Arrangement for direct reduction of iron ore to sponge iron
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-02-04
- Publication Date
- 2026-08-13
Smart Images
Figure SE2026010041_13082026_PF_FP_ABST
Abstract
Description
[0001] ARRANGEMENT FOR DIRECT REDUCTION OF IRON ORE TO SPONGE IRON
[0002] TECHNICAL FIELD
[0003] The present disclosure relates to an arrangement for direct reduction of iron ore to sponge iron and to a method for controlling an arrangement for direct reduction of iron ore to sponge iron.
[0004] BACKGROUND ART
[0005] An arrangement for direct reduction of iron ore to sponge iron may comprise a vertical direct reduction shaft having an inlet for introduction of iron ore at a top of the shaft and an outlet for direct reduced iron (DRI) at a bottom of the shaft. The arrangement may be a counterflow arrangement in which the iron ore and the DRI is permitted to flow downwards under the influence of the gravitational force, while the reduction gas flows in the opposite direction. Downstream the level at which the reduction gas is introduced into the shaft, cooling gas may be introduced into the shaft for the purpose of cooling the DRI.
[0006] In such an arrangement small particles and dust, also known as fines, may be accumulated within the direct reduction shaft, and especially within a lower portion of the shaft where cooling of the DRI takes place. The accumulation of fines may be even more increased in a shaft geometry where there are no gas outlets between the cooling gas inlet and the reduction gas inlet. The amount of fines being accumulated are affected by e.g. quality of the iron ore, type of reduction gas and / or cooling gas used, reduction temperature, distribution and velocities of gas streams within the shaft, geometry of the shaft and / or positions of gas outlets. The accumulation of fines inside the direct reduction shaft may cause redistribution of gas flows and / or asymmetric temperature distribution within the direct reduction shaft. This may cause uneven heat distribution of the DRI formed which may result in poor quality of the DRI, such as DRI having a too high temperature. In order to prevent a DRI with too high temperature, one option is to increase the cooling gas flow which in turn further may increase the accumulation of fines. It is thus an object of the present disclosure to provide an arrangement and a method for controlling direct reduction of iron ore to sponge iron, which provides for elimination of, or at least decreased, accumulation of fines within the direct reduction shaft.SUMMARY OF THE INVENTION
[0007] The object of the invention is achieved by an arrangement for direct reduction of iron ore to sponge iron, comprising:
[0008] -a vertical direct reduction shaft, said vertical direct reduction shaft having
[0009] -an inlet for introduction of iron ore at a top of the shaft and
[0010] -an outlet for direct reduced iron, DRI, at a bottom of the shaft,
[0011] -a reduction gas inlet for introduction of a reduction gas into the direct reduction shaft,
[0012] -a gas outlet for spent gas arranged upstream the reduction gas inlet as seen in the flow direction of the DRI,
[0013] -a cooling gas inlet for introduction of a cooling gas into the direct reduction shaft, arranged downstream the reduction gas inlet as seen in the flow direction of the DRI,
[0014] The arrangement further comprises:
[0015] -at least two temperature sensors arranged around the circumference of the direct reduction shaft (1) and at a level above the cooling gas inlet,
[0016] -a gas outlet arranged downstream the cooling gas inlet as seen in the flow direction of the DRI, and arranged for discharging cooling gas from the direct reduction shaft,
[0017] -a valve for controlling a gas flow through the gas outlet,
[0018] -a control unit, operatively connected to the temperature sensors and to the valve and configured to compare input data from the at least two temperature sensors and, controlling the valve based on the comparison, such that ATmax<x.
