Materials based on the reduction of metal oxides by ammonia (NH3) and carbon-containing gases

Abstract

A method for reducing a material containing metal oxides, wherein a reducing gas obtained by utilizing ammonia (NH3) and a carbon-containing gas is used, and a mixture containing ammonia and a carbon-containing gas is prepared during the production of the reducing gas. At least a portion of the mixture is first subjected to ammonia cracking conditions at a temperature up to 650°C, thereby producing a cracked gas mixture. Then, at least a portion of the cracked gas mixture is subjected to reforming conditions at a temperature down to 700°C. The apparatus for this purpose includes a reduction unit (30), a reducing gas input line (40) into the reduction unit (30), a carbon-containing gas supply line (50), and an ammonia supply line (60), and is characterized in that the carbon-containing gas supply line (50) and the ammonia supply line (60) are connected to a mixture line (70), and the mixture line (70) is connected to an ammonia cracking unit (80), and a cracked gas mixture line (90) extends from the ammonia cracking unit (80), the cracked gas mixture line (90) is connected to a reforming unit (100), and a reformed gas line (110) extends from the reforming unit (100), the reformed gas line (110) is connected to the reducing gas input line (40).

Description

Technical Field

[0001] This application relates to a method and apparatus for reducing materials containing metal oxides, wherein a reducing gas obtained by utilizing ammonia (NH3) and a carbon-containing gas is used. Existing technology

[0002] It is known to use reducing gases to reduce materials containing metal oxides, such as iron oxides, like ores. This can be achieved, for example, through direct reduction using reducing gases in reduction units, such as reduction shafts; and in blast furnace methods, where carbon monoxide (CO) serves as the reducing gas in the blast furnace. In conventional methods currently used on a large industrial scale, the reducing gas is primarily based on carbon-containing gases, such as natural gas or coke oven gas. This results in the generation of large quantities of carbon dioxide (CO2), which is particularly undesirable for environmental policy reasons.

[0003] To reduce CO2 emissions during the reduction of materials containing metal oxides, hydrogen (H2) is known to be used as a reducing gas. Here, hydrogen can be used as the sole reducing gas or in combination with other gases, such as natural gas-based reducing gases. The higher the proportion of CO2-neutral hydrogen (H2) in the reducing gas, the less CO2 is emitted.

[0004] However, due to its physical properties, storing hydrogen (H2) and transporting it from production sites to consumption sites is problematic and involves significant costs.

[0005] To reduce CO2 emissions during the reduction of materials containing metal oxides, ammonia (NH3) is also known to be used as a reducing agent. Ammonia has significant advantages over hydrogen (H2) in terms of storage and transportation.

[0006] Ammonia can be broken down into nitrogen and hydrogen. .

[0007] Hydrogen gas (H2) can act as a reducing agent in reactions with metal oxides, such as iron oxides. .

[0008] However, ammonia itself can also act as a reducing agent: .

[0009] In principle, materials containing metal oxides can also be reduced using a reducing gas obtained from ammonia (NH3); therefore, the reducing gas can be, for example, ammonia (NH3), or a mixture of ammonia (NH3) and one or more other gases (preferably one or more that can reduce materials containing metal oxides), as is the case, for example, with a mixture of ammonia and its cracking products (i.e., hydrogen (H2) and nitrogen (N2), wherein the mixture may of course also contain other gases. However, the reducing gas obtained from ammonia (NH3) can also be a reducing gas that does not contain ammonia (NH3) but contains hydrogen (H2) (alone or together with nitrogen (N2)) obtained from cracking, which is optionally mixed with one or more other gases (preferably one or more that can reduce materials containing metal oxides).

[0010] The reduction reaction that produces metallic iron (Fe) from hydrogen (H2) and ammonia (NH3), as well as the cracking of ammonia into nitrogen (N2) and hydrogen (H2), is endothermic. This leads to problems regarding the thermodynamic and kinetic conditions required to sustain the reduction on an industrial scale.

[0011] The balance between the goal of reducing CO2 emissions by increasing the use of ammonia (NH3) and the problems associated with ammonia utilization can be achieved through the combined use of ammonia and carbon-containing gases. Summary of the Invention

[0012] Technical Purpose The purpose of this invention is to provide the possibility of using ammonia and carbon-containing gases in combination during the reduction of materials containing metal oxides.

[0013] Technical solution The objective is achieved by reducing materials containing metal oxides. The reducing gas used is obtained by utilizing ammonia (NH3) and carbon-containing gases, and is introduced into the reduction unit. Its features are, In the process of producing reducing gases, a mixture containing ammonia and carbon-containing gases is prepared; and At least a portion of the mixture is first subjected to ammonia cracking conditions at a lower limit of 350°C, preferably 450°C, and an upper limit of 650°C, preferably 550°C, thereby producing a cracked gas mixture. Then, at least a portion of the pyrolysis gas mixture is subjected to reforming conditions at a temperature of 700°C to a lower limit and 1150°C to an upper limit, preferably 1000°C, to reform the carbon-containing gas. Furthermore, the reformed gas obtained after undergoing the reforming conditions contributes to the reducing gas.

[0014] The material containing metal oxides is preferably a material containing iron oxides.

[0015] The reduction method is, for example, the direct reduction method.

[0016] The reducing gas is obtained by utilizing ammonia (NH3), with ammonia contributing to the reducing gas. For example, the reducing gas is a mixture of ammonia (NH3) and one or more other gases. However, the reducing gas obtained by utilizing ammonia (NH3) can also be a reducing gas that does not contain ammonia (NH3) but contains hydrogen (H2) obtained from cracking (alone or together with nitrogen (N2)), which is mixed with one or more other gases.

