EP4379069A1 - Hydrogen-based fluidized bed reduction - Google Patents

Abstract

Method for producing a metallized product (20) from metal oxide-containing material (30), comprising fluidized bed reduction of the metal oxide-containing material (30), in which at least a first reducing gas comprising hydrogen and nitrogen is used. In the first reducing gas, the hydrogen content is at least 70 vol.% and the nitrogen content is in a range from 5 vol.% to 30 vol.%, preferably 5 - 20 vol.%.Device (10) for producing a metallized product (20) from metal oxide-containing material (30) using a first reducing gas with a hydrogen content of at least 70 vol.% and a nitrogen content of 5 vol.% to 30 vol.%, comprising a fluidized bed unit (40) with at least two fluidized bed reactors (41,42,43,44), and a reducing gas addition line (50) for adding the first reducing gas to the fluidized bed unit (40).

Description

Field of technology

The application relates to a method for producing a metallized product from metal oxide-containing material, comprising fluidized bed reduction of the metal oxide-containing material, in which at least a first reducing gas comprising hydrogen and nitrogen is used. It also relates to a device for producing a metallized product from metal oxide-containing material using a first reducing gas with a hydrogen content of at least 70 vol% and a nitrogen content of 5 vol% to 30 vol%.

State of the art

It is known to reduce material containing metal oxides, for example iron oxides - such as ores - using reducing gas. For example, by means of direct reduction with reducing gas in a reduction unit, which for example comprises a cascade of fluidized bed reactors for the direct reduction of fine-particle material. To reduce CO2 emissions during the reduction of material containing metal oxides, it is known to use hydrogen H2 as a reducing gas. Hydrogen can be used as the only reducing gas, or in combination with other gases, for example natural gas-based reducing gases. The greater the proportion of CO2-neutral hydrogen H2 in the reducing gas, the less CO2 is emitted.

Reduction of iron oxide-containing material with hydrogen H2 is endothermic. In order to maintain the kinetic and thermodynamic conditions necessary for the economically viable implementation of the reduction reactions, a continuous supply of energy to the reduction unit is therefore necessary. Energy can be supplied via the reducing gas and can be controlled or regulated, for example, via the amount and temperature of the reducing gas supplied. If reducing components of the reducing gas - such as hydrogen H2 - are used as heat carriers in order to introduce the energy required to maintain a desired temperature for endothermic reaction processes into the reduction unit, these components must be provided in quantities that are significantly overstoichiometric with respect to the reduction reactions. Reducing components of the reducing gas provided overstoichiometrically are not consumed during the reduction and can be recirculated after leaving the reduction unit. Provision of reducing components, especially of hydrogen H2, is usually associated with expenditure in terms of costs, energy, and necessary equipment. In order to keep this expenditure to a minimum, efforts are made to avoid providing superstoichiometric amounts of reducing components wherever possible.

The presence of carbon in direct reduced iron (DRI) is desirable because its presence contributes to lowering the melting temperature when melting the DRI, it can have a reducing effect and it can serve as an energy supplier. Carbon is available in reduction processes using carbon- and/or hydrocarbon-containing reducing agents in the reducing gas. Unlike carbon- and/or hydrocarbon-containing reducing agents in the reducing gas, the reducing agent hydrogen H2 does not provide any carbon, which can be contained in the resulting metallized reduction product. This brings with it disadvantages with regard to the processability of the iron directly reduced with this reducing agent.

Summary of the invention Technical task

The aim is to present methods and devices that make it possible to reduce or avoid at least some of the disadvantages mentioned above.

Technical solution

• umfassend Wirbelschichtreduktion des metalloxidhaltigen Materials, bei der zumindest ein erstes Reduktionsgas umfassend Wasserstoff und Stickstoff eingesetzt wird,
• dadurch gekennzeichnet, dass
• im ersten Reduktionsgas
• der Gehalt an Wasserstoff zumindest 70 Vol% beträgt
• und der Gehalt an Stickstoff in einem Bereich von 5 Vol% bis 30 Vol%, bevorzugt 5 - 20 Vol %, liegt.

This object is achieved by a process for producing a metallized product from metal oxide-containing material,

• comprising fluidized bed reduction of the metal oxide-containing material, in which at least a first reducing gas comprising hydrogen and nitrogen is used,
• characterized in that
• in the first reducing gas
• the hydrogen content is at least 70 vol%
• and the nitrogen content is in a range of 5 vol% to 30 vol%, preferably 5 - 20 vol%.

The material containing metal oxide is preferably iron oxide-containing material.

The metal oxide-containing material is reduced by the first reducing gas - and optionally one or more further reducing gases, such as a second reducing gas. In a fluidized bed reduction, the metal oxide-containing material is fluidized by a stream of reducing gas, i.e. kept in a fluidized bed. It is known that good heat exchange takes place between the reducing gas and the metal oxide-containing material, and a large surface is available for reactions to take place between the reducing gas and the metal oxide-containing material. There can be a fluidized bed, which may have several zones, or there can be several fluidized beds connected in parallel or sequentially - for example in a cascade of fluidized bed reactors.

The metallized product has a degree of metallization which is higher than the degree of metallization of the metal oxide-containing material. The metallized product can be the reduction product of the fluidized bed reduction - if the process only comprises fluidized bed reduction - or it can be obtained by a further treatment of the reduction product of the fluidized bed reduction which may be additionally carried out in the process for producing a metallized product.

