Smart hydrogen production for DRI production

Abstract

The present invention relates to the production of direct reduced iron, DRI, where hydrogen direct reduction is carried out synergistically in accordance with the realities of an industrial plant. The hydrogen reduction is carried out with a reducing gas containing at least 85% by volume of hydrogen, receiving a make-up hydrogen stream, at least a part of which is produced on-site by at least one of (i) electrolysis means configured to produce hydrogen from steam recovered from one or more components of the industrial plant and / or from steam generated using waste heat and / or hot gases emitted by one or more components, (ii) gas shift reaction means configured to convert CO2-containing gases emitted by at least one component of the industrial plant into hydrogen and remove CO2.

Description

Background of the Invention

[0001] The need and obligation to reduce global CO2 emissions is affecting the steel industry as one of the key responsible players. Global decarbonization is pushing steel manufacturers to transition to more sustainable production based on the H2DRI process. Hydrogen is a key new element for current CO2 reduction and especially for future decarbonized steel production (green hydrogen).

[0002] Currently, the main integrated hydrogen production processes are: i) Steam reforming of natural gas This process is the most common and cheapest industrial source of hydrogen. Natural gas is heated to 700-1100°C in the presence of steam and a nickel catalyst. Methane molecules are split to form carbon monoxide and hydrogen. The carbon monoxide gas is passed with steam over iron oxide or other oxides and undergoes a water gas shift reaction to produce additional hydrogen. Hydrogen produced in this way is economically attractive, but requires fossil fuels and the capture of CO2 to avoid emissions.

[0003] ii) Electrolysis (electrolysis) unit Water-based electrolysis units consist of several cells, each consisting of one anode and one cathode, submerged in an electrolyte and connected to a power source. Electricity splits the water inlet flow into hydrogen and oxygen. Steam-fed electrolysis units produce hydrogen and oxygen based on much the same principles as their aqueous counterparts, using steam instead as input. Water-fed electrolysis units are expensive in terms of capital expenditures (CapEx) and operational costs (OpEx). Steam-fed electrolysis units are expensive in terms of capital expenditures (CapEx) and operational costs (OpEx); however, due to their higher efficiency, they have lower operational costs than water-fed electrolysis units. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, as hydrogen production currently involves high costs, the main driver is to find new sustainable alternative solutions for using hydrogen while reducing the associated costs. [Means for solving the problem]

[0005] The present invention aims to find attractive configurations for producing hydrogen in an industrial environment in a sustainable and competitive manner.

[0006] The present invention discloses a plant and method for producing DRI in a hydrogen direct reduction (DR) plant.

[0007] The production of hydrogen (H2) for the hydrogen DR plant is achieved through an innovative setup that uses a gas shift reaction plant and / or a feed steam electrolysis unit to produce hydrogen using energy carriers already present in the complex steel plant (or more generally at the industrial site).

[0008] The energy carrier mentioned above is steam and / or a CO-containing gas. According to the present invention, a method for producing direct reduced iron, DRI, comprises: the shaft furnace is connected to a process gas loop arranged to receive top gas from the shaft furnace, treat the top gas before heating it in the heater device, and a hydrogen stream (commonly referred to as make-up hydrogen) is added to the process gas loop upstream of the heater device to return a reducing gas containing at least 85% by volume of hydrogen to the furnace, so that the iron ore is reduced in the hydrogen reducing atmosphere in the shaft furnace; Direct Reduction (DR) operating the plant; operating an industrial plant to produce a CO2-containing gas and / or steam and / or waste heat and / or hot gas; At least a portion of the hydrogen stream (make-up hydrogen stream) Electrolysis means configured to produce hydrogen from steam recovered from one or more components of the industrial plant and / or from steam generated using waste heat and / or hot gases emitted by one or more components; and and / or a gas shift reactor means configured to convert CO2-containing gas released by at least one component of the industrial plant into a hydrogen-rich gas, and preferably to remove CO2.