[0017] Therefore, the reducing gas may contain ammonia; it is composed in part of ammonia and other components. Preferably, components that have a reducing effect on materials containing metal oxides are other components of the reducing gas; such components may be, for example, hydrocarbon-containing gases, carbon-containing gases, hydrogen-containing gases, or hydrogen. According to the invention, the reducing gas is obtained by utilizing ammonia, wherein the ammonia is cracked, and the resulting mixture of cracked gases containing nitrogen and hydrogen, and optionally ammonia—optionally enriched with hydrogen or depleted with nitrogen—contributes to the reducing gas. Ammonia contributes to the reducing gas; this contribution exists in addition to the contribution of carbon-containing gases to the reducing gas. Besides the components contributed by utilizing carbon-containing gases, ammonia provides other components of the reducing gas.

[0018] The cracking of ammonia (NH3) is carried out under ammonia cracking conditions within a temperature range having a lower and upper limit. The lower limit of this range can be 350°C, preferably 450°C. The upper limit of this range can be 650°C, preferably 550°C. A cracked gas mixture is produced here from a mixture containing ammonia and a carbon-containing gas, which contains nitrogen and hydrogen, and optionally ammonia. If not all the ammonia in the mixture reacts under ammonia cracking conditions, but only a portion of the ammonia in the mixture reacts, then the cracked gas mixture also contains ammonia. Unreacted residual ammonia in the mixture exists as ammonia in the cracked gas mixture. A maximum ammonia content of 10% by volume, preferably 8% by volume, and more preferably 6% by volume, in the cracked gas mixture is acceptable. To achieve the ammonia cracking conditions, a catalyst that catalyzes ammonia cracking within this temperature range is used.

[0019] In principle, ammonia of various "colors" is acceptable. "Color" here is understood to refer to a color associated with the type of production on which it is based. The color of ammonia is generally related to the color of the hydrogen used in its production. For example, ammonia can be green, if it is produced using green hydrogen; it can be blue, if it is produced using hydrogen obtained through the sequestration of carbon dioxide (CO2). Ammonia can also be produced using turquoise hydrogen, if it is produced by separating carbon (C); it can be produced using pink hydrogen, if it is produced using nuclear power. Mixtures of one or more of these "colors" of ammonia, or mixtures of the colors of the hydrogen on which ammonia is based, can also be considered.

[0020] The reducing gas is obtained by utilizing a carbon-containing gas. This carbon-containing gas can be a pure gas, such as pure methane, or it can be a mixture of various gases, such as natural gas or coke oven gas. The carbon in the carbon-containing gas can be, for example, hydrocarbons, such as methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H). 10 It may exist, for example, in the form of carbon monoxide (CO) or carbon dioxide (CO2). The carbon-containing gas used may be, for example, natural gas, or top gas discharged from the reduction unit—optionally after processing.

[0021] Carbon-containing gases contribute to the reducing gas; this contribution exists in addition to the contribution of ammonia to the reducing gas. Besides the components contributed by ammonia, carbon-containing gases provide other components of the reducing gas. These other components of the reducing gas are preferably components that have a reducing effect on materials containing metal oxides; they can be, for example, hydrocarbon-containing gases, carbon-containing gases, hydrogen-containing gases, and hydrogen gas.

[0022] According to the present invention, the utilization of carbon-containing gas is achieved at least by reforming the carbon-containing gas. At least a portion of the pyrolysis gas mixture is subjected to reforming conditions at a temperature ranging from a lower limit of 700°C to an upper limit of 1150°C, preferably 1000°C. To achieve the reforming conditions, a catalyst that catalyzes reforming within this temperature range—a so-called reforming catalyst—is used. Reforming conditions are understood to refer to the conditions under which the carbon-containing gas undergoes reforming. Reforming is understood to refer to the reforming of the carbon-containing gas. The reforming apparatus contains reforming conditions to make it suitable for the reforming of carbon-containing gas.

[0023] For example, reforming is carried out according to the following formula as steam reforming and / or CO2 reforming: .

[0024] The reforming process is illustrated using methane (CH4) as an example; for more advanced hydrocarbon compounds, the reforming process is similar.

[0025] According to the invention, in the process of producing reducing gas, a mixture comprising ammonia and a carbon-containing gas is prepared. This mixture can be prepared, for example, by combining ammonia with one or more carbon-containing gases; for example, by combining ammonia with a top gas (optionally after processing the top gas) and / or natural gas. If multiple carbon-containing gases are combined, they can be mixed together with ammonia, or, for example, a first carbon-containing gas can be mixed with ammonia first, and then a second carbon-containing gas can be added to the resulting mixture to obtain a mixture that serves as the basis for a cracked gas mixture. For example, the optionally processed top gas (as a carbon-containing gas) can be first mixed with ammonia, then natural gas is added, and then subjected to ammonia cracking.

[0026] First, a portion or all of the mixture is subjected to ammonia cracking conditions at a lower limit of 350°C, preferably 450°C, and an upper limit of 650°C, preferably 550°C, thereby producing a cracked gas mixture. Then at least a portion of the pyrolysis gas mixture is subjected to reforming conditions at a temperature of 700°C to 1150°C, preferably 1000°C.

[0027] For mixtures containing ammonia and carbon-containing gases, the term "partial quantity" refers to a portion of the volume of the resulting mixture.

[0028] For a cracked gas mixture, the utilization of a portion of the mixture can occur either when only a portion of the volume of the cracked gas mixture is utilized while the composition of the mixture remains unchanged, or when not all components of the cracked gas mixture are utilized—for example, when a component is enriched or depleted and the corresponding enriched or depleted gas stream is fully or partially utilized.

[0029] Before undergoing reforming conditions, other gases can be added to the pyrolysis gas mixture (or the portion thereof set for reforming conditions). For example, carbonaceous gases can be added; natural gas, for instance, can be added to the pyrolysis gas mixture. This carbonaceous gas will then also undergo the reforming reaction and contribute to the generation of reducing gases.

