SYSTEM AND METHOD FOR DIRECT IRON REDUCTION

Abstract

A direct iron reduction (DRI) method is described, comprising generating metallic iron by extracting oxygen from iron ore using a reducing gas mixture with excess carbon monoxide, which produces excess CO2 as a byproduct. The CO2 byproduct is optionally sequestered. A system for carrying out the method is also described.

Description

SYSTEM AND METHOD FOR DIRECT IRON REDUCTION Field of Invention This description refers to methods and systems for the direct reduction of iron ore. In one example, the method includes carbon dioxide sequestration. In another example, the method includes providing for the production of blue ammonia. In yet another example, the method includes providing for the production of blue hydrocarbon fuel. Background of the Invention Direct iron reduction (DRI) is a process that generates metallic iron from its oxide ore by removing oxygen from the iron ore using a reducing gas, usually supplied from synthesis gas. Industrially applied DRI processes include HyL, MIDREX, and FINMET. There continues to be interest in manufacturing processes that reduce or eliminate the release of carbon dioxide (CO2) into the atmosphere, either directly or indirectly. Processes that reduce or eliminate CO2 emissions are generally called "blue" processes, and the products derived from them are also called "blue" products. Summary of the Invention In one example, a reduction method cncnnn / zznz / E / YiAi is provided. Ref. 330566 Direct Iron Reduction (DRI), wherein the method comprises generating metallic iron from its ore by extracting oxygen from the ore by using a supply of reducing gas mixture that produces a carbon dioxide (CO2) byproduct and geologically sequestering the CO2 byproduct. In one aspect, the reducing gas mixture supply comprises hydrogen and carbon monoxide (CO). In another aspect, alone or in combination with either of the above aspects, additional carbon monoxide is added to the reducing gas mixture supply. In another aspect, alone or in combination with any of the above aspects, the CO2 byproduct is separated from the water vapor and the unreacted reducing gas mixture supply before geological sequestration. In another aspect, alone or in combination with any of the above aspects, the CO2 byproduct is dried before geological sequestration. In another aspect, alone or in combination with any of the above aspects, the CO2 byproduct is compressed to a supercritical state before geological sequestration. In another aspect, alone or in combination with any of the above aspects, the unreacted hydrogen from the reducing gas mixture supply is separated from the water vapor and the unreacted reducing gas mixture supply before geological sequestration. In another aspect, alone or in combination with any of the above aspects, the unreacted carbon monoxide is recycled to the reducing gas mixture supply. In another aspect, alone or in combination with any of the above aspects, the unreacted carbon monoxide is recycled to the reducing gas mixture supply such that the hydrogen-to-carbon monoxide (H2 / CO) concentration ratio introduced into a direct reduction unit comprising iron ore is between 3.0 and 0.6. In another aspect, alone or in combination with any of the preceding aspects, the method further comprises directly introducing the metallic iron into an electric arc furnace. In another aspect, alone or in combination with any of the preceding aspects, the introduction of the metallic iron into an electric arc furnace is continuous or semi-continuous. In another example, a direct iron reduction (DRI) system is provided, where the system comprises a direct reduction unit configured to receive a source of iron ore and a supply of reducing gas mixture comprising at least hydrogen and carbon monoxide, a scrubber unit configured to receive a supply of throat gas from the direct reduction unit, and a throat gas separator unit to receive the throat gas supply from the scrubber unit and to provide a supply of carbon dioxide by-product and a supply of unreacted hydrogen and carbon monoxide, a process gas separator unit configured to receive the unreacted hydrogen and / or carbon monoxide from the throat gas separator unit and to provide a supply of carbon monoxide and a supply of essentially pure hydrogen,and a geological carbon dioxide sequestration unit configured to receive the CO2 byproduct supply from the separator unit. In one example, the throat gas separator unit is a CO2 capture unit that selectively provides the CO2 byproduct supply, an unreacted hydrogen supply, and an unreacted carbon monoxide supply. In one aspect, the reducing gas mixture supply comprises hydrogen and carbon monoxide. In another aspect, alone or in combination with either of the above aspects, the carbon monoxide supply from the throat gas supply is recycled to the reducing gas mixture supply. In another aspect, alone or in combination with any of the above aspects, the system further comprises a drying unit configured to receive the CO2 byproduct supply. In another aspect, alone or in combination with any of the above aspects, the system further comprises a compressor configured to receive the CO2 byproduct. In another aspect, alone or in combination with any of the above aspects, the compressor is configured to supply supercritical CO2 to a pipeline for geological sequestration. In another aspect, alone or in combination with any of the above aspects, the geological carbon dioxide sequestration unit is coupled to one or more underground oil fields, natural gas deposits, unexploitable coal deposits, salt formations, shale and basalt formations. In another aspect, alone or in combination with any of the above aspects, the system further comprises