Mathematical Model of Optimum Control for Petroleum Coke Production in a Rotary Tube Kiln

A method for investigating the temperature stability of crude and modified commercial petroleum coke and the results of studies were presented. The TG/DSC method was used for the experimental study of the calcination of petroleum coke and characterization of coke improved as a result of oxidation. It was found that commercial coke still contained significant amounts of volatile residues. The high-temperature stability of commercial coke used for electrode production (e.g., in furnaces for silicon production) or in carbothermal processes can be improved by its additional annealing under certain conditions in a tube kiln or electric calcinator. Coke calcination was modeled using the results of thermal analysis and formal kinetics. An approach was proposed for determining the critical particle size of the given coke taking into account the spatial inhomogeneity due to thermal conductivity. It ensures uniform calcination throughout the particle to ensure uniform annealing throughout the entire volume of the material in the kiln, which makes it possible to use a quasi-homogeneous model. Using the kinetic model of the reaction and data on the maximum admissible size of coke particles, the operation of a rotary tube kiln was modeled to determine the optimum conditions of its operation in the production of coke with specified characteristics: the optimum temperature profile of the material along the length of the kiln and the rate of material in the kiln. The amount of ash in the coke was evaluated to be nearly zero, which makes this coke especially valuable for metallurgical production.