Reduction of a metal oxide-containing material on the basis of ammonia nh3
Patent Information
- Application Number
- EP2023716441
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-07
- Filing Date
- 2023-03-29
- Publication Date
- 2025-02-05
AI Technical Summary
The industrial reduction of metal oxide-containing materials using ammonia as a reducing agent faces challenges in energy efficiency and nitrogen utilization, as well as the environmental impact of CO2 emissions from conventional reducing gases.
A process that recycles top gas from the reduction reactor to prepare the reducing gas, utilizing ammonia and its cleavage products, while controlling nitrogen content and incorporating additional components to enhance energy efficiency and reduce CO2 emissions.
This approach conserves energy, reduces nitrogen accumulation, and minimizes CO2 emissions by utilizing the residual reducing power and heat content of the top gas, making the process more resource-efficient and environmentally friendly.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Reduction of metal oxide-containing material based on ammonia NH3
[0003] field of technology
[0004] The application relates to a method and device for the reduction of material containing metal oxide, using reducing gas obtained by utilising ammonia NH3.
[0005] State of the art
[0006] It is known that materials containing metal oxides, such as iron oxide, such as ores, can be reduced using reducing gas. For example, direct reduction with reducing gas in a reduction unit, such as a reduction shaft; in blast furnace processes, carbon monoxide (CO), for example, also acts as a reducing gas in the blast furnace reduction unit. In conventional processes currently used on a large industrial scale, the reducing gas is predominantly based on natural gas. Therefore, large quantities of carbon dioxide (CO2) are produced, which is undesirable for environmental reasons, among other things.
[0007] To reduce CO2 emissions during the reduction of metal oxide-containing materials, it is known to use hydrogen H2 as a reducing gas. Hydrogen can be used as the sole reducing gas or in combination with other gases, such as natural gas-based reducing gases. The greater the proportion of CO2-neutral hydrogen H2 in the reducing gas, the less CO2 is emitted.
[0008] However, storage of hydrogen H2 and transport from the place of its production to consumers is problematic due to its physical properties and involves great
[0009] effort involved.
[0010] To reduce CCt emissions during the reduction of metal oxide-containing materials, it is also known to use ammonia NH3 as a reducing agent. Ammonia offers significant advantages over hydrogen H2 with regard to storage and transport.
[0011] Ammonia can be split into nitrogen and hydrogen
[0012] 2 NH3 -> N2 + 3 H2.
[0013] Hydrogen H2 can react as a reducing agent with metal oxides, for example iron oxides:
[0014] Ammonia can also act as a reducing agent itself:
[0015] In principle, reducing gas obtained using ammonia NH3 can be used to reduce material containing metal oxides; such a reducing gas can be, for example, ammonia NH3, or a mixture of ammonia NH3 with one or more other gases - whereby one or more can preferably have a reducing effect on material containing metal oxides, which would be the case, for example, with a mixture of ammonia and its decomposition products hydrogen H2 and nitrogen N2, although other gases could of course also be included in the mixture.However, the reducing gas obtained using ammonia NH3 can also be a reducing gas which does not contain ammonia NH3 but contains the fission product hydrogen H2 obtained from a fission - alone or together with the fission product nitrogen N2 -, optionally in a mixture with one or more other gases - whereby preferably one or more can have a reducing effect on metal oxide-containing material.
[0016] Such reduction reactions for the production of metallic iron (Fe) with hydrogen (H2) and ammonia (NH3), as well as the splitting of ammonia into nitrogen (N2) and hydrogen (H2), are endothermic. Accordingly, the problem arises as to how sufficient energy can be supplied in a resource-efficient manner for such reactions to occur on an industrial scale.
[0017] During the splitting of ammonia and its action as a reducing agent, significant amounts of nitrogen N2 are produced in addition to hydrogen H2. Accordingly, the problem arises as to how the resulting nitrogen can be utilized to benefit the process in industrial applications.
[0018] Summary of the invention
[0019] Technical task
[0020] It is the object of the present invention to provide a contribution to solving at least some of the aforementioned problems.
[0021] Technical solution
[0022] The task is solved by a
[0023] Process for the reduction of metal oxide-containing material, wherein reducing gas obtained using ammonia NH3 is used, wherein the reducing gas is fed to a reduction reactor containing the metal oxide-containing material, and a top gas is discharged from the reduction reactor, characterized in that at least a portion of the top gas, optionally after processing of the top gas, is used as a component in the preparation of the reducing gas.
[0024] The metal oxide-containing material is preferably iron oxide-containing material.
[0025] The reduction process is, for example, a direct reduction process.
[0026] The reducing gas is obtained using ammonia NH3.
