Method of operating an electric arc furnace and steel mill having an electric arc furnace

Abstract

The present invention provides a method for operating an electric arc furnace, comprising capturing heated metallurgical gas comprising water and carbon monoxide from at least one facility of a steel plant; conveying the metallurgical gas to a reactor via a reactor supply line; converting carbon monoxide and water into hydrogen and carbon dioxide by treating the metallurgical gas within the reactor according to a water-gas shift reaction; and subsequently separating the hydrogen by a separation device; the method is characterized by supplying an iron-containing material to the electric arc furnace, the iron-containing material comprising iron primarily in the form of iron oxide; at least partially melting the iron-containing material to obtain a molten pool; conveying hydrogen to the electric arc furnace via a furnace supply line, the electric arc furnace being arranged downstream of the furnace supply line; and injecting hydrogen into the molten pool in the electric arc furnace by means of a plurality of hydrogen injection devices, such that during the smelting operation of the electric arc furnace, the hydrogen acts as a reducing agent for reducing the iron oxide in the molten pool.

Description

[Technical Field]

[0001] This invention relates to a method for operating an electric arc furnace, an electric arc furnace, and a steel plant. [Previous Technology]

[0002] Modern steel mills (such as steel and metal production facilities) are constrained by the need to reduce carbon dioxide emissions. For this reason, steel companies use so-called "green" electricity or "renewable" fuels instead of fossil fuels used in their production facilities. Against this backdrop, hydrogen is used as a fuel, and is therefore considered a key factor in reducing CO2 emissions. However, the production, transportation, and storage of large quantities of hydrogen present considerable technical challenges and are accompanied by high costs. For this reason, existing technologies often focus on the economic aspects of hydrogen production or methods for replacing fossil fuels with hydrogen in production.

[0003] The main integrated hydrogen production process is steam reforming and electrolysis of natural gas. Steam reforming of natural gas is currently considered the most common and cheapest source of industrial hydrogen. Natural gas (methane) is heated to 700–1100°C in the presence of steam and a nickel catalyst. Methane molecules crack, forming carbon monoxide and hydrogen. The carbon monoxide gas is passed through iron oxide or other oxides along with the steam, and additional hydrogen is obtained due to a reaction known as the water-gas shift reaction. Hydrogen produced in this way is economically attractive, but still requires fossil fuels. To completely avoid CO2 emissions during hydrogen production, CO2 must be captured and stored. In electrolysis, hydrogen is produced by a cell consisting of several batteries, each with an anode and cathode immersed in an electrolyte solution and connected to a power source.

[0004] However, both steam reforming and electrolysis are quite expensive and require large amounts of energy, as well as large-scale and secure infrastructure for the transportation and storage of hydrogen. If one of these methods is set up to operate in an industrial environment, primarily for safety reasons, the corresponding production facilities are typically completely isolated from high-temperature areas. This has a significant drawback: valuable resources, such as space and energy, may be used inefficiently in such locations and settings.

[0005] In the prior art, there are electric arc furnaces (EAFs) used to produce steel from a charge mixture typically consisting of scrap metal and hot metal, wherein the EAF primarily performs the melting process. If the charge mixture contains iron oxide, the EAF can also reduce this iron oxide.

[0006] However, due to process limitations, such reduction can only be carried out in limited quantities. Such EAFs typically require a filler mixture with a high degree of metallization. For this reason, if iron oxide is included in the EAF feed, the iron oxide is typically derived from direct reduced iron (DRI) with a metallization degree higher than 88%, which is produced from a prior gas based on a direct reduction process. Such EAFs are called "directly heated" because they generate highly concentrated heat, which is released by an electric arc formed between the electrode and the molten material.

[0007] Another type of electric furnace, known as a submerged arc furnace (SAF), has been developed for the reduction and melting of metal oxides. These SAFs can perform a complete reduction process starting from metal ores such as nickel, chromium, copper, or iron. In an SAF, the electrodes are immersed in the upper part of the molten material (e.g., in slag or a molten pool), thus utilizing a Joule-based heating principle derived from the current generated by the electrodes within the high-resistivity slag. Typically, the process parameters in an SAF differ from those in an EAF. SAFs allow for a complete reduction process from iron or other metal ores.

[0008] The reduction process in EAF and SAF is carried out using carbon (usually in the form of coke or anthracite) as a reducing agent, which can be injected (or injected) by a suitable spray gun or loaded from a top charging system.