[0030] A reducing gas is a gas introduced into a reduction apparatus or its internal space containing a material containing a metal oxide (in which a reduction reaction occurs), having the composition and temperature present upon introduction. Prior to the presence of this composition and temperature, a reducing gas precursor on which the preparation of the reducing gas is based exists. This preparation can be achieved, for example, by adding other components or by heating. The preparation can also be achieved through a chemical reaction in the precursor without external intervention, such as altering the chemical composition or temperature.

[0031] Reduction units can be, for example, reduction shafts, such as fixed-bed reduction shafts containing materials containing metal oxides in direct reduction processes. Reduction units can also be, for example, fluidized-bed reactors, such as reduction units containing fluidized-bed reactors containing materials containing metal oxides in direct reduction processes. Fluidized-bed reactors can also comprise multiple independent sub-reactors, which are connected in parallel or series to form a fluidized-bed reactor. For example, a reduction unit can be a fluidized-bed reactor—such as a reduction unit containing fluidized-bed reactors containing materials containing metal oxides in direct reduction processes. Fluidized-bed reactors can also comprise multiple independent sub-reactors, which are connected in parallel or series to form a fluidized-bed reactor. A reduction unit can also be a blast furnace containing a fixed-bed reactor containing materials containing metal oxides—in which case ammonia can replace, for example, PCI coal or fossil reducing gases during blast furnace operation.

[0032] Advantages of the present invention Ammonia cracking is a strongly endothermic reaction (+93 kJ / mol). Therefore, ammonia cracking leads to a significant local temperature drop, which is undesirable in both reforming and reduction units. Consequently, the feed gas to the reforming unit and the reducing gas sent to the reduction shaft should not contain large amounts or concentrations of NH3.

[0033] Steam reforming and CO2 reforming and The reforming reaction of ammonia is carried out using a catalyst at temperatures of 700–1150 °C for kinetic and thermodynamic reasons. If the temperature during ammonia cracking is also within this range, it will lead to extremely rapid decomposition of ammonia, resulting in a rapid and significant local temperature drop. This temperature drop during the reforming process can have adverse effects, such as reduced natural gas conversion or carbon deposition. or ) .

[0034] To avoid this unfavorable interaction between ammonia cracking and reforming, the present invention performs ammonia cracking prior to reforming. The heat required to sustain endothermic ammonia cracking is provided before reforming. After ammonia cracking, the resulting cracked gas mixture undergoes reforming conditions at a temperature of 700–1150°C.

[0035] In a preferred embodiment, the mixture is heated before undergoing ammonia cracking conditions.

[0036] The advantage of preheating the mixture is that it establishes temperature conditions favorable for ammonia cracking. The energy provided during heating is already present in the mixture. The energy provided for heating can be provided, for example, through heat exchange with the waste gas produced during reforming. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit used to melt the reduction products, heat from the top gas, or steam generated from these heat sources can also be utilized.

[0037] In a preferred embodiment, depending on the flow direction of the mixture, the mixture first passes through an ammonia cracker, and then the resulting cracked gas mixture is optionally passed through a reforming unit under heating.

[0038] The advantage of heating the cracked gas mixture before introducing it into the reforming unit is that it allows for the establishment of temperature conditions favorable for reforming. The energy provided during heating is already present in the cracked gas mixture when it is introduced into the reforming unit and does not need to be provided in the reforming unit. The energy provided for heating can be provided, for example, through heat exchange with the waste gas produced during reforming. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit used to melt the reduction products, heat from the top gas, or steam generated from these heat sources can also be utilized.

[0039] In another preferred embodiment, the mixture passes through at least one pipe containing both a catalyst material for ammonia cracking and a catalyst material for reforming, wherein, depending on the flow direction of the mixture, the catalyst material for ammonia cracking is arranged upstream of the catalyst material for reforming.

[0040] In one embodiment, during the preparation of the mixture, the carbon-containing gas is heated, and then ammonia is added. Here, the ammonia may also have been preheated, for example, through heat exchange with the waste gas produced by reforming. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit used to melt the reduction products, heat from the top gas, or steam generated from these heat sources may also be utilized.

[0041] In another embodiment, ammonia is heated during the preparation of the mixture and then added to the carbon-containing gas. For example, the ammonia can be heated by heat exchange with the waste gas from the reforming process. Here, the carbon-containing gas may also have been preheated, for example, by heat exchange with the waste gas from the reforming process. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit used to melt the reduction products, heat from the top gas, or steam generated from these heat sources may also be utilized.

[0042] During the reduction of materials containing metal oxides, a top gas is generated, which can optionally be used, at least in part, for the production of reducing gases after processing. The processing includes, for example, dust removal, cooling, reducing and / or adjusting water vapor content, enriching or depleting certain components.

[0043] The top gas is discharged from the reduction unit. The top gas is formed by the reaction of the reducing gas as it flows through the reduction unit, due to the reaction of its components with materials containing metal oxides or products generated during the reaction (e.g., metallic iron). Because of the reduction reaction occurring in the reduction unit, the reducing power of the top gas is lower than that of the reducing gas. A portion or all of the top gas can—optionally after processing—be used as a component in the preparation of the reducing gas. Utilization of a portion exists both when only a fraction of the volume of the top gas produced is used while the composition of the top gas remains unchanged, and when not all components of the top gas are utilized—that is, for example, a certain component is enriched (e.g., hydrogen is enriched) and the corresponding enriched gas stream is utilized in whole or in part.

[0044] In a preferred embodiment, the treatment is carried out without reducing the carbon dioxide content.

[0045] In a preferred embodiment, the nitrogen content is reduced during the treatment process. For this purpose, for example, a device that separates nitrogen gas (N2) can be used.