[0019] It has been realised by the applicant that temperature differences inside and around the inner periphery of the shaft are affected by the accumulation of fines, and that fines can be removed downwards in the shaft by means of a gas outlet downstream the cooling gas inlet as seen in the flow direction of the DRI. By the proposed arrangement, a part of the cooling gas is drawn downwards as seen in the flow direction of the DRI and the gas velocity becomes lower in an upper portion of the shaft as compared to if no cooling gas is drawn downwards. The fines are thereby transported towards the lower part of the shaft where the fines are discharged through the cooling gas outlet. It should be understood that the cooling gas outlet is either an integral part of or separate from the outlet for direct reduced iron. In addition, by the proposed arrangement accumulation of fines is further reduced since cooling gas being discharged fromthe direct reduction shaft via the outlet arranged downstream the cooling gas inlet as seen in the flow direction of the DRI withdraws fines from the shaft. In turn, the reduction of fines accumulation, results in a more evenly distributed temperature within a lower portion of the direct reduction shaft. Cooling of the DRI also takes place by means of the downwardly flowing stream of cooling gas such that the total amount of cooling gas needed is not affected by the proposed solution. According to some embodiments, the cooling gas outlet is an integral part of the outlet for direct reduced iron. According to some embodiments, the cooling gas outlet is separate from the outlet for direct reduced iron, x is a predetermined threshold value.
[0020] According to one embodiment, ATmax is the difference between the highest temperature value and the lowest temperature value being measured by the at least two temperature sensors. According to one embodiment, x is 25 °C.
[0021] According to one embodiment, x is 50 °C.
[0022] According to one embodiment, the at least two temperature sensors are arranged at the same level above the cooling gas inlet.
[0023] According to one embodiment, the arrangement comprises a plurality of temperature sensors evenly distributed around the circumference of the direct reduction shaft. According to some embodiments, the number of temperature sensors is more than two.
[0024] According to one embodiment, the temperature sensors are positioned at a level which is below the level at which the reduction gas inlet is positioned. Thereby, temperature measurement is performed in a zone in which fine accumulation is most likely to affect temperature.
[0025] According to one embodiment, the cooling gas comprises at least 80 %, preferably at least 90 %, most preferably at least 98 % hydrogen.
[0026] According to one embodiment, the reduction gas comprises at least 80 % hydrogen, preferably at least 85 %, most preferably at least 95 % hydrogen.
[0027] According to one embodiment, the direct reduction shaft is free from gas outlets between the level of the cooling gas inlet and the reduction gas inlet. In other words, there is no cooling gas outlet between the cooling gas inlet and the reduction gas inlet, and fines cannot be removed through such a cooling gas outlet. Thereby, the risk of fines accumulation increases. Cooling gas flowing upwards in the reduction zone may thus be used for the reduction, provided that the cooling gas comprises reduction gas and have a temperature being sufficient for reduction. This provides for an energy efficient arrangement.The object of the invention is also achieved by a method for controlling an arrangement for direct reduction of iron ore to sponge iron, comprising the steps of:
[0028] -introducing iron ore to an inlet of a vertical direct reduction shaft, said direct reduction shaft having the inlet for introduction of iron ore at a top and an outlet for DRI at a bottom, -removing direct reduced iron at the outlet of the direct reduction shaft,
[0029] -introducing a reduction gas at a reduction gas inlet of the direct reduction shaft, -removing a spent gas at a gas outlet arranged upstream the reduction gas inlet as seen in the flow direction of the DRI,
[0030] -introducing a cooling gas at a cooling gas inlet of the direct reduction shaft, arranged downstream the reduction gas inlet as seen in the flow direction of the DRI.
[0031] The method further comprises the steps of:
[0032] -measuring the temperature at at least two positions around the circumference of the direct reduction shaft at a level above the cooling gas inlet,
[0033] -comparing the temperature input data from the at least two positions,
[0034] -controlling a gas flow through a gas outlet arranged downstream the cooling gas inlet, based on the temperature input data comparison, such that ATmax<x.
[0035] The proposed method provides for the same advantages as described with regards to the arrangement above.
[0036] According to one embodiment, ATmax is the difference between the highest temperature value and the lowest temperature value being measured at the at least two positions.
[0037] According to one embodiment, x is 25 °C.
[0038] According to one embodiment, x is 50 °C.
[0039] According to one embodiment, measurement positions are arranged at the same level above the cooling gas inlet of the direct reduction shaft.
[0040] According to one embodiment, temperature is measured at a plurality of positions being evenly distributed around the circumference of the direct reduction shaft.
[0041] According to one embodiment, the temperature measurement positions are at a level below the level of the reduction gas inlet.
