Controlling temperature and noₓ content for a reduction gas

Abstract

The invention relates to a method for reducing a metal oxide-containing material. A reduction gas which at least contains hydrogen is supplied to a reduction reactor (3), and a hydrogen-containing top gas is discharged from the reduction reactor (3). A sub-quantity of the top gas is supplied to gas burners (6), which are used in the preparation of the reduction gas, as a component of the fuel gas. If the content of hydrogen in the reduction gas and / or in the top gas increases, the content of water vapor in the fuel gas is increased. A device for this purpose comprises a reduction reactor (3), a top gas discharge (5) for discharging a top gas out of the reduction reactor (3), a preparation system (7) which comprises at least one gas burner (6) for preparing reduction gas, and a supply line (8) for supplying a sub-quantity of the top gas to the at least one gas burner (6) as a fuel gas component. The device is characterized by also comprising at least one member of the group consisting of the two members a) at least one device (9) for determining the water vapor content in the reduction gas and / or in the top gas and b) a device (9a) for ascertaining an increase of the proportion of hydrogen in the reduction gas and / or in the top gas as well as a device (10) for controlling and / or regulating the water vapor content in the fuel gas using the hydrogen content in the reduction gas and / or in the top gas.

Description

[0001] Description

[0002] Control of temperature and NO x -Content for reducing gas

[0003] field of technology

[0004] The application relates to a method and device for reducing material containing metal oxide, using reducing gas.

[0005] State of the art

[0006] It is known to reduce materials containing metal oxides, such as iron oxide, such as ores, using reducing gas. For example, direct reduction with reducing gas in a reduction unit, such as a reduction shaft. In conventional processes currently used on a large scale, the reducing gas is predominantly carbon-based—for example, carbon monoxide (CO) or methane (CH4)—from natural gas. Therefore, large amounts 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 those based on carbon from natural gas. The greater the proportion of hydrogen (H2), which is CO2-neutral with respect to reduction reactions, in the reducing gas, the less CO2 is emitted. Depending on the availability of natural gas and hydrogen, the ratio of their contribution to the reducing gas can be varied by mixing different amounts.

[0008] The more hydrogen is available, the more climate-problematic contributions based on carbon from natural gas can be avoided.

[0009] It is advantageous to operate existing plants and processes in which the reducing gas is predominantly based on carbon from natural gas with increased proportions of hydrogen in the reducing gas. This allows for flexible responses to the availability of natural gas and hydrogen and allows the utilization of existing plant investments. At least until sufficient quantities of hydrogen are available for the use of completely hydrogen-based reducing gases, reducing gas will still have to rely on carbon from natural gas.

[0010] It is common practice to feed reducing gas into a reduction reactor containing the metal oxide-containing material and to discharge a top gas 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, such as 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, and it also has a calorific value. To utilize this reducing power, top gas is often used as a component in the preparation of fresh reducing gas.

[0011] The reducing gas is often heated in a gas heating device using gas burners to achieve the desired temperature for the reduction reactions. In processes where the production of the reducing gas is based on reforming a precursor gas—for example, natural gas—energy for the reforming is often provided by gas burners.

[0012] Gas burners require a fuel gas and an oxidizing gas—for example, air. During combustion, the fuel gas is oxidized, releasing energy.

[0013] It is known that due to its calorific value, suitable top gas is used as a fuel gas.

[0014] As the proportion of hydrogen in the reducing gas increases, so does the proportion of hydrogen in the top gas. When used as a fuel gas, this has the disadvantage that the adiabatic flame temperature increases during combustion. The increase in the adiabatic flame temperature can have adverse effects:

[0015] - when using air as oxidizing gas, a significant amount of nitrogen is present; with increasing adiabatic flame temperature, more undesirable nitrogen oxides NO are formed XHowever, the nitrogen can also come from combustible nitrogen gases, such as ammonia NH3, which are present in the fuel gas – so-called fuel nitrogen – or from gaseous nitrogen N2 in the fuel gas. For energy optimization, gases such as oxidizing gas, fuel gas, and precursors of reducing gas are often heated by heat exchange with the exhaust gas of the gas burner. Heat transfer often occurs by radiation. Increasing adiabatic flame temperature can adversely affect radiation-based heat transfer.

