Direct reduction iron smelting method

Abstract

This invention discloses a direct reduction ironmaking method, relating to the field of iron and steel metallurgy. The direct reduction ironmaking method includes the following steps: splitting a first gas discharged from the preheating reduction zone into a first portion and a second portion; removing the inert gas from the first portion and mixing it with the second portion to form a second gas; heating the second gas to a first preset temperature and then inputting it into the high-temperature reduction zone, so that the second gas reacts with the iron-containing raw material and flows upward to the preheating reduction zone. This application can solve the problems of inert gas enrichment, unstable atmosphere, and low energy utilization in existing hydrogen-based reduction ironmaking processes.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a direct reduction ironmaking method. Background Technology

[0002] As the steel industry accelerates its transformation from a carbon-based metallurgical approach to a hydrogen-based one, direct reduction ironmaking, which uses hydrogen as the primary reducing agent, is considered an effective way to reduce carbon emissions. This method typically utilizes a vertical reactor to achieve gas-solid contact reduction of iron oxide, offering advantages such as continuous process, high energy efficiency, and the ability to be coupled with renewable energy-based hydrogen production.

[0003] Based on the progress made in pilot and demonstration phases of pure hydrogen shaft furnace reduction technology, related studies show that hydrogen reduction of iron oxide has good thermodynamic advantages, with theoretical emissions consisting only of water vapor. However, in practical applications, to ensure reactor pressure balance and operational safety, a small amount of inert gas (such as nitrogen) still needs to be introduced in some processes (such as charging and pressure equalization, and purging). If such gas accumulates continuously in the system, it will dilute the reducing atmosphere, affecting the reaction rate and product quality. In addition, most existing hydrogen-based reduction schemes focus on equipment structure optimization, lacking systematic exploration of reaction control methods in a hydrogen-inert gas mixed environment. The main challenges at present include: difficulty in dynamically controlling the inert gas concentration and low thermal utilization efficiency.

[0004] For example, patent application CN202110053605.7 discloses a hydrogen vertical furnace ironmaking system and method using electric heating. This system combines electric heating with tail gas diversion control to thermally regulate the inlet gas and furnace charge, thereby improving the overall thermal efficiency of the reactor and ensuring a safe transition during product cooling. This approach provides valuable insights into gas preheating, gas flow distribution, and thermal efficiency improvement, and has a certain promoting effect on the engineering application of vertical hydrogen reduction processes. While the aforementioned application proposes optimized solutions in terms of structural layout and heating methods, it lacks a dynamic control mechanism for the introduction and enrichment of inert gases, and does not address the system atmosphere changes caused by the introduction of inert gases such as nitrogen during reactor operation. In actual operation, to achieve uniform charging pressure or purging sealing, a small amount of inert gas is inevitably introduced into the system. If no control measures are implemented during long-term operation, nitrogen can easily accumulate in the circulating gas, diluting the reducing atmosphere, reducing the metal reduction reaction rate, and in severe cases, even causing process instability. Furthermore, existing direct reduction ironmaking methods still suffer from structural separation, low energy recovery efficiency, and the inability to simultaneously address product cooling, furnace temperature control, and economical exhaust gas treatment in terms of gas flow paths and heat utilization. Therefore, a novel method for direct reduction ironmaking is urgently needed to solve at least one of these problems. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the present invention is to provide a direct reduction ironmaking method, which can solve the problems of inert gas enrichment, unstable atmosphere and low energy utilization in the existing hydrogen-based reduction ironmaking process.

[0006] The specific technical solution of this invention is as follows:

[0007] A direct reduction ironmaking method is applied to a vertical shaft furnace. The vertical shaft furnace includes a furnace body with a feed port and a discharge port. The furnace body is divided into a preheating reduction zone, a high-temperature reduction zone, a cooling zone, and a discharge zone from top to bottom. The preheating reduction zone is connected to the feed port to preheat and perform initial reduction reactions on the feed input. The high-temperature reduction zone is used to reduce iron-containing raw materials with high-temperature hydrogen to generate direct reduced iron. The furnace body has a cooling gas inlet and a cooling gas outlet in the cooling zone to input cooling gas to cool the direct reduced iron. The discharge zone with the discharge port is used to discharge the direct reduced iron.

[0008] The direct reduction ironmaking method includes the following steps:

[0009] The first gas discharged from the preheating reduction zone is divided into a first part of first gas and a second part of first gas. Then, the inert gas in the first part of first gas is removed and mixed with the second part of first gas to form a second gas.

[0010] The second gas is heated to a first preset temperature and then input into the high-temperature reduction zone so that the second gas reacts with the iron-containing raw material and flows upward to the preheating reduction zone.