a hydrogen storage unit configured to receive the supply of essentially pure hydrogen from the pressure swing absorption unit. In another aspect, alone or in combination with any of the above aspects, the system further comprises an electric arc furnace configured to receive metallic iron. In another aspect, alone or in combination with any of the above aspects, the electric arc furnace is configured to receive metallic iron continuously or semi-continuously. In another aspect, alone or in combination with any of the above aspects, the system is a closed-loop system. In another example, a method for producing ammonia during the direct reduction of iron is provided, wherein the method comprises separating air into an oxygen stream and a nitrogen stream, introducing the oxygen stream into a partial oxidation unit to provide syngas comprising hydrogen and carbon monoxide, generating metallic iron from its ore and a throat gas in a direct reduction unit by using the syngas, separating the throat gas into an essentially pure hydrogen stream, combining the essentially pure hydrogen stream with the nitrogen stream, and producing ammonia. In another aspect, alone or in combination with any of the foregoing aspects, the ammonia is produced continuously or semi-continuously, optionally with the sequestration of carbon dioxide (CO2).In another aspect, either alone or in combination with any of the above aspects, ammonia is produced in a closed-loop system. In another aspect, either alone or in combination with any of the above aspects, ammonia is produced with simultaneous carbon dioxide (CO2) sequestration to provide blue ammonia. In another example, a method for producing a hydrocarbon-based fuel during the direct reduction of iron ore, wherein the method comprises: generating metallic iron from its ore and a throat gas in a direct reduction unit by using a syngas comprising hydrogen and carbon monoxide (CO), separating the throat gas into an essentially pure hydrogen stream and an essentially pure carbon dioxide (CO2) stream, combining the essentially pure hydrogen stream with the essentially pure CO2 stream, and producing hydrocarbon-based fuel. In another aspect, alone or in combination with any of the foregoing aspects, the hydrocarbon-based fuel is produced continuously or semi-continuously, optionally with the sequestration of carbon dioxide (CO2).In another aspect, alone or in combination with any of the above aspects, hydrocarbon-based fuel is produced in a closed-loop system. In another aspect, alone or in combination with any of the above, hydrocarbon fuel is produced with simultaneous carbon dioxide (CO2) sequestration to provide blue hydrocarbon fuel. In another aspect, alone or in combination with any of the above, hydrocarbon-based blue fuel is aviation fuel. In another example, a conditioning system is provided for a direct iron reduction (DRI) unit, where the conditioning system comprises a scrubber unit configured to receive a throat gas supply from a direct reduction unit, a throat gas separator unit to receive the throat gas supply from the scrubber unit and to provide a carbon dioxide by-product supply and a supply of unreacted hydrogen and carbon monoxide, a process gas separator unit configured to receive the unreacted hydrogen and / or carbon monoxide from the throat gas separator unit and to provide a supply of carbon monoxide and a supply of essentially pure hydrogen, and a geological CO2 sequestration unit configured to receive the carbon dioxide by-product supply from the scrubber unit. Brief Description of the Figures In order to understand and see how the present description can be carried out in practice, examples will be described below, only as non-limiting examples, with reference to the attached figures, in which: Fig. 1 is a schematic flow diagram illustrating the main steps for carrying out a DRI process with carbon dioxide sequestration according to one aspect of the present description. Fig. 2 is a schematic illustrating the CO2 sequestration process according to one aspect of the present description. Fig. 3 is a schematic flow diagram illustrating the main steps for carrying out an ammonia synthesis process with DRI according to another aspect of the present description. Fig. 4 is a schematic flow diagram illustrating the main steps for carrying out a hydrocarbon-based fuel synthesis process with DRI according to another aspect of the present description. Detailed Description of the Invention This description outlines a direct reduction (DRI) process capable of producing "blue hydrogen" and subsequently "blue steel." It further describes a method for the direct reduction of iron ore by increasing the amount of carbon monoxide (CO) used in a syngas mixture, followed by the permanent sequestration of the carbon dioxide (CO2) byproduct produced during the iron ore reduction. In one example, the CO2 byproduct is dried and compressed to a supercritical state for permanent sequestration. In another example, the CO2 byproduct is sequestered geologically. In another example, geological sequestration can be combined with one or more terrestrial sequestration or mineral sequestration processes. There are many attempts to produce iron and steel from iron ore using hydrogen. This description also includes the production and storage of "blue hydrogen." Iron / steel production does not use blue hydrogen, but rather the co-acting carbon monoxide from the syngas produced when natural gas or other hydrocarbon feedstocks (e.g., steam reforming, partial oxidation (POX)) are used to generate a hydrogen and carbon monoxide "syngas" stream that provides a source of reducing gas mixture for the DRI (Direct Reduction Iron). Iron ore can be reduced to provide direct iron oxide (DRI) using a reducing agent. For example, the reducing agent can be a reducing gas mixture. A reducing gas mixture can be partially oxidized natural gas. In one example, a partial oxidation process is used in which the feed fuel, such as methane or a suitable hydrocarbon fuel, reacts exothermically in the presence of a small amount of air or oxygen. An example of a reducing gas mixture is partially oxidized natural gas comprising a mixture of hydrogen and carbon monoxide, e.g., "synthetic gas." When mixed with iron ore, the synthetic gas acts as the reducing agent to reduce the iron ore by extracting oxygen from the ore.In one example, syngas with a mixture of hydrogen and carbon monoxide is produced by the partial oxidation of natural gas or other hydrocarbons in a partial oxidation unit (POX) by using nearly pure oxygen in a less than stoichiometric amount relative to the natural gas or hydrocarbons. The reduction of iron oxide in the DRI can be represented by the following general reaction schemes: Fe2O3 + 3H2----> 2Fe + 3H2O Equation (I) Fe2O3+ 3CO ----> 2Fe + 3CO2Equation (II) It is desirable to eliminate CO2 from DRI processes, as CO2 is a gas that contributes to global warming. The present description, in one example, provides a method and system that increases the amount of carbon monoxide in the synthesizer, which would otherwise result in more, rather than less, CO2 being produced during DRI, whereas the method described herein avoids or eliminates the emission of that excess CO2 byproduct into the atmosphere. In one example, the CO2 is dried and / or compressed to a supercritical state. In yet another example, the supercritical CO2 is permanently sequestered. In one example, the permanent sequestration of CO2 involves geological sequestration. As used herein, geological sequestration and its grammatical equivalents include the permanent storage of CO2 in the subsurface and / or underground structures.For example, the subsoil and / or underground structures include, for instance, underground oil deposits, natural gas deposits, unexploitable coal deposits, salt formations, shale, and basalt formations. With reference now to the figures, which represent a direct iron reduction system and method described herein, Fig. 1 shows a scheme where air is introduced into an air separator unit 105, such as a fractional still, air separator unit (ASU), pressure swing adsorption (PSA) unit, or vacuum pressure swing adsorption (VPSA) unit, and oxygen is combined with a hydrocarbon, such as natural gas, in the partial oxidation unit 100 (e.g., a "POX unit") to provide syngas. In one example, high-temperature syngas is supplied in the DRI unit 200 along with iron ore to facilitate the direct reduction of the iron ore and to provide metallic iron, for example, for use in steelmaking. In one example, the syngas exiting the POX 100 unit is at a temperature of approximately 1350 °C and is mixed with carbon monoxide from the unreacted reducing gas mixture supply exiting the DRI 200 unit. The throat gas stream 230 exits the DRI 200 unit and is fed into the scrubber unit 300, which can remove dust and / or airborne particles. After passing through the scrubber unit 300, the throat gas stream 230 is fed into the process gas separator unit 400. In another example, the carbon monoxide from the unreacted reducing gas mixture supply exiting the DRI, after passing through the process gas separator unit 400, is compressed in compressor 450 and then fed into the hot syngas supply.In this example, an excess amount of pressurized carbon monoxide, at a temperature below approximately 1000 °C, is introduced into the hot syngas supply. This cools the hot syngas before it is introduced into the DRI 200 unit and / or the iron ore, thereby reducing sintering and other undesirable effects in the DRI 200 unit. In one example, the syngas with excess carbon monoxide is introduced into the DRI 200 unit at a temperature of approximately 900 °C, approximately 1000 °C, approximately 1100 °C, or approximately 1200 °C. In one example, the syngas supply introduced into the DRI 200 unit is adjusted with essentially pure compressed carbon monoxide from the process gas separator unit 400, so that the hydrogen-to-carbon monoxide (H2 / CO) ratio is between 3.0 and 0.6. In one example, the hydrogen-to-carbon monoxide (H2 / CO) ratio is less than 3, less than 2, less than 1.5, less than 1.0 or less than 0.7, but greater than 0.6. In one example, process gas separator unit 400 independently provides a source of carbon monoxide, e.g., carbon monoxide with a purity of approximately 40% to approximately 98%, with remaining amounts of one or more of nitrogen (N2), water vapor (H2O), hydrogen (H2), methane (CH4), and carbon dioxide (CO2). Process gas separator unit 400 may include a cryogenic separator, a pressure swing adsorption (PSA) unit, or a vacuum pressure swing adsorption (VPSA) unit, and the like. In one example, the pure carbon monoxide from the unreacted reducing gas mixture supply exiting process gas separator unit 400 provides for carbon monoxide recycling.In one example, excess carbon monoxide from the unreacted reducing gas mixture supply leaving the DRI unit is scrubbed in scrubbing unit 300, separated from carbon dioxide in throat gas separator unit 350, separated from hydrogen in process gas separator unit 400, and compressed in compressor 450 before being introduced / recycled into the reducing gas mixture supply (e.g., syngas). In one example, reduced iron 225 from DRI unit 200 is deposited in an electric arc furnace (EAF) 700. In another example, reduced iron 225 is deposited directly into electric arc furnace 700. In another example, reduced iron 25 is deposited continuously or semi-continuously in electric arc furnace 