[0016] Summary of the invention

[0017] Technical task

[0018] It is the object of the present invention to provide a contribution to reducing at least some of the aforementioned problems.

[0019] Technical solution

[0020] The task is solved by a

[0021] A process for the reduction of metal oxide-containing material, wherein a reducing gas containing at least hydrogen, optionally also carbon carrier, is fed to a reduction reactor containing the metal oxide-containing material, and a hydrogen-containing top gas is discharged from the reduction reactor, characterized in that a portion of the top gas is fed to gas burners used in the preparation of the reducing gas as a component of the fuel gas, and as the proportion of hydrogen in the reducing gas and / or in the top gas increases, the water vapor content of the fuel gas is increased.

[0022] The metal oxide-containing material is preferably iron oxide-containing material.

[0023] The reducing gas contains at least hydrogen as a reducing component. It can also consist of hydrogen. Optionally, the reducing gas also contains one or more gaseous carbon carriers as additional reducing components. Carbon carriers are provided, for example, by natural gas; these include carbon monoxide (CO) introduced by or generated from natural gas, or methane (CH4).

[0024] This could 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, for example, is produced by electrolysis of water using electricity from renewable energies, or by gasification or fermentation of biomass, or 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 escape into the atmosphere; for example, if it was produced by sequestering the resulting carbon dioxide. With turquoise hydrogen, e is produced by capturing the resulting carbon. With pink hydrogen, hydrogen is produced using nuclear power.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.

[0025] Other colors of hydrogen are also possible.

[0026] A mixture of one or more of these “colors” of hydrogen is also possible.

[0027] If carbon carriers are present as additional reducing components, the following applies: the ratio of hydrogen to carbon carriers in the reducing gas can be varied, for example, by combining different amounts during the preparation of the reducing gas. For example, the ratio can be varied so that the proportion of hydrogen in the reducing gas increases.

[0028] The reducing gas is the gas introduced into the reduction reactor with its composition and temperature at the time of introduction. Before this composition and temperature are achieved, a precursor of the reducing gas is present, on the basis of which the reducing gas is prepared. Preparation may include, for example, the addition of additional components, heating, or reforming. Preparation may also involve chemical reactions occurring in the precursor without external intervention, which, for example, change the chemical composition or temperature. Changes to the preparation may alter the proportion of hydrogen in the reducing gas.

[0029] In any case, gas burners are used to prepare the reducing gas, for example, for heating and / or reforming. 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.

[0030] 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.

[0031] A top gas is discharged from the reduction reactor. The top gas is formed from the reducing gas flowing 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, such as 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. The top gas contains hydrogen.

[0032] Gas burners require a fuel gas for combustion. A portion of the top gas is supplied to the gas burners used in the preparation of the reducing gas as a component of the fuel gas required for combustion; if several gas burners are used, this is supplied to at least one gas burner. For example, 100 Nm 3 Top gas a subset of 10 Nm 3 used as a component of the fuel gas. Before being used as a component of the fuel gas, the top gas can be subjected to treatment steps, for example, dedusting the top gas, heating the top gas, cooling the top gas, and adjusting the water vapor content of the top gas.

[0033] The subset of the top gas can be one of several components of the fuel gas, for example when another gas - such as natural gas - with calorific value is added and the gas mixture is then used as fuel gas.

[0034] The subset of the top gas can also be the only component of the fuel gas, in which case the fuel gas corresponds to this subset.

[0035] If there are multiple components of the fuel gas, the following applies: the fuel gas is formed by combining all components of the fuel gas; before all components are combined, a precursor of the fuel gas exists.

[0036] Measures to increase the water vapor content in one or more components of the fuel gas or in a precursor of the fuel gas also lead to an increase in the water vapor content of the fuel gas.

[0037] If the proportion of hydrogen in the reducing gas and / or top gas increases, the water vapor content of the fuel gas is increased. To this end, measures are taken which bring about the presence of additional water vapor in the fuel gas compared to a reference state. The increase in the water vapor content of the fuel gas is preferably carried out in a controlled and / or regulated manner, i.e. using a device for controlling and / or regulating the water vapor content in the fuel gas. In this case, control and / or regulation is carried out with a target value or a target value range. The target value or the target value range arise, for example, from the desired extent of the reduction in the adiabatic flame temperature and / or from the desired limitation of temperature peaks within the flame.