[0027] Such a reducing gas can, for example, be ammonia NH3, or a mixture of ammonia NH3 with one or more other gases - where preferably one or more can have a reducing effect on material containing metal oxide - which would be the case, for example, with a mixture of ammonia and its fission products hydrogen H2 and nitrogen N2, although of course other gases could also be present in the mixture. The reducing gas obtained using ammonia NH3 can, however, also be a reducing gas which does not contain any ammonia NH3, but contains the fission product hydrogen H2 obtained from a fission - alone or together with the fission product nitrogen N2 - optionally in a mixture with one or more other gases - where preferably one or more can have a reducing effect on material containing metal oxide.
[0028] The reducing gas can therefore comprise ammonia; it can consist partly or completely of ammonia. If it consists only partly of ammonia, it contains other components; one aspect of the use of the ammonia is then its mixing with the other components; for example, ammonia can be added to the other components in such a way that it makes up more than 0.5 full of the gas stream obtained after its addition. Possible other components can be those which are inert with regard to reactions with the metal oxide-containing material under the conditions prevailing in the reduction reactor - for example nitrogen N2 - as well as those which react with the metal oxide-containing material under the conditions prevailing in the reduction reactor.In this regard, components which have a reducing effect on the metal oxide-containing material are preferred; these may, for example, be hydrocarbon-containing gases, carbon-containing gases, hydrogen-containing gases, or hydrogen.
[0029] Reducing gas can also be obtained using ammonia by splitting ammonia and mixing the resulting gas mixture of nitrogen and hydrogen - optionally after enrichment or depletion of nitrogen or hydrogen - with other components of the reducing gas.
[0030] Reducing gas can also be obtained using ammonia by splitting ammonia and separating the resulting hydrogen from the nitrogen and mixing it with other components of the reducing gas, or by using the entire reducing gas - possibly with any remaining small amounts of nitrogen produced during the splitting.
[0031] In principle, ammonia of any color is possible. "Color" therefore refers to the coloring in connection with the underlying production method. The color of the ammonia is often linked to the color of the hydrogen used in production. The ammonia can be green, for example, if it was produced using green hydrogen; it can be blue, for example, if it was produced using hydrogen obtained by sequestering carbon dioxide CO2. The ammonia can also be produced using turquoise hydrogen, for example, if the hydrogen is produced by separating out the resulting carbon C; it can be produced using pink hydrogen, for example, if the hydrogen is produced using nuclear power.A mixture of one or more of these “colours” of ammonia, or a mixture of colours of the hydrogen underlying ammonia, is also possible.
[0032] The reducing gas is the gas introduced into the reduction reactor, or rather its interior chamber containing metal oxide material where the reduction reactions take place, with its composition and temperature at the time of introduction. Before this composition and temperature are reached, a precursor of the reducing gas is present, on the basis of which the reducing gas is prepared. Preparation can take place, for example, by adding further components or heating. Preparation can also take place through chemical reactions taking place in the precursor without external intervention, which, for example, change the chemical composition or the temperature.
[0033] The reduction reactor is, for example, a reduction shaft—for example, when conducting a direct reduction process with a reduction shaft containing a fixed bed of metal oxide-containing material. The reduction reactor is, for example, a fluidized-bed reactor—for example, when conducting a direct reduction process with a reduction reactor containing a fluidized bed of metal oxide-containing material. The fluidized-bed reactor can also comprise several individual sub-reactors, which are connected, for example, in parallel or sequentially and together form the fluidized-bed reactor.
[0034] The reduction reactor is, for example, a fluidized-bed reactor—for example, when conducting a direct reduction process with a reduction reactor containing a fluidized bed of metal oxide-containing material. The fluidized-bed reactor can also comprise several individual sub-reactors, which are connected in parallel or sequentially, for example, and together form the fluidized-bed reactor.
[0035] The reduction reactor can also be a blast furnace containing a fixed bed of metal oxide-containing material - in the operation of a blast furnace, for example, ammonia can replace PCI coal or fossil reducing gases.
[0036] A top gas is discharged from the reduction reactor. The top gas is formed from the reducing gas as it flows through the reduction reactor due to the reactions taking place in the reduction reactor between its components and the metal oxide-containing material or the products formed during these reactions, for example, the resulting metallic iron. Due to the reduction reactions taking place in the reduction reactor, the top gas has less reducing power than the reducing gas.
[0037] At least a portion of the top gas is used—possibly after processing—as a component in the preparation of the reducing gas. A portion is used both when, with the composition of the top gas unchanged, only a portion of the resulting top gas volume is used, and when not all components of the resulting top gas are used—for example, when an enrichment of a component—e.g., hydrogen enrichment—occurs and the correspondingly enriched gas stream is fully or partially utilized.