[0009] When the material to be melted includes pre-reduced iron pellets, direct reduced iron (DRI), or hot briquetted iron (HBI), some of the carbon required for the reduction process is already included in the DRI or HBI pellets. Therefore, the reduction reaction in the EAF proceeds through both the injected carbon and the carbon present in the direct reduced iron.

[0010] Carbon not only acts as a reducing agent in EAF and SAF, but is also required to maintain appropriate process conditions in terms of reaction kinetics, total energy balance, heat transfer coefficient and process yield.

[0011] Therefore, such a furnace has the disadvantage of releasing a relatively large amount of carbon dioxide during its operation. [Summary of the Invention]

[0012] Therefore, the object of the present invention is to provide a method for operating an electric arc furnace in a steel plant, wherein carbon dioxide emissions are significantly reduced.

[0013] This objective is achieved through the content of a separate request item.

[0014] The present invention provides a method for operating an electric arc furnace, the method comprising: capturing heated metallurgical gas comprising water and carbon monoxide from at least one facility of a steel plant; conveying the metallurgical gas to a reactor via a reactor supply line; the method further comprising, according to a water-gas shift reaction, treating the metallurgical gas within the reactor to convert carbon monoxide and water comprising the metallurgical gas into hydrogen and carbon dioxide, and subsequently separating the hydrogen by a separation device; the method further comprising supplying an iron-containing material to the electric arc furnace, the iron-containing material comprising primarily iron in the form of iron oxide; at least partially melting the iron-containing material to obtain a molten pool; conveying the hydrogen via a furnace supply line to the electric arc furnace arranged downstream of the furnace supply line; and injecting the hydrogen into the molten pool in the electric arc furnace by means of a plurality of hydrogen injection devices, such that during the smelting operation of the electric arc furnace, the hydrogen acts as a reducing agent for reducing the iron oxide in the molten pool.

[0015] This method is based on the finding that hydrogen can be produced and used in steel plants in a more sustainable and environmentally friendly manner, and advantageously, hydrogen can be used as a reducing agent in electric arc furnaces operating as electric melting units. It has been found that hydrogen (H2) can be separated from various metallurgical gases emitted from different field facilities (such as steel plant facilities). For example, hydrogen can be obtained / produced by utilizing a water-gas shift reaction, by injecting steam into a CO-rich gas (such as blast furnace gas).

[0016] "Metallurgical gases" generally refers to any gas emitted from a metallurgical facility, such as a (blast) furnace, coke oven, or similar facility. Metallurgical gases form the basis of what is called syngas (or synthetic gas), a mixture of fuel gases that primarily consists of hydrogen, carbon monoxide, and very often some carbon dioxide.

[0017] Specifically, this method aims to utilize the availability of syngas comprising hydrogen and / or carbon monoxide in steel plants, wherein the carbon monoxide is used to separate hydrogen via steam. Syngas can be obtained from metallurgical gas according to known techniques, for example, by performing a carbon dissolution loss reaction (Boudouard reaction) and / or a water-gas shift reaction. Alternatively, hydrogen can also be produced by other processes, such as, for example, natural gas reforming, biomass reforming, or steam reforming. An example of metallurgical gas is blast furnace gas. Blast furnace gas comprises approximately 20 to 30 vol% CO2, approximately 35 to 50 vol% N2, and approximately 20 to 30 vol% CO and approximately 5% H2, or consists of the foregoing. Another example of metallurgical gas is what is known as "converter gas". Converter gas comprises approximately 60 to 70% CO, approximately 10 to 20% CO2, approximately 0-5% H2, and approximately 5 to 15% N2, or is composed of the foregoing. Another example of metallurgical gas is "coke oven gas." Coke oven gas comprises approximately 5 to 10% CO, approximately 50 to 55% H2, approximately 20% CH4 and / or other hydrocarbons, approximately 10% or less N2, and a small amount of CO2, or is composed of the foregoing. It should be noted that this composition and the exemplary percentages can vary significantly depending on process conditions. Metallurgical gas can be mixed with steam for heating and / or water addition.

[0018] Metallurgical gas can be treated by conventionally known methods to separate hydrogen from other compounds. For example, water gas shift (WGS) reactions and / or carbon dioxide removal methods can be used to convert carbon monoxide (CO), which forms part of the metallurgical gas, into carbon dioxide. The carbon dioxide is then easily (more easily than carbon monoxide) separated from the metallurgical gas, such that the remaining metallurgical gas contains a large amount of hydrogen (or a particularly high concentration of hydrogen).