[0038] An increase in the proportion of hydrogen in the reducing gas and / or top gas is detected using a device for detecting an increase in the proportion of hydrogen in the reducing gas and / or top gas, or using a device for determining the hydrogen content in the reducing gas and / or top gas. When determining the hydrogen content in the reducing gas and / or top gas, an increase in the proportion of hydrogen in the reducing gas and / or top gas can also be detected.

[0039] Preferably, the hydrogen Fh content in the fuel gas is at least 65 vol%, particularly preferably at least 70 vol% - in each case based on 0 vol% water content in the fuel gas.

[0040] Advantageous effects of the invention

[0041] An increase in the water vapor content of the fuel gas during combustion results in a lower adiabatic flame temperature compared to a fuel gas with the same water vapor content except for the increased water vapor content. The problems described above regarding nitrogen oxide formation and heat transfer due to the increased adiabatic flame temperature resulting from an increasing hydrogen content can thus be reduced or avoided.

[0042] Another advantage is that the reduction in the adiabatic flame temperature enabled by the invention does not require a reduction in the temperature level of the fuel gas and the oxidizing gas. This allows a constant amount of energy to be extracted from the exhaust gas of the gas burner via heat exchange, which is beneficial with regard to the release of the exhaust gases into the environment. Releasing the exhaust gases at a higher temperature—because less heat is extracted from the fuel gas and oxidizing gas to achieve a reduction in the flame temperature by lowering the temperature of these gases—is disadvantageous due to the lower amount of energy extracted via heat exchange.

[0043] Typically, the water vapor content of the top gas is adjusted to a target value to ensure the most reproducible properties possible for easily controllable further use of the top gas. For this purpose, it is typically subjected to countercurrent conditioning with water, which is carried out in a gas conditioner. Different portions of the top gas, intended for different uses with different water vapor content requirements—for example, use as a component of the reducing gas, use as a component of a fuel gas—are typically conditioned in different gas conditioning channels with water at different temperatures. According to one embodiment, the water vapor content of the fuel gas is increased by raising the temperature of the water used to condition the portion of the top gas.The portion of the top gas leaving the gas conditioner is saturated; as the water temperature increases, the temperature of the portion of the top gas leaving the gas conditioner increases, and thus the amount of water vapor contained at saturation.

[0044] Typically, the top gas intended for use as a component of the reducing gas is conditioned in dedicated gas conditioning channels using warm water. Compared to an initial state with a specific water vapor content of the top gas before conditioning and a specific target water vapor content after conditioning, the higher the water vapor content of the top gas before conditioning—i.e., the more water needs to be condensed to maintain an unchanged target—the more advantageous it is to use water at a lower temperature for conditioning compared to the initial state. The demand for the warm water provided to achieve the initial state thus decreases.According to one embodiment, the temperature of the water used for conditioning the portion of the top gas intended as a component of the fuel gas is increased by using warm water intended for conditioning top gas intended as a component of the reducing gas - this may constitute a portion of the water for conditioning the top gas or may be the entire water for conditioning the top gas.

[0045] In this way, the infrastructure for producing hot water can be used effectively even when the demand for hot water to condition the reducing gas decreases.

[0046] According to one embodiment, the water vapor content of the fuel gas is increased by adding water H2O to the fuel gas - or to a component or precursor of the fuel gas. Thus, one or more or all members of the group consisting of three members

[0047] - fuel gas,

[0048] - component of the fuel gas,

[0049] - Precursor of the fuel gas water H2O is added.

[0050] The water can be added as liquid H2O. The water H2O can be added as water vapor H2O g added. The fuel gas is created by combining all components of the fuel gas. Before all components are combined, a fuel gas precursor exists.