[0011] Preferably, the direct reduction ironmaking method includes the following steps:

[0012] Iron-containing raw materials are fed into the vertical furnace body through the feed port by inert gas purging or pressure equalization, thereby entering the preheating and reduction zone.

[0013] Preferably, the first preset temperature is between 950 degrees and 1050 degrees; the reaction temperature of the high-temperature reduction zone is controlled between 850 degrees and 1000 degrees.

[0014] Preferably, the first gas in the first part accounts for 10% to 20% of the first gas; the second gas in the first part accounts for 80% to 90% of the first gas.

[0015] Preferably, the step of splitting the first gas discharged from the preheating reduction zone into a first portion of first gas and a second portion of first gas includes:

[0016] The first gas discharged from the top of the vertical furnace body in the preheating and reduction zone is introduced into the first heat exchange channel of the heat exchanger.

[0017] The first gas after passing through the first heat exchange channel is subjected to dust removal and dehydration treatment;

[0018] The first gas, after dust removal and dehydration treatment, is introduced into the second heat exchange channel of the heat exchanger. Then, the first part of the first gas and the second part of the first gas are separated and heat exchanged between the first heat exchange channel and the second heat exchange channel.

[0019] Preferably, the first gas after dust removal and dehydration is pressurized and then introduced into the second heat exchange channel of the heat exchanger. After that, the first part of the first gas and the second part of the first gas are separated out.

[0020] Preferably, the direct reduction ironmaking method includes the following steps:

[0021] Cooling gas is introduced into the lower part of the cooling zone and made to flow upward to cool the downward-moving high-temperature direct reduced iron. The cooling gas includes hydrogen.

[0022] The heated cooling gas is discharged from the top of the cooling zone and fed into the preheating reduction zone.

[0023] Preferably, the step of discharging the heated cooling gas from the upper part of the cooling zone and inputting it into the preheating reduction zone includes:

[0024] The heated cooling gas is discharged from the top of the cooling zone and then subjected to dust removal treatment. The cooled gas after dust removal treatment is then input into the preheating reduction zone.

[0025] Preferably, the flow rate of the cooling gas introduced into the lower part of the cooling zone is 1.2 to 1.5 times the theoretical cooling requirement.

[0026] Preferably, the heated cooling gas is discharged from the top of the cooling zone, then subjected to dust removal treatment, and the dust-removed cooling gas is heated before being input into the preheating reduction zone.

[0027] Preferably, the location where the second gas is heated to the first preset temperature and then input into the high-temperature reduction zone is located at the lower part of the high-temperature reduction zone;

[0028] The cooling gas, after being treated for dust removal, is then introduced into the preheating reduction zone at the lower part of the preheating reduction zone. The cooling gas and the second gas, after reacting in the high-temperature reduction zone, combine to act on the iron-containing raw material.

[0029] The technical solution of the present invention has the following significant beneficial effects:

[0030] 1. The direct reduction ironmaking method proposed in this application, which uses hydrogen as the main reducing agent and inert gas as an auxiliary agent, systematically solves the problems of inert gas enrichment, unstable atmosphere and low energy utilization efficiency in the existing hydrogen-based reduction process through measures such as zoned gas supply and atmosphere control and inert gas removal.

[0031] 2. In this application, the first gas discharged from the preheating reduction zone is divided into a first part and a second part. Then, the inert gas in the first part is removed, and it is mixed with the second part to form a second gas. This second gas is then heated to a first preset temperature and introduced into the high-temperature reduction zone. Removing the inert gas from the first part prevents the gradual accumulation of inert gas within the furnace body, which could affect the reaction efficiency between hydrogen and iron-containing raw materials. Heating the second gas effectively avoids lowering the temperature of the high-temperature reduction zone, forming a high-enthalpy high-temperature reducing gas and ensuring the reaction efficiency of the high-temperature reduction zone. Furthermore, when the temperature of the high-temperature reduction zone is insufficient, the heated second gas can be used to supplement the heat in the high-temperature reduction zone.

[0032] Specific embodiments of the invention are disclosed in detail below with reference to the description and accompanying drawings, indicating how the principles of the invention can be employed. It should be understood that the embodiments of the invention are not therefore limited in scope. Features described and / or shown for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments. Attached Figure Description

[0033] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0034] Figure 1 This is a schematic diagram of the vertical furnace in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram illustrating the principle of the direct reduction ironmaking method in an embodiment of the present invention.

