Method and equipment for the continuous production of sponge iron from iron ore

Abstract

An installation for producing sponge iron, comprising a direct reduction shaft (1), a device (2) for charging iron ore into the direct reduction shaft (1), a device (3) for extracting sponge iron from the direct reduction shaft (1), a hydrogen-rich reducing gas source (4), a reducing gas line (5) extending from the hydrogen-rich reducing gas source (4) to the direct reduction shaft (1), and a heater (6) for heating the hydrogen-rich reducing gas in the reducing gas line (5). The installation includes a flow meter (7) configured to measure a flow rate of the hydrogen-rich reducing gas in the reducing gas line (5), and a control unit (8) configured to control the device (2) for charging iron ore into the direct reduction shaft (1) and to control the device (3) for extracting sponge iron from the direct reduction shaft (1) based on an input from the flow meter (7), such that the flow rate of the iron ore and the flow rate of the sponge iron are proportional to the measured flow rate of the hydrogen-rich reducing gas.

Description

[Technical field]

[0001] The present invention relates to a continuous production of sponge iron from iron ore, comprising the steps of: charging iron ore into a direct reduction shaft; supplying a hydrogen-rich reducing gas; heating the hydrogen-rich reducing gas to a predetermined temperature; introducing the heated hydrogen-rich reducing gas into the direct reduction shaft to reduce the iron ore and produce sponge iron; and extracting the produced sponge iron from the direct reduction shaft.

[0002] The present invention also relates to an installation for producing sponge iron, comprising: a direct reduction shaft; a device for charging iron ore into the direct reduction shaft; a device for extracting sponge iron from the direct reduction shaft; a hydrogen-rich reducing gas source; a reducing gas line extending from the device for supplying hydrogen-rich reducing gas to the direct reduction shaft; and a heater for heating the hydrogen-rich reducing gas. [Background technology]

[0003] The continuous production of sponge iron is known using direct reduction of iron ore in a direct reduction shaft. Hydrogen can therefore be used primarily as the reducing gas, whereby carbon dioxide emissions from the shaft are significantly reduced compared to technologies that use a carbon-containing gas, such as natural gas, as the primary reducing gas.

[0004] Hydrogen gas is usually produced through an electrically driven process in so-called electrolysers. Access to the electricity required for the electrolyser may vary over time and / or the price of available electricity may fluctuate. As a result, the flow rate from the electrolyser to the direct reduction shaft may vary. The prior art proposes the addition of further reducing gas, e.g. natural gas, to the hydrogen gas stream to compensate for the latter fluctuations. However, such compensation leads to increased emissions of carbon dioxide emissions. Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a method and an installation for producing sponge iron by direct reduction of iron ore with a hydrogen-rich reducing gas, which compensates for fluctuations in the flow rate of the hydrogen-rich reducing gas without reducing or increasing carbon dioxide emissions from the direct reduction, as compared to solutions using natural gas for compensation.

[0006] Fluctuations in the flow rate of the hydrogen-rich gas may be due to planned control of the flow rate, for example due to fluctuations in the price of electricity required to generate the hydrogen used in the process, or unintended fluctuations, for example due to fluctuations in the availability of electricity used to generate the hydrogen used in the process. If hydrogen gas is taken from the top gas from the direct reduction shaft and added to the hydrogen gas used as the reducing gas, fluctuations may also be caused by fluctuating conditions in the direct reduction shaft, resulting in fluctuations in the flow rate of hydrogen gas taken from the top gas. The fluctuations may be of considerable magnitude and of considerable duration. [Means for solving the problem]

[0007] The objectives of the present invention are: - charging the iron ore directly into the reduction shaft; - providing a hydrogen-rich reducing gas; - heating the hydrogen-rich reducing gas to a predetermined temperature; - directing the heated hydrogen-rich reducing gas into a direct reduction shaft to reduce the iron ore and produce sponge iron; and - The process of extracting the resulting sponge iron directly from the reduction shaft 1. A method for the continuous production of sponge iron from iron ore, comprising: - measuring the flow rate of the hydrogen-rich gas; and - controlling a flow rate of iron ore to the direct reduction shaft based on the measured flow rate of the hydrogen-rich gas; and - controlling the flow rate of sponge iron extracted from the direct reduction shaft based on the measured flow rate of the hydrogen-rich gas. where the flow rate of the iron ore and the flow rate of the sponge iron are controlled to be proportional to a measured flow rate of the hydrogen-rich reducing gas.