Advantageous effects of the invention

The first reducing gas comprises or contains at least hydrogen H2 and nitrogen N2; if these are the only components of the first reducing gas, it consists of hydrogen H2 and nitrogen N2. The hydrogen H2 content is at least 70 vol%. Hydrogen H2 serves as the reducing component of the first reducing gas. Hydrogen H2 can be the only reducing component of the first reducing gas, or other reducing components can be present in the first reducing gas in addition to hydrogen H2; for example, supplied from reforming of natural gas such as steam reforming or CO2 reforming.

The nitrogen N2 content is at least 5 vol% and up to 30 vol%, preferably up to 20 vol%. One function of nitrogen is to transport heat into the fluidized bed; heat transported by it into the fluidized bed does not have to be introduced into the fluidized bed by reducing components of the first reducing gas. The more nitrogen there is, the fewer reducing components of the first reducing gas have to be provided in excess of stoichiometric amounts for heat transport. With a nitrogen content of more than 30 vol%, however, the reducing power of the first reducing gas would be too limited by the high proportion of nitrogen, which is inert with regard to the reduction of the metal oxide-containing material.

The nitrogen content in the first reducing gas should be at least 5 vol% so that the effect as a heat carrier or the reduction of the need to provide reducing components of the first reducing gas in superstoichiometric quantities is sufficiently pronounced.

In addition to hydrogen H2 and nitrogen N2, other components may also be present in the first reducing gas, such as water H2O, carbon monoxide CO, carbon dioxide CO2, and higher hydrocarbons.

The quality of the reduction gas can be changed by the nitrogen N2 content in the first reduction gas. When using a cascade of several fluidized beds in fluidized bed reduction, the quality of the reduction gas and the temperature in different fluidized beds and thus the reduction rate can be changed by the nitrogen content, and the location of the reduction in the reduction unit comprising several fluidized bed reactors containing the fluidized beds can be changed.

The reducing gas quality is expressed, for example, as GOD (Gas Oxidation Degree) which is defined as follows:
(H2O+CO2)/(H2O+CO2+H2+CO), i.e. as the ratio of the corresponding sums of concentrations of the individual components in vol% for the components water H2O, carbon dioxide CO2, hydrogen H2, carbon monoxide CO. In addition, the sum of the concentrations of carbon monoxide CO and hydrogen H2 in vol% is an indication of the reducing gas quality of the reducing gas, since these components are required for the reduction.

In the case of iron oxide, the reduction rate describes the removal of oxygen per unit of time, for example in kilograms (kg oxygen per second s). If the mass flow rate of iron is variable, the specific reduction rate can also be used as kg oxygen per kg iron and per s (kg O / (kg Fe * s)).

Compared to hydrogen H2, the increasing proportion of nitrogen N2 in the first reducing gas also enables simpler nozzle design when using gas distribution plates with nozzles to create a fluidized bed due to its higher molecular weight, higher density and higher viscosity.

By adjusting the proportion of nitrogen N2 in the first reducing gas, the fluidization properties of the fluidized bed can also be changed - for example, smaller bubble size and higher expansion of the fluidized bed with an increasing proportion of nitrogen N2 compared to hydrogen due to its higher density and viscosity compared to hydrogen.

To create a fluidized bed, the first reducing gas must be under pressure and must therefore be compressed; an increasing proportion of nitrogen N2 in the first reducing gas compared to hydrogen H2 can have advantages during compression due to its higher molecular weight, for example when using radial compressors for compression.

The metallized product of the process according to the invention - for example the reduction product of the fluidized bed reduction - has a metallization of at least 80%, preferably at least 85%. It can serve as a basis for the production of steel in subsequent processing steps.

• Fe met: metallisches Eisen in einer Probe (Massenprozent m%)
• Fe tot: insgesamt in der Probe enthaltenes Eisen (Massenprozent m%)

The metallization - also called metallization degree MG - which is given in %, results from the ratio of metallic iron Fe met to
total iron Fe tot present in a sample after $$\mathrm{MG}\left[\%\right]=\mathrm{Fe}\mathrm{met}/\mathrm{Fe}\mathrm{<figure-callout\; id="100"\; label="dead\; *"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">dead</figure-callout>}*100.$$

• Fe met: metallic iron in a sample (mass percent m%)
• Fe tot: total iron contained in the sample (mass percent m%)

When preparing the first reducing gas, a mixture of gases containing components of the first reducing gas is subjected to heating. The heating can take place in several steps, whereby the type of heating used in the various steps can differ from one another. The heated mixture can be fed to the fluidized bed of the fluidized bed reduction, whereby further components can optionally be added in order to set the desired composition for the first reducing gas. A gas mixture entering the fluidized bed has a certain temperature, a certain pressure and a certain composition; it has a reducing effect in the fluidized bed and is the first reducing gas. Before this temperature, pressure and composition are present, the gas mixture is referred to in this application as the reducing gas precursor of the first reducing gas.

If heating of a reducing gas precursor of the first reducing gas takes place before entering the fluidized bed, this is preferably done at least partially by means of electrical heating. Electrical heating can be, for example, resistance heating or heating by means of a plasma produced using electrical energy. Compared to heating using a reducing gas furnace with a burner, electrical heating has the advantage that no exhaust gases are produced and less energy is lost. In a reducing gas furnace with a burner, indirect heat exchange takes place between the flue gas from the combustion carried out with the burner and the reducing gas precursor.