[0009] A "hydrogen DR plant" can be a DR plant in which hydrogen is supplied as reducing gas. The hydrogen content of the reducing gas is between 85 and 100% by volume, preferably 85 or more than 90% by volume, e.g., between 90 and 95% by volume. Such a hydrogen DR plant typically includes a shaft furnace and an associated recycle gas loop, known as a process gas loop, through which furnace top gas is treated (typically cleaned and compressed), heated, and recycled to the furnace as reducing gas with the above-mentioned hydrogen content. An optional fuel gas loop (using a portion of the recycled top gas) can be used for heating purposes in a heater unit. Hydrogen provided by a hydrogen stream, commonly referred to as a make-up hydrogen stream, is added to the process gas loop in an amount sufficient to reach the above-mentioned hydrogen concentration range according to process requirements. The role of the make-up hydrogen stream is therefore to supplement the amount of hydrogen in the process loop until the desired H2 operating concentration in the reducing gas is reached. The hydrogen make-up stream can typically have an H2 content of 90 to 100% by volume. A hydrogen DR plant can typically be a MIDREX® H2 plant.

[0010] Steam may be recovered from any component of an industrial site where steam is available. Alternatively or additionally, steam may be produced by any known heat recovery facility using waste heat sources present in industrial processes that would otherwise result in heat loss. Heat recovery facilities may typically include a heat exchanger configured to bring hot gases / waste heat and water into heat exchange relationship to produce steam. The heat recovery device may include, for example, a boiler in which water is heated by the hot gases / waste heat.

[0011] The steam so produced is fed to one or more feed steam electrolysis units capable of converting the steam to hydrogen and oxygen using electricity as input. Any suitable electrolysis unit capable of separating oxygen from water steam can be used, for example, a solid oxide electrolysis cell (SOEC).

[0012] The CO-containing gas can be any available industrial gas with a significant carbon monoxide content (e.g., at least 20% by volume, 20-25% by volume in some embodiments, although other gases with higher CO concentrations can be used). The CO-containing gas can be any metallurgical gas present throughout the plant with a low carbon monoxide content (e.g., BF gas, BOF gas, TGF gas, SAF off-gas, etc.), preferably a low nitrogen content, depending on the steelmaking situation. A water-gas shift (WGS) system with CO removal converts the CO-containing gas into a carbon dioxide (CO) stream, which is separated from other gases and becomes a substantially hydrogen-rich stream. Various technologies can be used, such as those used in the art for pre-combustion CO capture. Hereinafter, this system will be referred to as a gas shift reaction plant (GSRP). As known in the art, a GSRP can include a WGS reactor combined with a CO capture system (e.g., amine technology). Alternatively, integrated technologies can be used whereby a single reactor is configured to perform the WGS reaction and separate CO. These technologies are known in the art and need not be further detailed.

[0013] Any conventional steam feed electrolysis unit, any GSRP plant and any heat recovery device adapted to produce steam may be used in accordance with the present invention.

[0014] In an embodiment, the hydrogen DR plant is combined with a natural gas DR plant located at an industrial site. The natural gas DR plant may typically be a MIDREX NG plant, or may be replaced by a MIDREX MxCol plant or a NG / H2 plant.

[0015] A natural gas DR plant traditionally operates on reformed natural gas to produce DRI from iron ore. It includes an additional shaft furnace and an additional process gas loop containing a heater / reformer to produce synthesis gas from natural gas (and recycled process gas). This synthesis gas is used as reducing gas in different shaft furnaces, and the typical composition of the reducing gas fed to the furnace is about 30-34 vol% CO, 0-4% CO2, 50-55% H2, 2-6% H2O, 1-4% CH4, and 0-2% N2.

[0016] As will be appreciated by those skilled in the art, natural gas DR plants emit a top gas that is hot and contains CO. Conventional natural gas DR plants can operate synergistically with hydrogen DR plants to reduce the need for hydrogen from external sources. The same can be done for MxCol and NG / H2 plants.

[0017] In an embodiment, the method includes recovering heat from a natural gas DR plant to generate steam and produce hydrogen by electrolysis. This can be done at several locations in the natural gas DR plant: Heat recovery means may be arranged in the further process gas loop of the natural gas DR plant, particularly upstream of a dust remover, to recover heat from recycled top gas and generate steam which is fed to the electrolysis means. The heat recovery means may be located particularly before the stack of the natural gas DR plant to recover heat from flue gas from a heater reformer means of the process gas loop of the natural gas DR plant to generate steam. Heat recovery means may be arranged to recover heat from the hot DRI (in the form of, for example, HDRI, HBI or CRDI) produced by the natural gas DR plant to produce steam.