[0038] One step in the preparation of the reducing gas is therefore - if no processing takes place - the mixing of top gas with other components of the reducing gas; either the gas mixture obtained in this way forms the reducing gas, or the reducing gas is prepared on the basis of this gas mixture, with further steps taking place, such as the addition of additional components or heating to the temperature desired for introduction into the reduction reactor, or chemical reactions leading to a change in the composition.
[0039] If necessary, the top gas is subjected to treatment.
[0040] The processing may involve one or more stages. Possible stages include:
[0041] - Dust removal - which can be carried out dry or wet,
[0042] - Cooling,
[0043] - Adjustment of the water vapor content to a desired level, if necessary by means of cooling,
[0044] - compaction,
[0045] - heating,
[0046] - Desulfurization; for example, in the reduction of sulfur-containing material, especially when reformers are used in the preparation of reducing gas.
[0047] Dust removal is preferably carried out dry, as the heat content of the gas can then be utilized more effectively in the process than with wet dust removal. For example, the heat can be used to evaporate the ammonia. The heat can also be used elsewhere in the process—if necessary via a heat transfer medium—for example, to generate hot water and / or steam.
[0048] Adjusting the water vapor content to a desired level is advantageous, for example, when natural gas is reformed with water vapor in a reformer during the preparation of reducing gas. Adjusting the water vapor content to a desired level is also advantageous because it affects the reducing gas quality - expressed as the ratio of the volume percent contents of carbon monoxide CO, hydrogen H2, carbon dioxide CO2, water H2O (CO+H2) / (CO2+H2O) or of hydrogen H2 and water H2O H2 / H2O.
[0049] The gas obtained after the processing step(s) is referred to as processing gas in the context of the present application.
[0050] When top gas is processed, the processing gas is used as a component in the preparation of the reducing gas - top gas is then used indirectly in the preparation of the reducing gas via the processing gas obtained from the top gas. One step in the preparation of the reducing gas is then the mixing of the processing gas with other components of the reducing gas; either the gas mixture obtained in this way forms the reducing gas, or the reducing gas is prepared on the basis of this gas mixture, with further steps taking place, such as the addition of additional components or heating to the desired temperature upon introduction into the reduction reactor, or chemical reactions leading to a change in the composition.
[0051] Advantageous effects of the invention
[0052] Although the top gas has less reducing power than the reducing gas due to the reduction reactions that took place in the reduction reactor, it still contains reducing components—such as hydrogen H2—and its reducing power is not yet exhausted. Furthermore, it has an energy content due to its temperature.
[0053] It is advantageous to utilize the reducing power still present in the top gas for the reduction process. It is also advantageous to utilize the energy content for the reduction process; with increasing utilization, the additional energy requirement for heating steps, which are used to adjust the required temperature of the reducing gas, decreases.
[0054] Especially in the case of endothermic reactions taking place in the reduction reactor, the supply of energy to the reduction reactor is important for maintaining the reactions. The energy can be supplied via the reducing gas and can be varied, for example, via the supplied quantity and temperature of the reducing gas. In the direct reduction of iron oxides, it is preferred if the reducing gas has a temperature above 750 ° C, particularly preferably above 800 ° C. When using a reducing gas that reduces only on the basis of hydrogen H2 and / or ammonia NH3, it is preferred in the direct reduction of iron oxides, for example, if the specific quantity of reducing gas introduced into the reduction reactor is above 2000 Nm 3 / ton of direct reduced iron DRI, preferably over 2200 Nm 3 / tDRI. If a reducing gas is used that also contains natural gas-based reducing components, a lower value is preferred, for example 1500 - 1600 Nm tDRI.
[0055] The use of the top gas - directly as top gas and / or indirectly via processing gas obtained on the basis of the top gas - for the preparation of the reducing gas enables the use of the reduction potential remaining in the top gas and the use of the heat content of the top gas.
[0056] The nitrogen contained in the top gas can be used as a heat transfer medium in the process. Even though the nitrogen is inert with regard to the reduction reactions, it therefore contributes to the resource-efficient implementation of the process. Energy that is carried into the reduction reactor by nitrogen via its heat content does not have to be introduced into the reduction reactor by other substances; for example, not by the components of the reduction gas that have a reduction potential. These components - for example ammonia NH3, hydrogen H2, hydrocarbons - are more expensive and more difficult to provide than the nitrogen N2 that is produced anyway when ammonia NH3 is split - one volume part of nitrogen N2 for every three volume parts of hydrogen H2 - and should therefore not necessarily be used in excess of stoichiometric amounts.These components should be used primarily for the purpose of reduction; their use without a significant contribution to the reaction turnover merely for the input of heat content is less resource-efficient and expensive compared to the use of nitrogen.
[0057] According to one embodiment, the treatment of the top gas withdrawn from the reduction reactor comprises a process step for reducing the nitrogen content.