[0019] It has been further discovered that recovering hydrogen gas by separating it from gases emitted from existing processes and facilities allows for the provision, maintenance and operation of electric arc furnaces in a particularly economical and environmentally friendly manner.

[0020] This method is also based on the discovery that the hydrogen can be directed into an electric arc furnace (EAF), whereby the hydrogen is injected into the molten pool (or slag), thereby operating the EAF as an electrosmelting apparatus. During such EAF operation, the hydrogen is used as a reducing agent instead of carbon during the production of steel from iron-containing materials primarily in the form of iron oxide. Therefore, the amount of carbon dioxide emitted from such an EAF and from the metallurgical equipment can be significantly reduced. "Primarily" herein means that more than 50% by weight, preferably at least 60% by weight, such as at least 70%, at least 80%, or even more than 85% by weight, of the iron-containing material is in the form of iron oxide.

[0021] An "electric arc furnace" generally refers to an industrial furnace constructed for a melting process using an electric arc. The electric arc in an electric arc furnace is generated between electrodes or between electrodes and the molten material (such as a molten metal pool or slag). An electric arc furnace can be constructed to provide the preparation conditions required for operating and maintaining a reduction process using hydrogen. These preparation conditions can be characterized by parameters such as pressure, temperature, kinetics, heat transfer coefficient, or similar parameters. An electric arc furnace can be powered by direct current or alternating current.

[0022] "Facilities" generally means the whole of any industrial installation or equipment built, installed or constructed for a particular purpose. For example, facilities may include blast furnaces, coke oven groups or hot blast stoves or consist of the foregoing.

[0023] "Steel mill" (or "steel plant") usually refers to an industrial facility that manufactures iron and steel and / or metals.

[0024] A "reactor" generally refers to a device used as a container / bucket / receiver for a chemical reaction. A reactor may also include multiple containers separated from each other, for example by a (semi)permeable filter or catalyst. For example, a reactor may be configured to convert carbon monoxide and water contained in metallurgical gas into hydrogen and carbon dioxide.

[0025] “Furnace supply line” usually refers to a gas pipeline that transports gas, especially hydrogen, into a furnace (e.g., an electric arc furnace).

[0026] "Reducing agent" generally refers to a substance that reduces a chemical compound by providing electrons. In existing electric arc furnaces, the injection of coal allows for the reduction of iron oxide in the slag. Carbon monoxide, also present in the melt, slag, or molten pool within the electric arc furnace, can also act as a reducing agent for iron oxide. The reduction reaction within the EAF can be based on hydrogen and electrical energy. Therefore, hydrogen can completely or at least partially replace carbon as a reducing agent, preferably up to at least 25 mol.-%, advantageously up to at least 50%, preferably up to at least 60%, such as up to at least 70%, up to at least 80%, or even up to almost 100 mol.-%. In other words, carbon, currently used as a reducing agent in very advanced electric arc furnaces, can be partially or completely replaced by hydrogen. Carbon dioxide emissions can be completely prevented or at least significantly reduced.

[0027] "Conduction" generally refers to the action of guiding, transporting, or transmitting gas, usually by providing conduits or channels in the form of, for example, pipes, tubes, pipelines, (gas) lines, or similar technical components. "Reactor supply line" generally refers to a gas pipeline that supplies gas to the reactor.

[0028] "Capture" generally refers to the process of separating, isolating, storing, absorbing, capturing, trapping, and / or preventing the emission or release of gases into the external environment (such as, for example, the atmosphere). For example, metallurgical gas emitted from a blast furnace can be captured by suitable filters and / or separation equipment.

[0029] "Injection" generally refers to the introduction of a gas into a facility (such as, for example, an EAF) or into a mixture of melt or compound (e.g., slag) within a facility. Injection can be performed by an injection device. "Injection device" generally refers to any device used or configured for injecting a gas (such as, for example, hydrogen or oxygen) into a facility or into a mixture of melt or compound within a facility. For example, an injection device may be immersed in a molten pool.

[0030] “Operation” usually refers to a functioning action.

[0031] "Smelting" generally refers to the process of melting and reducing a metallic material, such as a metal ore, or an iron-containing material that includes iron mainly in the form of iron oxide. This process results in chemical changes or reactions in the molten state, such as the separation of metals (such as metallic iron).

