Abstract
Investigation of the processes of thermal decomposition of biofuels components is needed for increasing production efficiency and energy specifications of biofuels, including composite ones. During recent years in the field of bioenergy, these circumstances have led to a greatly increased interest in the thermal characteristics of biomass of various origins, including the kinetic patterns of its thermal destruction. The purpose of this paper is to determine the kinetic parameters of desorption of physically bound moisture and to determine activation processes of non-isothermal decomposition of hemicelluloses of wood and plant biomass, peat and composite mixtures, using the non-isothermal kinetics method. The work provides an analysis according to the Broido kinetic model of the thermal destruction of biofuel samples selected over the territory of Ukraine. The method allows to determine the effective parameters of the kinetics of the individual stages of samples decomposition based on the analysis of the thermogravimetric dependences of biomass decomposition and to calculate the kinetic characteristics of the thermal destruction that proceeds according to the reaction mechanism of the order of n ≤ 1. The results of calculation of kinetic parameters for the stages of desorption of physically-bound moisture and thermal decomposition of hemicelluloses are presented. The value of the activation energy of moisture desorption for biomass is in the range of 51.5-59.4 kJ/mol, the average value is 56.5 kJ/mol; the maximum deviation of the activation energy for different types of biomass does not exceed 4.7%; for peat the activation energy is 43.50 kJ/kg, which is 23% below the average value for biomass. The calculated values of the kinetic constants of the thermal decomposition of hemicelluloses vary considerably. So for peat the average value of the activation energy corresponds to 37.0 kJ/mol. For biomass these values range from 75 to 104 kJ/mol, the average value is 90.8 kJ/mol; the maximum deviation of the activation energy for different types of biomass does not exceed 12%. It has been established that the use of composite mixtures based on peat and biomass allows, for high-temperature drying or heat treatment, to separate the temperature ranges for decomposition of hemicellulose and cellulose, thereby ensuring the thermal decomposition of predominantly low-calorie constituents of hemicellulose without significant loss of calorie constituent of the fuel. The results of the performed studies can be used in the calculation of processes and installations associated with the thermal preparation of the studied fuels. Key words: biofuel, biomass, peat, composite fuel, activation energy, non-isothermal kinetics method, Broido model.
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call