Method for heating a blast furnace stove

Abstract

A method for heating a blast furnace stove includes combining flue gas recycling and oxy-fuel combustion for concentrating CO 2 for facilitating carbon capture and reducing CO 2 emissions from a plant operatively associated with the stove. Top gas from a blast furnace associated with the stove may be the fuel for the stove.

What is claimed is: 
     
         1 . A method for heating a blast furnace stove ( 300 ,  400 ,  500 ,  600 ) comprising: combining flue gas recycling and oxy-fuel combustion for concentrating CO 2  for facilitating carbon capture and reducing CO 2  emissions from a plant operatively associated with the stove. 
     
     
         2 . The method of  claim 1 , wherein the oxy-fuel combustion, comprises combusting a fuel with a lower heating value (LHV) of not more than 9 MJ/Nm 3  in a combustion zone of said stove, said zone arranged in a combustion chamber ( 301 ; 401 ; 501 ; 601 ) in the stove, flowing combustion gases through and heating refractory material ( 302 , 402 , 502 , 602 ) in the stove, combusting the fuel with an oxidant comprising at least 85% oxygen, recirculating the combustion gases into the combustion zone, and diluting the mixture of fuel and oxidant in said zone sufficiently for the combusting to be flameless. 
     
     
         3 . The method of  claim 2 , further comprising recirculating the combustion gases from a location within the combustion chamber ( 301 ; 401 ) but outside the combustion zone, supplying the oxidant to the combustion zone at high velocity through at least one lance ( 310 , 311 , 312 ), and entraining the combustion gases into the combustion zone for diluting the flame. 
     
     
         4 . The method of  claim 3 , wherein the supplying the oxidant comprises lancing the oxidant at a velocity of at least 200 m/s. 
     
     
         5 . The method of  claim 4 , wherein the lancing is at least at sonic velocity. 
     
     
         6 . The method of  claim 5 , further comprising arranging an orifice ( 416 ) of the at least one lance adjacent a supply inlet for fuel ( 413 ), and entraining said fuel into the combustion zone by ejector action. 
     
     
         7 . The method of  claim 6 , further comprising providing additional oxidant to the combustion chamber ( 301 ) downstream of the supply inlet for the fuel ( 413 ) for achieving staged combustion in the combustion zone. 
     
     
         8 . The method of  claim 2 , further comprising supplementing an existing air burner for the stove with at least one high-velocity oxidant lance for injecting said oxidant. 
     
     
         9 . The method of  claim 2 , further comprising recycling combustion gases flowing through the refractory material ( 502 , 602 ) back into the combustion zone. 
     
     
         10 . The method of  claim 9 , further comprising premixing the recycled combustion gases with said oxidant before entering the combustion zone. 
     
     
         11 . The method of  claim 9 , wherein the recycling of the combustion gases is complete when total oxygen percentage by volume of an inert part of the combustion chamber ( 501 , 601 ), excluding non-inert fuel components, does not exceed 12%. 
     
     
         12 . The method of  claim 9  further comprising replacing an existing air burner in the stove ( 500 ) with a fuel inlet ( 516 ) and a recycled combustion gases inlet ( 513 ), and combusting the fuel with said oxidant. 
     
     
         13 . The method of  claim 12 , wherein a sufficient amount of the combustion gases are recycled to maintain the gas mass flow per time unit through the refractory material ( 502 , 602 ) at a level which is at least the same as the gas mass flow per time unit which was used when the existing air burner was operated without recycling. 
     
     
         14 . The method of  claim 12 , wherein a sufficient amount of the combustion gases are recycled to maintain a flame temperature at a level which is not more than, and a thermal energy transfer to the refractory material ( 502 , 602 ) at a level which is not less than, the flame temperature and the thermal energy throughput per time unit, respectively, which was used when the existing air burner was operated without recycling. 
     
     
         15 . The method of  claim 2 , wherein the fuel comprises blast furnace top gas. 
     
     
         16 . The method of  claim 15 , further comprising obtaining the blast furnace top gas from a blast furnace supplied with hot air from the stove ( 300 , 400 , 500 , 600 ). 
     
     
         17 . The method of  claim 1 , wherein the concentrating CO 2  from flue gases is at 50-60% of said flue gas. 
     
     
         18 . The method of  claim 1 , further comprising separating CO 2  contents from combustion gases to be vented from the stove for carbon capture before said combustion gases are released to the environment. 
     
     
         19 . The method of  claim 1 , wherein the facilitating carbon capture is with combustion gases from said blast furnace stove. 
     
     
         20 . The method of  claim 10 , further comprising calculating a total amount of oxygen used per time unit for determining an amount of the recycled combustion gases for the premixing before the entering the combustion zone.