Advanced Process Control In Aluminum Atomization And Powder Classification

With widespread use of aluminum powder in many fields of national economy, the modern industry has more requests to process control of aluminum powder manufacture. In this paper, a advanced control system for the process of aluminum atomization and powder classification is designed based on the specific need of a production line of a fine aluminum powder manufacturer. Automation and intelligence in the production are achieved.In this paper, based on in-depth analysis of the production process of nitrogen atomization, the start-stop mode of all the equipments, overrun alarm and emergency shut down of each subsystem are developed to ensure the security of the system. In order to solve the problem of nitrogen flow fluctuation and coupling interference in the process of classification, main pipeline flow rate is controlled by fuzzy-PID, which makes the flow rate return to set value quickly after significant interference and maintain a high steady-state accuracy. A method aiming at avoiding unwanted fluctuations of total air volume and maintaining the valve on the main pipeline at the large degree of opening is researched. After the analysis of the factors affecting the secondary air flow, neural network PID control with a predictive model is designed, reducing the interference on the secondary air flow from pipe coupling and total air volume. The oxygen content is controlled by subsection control, which ensures that the oxygen content is less than the alarm value. A cascade control on pipeline pressure is designed to decrease the interference from the balance tank.The production line is controlled by Siemens S7-400H redundant PLC and redundant industrial personal computers. All slave stations communicate with PLC through redundant PROFIBUS. The structure of multi-layer redundancy ensures the reliability. The programs in PLC and supervising system are accomplished by Step7and WinCC respectively. The result of field operation shows that the control system has high control accuracy, high stability and friendly man-machine interface. It meets the need of aluminum powder manufacture via nitrogen atomization method, contributing to the economic benefit of the enterprise.