[0058] The top gas undergoes a treatment process that includes at least a reduction of its nitrogen content. The nitrogen is not completely separated. This reduction is done to slow the enrichment of nitrogen in the reducing gas that occurs due to the use of the top gas and the associated reduction in the reducing power of the reducing gas.
[0059] To reduce the nitrogen content, processes using different permeation rates, processes using different adsorption forces, and processes using different boiling temperatures for the sorted liquefaction of the individual fractions are possible. Combinations of several of these processes are also possible.
[0060] These include processes such as membrane separation, for example with hollow fiber membranes or with separation membranes based on porous graphene or with single- or multi-stage inorganic membranes, processes such as pressure swing adsorption (PSA), and processes such as cryogenic distillation. The resulting gas stream with an increased nitrogen content can be utilized, for example thermally in a reducing gas furnace or in a reformer. The resulting gas stream with an increased content of reducing components - for example, an increased hydrogen content - due to the separation of the inert nitrogen is used in the preparation of the reducing gas.
[0061] Advantageously, the reduction of the nitrogen content is controlled in such a way that the reducing gas contains less than 40 vol%, preferably less than 30 vol%, particularly preferably less than 20 vol% nitrogen.
[0062] Although the amount of nitrogen contained in the top gas is reduced during top gas processing, the processing gas still contains residual nitrogen. Thus, the heat content of this nitrogen is utilized in the process. Even though this nitrogen is inert with respect to the reduction reactions, it contributes to the resource-efficient implementation of the process.
[0063] The nitrogen content in the reducing gas can also be controlled and / or regulated to a desired value by appropriately controlling and / or regulating the portion of the top gas—if necessary after processing the top gas—that is not used as a component in the preparation of the reducing gas. This portion is discharged from the reduction gas preparation cycle; the discharged discharge gas can be used thermally, for example, in a gas furnace, reducing gas furnace, or reformer. It is preferred if the discharge gas is discharged after cooling the top gas.
[0064] According to one embodiment, at least one member of the first group consisting of:
[0065] Ammonia; can be used in liquid or gaseous form. Hydrogen obtained from ammonia, for example as pure hydrogen or in a mixture of nitrogen N2 and hydrogen H2, is added.
[0066] One or more members of the first group can be added to the top gas and / or the processing gas.
[0067] Ammonia is preferably added in gaseous form. The ammonia can be heated prior to addition, for example, electrically. Heating can be achieved, for example, using a gas furnace, which can be heated with electrical energy, or by combustion of fuels. The first group comprises hydrogen obtained from ammonia; it is therefore ammonia-based hydrogen. This includes the hydrogen being added as a component of a gas mixture—for example, a gas mixture of nitrogen and hydrogen resulting from the splitting of ammonia.
[0068] According to one embodiment, at least one member of the second group consisting of:
[0069] - Natural gas
[0070] - Hydrocarbons, for example ethane C2H6, propane CaHs, butane C4H10,
[0071] - hydrogen,
[0072] - Carbon monoxide,
[0073] - Coke oven gas
[0074] - Syngas comprising several components from the group of components consisting of
[0075] CO, H2, CH4, C2-C6 hydrocarbons, N2, CO2 are added. This is hydrogen that has been obtained from sources other than ammonia; it has therefore not been obtained from ammonia and is therefore non-ammonia-based hydrogen. This can be green, blue, grey, turquoise or pink hydrogen, for example. These “colours” refer to the colouring in connection with the underlying production method. Green hydrogen is produced, for example, by the electrolysis of water using electricity from renewable energies, or by the gasification or fermentation of biomass, or the steam reforming of biogas - what all green hydrogen production methods have in common is that it is CO2-free. With blue hydrogen, the CO2 produced during production is stored so that it does not enter the atmosphere; for example , if it was produced by sequestering carbon dioxide CO2 .Turquoise hydrogen is produced by separating the resulting carbon into carbon dioxide. Pink hydrogen is produced using nuclear power. A mixture of one or more of these "colors" of hydrogen is also possible. Grey hydrogen is produced from fossil fuels—for example, from natural gas using steam reforming—with the resulting CO2 being released predominantly into the atmosphere.
[0076] Other colors of hydrogen are also possible. A mixture of one or more of these "colors" of hydrogen is also possible.
[0077] Syngas or synthesis gas refers to industrially produced gas mixtures that primarily contain carbon monoxide and hydrogen, along with varying amounts of other gases, such as carbon dioxide. Synthesis gas can, in principle, be produced from solid, liquid, and gaseous feedstocks. Liquid feedstocks for synthesis gas include, for example, various crude oil distillates, both low-boiling and high-boiling fractions. The most important gaseous reactant for synthesis gas production is natural gas.
[0078] Production methods include, for example, steam reforming of natural gas or liquid hydrocarbons, or gasification of coal, biomass or other residues.
