Modeling and Studying the Cooling of Waste Tire Solid Pyrolysis Products

Every year, 1.5 billion tires are produced around the world, and each of them eventually falls into the waste stream. The growing volume of waste tires and limited possibilities for their disposal generate the need to develop methods for recycling them. A review of papers addressing the waste tire recycling problem with the use of proposed mechanical and thermochemical processing methods is presented. It is shown that researchers take interest in pyrolysis as a technology for thermochemical conversion of waste tire to produce valuable products: a solid fraction represented by coke residue (carbon black), a liquid hydrocarbon fraction (pyrolysis oil), and non-condensing gaseous fraction (pyrolysis gas). In a number of published papers, focus is placed on improving the consumer properties of each fraction. Conditions under which the coke residue quality can be improved to the level of activated carbon are, and methods for implementing this are developed. The cooling of solid pyrolysis products can be a limiting factor for the pyrolysis plant operation. Unloading of the coke residue at increased temperatures with outdoor cooling can lead to its burning out. To develop an efficient coke residue cooling heat exchanger, it is necessary to know the physical properties of this substance. A method for determining the thermal conductivity of fine coke residue based on the use of physical and mathematical modeling of the cooling process has been developed and implemented. Experiments on studying the coke residue bed cooling process in air in the temperature range from 500 °C to the ambient temperature were carried out. The time dependences of temperature at several points of the bed layer are obtained. A measuring chamber mathematical model reproducing the experimental conditions is developed. By studying the model, it is possible to determine the coke residue thermal conductivity, which approximates the calculated cooling process temperature curves to those obtained in the experiment with satisfactory accuracy. Based on the analysis of experimental data, two temperature ranges are identified, and a linear dependence of the bed thermal conductivity on the temperature is found in each of them. The coefficients of these functions are determined by minimizing the response function using the Box--Wilson method. The obtained results are used for the development of industrial thermal power engineering facilities.