for LN with SD at the blending mass ratio 4:1. Furthermore, thermal kinetic analysis indicated that the activation energy involved in co-gasification decreased as the SD content increased until the blending ratio of SD with coal reached 4:1. The rise of the frequency factor indicated that the increase of SD content favored their synergistic interaction. Finally, FTIR analysis of co-gasification of SD with LN indicated that except for CO, most gases including CH3COOH, C6H5OH, H2O, etc., were detected at around 50-700°C.

Effects of inherent alkali and alkaline earth metallic species on biomass pyrolysis at different temperatures

This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H2 and C2H4 was increased and that of CO2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water-gas shift reaction, and enhanced the yield of H2 and CO2. Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals.

Kinetic models comparison for steam gasification of coal/biomass blend chars

The non-isothermal thermogravimetric method (TGA) was applied to different chars produced from lignite (LN), sawdust (SD) and their blends at the different mass ratios in order to investigate their thermal reactivity under steam atmosphere. Through TGA analysis, it was determined that the most prominent interaction between sawdust and lignite occurred at the mass ratio of sawdust/lignite as 1:4, but with further dose of more sawdust into its blends with lignite, the positive interaction deteriorated due to the agglomeration and deactivation of the alkali mineral involved in sawdust at high steam gasification temperature. Through systematic comparison, it could be observed that the random pore model was the most suitable among the three gas-solid reaction models adopted in this research. Finally, rational kinetic parameters were reached from these gas-solid reaction models, which provided a basis for design and operation of the realistic system of co-gasification of lignite and sawdust in this research.