[0008] According to one embodiment, the invention includes the further step of measuring the composition of the hydrogen-rich reducing gas, wherein the flow rate of iron ore to the shaft and the flow rate of sponge iron extracted from the direct reduction shaft are controlled based on the measured flow rate of the hydrogen-rich reducing gas and the measured composition of the hydrogen-rich reducing gas.

[0009] According to one embodiment, the composition of the hydrogen-rich reducing gas is evaluated with respect to the content of reducing agent that will result in direct reduction of the iron ore, where the content of reducing agent and the flow rate of the hydrogen-rich reducing gas are multiplied together to generate an input value based on which the flow rates of the iron ore and sponge iron are controlled.

[0010] According to one embodiment, the flow rates of iron ore and sponge iron are controlled so that they correspond to each other and that the combined level of iron ore and sponge iron in the direct reduction shaft is maintained at a constant level.

[0011] According to one embodiment, the flow rate of the hydrogen-rich reducing gas has a predetermined nominal value applied during predetermined nominal operating conditions of the direct reduction shaft, wherein a predetermined initial decrease in the flow rate of the hydrogen-rich gas from said nominal value to a threshold value is compensated by the addition of methane gas to the hydrogen-rich gas without a corresponding decrease in the flow rates of the iron ore and sponge iron, and the flow rates of the iron ore and sponge iron are controlled based on the measured flow rate of hydrogen gas once the flow rate of the hydrogen-rich gas is further decreased below said threshold value.

[0012] According to one embodiment, the method includes measuring a pressure in a direct reduction shaft, wherein the addition of said methane gas is controlled to maintain a nominal operating pressure in the direct reduction shaft upon a decrease in a flow rate of hydrogen-rich reducing gas from said nominal value to said threshold value.

[0013] According to one embodiment, the hydrogen-rich gas comprises at least 80% by weight hydrogen gas.

[0014] According to one embodiment, the hydrogen-rich gas comprises at least 90% by weight hydrogen gas.

[0015] According to one embodiment, the hydrogen-rich gas comprises at least 95% by weight hydrogen gas.

[0016] According to one embodiment, the hydrogen-rich reducing gas is composed of hydrogen gas produced in the electrolyser and hydrogen gas obtained from the off-gas extracted from the direct reduction shaft.

[0017] According to one embodiment, the step of measuring the flow rate of hydrogen-rich gas comprises measuring the flow rate of hydrogen carried by the off-gas or measuring the flow rate of hydrogen gas obtained from the off-gas. Preferably, the method comprises a step of mixing hydrogen gas from the electrolyser and hydrogen gas obtained from the off-gas, where the measurement is performed upstream of the point of mixing said hydrogen gases as seen in the flow direction of the respective hydrogen gases. The flow rate of hydrogen gas in the off-gas is a good indication whether the reduction has been carried out with a sufficient amount of hydrogen gas to result in sponge iron with a predetermined minimum level of metallization, preferably more than 90% by weight, or even more preferably more than 92.5% by weight of iron. By controlling the flow rate of iron ore to the direct reduction shaft based on the measured flow rate of hydrogen gas in the off-gas or the hydrogen gas obtained from the off-gas, and by controlling the flow rate of sponge iron extracted from the direct reduction shaft based on the measured flow rate of hydrogen gas in the off-gas or the hydrogen gas obtained from the off-gas, the flow rate of hydrogen carried by the off-gas can be controlled within a predetermined range resulting in sponge iron with at least said predetermined minimum level of metallization. The object of the present invention is also to: - Direct reduction shaft, - a device for charging iron ore directly into the reduction shaft; - A device for extracting sponge iron directly from the reduction shaft; - a hydrogen-rich reducing gas source; - a reduction gas line running from a hydrogen-rich reduction gas source directly to the reduction shaft; - A heater for heating the hydrogen-rich reducing gas in the reducing gas line An installation for producing sponge iron, comprising: - a flow meter configured to measure a flow rate of the hydrogen-rich reducing gas in the reducing gas line; - a control unit configured to control a device for charging iron ore into the direct reduction shaft and to control a device for extracting sponge iron from the direct reduction shaft based on an input from the flow meter such that a flow rate of the iron ore and a flow rate of the sponge iron are proportional to a measured flow rate of the hydrogen-rich reducing gas. This is achieved by using an apparatus, characterized in that it includes:

[0018] According to one embodiment, the installation includes a sensor for measuring a composition of the hydrogen-rich reducing gas, wherein the control unit is configured to control a device for charging iron ore into the direct reduction shaft and to control a device for extracting sponge iron from the direct reduction shaft based on an input from said sensor.