[0018] To produce hydrogen by electrolysis, heat can be recovered and steam generated in the same way (at the same location) in the MxCol plant and the NG / H2 plant. The industrial site may generally include an electric arc furnace, EAF, in particular for melting DRI produced at one of the DR plants or elsewhere, where heat recovery means may advantageously be arranged to recover heat from the hot gases / waste heat released by the EAF to generate steam (which is fed to the electrolysis unit).

[0019] In an embodiment, the method includes extracting a CO2-containing gas from the natural gas DR plant and feeding the extracted CO2-containing gas to the gas shift reaction means to produce hydrogen. A first CO2-containing gas stream may be branched off from the process gas loop, preferably downstream of the compressor unit. A second CO2-containing gas stream may be branched off after the dust remover.

[0020] In an embodiment, the method may include recovering heat by one or more heat recovery means located at one or more locations within the hydrogen DR plant, and supplying the produced steam to an electrolysis means. Heat recovery means may also be arranged in the process gas loop of the hydrogen DR plant, particularly upstream of the deduster, to recover heat from the recycled top gas and generate steam that is fed to the electrolysis means. The heat recovery means may be arranged to recover heat from the hot DRI produced in the hydrogen DR plant to generate steam which is fed to the electrolysis means. In general, the heat recovery means may be arranged to recover heat from one or more components within the industrial plant, in particular from the EAF, from one or more DRI heat recovery systems (from any DR plant), and from any DR plant.

[0021] According to another aspect, the present invention provides a method for producing a method of manufacturing a semiconductor device comprising: an industrial plant comprising at least one component that produces a CO2-containing gas, waste heat and / or steam and / or hot gas; 1. A hydrogen direct reduction, DR, plant comprising: a shaft furnace for reducing iron ore in a hydrogen reducing atmosphere; and a process gas loop for receiving top gas from the shaft furnace, treating it before heating it in a heater device, and receiving a hydrogen flow upstream of the heater device to return a reducing gas containing at least 80% hydrogen by volume to the furnace; Hydrogen is produced by: i) electrolysis means configured to produce hydrogen from steam recovered from one or more components of the industrial plant and / or from steam generated by heat recovery means configured to generate steam from waste heat and / or hot gases emitted by one or more components; and ii) a gas shift reaction means configured to convert CO2-containing gases emitted by an industrial plant into hydrogen (preferably with associated CO2 removal); and the hydrogen stream(s) produced by the hydrogen production means are at least partially supplied to a hydrogen DR plant for addition to said process gas loop; Regarding the plant.

[0022] The plant may be generally configured to carry out the method described above. According to another aspect, the present invention relates to a method of operating a hydrogen DR plant, the method comprising recovering heat by heat recovery means located at one or more locations within the hydrogen DR plant, and supplying the steam produced to electrolysis means to produce hydrogen, at least a portion of which is then supplied to a process gas loop of the hydrogen DR plant.

[0023] Heat recovery means may be arranged in the process gas loop of the hydrogen DR plant, particularly upstream of the deduster, to recover heat from the recycled top gas and generate steam which is fed to the electrolysis means. The heat recovery means may be arranged to recover heat from the DRI heat recovery system of the hydrogen DR plant and generate steam that is supplied to the electrolysis means. According to yet another aspect, the invention relates to a system for carrying out the method described above (see also embodiment 4 below). [Brief explanation of the drawings]

[0024] The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which Figures 1 to 4 relate to different embodiments of the invention. [Figure 1] 1 illustrates an embodiment of the present invention. [Figure 2] FIG. 1 illustrates another embodiment of the present invention. [Figure 3] FIG. 1 illustrates another embodiment of the present invention. [Figure 4] FIG. 1 illustrates another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Industrial sites are characterized by the availability of steam and CO-containing gases. In this context, the installation of a fully integrated H direct reduction plant (e.g., MIDREX H) within an existing industrial site is feasible, as in the following embodiment.

[0026] As is evident, the present invention proposes configurations in which DR plants are fully integrated in industrial sites, especially metallurgical plants, with the aim of leveraging synergies within these industrial sites to support the production of H2 by hydrogen DR plants. In the following embodiment, the hydrogen-operated DR plant is for example of the MIDREX H2™ type. In some embodiments, the hydrogen DR plant is installed in a location with a natural gas operated DR plant, for example of the MIDREX NG type.

[0027] Embodiment #1 - See innovative example in Figure 1 Referring now to FIG. 1, a first embodiment of the present invention is shown that integrates an existing metallurgical site 12 with a hydrogen DR plant 10 operating with hydrogen as the reducing gas.

