Study On Heating And Stirring Mode Of Vertical Mixing Device For Reclaimed Asphalt Pavement

In China,a significant number of roads are currently undergoing maintenance and repair,resulting in the production of large quantities of old asphalt mixtures each year.Disposing of these materials has a substantial impact on the environment.As China’s environmental protection requirements continue to increase,road maintenance and regeneration technologies have received greater attention.In the on-site hot recycling repair vehicle for asphalt pavement,the vertical heating and stirring device is a critical component that mainly functions to stir and heat the mixture.However,current research focuses primarily on horizontal mixers,with insufficient attention given to vertical mixers.Moreover,during operation,vertical mixers have issues with high energy consumption and uneven heating of the mixture.Therefore,this study takes the vertical heating and stirring device designed by a collaborative enterprise as the research object.Based on simulation and experimental results,the heating and stirring parameters were determined,and corresponding heating and stirring modes were established to improve production efficiency and quality while reducing the energy consumption of the maintenance equipment.This paper presents a theoretical analysis of the structure,heating system thermal balance,and particle motion during stirring for a vertical heating and stirring device to improve its heating efficiency and mixing uniformity.The study identifies that hot air temperature,velocity,and heating time are the main factors affecting the heating efficiency of the mixed material during operation,while stirring time and speed are the primary factors influencing mixing uniformity.To investigate the effects of these factors on the device’s operation,a simulation model is established based on the device’s structure to analyze the impact of parameters such as hot air temperature,velocity,and heating time on the heating effect of the mixed material.An intermittent heating mode is proposed,and its temperature distribution proportion and temperature rise characteristics are simulated and optimized.The new heating mode’s effectiveness is verified through experiments.In addition,using the discrete element theory and EDEM software,the stirring process is simulated,and the degree of mixing uniformity is characterized by the discrete coefficient of the fine aggregate in the mixed material.By analyzing the effects of stirring time and speed on the discrete coefficient and combining it with the particle’s motion,a variable-speed stirring mode is proposed and simulated to ensure mixing uniformity.Combining the intermittent heating and variable-speed stirring modes,a new heating and stirring mode is proposed.Compared with the conventional stirring mode,this new mode has lower energy consumption,shorter operation cycles,and higher production efficiency,providing a reference for improving equipment efficiency and quality while reducing energy consumption.