Optionally, in addition to electrical heating, another type of heating or several other types of heating can be used; for example, heating with an indirect heat exchanger - preferably from waste heat from the top gas of the fluidized bed reduction -, heating using a reducing gas furnace with burner, heating by partial oxidation with oxygen or combinations of two or more of these. One burner or several burners can be used in a reducing gas furnace.

Gas with calorific value generated during fluidized bed reduction can be used for energy purposes, which improves the energy efficiency of the process.

Heating of a reducing gas precursor of the first reducing gas can also be carried out without electrical heating by another type of heating; for example, heating with an indirect heat exchanger from waste heat of the top gas of the fluidized bed reduction, heating by means of a reducing gas furnace with burner, heating by partial oxidation with oxygen or combinations of two or more thereof.

A gas stream of reducing gas is introduced into the fluidized bed(s) and flows through the fluidized bed(s), where it is partially consumed as a result of the performance of reduction work. Used reducing gas is discharged; it is also called top gas. Reducing gas used during fluidized bed reduction - i.e. top gas - is used up in the sense of a reduction in the reduction potential. Used reducing gas has a lower reduction potential than fresh reducing gas because at least some of the originally present reducing components have been used up, but it can still have a reduction potential if it still contains reducing components. The top gas still contains reducing components - for example when using the first reducing gas, hydrogen H2 - so recirculation of top gas or use of top gas to prepare the first reducing gas is sensible. During recirculation, treatment steps can take place, such as dedusting the top gas - wet or dry -, compression, heat exchange. The top gas also contains nitrogen N2. In order to avoid an enrichment of nitrogen in the first reducing gas as a result of recirculation, a portion of the top gas is discharged from the recirculation circuit. Since the top gas also contains reducing components, it also has a calorific value.

If heating is carried out using a reducing gas furnace with a burner, it is preferable to use top gas discharged from the recirculation circuit as fuel. The calorific value of the discharged top gas can be used energetically in the process, which improves the energy efficiency of the process. Burners can also be operated with other fuels, or with mixtures of other fuels and discharged top gas.

If heating is carried out both by means of electrical heating and by means of a reducing gas furnace with burner, the electrical heating can, for example, take place before heating by means of a reducing gas furnace with burner and/or afterwards. It is preferable to carry out electrical heating after heating by means of a reducing gas furnace with burner. This allows the use of less temperature-resistant materials for the reducing gas furnace and leads to less energy loss in the exhaust gas of the reducing gas furnace.

According to one embodiment of the method according to the invention, a reducing gas precursor of the first reducing gas is heated at least partially by means of heat exchange with top gas. The heat content of the discharged top gas can be used energetically in the process, which improves the energy efficiency of the process. In addition to heating by means of heat exchange with top gas, other types of heating can also be used, for example the types of electrical heating mentioned above and heating by means of a reducing gas furnace with burner, heating by partial oxidation.

From the group consisting of the above-mentioned types of heating of a reducing gas precursor and electrical heating, individual group members or combinations of two or more group members can be used to heat a reducing gas precursor. If combinations of two or more group members are used, these can be arranged in any sequence. It is preferable to arrange them according to the most economically and technologically sensible temperature range. Preferably, heating can begin with an indirect heat exchanger from waste heat of the top gas of the fluidized bed reduction, followed by electrical heating, followed by heating using a reducing gas furnace with burner, followed by direct heating of the fuel gas using partial oxidation. Depending on the concept of electrical heating, it may be useful to swap the order of electrical heating and reducing gas furnace.

It is preferred that heating of a reducing gas precursor of the first reducing gas is carried out by indirect heat exchange with top gas before electrical heating or heating by means of a reducing gas furnace with burner is carried out.

According to one embodiment of the method according to the invention, the first reducing gas comprises at least one hydrocarbon-containing gas. When preparing the first reducing gas, hydrocarbon-containing gas - for example methane, natural gas, higher hydrocarbons - is then mixed with hydrogen H2 and nitrogen N2. One hydrocarbon-containing gas or several hydrocarbon-containing gases can be used. The proportion of hydrocarbon-containing gas in the first reducing gas can be up to 25 vol%, preferably up to 15 vol%.

When preparing the first reducing gas, the addition of hydrocarbon-containing gas can be carried out, for example, before heating a reducing gas precursor of the first reducing gas. It can also be carried out after heating a reducing gas precursor of the first reducing gas.

On the one hand, the hydrocarbon-containing gas enables the introduction of carbon into the reduction product - metallized by the fluidized bed reduction. On the other hand, it can be used to transport heat into the fluidized bed; thus, it can help to reduce the amount of nitrogen required for a certain amount of heat to be introduced by a gas other than hydrogen. It therefore makes it easier to set a certain nitrogen content and helps to counteract an enrichment of nitrogen during recirculation.

The fluidized bed reduction of the process according to the invention is carried out in at least one fluidized bed and produces a reduction product that is metallized. According to one embodiment of the process according to the invention, hydrocarbon-containing gas is added to at least one fluidized bed of the fluidized bed reduction, preferably to the fluidized bed from which the reduction product of the fluidized bed reduction is taken as a metallized product. The hydrocarbon-containing gas is preferably added in an amount of substance that corresponds to up to 25 mol%, preferably at least up to 15 mol% of the first reduction gas.