[0036] The reference numerals in the above figures are as follows:

[0037] 10. Vertical shaft furnace body; 11. Feed port; 12. Discharge port; 13. Preheating reduction zone; 14. High-temperature reduction zone; 15. Constant pressure zone; 16. Cooling zone; 17. Discharge zone; 18. First outlet; 19. Cooling gas inlet; 110. Cooling gas outlet; 20. Second gas distribution chamber; 21. Second gas buffer cavity; 22. First pipeline; 41. Gas transmission channel; 42. Second pipeline. Detailed Implementation

[0038] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "connected" should be interpreted broadly, for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] To address the problems of inert gas enrichment, unstable atmosphere, and low energy utilization in existing hydrogen-based reduction ironmaking processes, this application proposes a direct reduction ironmaking method. This direct reduction ironmaking method can be applied to vertical shaft furnaces.

[0041] Figure 1 This is a schematic diagram of the vertical furnace structure in an embodiment of the present invention, as shown below. Figure 1As shown, the vertical furnace may include: a vertical furnace body 10 having a feed port 11 and a discharge port 12. The interior of the vertical furnace body 10 is divided into a preheating reduction zone 13, a high-temperature reduction zone 14, a cooling zone 16, and a discharge zone 17 from top to bottom. The preheating reduction zone 13 is connected to the feed port 11 to preheat and perform initial reduction reaction on the iron-containing raw material input through the feed port 11. The high-temperature reduction zone 14 is used to reduce the iron-containing raw material with high-temperature hydrogen to generate direct reduced iron. The vertical furnace body 10 has a cooling gas inlet 19 and a cooling gas outlet 110 in the cooling zone 16 to input cooling gas to cool the direct reduced iron. The discharge zone 17 with the discharge port 12 is used to discharge the direct reduced iron.

[0042] like Figure 1 As shown, the feed port 11 can be located at the top of the shaft furnace body 10, for example, above or above the preheating reduction zone 13. The top of the shaft furnace body 10 can be formed by a feed channel extending into the interior of the shaft furnace body 10 to form the feed port 11. The preheating reduction zone 13 is connected to the feed port 11 to preheat and perform initial reduction reactions on the iron-containing raw material input through the feed port 11. The temperature of the preheating reduction zone 13 can be controlled between 600°C and 800°C. The iron-containing raw material input through the feed channel first enters the preheating reduction zone 13 during its downward movement. The iron-containing raw material can be pelletized or roasted iron-containing raw material, such as oxidized pellets, or it can be lump ore.

[0043] As a feasible option, such as Figure 1 As shown, the top of the vertical shaft furnace body 10 has a first outlet 18, which is used to discharge the hydrogen, water vapor, a small amount of inert gas, and dust remaining in the vertical shaft furnace body 10 that have not undergone reduction reaction with the iron-containing raw materials. Therefore, in the high-temperature reduction zone 14, hydrogen flows from bottom to top, from the high-temperature reduction zone 14 to the preheating reduction zone 13. The entire process is a reverse flow from the high-temperature zone to the medium-low temperature zone, using the residual heat in the hydrogen to preheat the iron-containing raw materials falling from top to bottom. The hydrogen, water vapor, a small amount of inert gas, and dust together form a first gas, which is then discharged from the first outlet 18 at the top of the vertical shaft furnace body 10.

[0044] As a feasible option, such as Figure 1As shown, the vertical shaft furnace body 10 may include a constant pressure zone 15, which is located between the high-temperature reduction zone 14 and the cooling zone 16 in the height direction. The constant pressure zone 15 is used to isolate the high-temperature hydrogen gas in the high-temperature reduction zone 14 from the hydrogen gas and inert gas in the cooling zone 16. The thermally reduced iron (HDRI) generated by the reduction reaction moves downward from the high-temperature reduction zone 14 into the constant pressure zone 15. The constant pressure zone 15 is a key structure connecting the high-temperature reduction zone 14 and the cooling zone 16. Its core function is to prevent cross-contamination between the high-temperature hydrogen gas in the high-temperature reduction zone 14 and the cooling gas in the cooling zone 16 through physical isolation and airflow control.

[0045] like Figure 1 As shown, the shaft furnace body 10 has a cooling gas inlet 19 and a cooling gas outlet 110 in the cooling zone 16 to input cooling gas to cool the thermally reduced iron (HDRI) formed by the reduction of iron oxides. The cooling gas inlet 19 is used to input cooling gas into the cooling zone 16, and the cooling gas outlet 110 is used to discharge the cooling gas after cooling the thermally reduced iron (HDRI). The thermally reduced iron (HDRI) moves downward from the constant pressure zone 15 into the cooling zone 16, where the cooling gas cools the metal to reduce the temperature of the thermally reduced iron to the required temperature.