[0046] If only a portion of the top gas is used to produce the reducing gas, the amount of nitrogen circulating into the reducing gas is reduced because, correspondingly, not all the nitrogen contained in the top gas enters the reducing gas. The top gas not used as a component in the preparation of the top gas can, for example, be used as a fuel component in the burner of a reforming unit.

[0047] In a preferred embodiment, energy is provided, at least in part, by electric heating to achieve the reforming conditions. Alternatively or additionally, waste heat from the reduction unit, or waste heat from the melting unit used to melt the reduction products, or heat from the top gas, or steam generated from these heat sources may also be utilized.

[0048] In a preferred embodiment, energy is provided, at least in part, by electric heating to achieve the ammonia cracking conditions. Alternatively or additionally, waste heat from the reduction unit, or waste heat from the melting unit used to melt the reduction products, or heat from the top gas, or steam generated from these heat sources may also be utilized.

[0049] In a preferred embodiment, heat extracted from the top gas is provided to the ammonia cracking process.

[0050] In a preferred embodiment, the ratio of ammonia to carbon-containing gas in the mixture can be varied. Hydrogen (H2) can also be added to the reducing gas precursor during the production of the reducing gas. In another preferred embodiment, the ratio of ammonia to hydrogen in the reducing gas can be varied. For example, the amount of hydrogen (H2) added can be increased or decreased, or the amount of ammonia can be increased or decreased.

[0051] To assist the endothermic ammonia cracking reaction—for example, in an optional ammonia cracker or in a pipeline containing both catalyst materials for ammonia cracking and catalyst materials for reforming—the heat generated during the reforming process can be utilized. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit for melting the reduction products, heat from the top gas, or steam generated by these heat sources can also be utilized. The heat generated during reforming is, for example, waste heat generated during reforming. The heat generated during reforming is understood, for example, as the production of hot exhaust gas during reforming, for example, through a combustion process that provides heat for carrying out reforming and is carried out by means of a burner; this hot exhaust gas—which contains waste heat generated during reforming—can be utilized so that its heat—i.e., waste heat generated during reforming—is used for ammonia cracking. For example, if the ammonia cracking unit is integrated into certain parts of the reforming unit, waste heat can be provided to the ammonia cracking unit via thermal radiation and / or convection.

[0052] To assist endothermic reforming reactions, the heat generated during the reforming process can be utilized, for example. This utilization can be achieved by heating the gas to be reformed, such as a pyrolysis gas mixture. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit used to melt the reduction products, heat from the top gas, or steam generated by these heat sources can also be utilized. The heat generated during reforming is, for example, waste heat generated during reforming. The heat generated during reforming is understood, for example, as the production of hot exhaust gas during reforming, for example, through a combustion process that provides heat for carrying out reforming and is carried out by means of a burner; this hot exhaust gas—which contains waste heat generated during reforming—can be utilized to make use of its heat—that is, the waste heat generated during reforming. Waste heat can be provided through thermal radiation and / or convection.

[0053] In one embodiment, the cracked gas mixture set for reforming conditions is heated before undergoing the reforming process. This prevents it from entering the reforming unit undercooled and thus avoiding carbon buildup. For this heating, waste heat from the reforming unit can be utilized, for example. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit used to melt the reduction products, heat from the top gas, or steam generated by these heat sources can also be utilized.

[0054] If heat is supplied via a burner during the reforming process, flue gas is generated. This flue gas, or the sealing gas obtained from it (an inert gas with a composition, for example, about 78% N2, 20% CO2, 1% O2, and 1% H2O), can contribute to heating to the temperature required for ammonia cracking (NH3). According to one embodiment, the heat supplied for ammonia cracking is at least partially provided by the flue gas.

[0055] The result of reforming conditions is the production of a so-called reformed gas. The reformed gas contributes to the reducing gas; the reformed gas can be a reducing gas or a reducing gas precursor.

[0056] In one approach, ammonia is added to the reformed gas. Ammonia contributes to the reducing capacity of the reformed gas in addition to the reducing components already present in it. However, preferably, the majority of the ammonia used to produce the reducing gas is used to generate the cracked gas mixture, with only a small fraction of the total ammonia amount added to the reformed gas. The reformed gas may also contain ammonia, as, as mentioned above, a cracked gas mixture may still contain ammonia. The ammonia content can be increased by adding ammonia to the reformed gas.

[0057] In one embodiment, ammonia is added to the reduction apparatus for reducing materials containing metal oxides, in addition to the introduction of a reducing gas; in another embodiment, the introduction of a reducing gas is independent. The ammonia, in addition to the reducing gas, can contribute to the reduction. However, preferably, the majority of the ammonia used is used to generate a cracked gas mixture, with only a small fraction of the total ammonia amount added to the reduction apparatus. The NH3 concentration in the reducing gas should not exceed 8% by volume, particularly preferably not more than 5% by volume.

[0058] In one embodiment, ammonia added to the reforming gas and / or reduction unit is heated. For this purpose, waste heat from the reforming process can be utilized, for example. Piping sections in heat exchangers can also be used to heat the top gas fuel by exchanging heat with the waste heat from the reforming unit. The top gas fuel is a portion of the top gas that is optionally used as a fuel component for burners operating in the reforming unit after processing. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from a melting device for melting reduction products, heat from the top gas, or steam generated from these heat sources can also be utilized.

[0059] Preferably, the ammonia content of the cracked gas mixture or the portion of the cracked gas mixture set for reforming—for example, in an NH3 absorber or a so-called NH3 stripper—is not reduced; in this respect, the feed of the cracked gas mixture for reforming is carried out directly.

[0060] Another subject of this invention is: Apparatus for reducing materials containing metal oxides It includes: - Reduction device, - The reducing gas input line into the reduction unit. - Carbon-containing gas supply pipelines, - Ammonia supply pipeline, Its features are, The carbon gas supply pipeline and the ammonia supply pipeline are connected to the mixture pipeline. The mixture pipeline is connected to the ammonia cracking unit. Furthermore, the cracked gas mixture pipeline extends from the ammonia cracking unit and enters the reforming unit to reform the carbon-containing gas. Furthermore, the reforming gas pipeline extends from the reforming unit and is connected to the reducing gas input pipeline.