[0051] According to a variant of the process according to the invention, the fuel gas – or a precursor of the fuel gas – is heated before the fuel gas is burned. This occurs, for example, by heat exchange with exhaust gas from a reformer and / or a gas heating device; for example, exhaust gas from the reformer and / or gas heating device operated with the gas burners supplied with the fuel gas. Preferably, water H2O is added to the fuel gas – or a precursor of the fuel gas – after the fuel gas – or the precursor of the fuel gas – has been heated. More water H2O can then be absorbed due to the higher temperature. This is particularly advantageous if one component of the fuel gas being added is hydrogen H2, since hydrogen H2 is usually largely dry and thus its percentage water content decreases after it enters a gas mixture.As mentioned, treatment steps such as dedusting can be carried out on the top gas before it is used as a component of the fuel gas. According to one embodiment, the top gas intended for use as a component of the fuel gas is at least partially dedusted under dry conditions. With dry dedusting, there is practically no loss of water vapor content, which would then have to be compensated for when the water vapor content increases; therefore, it is advantageous to dry dedust the portion of the top gas intended as a component of the fuel gas. If hydrogen H2 is one component of the fuel gas that is added, it is advantageous to add it after dry dedusting. This is because hydrogen H2 is usually largely dry and thus, after it enters a gas mixture, its percentage water content decreases.After dry dedusting, the water vapor content is usually high enough that a reduction by adding hydrogen requires little or no effort to meet or exceed a desired minimum value.

[0052] With dry dust removal, there is virtually no loss of sensible heat. Therefore, with dry dust removal, the fuel gas requires little or no preheating. The energy remaining in the top gas can be used, for example, to preheat hydrogen, combustion air, process gas, or reducing gas.

[0053] Another subject of the present application is a device for reducing metal oxide-containing material, comprising:

[0054] - a reduction reactor,

[0055] - a top gas outlet for the discharge of top gas from the reduction reactor,

[0056] - a preparation system comprising at least one gas burner for preparing reducing gas,

[0057] - a supply line for supplying a portion of the top gas as a fuel gas component to the at least one gas burner, characterized in that it also comprises

[0058] - at least one member of the group consisting of the two members a) at least one device for determining the water vapor content in the reducing gas and / or in the top gas, and b) device for detecting an increase in the proportion of hydrogen in the reducing gas and / or in the top gas, a device for controlling and / or regulating the water vapor content in the fuel gas, taking into account the hydrogen content in the reducing gas and / or in the top gas.

[0059] The device for reducing metal oxide-containing material may comprise one or more reduction reactors.

[0060] The device for reducing metal oxide-containing material also comprises a reducing gas supply line through which reducing gas is supplied to the reduction reactor.

[0061] The device for reducing metal oxide-containing material may comprise one or more top gas outlets.

[0062] The device for reducing material containing metal oxide may comprise one or more preparation systems for preparing reducing gas.

[0063] A preparation plant for preparing reducing gas may comprise one or more gas burners.

[0064] The device for reducing metal oxide-containing material can comprise one or more supply lines for supplying a portion of the top gas as a fuel gas component to the at least one gas burner. These are suitable for supplying a portion of the top gas, together with other components of the fuel gas, to the gas burners as fuel gas. Other components of the fuel gas can be fed in, for example, through feed lines opening into the supply line carrying the portion of the top gas, thereby producing the fuel gas. The device for reducing metal oxide-containing material comprises at least one device for determining the water vapor content in the reduction gas and / or in the top gas; it can also comprise several such devices. The determination of the water vapor content can be based, for example, on a calculation based on the gas temperature and / or water temperature.

[0065] The device for reducing metal oxide-containing material comprises a device for controlling and / or regulating the water vapor content in the fuel gas, taking into account the hydrogen content in the reducing gas and / or in the top gas; it may also comprise several such devices.

[0066] With such a device, the goal of controlling and / or regulating the water vapor content in the fuel gas, taking into account the hydrogen content in the reducing gas and / or the top gas, can be achieved. In this way, a method according to the invention can be carried out. Naturally, the device according to the invention for reducing metal oxide-containing material also includes a reducing gas supply line, via which reducing gas—containing at least hydrogen and optionally also carbon carriers—is supplied to the reduction reactor.

[0067] According to a variant of the device according to the invention for reducing material containing metal oxide, a feed line is also provided for supplying further fuel gas components to the gas burner.

