Research On Airflow Field Simulation And Coal Movement Characteristics In Cement Kiln

Rotary kiln is the core equipment of the cement production process. In the cement production process, the raw material from the kiln tail experience different reactions in different function region with the cooperation of primary air and secondary air and the burner flame. The raw material finally turn to clinker and unloaded from the kiln hood.This paper derived from the key project "large scale rotary kiln energy-saving technologies and applied research" from Hunan Science and Technology Department and based on a new dry cement kiln with production of2500tons per day in Hunan province. The following achievements have been made in the aspect of airflow field and coal movement features in cement kiln.The grid model of four-air channel pulverized coal burner-cement kiln was established through the Gambit pre-processor and the three-dimensional numerical simulation of airflow field in cement kiln was carried out by Fluent fluid software, which verified the superiority of the RNG k-ε model to deal with rotary kiln Swirl problem. From the research of airflow distribution in cement kiln, influence on the main recirculation zones caused by the changes of the main process parameters of burner is analyzed and turbulent kinetic energy distribution of airflow was showed. simulated result of the airflow field can provide reference for reasonably controlling pulverized coal combustion.A research in the motion trail of the pulverized coal particles as well as their movement velocity along the motion path was conducted with the coupling calculating of the airflow and the pulverized coal particles. Then the effect that different pulverized coal particle size and coaling have on the residence time of the pulverized coal particles was analyzed. In addition, the distribution of the pulverized coal in the cooling zone and firing zone of the kiln was researched. It turned out that more pulverized coal particles gathered in the region of kiln axis and less near the kiln wall. It is this kind of distribution that is benefit for the formation of good flame.The temperature of cement kiln cylinder was monitored in Industry field. The result of the experiment turned out to be identical with the simulated result of the airflow field and pulverized coal distribution. Thus the reliability of the flow model and the particle model was proved.