[0028] The DR plant 10 generally corresponds to the MIDREX H2 process. As is known, it comprises a vertical shaft 16 having an upper inlet 18 and a lower outlet 20. A charge of iron ore in lump and / or pellet form is introduced into the top of the furnace and allowed to descend by gravity through the reducing gas. The charge remains in a solid state during its travel from inlet to outlet. Reducing gas (consisting primarily of H2) is introduced laterally into the shaft furnace at the base of the reduction section, as indicated by arrow 22, and flows upward through the ore bed. Reduction of iron oxide occurs in an H2-enriched reducing atmosphere in the upper part of the furnace at temperatures ranging from 850 to 950°C. The solid product, direct reduced iron (DRI) or reduced sponge iron, is discharged either after cooling or hot, as indicated by CDRI (cold DRI), HDRI (hot DRI), and HBI (hot briquetted iron).

[0029] According to the MIDREX H2 process, nearly pure hydrogen is used as the reducing gas in the DR furnace. The ideal hydrogen content of the reducing gas is 100%. In practice, the H2 content can vary between 85 and 100% by volume, with the balance being N2, CO, CO2, H2O, and CH4. These components result from the purity of the H2 make-up and the eventual addition of natural gas as known in the art.

[0030] As known to those skilled in the art, MIDREX H2 is similar to the standard MIDREX natural gas process, except that the H2 input gas is generated external to the process. Thus, there is no reforming process to be performed, only a heat transfer to heat the gas to the required temperature. Because H2 is converted to H2O and condensed in the top gas scrubber, no CO2 removal system is required (except in the case of high NG loadings, as mentioned above).

[0031] Referring to the drawing, the DR furnace 16 is connected to a top gas recycle loop (or process gas loop) 24, which includes a scrubber 26, a compressor unit 28, and a heater unit 30. Thus, the top gas leaving the DR furnace 16 flows through the scrubber 26, where dust is removed and water is condensed before flowing to the compressor unit 28. The amount of hydrogen in the process gas loop 24 is adjusted depending on process requirements by adding a hydrogen stream called "hydrogen make-up." The H content in the hydrogen make-up stream is preferably 90-100%. The hydrogen make-up stream—the hydrogen source is shown in box 32 "Hydrogen Make-up"—is injected into the recycle loop 24 between the compressor unit 28 and the heater unit 30. The gas is then heated in the heater unit 30 to the required temperature range, whereby the reducing gas is ready for introduction into the furnace 16. Heating energy may be supplied to the heater device 30 via environmentally friendly heat sources such as waste heat, electricity, hydrogen, biomass, and / or natural gas required as fuel for the heater device.

[0032] As can be seen from this description, the majority of the hydrogen flow required for the reduction process can be produced on-site and arrives at node 32. If desired, H2 can be added from an external source, but this should typically be only a small portion of the hydrogen flow added to the process gas loop.

[0033] Steam S1 may be recovered from industrial sites 12 where it may be available, or may be produced by standard heat recovery equipment. For example, waste heat may be directed to a heat exchanger (e.g., boiler-type steam production) to produce steam from water.

[0034] The produced and / or recovered steam can be used to feed a feed steam electrolysis unit 3 to produce a hydrogen stream A1 that is directed to the H2 DR plant. Another stream of steam S2 recovered from or produced in the industrial plant 12 may be fed to the water-gas shift reaction plant 1 together with a CO2-containing gas G1 originating from gas produced in a different process present in the plant 12.

[0035] Gas Shift Reaction Plant (GSRP) 1 reacts carbon monoxide with water vapor to form carbon dioxide and hydrogen: CO+H2O⇔CO2+H2 The catalyst is designed to carry out the water-gas shift reaction, denoted by The GSRP1 may be of any suitable technology. It therefore receives two streams (steam S2 and CO2-containing gas G1) from the industrial site 12 and produces two main streams containing carbon dioxide on the one hand and a hydrogen-enriched stream, see stream A2, on the other hand. It will be understood that the GSRP1 is further configured to separate CO2 so that it can be removed from the process. The GSRP plant 1 may be of any suitable conventional technology.