According to one embodiment of the process according to the invention for producing a metallized product from metal oxide-containing material, it is carried out in at least two fluidized beds. In the course of the process, the metal oxide-containing material or, if applicable, the reduction product passes through these one after the other.

According to one embodiment of the method according to the invention for producing a metallized product from material containing metal oxide, it also includes adding at least one treatment gas to a fluidized bed. This can be a fluidized bed in which fluidized bed reduction takes place and/or to a fluidized bed in which no fluidized bed reduction takes place - because, for example, all of the particulate material introduced into the fluidized bed has already been reduced, i.e. is a reduction product. The fluidized bed into which treatment gas is added is therefore a fluidized bed made of fluidized particles of material containing metal oxide and/or of fluidized particles of reduction product. The treatment gas has no oxidizing capacity; it has a reducing effect on material containing metal oxide - preferably material containing iron oxide - and contributes to setting a reducing atmosphere in the fluidized bed. If the particulate material introduced into a fluidized bed supplied with treatment gas is still partially is oxidized, it can be reduced by the treatment gas, then fluidized bed reduction takes place in this fluidized bed, and the treatment gas is also another reducing gas, for example a second reducing gas. Preferably only the treatment gas is used to produce the fluidized bed by fluidizing particles, but other gases can also be used to contribute to the fluidization.

For the purposes of this application, the first reducing gas is not to be classified as a treatment gas; the first reducing gas and the treatment gas are different gases.

A treatment gas entering a fluidized bed has a certain temperature, a certain pressure and a certain composition. Before this temperature, pressure and composition are present, a gas or a gas mixture that is a basis for producing the treatment gas is a precursor of the treatment gas.

• erstes Reduktionsgas,
• Behandlungsgas,

erfolgt. Dann wird also in keine Wirbelschicht sowohl erstes Reduktionsgas als auch Behandlungsgas zugegeben.The first reducing gas is added to at least one fluidized bed, and treatment gas is added to at least one fluidized bed. It is preferred if only one gas from the group consisting of

• first reducing gas,
• Treatment gas,

Then neither the first reduction gas nor the treatment gas is added to any fluidized bed.

Preferably, at least one fluidized bed into which treatment gas is added is arranged after the fluidized bed or beds into which first reducing gas is added, as seen in the flow direction of the metal oxide-containing material as it passes through the fluidized beds in the course of the process.

The treatment gas comprises at least one hydrocarbon-containing gas with a proportion of at least 50 vol%. The hydrocarbon-containing gas can be, for example, methane CH4 or a higher hydrocarbon or several higher hydrocarbons, or mixtures thereof; it can also be natural gas. The metallized product of the process according to the invention is preferably taken from a fluidized bed into which treatment gas has been added. Such a metallized product contains carbon, preferably as cementite Fe3C in addition to dissolved carbon. The treatment gas contributes to carburization; the fluidized bed into which it is introduced is also referred to as the carburizing fluidized bed in the context of this application. The top gas emerging from the carburizing fluidized bed is referred to as the carburizing top gas in the context of this application.

Advantageously, carburizing top gas is taken from at least one carburizing fluidized bed and at least partially recirculated via a recirculation circuit into this carburizing fluidized bed and/or into another carburizing fluidized bed, wherein Combination with fresh gas containing hydrocarbons - i.e. gas that has not yet been used in a carburizing fluidized bed - such as methane CH4, higher hydrocarbons, natural gas - takes place. Treatment steps can also take place in the recirculation circuit, such as dedusting the carburizing top gas - wet or dry -, compression, heat exchange to heat another medium - for example the treatment gas, the first reducing gas, water or steam to generate steam or superheated steam -, heating of the recirculated gas stream.

For heating, it is preferable to carry out a two-stage heating process, with a first stage of convective heating up to a maximum temperature of 450°C and a second stage of heating to a temperature above 700°C using resistance heating or plasma burners or self-combustion after oxygen injection. In this way, the critical temperature window of 450 - 700°C with regard to carbon deposition from carbon-rich gases and metal dusting is passed through more quickly than if convective heating were used to heat above 450°C. To avoid carbon deposition and metal dusting, water H2O can also be introduced into the gas circuit. This can be done before or after heating, or between the two stages; it is preferably done before heating.

According to one variant, a partial flow of the carburizing top gas - if necessary after one or more treatment steps - is used to prepare the first reducing gas.

According to one variant, a portion of the carburizing top gas - if necessary after one or more treatment steps - is used as fuel to heat a reducing gas precursor of the first reducing gas using a reducing gas furnace with a burner. The calorific value of the carburizing top gas can be used energetically in the process, which improves the energy efficiency of the process.

The metallized product of the process according to the invention can be added to an EAF or a melting unit for further processing, for example to produce steel based on the metallized product. For this purpose, it is either fed in fine form directly or via an intermediate compaction unit.

According to one variant, the compaction step is completely isolated from the environment and air supply. According to another variant, the compaction step has a gas circuit that consists only of inert gas components such as nitrogen N2.

According to one embodiment, oxygen is injected into the last fluidized bed reactor as seen in the gas flow direction and/or into the reducing gas supplied to the last fluidized bed reactor as seen in the gas flow direction in order to reduce or prevent magnetite formation in this fluidized bed reactor. Alternatively, water can also be injected.