[0019] According to one embodiment, the control unit is configured to evaluate the composition of the hydrogen-rich reducing gas with respect to the content of reducing means resulting in the direct reduction of the iron ore, to multiply the content of reducing means and the flow rate of the hydrogen-rich reducing gas together, and to generate input values ​​based thereon, on which the device for charging the iron ore and the device for extracting sponge iron are controlled.

[0020] According to one embodiment, the control unit is configured to control a device for charging iron ore into the direct reduction shaft and a device for extracting sponge iron from the direct reduction shaft such that the flows of iron ore and sponge iron correspond to each other and the combined level of iron ore and sponge iron in the direct reduction shaft is maintained at a constant level.

[0021] According to one embodiment, the installation comprises a methane gas source and a device for controlling a flow of methane gas from said methane gas source to a reducing gas line, wherein the flow rate of the hydrogen-rich reducing gas has a predetermined nominal value applied during predetermined nominal operating conditions of the direct reduction shaft, wherein in response to a predetermined initial measured decrease in the flow rate of the hydrogen-rich gas from said nominal value to a threshold value, the control unit is configured to compensate for said decrease by controlling the addition of methane gas from the methane gas source to the hydrogen-rich reducing gas line, without a corresponding decrease in the flow rates of the iron ore and sponge iron, wherein the control unit is configured to control the flow rates of the iron ore and the sponge iron by controlling the device for charging the iron ore and the device for extracting the sponge iron based on the measured flow rate of the hydrogen-rich reducing gas when the flow rate of the hydrogen-rich reducing gas further decreases below said threshold value.

[0022] According to one embodiment, the installation includes a sensor for measuring the pressure in the direct reduction shaft, wherein the control unit is configured to control the addition of said methane gas upon a decrease in the flow rate of the hydrogen-rich reducing gas from said nominal value to said threshold value such that a nominal operating pressure in the direct reduction shaft is maintained.

[0023] According to one embodiment, the hydrogen-rich reducing gas source includes an off-gas return line for returning the off-gas extracted from the electrolyser and the direct reduction shaft.

[0024] According to some embodiments, the installation further comprises a flow meter configured to measure the flow rate of hydrogen gas in the off-gas return line, where the control unit is configured to control the device for charging iron ore into the direct reduction shaft and to control the device for extracting sponge iron from the direct reduction shaft based on the input from the flow meter. The control unit is configured to control said devices, where the flow rates of iron ore and sponge iron are proportional to the measured flow rate of hydrogen carried by the off-gas. In the disclosed embodiment, the flow meter is located upstream of an off-gas scrubbing facility provided in the off-gas return line. However, the flow meter may also be located downstream of the off-gas scrubbing facility, provided that the efficiency of the off-gas scrubbing facility is considered in terms of what percentage of hydrogen gas can be recovered. The control is performed with respect to previous data taking into account the relationship between the quality of sponge iron, defined mainly by the degree of metallization, and the hydrogen gas content in the off-gas. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic diagram of an installation according to an embodiment of the invention in which a method according to the invention is applied; [Diagram 2] FIG. 2 illustrates a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] In the following detailed description, method embodiments of the present invention are disclosed, as well as equipment configured to carry out the methods.

