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The content of cellulose, hemicellulose, and lignin in plant biomass varies. The volume and composition of the synthesis gas obtained from two-stage pyrolysis depend on the feedstock. This study aimed to investigate the feasibility of predicting the two-stage pyrolysis characteristics based on the constituent composition of a biomass. Three commercially available components, two real biomass samples, and two synthetic mixtures were studied. Thermogravimetric analysis and one-stage and two-stage pyrolysis of each material were performed. The pyrolysis behavior of real and synthetic biomass samples was compared with predicted characteristics based on the performance of the components and their proportion in the mixture. Different behaviors of the three components during one-stage and two-stage pyrolysis were observed. The composition of the synthesis gas during two-stage pyrolysis agreed well with the calculated values. The overall yield of synthesis gas from real biomass was consistent with that predicted and obtained from synthetic mixtures. [ABSTRACT FROM AUTHOR]

This document explains the advantages and disadvantages of three types of bed materials used in two-stage pyrolytic processing of wood waste into the synthesis gas. The process combines pyrolysis and subsequent high-temperature heterogeneous cracking of volatiles in the carbon residue fixed bed (obtained by raw material pyrolysis), the inert material (aluminum oxide ceramics) or dolomite. Experimental data characterising the dependence of the gas yield, its chemical composition, the calculated lower heating value and tar content on the process parameters are presented. The optimisation of parameters and the bed material mostly depends on the process purpose: a large-volume inert material bed is preferable for using in burners in the cracking zone, it allows to obtain the most calorific gas with a lower calorific value up to 13 MJ / m³; whereas a carbon residue at a temperature of above 1,010 °C is a preferable bed material in gas engines (when the tar content is less than 50 mg/m³); and a carbon residue at a temperature less than 1,000 °C is the best for the synthesis of liquid fuels (H2 to CO ratio reaching its maximum). Using dolomite turned up to be impractical because of its thermal instability and high amount of both CO2 and H2O in the gas product. [ABSTRACT FROM AUTHOR]