According to one embodiment, the reducing gas quality of the first reducing gas and/or the treatment gas is adjusted by adding water or water vapor to a reducing gas precursor of the first reducing gas and/or a precursor of the treatment gas. It is preferred to add water vapor to heated reducing gas precursors.

Steam for addition can be generated, for example, by indirect heat exchange with a hot gas stream present in the process. This can be, for example, carburizing top gas.

Heat content of carburizing top gas can also be used for other purposes in the process, for example to heat a precursor of the treatment gas.

The top gas of the fluidized bed reduction and/or the carburizing top gas is dedusted. This is preferably done by dry dedusting. However, it can also be done by wet dedusting.

• Differenzdruck über einen Düsenboden einer Wirbelschicht,
• Differenzdruck über eine Wirbelschicht,
• Eindringtiefe der Strahlen von Reduktionsgas in eine Wirbelschicht,
• Gasblasengröße in der Wirbelschicht,

eingestellt.According to one embodiment, the gas composition and/or the pressure for the first reducing gas and/or the treatment gas are determined according to a setpoint value for at least one member of the group consisting of

• Differential pressure across a nozzle bottom of a fluidized bed,
• Differential pressure across a fluidized bed,
• Penetration depth of the jets of reducing gas into a fluidized bed,
• Gas bubble size in the fluidized bed,

set.

• umfassend
• ein Wirbelschichtaggregat mit zumindest zwei Wirbelschichtreaktoren,
• eine Reduktionsgaszugabeleitung zur Zugabe des ersten Reduktionsgases in das Wirbelschichtaggregat.

A further subject matter of the present application is a device for producing a metallized product from metal oxide-containing material using a first reducing gas with a hydrogen content of at least 70 vol% and a nitrogen content of 5 vol% to 30 vol%,

• full
• a fluidized bed unit with at least two fluidized bed reactors,
• a reducing gas addition line for adding the first reducing gas into the fluidized bed unit.

The device also comprises a material feed device for feeding metal oxide-containing material into the fluidized bed unit, as well as a material removal device for removing metallized product from the fluidized bed unit. The device also comprises a top gas discharge line for discharging top gas from the fluidized bed unit. If necessary, a top gas recirculation line is also present, which serves to feed top gas to the reducing gas addition line and optionally has treatment devices such as for example compressors, dust removal devices - for example for dry dust removal or wet dust removal -, heat exchangers. The top gas recirculation line has an outlet branch through which a portion of the top gas can be discharged from the recirculation circuit if required.

The reducing gas addition line is used to guide reducing gas precursors of the first reducing gas or to guide the first reducing gas, and opens into the fluidized bed unit. Addition lines for adding hydrogen and/or adding lines for adding nitrogen can open into the reducing gas addition line; addition lines for adding other components of the first reducing gas can also open into the reducing gas addition line, such as top gas recirculation line, carburizing top gas line.

The at least two fluidized bed reactors are connected in series with respect to the flow of the metal oxide-containing material. According to one embodiment, they are also connected in series with respect to the gas flow, wherein the gas flow of the first reducing gas occurs in the opposite direction to the material flow.

Such a device is suitable for carrying out a method according to the invention.

According to a preferred embodiment, the reducing gas supply line has a heating device. This serves to heat a

• Reduktionsgasofen mit Brenner,
• Wärmetauscher;
• Vorrichtung zur Zufuhr von Oxidationsmittel in die Reduktionsgaszugabeleitung. Zufuhr von Oxidationsmittel - beispielsweise Sauerstoff oder sauerstoffhaltiges Gas wie Luft - in die Reduktionsgaszugabeleitung ermöglicht Energiezufuhr durch partielle Oxidation.

Reduction gas precursor of the first reduction gas flowing through the reduction gas addition line. The heating device comprises, for example, a device for electrical heating and/or a device for heating. Devices for heating supply energy without electrical heating; it is, for example, a member of the group:

• Reducing gas furnace with burner,
• heat exchanger;
• Device for supplying oxidizing agent into the reducing gas supply line. Supplying oxidizing agent - for example oxygen or oxygen-containing gas such as air - into the reducing gas supply line enables energy supply through partial oxidation.

The heating device is preferably a device for electrical heating. Electrical heating can be, for example, a resistance heater or heating by a plasma produced using electrical energy. The heating device is particularly preferably a device for electrical heating using plasma.

According to an advantageous embodiment, the heating device has, in addition to a device for electrical heating, one or more devices for heating.

Preferably, a reducing gas furnace with burner is arranged in front of a device for electrical heating, as seen along the reducing gas addition line in the direction of the fluidized bed unit.

Preferably, a heat exchanger is arranged upstream - as seen along the reducing gas addition line in the direction of the fluidized bed unit - of a device for electrical heating and/or upstream of another type of heating device.

If a reducing gas furnace with burner is present, it is preferred if the discharge branch opens into a fuel supply line for the reducing gas furnace.

According to a preferred embodiment, a hydrocarbon addition line is present; this opens into the reducing gas addition line. It serves to add hydrocarbon-containing gas into the reducing gas addition line in order to prepare a hydrocarbon-containing reducing gas precursor of the first reducing gas. Preferably, it opens into the reducing gas addition line upstream of the heating device, as viewed in the direction of the fluidized bed unit.

There may also be several hydrocarbon addition lines.