700. The unreacted syngas, along with water vapor and the CO2 byproduct, exits the DRI unit's throat as throat gas stream 230. In one example, water 325 is condensed from throat gas stream 230 by scrubbing unit 300, and the CO2 byproduct cncnnn / zznz / E / YiAi is separated in throat gas separator unit 350, yielding a purified CO2 byproduct stream. Throat gas separator unit 350 may include a cryogenic separator, a pressure swing adsorption (PSA) unit, or a vacuum pressure swing adsorption (VPSA) unit, and the like. The purified CO2 byproduct stream is then dried and compressed in compressor unit 500 and fed into the CO2 geological sequestration unit 600. The remaining gas coming out of the 350 throat gas separator unit is rich in hydrogen and also contains amounts of carbon monoxide.Therefore, the hydrogen and carbon monoxide exiting the 350 throat gas separator unit are then separated in the 400 process gas separator unit. The 400 process gas separator unit provides a source of "blue hydrogen," which is essentially pure blue hydrogen—for example, at least 96%, at least 97%, or at least 98% pure hydrogen. This essentially pure blue hydrogen can be stored, such as in tank 750. With reference to Fig. 2, the DRI 200 unit is coupled via piping 650 to the CO2600 geological sequestration unit. In one example, an existing DRI 200 unit comprising a partial oxidation unit or a steam reformer is retrofitted with a scrubber unit configured to receive a throat gas supply, a throat gas separator unit to receive the throat gas supply from the scrubber unit and to provide a carbon dioxide by-product supply and a supply of unreacted hydrogen and carbon monoxide, and a process gas separator unit configured to receive the unreacted hydrogen and / or carbon monoxide from the throat gas separator unit and to provide a supply of essentially pure carbon monoxide and a supply of essentially pure hydrogen. In one example, one or more additional components are employed, e.g., for heat recovery and / or heating in air conditioning. The CO2 byproduct is geologically sequestered in one or more subsurfaces and / or underground structures. In one example, the one or more subsurfaces and / or underground structures are deeper than the colluvium or alluvium layers 800 or the groundwater 805. In one example, the CO2 byproduct is geologically sequestered in the subsurface and / or underground structures, which include, for example, underground oil reservoirs 810 interbedded between confining layers 807, natural gas deposits 815, unexploitable coal deposits 820, salt formations 825, shale and / or basalt formations (not shown). With reference to Fig. 3, an alternative embodiment of the present description is provided, wherein the method and the cncnnn / zznz / E / YiAi system, alone or in combination with CO2 sequestration, are used to provide a source of "blue" ammonia. Therefore, essentially pure nitrogen from air separation unit 105, together with a stream of essentially pure blue hydrogen from process gas separator unit 400, is sent to converter 900 to produce "blue" ammonia. Converter 800 accommodates the conventional Haber or Haber-Bosch process, the Nernst process (with iron catalyst), the Kellogg process, or solid-state heterogeneous catalytic process equipment, or similar. In Fig. 3, CO2 sequestration and / or hydrogen storage are optional. With reference to Fig. 4, an alternative embodiment of the present description is provided, where the method and system, alone or in combination with CO2 sequestration, are used to provide a source of "blue" fuel, such as aviation fuel. Therefore, the essentially pure, cleaned, and dried CO2 from the scrubber unit 300 / throat gas separator unit 350 and / or the dry CO2 from the compressor / dryer unit 500, together with the essentially pure blue hydrogen stream from the process gas separator unit 400, is sent to the catalytic converter 950 to produce hydrocarbon-based "blue" fuel, such as aviation fuel. The catalytic converter 900 may include indirect processing (using methanol) or direct processing (reverse water-gas displacement reactions), Fisher-Tropsch synthesis (hydrogenation), iron, manganese, and potassium catalysts, or similar. In Fig.4, CO2 sequestration and / or hydrogen storage is optional. Therefore, the present description provides, in one example, a closed-loop system where essentially pure CO2 is sequestered, and essentially pure hydrogen is obtained for sale with essentially zero carbon emissions. The present description also provides for the production of "blue iron" which, when coupled to an electric arc furnace or similar process, ultimately yields "blue steel." Whereas traditional iron ore processing to produce metallic iron produces up to 1,000 kilograms (1 tonne) of CO2 emissions per 1,000 kilograms (1 tonne) of iron, the present description provides for a process that produces essentially zero tonnes of CO2 emissions per 1,000 kilograms (1 tonne) of iron. While certain modalities of this description have been illustrated with reference to specific combinations of elements, other diverse combinations may also be provided without departing from the indications of this description. Therefore, this description should not be interpreted as limited to the particular example modalities described herein and illustrated in the Figures, but may also encompass combinations of elements from the various illustrated modalities and aspects thereof. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A direct iron reduction (DRI) method, characterized in that it comprises: generating metallic iron from its ore by extracting oxygen from the ore using a supply of reducing gas mixture that produces a CCg byproduct; and geologically sequestering the CO2 byproduct.