[0032] "Separation" generally refers to the action of separating gaseous components from a gas mixture. For example, after metallurgical gas has been converted into hydrogen, carbon dioxide, and possibly other byproducts in a reactor, the hydrogen can be separated from the mixture, for example, by means of a filter or membrane. Furthermore, separation can also be carried out by known processes, such as gas separation methods based on cryogenic distillation, pressure swing adsorption, Hampson-Linde cycles, or similar separation methods. "Separation apparatus" generally refers to equipment or a group of connected devices used for or constructed for operating a separation step or separation method.

[0033] "Transformation" usually refers to a change in the composition, structure, form or appearance of one or more substances (e.g., a mixture of gases).

[0034] "To treat" or "to process" generally refers to subjecting something to the influence or process of a reagent, catalyst, energy, chemical, biological or physical agent. For example, treatment may include directing metallurgical gas to a heated catalyst within a reactor.

[0035] In some embodiments, after relevant gas purification, the metallurgical gas has a temperature in the range of 20°C to 100°C. It has been found that the metallurgical gas can be preheated in a suitable heat recovery system, utilizing some available heat from other processes within the integrated steel industry, and can be converted in a particularly energy-efficient manner in subsequent reactions. The metallurgical gas is typically available at temperatures between 20°C and 100°C, preferably below 50°C. The metallurgical gas can be stored in a gas storage device after gas purification, such as gas purification in a scrubbing unit. It should be noted that, depending on its composition, these heated metallurgical gases can be processed using known heat recovery methods.

[0036] Processes for converting carbon monoxide and water into hydrogen and carbon dioxide include at least a water-gas shift reaction, wherein the reaction is carried out in the presence of a catalyst. A "water-gas shift reaction" (or water-gas conversion reaction) is a process used to reduce / decrease the carbon monoxide content in syngas and produce hydrogen. The reaction equation is also known as the conversion equilibrium: CO + H₂O ↔ CO₂ + H₂.

[0037] In some embodiments, the method further includes, after separating the hydrogen, conveying the hydrogen to a hydrogen storage tank via a storage supply conduit. A “storage supply conduit” generally refers to a pipe used or configured to introduce the hydrogen into a hydrogen (storage) tank.

[0038] In some embodiments, the method further includes discharging the hydrogen from the hydrogen storage tank to the electric arc furnace via a furnace supply line.

[0039] In some embodiments, the method further includes heating the hydrogen upstream of the electric arc furnace such that the hydrogen has a temperature in the range of 25°C to 700°C when it is injected into the electric arc furnace. Heating the hydrogen increases the pressure and thus improves the distribution of the injected hydrogen in the molten pool. It should be noted that "heating" can also refer to the process of preheating the hydrogen gas before injecting it into the EAF.

[0040] In some embodiments, the plurality of hydrogen injection devices include at least one supersonic gas nozzle for injecting at least a portion of the hydrogen supplied to the electric arc furnace into the furnace. In other words, the gas is injected at supersonic speed.

[0041] In some embodiments, the hydrogen injected via a supersonic gas jet has a throughput in the range of 10 m3 / min to 500 m3 / min.

[0042] In some embodiments, the method further includes injecting oxygen into the electric arc furnace via multiple oxygen injection devices. Oxygen can be injected to oxidize iron at least partially within the molten pool (or within the slag). In other words, using the heat released by the exothermic reaction, oxygen in the molten pool oxidizes at least a small amount of iron into wüstite (FeO, ferrous oxide), which is locally necessary to maintain the necessary preparation conditions.

[0043] In some embodiments, the method further includes introducing lime into the electric arc furnace by a lime introduction device. "Lime introduction device" generally refers to any device used or configured for introducing (e.g., injecting) lime into the electric arc furnace or a layer of slag within the electric arc furnace. For example, the lime may include quicklime or be composed of quicklime. Lime can be used as a flux for cleaning steel in an electric arc furnace (EAF). For example, lime can be used to remove sulfur, silicon dioxide, phosphorus, and similar substances.

[0044] In some embodiments, the method further includes inserting / introducing material into the electric arc furnace, wherein the material comprises at least one of the following: iron oxide, pre-reduced iron ore pellets, direct reduced iron (DRI), hot-pressed iron briquettes (HBI), blast furnace grade, DR (direct reduced) grade iron ore pellets or powders, or mixtures thereof. For example, a small amount of carbon can be provided by direct reduced iron in the form of cold pellets or hot-pressed briquettes, which can be used to heat the melt. These reduced irons can be produced by a natural gas-based direct reduction process.