[0061] The method of the present invention can be performed using this device.

[0062] Existing apparatuses for reducing materials containing metal oxides, including reforming devices, can be readily modified into the apparatus of the present invention, thereby enabling them to perform the methods of the present invention.

[0063] There may be one or more restoration devices.

[0064] There may be one or more reducing gas input lines.

[0065] There may be one or more carbon-containing gas supply pipelines.

[0066] There may be one or more ammonia supply lines.

[0067] There may be one mixture pipeline or multiple mixture pipelines.

[0068] There may be one or more ammonia cracking units.

[0069] There may be one or more pyrolysis gas mixture pipelines.

[0070] There may be one or more reforming units.

[0071] There may be one reforming gas pipeline or multiple reforming gas pipelines.

[0072] In the reduction apparatus, materials containing metal oxides are reduced using a reducing gas. The reducing gas is introduced into the reduction apparatus through a reducing gas inlet line.

[0073] A carbon-containing gas supply pipeline transports carbon-containing gas. According to one embodiment, the carbon-containing gas supply pipeline includes a heating device for heating the carbon-containing gas; for example, a heat exchanger, which is used, for example, to exchange heat with waste gas generated from reforming. Alternatively or additionally, a heating device may also be included that utilizes electrical energy, waste heat from the reduction unit, or waste heat from a melting unit used to melt the reduction products, heat from the top gas, or steam generated from these heat sources.

[0074] The ammonia supply line delivers ammonia—pure or in the form of an ammonia-containing gas mixture. According to one embodiment, the ammonia supply line includes a heating device for heating the ammonia; for example, a heat exchanger, which is used, for example, to exchange heat with the waste gas produced during reforming. Alternatively or additionally, a heating device may also be present, which utilizes electrical energy, waste heat from the reduction unit, or waste heat from a melting unit used to melt the reduction products, or heat from the top gas, or steam generated from these heat sources.

[0075] A carbon-containing gas supply line and an ammonia supply line are connected to a mixing line. This mixing line is used to transport a mixture of carbon-containing gas and ammonia. The mixing line may include a gas mixer area; in one embodiment, the carbon-containing gas supply line and the ammonia supply line are connected to a gas mixer area where they are mixed using a gas mixer, and the resulting mixture is further transported in the mixing line.

[0076] In one embodiment, the mixing pipeline contains a heating device for heating the mixture; for example, a heat exchanger, which is used, for example, to exchange heat with the waste gas produced by reforming. Alternatively or additionally, a heating device may also be present that utilizes electrical energy, waste heat from the reduction unit, or waste heat from a melting unit used to melt the reduction products, or heat from the top gas, or steam generated by these heat sources.

[0077] The mixture pipeline leads to the ammonia cracking unit—that is, the mixture is supplied to the ammonia cracking unit through this pipeline. Ammonia cracking conditions exist in the ammonia cracking unit at a lower limit of 350°C, preferably 450°C, and an upper limit of 650°C, preferably 550°C. At least a portion of the ammonia in the mixture is cracked in the ammonia cracking unit. The cracked gas mixture pipeline extends from the ammonia cracking unit.

[0078] In one embodiment, the cracked gas mixture pipeline includes a heating device for heating the cracked gas mixture; for example, a heat exchanger for exchanging heat with the waste gas produced from reforming. Alternatively or additionally, a heating device may also be present that utilizes electrical energy, waste heat from the reduction unit, or waste heat from a melting unit for melting reduction products, or heat from the top gas, or steam generated by these heat sources.

[0079] In one embodiment, there is no device for reducing ammonia content in the cracked gas mixture pipeline.

[0080] In one implementation, there is no device downstream of the ammonia cracking unit for reducing ammonia content in the gas flow direction toward the reduction unit.

[0081] In one embodiment, the ammonia cracking unit includes an electric heating device. The electric heating device uses electrical energy for heating. Alternatively or additionally, a heating device may also be present that utilizes waste heat from the reduction unit, or waste heat from the melting unit used to melt the reduction products, or heat from the top gas, or steam generated by these heat sources for heating.

[0082] In one embodiment, the ammonia cracking unit includes a heat exchanger for exchanging heat with the flue gas produced by the reforming unit. Flue gas is generated when heating is provided in the reforming unit using a burner. This flue gas is discharged from the reforming unit via a flue gas discharge line. The heat of the flue gas can be utilized by passing the flue gas discharge line through the heat exchanger of the ammonia cracking unit during the ammonia cracking process. In one embodiment, hot flue gas can be passed through the ammonia cracking unit; for example, if a mixture flows through pipes containing a catalyst in the ammonia cracking unit, the flue gas can be surrounded by these pipes for heat transfer. Waste heat from the reduction unit, or waste heat from the melting unit used to melt the reduction products, or heat from the top gas can also be used to supply heat to the ammonia cracking unit. Alternatively or additionally, electrical energy, waste heat from the reduction unit, waste heat from the melting unit used to melt the reduction products, heat from the top gas, or steam generated from these heat sources can also be utilized.

[0083] A cracked gas mixture pipeline leads to the reforming unit—the cracked gas mixture generated in the ammonia cracking unit is thus supplied to the reforming unit via this pipeline. Reforming conditions exist in the reforming unit at a lower limit of 700°C and an upper limit of 1150°C, preferably 1000°C. At least a portion of the carbon-containing gas in the cracked gas mixture undergoes reforming in the reforming unit. Reformed gas is obtained in the reforming unit. The reformed gas pipeline extends from the reforming unit.