[0036] The hydrogen-rich stream exiting GSRP1 may optionally be passed through a nitrogen removal unit 2 (eg, using membrane or pressure swing adsorption) to separate N2 from the gas stream. The hydrogen stream A2 so produced is fed to node 32 where it is mixed with the first stream A1 and, optionally, with another H2 stream coming from an external source. This combined hydrogen stream is introduced into top gas recycle loop 24. The CO2-containing gas stream G1 may be compressed upstream of the GSRP1 by a compressor unit 34. A pressure recovery system (turbine) 36 may be located downstream of the WGS reactor plant 1 to recover energy from the hydrogen A2 stream and generate electricity to power the compressor 34.

[0037] This integrated solution allows most of the hydrogen required for the H2 reduction process to be met with hydrogen produced in-house within the integrated plant. Those skilled in the art will recognize the potential for heat recovery (i.e., steam produced by heat recovery in the sinter cooler, by coke dry quenching, etc.) in a typical steel plant based on a BF-BOF route. Similarly, those skilled in the art will readily determine the amount and type of CO-containing gases (i.e., BF gas, BOF gas, SAF off-gas, etc.) available in a typical steel plant based on a BF-BOF route.

[0038] A particularly interesting configuration is the DRI-EAF plant shown, which has traditionally been limited to heat recovery, and CO2-containing gases are not commonly available or effectively utilized. Thus, in one embodiment, the present invention utilizes CO-containing gas and waste heat from the EAF to produce H2 through electrolysis and water gas shift reaction, thereby reducing the dependency on external H2 sources to operate the DR plant.

[0039] It should be noted that the configuration of Figure 1 allows selective operation based on steam or CO-containing gas, i.e., the DR plant can be operated using H2 produced from steam generated by heat recovery from industrial sites (i.e., by electrolysis), or H2 produced from CO-containing gas by the GSRP plant, or both.

[0040] Embodiment #2 - Example of Figure 2 Embodiment 2 is a detailed case of embodiment 1 where the H2MIDREX plant 10 is installed within an existing MIDREX NG plant 40.

[0041] As known to those skilled in the art, a MIDREX NG plant 40 conventionally includes a shaft furnace 42 and a top gas recycle loop 44 that includes a top gas scrubber 46, a process gas compressor 48, a heat recovery system 50 and a reformer 52. The arrangement of heat recovery system 50 and reformer 52 shown in Figure 2 is conventional for MIDREX NG facilities, where synthesis gas (primarily CO and H) is formed in reformer 52 by reforming natural gas. CO2-containing recycled top gas is combined with natural gas to form a reducing feed gas for the furnace, preheated in heat recovery system 50, and then reacted in reformer 52 to produce synthesis gas stream SG. Natural gas, a portion of the top gas, and air are combusted in reformer 52 to support the reforming reaction, and the flue gases are passed to the heat recovery system 50 and further downstream to the ambient environment (stack 54).

[0042] It will be appreciated that the steel plant consisting of the NG MIDREX plant 40 and the electric arc furnace 12 has different sources of waste heat available for producing steam to feed the feed steam electrolysis unit 3 and for producing hydrogen shown as stream A1 for use in the MIDREX H2 plant 10.

[0043] Steam generation is achieved by heat recovery / steam generation equipment (e.g., boiler type) located in one or more of the following locations: a heat recovery / steam generation unit 5 producing a steam stream S4 at a top gas outlet (Item 5) on the recycle loop 44; a heat recovery / steam generation unit 6 at the flue gas before the stack 54 inlet, which generates a steam flow S2; a heat recovery / steam generation unit 7 at EAF site 12 that produces a steam stream S1; and a heat recovery / steam generation unit 8 arranged to recover heat from the HBI cooling system and producing a steam stream S5, where heat is extracted from the HBI discharged from the furnace 42, but can also be obtained from heat removed from the CDRI cooling system.

[0044] The various steam streams S1-S5 are combined by mixing nodes 56, 56 to form cumulative stream S6 which is fed to electrolysis unit 3 where hydrogen stream A1 is produced and fed to recycle loop 24 of hydrogen-operated DR plant 10 via node 32 (hydrogen make-up). The total steam produced by the total heat recovery unit allows for the integrated reduction of the required hydrogen make-up from external sources, in varying proportions depending on the size of each MIDREX plant unit. For reference, considering 1 MTPY NG MIDREX, it is possible to save approximately 60-70% of the total metallurgical hydrogen of a 1 MTPY H2MIDREX plant.