[0068] According to one variant, a device according to the invention for reducing metal oxide-containing material comprises a device for detecting an increase in the proportion of hydrogen in the reducing gas and / or in the top gas. This device can be used to determine whether an increase in the proportion of hydrogen in the reducing gas and / or in the top gas is occurring.The device for detecting an increase in the proportion of hydrogen in the reducing gas and / or in the top gas can be integrated into the device for determining the water vapor content in the reducing gas and / or in the top gas, so that only a single device with two suitabilities is present - or it can be designed separately from the device for determining the water vapor content in the reducing gas and / or in the top gas, so that two devices are present - a device for detecting an increase in the proportion of hydrogen in the reducing gas and / or in the top gas, and a device for determining the hydrogen content in the reducing gas and / or in the top gas.

[0069] Preferably, the device for detecting an increase in the proportion of hydrogen in the reducing gas and / or in the top gas is a device for determining the hydrogen content in the reducing gas and / or in the top gas.

[0070] According to one embodiment, the device for controlling and / or regulating the water vapor content in the fuel gas, taking into account the hydrogen content in the reducing gas and / or the top gas, comprises at least one gas conditioner. In a gas conditioner, the gas is conditioned with respect to its water vapor content, i.e., a measure is taken that leads to the achievement of a target value for the water vapor content. The measure in a gas conditioner is to conduct the gas stream to be conditioned in countercurrent with water. Heat and water are exchanged between the gas phase and the liquid phase.

[0071] In a device according to the invention, the gas conditioner is designed such that it can be operated at different water temperatures. For this purpose, it can, for example, have different water supply lines, each connected to water from water sources at different temperatures. For this purpose, it can, for example, have heating devices and / or cooling devices for heating and / or cooling the supplied water.

[0072] According to one embodiment, the gas conditioner has fuel gas conditioning channels for conditioning top gas provided as a component of the fuel gas with a water supply for fuel gas conditioning, and reducing gas conditioning channels for conditioning top gas provided as a component of the reducing gas with a hot water supply for reducing gas conditioning, wherein the hot water supply for reducing gas conditioning is suitable for supplying hot water for fuel gas conditioning to at least one fuel gas conditioning channel.

[0073] According to one embodiment, the device for reducing metal oxide-containing material comprises H2O addition lines suitable for supplying liquid water H2O f and / or gaseous water H2O g - i.e. water vapor - into pipes which

[0074] - fuel gas or

[0075] - components of the fuel gas.

[0076] For example, an H2O addition line can open into a line carrying fuel gas. Or it can open into a line carrying a component of the fuel gas, for example, a supply line for supplying a portion of the top gas as a fuel gas component to the at least one gas burner. The outlet can be arranged before and / or after—viewed in the flow direction toward the gas burner—the outlets of feed lines.

[0077] According to one embodiment, the device for reducing metal oxide-containing material comprises a dry dedusting device for dry dedusting top gas; preferably, this is suitable for dry dedusting at least a portion of the top gas intended for use as a component of the fuel gas.

[0078] Another subject of the present application is a

[0079] A signal processing device with a machine-readable program code, characterized in that it comprises control and / or regulating commands for implementing a method according to the invention. A further subject matter is a signal processing device for implementing a method according to one of claims 1 to 5.

[0080] A further subject matter of the present application is a machine-readable program code for a signal processing device, characterized in that the program code comprises control and / or regulating commands that 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 that, upon execution of the program for the signal processing device, cause the signal processing device to carry out the method according to one of claims 1 to 5.

[0081] 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 a method according to one of claims 1 to 5.

[0082] Short description of the drawings

[0083] The present invention is described below by way of example with reference to several schematic figures.

[0084] Figure 1 schematically shows an embodiment of a device according to the invention. Figure 2 schematically shows an embodiment largely analogous to Figure 1, with details of the FhO addition lines.

[0085] Figure 3 shows schematically an embodiment largely analogous to Figures 1 and 2 with details of dry dust removal.

[0086] Figure 4 shows schematically a further embodiment of a device according to the invention.