[0042] According to one embodiment, cooling gas comprises at least 80 %, preferably at least 90%, most preferably at least 98 % hydrogen.According to one embodiment, the reduction gas comprises at least 80 % hydrogen, preferably at least 85 %, most preferably at least 95 % hydrogen.
[0043] According to one embodiment, cooling gas flowing upwards in the shaft from the cooling gas inlet is removed from the shaft through the gas outlet arranged upstream the reduction gas inlet as seen in the flow direction of the DRI. According to some embodiments, a major part of the cooling gas flowing upwards in the shaft from the cooling gas inlet is removed from the shaft through the gas outlet arranged upstream the reduction gas inlet as seen in the flow direction of the DRL This may be referred to as regenerative cooling.
[0044] BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Fig. 1 schematically illustrates an arrangement for direct reduction of iron ore to sponge iron according to an exemplifying embodiment of the present disclosure.
[0046] Fig. 2 schematically illustrates an arrangement for direct reduction of iron ore to sponge iron according to another exemplifying embodiment of the present disclosure.
[0047] Fig. 3 schematically illustrates an arrangement for direct reduction of iron ore to sponge iron according to a further exemplifying embodiment of the present disclosure.
[0048] Fig. 4 schematically illustrates an arrangement for direct reduction of iron ore to sponge iron according to yet a further exemplifying embodiment of the present disclosure.
[0049] DETAILED DESCRIPTION
[0050] Fig. 1 schematically illustrates an arrangement for direct reduction of iron ore to sponge iron according to an exemplifying embodiment of the present disclosure.
[0051] The arrangement comprises a vertical direct reduction shaft 1. By “vertical” is meant that direct reduced iron (DRI) flows downwards by means of the gravitation towards a bottom of the shaft, whereas gases flow in an opposite direction upwards to a top of the shaft.
[0052] The vertical reduction shaft 1 has an inlet 2 for introduction of iron ore at the top of the shaft and an outlet 3 for DRI at a bottom of the shaft.
[0053] The vertical shaft 1 has a reduction gas inlet 9 for introduction of a reduction gas into the direct reduction shaft 1 , and a gas outlet 13 for spent gas arranged upstream the reduction gas inlet 9 as seen in the flow direction of the DRI. The gas outlet 13 may be referred to as a top gas outlet.The vertical shaft 1 has a cooling gas inlet 12 for introduction of a cooling gas into the direct reduction shaft 1 , arranged downstream the reduction gas inlet 9 as seen in the flow direction of the DRI.
[0054] The arrangement further comprises a hydrogen gas source 6. The hydrogen gas source 6 may comprise an electrolyser arranged to produced hydrogen gas from water. A first gas line 10 extends from the hydrogen gas source 6 to a heater arrangement 8 arranged to heat the hydrogen gas. The first gas line 10 further extends from the heater arrangement 8 to the reduction gas inlet 9. A first valve 18 is arranged to control the hydrogen gas flow to the reduction gas inlet 9.
[0055] A second gas line 11 extends from the hydrogen gas source 6 to a cooling gas inlet 12. A second valve 19 is arranged to control the hydrogen gas flow to the cooling gas inlet 12.
[0056] The hydrogen gas source may, but need not, be a common hydrogen gas source for the reduction gas and the cooling gas.
[0057] A third gas line 14 may extend from the gas outlet 13 to a first cleaning arrangement 7 arranged for cleaning of the spent gas by removal of water and dust from the spent gas. In one example, the cleaned spent gas generally consists of hydrogen gas. The third gas line 14 may further extend from the first cleaning arrangement 7 and be connected to the first gas line 10 at a location upstream the heater arrangement 8. Thereby, spent gas being removed via the gas outlet 13 from the direct reduction shaft 1 can be recycled.
[0058] The arrangement further comprises at least two temperature sensors Ti , T2 arranged around the circumference of the direct reduction shaft 1 and at a level above the cooling gas inlet 12. The arrangement further comprises a gas outlet 17 arranged downstream the cooling gas inlet 12 as seen in the flow direction of the DRI and arranged for discharging cooling gas from the direct reduction shaft 1.