[0079] A possible composition of synthesis gas is, for example, carbon monoxide C0=41 vol%, carbon dioxide CO2=14 vol%, hydrogen H2= 34 vol%, methane CH4= 5 vol%, hydrocarbons C2-C6= 2 vol%, nitrogen N2= 4 vol%.
[0080] One or more members of the second group can be added to the processing gas.
[0081] Members of the first or second group could also be added to the top gas or the processing gas before the start or before the completion of the processing; however, in the case of processing, it is preferable to add them after the completion of the processing, i.e. to the processing gas.
[0082] It is advantageous to use green ammonia NH3 and green hydrogen H2 simultaneously, as this is particularly cost-effective and allows for a particularly effective reduction of the CCT load in the process product. It is particularly advantageous to increase the amount of green ammonia NH3 used if the amount of green hydrogen H2 used should or must be reduced—for example, for availability or cost reasons.
[0083] The amount of green hydrogen H2 used can also be increased if the amount of green ammonia NH3 used should or must be reduced - for example, for reasons of availability or cost.
[0084] According to one embodiment, after combining top gas or processing gas and at least one member of the first group, at least one member of the second group is added to the resulting gas mixture. The gas mixture present after combining top gas or processing gas and at least one member of the first group is a precursor of the reducing gas; at least one member of the second group is added to this precursor. The resulting gas mixture can be the reducing gas or a precursor of the reducing gas. If it is a precursor, further steps are carried out, such as admixing additional components or heating to the temperature desired upon introduction into the reduction reactor or chemical reactions leading to a change in the composition.
[0085] Before at least one member of the second group is added to the gas mixture resulting from the combination of top gas or processing gas with at least one member of the first group, further modifications to this gas mixture can occur, such as the addition of additional components or heating, or chemical reactions leading to a change in composition. Heating can be achieved, for example, using electrically operated heating devices.
[0086] Heating can be achieved indirectly via gas burners, for example. In one variant, the precursor is also heated from the resulting exhaust gas via heat exchangers. Either natural gas or top gas can serve as the fuel for the gas burners. Top gas is advantageous because its chemical energy is utilized within the reduction process.
[0087] Chemical reactions leading to a change in composition can be induced, for example, by reforming the precursor—especially when natural gas is added. Heating in a reformer used for this purpose can be achieved indirectly, for example, via gas burners; in one variant, the precursor is also heated from the resulting exhaust gas via heat exchangers. Either natural gas or top gas, for example, can serve as the basis for the fuel for the gas burners; the use of top gas is advantageous because its chemical energy is utilized within the reduction process.
[0088] According to one embodiment, after combining top gas or processing gas and at least one member of the second group, at least one member of the first group is added to the resulting gas mixture. The gas mixture present after combining top gas or processing gas and at least one member of the second group is a precursor of the reducing gas; at least one member of the first group is added to this precursor. The resulting gas mixture can be the reducing gas or a precursor of the reducing gas. If it is a precursor, further steps are carried out, such as admixing additional components or heating to the temperature desired upon introduction into the reduction reactor or chemical reactions leading to a change in the composition.
[0089] Before at least one member of the first group is added to the gas mixture resulting from the combination of top gas or processing gas with at least one member of the second group, further modifications can be made to this gas mixture, such as the addition of additional components or heating to the temperature desired upon introduction into the reduction reactor, or chemical reactions leading to a change in composition. Heating can be achieved, for example, using electrically operated heating devices.
[0090] Heating can be achieved indirectly via gas burners, for example. In one variant, the precursor is also heated from the resulting exhaust gas via heat exchangers. Either natural gas or top gas can serve as the fuel for the gas burners. Top gas is advantageous because its chemical energy is utilized within the reduction process.
[0091] Chemical reactions leading to a change in composition can be initiated, for example, by reforming the precursor—especially when natural gas is added. Heating in a reformer used for this purpose can be achieved indirectly, for example, via gas burners. In one variant, the precursor is also heated from the resulting exhaust gas via heat exchangers. Either natural gas or top gas can serve as the fuel for the gas burners.
[0092] Ammonia can be added in the top gas, in the processing gas, or in the precursor to the reducing gas. When using a reduction reactor that has a bustle for introducing reducing gas into the interior containing metal oxide material where the reduction reactions take place, ammonia can, for example, be added to the gas leading to the bustle.
[0093] According to one embodiment, it is a process for the reduction of metal oxide-containing material, which is carried out in a reduction reactor with a cooling zone and / or a product cooler, wherein it is characterized in that ammonia is introduced into the cooling zone of the reduction reactor and / or the product cooler.
[0094] The ammonia is preferably introduced in gaseous form. The ammonia is split in the reduction reactor, with the reactions occurring being predominantly endothermic. Splitting already occurs in the cooling zone. Ammonia introduced into the cooling zone therefore contributes to cooling on the one hand, because it is split endothermically, and on the other hand, it contributes to reduction reactions in the reduction reactor.