[0087] Figure 5 schematically shows a variant of the use of top gas not used for fuel gas. Description of the embodiments

[0088] Examples

[0089] Figure 1 schematically shows a device 1 for reducing metal oxide-containing material 2 with a reduction reactor 3. The metal oxide-containing material 2 is fed into the reduction reactor 3. The device 1 for reducing metal oxide-containing material 2 also comprises a reducing gas supply line 4, via which reducing gas containing at least hydrogen and optionally also carbon carriers is supplied to the reduction reactor 3. A hydrogen-containing top gas is discharged from the reduction reactor 3 via a top gas outlet 5. Reducing gas is prepared in a preparation system 7 comprising a gas burner 6 for preparing reducing gas. The gas burner 6 is operated with fuel gas. A portion of the top gas is supplied to the gas burner 6 as a fuel gas component; this occurs via a supply line 8 for supplying a portion of the top gas as a fuel gas component to the gas burner 6.A device 9 for determining the hydrogen content in the reducing gas and the top gas is also present. This determines whether there is an increase in the proportion of hydrogen in the reducing gas and / or the top gas. The positions shown for determining the hydrogen content are not necessarily those shown in Figure 1; the hydrogen content could also be determined at other positions; for example, it could be determined after dry dust removal. Taking into account the hydrogen content in the reducing gas and / or the top gas, a device 10, which is also present, for controlling and / or regulating the water vapor content in the fuel gas is used to increase the water vapor content of the fuel gas. This is represented by a dashed circle around sections of lines that conduct fuel gas components or fuel gas to the gas burner 6.A further fuel gas component is fed to the gas burner 6 via feed line 11; top gas and further fuel gas component are combined in the illustration because line 11 and supply line 8 merge; the combination of the further fuel gas component and the top gas produces fuel gas, which is fed to the gas burner 6.

[0090] According to one variant, the device 10 for controlling and / or regulating the water vapor content in the fuel gas, taking into account the hydrogen content in the reducing gas and / or in the top gas, comprises a gas conditioner, which is not shown separately for clarity. The gas conditioner is designed such that it can be operated at different water temperatures. For this purpose, it can, for example, have various water supply lines, each connected to water from water sources with different temperatures. For this purpose, it can, for example, have heating devices and / or cooling devices for heating and / or cooling the supplied water. The water vapor content of the fuel gas is thus increased by raising the temperature of the water used to condition the partial amount of the top gas.According to a variant not shown separately, the gas conditioner has fuel gas conditioning channels with a water supply for fuel gas conditioning, and reducing gas conditioning channels with a hot water supply for reducing gas conditioning. The hot water supply for reducing gas conditioning is suitable for supplying hot water for fuel gas conditioning to at least one fuel gas conditioning channel. The temperature of the water used in conditioning this portion of the top gas can then be increased by using hot water intended for conditioning the top gas intended as a component of the reducing gas.

[0091] Figure 2 shows, in a representation largely analogous to Figure 1, how H2O addition lines 12a, 12b, 12c are provided. Through these, liquid water H2O and / or gaseous water H2O gWater vapor, i.e., water vapor, is introduced into lines carrying fuel gas or fuel gas components. H2O addition line 12a opens into a fuel gas line. H2O addition lines 12b and 12c open into lines carrying fuel gas components. Thus, the water vapor content of the fuel gas can be increased by adding water (H2O) to the fuel gas—or a fuel gas precursor or fuel gas component.

