Method and apparatus for controlling the heat balance in aluminum reduction cells

摘要

A method and apparatus are provided for maintaining a predetermined energy balance in a device, such as an aluminum reduction cell. The apparatus includes a relatively short and thin heat flow sensor having a first and second thermocouple located within opposite closed ends of a hollow thermally conductive body. Each thermocouple is composed of two wires of the same dissimilar metals. The sensor is secured by one closed end of the sensor body to an outside surface of the wall member to extend substantially perpendicular to the location on the wall without significantly affecting the heat flow from the wall surface being measured. A first wire of each thermocouple is of the same metal for electrically connecting the junctions of each thermocouple. The second wire of each thermocouple extends to a location intermediate the closed ends of the sensor body and is electrically connected to an instrument responsive to the electrical potential between the first and second thermocouples. A control means uses the electrical signal to determine the heat flow through the wall member as a function of the temperature difference between the thermocouples and to maintain a predetermined energy balance of the system by adjusting the amount of energy added to the system. The method and apparatus also control the frozen lateral ledge thickness of an aluminum reduction cell.