[0045] In some embodiments, the method further includes supplying electrical energy to the electric arc furnace, wherein the electrical energy is used to operate the EAF, and wherein the electrical energy is obtained from renewable energy sources. "Renewable energy sources" generally refers to energy sources that provide electrical energy based on at least one of the following: solar energy, wind energy, hydropower, biomass energy, geothermal energy, tidal energy, and wave energy, or a combination thereof. Due to the use of renewable energy sources, this method allows for the production of "green steel," which is largely or completely CO2-free if only iron ore and / or DRI / HBI from a hydrogen-based direct reduction process are charged as iron-containing materials in the EAF.

[0046] The present invention also relates to a steel plant, which includes an electric arc furnace and is suitable for:

[0047] - Capture heated metallurgical gas, including water and carbon monoxide, from at least one facility in a steel plant;

[0048] - The metallurgical gas is transported to the reactor via a reactor supply pipeline;

[0049] - According to the water-gas shift reaction, carbon monoxide and water are converted into hydrogen and carbon dioxide by treating the metallurgical gas in the reactor; and subsequently...

[0050] - The hydrogen gas is separated by a separation device;

[0051] This steel plant is suitable for:

[0052] - Providing an iron-containing material to an electric arc furnace, the iron-containing material comprising iron primarily in the form of iron oxide;

[0053] - At least partially melt the iron-containing material to obtain a molten pool;

[0054] - The hydrogen gas is conveyed to the electric arc furnace via a furnace supply line, the electric arc furnace being arranged downstream of the furnace supply line; and

[0055] - Hydrogen is injected into the molten pool in the electric arc furnace via multiple hydrogen injection devices, such that during the melting operation of the electric arc furnace, the hydrogen acts as a reducing agent to reduce iron oxide in the molten pool. The above-described modifications and embodiments of the method according to the invention are also applicable to steel mills.

[0056] Other aspects and features of the invention may be found in the following description of the appended claims, drawings and embodiments.

Implementation Method

[0058] Figure 1 illustrates a schematic diagram of the method according to the invention, as well as an electric arc furnace 10 and a steel plant 100. The steel plant 100 includes a facility 12 consisting of a blast furnace 12, which emits heated metallurgical gas containing water and carbon monoxide. The gas from the blast furnace has a temperature in the range of approximately 200°C to 300°C. The metallurgical gas can be cleaned by a scrubber and stored in a gas storage tank (not shown). As shown in Figure 1, the metallurgical gas emitted from the blast furnace 12 is captured and directed to a reactor 16 by / through a reactor supply line 14. The metallurgical gas must be preheated for use in the hydrogen production process, for example by mixing the metallurgical gas with steam (not shown), wherein the steam provides the heat and water required for the water-gas shift reaction.

[0059] Additional devices (not shown), such as temperature sensors, pressure sensors, flow meters, and (automatic) valves, may be arranged on and / or within the reactor supply line 14. These additional devices may be connected to a control unit, such as, for example, a computer (not shown). The control unit may be configured to determine process parameters related to the metallurgical gas, such as, for example, the temperature, pressure, and / or velocity of the metallurgical gas. Depending on these process parameters, the control unit may, via software, determine whether the valves arranged within the reactor supply line 14 should be fully open, partially open, or closed.

[0060] Metallurgical gas supplied through reactor supply line 14 is introduced into reactor 16, where carbon monoxide and water compounds in the metallurgical gas are converted into carbon dioxide and hydrogen. The conversion of carbon monoxide and water into hydrogen and carbon dioxide is based on a water-gas shift reaction in the presence of a catalyst, such as, for example, a nickel-based catalyst (not shown). Prior to processing the metallurgical gas in the reactor, additional steps may be performed upstream of the reactor to heat the gas and / or separate substances from the metallurgical gas that would otherwise be harmful to the catalyst (not shown), such as, for example, gaseous sulfur compounds.