[0092] Figure 3 shows, in a representation largely analogous to Figures 1 and 2, how the device 1 for reducing metal oxide-containing material contains a dry dedusting device 13 for the dry dedusting of top gas. This is suitable for the dry dedusting of at least a portion of the top gas intended for use as a component of the fuel gas, since it is arranged in the supply line 8. According to a variant not separately shown, the device 10 for controlling and / or regulating the water vapor content in the fuel gas can be designed such that it can influence the temperature in the dry dedusting device and in this way the water vapor content in the fuel gas can be controlled and / or regulated. Figure 4 shows, largely analogous to Figure 1, a schematic of a device 1 for reducing metal oxide-containing material 2 with a reduction reactor 3. The metal oxide-containing material 2 is fed into the reduction reactor 3.The device 1 for reducing metal oxide-containing material 2 also comprises a reducing gas supply line 4, via which reducing gas containing at least hydrogen and optionally also carbon carriers is supplied to the reduction reactor 3. A hydrogen-containing top gas is discharged from the reduction reactor 3 via a top gas outlet 5. Reducing gas is prepared in a preparation system 7 comprising a gas burner 6 for preparing reducing gas. The gas burner 6 is operated with fuel gas. A portion of the top gas is supplied to the gas burner 6 as a fuel gas component; this occurs via a supply line 8 for supplying a portion of the top gas as a fuel gas component to the gas burner 6. A device 9a is also present for detecting an increase in the proportion of hydrogen in the reducing gas and / or the top gas.This device 9a determines whether an increase in the hydrogen content in the reducing gas and / or the top gas is occurring. The positions shown for determining the hydrogen content are not necessarily as shown in Figure 4; the hydrogen content could also be determined at other positions; for example, it could be determined after dry dust removal.

[0093] The device 9a for detecting an increase in the proportion of hydrogen in the reducing gas and / or the top gas is, in the illustrated case, a device for determining the hydrogen content in the reducing gas and / or the top gas. Taking the hydrogen content in the reducing gas and / or the top gas into account, an increase in the water vapor content of the fuel gas is achieved using a device 10, which is also present, for controlling and / or regulating the water vapor content in the fuel gas. This is represented by a dashed circle around sections of lines that conduct fuel gas components or fuel gas to the gas burner 6.A further fuel gas component is fed to the gas burner 6 via feed line 11; top gas and further fuel gas component are combined in the illustration because line 11 and supply line 8 merge; the combination of the further fuel gas component and the top gas produces fuel gas, which is fed to the gas burner 6.

[0094] According to one variant, the device 10 for controlling and / or regulating the water vapor content in the fuel gas, taking into account the hydrogen content in the reducing gas and / or in the top gas, comprises a gas conditioner, which is not shown separately for clarity. The gas conditioner is designed such that it can be operated at different water temperatures. For this purpose, it can, for example, have various water supply lines, each connected to water from water sources with different temperatures. For this purpose, it can, for example, have heating devices and / or cooling devices for heating and / or cooling the supplied water. The water vapor content of the fuel gas is thus increased by raising the temperature of the water used to condition the partial amount of the top gas.According to a variant not shown separately, the gas conditioner has fuel gas conditioning channels with a water supply for fuel gas conditioning, and reducing gas conditioning channels with a hot water supply for reducing gas conditioning. The hot water supply for reducing gas conditioning is suitable for supplying hot water for fuel gas conditioning to at least one fuel gas conditioning channel. The temperature of the water used in conditioning this portion of the top gas can then be increased by using hot water intended for conditioning the top gas intended as a component of the reducing gas.

[0095] The contents shown in Figures 2 and 3 could, analogously to their combination with contents of Figure 1, also be combined with contents of Figure 4 instead of with contents of Figure 1.

[0096] For the sake of clarity, Figures 1 to 4 do not show what can happen to top gas that is not used as a fuel gas component. Figure 5 schematically shows how a variant of such use can occur, in a representation analogous to Figure 1 - top gas is combined with a reducing gas precursor 14, for example natural gas and / or hydrogen, and the mixture is introduced into the preparation system for preparing reducing gas. Top gas therefore serves as a reducing gas precursor. Such recirculation of top gas and its use in the preparation of reducing gas is known and therefore not described in detail. This variant shown in Figure 5 with regard to the use of top gas not used as a fuel gas component could also be combined with the contents shown in Figures 2 to 4.

