Abstract : Rotary kilns are large-scale equipment in the aluminum industry and have long used DC speed control systems. This paper proposes a scheme using a variable frequency speed control device as the control system to achieve simultaneous control of the main unit current, cooler current, and flame temperature, based on the actual characteristics of rotary kiln control. Practice shows that the system can automatically correct parameters and track loads during operation, ensuring that the system and load are in optimal working condition. Keywords : Rotary kiln, frequency converter, PLC 1 Introduction The rotary kiln designed by the Carbon Department of Qinghai Aluminum Plant is a large-scale piece of equipment in the plant, mainly used in the calcination section for calcining delayed petroleum coke (12% ash content). For many years, this equipment has used a single-chip microcomputer-controlled DC speed control system, and the quality of this speed control system directly affects the service life, product quality, and output of the rotary kiln. Therefore, based on the actual characteristics of rotary kiln control, we propose a scheme using a variable frequency speed control device as the control system to achieve simultaneous control of the main unit current, cooler current, and flame temperature. [b]2 Working principle of rotary kiln 2.1 Process flow[/b] The material is continuously fed to the kiln tail by the feeder. It moves slowly towards the kiln head as the kiln body rotates. During the process of moving from the kiln tail to the kiln head, it is first preheated in the preheating zone, and then calcined in the high temperature zone of 1250-1300℃. The calcined material falls into the cooler at the bottom from the feed pipe at the kiln head. The material stays in the kiln body for about 68 minutes. 2.2 Temperature control The temperature of the calcination zone of the rotary kiln is controlled at 1250-1300℃. The factor affecting the calcination quality of the rotary kiln is temperature. The factors affecting the calcination temperature are mainly the matching of fuel and air volume, the magnitude of negative pressure, the amount of feed and the speed of material movement. (1) The effect of material movement speed in the kiln on temperature The material movement speed in the kiln has a great influence on the calcination quality and production capacity of the rotary kiln. If the calcined material moves too fast within the kiln, its residence time is too short, resulting in insufficient heating and poor calcination quality. Conversely, if the movement speed is too slow, calcination losses will increase, reducing the rotary kiln's production capacity. The material's movement speed is related to factors such as the kiln's inclination, internal diameter, rotational speed, cross-section of the material layer, and the central angle of the kiln center. [b][align=center]For more details, please click: Application of Frequency Converters in Carbon Rotary Kiln Control Systems[/align][/b]