[0061] After the gas has been processed in the reactor, it is conveyed to a separation unit 18, where the hydrogen is separated from other compounds in the metallurgical gas. In a subsequent step, the hydrogen is either led directly from the furnace supply line 20 to an electric arc furnace located downstream of the furnace supply line 20, or via a supply conduit 22 to a hydrogen storage tank 24. To operate the passage of the hydrogen toward the tank 24 and / or the electric arc furnace 10, (automatic) valves are arranged in the supply conduit 22 and the furnace supply line 20 (not shown). The valves include computer-operated actuators. Furthermore, both the furnace supply line 20 and the supply conduit 22 include pressure sensors, flow meters, and temperature sensors (not shown) connected to a computer. Depending on the requirements of the electric arc furnace 10, the hydrogen is either conveyed directly to the furnace or to the storage tank 24. If the hydrogen is stored in the tank 24, it can be released into the electric arc furnace at a predetermined rate and / or volume. As can be further seen from Figure 1, the discharge line 23 for the hydrogen discharge is in fluid communication with the furnace supply line 20. The discharge line 23 includes a temperature sensor, a flow meter, a pressure sensor, and a (automatic) valve, each of which is connected to and operated by a control unit (not shown).

[0062] In addition, the furnace supply line 20 may include an optional heating arrangement (not shown), which is also computer-controlled. The heating arrangement allows the hydrogen to be heated upstream of the electric arc furnace such that when the hydrogen is injected into the electric arc furnace, the hydrogen has a temperature in the range of 25°C to 700°C.

[0063] As shown in more detail in Figure 2, the hydrogen gas is injected into the electric arc furnace 10 through / by multiple injection devices 26. Two horizontal dashed lines on the inner side of the furnace symbolize the boundary between the slag zone (layer) 34 and the liquid metal zone 36. During operation of the electric arc furnace, the slag layer 34 forms on the surface near the electrode (not shown). After the electric arc furnace 10 has been operating for a certain period, a liquid metal layer 36 is formed below the slag layer 34. The EAF electrode protrudes from the top (e.g., from the furnace hat (not shown)) into the slag. In other words, the electrode is at least partially immersed in the slag.

[0064] The plurality of hydrogen injection devices 26 also include a supersonic gas nozzle 28, which protrudes from the top of the furnace (such as the furnace cover) into the liquid metal zone 36. During the operation of the EAF, hydrogen is injected via the supersonic gas nozzle 28 at a rate preferably in the range of 10 m3 / min to 500 m3 / min.

[0065] In addition, the electric arc furnace 10 is also provided with a plurality of oxygen injection devices 30 (such as spray guns) for injecting oxygen into the electric arc furnace 10. The oxygen injection devices 30 are spaced apart from the hydrogen injection device 26 and the supersonic gas spray gun 28. It should be noted that the oxygen injection device 26 may also include or be composed of a supersonic gas spray gun.

[0066] As further shown in Figure 2, the lime introduction device 32 protrudes into the liquid metal zone 32 of the electric arc furnace at the interface between the liquid metal zone 32 and the slag zone 34. During operation of the electric arc furnace, the lime introduction device 32 provides lime injection.

[0067] During operation of the electric arc furnace, material is inserted into the hearth of the furnace. This material may include at least one of the following: scrap iron, iron oxide, pre-reduced iron ore pellets, direct reduced iron (DRI), hot-pressed iron ore (HBI), blast furnace grade, DR grade iron ore pellets or powder, or mixtures thereof. The electric arc furnace is powered by electricity derived from renewable energy sources.

[0068] According to the following reaction equation, the injected hydrogen gas is used to reduce iron oxide (e.g., FeO) to iron (Fe) and water:

[0069] FeO + H2↔ Fe + H2O.

[0070] Furthermore, according to the following equation, the injected hydrogen also reacts with oxygen and releases heat:

[0071] H2+ ½ O2→ H2O.

[0072] According to the following equation, the injected oxygen is used to treat iron oxide (Fe):

[0073] Fe + ½ O2 → FeO.

[0074] As can be understood from Figure 2, during the operation of the electric arc furnace 10, the amount of carbon dioxide is completely or at least significantly reduced.

[0075] The embodiments discussed are examples of the invention. The components described in each separate embodiment represent each individual feature of the invention and should be considered independent of each other. Therefore, features should also be considered as part of the invention, whether individually or in combinations different from those shown. Furthermore, the described embodiments may be supplemented by other features of the invention already described.

[0076] Other features and embodiments of the invention will be apparent to those skilled in the art in the context of this disclosure and claims.