[0095] Cooling with ammonia can, for example, be controlled so that the temperature of the reduced material removed from the reduction reactor reaches a desired temperature for further processing. For example, if the hot DRI - HDRI - removed from the reduction reactor is subsequently compacted, a different temperature may be desired than if it is fed into an EAF.
[0096] Another object of the invention is a device for reducing metal oxide-containing material, comprising:
[0097] - a reduction reactor,
[0098] - a top gas outlet for the discharge of top gas from the reduction reactor, at least one supply line for ammonia contribution,
[0099] - a preparation plant for the preparation of reducing gas, into which at least one feed line for ammonia contribution flows,
[0100] - a supply line for supplying reducing gas and / or a precursor of the reducing gas to the reduction reactor, characterized in that the top gas outlet opens into the preparation plant.
[0101] The device for reducing metal oxide-containing material may comprise one or more reduction reactors.
[0102] The device for reducing metal oxide-containing material may comprise one or more top gas outlets.
[0103] The device for reducing metal oxide-containing material can comprise one or more feed lines for ammonia contribution; these are suitable for the addition of liquid ammonia, or suitable for the addition of gaseous ammonia, or suitable for the addition of both liquid ammonia and gaseous ammonia, or suitable for the addition of hydrogen H2 obtained from ammonia by splitting it - pure or in a mixture with nitrogen N2.
[0104] The device for reducing material containing metal oxide can comprise one or more supply lines. With such a device, ammonia NH3 can be used to obtain reducing gas. The reducing gas is prepared in the preparation plant using ammonia NH3. The preparation plant can for this purpose comprise one or more cracking plants for cracking ammonia. The preparation plant can for this purpose also comprise one or more mixing devices which mix ammonia - liquid or gaseous - and / or at least one of its cracking products hydrogen H2 and nitrogen N2 with further components; they can also mix mixtures of the cracking products with further components. The preparation plant can also comprise one or more component feed lines for supplying components used in the preparation of the reducing gas.The preparation plant may also comprise one or more separation devices for separating the gas mixture of hydrogen H2 and nitrogen N2 obtained during the splitting of ammonia. Separation is understood not only to mean complete separation, but also enrichment or depletion of hydrogen H2 or nitrogen N2, respectively. For example, in the preparation plant, a feed line for the ammonia contribution may lead into a line carrying the top gas, with the outlet being understood as a mixing device. Thus, reducing gas can be prepared using ammonia and top gas as components.
[0105] For example, in the preparation plant, a supply line for the ammonia contribution can lead into a line carrying the processing gas, with the outlet being understood as a mixing device. Thus, reducing gas can be prepared using ammonia and processing gas as components. For example, in the preparation plant, a supply line for the ammonia contribution can lead into a line carrying the precursor of the reducing gas, with the outlet being understood as a mixing device. Thus, reducing gas can be prepared using ammonia.
[0106] If, for example, a reduction reactor with a bustle is used, reducing gas is supplied to the reduction reactor or its bustle via the supply line. This reducing gas is created by adding ammonia via a supply line for the ammonia contribution into a line carrying the top gas. The supply line also serves as a preparation system and mixing device, since the top gas and ammonia mix as they flow through and the reducing gas is prepared. The supply line can also be part of the preparation system in other ways; for example, if feed lines for feeding additional components into the precursor gas open into the supply line, or if heating devices are present in the supply line.
[0107] Where appropriate, the preparation plant includes ammonia heating facilities to allow ammonia to be heated prior to addition to top gas and / or make-up gas.
[0108] If necessary, the top gas outlet comprises one or more processing units; in this case, processing gas is fed to the processing unit through the top gas outlet. The processing units may, for example, be a dedusting unit—dry or wet—or a cooling unit, a compression unit, a heating unit, a cooling unit, a water vapor adjustment unit, or a desulfurization unit. It is also possible for one processing unit to fulfill multiple processing functions—for example, a cooling unit may also act as a water vapor adjustment unit.
[0109] According to a preferred embodiment, the top gas outlet comprises at least one treatment system, which is a device for reducing the nitrogen content. Thus, the nitrogen content of the top gas can be reduced, and a treatment gas with a lower nitrogen content than the top gas can be provided.
[0110] This can, for example, be a device for reducing the nitrogen content on the basis of different permeation rates, a device for reducing the nitrogen content using different adsorption forces - such as pressure swing adsorption, or a device for reducing the nitrogen content using different boiling temperatures.
[0111] According to a preferred embodiment, the preparation system comprises at least one feed line for feeding one or more members of the group consisting of:
[0112] - Natural gas
[0113] - Hydrocarbons, for example ethane C2H6, propane CaHs, butane C4H10,
[0114] - Hydrogen,
[0115] - Carbon monoxide,
[0116] - coke oven gas,
[0117] - Syngas .
