Simulation and experimental research on uniform heating of roller-hearth furnace with oxygen-enriched pulse combustion

In order to achieve sustainable development of the ceramic industry, it is necessary to ensure the quality of product firing under the premise of energy saving and consumption reduction. This study presents the development of an oxygen-enriched pulse combustion test system for roller kilns, designed to regulate the flow of fuel and combustion gas at varying oxygen concentrations (21 %, 24 %, 27 %, and 30 %) using a continuous wave function. The pulse combustion tests, which involved multiple variations in amplitude and period, were complemented by simulations of the flow and temperature fields within the kiln using Ansys Fluent. The results demonstrated that the highest energy savings were achieved at an oxygen concentration of 30 %, with reductions of approximately 52 % and 36 % in energy consumption during the warming and constant temperature phases, respectively. Under conditions of low amplitude and long period (A = 30, T = 135), the temperature uniformity of the JFCC thermos block within the furnace was improved by 55 %. The pulsed combustion process was found to extend the diffusion period of the return vortex, thereby increasing the strength of the vortex ring and enhancing the churning capability of the kiln airflow. Oxygen-enriched pulse combustion facilitated the distribution of heat from localized high-temperature zones throughout the furnace by increasing the period and decreasing the amplitude, thereby reducing temperature stratification. This study effectively addresses the issue of uneven temperature distribution caused by oxygen-enriched combustion in roller kilns.