[0045] Embodiment #3 - Example of Figure 3 Embodiment 3 represents a more detailed example of embodiment 1 and represents an alternative (or cumulative) example of embodiment 2. Again, the hydrogen DR plant 10 is coupled to the NG DR plant 40. A portion of the CO-containing gas produced by the NG reduction process, here the top gas fuel stream R2 and / or the process gas stream R1, is removed from the NG recycle loop 44 and directed to the GSRP1 to produce hydrogen stream C1 for the H2 reduction process. At least a portion of the CO2 stream B1 produced in GSRP1 is reintroduced into the NG reduction process in order to meet the predetermined CO2 ratio in the reforming step.

[0046] The hydrogen stream C1, optionally combined with hydrogen from another source, is introduced into the top gas recycle loop 24 of the hydrogen DR plant 10 upstream of the heater 30. 1, a compressor 34 is placed before the GSRP1 to compress the CO2-containing streams R1 and R2. Energy can be recovered by an optional pressure recovery turbine 36.

[0047] Table 1 below shows a typical gas composition of the top gas fuel (stream R2) and the process gas (stream R1). [Table 1]

[0048] Embodiment #4 - Example of Figure 4 This last embodiment represents an additional possibility that can be implemented in addition to the previous embodiments. A steel plant including an H2MIDREX plant and an electric arc furnace (EAF) can be part of the in-house production of part of the hydrogen required for the reduction process of the hydrogen DR plant 10 according to the configuration shown in Figure 4. In this embodiment, different heat sources are utilized to produce steam by means of heat recovery / steam generation facilities (e.g. boiler type) located in one or more of the following locations: a heat recovery / steam generation unit 60 at the top gas outlet from the furnace 16 before the inlet of the scrubber 26, which generates a steam stream S7; a heat recovery / steam generation unit 62 at the EAF site, producing a steam stream S9; A heat recovery / steam generation unit 64 in combination with the HBI cooling system to produce a steam stream S8 (also obtained by heat removed from the CDRI cooling system).

[0049] Streams S7, S8 and S9 (possibly together with an additional steam stream from the industrial site network) are combined at mixing node 66 and the resulting steam stream S10 is fed to steam feed electrolysis unit 3 to produce hydrogen stream A1. Heat recovery options (10, 11, and / or 12) and electrolysis units can be easily integrated in the embodiment of FIG.

[0050] advantage Opex / Capex benefits Conventional operation of H2DR plants currently suffers from high operational costs (and capital expenditures) for hydrogen production or purchase from off-plant sources. The present invention provides a technically flexible solution as it can provide benefits both now and in the near future as market conditions change. If current steam electrolysis units cannot be made cost-effective overall at current electricity prices, they can minimize or eliminate their contribution to processes that emphasize water-gas shift technology, which appears to be the most attractive option for producing hydrogen at the lowest operational cost compared to current market purchased industrial hydrogen and electrolysis-based hydrogen products.

[0051] Electricity prices will fall in the near future. Steam electrolysis solutions will become the most convenient way to produce hydrogen. The versatility of this embodiment provides the opportunity to utilize two different technologies depending on the most favorable market environment. Therefore, considering that home-produced hydrogen can meet various process requirements depending on the process characteristics and plant size, the innovative plant configuration described above can reduce the costs associated with current and future hydrogen utilization.

[0052] Environmental benefits The proposed solution is based on CO2-containing gas and / or feed steam electrolysis. When using feed steam electrolysis, it can be claimed that the produced hydrogen (if electricity is produced as a result) is CO2-free. When using CO2-containing gases, it can be argued that hydrogen is at least CO2-neutral (as no additional CO2 is released and no additional fossil fuels are required - i.e. compared to steam methane reforming).

Claims

1. operating a hydrogen direct reduction (DR) plant wherein the shaft furnace is connected to a process gas loop arranged to receive top gas from the shaft furnace, treating the top gas before heating it with a heater device, and wherein a hydrogen flow is added to the process gas loop upstream of the heater device to return a reducing gas containing at least 85% by volume of hydrogen to the furnace, so that the iron ore is reduced in the hydrogen-enriched atmosphere in the shaft furnace; an industrial plant comprising a natural gas DR plant operating on reformed natural gas to produce DRI from iron ore, said natural gas DR plant comprising a further shaft furnace and a further process gas loop, said further process gas loop comprising a heater and reforming means for producing synthesis gas from the natural gas which is fed to the further shaft furnace as reducing gas, and operating the industrial plant to produce CO2-containing gas and / or waste heat and / or high-temperature gas; Including, At least a portion of the hydrogen stream electrolysis means configured to produce hydrogen from steam recovered from one or more components of the industrial plant and / or from steam generated using waste heat and / or hot gases released by one or more components; and Converting CO2-containing gases released by at least one component of an industrial plant into hydrogen and CO2 ２ a gas shift reaction means configured to remove Manufactured by at least one of A method for producing direct reduced iron, DRI.