2. The method according to claim 1, characterized in that the supply of reducing gas mixture comprises hydrogen and carbon monoxide.

3. The method in accordance with any of the preceding claims, characterized in that additional carbon monoxide is added to the supply of reducing gas mixture.

4. The method according to any of the preceding claims, characterized in that the CO2 by-product is separated from the water vapor and the unreacted reducing gas mixture supply prior to geological sequestration.

5. The method in accordance with any of the preceding claims, characterized in that the cncnnn / zznz / E / YiAi by-product of CC>2 is dried before geological sequestration.

6. The method in accordance with any of the preceding claims, characterized in that the CO2 by-product is compressed to a supercritical state prior to geological sequestration.

7. The method according to any of the preceding claims, characterized in that the unreacted hydrogen from the reducing gas mixture supply is separated from the water vapor and the unreacted reducing gas mixture supply prior to geological sequestration.

8. The method according to any of the preceding claims, characterized in that the unreacted carbon monoxide is recycled to the supply of reducing gas mixture so that a hydrogen to carbon monoxide (H2 / CO) concentration ratio introduced into a direct reduction unit comprising iron ore is between 3 and 0.

6.

9. The method in accordance with any of the preceding claims, characterized in that it further comprises introducing the metallic iron into an electric arc furnace.

10. The method according to claim 9, characterized in that the introduction of metallic iron into an electric arc furnace is continuous or semi-continuous.

