Modeling of the Process of Thermochemical Decomposition of Plant Waste in the Activated Carbon Production Line

Abstract

Today, there is a tendency toward an increase in the release of plant waste, which, with classical methods of disposal, leads to adverse environmental effects. The paper presents the results of mathematical modeling of the process of thermochemical decomposition of plant waste for a technological line for the production of activated carbon, designed to partially solve the problem of waste disposal. At the Department of Processing of Wood Materials of the Kazan National Research Technological University (KNRTU), a plant for the pyrogenetic processing of plant materials into activated carbon has been developed. Thermochemical decomposition of plant materials is a complex thermodynamic process in which a large number of chemical reactions occur with the absorption and release of heat. The process of pyrolysis of plant raw materials can be divided into three zones: pre-drying, thermochemical decomposition, and coal calcination. Each of these zones has its own differential equations. To optimize the modes of the activated carbon production process, there is a need for numerical modeling of the process of thermochemical decomposition of plant raw materials, since the quality of the obtained coal directly affects the adsorption capacity of the produced adsorbent and the percentage of impurities in the finished product. Numerical modeling produces as output the numerical values of the density; the heat of the chemical reaction in the process of splitting and polymerization of the constituent components of the plant raw materials and the temperature of the material in the process; the thermochemical decomposition; and the dependence of the duration of the thermochemical decomposition process on the thickness of the bulk layer and the size of the processed particles. Mathematical modeling is carried out by jointly solving the system of differential equations of thermochemical kinetics, expressed for an infinite plate. Pine chips 7 mm thick are taken as the object of the research.