[0059] The arrangement further comprises a valve 15 for controlling a gas flow through the gas outlet 17 and a control unit 16, operatively connected to the temperature sensors T1, T2 and to the valve 15 and configured to compare input data from the at least two temperature sensors T1 , T2 and, controlling the valve 15 based on the comparison, such that ATmax<x.
[0060] ATmax is the difference between the highest temperature value and the lowest temperature value being measured by the at least two temperature sensors T1 , T2.x is a predetermined measure of the temperature difference. In one embodiment, x is a temperature. According to one embodiment, x is 25 °C. According to another embodiment, x is 50 °C.
[0061] If ATmax exceeds x, the control unit 16 is arranged to control the valve 15 such that the gas flow through the gas outlet 17 is increased. Thereby the pressure at a lower portion of the direct reduction shaft, typically the portion wherein the cooling of the DRI takes place, is decreased which results in that at least a portion of the cooling gas flows downwardly as seen in the flow direction of the DRI. As a result, the gas velocity becomes become too low to lift the fines in an upper portion of the shaft and the fines are transported towards the lower part of the shaft where they are discharged though the gas outlet 17. In addition, the portion of the cooling gas flowing downwardly may bring fines to the gas outlet where they are discharged. As noted above, the cooling gas outlet may be an integral part of the outlet for direct reduced iron or the cooling gas outlet may be separate from the outlet for direct reduced iron.
[0062] When the valve 15 is closed, a main portion, or all, of the cooling gas will flow upwards within the shaft from the cooling gas inlet 12.
[0063] By fines is meant small particles having a diameter of less than 6.3 mm.
[0064] The at least two temperature sensors Ti , T2 may be arranged at the same level above the cooling gas inlet 12.
[0065] The temperature sensors may be positioned at a level which is below the level at which the reduction gas inlet is positioned.
[0066] The arrangement may comprise a plurality of temperature sensors evenly distributed around the circumference of the direct reduction shaft 1. According to one embodiment, the number of temperature sensors is four, wherein ATmax is the difference between the highest temperature value and the lowest temperature value being measured by the four temperature sensors. The cooling gas may comprise at least 80 %, preferably at least 90 %, most preferably at least 98 % hydrogen. In the disclosed embodiment, the cooling gas comprises approximately 98 % hydrogen gas.
[0067] The reduction gas may comprise at least 80 % hydrogen, preferably at least 85 %, most preferably at least 95 % hydrogen. In the disclosed embodiment, the reduction gas comprises approximately 95 % hydrogen gas.
[0068] It should be understood that other types of cooling gases and / or reduction gases can be used.The direct reduction shaft is free from gas outlets between the level of the cooling gas inlet and the reduction gas inlet. Thereby, cooling gas will flow towards the gas outlet 13 for spent gas arranged upstream the reduction gas inlet 9 as seen in the flow direction of the DRI, i.e. in an opposite direction as compared to the flow direction of the DRI.
[0069] The arrangement for direct reduction of iron ore to sponge iron may also comprise other components, such as compressors (not shown) for generating suitable gas pressures in the respective gas lines, as well as additional valves for controlling gas flows of reduction gas and cooling gas. The process pressure in the direct reduction shaft 1 may typically be in the region of 2-10 bars.
[0070] Fig. 2 schematically illustrates an arrangement for direct reduction of iron ore to sponge iron according to another exemplifying embodiment of the present disclosure. The arrangement in this embodiment comprises all parts as the arrangement described above. The arrangement further comprises a second gas cleaning arrangement 20 arranged to clean the gas from e.g. fines. In one example, the cleaned gas generally consists of hydrogen gas. A fourth gas line 21 extends from the valve 15 to the second gas cleaning arrangement 20. The fourth gas line 21 further extends from the second gas cleaning arrangement 20 to the second gas line 11 , such that the gas being removed from the gas outlet 17 and subjected to cleaning can be recycled as cooling gas. It should be understood that the cleaned gas may also be recycled as reduction gas. For example, the fourth gas line 21 may extend from the second gas cleaning arrangement 20 to the first gas line 10 which extends from the hydrogen gas source 6 to the heater arrangement 8 (not shown).