[0118] For example, a natural gas feed line, a hydrogen feed line, a carbon monoxide feed line, a coke oven gas feed line, a syngas feed line, a hydrocarbon feed line.
[0119] One or more or all feed lines may also be suitable for feeding several group members, for example a natural gas / syngas / coke oven gas feed line.
[0120] Due to the presence of the feed lines - and, if necessary, mixing devices - members of the second group can be added to the top gas and / or the processing gas.
[0121] According to a preferred embodiment, the reduction reactor has a cooling zone and / or a product cooler, and an ammonia feed line opens into the cooling zone and / or the product cooler. A further subject matter of the present application is a signal processing device with a machine-readable program code, characterized in that it has control commands for carrying out a method according to the invention. A further subject matter is a signal processing device for carrying out the method according to one of claims 1 to 7. The signal processing device is part of a control and / or regulation of a device for reducing metal oxide-containing material.
[0122] A further subject matter of the present application is a machine-readable program code for a signal processing device - which is part of a control and / or regulation of a device for the reduction of metal oxide-containing material -, characterized in that the program code has control commands which cause the signal processing device to carry out a method according to the invention. A further subject matter is a computer program product comprising commands for a signal processing device - which is part of a control and / or regulation of a device for the reduction of metal oxide-containing material - which, when the program for the signal processing device is executed, cause the latter to carry out the method according to one of claims 1 to 7.
[0123] A further subject matter of the present application is a storage medium having a machine-readable program code according to the invention stored thereon. A further subject matter is a storage medium having a computer program stored thereon for carrying out the method according to one of claims 1 to 7. A further subject matter of the present application is a control and / or regulation of a device for reducing metal oxide-containing material using a computer containing a computer program product, comprising instructions which, when the computer executes the computer program, cause the computer to carry out the steps of a method according to one of claims 1 to 7.
[0124] A further subject matter of the present application is a computer program product comprising instructions which, when the computer program is executed by a computer, cause the computer to carry out the steps of a method according to one of claims 1 to 7. A further subject matter of the present application is a computer-readable data carrier on which such a computer program product is stored.
[0125] Short description of the drawings
[0126] The present invention is described below by way of example with reference to several schematic figures.
[0127] Figure 1 shows schematically the implementation of a variant of the method according to the invention in a variant of the device according to the invention for the reduction of metal oxide-containing material
[0128] Figure 2 shows schematically another variant.
[0129] Figure 3 shows another variant.
[0130] Figure 4 shows a schematic representation of another variant. Figure 5 shows a schematic representation of another variant.
[0131] Description of the embodiments
[0132] Examples
[0133] Figure 1 shows schematically the implementation of a method according to the invention in a device 1 according to the invention for reducing material containing metal oxide. Material 3 containing metal oxide, in this case material containing iron oxide, is introduced into a reduction reactor 2, in this case a reduction shaft, where it forms a fixed bed 4. Reducing gas is used to reduce the material 3 containing metal oxide in the reduction reactor 2. Top gas is discharged from the reduction reactor 2 via a top gas outlet 5. The top gas outlet 5 opens into the preparation plant 6 for preparing reducing gas. A feed line for an ammonia contribution 7 opens into the preparation plant 6. In the preparation plant 6, reducing gas is prepared using ammonia NH₄ and using top gas as a component.The reducing gas obtained using ammonia and top gas is fed via the supply line 8 to the reduction reactor 2 containing the metal oxide-containing material 3. In the preparation system 6, the top gas is mixed with ammonia, and the resulting gas mixture is the reducing gas. The top gas is thus used directly in the preparation of the reducing gas.
[0134] Figure 2 shows, largely analogous to Figure 1, a schematic variant in which the top gas is used indirectly in the preparation of the reducing gas. Processing gas is fed to the preparation system 6 via the top gas outlet 5. The processing gas is obtained by processing the top gas; in the top gas outlet 5 there is a device for reducing the nitrogen content 9, and a nitrogen-depleted stream of processing gas is fed to the preparation system 6 via the top gas outlet 5. In the preparation system 6, the processing gas is mixed with ammonia, and the gas mixture obtained is the reducing gas. In Figure 2, as a result of the reduction in the nitrogen content, a portion of the top gas is used as a component in the preparation of the reducing gas.
[0135] Figure 3 schematically shows, largely analogous to Figure 2, a variant in which the processing plant 6 includes a feed line for natural gas 10. This makes it possible, after combining the processing gas and ammonia, to add natural gas to the resulting gas mixture, or, after combining the processing gas and natural gas, to add ammonia to the resulting gas mixture. The resulting gas mixture can serve as a precursor to the reducing gas and be converted into reducing gas in a reformer (not shown separately).