11. A direct iron reduction (DRI) system, characterized in that it comprises: a direct reduction unit configured to receive an iron ore source and a supply of reducing gas mixture comprising at least hydrogen and / or carbon monoxide; a scrubber unit configured to receive a throat gas supply from the direct reduction unit; a throat gas separator unit to receive the throat gas supply from the scrubber unit and to provide a carbon dioxide by-product supply and a supply of unreacted hydrogen and carbon monoxide; a process gas separator unit configured to receive the unreacted hydrogen and / or unreacted carbon monoxide from the throat gas separator unit and to provide a supply of carbon monoxide and a supply of essentially pure hydrogen;and a geological CO2 sequestration unit configured to receive the carbon dioxide byproduct supply from the scrubbing unit.

12. The direct iron reduction system according to claim 11, characterized in that the supply of reducing gas mixture comprises hydrogen and carbon monoxide.

13. The direct iron reduction system according to any of claims 12 or 11, characterized in that the carbon monoxide supply from the process gas separator is recycled to the reducing gas mixture supply so that the hydrogen concentration ratio to carbon monoxide (H2 / CO) introduced into the direct reduction unit is between 3 and 0.

6.

14. The direct iron reduction system according to any of claims 11-13, characterized in that it further comprises a drying unit configured to receive the CO2 by-product supply and / or further comprises a compressor configured to receive the CO2 by-product.

15. The direct iron reduction system according to claim 14, characterized in that the compressor is configured to supply supercritical CO2 to a pipe for geological sequestration.

16. The direct iron reduction system according to any of claims 11-15, characterized in that the geological CO2 sequestration unit is coupled to one or more underground oil fields, natural gas deposits, non-exploitable coal deposits, salt formations, shale and basalt formations.

17. The direct iron reduction system according to claim 11, characterized in that it further comprises a hydrogen storage unit configured to receive the supply of essentially pure hydrogen from a pressure swing absorption unit or a cryogenic unit.

18. The direct iron reduction system according to claim 11, characterized in that it further comprises an electric arc furnace configured to receive metallic iron.

19. The direct iron reduction system according to claim 18, characterized in that the electric arc furnace is configured to receive metallic iron continuously or semi-continuously.

20. The direct iron reduction system according to any of claims 18 or 19, characterized in that the system is a closed circuit system.

21. A method for producing ammonia during the direct reduction of iron ore, characterized in that it comprises: separating air into an oxygen stream and a nitrogen stream; introducing the oxygen stream into a partial oxidation unit to provide syngas comprising hydrogen and carbon monoxide; generating metallic iron from its ore and a throat gas in a direct reduction unit by using the syngas; separating the throat gas into an essentially pure hydrogen stream; combining the essentially pure hydrogen stream with the nitrogen stream; and producing ammonia.

22. The method according to claim 21, characterized in that the ammonia is produced with simultaneous CO2 sequestration so as to provide blue ammonia.

23. A method for producing a hydrocarbon-based fuel during the direct reduction of iron ore, characterized in that it comprises: generating metallic iron from its ore and a throat gas in a direct reduction unit by using a syngas comprising hydrogen and carbon monoxide (CO); separating the throat gas into an essentially pure hydrogen stream and an essentially pure carbon dioxide (CO2) stream; combining the essentially pure hydrogen stream with the essentially pure CO2 stream; and producing hydrocarbon-based fuel.

24. The method according to claim 23, characterized in that the hydrocarbon fuel is produced with simultaneous CO2 sequestration so as to provide cncnnn / zznz / E / YiAi blue hydrocarbon fuel.

25. The method according to claim 24, characterized in that the hydrocarbon-based blue fuel is aviation fuel.

26. A conditioning system for a direct iron reduction (DRI) unit, characterized in that it comprises: a scrubber unit configured to receive a throat gas supply from a direct reduction unit, a throat gas separator unit to receive the throat gas supply from the scrubber unit and to provide a CO2 by-product supply and a supply of unreacted hydrogen and carbon monoxide, a process gas separator unit configured to receive the unreacted hydrogen and / or carbon monoxide from the throat gas separator unit and to provide a supply of carbon monoxide and a supply of essentially pure hydrogen; and a CCt geological sequestration unit configured to receive the CO2 by-product supply from the scrubber unit.