Control of a melting process

Abstract

The invention relates to a method to control a process for heating or melting a metal, in particular aluminium, which includes: heating said metal in a fuel-fired furnace wherein a fuel is combusted with an oxygen containing gas, measuring the concentrations of carbon dioxide and oxygen in the furnace atmosphere, calculating the theoretical concentration of oxygen in the furnace atmosphere on the basis of said concentration of carbon dioxide, determining the difference between said theoretical concentration of oxygen and said detected concentration of oxygen and controlling said process depending on said difference.

1 . Method to control a process for heating or melting a metal, in particular aluminium, comprising:
 heating said metal in a fuel-fired furnace wherein a fuel is combusted with an oxygen containing gas,   measuring the concentrations of carbon dioxide and oxygen in an atmosphere of the furnace,   calculating a theoretical concentration of oxygen in the furnace atmosphere on the basis of said concentration of carbon dioxide,   determining a difference between said theoretical concentration of oxygen and said concentration of oxygen detected and   controlling said process depending on said difference.   
   
   
       2 . Method according to  claim 1 , wherein said oxygen and said carbon dioxide concentration are continuously measured. 
   
   
       3 . Method according to  claim 1 , wherein said fuel-fired furnace is heated by at least one burner and an amount of the fuel supplied to the at least one burner is measured. 
   
   
       4 . Method according to  claim 3 , wherein an absolute value of said difference between said theoretical concentration of oxygen and said concentration of oxygen detected is calculated based on measured concentrations of oxygen and carbon dioxide and on said measured amount of fuel. 
   
   
       5 . Method according to  claim 4 , further comprising calculating an amount of oxidized metal. 
   
   
       6 . Method according to  claim 1 , wherein said measuring of at least one of said oxygen concentration and said measured carbon dioxide concentration is by means of a laser. 
   
   
       7 . Method according to  claim 1 , wherein said fuel is combusted with the gas containing more than 21% oxygen. 
   
   
       8 . Method according to  claim 3 , wherein said process is controlled by changing power of said at least one burner. 
   
   
       9 . Method according to  claim 1 , further comprising melting a plurality of charges of metal in said furnace, and determining for each charge the difference between said theoretical concentration of oxygen and said measured concentration of oxygen. 
   
   
       10 . Method according to  claim 9 , further comprising comparing the differences between said theoretical concentration of oxygen and said measured concentration of oxygen of at least two charges of the plurality of charges of metal. 
   
   
       11 . Method according to  claim 1 , wherein said metal is contaminated with organic substances, and further comprising partly oxidizing said organic substances with said oxygen and monitoring an amount of oxidized substances.