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Biomass is a promising resource for the production of renewable energy, liquid fuels, and chemicals. Microwave pyrolysis is one of the directions of multifunctional conversion of raw materials. In the present work, the effect of microwave power on the characteristics of sawdust pyrolysis is studied. With an increase in power, the maximum yield of combustible gases increased, and a large proportion of the total pyrolysis time included the useful time for the release of gases. An increase in power affected the yield of individual gases non-linearly and on a different scale. The average yield of CO and CO2 remained practically unchanged when the microwave power was increased from 840 to 1760 W. However, with a further increase in power to 2200 W, there was a significant increase in the average yield of CO and CO2 (2.5 and 1.4 times, respectively). An increase in power by 2.6 times contributed to an increase in the average yield of CH4 by 5 times and H2 by 3.8 times. The increased power of microwaves contributed to the degassing of wood and intensification of secondary pyrolysis reactions, which resulted in a decrease in the mass of the solid residue by 5.3 times and a decrease in the liquid product yield by 2.7 times. A comprehensive analysis using MCDA showed that an increase in energy costs with an increase in microwave power is integrally compensated by an improvement in pyrolysis performance. So, when the power was varied from 840 W to 2200 W, the pyrolysis efficiency indicator increased by 1.3–2.2 times, considering the growth in energy consumption. [ABSTRACT FROM AUTHOR]

The paper presents the results of experimental research into lab-scale microwave pyrolysis of wood biomass. The influence of the surface area and the structure of the biomass layer on the characteristics of pyrolysis during microwave heating are discussed. We have established that the biomass layer structure and surface area have a significant effect on the yield of pyrolysis gas. The approach of creating artificial deformation of the biomass layer was tested. The elements of artificial porosity made it possible to increase the CO yield by 18% and 32% compared to the pyrolysis of a biomass layer with artificial channels and a uniform layer, respectively. The concentration of H2 was 33% higher compared to the layer without artificial pores and 3% lower compared to artificial channels. The yield of CO2 increased by 25%, and the yield of CH4 doubled. The experiments showed that the distribution of biomass on a half of the bottom of the crucible and the additional porosity of the biomass layer surface effectively increase the yield of the pyrolysis gas components. Recommendations for increasing the efficiency of microwave pyrolysis of biomass were formulated. [ABSTRACT FROM AUTHOR]

This paper describes the results of an experimental investigation on the stages of thermochemical transformation of fuels prepared from waste. We studied the combustion of coal slime and its co-combustion with additives (waste turbine oil, sawdust, and rapeseed oil). The mass fraction of the additive was 5%. Fuels in the forms of a pellet, dry loose layer, and slurry were heated in a tubular muffle furnace. The reactivity of the fuels was evaluated, and the duration of the main process stages was recorded. Experiments have shown that it is more expedient to burn coal slime in combination with other components, which improved the ignition and burnout performance of the blends. The addition of turbine oil accelerated the flame combustion by 3–6 times. Rapeseed oil reduced the duration of the endothermic stage by 50–60%. The slurry droplets had the longest pre-flame stage. Their burnout was more intense than that of pellets or a layer and was less dependent on the temperature in the furnace. The longest burnout was typical of pellets. The data obtained are essential in planning and conducting industrial tests on the energy recovery of coal slime, biomass, and refined products. [Display omitted] • Combustion of coal slime is advisable in combination with other components. • The burnout of slurry droplets is the best in comparison with pellets and layers. • The addition of turbine oil (5 wt%) reduced the endothermic period by 3–6 times. • Minimal ignition temperature of waste-derived blends varied from 450 °C to 500 °C. • Coal slime pellets tend to low reactivity and incomplete burnout. [ABSTRACT FROM AUTHOR]