Blast furnace iron production with integrated power generation

Abstract

An integrated system for blast furnace iron making and power production based upon higher levels of oxygen enrichment in the blast gas is disclosed. The integrated system leads to; 1) enhanced productivity in the blast furnace, 2) more efficient power production, and 3) the potential to more economically capture and sequester carbon dioxide. Oxygen enhances the ability of coal to function as a source of iron reductant and to be gasified within the blast furnace thereby generating an improved fuel-containing top gas.

1 . A method for producing iron comprising:
 introducing iron ore, coke and coal into a blast furnace, whereby the coal is gasified in the presence of steam and super-enriched air that are introduced into a blast furnace,   recovering from the blast furnace a top gas and using the top gas to generate power; and,   recovering hot metal from the blast furnace; wherein the super enriched air is introduced into the blast furnace at a temperature of less than about 1250 C and hot metal is produced at a reducing agent to iron ratio of greater than or equal to about 0.40 kg of carbon per kg of iron produced.   
     
     
         2 . The method of  claim 1  wherein the air is enriched with oxygen from at least one member selected from the group consisting of an air separation unit, ion transport membrane and a VPSA. 
     
     
         3 . The method of  claim 1  further comprising removing carbon dioxide from the top gas prior to said using. 
     
     
         4 . The method of  claim 1  wherein the air blast is super-enriched with oxygen to a level above about 36% oxygen. 
     
     
         5 . The method of  claim 1  wherein the usage of coke is less than about 300 kg per metric ton of hot metal and the coal rate is at least about 200 kg of coal per metric ton of hot metal. 
     
     
         6 . The method of  claim 2  wherein the air separation unit comprises a cryogenic distillation air separation unit. 
     
     
         7 . A method for generating power comprising:
 providing at least a portion of top gas from an iron producing blast furnace wherein the top gas comprises carbon monoxide, carbon dioxide, hydrogen, and nitrogen each in concentrations such that the top gas has a calorific value, without supplemental fuel, that is sufficient to operate a gas turbine,   compressing and supplying this top gas to the gas turbine, and;   introducing an exhaust from the gas turbine into a heat recovery steam generator under conditions sufficient to operate a steam turbine.   
     
     
         8 . The method of  claim 7  wherein the compressed gas supplied to the gas turbine is combined with nitrogen. 
     
     
         9 . The method of  claim 8  wherein: i) the nitrogen is generated by an air separation unit (ASU) that supplies oxygen into the blast furnace, and/or ii) oxygen obtained from said ASU is used to combust a portion of the blast furnace top gas at a HRSG and/or iii) nitrogen from the ASU is supplied to the gas turbine. 
     
     
         10 . The method of  claim 7  further comprising removing carbon dioxide from the top gas prior to introducing the gas into a gas turbine. 
     
     
         11 . The method of  claim 10  further comprising converting at least a portion of the carbon monoxide into carbon dioxide prior to said removing carbon dioxide. 
     
     
         12 . A method for producing iron and gasifying coal comprising:
 introducing iron bearing materials, and coke into a blast furnace, introducing coal into the iron blast furnace, and;   introducing air enriched in oxygen into the blast furnace,   wherein the conditions within the blast furnace are sufficient to produce iron and convert at least a portion of the coal into a gas comprising carbon monoxide, carbon dioxide and hydrogen;   removing a portion of the gas from the furnace;   removing at least a portion of the carbon dioxide from the gas and supplying the gas to at least one of: i) a combined cycle power generation system and supplying steam generated by the combined cycle power generation system to the blast furnace, and ii) a water shift reactor to produce hydrogen; and,   recovering iron from the iron blast furnace.   
     
     
         13 . The method of  claim 12  wherein the oxygen used to enrich the air is supplied from an air separation unit. 
     
     
         14 . The method of  claim 12  wherein the gas is supplied to a shift reactor wherein carbon monoxide and water are converted into carbon dioxide and hydrogen. 
     
     
         15 . The method of  claim 13  wherein nitrogen generated by the air separation unit is supplied to at least one of the CO2 removing step, and supplying the gas to a combined cycle power generation system. 
     
     
         16 . The method of  claim 13  where the furnace is supplied with a mixture comprising oxygen, steam and at least one of CO, CO2 and H2, and the gas is substantially free of nitrogen. 
     
     
         17 . The method of  claim 7  wherein an exhaust exiting the steam turbine is substantially free of CO2. 
     
     
         18 . The method of  claim 7  wherein at least a portion of the topgas is combusted in the presence of oxygen from an ASU in a burner of the heat recovery steam generator. 
     
     
         19 . An integrated system for producing iron and producing power comprising:
 an iron blast furnace and a top gas system for receiving the top gas from the iron blast furnace,   a coal delivery system that supplies coal to the iron blast furnace,   a carbon dioxide removal system that removes carbon dioxide from gas received from the top gas system,   a combined cycle power generation system,   a steam delivery system for supplying steam from the combined cycle power generation system to the iron blast furnace; and,   an air separation unit and a delivering system for supplying oxygen from the unit to the blast furnace and nitrogen from the unit to the combined cycle power generation system.   
     
     
         20 . The system of  claim 19  further comprising a water shift reactor that receives top gas from the top gas system and generates hydrogen. 
     
     
         21 . The method of  claim 1  wherein the temperature is less than about 850 C. 
     
     
         22 . The method of  claim 1  wherein the ratio is greater than or about 0.45 kg.