IMPROVING THE ANODE BAKING PROCESS BY ESTIMATION OF THE ANODE TEMPERATURE

摘要

Although the anode temperature is the most relevant parameter in the baking process, this parameter is not used to control the process. The first reason for this is that the response time of the anode temperature is so slow that it cannot be used as a direct control of the burners or of the flue gas volume. The second reason is that the life of the anode thermocouple (TC) is so short, that the monitoring of all pits would incur tremendous costs. Finally, if an anode TC is used, only one point of the pit, which, normally, is not the most critical, can be observed. Here, a method is presented which solves all three disadvantages of conventional measurement. The method is based on an adaptive dynamic model which uses the flue temperature as an input. It allows us to calculate the temperature at any point of the pit, using only a few parameters. After a single basic identification, these parameters are adapted during a test period in one or two preheat sections which are equipped with an anode TC for each pit. Since the identification is carried out in the low temperature range and with a few TC's only, the handling is minimal and the TC's suffer no real wear. So, at any point in time, a prediction of the final temperature at any point in the pit, and a modification of the firing profile to ensure sufficient temperature at the coolest point of the pit can be achieved. This allows a minimum top temperature for a desired quality and gives lowest energy and refractory cost.