2. 10. The method of claim 1, including recovering heat from a natural gas DR plant to generate steam and produce hydrogen in said electrolysis means.

3. 3. The method of claim 2, wherein a heat recovery means is arranged in the further process gas loop of the natural gas DR plant, in particular in contact with the top gas after it leaves the shaft furnace, to recover heat from the recycled top gas and generate steam to be fed to the electrolysis means.

4. 4. The method according to claim 2 or 3, wherein a heat recovery means is arranged in particular before the stack of the natural gas DR plant for recovering heat from flue gas from a heater reforming means of the process gas loop of the natural gas DR plant to generate steam.

5. 5. The method of claim 2, 3 or 4, wherein heat recovery means is arranged to recover heat from the hot DRI produced in the natural gas DR plant to produce steam.

6. 6. A method according to any one of claims 1 to 5, wherein the industrial plant comprises an EAF and heat recovery means are arranged to recover heat from waste heat and / or hot gases released by the EAF to produce steam, and possibly to recover heat from downstream equipment.

7. extracting a CO2-containing gas from the natural gas DR plant; and supplying the extracted CO2-containing gas to the gas shift reaction means; 7. The method of any one of claims 1 to 6, wherein a first CO2-containing gas stream is extracted from the process gas loop downstream of the compressor means and / or a second CO2-containing gas stream is extracted after the dedusting device in the process gas loop.

8. 8. The method of any one of claims 1 to 7, comprising recovering heat by heat recovery means located at one or more locations within the hydrogen DR plant, and supplying the steam produced to electrolysis means.

9. 9. The method according to claim 8, wherein heat recovery means are arranged in the further process gas loop of the hydrogen DR plant, in particular in contact with top gas after it leaves the further shaft furnace, to recover heat from recycled top gas and generate steam which is fed to the electrolysis means.

10. 10. The method of claim 8 or 9, wherein heat recovery means is arranged to recover heat from the hot DRI produced in the hydrogen DR plant to generate steam which is supplied to the electrolysis means.

11. 11. The method of any one of claims 1 to 10, wherein the industrial plant comprises one or more of a sinter plant, a coke oven plant, an electric arc furnace, a blast furnace, a submerged arc furnace (SAF), a continuous caster, a rolling mill, and a basic oxygen furnace.

12. 12. The method of any one of claims 1 to 11, wherein the process gas loop includes gas purification means and compressor means upstream of the heater device, and the addition of the hydrogen flow occurs between the compressor means and the heater device.

13. The hydrogen stream added to the process gas loop of the hydrogen DR plant is 90-100% by volume H ２ and optionally hydrogen from a further source is supplied to the hydrogen DR plant.

14. an industrial plant comprising at least one component that produces a CO2-containing gas, waste heat and / or steam and / or hot gas; a hydrogen direct reduction (DR) plant comprising: a shaft furnace for reducing iron ore in a hydrogen reducing atmosphere; and a process gas loop for receiving top gas from the shaft furnace and treating it before heating it in a heater device and receiving a hydrogen flow upstream of said heater device to return a reducing gas containing at least 80% by volume of hydrogen to the furnace; A plant comprising: The hydrogen production means is electrolysis means configured to produce hydrogen from steam recovered from one or more components of the industrial plant and / or from steam generated by heat recovery means configured to generate steam from waste heat and / or hot gases emitted by one or more components; Converting CO-containing gases released by industrial plants into hydrogen and CO ２ a gas shift reaction means configured to remove and the hydrogen stream(s) produced by the hydrogen production means are at least partially supplied to a hydrogen DR plant for addition to said process gas loop; The industrial plant includes a natural gas DR plant operating on reformed natural gas to produce DRI from iron ore, the natural gas DR plant including a further shaft furnace and a further process gas loop, the further process gas loop including heater and reforming means for producing synthesis gas from the natural gas which is supplied to the further shaft furnace as a reducing gas. plant.

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