Effect of Microwave Pre-Treatment of Biomass on the Thermal Oxidative Conversion of Biomass Blends Containing Pre-Treated and Raw Biomass of Different Origination in Terms of Processing Rate and Heat Production

In this paper, the thermochemical conversion of selectively pre-treated binary blends composed of 30% microwave (MW) pre-treated biomass pellets (wheat straw, wood) and 70% of different origin raw biomass pellets (wheat straw, wood, or peat) was performed using originally developed experimental device with a heat output up to 20 kW. Biomass pellets were pre-treated at temperatures of 200 and 275 °C using a microwave laboratory scale torrefaction of the original construction. It was established that synergistic effects of interaction between the components of binary blends promote an increase in the efficiency of their thermochemical conversion by 5.8–9.4%. It was assumed that synergistic effects of thermochemical conversion can be related to an increase in surface area and porosity of pre-treated pellets. With a focus on different steps and rates of biomass degradation and heat amounts released for different types of blends, the thermal analysis (DTG/DSC) of ground blends in the temperature range of 25–650 °C was performed in air media with the heating rate of 10 °C/min. According to the thermal analysis data, the heat energy yield of ground blends meets the requirements of linear regression based on the additivity principle and the development of synergistic effects during thermochemical conversion of ground blends was not detected.