[0071] In the embodiments shown in Figs. 1 and 2, a major part of the cooling gas flowing upwards in the shaft from the cooling gas inlet 12 is removed from the shaft through the gas outlet 13 arranged upstream the reduction gas inlet 9 as seen in the flow direction of the DRI.
[0072] In the alternative embodiments, shown in Figs. 3 and 4, a major part of the cooling gas flowing upwards in the shaft from the cooling gas inlet 12 is removed from the shaft through a gas outlet 22 arranged above the cooling gas inlet 12 and below the reduction gas inlet 9.
[0073] In all embodiments above, at least a part of the gas being removed via the gas outlet 17 or through the gas outlet 22 may be flared (not shown).
[0074] The invention may also be performed by means of a method. The method may be performed by means of the above described arrangement.
[0075] The method comprises the following steps:-introducing iron ore to an inlet 2 of a vertical direct reduction shaft 1, said direct reduction shaft having the inlet 2 for introduction of iron ore at a top and an outlet 3 for DRI at a bottom, -removing direct reduced iron at the outlet 3 of the direct reduction shaft,
[0076] -introducing a reduction gas at a reduction gas inlet 9 of the direct reduction shaft 1, -removing a spent gas at a gas outlet 13 arranged upstream the reduction gas inlet 9 as seen in the flow direction of the DRI,
[0077] -introducing a cooling gas at a cooling gas inlet 12 of the direct reduction shaft 1, arranged downstream the reduction gas inlet 9 as seen in the flow direction of the DRI,
[0078] The method further comprises the steps of:
[0079] -measuring the temperature at at least two positions around the circumference of the direct reduction shaft 1 at a level above the cooling gas inlet 12,
[0080] -comparing the temperature input data from the at least two positions,
[0081] -controlling a gas flow through a gas outlet 17 arranged downstream the cooling gas inlet 12, based on the temperature input data comparison, such that ATmax<x.
[0082] ATmax is the difference between the highest temperature value and the lowest temperature value being measured at the at least two positions.
[0083] The measurement positions may be arranged at the same level above the cooling gas inlet 12 of the direct reduction shaft 1.
[0084] The temperature may be measured at a plurality of positions being evenly distributed around the circumference of the direct reduction shaft 1.
[0085] The temperature measurement positions may be at a level below the level of the reduction gas inlet.
[0086] The cooling gas may comprise at least 80 %, preferably at least 90%, most preferably at least 98 % hydrogen. In the disclosed embodiment, the cooling gas comprises approximately 98 % hydrogen gas.
[0087] The reduction gas may comprise at least 80 % hydrogen, preferably at least 85 %, most preferably at least 95 % hydrogen. In the disclosed embodiment, the reduction gas comprises approximately 95 % hydrogen gas.
[0088] It should be understood that other types of cooling gases and / or reduction gases can be used.In the embodiment shown in Figs. 1 and 2, a major part of the cooling gas flowing upwards in the shaft from the cooling gas inlet is removed from the shaft through the gas outlet 13 arranged upstream the reduction gas inlet 9 as seen in the flow direction of the DRL
[0089] In the alternative embodiments, shown in Figs. 3 and 4, a major part of the cooling gas flowing upwards in the shaft from the cooling gas inlet 12 is removed from the shaft through a gas outlet 22 arranged above the cooling gas inlet 12 and below the reduction gas inlet 9.
Claims
CLAIMS1. An arrangement for direct reduction of iron ore to sponge iron, comprising:-a vertical direct reduction shaft (1), said vertical direct reduction shaft having-an inlet (2) for introduction of iron ore at a top of the shaft and-an outlet (3) for direct reduced iron, DRI, at a bottom of the shaft,-a reduction gas inlet (9) for introduction of a reduction gas into the direct reduction shaft (1),-a gas outlet (13) for spent gas arranged upstream the reduction gas inlet (9) as seen in the flow direction of the DRI,-a cooling gas inlet (12) for introduction of a cooling gas into the direct reduction shaft (1), arranged downstream the reduction gas inlet (9) as seen in the flow direction of the DRI, characterized in that the arrangement further comprises:-at least two temperature sensors (Ti, T2) arranged around the circumference of the direct reduction shaft (1) and at a level above the cooling gas inlet (12),-a gas outlet (17) arranged downstream the cooling gas inlet (12) as seen in the flow direction of the DRI, and arranged for discharging cooling gas from the direct reduction shaft (1),-a valve (15) for controlling a gas flow through the gas outlet (17),-a control unit (16), operatively connected to the temperature sensors (T1, T2) and to the valve (15) and configured to compare input data from the at least two temperature sensors (T1, T2) and, controlling the valve (15) based on the comparison, such that ATmax<x, whereinATmax is the difference between the highest temperature value and the lowest temperature value being measured by the at least two temperature sensors (T1, T2) and x is a predetermined measure of the temperature difference.
