Control and supervision of the aluminium electrolysis process with expert system.

摘要

The electrolytic cell is the central element of the aluminum electrolysis. In spite of the automatic control systems applied to run the aluminum electrolytic cells, a significant amount of information about the status of the cells is still not involved in the decision making process. Moreover, the quality of the decision depends on the operator in charge.; A two-level rule-based expert system is built which incorporates the available “operator” and “engineer” expertise. This expert system is designed to serve both a generalized as well as a particular type of cell. It can work in either off-line or on-line mode. When in on-line mode, the process data can be accessed via a network and a cell simulator can also be connected to test the expert system-based process monitoring and alarm management. The proposed expert system assists the operators to make a detailed analysis of the cell's state, to detect faults, and to conduct trend analysis or a long-term target assignment. The expert system can also be a reference for the adjustment of the set points by control system engineers.; The knowledge base design is intended to expand the application to the various types of cells and to facilitate a system update. For this reason, the structure of the knowledge base and the reasoning strategy are designed with some unique characters.; This thesis provides the acquired knowledge about the aluminum electrolysis process and relevant areas. It consists of the general domain knowledge for the knowledge engineering as well as the special knowledge for particular types of cells. It also describes the construction of the expert system and shows some examples with detailed discussions of the cell diagnosis.