According to a preferred embodiment, a hydrocarbon feed line is present; this opens into a fluidized bed reactor of the fluidized bed unit. It serves to feed hydrocarbon-containing gas into the fluidized bed reactor. Preferably, it opens into the fluidized bed reactor for fluidized bed reduction, from which the reduction product of the fluidized bed reduction is taken as a metallized product.

There may also be several hydrocarbon feed lines.

According to a preferred embodiment, a treatment gas addition line is present; this opens into a fluidized bed reactor of the fluidized bed unit. It serves to add treatment gas to the fluidized bed reactor.

There may also be several treatment gas addition lines.

According to a preferred embodiment, at least one carburizing stop gas line is present; such a line starts from a fluidized bed reactor with a treatment gas addition line. It preferably opens into the treatment gas addition line.

According to a preferred embodiment, the carburizing stop gas line also opens into the reducing gas addition line.

According to a preferred embodiment, the carburizing stop gas line also opens into a fuel supply line of a reducing gas furnace with burner.

• Differenzdruck über einen Düsenboden einer Wirbelschicht,
• Differenzdruck über eine Wirbelschicht,
• Eindringtiefe der Strahlen von Reduktionsgas in eine Wirbelschicht,
• Gasblasengröße in der Wirbelschicht,

für das erste Reduktionsgas und/oder das Behandlungsgas.According to a preferred embodiment, the system according to the invention also comprises a device for adjusting the pressure and/or the gas composition according to a setpoint value for at least one member of the group consisting of

• Differential pressure across a nozzle bottom of a fluidized bed,
• Differential pressure across a fluidized bed,
• Penetration depth of the jets of reducing gas into a fluidized bed,
• Gas bubble size in the fluidized bed,

for the first reducing gas and/or the treatment gas.

A further subject of the present application is a signal processing device with a machine-readable program code, characterized in that it has control and/or regulating commands for carrying out a method according to the invention. A further subject is a signal processing device for carrying out a method according to one of claims 1 to 8. The signal processing device is part of a control and/or regulating system of a device for producing a metallized product from metal oxide-containing material.

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 producing a metallized product from material containing metal oxide -, characterized in that the program code has control and/or regulation 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 producing a metallized product from material containing metal oxide - which, when the program for the signal processing device is executed, cause it to carry out the method according to one of claims 1 to 8.

A further subject matter of the present application is a storage medium with a machine-readable program code according to the invention stored thereon. A further subject matter is a storage medium with a computer program stored thereon for carrying out a method according to one of claims 1 to 8.

A further subject matter of the present application is a control and/or regulation of a device for producing a metallized product from metal oxide-containing material with a computer containing a computer program product comprising instructions which, when the computer program is executed by the computer, cause the computer to carry out the steps of a method according to one of claims 1 to 8.

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 8. A further subject matter of the present application is a computer-readable data carrier on which such a computer program product is stored.

Short description of the drawings

• Fig 1 bis 6 Ausführungsformen einer erfindungsgemäßen Vorrichtung, in der Varianten des erfindungsgemäßen Verfahrens durchgeführt werden.
• Fig 7 ein Beispiel für die Herkunft des Reduktionsgasvorläufers des ersten Reduktionsgases.

The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of embodiments, which are explained in more detail in connection with the schematic and exemplary drawings, in which:

• Figs 1 to 6 Embodiments of a device according to the invention in which variants of the method according to the invention are carried out.
• Fig. 7 an example of the origin of the reducing gas precursor of the first reducing gas.

Description of the embodiments Examples

Figure 1 shows a device 10 for producing a metallized product 20 from metal oxide-containing material 30 using a first reducing gas. It comprises a fluidized bed unit 40 with four fluidized bed reactors 41, 42, 43, 44 and a reducing gas addition line 50 for adding the first reducing gas to the fluidized bed unit 40.

The four fluidized bed reactors 41, 42, 43, 44 are connected in series as a cascade of fluidized bed reactors with respect to the flow of the metal oxide-containing material 30. They are also connected in series with respect to the gas flow, with the gas flow of the first reducing gas occurring in the opposite direction to the material flow.

The device 10 also comprises a material feed device 60 for feeding metal oxide-containing material 30 into the fluidized bed unit 40, as well as a material removal device 70 for removing metallized product 20 from the Fluidized bed unit 40. The device also includes a top gas outlet 80 for discharging top gas from the fluidized bed unit 40. Also shown is an optional top gas recirculation line 90 for supplying top gas to the reducing gas addition line 50. In the variant shown, this has treatment devices such as compressor 100 and dedusting device 110 - for example for wet dedusting. The top gas recirculation line 90 has a discharge branch 120 through which a portion of the top gas can be discharged from the recirculation circuit if required.

The reducing gas addition line 50 opens into the fluidized bed unit 40. An addition line 130 for adding hydrogen and an addition line 140 for adding nitrogen open into the reducing gas addition line 50. A branch of the top gas recirculation line 90 also opens into the reducing gas addition line, so that top gas can be recirculated into the reducing gas circuit.

The device 10 is used to carry out a method for producing a metallized product 20 from metal oxide-containing material 30. For this purpose, fluidized bed reduction of the metal oxide-containing material 30 takes place in the fluidized bed reactors 41, 42, 43, 44 using the first reducing gas. The first reducing gas comprises hydrogen and nitrogen, the hydrogen content being at least 70 vol% and the nitrogen content being in a range from 5 vol% to 30 vol%.

Shown is an optional heating of a mixture of gases containing components of the first reducing gas in the optionally present heating device during the preparation of the first reducing gas.