[0084] In one embodiment, the reforming unit includes an electric heating device. Alternatively or additionally, a heating device may also be present, which utilizes waste heat from the reduction unit, or waste heat from the melting unit used to melt the reduction products, or heat from the top gas, or steam generated by these heat sources for heating.

[0085] In one embodiment, the ammonia cracking unit is designed as an ammonia cracker; the ammonia cracker is a separate unit from the reforming unit. In another embodiment, the ammonia cracking unit is designed to be integrated into certain parts of the reforming unit. For example, the reforming unit is a reformer comprising multiple pipes containing catalyst materials for reforming. By having the pipes of the reformer filled with both catalyst materials for ammonia cracking and catalyst materials for reforming, the ammonia cracking unit can, for example, be integrated into certain parts of the reforming unit, wherein, viewed according to the flow direction of the mixture, the catalyst materials for ammonia cracking are located upstream of the catalyst materials for reforming.

[0086] In one embodiment, the apparatus for reducing a material containing metal oxides includes a top gas exhaust line for discharging top gas from the reduction apparatus. In a preferred embodiment, the top gas exhaust line connects to a carbon-containing gas supply line. In one embodiment, the top gas exhaust line includes at least one processing device. The processing device performs actions such as dust removal, cooling, reducing and / or regulating water vapor content, enriching or depleting certain components.

[0087] Preferably, the top gas exhaust line does not contain any device for reducing carbon dioxide content. Preferably, the top gas exhaust line includes at least one device for separating nitrogen (N2). Preferably, at least one fuel line extends from the top gas exhaust line for supplying the top gas as a fuel component for the burner of the reforming unit.

[0088] In a preferred embodiment, the apparatus for reducing a material containing metal oxides includes means for controlling and / or adjusting the ratio of ammonia to carbon-containing gas in the mixture. This apparatus includes sensors for determining the content of ammonia and carbon-containing gas in the mixture.

[0089] In a preferred embodiment, the apparatus for reducing a material containing metal oxides includes means for controlling and / or adjusting the ratio of ammonia to hydrogen in the reducing gas. This apparatus includes sensors for measuring the ammonia and hydrogen content in the reducing gas.

[0090] In a preferred embodiment, the apparatus for reducing a material containing a metal oxide includes at least one hydrogen addition line for adding hydrogen (H2) to a reforming gas line. The hydrogen addition line is connected to the reforming gas line.

[0091] In a preferred embodiment, the apparatus for reducing a material containing metal oxides includes at least one ammonia addition line for adding ammonia to a reforming gas line. The ammonia addition line is connected to the reforming gas line.

[0092] In a preferred embodiment, the apparatus for reducing a material containing metal oxides includes at least one ammonia feed line for adding ammonia to the reduction apparatus—in addition to the introduction of a reducing gas or in addition to a reducing gas inlet line; the addition of ammonia to the reduction apparatus can be carried out independently of the introduction of a reducing gas. The ammonia feed line leads into the reduction apparatus.

[0093] In one embodiment, the ammonia feed line includes a heating device for heating the ammonia; for example, a heat exchanger, which is used, for example, to exchange heat with the waste gas produced by reforming. To utilize the waste heat from reforming, sections of piping within the heat exchanger can be used, for example, to heat the top gas fuel by exchanging heat with the waste heat from the reformer. Alternatively or additionally, a heating device may be present that utilizes electrical energy, waste heat from the reduction unit, or waste heat from a melting unit for melting the reduction products, or the heat from the top gas, or steam generated from these heat sources.

[0094] Another subject of this application is a signal processing apparatus having machine-readable program code, characterized in that the apparatus includes control and / or regulation instructions for implementing the method of the present invention. Another subject is a signal processing apparatus for implementing the method according to any one of claims 1 to 8.

[0095] Another subject of this application is machine-readable program code for a signal processing apparatus, characterized in that the program code contains control and / or regulation instructions that cause the signal processing apparatus to implement the method of the present invention. Another subject is a computer program product containing instructions for a signal processing apparatus that, when the program of the signal processing apparatus is executed, cause the signal processing apparatus to implement the method according to any one of claims 1 to 8.

[0096] Another subject of this application is a storage medium storing machine-readable program code of the present invention. Another subject is a storage medium storing a computer program for implementing the method according to any one of claims 1 to 8. Brief description of the attached diagram The present invention is described below by way of several schematic diagrams.

[0098] Figure 1 The illustration schematically shows one embodiment of the method of the invention in one aspect of the apparatus for reducing materials containing metal oxides. Figure 2 Another option is shown schematically. Figure 3 Another solution was shown. Figure 4 Another option is shown schematically. Figure 5 Another option is illustrated schematically.

[0099] Implementation plan description. Example

[0100] Figure 1An apparatus 10 for reducing a metal oxide-containing material 20 is schematically shown. The metal oxide-containing material 20 is fed into a reduction unit 30. A reducing gas is introduced through a reducing gas inlet line 40 into the reduction unit 30 to reduce the metal oxide-containing material 20. The reducing gas is produced using ammonia (NH3) and a carbon-containing gas. For this purpose, a mixture containing ammonia and a carbon-containing gas is prepared. For this purpose, a carbon-containing gas supply line 50 and an ammonia supply line 60 are connected to a mixture line 70. The mixture line 70 is connected to an ammonia cracking unit 80. In the ammonia cracking unit 80, at least a portion of the mixture is subjected to ammonia cracking conditions at a lower limit of 350°C, preferably 450°C, and an upper limit of 650°C, preferably 550°C. This produces a cracked gas mixture. A cracked gas mixture line 90 extends from the ammonia cracking unit and is connected to a reforming unit 100. At least a portion of the pyrolysis gas mixture undergoes reforming conditions in reforming unit 100 at a lower limit of 700°C and an upper limit of 1150°C, preferably 1000°C. The resulting reformed gas is introduced into reducing gas input line 40 via reformed gas line 110 extending from reforming unit 100. Reformed gas line 110 leads into reducing gas input line 40.

