STUDY OF THERMOCHEMICAL CONVERSION OF ORGANIC SUBSTANCES USING AN EQUILIBRIUM MODEL

Abstract

The processes of thermal conversion of wood in a combined layer gas generator are considered. The processes of gas generation and pyrolysis are distinguished. The generally accepted approach provides the description of such processes by means of different models. The mentioned processes do not have sharp boundaries and when external influences change can smoothly change one into the other. The problem arises of describing the process at such an interface. Different models at the transition boundary of one process may define different compositions of reaction products for the same process parameters. A model based on equilibrium chemical reactions uniformly describing pyrolysis and gasification processes is proposed. To demonstrate its capabilities while minimizing computational costs, only the case of oxygen blowing with wood of different moisture content is considered. The proposed model allows taking into account both the formation of the gaseous phase of the thermodestruction products of the feedstock and the condensed phase in the form of a charcoal residue (charcoal). The calculation results are compared with the experimental data of various authors. One of the peculiarities of the experimental data given in the literature is the wide scatter of their values for the same initial conditions. The proposed model allows us to build a platform for their uniform explanation. Increasing the list of possible chemical reactions in the model will make it possible to study combustion, pyrolysis and gasification processes under a unified approach. The possibility of taking into account the presence of a condensed phase in reaction products and the expansion of the model will make it possible to: investigate the process of thermal degradation of various organic substances, including household waste, use different oxidizing agents, take into account different ways of introducing additional external energy. The consequence of extending the model will be an increase in the number of equations in the system of algebraic non-linear equations and, consequently, some complication of its solution.