[0027] The installation for producing sponge iron comprises a direct reduction shaft 1, a device 2 for charging iron ore into the direct reduction shaft 1, a device 3 for extracting sponge iron from the direct reduction shaft 1, a hydrogen-rich reducing gas source 4, 13, a reducing gas line 5 extending from the hydrogen-rich reducing gas source 4, 13 to the direct reduction shaft 1. The hydrogen-rich gas comprises at least 95% by weight of hydrogen gas. A heater 6 for heating the hydrogen-rich reducing gas in the reducing gas line 5 is also provided. According to an embodiment, the heater 6 is an electric heater using an electric resistance element to heat the gas passing through the heater. The direct reduction shaft 1 is a vertical shaft in which the iron ore is charged through an inlet at the top of the shaft and extracted from the bottom of the shaft. The device 2 for charging iron ore comprises a valve device suitable for the purpose and the device 3 for extracting sponge iron comprises a valve device suitable for the purpose. The hydrogen-rich reducing gas supply source includes an off-gas return line 13 for returning the off-gas extracted from the electrolytic cell 4 and the direct reduction shaft 1. The heater 6 is a heater for heating the reducing gas to a temperature in the range of 750 to 1100°C.

[0028] The installation further comprises a flow meter 7 configured to measure the flow rate of the hydrogen-rich reducing gas in the reducing gas line 5, and a control unit 8 configured to control a device 2 for charging iron ore into the direct reduction shaft 1 and to control a device 3 for extracting sponge iron from the direct reduction shaft 1 based on an input from the flow meter 7. The control unit 8 is configured to control said devices 2, 3, such that the flow rates of the iron ore and the sponge iron are proportional to the measured flow rate of the hydrogen-rich reducing gas. The control unit 8 may be any suitable combination of hardware and software for controlling the operation of the installation.

[0029] The installation further comprises a sensor 9 for measuring the composition of the hydrogen-rich reducing gas. The control unit 8 is configured to control the device 2 for charging iron ore into the direct reduction shaft 1 and to control the device 3 for extracting sponge iron from the direct reduction shaft 1 based on an input from said sensor 9. More precisely, the control unit 8 is configured to evaluate the measured composition of the hydrogen-rich reducing gas with respect to a content of reducing means resulting in the direct reduction of the iron ore, to multiply the content of reducing means and the flow rate of the hydrogen-rich reducing gas with each other and to generate an input value on the basis of which the device 2 for charging iron ore and the device 3 for extracting sponge iron are controlled.

[0030] Furthermore, the control unit 8 is configured to control the device 2 for charging iron ore and to control the device 3 for extracting sponge iron such that the flows of iron ore and sponge iron correspond to each other and the combined level of iron ore and sponge iron in the direct reduction shaft 1 is maintained at a constant level.

[0031] The installation comprises a methane gas source 10 and a valve device 11 for controlling the flow of methane gas from said methane gas source 10 to a reducing gas line 5. The flow rate of the hydrogen-rich reducing gas has a predefined nominal value applied during predefined nominal operating conditions of the direct reduction shaft 1, and in response to a predefined initial measured decrease in the flow rate of the hydrogen-rich gas from said nominal value to a threshold value, the control unit 8 is configured such that said decrease is compensated by controlling the addition of methane gas from the methane gas source to the hydrogen-rich reducing gas without a corresponding decrease in the flow rates of the iron ore and sponge iron. The control unit 8 is configured to control the flow rates of the iron ore and sponge iron by controlling the device 2 for charging iron ore and the device 3 for extracting sponge iron based on the measured flow rate of the hydrogen-rich reducing gas when the flow rate of the hydrogen-rich reducing gas further decreases below said threshold value.

[0032] The installation further comprises a sensor 12 for measuring the pressure in the direct reduction shaft 1. The output from the pressure sensor 12 is used as an input to a control unit 8. The control unit 8 is configured to control the addition of said methane gas upon a decrease in the flow rate of hydrogen-rich reducing gas from said nominal value to said threshold value such that the nominal operating pressure in the direct reduction shaft 1 is maintained.

[0033] Needless to say, the installation also comprises further devices well known to those skilled in the art to achieve functions such as pressurization, washing of the off-gas, etc. Thus, the installation also comprises an off-gas washing installation 14 provided in the reduction gas line 5, an off-gas return line 13 and a compressor installation 15. If deemed necessary, further compressor and washing steps may also be provided.

[0034] The facility is thus configured to carry out the method of the invention, which comprises the following steps: - charging the iron ore into a direct reduction shaft 1; - providing a hydrogen-rich reducing gas; - heating the hydrogen-rich reducing gas to a predetermined temperature; - introducing heated hydrogen-rich reducing gas into the direct reduction shaft 1 to reduce the iron ore and produce sponge iron; and - The process of extracting the produced sponge iron from the direct reduction shaft 1 Includes.