In the variant shown, the heating device is a reducing gas furnace with burner 150, which can be supplied with top gas as fuel from the top gas recirculation line 90 via the discharge branch 160 that opens into a fuel supply line for the reducing gas furnace. Other fuels can also be used, these are supplied via corresponding addition lines; only one such addition line 170 is shown as an example. The oxidizing agent - for example oxygen or oxygen-containing gas such as air - can be supplied via an optionally available oxidizing agent line 171.

Instead of the reducing gas furnace 150 with burner, the heating device could also be a device for electrical heating, which is not separately shown; this could operate without the supply of oxidizing agent or fuel.

Figure 2 shows largely analogous to Figure 1 , such as heating a reducing gas precursor of the first reducing gas before entering the fluidized bed partly by means of electrical Heating takes place in a device for electrical heating 180. In the variant shown, the electrical heating takes place in the gas flow direction after the reducing gas furnace 150 of the heating device.

Figure 3 shows largely analogous to Figure 2 , such as heating of a reducing gas precursor of the first reducing gas, which is carried out at least partially by means of heat exchange with top gas. Heating of a reducing gas precursor of the first reducing gas is carried out by indirect heat exchange with top gas before electrical heating or heating by means of a reducing gas furnace 150 with burner is carried out. A heat exchanger 190a is installed in front of the device for electrical heating 180 and the reducing gas furnace 150 with burner, as seen along the reducing gas addition line 50 in the direction of the fluidized bed unit.

In the example shown, it transfers heat from the top gas to the reducing gas precursor of the first reducing gas via the heat exchanger 190b.

Figure 4 shows in to Figure 3 In a largely analogous representation, two variants of how hydrocarbon-containing gas can be introduced into the fluidized bed reduction. Both variants can be implemented individually or together. According to one variant, a hydrocarbon addition line 200 - for example for the addition of natural gas - flows into the reduction gas addition line 50, in the example shown before heating steps.

According to another variant, a hydrocarbon feed line 210 - for example for feeding in natural gas - flows into a fluidized bed reactor of the fluidized bed unit; the opening into the fluidized bed reactor 44 for fluidized bed reduction is shown, from which the reduction product of the fluidized bed reduction is taken as a metallized product 20.

Figure 5 shows a variant of a device 220 for producing a metallized product 20 from metal oxide-containing material 30 using a first reducing gas. It comprises a fluidized bed unit 230 with four fluidized bed reactors 231, 232, 233, 240 and a reducing gas addition line 250 for adding the first reducing gas to the fluidized bed reactor 233 of the fluidized bed unit 230.

The four fluidized bed reactors 231, 232, 233, 240 are connected in series as a cascade of fluidized bed reactors with respect to the flow of the metal oxide-containing material 30. They are also connected in series with respect to the gas flow, with the gas flow of the first reducing gas from fluidized bed reactor 233 to fluidized bed reactor 231 taking place in the opposite direction to the material flow. The material flow takes place from fluidized bed reactor 231 in the direction of fluidized bed reactor 240.

The device 220 is used to carry out a method for producing a metallized product 20 from metal oxide-containing material 30. For this purpose, using the first Reducing gas fluidized bed reduction of the metal oxide-containing material 30 in the fluidized bed reactors 231,232,233.

A treatment gas addition line 260 opens into the fluidized bed reactor 240 of the fluidized bed unit 230. It serves to add treatment gas to the fluidized bed reactor 240. In the variant shown, the fluidized bed reactor 240 contains a fluidized bed of fluidized particles of reduction product of the fluidized bed reduction that took place by means of the first reduction gas in the fluidized bed reactors 231, 232, 233. The treatment gas comprises at least one hydrocarbon-containing gas with a proportion of at least 50 vol%.

In the variant shown, the metallized product of the process according to the invention is taken from the fluidized bed of the fluidized bed reactor 240. This fluidized bed is a carburizing fluidized bed.

In the variant shown, a carburizing top gas line 270 extends from the fluidized bed reactor 240 and opens into the treatment gas addition line 260. Carburizing top gas is taken from the carburizing fluidized bed in the fluidized bed reactor 240 via this line and is at least partially recirculated into this carburizing fluidized bed via a recirculation circuit via its recirculation gas inlet section 280, combining with fresh hydrocarbon-containing gas - in the case shown, natural gas - which is provided via the natural gas supply line 290.

The recirculation circuit also shows the optional treatment steps of dedusting the carburizing top gas in the deduster 300 and compression in the compressor 310, heating the recirculated gas flow in the gas heater 320. The deduster 300 can be a device for wet dedusting or a device for dry dedusting. If it is a device for dry dedusting, a heat exchanger can optionally be present in front of it for the purpose of cooling the carburizing top gas before dry dedusting.

In the illustrated embodiment, a branch of the carburizing top gas line 270 also opens into the reducing gas addition line 250, which enables use of a partial flow of the carburizing top gas to prepare the first reducing gas.

Figure 6 shows largely analogous to the Figures 1 and 5 , such as carburizing top gas in addition to the Figure 5 shown use can also be used as fuel for a reduction gas furnace 330 with burner. For this purpose, a branch of the carburizing gas line 270 - shown is a branch of this branch from its section recirculation line 280 - flows into a fuel supply line for the reduction gas furnace 330 with burner.