[0077] Although the technical content of the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications and refinements made by those skilled in the art without departing from the spirit of the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0057] Figure 1 is a schematic diagram of the method, electric arc furnace, and steel plant according to the present invention. Figure 2 is a schematic diagram of the electric arc furnace according to the present invention.

Claims

1. A method for operating an electric arc furnace (10), the method comprising: Heated metallurgical gas comprising water and carbon monoxide is captured from at least one facility (12) of a steel plant (100); the metallurgical gas is conveyed to a reactor (16) via a reactor supply line (14); the carbon monoxide and water are converted into hydrogen and carbon dioxide by treating the metallurgical gas in the reactor (16) according to a water-gas shift reaction; and the hydrogen is subsequently separated by a separation device (18); characterized in that the method further comprises: supplying an iron-containing material to the electric arc furnace (10), the iron-containing material comprising iron primarily in the form of iron oxide; melting the iron-containing material at least partially to obtain a molten pool; The hydrogen is supplied to the electric arc furnace (10) via a furnace supply line (20), which is located downstream of the furnace supply line (20); and the hydrogen is injected into the molten pool in the electric arc furnace (10) by a plurality of hydrogen injection devices (26), such that during the smelting operation of the electric arc furnace (10), the hydrogen acts as a reducing agent to reduce the iron oxide in the molten pool.

2. The method as claimed in claim 1, wherein the heated metallurgical gas has a temperature in the range of 20°C to 100°C.

3. The method as described in claim 1 or 2 above, wherein the process for converting carbon monoxide and water into hydrogen and carbon dioxide includes at least a water-gas shift reaction, wherein, The reaction is carried out in the presence of a catalyst.

4. The method as described in claim 1 or 2 above, wherein, The method also includes transporting the hydrogen gas to a hydrogen storage tank (24) via a storage supply conduit (22).

5. The method as described in claim 4, wherein, The method also includes discharging the hydrogen from the hydrogen storage tank (24) to the electric arc furnace (10) via the furnace supply line (20).

6. The method as described in claim 1 or 2 above, wherein, The method also includes heating the hydrogen upstream of the electric arc furnace such that the hydrogen has a temperature in the range of 25°C to 700°C when it is injected into the electric arc furnace.

7. The method as described in claim 1 or 2 above, wherein, The plurality of hydrogen injection devices (26) include at least one supersonic gas nozzle (28) for injecting at least a portion of the hydrogen supplied to the electric arc furnace (10) into the furnace.

8. The method as described in request item 7, wherein, The hydrogen injected via the supersonic gas nozzle (28) has a throughput in the range of 10 m3 / min to 500 m3 / min.

9. The method as described in claim 1 or 2 above, wherein, The method also includes injecting oxygen into the electric arc furnace (10) through multiple oxygen injection devices (30).

10. The method as described in claim 1 or 2 above, wherein, The method also includes introducing lime into the electric arc furnace (10) by a lime introduction device (32).

11. The method as described in claim 1 or 2 above, wherein, The method further includes inserting material into the electric arc furnace, wherein the material comprises at least one of the following: iron oxide, pre-reduced iron ore pellets, direct reduced iron (DRI), hot briquette iron briquettes (HBI), blast furnace grade, direct reduced (DR) grade iron ore pellets or powders, or mixtures thereof.

12. The method as described in claim 1 or 2 above, wherein, The method also includes operating the electric arc furnace by obtaining electrical energy from renewable energy sources.

13. A steel plant (100), comprising an electric arc furnace (10) and adapted to: capture heated metallurgical gas comprising water and carbon monoxide from at least one facility (12) of the steel plant (100); transport the metallurgical gas to a reactor (16) via a reactor supply line (14); convert the carbon monoxide and water into hydrogen and carbon dioxide by treating the metallurgical gas in the reactor (16) according to a water-gas shift reaction; and subsequently separate the hydrogen by a separation device (18); characterized in that the steel plant (100) is adapted to: supply the electric arc furnace (10) with an iron-containing material comprising primarily iron in the form of iron oxide; and at least partially melt the iron-containing material to obtain a molten pool; The hydrogen is supplied to the electric arc furnace (10) via a furnace supply line (20), which is located downstream of the furnace supply line (20); and the hydrogen is injected into the molten pool in the electric arc furnace (10) by a plurality of hydrogen injection devices (26), such that during the smelting operation of the electric arc furnace (10), the hydrogen acts as a reducing agent to reduce the iron oxide in the molten pool.

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