[0035] This method is - measuring the flow rate of the hydrogen-rich gas; and - controlling the flow rate of iron ore to the direct reduction shaft 1 based on the measured flow rate of the hydrogen-rich gas; and - controlling the flow rate of the extracted sponge iron from the direct reduction shaft 1 based on the measured flow rate of the hydrogen-rich gas. Further comprising: The iron ore flow rate and the sponge iron flow rate are controlled to be proportional to the measured flow rate of hydrogen-rich reducing gas.

[0036] The method also includes measuring a composition of the hydrogen-rich reducing gas, wherein the flow rate of iron ore to shaft 1 and the flow rate of sponge iron extracted from direct reduction shaft 1 are controlled based on the measured flow rate of the hydrogen-rich reducing gas and the measured composition of the hydrogen-rich reducing gas.

[0037] The composition of the hydrogen-rich reducing gas is evaluated with respect to the content of reducing agent that will result in direct reduction of the iron ore, and the reducing agent content and the hydrogen-rich reducing gas flow rate are multiplied together to generate input values ​​based on which the flow rates of iron ore and sponge iron are controlled.

[0038] The flow rates of iron ore and sponge iron are controlled so that they correspond to each other and that the combined level of iron ore and sponge iron in the direct reduction shaft 1 is maintained at a constant level.

[0039] The flow rate of the hydrogen-rich reducing gas has a predetermined nominal value applied during a predetermined nominal operating condition of the direct reduction shaft 1, where a predetermined initial decrease in the flow rate of the hydrogen-rich gas from said nominal value to a threshold value is compensated by the addition of methane gas to the hydrogen-rich gas without a corresponding decrease in the flow rates of the iron ore and sponge iron, where the flow rates of the iron ore and sponge iron are controlled based on the measured flow rates of hydrogen gas once the flow rate of the hydrogen-rich gas is further decreased below said threshold value. The addition of methane gas is an optional embodiment. As an alternative embodiment, compensation for fluctuations in the flow of the hydrogen-rich reducing gas is performed only by controlling the flow rates of the iron ore entering the shaft and the sponge iron leaving the shaft.

[0040] The method further includes the step of measuring the pressure in the direct reduction shaft 1, wherein the addition of the methane gas is controlled to maintain a nominal operating pressure in the direct reduction shaft 1 upon a decrease in the flow rate of the hydrogen-rich reducing gas from the nominal value to the threshold value.

[0041] The second embodiment disclosed in FIG. 2 differs from the embodiment shown in FIG. 1 in that the step of measuring the flow rate of hydrogen-rich gas comprises measuring the flow rate of hydrogen carried by the off-gas or measuring the flow rate of hydrogen gas obtained from the off-gas. Preferably, the method comprises a step of mixing hydrogen gas from the electrolytic cell and hydrogen gas obtained from the off-gas, where the measurement is performed upstream of the point of mixing said hydrogen gases as seen in the flow direction of the respective hydrogen gases. The flow rate of hydrogen gas in the off-gas is a good indication whether reduction has been performed with a sufficient amount of hydrogen gas to result in sponge iron with a predetermined minimum level of metallization, preferably more than 90% by weight, or even more preferably more than 92.5% by weight of iron. By controlling the flow rate of iron ore to the direct reduction shaft based on the measured flow rate of hydrogen gas in the off-gas or the hydrogen gas obtained from the off-gas, and by controlling the flow rate of sponge iron extracted from the direct reduction shaft based on the measured flow rate of hydrogen gas in the off-gas or the hydrogen gas obtained from the off-gas, the flow rate of hydrogen carried by the off-gas can be controlled within a predetermined range that results in sponge iron with at least said predetermined minimum level of metallization.

[0042] The installation according to Fig. 2 includes a flowmeter 16 configured to measure the flow rate of hydrogen gas in the off-gas return line 13, where the control unit 8 is configured to control the device 2 for charging iron ore into the direct reduction shaft 1 and the device 3 for extracting sponge iron from the direct reduction shaft 1 based on the input from the flowmeter 16. The control unit 8 is configured to control said devices 2, 3, where the flow rates of iron ore and sponge iron are proportional to the measured flow rate of hydrogen carried by the off-gas. In the disclosed embodiment, the flowmeter 16 is arranged upstream of the off-gas scrubbing installation 14. However, the flowmeter 16 may also be arranged downstream of the off-gas scrubbing installation 14, provided that the efficiency of the off-gas scrubbing installation 14 is taken into account in terms of what percentage of hydrogen gas can be recovered.