2. The arrangement according to claim 1 , wherein x is 25 °C.
3. The arrangement according to claim 1 , wherein x is 50 °C.
4. The arrangement according to any of the preceding claims, wherein the at least two temperature sensors (T1, T2) are arranged at the same level above the cooling gas inlet (12).
5. The arrangement according to any of any of the preceding claims, comprising a plurality of temperature sensors (Ti, T2) evenly distributed around the circumference of the direct reduction shaft (1 ).
6. The arrangement according to any of the preceding claims, wherein the temperature sensors are positioned at a level which is below the level at which the reduction gas inlet is positioned.
7. The arrangement according to any of the preceding claims, wherein the cooling gas comprises at least 80 %, preferably at least 90%, most preferably at least 98 % hydrogen.
8. The arrangement according to any of the preceding claims, wherein the reduction gas comprises at least 80 % hydrogen, preferably at least 85 %, most preferably at least 95 % hydrogen.
9. The arrangement according to any of the preceding claims, wherein the direct reduction shaft is free from gas outlets between the level of the cooling gas inlet (12) and the reduction gas inlet (9).
10. A method for controlling an arrangement for direct reduction of iron ore to sponge iron, comprising the steps of:-introducing iron ore to an inlet (2) of a vertical direct reduction shaft (1), said direct reduction shaft having the inlet (2) for introduction of iron ore at a top and an outlet (3) for DRI at a bottom,-removing direct reduced iron at the outlet (3) of the direct reduction shaft, -introducing a reduction gas at a reduction gas inlet (9) of the direct reduction shaft (1), -removing a spent gas at a gas outlet (13) arranged upstream the reduction gas inlet (9) as seen in the flow direction of the DRI,-introducing a cooling gas at a cooling gas inlet (12) of the direct reduction shaft (1), arranged downstream the reduction gas inlet (9) as seen in the flow direction of the DRI,said method being characterised in that it further comprises the steps of:-measuring the temperature at at least two positions around the circumference of the direct reduction shaft (1) at a level above the cooling gas inlet (12),-comparing the temperature input data from the at least two positions,-controlling a gas flow through a gas outlet (17) arranged downstream the cooling gas inlet (12), based on the temperature input data comparison, such that ATmax<x, wherein ATmax is the difference between the highest temperature value and the lowest temperature value being measured at the at least two positions and x is a predetermined measure of the temperature difference.
11. The method according to claim 10, wherein x is 25 °C.
12. The method according to claim 10, wherein x is 50 °C.
13. The method according to any of claims 10 to 12, wherein the measurement positions are arranged at the same level above the cooling gas inlet (12) of the direct reduction shaft (1).
14. The method according to any of claims 10 to 13, wherein the temperature is measured ata plurality of positions being evenly distributed around the circumference of the direct reduction shaft (1).
15. The method according to any of claims 10 to 14, wherein the temperature measurement positions are at a level below the level of the reduction gas inlet.
16. The method according to any of claims 10 to 15, wherein the cooling gas comprises at least 80 %, preferably at least 90 %, most preferably at least 98 % hydrogen.
17. The method according to any of claims 10 to 16, wherein the reduction gas comprises at least 80 % hydrogen, preferably at least 85 %, most preferably at least 95 % hydrogen.
18. The method according to any of claims 10 to 17, wherein cooling gas flowing upwards in the shaft from the cooling gas inlet is removed from the shaft through the gas outlet (13) arranged upstream the reduction gas inlet (9) as seen in the flow direction of the DRI.