Preheating oxygen for injection into blast furnaces

Abstract

A side stream of hot blast air is used to preheat oxygen at a heat exchanger. The resultant hot oxygen is injected into a tuyere of a blast furnace with pulverized or granular coal. The cooled side stream may be recombined with the hot blast air for injection into the tuyere, fed to the stove as part of the cold blast air, or fed to stove for combustion with blast furnace gas.

What is claimed is: 
     
         1 . A method for heating oxygen for injection into a tuyere of a blast furnace, comprising the steps of:
 feeding cold blast air to a first stove to produce a stream of hot blast air;   dividing the stream of hot blast air from the blast air stove into a hot side stream of hot blast air and a remaining stream of hot blast air;   heating a stream of industrially pure oxygen at a heat exchanger through heat exchange with the hot side stream to yield a heated oxygen stream and a cooled side stream; and   injecting pulverized or granular coal and the heated oxygen stream into the tuyere for combustion of the injected coal and oxygen.   
     
     
         2 . The method of  claim 1 , further comprising the step of diluting the hot side stream with ambient air upstream of the heat exchanger. 
     
     
         3 . The method of  claim 1 , further comprising the step of combining the cooled side stream with the remaining stream. 
     
     
         4 . The method of  claim 1 , further comprising the step of feeding the cooled side stream to a second stove as part of combustion air fed to the second stove. 
     
     
         5 . The method of  claim 1 , further comprising the step of feeding the cooled side stream to the first stove as part of cold blast air that is heated at the first stove. 
     
     
         6 . A blast furnace installation utilizing hot oxygen tuyere injection, comprising:
 a first stove receiving cold blast air and producing a stream of hot blast air;   a heat exchanger adapted and configured to heat ambient oxygen through heat exchange with a portion of the stream of hot blast air; and   a blast furnace including a tuyere that is adapted and configured to receive hot blast air, pulverized or granular coal, and also hot oxygen from the heat exchanger.   
     
     
         7 . The installation of  claim 6 , wherein the tuyere is adapted and configured to also receive the portion of hot blast air that is cooled at the heat exchanger. 
     
     
         8 . The installation of  claim 6 , wherein, at a point upstream of the tuyere, a line conveying the hot blast air to the tuyere receives the portion of hot blast air that is cooled at the heat exchanger. 
     
     
         9 . The installation of  claim 6 , further comprising a second stove that receives the portion of the stream of hot blast air that is cooled at the heat exchanger and that is adapted and configured to combust such cooled portion with blast furnace gas. 
     
     
         10 . The installation of  claim 6 , wherein the first stove receives the portion of the stream of hot blast air that is cooled at the heat exchanger as part of the cold blast air.