[0043] The control unit 8 is preferably configured such that the input from the flowmeter 16 in the off-gas return line is prioritized compared to the input from the flowmeter 7 in the reducing gas line 5. The input from the flowmeter in the off-gas return line 13 is therefore decisive for the control of the devices 2, 3, and where the inputs from the different flowmeters result in different indications of the output from the control unit 8, the iron ore flow rate and the sponge iron flow rate are proportional to the measured flow rate of the hydrogen flow carried by the off-gas.

Claims

1. - charging iron ore into a direct reduction shaft (1); - providing a hydrogen-rich reducing gas; - heating a hydrogen-rich reducing gas to a predetermined temperature; - introducing heated hydrogen-rich reducing gas into the direct reduction shaft (1) to reduce the iron ore and produce sponge iron; and - A step (1) of extracting the resulting sponge iron from the direct reduction shaft.

1. A method for the continuous production of sponge iron from iron ore, comprising: - measuring the flow rate of the hydrogen-rich gas; and - controlling the flow rate of iron ore to the direct reduction shaft (1) based on the measured flow rate of hydrogen-rich gas; and - controlling the flow rate of sponge iron extracted from the direct reduction shaft (1) based on the measured flow rate of hydrogen-rich gas. where A method, characterized in that the flow rates of the iron ore and the sponge iron are controlled proportionally to the measured flow rate of the hydrogen-rich reducing gas.

2. 2. The method according to claim 1, comprising the further step of measuring the composition of the hydrogen-rich reducing gas, wherein the flow rate of iron ore to the shaft (1) and the flow rate of sponge iron extracted from the direct reduction shaft (1) are controlled based on the measured flow rate of the hydrogen-rich reducing gas and the measured composition of the hydrogen-rich reducing gas.

3. 3. The method according to claim 2, wherein the composition of the hydrogen-rich reducing gas is evaluated with respect to a content of reducing agent that will result in direct reduction of the iron ore, and wherein the content of reducing agent and the flow rate of the hydrogen-rich reducing gas are multiplied together to generate an input value based on which the flow rates of the iron ore and sponge iron are controlled.

4. 4. The method according to any one of claims 1 to 3, wherein the flow rates of the iron ore and the sponge iron are controlled so that they correspond to each other and that the combined level of iron ore and sponge iron in the direct reduction shaft (1) is maintained at a constant level.

5. 5. The method according to claim 1, wherein the flow rate of the hydrogen-rich reducing gas has a predetermined nominal value applied during predetermined nominal operating conditions of the direct reduction shaft (1), wherein a predetermined initial decrease in the flow rate of the hydrogen-rich gas from said nominal value to a threshold value is compensated by the addition of methane gas to the hydrogen-rich gas without a corresponding decrease in the flow rates of the iron ore and sponge iron, wherein the flow rates of the iron ore and sponge iron are controlled based on the measured flow rate of hydrogen gas once the flow rate of the hydrogen-rich gas is further decreased below said threshold value.

6. 6. The method of claim 5, further comprising the step of measuring the pressure in the direct reduction shaft (1), wherein the addition of the methane gas is controlled to maintain a nominal operating pressure in the direct reduction shaft (1) upon a decrease in the flow rate of the hydrogen-rich reducing gas from the nominal value to the threshold value.

7. The method of any one of claims 1 to 6, wherein the hydrogen-rich gas comprises at least 80% by weight of hydrogen gas.

8. The method of any one of claims 1 to 6, wherein the hydrogen-rich gas comprises at least 90% by weight of hydrogen gas.

9. The method of any one of claims 1 to 6, wherein the hydrogen-rich gas comprises at least 95% by weight of hydrogen gas.

10. 10. The method according to any one of claims 1 to 9, wherein the hydrogen-rich reducing gas is composed of hydrogen gas produced in the electrolyser and hydrogen gas obtained from the off-gas extracted from the direct reduction shaft (1).