Also in Figure 6 Shown are optionally available water addition lines 340,341,342 for adding water and/or water vapor into reducing gas precursors of the first reducing gas or into precursors of the treatment gas.

Figure 7 shows an example of the origin of a reducing gas precursor of the first reducing gas using an excerpt from Figures 1 to 4 . A reducing gas precursor is provided via a precursor feed line 350 and mixed with gas from the recirculation circuit via the top gas recirculation line 90. During the preparation of the first reducing gas, hydrogen and nitrogen are subsequently added via the addition lines 130 and 140. In a steam reformer 360, a gas mixture is produced from natural gas 370 with steam 380, the carbon dioxide CO2 content of which is reduced in a CO2 separation device 390. The gas mixture obtained in this way is provided as a reducing gas precursor of the first reducing gas via the precursor feed line 350.

In principle, a reducing gas precursor of the first reducing gas, supplied analogously via a precursor feed line 350, can also come from other sources

Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited to the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

List of reference symbols

10

Device for producing a metallized product

20

Metallized product

30

Material containing metal oxide

40

Fluidized bed unit

41

Fluidized bed reactor

42

Fluidized bed reactor

43

Fluidized bed reactor

44

Fluidized bed reactor

50

Reducing gas addition line

60

Material feed device

70

Material removal device

80

Top gas discharge

90

Top gas recirculation line

100

compressor

110

Dust extraction device

120

Discharge branch

130

Addition line for adding hydrogen

140

Addition line for adding nitrogen

150

Reducing gas furnace with burner

160

Discharge branch

170

Train derivation

171

Oxidant line

180

Device for electrical heating

190a

Heat exchanger

190b

Heat exchanger

200

Hydrocarbon addition line

210

Hydrocarbon feed line

220

Device for producing a metallized product

230

Fluidized bed unit

231

Fluidized bed reactor

232

Fluidized bed reactor

233

Fluidized bed reactor

240

Fluidized bed reactor

250

Reducing gas addition line

260

Treatment gas addition line

270

Carburizing stop gas line

280

Recirculation gas introduction

290

Natural gas supply

300

Dust collector

310

compressor

320

Gas heater

330

Reducing gas furnace with burner

340

Water addition line

341

Water addition line

342

Water addition line

350

Precursor supply line

360

Steam reformer

370

natural gas

380

steam

390

CO2 separation device

Claims (15)

Process for producing a metallized product (20) from metal oxide-containing material (30), comprising fluidized bed reduction of the metal oxide-containing material (30), in which at least a first reducing gas comprising hydrogen and nitrogen is used, characterized in that in the first reducing gas the hydrogen content is at least 70 vol% and the nitrogen content is in a range of 5 vol% to 30 vol%, preferably 5 - 20 vol%. Method according to claim 1, wherein the first reducing gas enters a fluidized bed and heating of a reducing gas precursor of the first reducing gas takes place before entering the fluidized bed, characterized in that the heating takes place at least partially by means of electrical heating. Method according to claim 2, characterized in that in addition to the electrical heating, another type or several other types of heating are used, preferably at least one member from the group consisting of the members: - Heating with indirect heat exchanger (190a, 190b), - Heating by means of a reducing gas furnace (150) with burner, - Heating by partial oxidation with oxygen. Method according to claim 3, wherein reducing gas consumed in the fluidized bed reduction is discharged as top gas and is at least partially recirculated in a recirculation circuit, wherein a portion of the recirculated top gas is discharged from the recirculation circuit, characterized in that top gas discharged from the recirculation circuit is used as fuel for the burner. Method according to one of claims 1 to 4, characterized in that the first reducing gas comprises at least one hydrocarbon-containing gas. Method according to one of claims 1 to 5, wherein the fluidized bed reduction is carried out in one fluidized bed or several fluidized beds, characterized in that hydrocarbon-containing gas is added to at least one fluidized bed of the fluidized bed reduction, preferably to the fluidized bed from which the reduction product of the fluidized bed reduction is taken as a metallized product (20). Process according to one of claims 1 to 6, characterized in that it is carried out in at least two fluidized beds. Method according to one of claims 1 to 7, characterized in that it also comprises adding at least one treatment gas into at least one fluidized bed. Device (10) for producing a metallized product (20) from metal oxide-containing material (30) using a first reducing gas with a hydrogen content of at least 70 vol% and a nitrogen content of 5 vol% to 30 vol%, full a fluidized bed unit (40) with at least two fluidized bed reactors (41,42,43,44), a reducing gas addition line (50) for adding the first reducing gas into the fluidized bed unit (40). Device according to claim 9, characterized in that the reducing gas addition line (50) has a heating device. Device according to claim 10, characterized in that the heating device in addition to a device for electrical heating (180) also has one or more devices for heating. Device according to one of claims 9 to 11, characterized in that a hydrocarbon addition line (200) is present which opens into the reducing gas addition line (50). Device according to one of claims 9 to 12, characterized in that a hydrocarbon feed line (210) is present which opens into a fluidized bed reactor (44) of the fluidized bed unit (40). Device according to one of claims 9 to 13, characterized in that a treatment gas addition line (260) is present which opens into a fluidized bed reactor (240) of the fluidized bed unit (230). Device according to one of claims 9 to 14, characterized in that at least one carburizing stop gas line (270) is present, which starts from a fluidized bed reactor (240) with a treatment gas addition line (260); preferably it opens into the treatment gas addition line (260).

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