Excessive consumption of fossil fuels and its negative global effects have resulted in increasing interest in biomass energy. This paper presents an experimental study on biomass gasification reactions in an internally circulating fluidized bed gasifier (ICFBG). This work uses compressed corn straw as the raw material and studies the influence of different factors (temperature, equivalent ratio (ER), catalyst, and S/B ratios) on gasification products, in which S/B ratios are defined as the ratios of the steam rate to the biomass feeding rate. The experimental results show that when the bed material is the coal ash residue and air is used as the gasification agent, an increase in temperature from 700 to 900 °C reduces the CO2 and CH4 contents, whereas the H2 and CO contents increase. When a gasification agent is air–steam and the temperature is maintained at 700 °C, with a gradual increase in the amount of steam supplied to the gasifier, the CO2 and H2 contents gradually increase. Besides, an increase in the temperature, S/B ratio, and mixing proportion of dolomite leads to a gradual decrease in the tar content as well as the proportion of light tar, while the proportion of heavy tar becomes relatively high. In addition, we obtained experimental data for an actual gasifier and conducted a brief comparative analysis with the ICFBG developed in this study. The results show that the data provided by the ICFBG developed in this study can serve as a reference and theoretical basis for the operation of actual gasifiers in power plants.

Biomass pyrolysis can be used to obtain clean fuels, such as liquids or gases, and is a promising approach to biomass energy utilization. Levoglucosan (LG) is an important product of biomass pyrolysis. The study of its thermal decomposition process is helpful for understanding the mechanisms underlying biomass pyrolysis.We investigated the decomposition of LG using a density functional theory method based on quantum mechanics. In this paper, we studied 23 possible reaction paths for LG pyrolysis to generate small molecular gases and 51 compounds (including reactants, intermediates, and products), and quantified the 47 transition states involved in the pathway. The optimal reaction path of CO 2 is ring opening / decarboxylation, with an energy span of 301 kJ mol À1 . The optimal reaction pathway for CO is dehydration / alcohol-ketone tautomerization / ring opening / decarbonylation, with an energy span of 286 kJ mol À1 . Therefore, it is theoretically simpler to produce CO from LG than to generate CO 2 . Moreover, by analysing the dehydration reaction in the pathway, we observed that dehydration is beneficial to the production of CO by LG, but is not conducive to the formation of CO 2 .

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Increasing discharge of sewage sludge is a threat to the ecological environment, and sludge treatment via combustion is the most feasible alternative. However, the low calorific value and high-water content of raw sludge results in poor firing performance and increases the risk of environmental pollution. Recently, co-combustion has emerged as a more environment-friendly technology. Herein, the combustion behaviours of sewage sludge, corn stalk and their mixture at four heating rates were studied via thermogravimetric experiments. Results yielded the division of weight loss into three stages for corn stalk: dehydration, combustion of volatiles and combustion of fixed carbon; four stages were identified for sewage sludge and the mixture of sludge and stalk: dehydration, combustion of volatiles, combustion of fixed carbon and thermal decomposition of a small amount of minerals. Synergistic analyses found that with a 60% blending ratio of sewage sludge, interaction between the components in the high-temperature range was greatly promoted. Gas emission characteristics showed that CO 2 was the main product during (co-)combustion, while the NO x emissions at low (or high) temperatures for the blend were higher (or lower) than the theoretical values. Temperature had little effect on H 2 S emissions, though it significantly affected SO 2 emissions during co-combustion. V CS gas emissions when CS is burned SS E 60% actual amounts of released gas with sludge blending ratios of 60% SS C 60% theoretical amounts of released gas with sludge blending ratios of 60%

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