Apparatus for controlling introduced air in metal oxide reducing furnace

Abstract

An introduced-air-flow-rate SA is determined by adding an adjusted value A given from an oxygen density controlling system to a required-air-reference-flow-rate RA demanded by the charging amount of pellets The introduced-air-flow-rate is controlled where the required-air-reference-flow-rate RA is the feed forward value Thus, it the charging amount of the pellet is varied, since the introduced-air-flow-rate SA is determined by the adjusted value A and the required-air-reference-flow-rate RA varied in response thereto, the control response can be quickened without decrease of the stability. Further, at the abnormality of the oxygen sensor, as the adjusted value A is controlled to be zero, the required-air-reference-flow-rate RA is decided of itself as the introduced-air-flow-rate SA

What is claimed is:  
     
         1 . An apparatus for controlling an introduced air in a metal oxide reducing furnace, 
 wherein said metal oxide reducing furnace heats processed materials containing metal oxides and reducing materials under a reducing atmosphere while transferring from a starting position said processed materials in one direction within a furnace chamber, to thereby reduce metal oxides for obtaining a metal from said processed materials,    wherein said metal oxide reducing furnace introduces air into a predetermined position of the furnace chamber so as to cause a complete combustion of an inflammable gas staying in the furnace chamber, and then said metal oxide reducing furnace discharges the thus completely combusted gas from a gas discharging position in adjacent to the starting position,    wherein said metal oxide reducing furnace measures an oxygen density within the furnace chamber by use of an oxygen densitometer that is disposed in the vicinity of the gas discharging position, and    wherein said metal oxide reducing furnace controls an introduced-air-flow-rate of air introduced into the predetermined position by use of an adjusted value that is calculated in accordance with deviation between the measured value of the oxygen density and an reference oxygen density,    said controlling apparatus comprising: 
 means for determining, in accordance with the amount of the processed materials that is charged into the furnace, a processed-materials-requesting-air-flow-rate that is requested to take a complete combustion of gas which is generated from the processed materials,  
 abnormality judging means for judging abnormality of the oxygen densitometer,  
 means for controlling the adjusted value to be at zero when the abnormality of the oxygen densitometer is judged by the abnormality judging means, and  
 means for determining the introduced-air-flow-rate by adding processed-materials-requesting-air-flow-rate and the adjusted value.  
   
     
     
         2 . The introduced air controlling apparatus according to  claim 1 , further comprising: 
 means for determining, in accordance with flow rates of air and fuel gas that are supplied into the furnace chamber for heating the processed materials, a shortage-air-flow-rate insufficient with respect to the complete combustion of the fuel gas,    wherein said means of determining the introduced-air-flow-rate determines the introduced-air-flow-rate by adding the processed-materials-requesting-air-flow-rate, the shortage-air-flow-rate and the adjusted value.    
     
     
         3 . The introduced air controlling apparatus according to  claim 1 , wherein said processed-materials-requesting-air-flow-rate determining means determines, as the processed-materials-requesting-air-flow-rate, a value larger by a predetermined value than a value that is determined in correspondence to the amount of the processed materials that have been actually charged.  
     
     
         4 . The introduced air controlling apparatus according to  claim 2 , wherein said processed-materials-requesting-air-flow-rate determining means determines, as the processed-materials-requesting-air-flow-rate, a value larger by a predetermined value than a value that is determined in correspondence to the amount of the processed materials that have been actually charged.  
     
     
         5 . The introduced air controlling apparatus according to  claim 1 , wherein the furnace chamber is formed into a doughnut shape, and the processed materials is laid on a doughnut shaped hearth and then rotated around the axis thereof so as to be transferred in a circumferential direction of the furnace chamber.  
     
     
         6 . An apparatus for controlling an introduced air in a metal oxide reducing furnace, wherein said metal oxide reducing furnace comprises, a furnace chamber into which the processed materials containing metal oxides and reducing materials are charged, a hearth disposed within said furnace chamber for transferring the processed materials within said furnace chamber, a heater disposed at said furnace for heating the processed materials, an air introducing member disposed at said furnace, a fuel gas introducing member disposed at said furnace, and an oxygen densitometer measuring an oxygen density within the furnace chamber, 
 said controlling apparatus comprising: 
 means for determining, in accordance with the amount of the processed materials that are charged into the furnace chamber, a processed-materials-requesting-air-flow-rate that is requested to take a complete combustion of gas which is generated from the processed materials;  
 means for determining, an introduced-air-flow-rate of an air introduced by the air introducing member, by adding the processed-materials-requesting-air-flow-rate and an adjusted value that is calculated in accordance with deviation between the measured value of the oxygen density and an reference oxygen density;  
   abnormality judging means for judging abnormality of the oxygen densitometer; and    means for controlling the adjusted value to be at zero when the abnormality of the oxygen densitometer is judged by the abnormality judging means.    
     
     
         7 . The controlling apparatus according to  claim 6 , further comprising: 
 means for determining, in accordance with flow rates of the air and the fuel gas that are introduced into the furnace chamber, a shortage-air-flow-rate insufficient to take a complete combustion of the fuel gas,    wherein said introduced-air-flow-rate determining means determines the introduced-air-flow-rate by adding the processed-materials-requesting-air-flow-rate, the shortage-air-flow-rate and the adjusted value.    
     
     
         8 . The introduced air controlling apparatus according to  claim 6 , wherein said processed-materials-requesting-air-flow-rate determining means determines, as the processed-materials-requesting-air-flow-rate, a value larger by a predetermined value than a value that is determined in correspondence to the amount of the processed materials that have been actually charged.  
     
     
         9 . The introduced air controlling apparatus according to  claim 7 , wherein said processed-materials-requesting-air-flow-rate determining means determines, as the processed-materials-requesting-air-flow-rate, a value larger by a predetermined value than a value that is determined in correspondence to the amount of the processed materials that have been actually charged.