[0097] The feed line 11 in Figures 1, 3, and 4 is optional; embodiments analogous to Figures 1, 3, and 4 are also possible without the feed line 11. List of reference symbols

[0098] 1 Device for the reduction of metal oxide-containing material

[0099] 2 metal oxide-containing material

[0100] 3 Reduction reactor

[0101] 4 Reducing gas supply line

[0102] 5 Top gas discharge

[0103] 6 gas burners

[0104] 7 Preparation system for the preparation of

[0105] Reducing gas

[0106] 8 Supply line

[0107] 9 Device for determining the

[0108] Water vapor content in the reducing gas and / or top gas

[0109] 9a Device for detecting an increase in the proportion of hydrogen in the reducing gas and in the top gas

[0110] 10 Device for controlling and / or regulating the water vapor content in the fuel gas

[0111] 11 Feed line

[0112] 12a, 12b, 12c FLO addition lines

[0113] 13 Dry dust extraction device

[0114] 14 reducing gas precursors

Claims

Claims 1. A process for the reduction of metal oxide-containing material, wherein a reducing gas containing at least hydrogen, and optionally also a carbon carrier, is supplied to a reduction reactor (3) containing the metal oxide-containing material, and a hydrogen-containing top gas is discharged from the reduction reactor (3), characterized in that a portion of the top gas is supplied to gas burners (6) used in the preparation of the reducing gas as a component of the fuel gas, and if the proportion of hydrogen in the reducing gas and / or in the top gas increases, the water vapor content of the fuel gas is increased.

2. Method according to claim 1, wherein the top gas is subjected to countercurrent conditioning with water in a gas conditioner, characterized in that the increase in the water vapor content of the fuel gas is carried out by increasing the temperature of the water used in the conditioning of the subset of the top gas.

3. Method according to claim 2, characterized in that the temperature of the water used for conditioning the subset of the top gas intended as a component of the fuel gas is increased by using hot water intended for conditioning top gas intended as a component of the reducing gas.

4. Method according to one of claims 1 to 3, characterized in that the increase in the water vapor content of the fuel gas is carried out by adding water H2O to the fuel gas and / or a precursor of the fuel gas and / or a component of the fuel gas.

5. Method according to one of claims 1 to 4, characterized in that the top gas intended for use as a component of the fuel gas is at least partially dry-dedusted.

6. Device (1) for reducing metal oxide-containing material (2), comprising: - a reduction reactor (3), - a top gas discharge (5) for the discharge of top gas from the reduction reactor (3), - a preparation plant (7) comprising at least one gas burner (6) for the preparation of reducing gas, - a supply line (8) for supplying a subset of the top gas as a fuel gas component to the at least one gas burner (6), characterized in that it also comprises - at least one member of the group consisting of the two members a) at least one device (9) for determining the water vapor content in the reducing gas and / or in the top gas, and b) device (9a) for detecting an increase in the proportion of hydrogen in the reducing gas and / or in the top gas, - a device (10) for controlling and / or regulating the water vapor content in the fuel gas, taking into account the hydrogen content in the reducing gas and / or in the top gas.

7. Device according to claim 6, characterized in that the device (10) for controlling and / or regulating the water vapor content in the fuel gas, including the hydrogen content in the reducing gas and / or in the top gas, comprises at least one gas conditioner.

8. Device according to claim 7, characterized in that the gas conditioner has fuel gas conditioning channels for conditioning top gas provided as a component of the fuel gas with a water supply for fuel gas conditioning, and reduction gas conditioning channels for conditioning top gas provided as a component of the reduction gas with a hot water supply for reduction gas conditioning, wherein the hot water supply for reduction gas conditioning is suitable for supplying hot water for fuel gas conditioning to at least one fuel gas conditioning channel.

9. Device according to one of claims 6 to 8, characterized in that the device for reducing metal oxide-containing material comprises FW supply lines 12a, 12b, 12c which are suitable for introducing liquid water FWf and / or gaseous water FWg into lines which - Fuel gas or - Components of the fuel gas.

10. Device according to one of claims 6 to 9, characterized in that it comprises a dry dust removal device (13) for dry dust removal of top gas, preferably suitable for dry dust removal of at least a subset of the top gas intended for use as a component of the fuel gas.

11. Signal processing device with machine-readable program code, characterized in that it includes control and / or regulation commands for carrying out a method according to the invention. A further object is a signal processing device for carrying out a method according to any one of claims 1 to 5.

12. Machine-readable program code for a signal processing device, characterized in that the program code includes control and / or regulation commands which cause the signal processing device to carry out a method according to one of claims 1 to 5.

13. Storage medium with a machine-readable program code stored thereon according to claim 12.