[0101] A heating device for heating the carbon-containing gas may be present in the carbon-containing gas supply line 50, but for clarity, it is not shown separately.

[0102] Ammonia supply line 60 delivers ammonia. In one embodiment, a heating device for heating the ammonia is present in the ammonia supply line, but this is not shown separately for clarity.

[0103] Carbon gas supply line 50 and ammonia supply line 60 lead into mixing line 70. Mixing line 70 may include a gas mixer area; however, this is not shown separately for clarity. Mixing line 70 leads into ammonia cracking unit 80—the mixture is thus supplied to ammonia cracking unit 80 via mixing line 70. At least a portion of the ammonia in the mixture is cracked in ammonia cracking unit 80. Cracked gas mixture line 90 extends from ammonia cracking unit 80.

[0104] The ammonia cracking unit 80 may include an electric heating device 81; the optional electric heating device 81 is schematically represented by a lightning bolt symbol.

[0105] Optionally, alternatively, or additionally, a heating device may be present, which utilizes waste heat from the reduction unit, or waste heat from the melting unit used to melt the reduction products, or heat from the top gas, or steam generated from these heat sources for heating, but this is not shown separately for clarity. Optionally, the ammonia cracking unit may also additionally or alternatively include a heat exchanger for exchanging heat with the flue gas produced by the reforming unit, but this is not shown separately for clarity.

[0106] Optionally, a heating device for heating the mixture may be present in the mixture line 70; Figure 1 The device is shown as an optional heat exchanger 120, which is surrounded by a dashed line, for exchanging heat with the waste gas 130 (indicated by a serrated arrow) generated during reforming.

[0107] Optionally, a heating device for heating the pyrolysis gas mixture may be present in the pyrolysis gas mixture pipeline 90; Figure 1 The device is indicated as an optional heat exchanger 120, surrounded by a dashed line, for exchanging heat with the reformed exhaust gas 130 (indicated by a zigzag arrow). There is no device for reducing ammonia content in the cracked gas mixture line 90.

[0108] In the apparatus 10 for reducing the metal oxide-containing material 20, there is no apparatus for reducing the ammonia content downstream of the ammonia cracking unit 80 in the gas flow direction toward the reduction unit 30.

[0109] The reforming unit 100 may include an electric heating device 101; the optional electric heating device 101 is schematically represented by a lightning bolt symbol. Alternatively or additionally, a heating device may be present that utilizes waste heat from the reduction unit, or waste heat from a melting unit used to melt the reduction products, or heat from the top gas, or steam generated by these heat sources, but this is not shown separately for clarity. Figure 1 In this unit, the ammonia cracking unit 80 is designed as an ammonia cracker unit separate from the reforming unit 100.

[0110] Figure 2 Showing with Figure 1 A substantially identical embodiment, differing only in the design of the ammonia cracking unit 80. The ammonia cracking unit 80 is schematically shown as being designed to be integrated into certain portions of the reforming unit 100. The reforming unit 100 is a reformer comprising multiple pipes containing catalyst materials for reforming; pipe 91 is shown. The upper region 92 of pipe 91 contains the catalyst material for reforming, and the lower region 93 of the pipe contains the catalyst material for ammonia cracking. Viewed in the direction of mixture flow toward the reduction unit 30, the catalyst material for ammonia cracking is located upstream of the catalyst material for reforming.

[0111] Figure 3 Showing with Figure 1A substantially identical embodiment is shown, with the addition of a top gas discharge line 140 for discharging top gas from the reduction unit 30. The top gas discharge line 140 leads to a carbon-containing gas supply line 50. An optional (hence indicated by dashed lines) processing unit 150, in this example a dust removal unit, is also shown. The top gas discharge line 140 does not include any device for reducing carbon dioxide content. The top gas discharge line 140 may include a device for separating nitrogen (N2), but this is not shown separately for clarity. A fuel line may extend from the top gas discharge line to supply the top gas as fuel for the burners of the reforming unit 100, but this is not shown separately for clarity.

[0112] Figure 4 Showing with Figure 1 The embodiments are essentially the same. We will now only discuss the additional features shown: The apparatus 10 for reducing the metal oxide-containing material 20 also includes a device 160 for controlling and / or adjusting the ratio of ammonia to carbon-containing gas in the mixture. A sensor 170 for determining the ammonia and carbon-containing gas content in the mixture is also shown. The apparatus 10 for reducing material 20 containing metal oxides further includes a device 180 for controlling and / or adjusting the ratio of ammonia to hydrogen in the reducing gas. A sensor 190 for determining the ammonia and hydrogen content in the reducing gas is also shown. The apparatus 10 for reducing the metal oxide-containing material 20 also includes a hydrogen addition line 200 for adding hydrogen (H2) to the reforming gas line 110. The hydrogen addition line 200 is connected to the reforming gas line 110. The apparatus 10 for reducing the metal oxide-containing material 20 also includes an ammonia addition line 210 for adding ammonia to the reforming gas line 110. The ammonia addition line 210 is connected to the reforming gas line 110. - The apparatus 10 for reducing the metal oxide-containing material 20 also includes an ammonia feed line 220 for adding ammonia to the reduction apparatus 30. In addition to the reducing gas input line 40, the ammonia feed line 220 also leads to the reduction apparatus 30; ammonia is added to the reduction apparatus 30 independently of the introduction of reducing gas into the reduction apparatus 30.