11. 10. The method of claim 1, wherein the step of measuring the flow rate of hydrogen-rich gas comprises measuring the flow rate of hydrogen carried by the off-gas or measuring the flow rate of hydrogen gas obtained from the off-gas. Preferably, the method includes the step of mixing hydrogen gas from the electrolyser and hydrogen gas obtained from the off-gas, wherein the measurement is performed upstream of the point of mixing of said hydrogen gases, as seen in the flow direction of the respective hydrogen gases.

12. - direct reduction shaft (1), - a device (2) for charging the iron ore into the direct reduction shaft (1), - a device (3) for extracting sponge iron from the direct reduction shaft (1), - a hydrogen-rich reducing gas source (4), a reducing gas line (5) running from a hydrogen-rich reducing gas source (4, 13) directly to the reducing shaft (1); a heater (6) for heating the hydrogen-rich reducing gas in the reducing gas line (5) An installation for producing sponge iron, comprising: a flow meter (7) configured to measure the flow rate of the hydrogen-rich reducing gas in the reducing gas line (5); a control unit (8) configured to control a device (2) for charging iron ore into the direct reduction shaft (1) and to control a device (3) for extracting sponge iron from the direct reduction shaft (1) based on an input from a flow meter (7) such that the flow rate of the iron ore and the flow rate of sponge iron are proportional to the measured flow rate of the hydrogen-rich reducing gas; An equipment comprising:

13. 13. The installation according to claim 12, comprising a sensor (9) for measuring the composition of the hydrogen-rich reducing gas, wherein the control unit (8) is configured to control a device (2) for charging iron ore into the direct reduction shaft (1) and to control a device (3) for extracting sponge iron from the direct reduction shaft (1) based on an input from the sensor (9).

14. 14. The installation according to claim 13, wherein the control unit (8) is configured to evaluate the composition of the hydrogen-rich reducing gas with respect to a content of reducing means resulting in a direct reduction of the iron ore, to multiply the content of reducing means and the flow rate of the hydrogen-rich reducing gas together, and to generate input values ​​on the basis of which the device for charging the iron ore (2) and the device for extracting sponge iron (3) are controlled.

15. 15. The installation according to any one of claims 12 to 14, wherein the control unit (8) is configured to control the device (2) for charging iron ore into the direct reduction shaft (1) and to control the device (3) for extracting sponge iron from the direct reduction shaft (1) in such a way that the flows of iron ore and sponge iron correspond to each other and that the combined level of iron ore and sponge iron in the direct reduction shaft (1) is maintained at a constant level.

16. 16. The installation according to claim 12, comprising a methane gas source (10) and a valve device (11) for controlling a flow of methane gas from said methane gas source (10) to a reducing gas line (5), wherein a flow rate of the hydrogen-rich reducing gas has a predetermined nominal value applied during predetermined nominal operating conditions of the direct reduction shaft (1), and wherein in response to a predetermined initial measured decrease in the flow rate of the hydrogen-rich gas from said nominal value to a threshold value, the control unit (8) is configured to compensate for said decrease by controlling the addition of methane gas from the methane gas source to the hydrogen-rich reducing gas without a corresponding decrease in the flow rates of the iron ore and sponge iron, and wherein the control unit (8) is configured to control the flow rates of the iron ore and the sponge iron by controlling the device for charging the iron ore (2) and the device for extracting the sponge iron based on the measured flow rate of the hydrogen-rich reducing gas when the flow rate of the hydrogen-rich reducing gas further decreases below said threshold value.

17. 17. The installation according to claim 16, further comprising a sensor (12) for measuring the pressure in the direct reduction shaft (1), wherein the control unit (8) is configured to control the addition of the methane gas such that a nominal operating pressure in the direct reduction shaft (1) is maintained upon a decrease in the flow rate of the hydrogen-rich reducing gas from the nominal value to the threshold value.

18. 18. The installation according to any one of claims 12 to 17, wherein the hydrogen-rich reducing gas source comprises an off-gas return line (13) for returning the off-gas extracted from the electrolyser (4) and the direct reduction shaft (1).

19. 18. The installation according to claim 17, further comprising a flow meter (16) configured to measure a flow rate of hydrogen gas in the off-gas return line (13), wherein the control unit (8) is configured to control a device (2) for charging iron ore into the direct reduction shaft (1) and to control a device (3) for extracting sponge iron from the direct reduction shaft (1) based on an input from the flow meter (16).

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