[0136] Figure 4 schematically shows, largely analogous to Figure 2, a variant in which an ammonia feed line 11 opens into the cooling zone 12 of the reduction reactor 2. This allows ammonia to be introduced into the cooling zone during direct reduction in the reduction reactor 2.
[0137] Figure 5 schematically shows a variant, largely analogous to Figure 1, in which the bustle 13 of the reduction reactor is also shown. Reduction gas is fed to the bustle 13 via supply line 8. To prepare the reduction gas, ammonia is fed into the top gas line 14 via a supply line for ammonia contribution 7. The supply line 8 also counts as a preparation system and a mixing device, since ammonia and top gas are mixed in it.
[0138] List of reference symbols
[0139] 1 Device for the reduction of metal oxide-containing material
[0140] 2 Reduction reactor
[0141] 3 metal oxide-containing material
[0142] 4 fixed beds
[0143] 5 Top gas discharge
[0144] 6 Preparation system
[0145] 7 Supply line for ammonia contribution
[0146] 8 Supply line
[0147] 9 Device for reducing the nitrogen content
[0148] 10 Natural gas supply line
[0149] 11 Ammonia supply line
[0150] 12 cooling zones
[0151] 13 Bustle
[0152] 14 Topgas carrying line
Claims
Claims 1. Process for the reduction of metal oxide-containing material (2) , wherein reducing gas obtained using ammonia NHa is used, wherein the reducing gas is supplied to a reduction reactor (2) containing the metal oxide-containing material, and a top gas is discharged from the reduction reactor, characterized in that at least a subset of the top gas, optionally after processing of the top gas, is used as a component in the preparation of the reducing gas.
2. The method according to claim 1, characterized in that the processing of the top gas withdrawn from the reduction reactor (2) comprises a process step for reducing the nitrogen content.
3. Method according to claim 1 or 2, characterized in that at least one member of the first group consisting of: is added to the top gas and / or the processing gas during the preparation of the reduction gas. - Ammonia, - hydrogen derived from ammonia is added.
4. Method according to one of claims 1 to 3, characterized in that at least one member of the second group consisting of: is added to the top gas and / or the processing gas during the preparation of the reduction gas. natural gas, Hydrocarbons, Hydrogen, - Carbon monoxide, - Coke oven gas, - Syngas comprising several components from the group of components consisting of CO, H2, CH4, C2-C6 hydrocarbons, N2, CO2, is added.
5. Method according to claim 4, characterized in that, after combining top gas or processing gas and at least one member of the first group, at least one member of the second group is added to the resulting gas mixture.
6. Method according to claim 4, characterized in that, after combining top gas or processing gas and at least one member of the second group, at least one member of the first group is added to the resulting gas mixture.
7. Method according to any one of claims 1 to 6, wherein it is carried out in a reduction reactor (2) with a cooling zone (12) and / or a product cooler, characterized in that ammonia is introduced into the cooling zone (12) of the reduction reactor (2) and / or the product cooler.
8. Device (1) for reducing metal oxide-containing material (3) , comprising: - a reduction reactor (2) , - a top gas discharge (4) for the discharge of top gas from the reduction reactor (2) , at least one feed line for ammonia contribution (7) , - a preparation plant (6) for the preparation of reducing gas, into which at least one supply line for ammonia contribution (7) opens, a supply line (8) for supplying reducing gas and / or a precursor of the reducing gas to the reduction reactor (2) , characterized in that the top gas outlet (5) leads into the preparation plant (6) .
9. Device according to claim 8, characterized in that the top gas discharge (5) comprises at least one processing plant which is a device for reducing the nitrogen content (9).
10. Device according to claim 8 or 9, characterized in that the preparation plant (6) has at least one feed line (10) for feeding one or more members of the group consisting of: - Natural gas, - Hydrocarbons, - Hydrogen, - Carbon monoxide, - Coke oven gas, - Syngas, includes .
11. Device according to one of claims 8 to 10, wherein the reduction reactor (2) has a cooling zone (12) and / or a product cooler, characterized in that an ammonia supply line (11) opens into the cooling zone (12) and / or the product cooler.
12. Signal processing device with a machine-readable program code, characterized in that it has control commands for carrying out a method according to one of claims 1 to 7.
13. Machine-readable program code for a signal processing device, characterized in that the program code includes control commands which cause the signal processing device to carry out a method according to one of claims 1 to 7.
14. Storage medium with a machine-readable program code stored thereon according to claim 13.
15. Control and / or regulation of a device for the reduction of metal oxide-containing material with a computer comprising a computer program product, comprising instructions which, when the computer program is executed by the computer, cause it to perform the steps of a method according to any one of claims 1 to 7.