[0113] A heating device for heating ammonia may be present in the ammonia feed line 220; for example, a heat exchanger, which is used for heat exchange with the waste gas generated from reforming. Here, to utilize the waste heat generated from reforming, pipeline sections in the heat exchanger may be used, for example, to heat the top gas fuel by heat exchange with the waste heat from the reformer. Waste heat from the reduction unit, or waste heat from the melting unit for melting the reduction products, or heat from the top gas may also be utilized. However, this is not shown separately for clarity. Alternatively or additionally, a heating device may be present that utilizes electrical energy, waste heat from the reduction unit, or waste heat from the melting unit for melting the reduction products, or heat from the top gas, or steam generated from these heat sources. However, this is not shown separately for clarity.

[0114] Figure 5 based on Figure 1 The diagram schematically illustrates how flue gas 130 discharged from reforming unit 100 via a flue gas exhaust line can be used for the ammonia cracking process in ammonia cracking unit 230. Hot flue gas is guided through a catalyst-containing conduit 240 within the ammonia cracking unit 230, through which the mixture flows. The flue gas 230 surrounds these conduits for heat transfer.

[0115] List of reference numerals 10. Apparatus for reduction 20 Materials containing metal oxides 30 Reduction Device 40 Reducing gas input line 50 Carbon-containing gas supply pipelines 60 Ammonia Supply Pipeline 70 Mixture Piping 80 Ammonia Cracking Unit 81 Electric heating device 90 Pyrolysis gas mixture pipeline 91 Pipeline 92 Upper Area 93 Lower area 100 Reforming Unit 101 Electric heating device 110 Reformer Gas Pipeline 120 heat exchanger 130 Waste gas generated from reforming 140 Top Gas Exhaust Line 150 processing unit 160 Device for controlling and / or adjusting the ratio of ammonia and carbonaceous gas in a mixture. 170 sensor 180 Device for controlling and / or adjusting the ratio of ammonia and hydrogen in a reducing gas. 190 sensor 200 Hydrogen Refill Line 210 Ammonia Addition Pipeline 220 Ammonia Feed Pipeline 230 Ammonia Cracking Unit 240 pipes.

Claims

1. A method for reducing a material containing metal oxides, wherein a reducing gas obtained by utilizing ammonia (NH3) and a carbon-containing gas is introduced into a reduction apparatus. Its features In the process of producing reducing gases, a mixture containing ammonia and carbon-containing gases is prepared; and At least a portion of the mixture is first subjected to ammonia cracking conditions at a lower limit of 350°C, preferably 450°C, and an upper limit of 650°C, preferably 550°C, thereby producing a cracked gas mixture. Then, at least a portion of the pyrolysis gas mixture is subjected to reforming conditions at a temperature of 700°C to a lower limit and 1150°C to an upper limit, preferably 1000°C, to reform the carbon-containing gas. Furthermore, the reformed gas obtained after undergoing the reforming conditions contributes to the reducing gas.

2. The method according to claim 1, characterized in that, Based on the flow direction of the mixture, it first passes through an ammonia cracker, and then the resulting cracked gas mixture passes through a reforming unit (100).

3. The method according to claim 1, characterized in that, The mixture passes through at least one pipe containing both a catalyst material for ammonia cracking and a catalyst material for reforming, wherein, according to the flow direction of the mixture, the catalyst material for ammonia cracking is arranged upstream of the catalyst material for reforming.

4. The method according to any one of claims 1 to 3, wherein a portion or all of the top gas is used as a component in the preparation of the reducing gas after treatment, characterized in that, The treatment is carried out without reducing the carbon dioxide content.

5. The method according to any one of claims 1 to 4, wherein a portion or all of the top gas is used as a component in the preparation of the reducing gas after treatment, characterized in that, The nitrogen content is reduced during the treatment process.

6. The method according to any one of claims 1 to 5, characterized in that, The heat generated during the reforming process is used to assist the endothermic ammonia cracking reaction.

7. The method according to any one of claims 1 to 6, wherein the reduction of the metal oxide-containing material is carried out in a reduction apparatus (30), characterized in that, In addition to introducing reducing gas, ammonia is also added to the reduction device (30).

8. The method according to any one of claims 1 to 7, characterized in that, For the pyrolysis gas mixture or the portion of the pyrolysis gas mixture set for reforming, no ammonia content reduction is performed.

9. An apparatus (10) for reducing a material (20) containing a metal oxide, It includes: - Reduction device (30), - The reducing gas input line (40) into the reduction device (30), - Carbon-containing gas supply pipeline (50), - Ammonia supply pipeline (60), Its features are, The carbon gas supply line (50) and the ammonia supply line (60) are connected to the mixture line (70). And the mixture pipeline (70) is connected to the ammonia cracking unit (80), Furthermore, a cracked gas mixture pipeline (90) extends from the ammonia cracking unit (80), and this cracked gas mixture pipeline (90) leads into the reforming unit (100) to reform the carbon-containing gas. Furthermore, the reforming gas line (110) extends from the reforming unit (100) and is connected to the reducing gas input line (40).

10. The apparatus according to claim 9, characterized in that, The ammonia cracking unit (80) includes a heat exchanger (120) for exchanging heat with flue gas from the reforming unit (100).

11. The apparatus according to claim 9 or 10, characterized in that, The ammonia cracking unit (80) is designed as an ammonia cracker.

12. The apparatus according to claim 9 or 10, characterized in that, The ammonia cracking unit (80) is designed to be integrated into certain parts of the reforming unit (100).

13. The apparatus according to any one of claims 9 to 12, comprising a top gas discharge line (140) for discharging top gas from the reduction apparatus (30), characterized in that, The top gas exhaust line (140) does not include any device for reducing carbon dioxide levels.

14. The apparatus according to any one of claims 9 to 13, comprising a top gas discharge line (140) for discharging top gas from the reduction apparatus (30), characterized in that, The top gas discharge line (140) includes at least one device for separating nitrogen (N2).

15. The apparatus according to any one of claims 9 to 14, characterized in that, It includes at least one ammonia feed line (220) for adding ammonia to the reduction unit (30).

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