[0046] like Figure 1 As shown, the discharge zone 17 has a discharge port 12. The cooled hot direct reduced iron enters the discharge zone 17 and is finally discharged from the vertical furnace body 10 through the discharge port 12.

[0047] Figure 2 This is a schematic diagram illustrating the principle of the direct reduction ironmaking method in an embodiment of the present invention, as shown below. Figure 2 As shown, the direct reduction ironmaking method in this application may include the following steps:

[0048] The first gas discharged from the preheating reduction zone 13 is divided into a first part of first gas and a second part of first gas. Then, the inert gas in the first part of first gas is removed and mixed with the second part of first gas to form a second gas.

[0049] In this step, by removing the inert gas from the first gas in the first part, the gradual enrichment of inert gas in the shaft furnace body 10 can be prevented, which would affect the reaction efficiency of hydrogen and iron-containing raw materials.

[0050] In this step, the first part of the first gas may account for 10% to 20% of the first gas; the second part of the first gas may account for 80% to 90% of the first gas.

[0051] As an option, the first gas in the preheating reduction zone 13 can be discharged from the top of the vertical furnace body 10. This would increase the time for the first gas to preheat the iron-containing raw materials and carry out the initial reduction reaction in the preheating reduction zone 13, thereby making full use of the first gas.

[0052] After the first gas in the preheating reduction zone 13 is discharged from the vertical furnace body 10, it enters the first heat exchange channel of the heat exchanger. The heat energy carried by the first gas is recovered by the heat exchanger for heating raw materials or other process gases. Then, the first gas after passing through the first heat exchange channel undergoes dust removal and dehydration treatment. Alternatively, dust removal can be performed using wet or dry dust removal methods to remove dust particles carried by the first gas from the vertical furnace body 10. Alternatively, moisture can be removed from the first gas using pressure swing adsorption, membrane separation, condensation, or drying devices. The order of dust removal and dehydration treatment of the first gas can be determined according to specific needs and the selected dust removal and dehydration methods, and is not limited in this application. Then, the dust-removed and dehydrated first gas is passed into the second heat exchange channel of the heat exchanger to complete the heating of the first gas. This method can improve heat utilization efficiency and reduce the need for additional external heat input.

[0053] As a feasible approach, to improve the reaction efficiency of the high-temperature reduction zone 14 and enhance the reduction reaction between hydrogen and iron oxides, the first gas, after dust removal and dehydration treatment, is pressurized before being introduced into the second heat exchange channel of the heat exchanger. Subsequently, the first portion of the first gas and the second portion of the first gas are separated. This process also maintains the pressure environment of the high-temperature reduction zone 14 to stabilize reaction conditions. The pressurized first gas replenishes the zone pressure, preventing pressure drops due to gas loss and ensuring the continuous and efficient progress of the reduction reaction.

[0054] The second gas is heated to a first preset temperature and then input into the high-temperature reduction zone 14 so that the second gas reacts with the iron-containing raw material and flows upward to the preheating reduction zone 13.

[0055] In this step, the second gas, heated to a first preset temperature, is introduced into the high-temperature reduction zone 14 at its lower part. This increases the contact time between the second gas and the iron-containing raw material, thereby enhancing the degree of reduction reaction. The gas heating method can be electric heating, gas heating, or industrial waste heat exchange, etc., and this application does not impose any limitations on these methods.

[0056] Since the reaction temperature between hydrogen and iron-containing raw materials in the high-temperature reduction zone 14 is controlled between 850°C and 1000°C, it is feasible to set the first preset temperature between 950°C and 1050°C. This effectively avoids lowering the temperature of the high-temperature reduction zone 14, preventing the formation of a high-enthalpy high-temperature reducing gas, and ensuring the reaction efficiency of the high-temperature reduction zone 14. Furthermore, when the temperature of the high-temperature reduction zone 14 is insufficient, the heated second gas can be used to supplement the heat in the high-temperature reduction zone 14.

[0057] As a feasible option, such as Figure 1 As shown, the vertical shaft furnace includes a second gas distribution chamber 20. The second gas distribution chamber 20 can be located on the outer periphery of the high-temperature reduction zone 14 of the vertical shaft furnace body 10. The second gas distribution chamber 20 has an annular second gas buffer cavity 21 and multiple circumferentially distributed inlets for inputting hydrogen gas, which communicate with the second gas buffer cavity 21. The second gas buffer cavity 21 is connected to the high-temperature reduction zone 14 through multiple circumferentially distributed first pipes 22 around the axis of the vertical shaft furnace body 10. The iron-containing raw material falling downwards reacts with the second gas input through the first pipes 22 to generate direct reduced iron. Hydrogen gas is introduced into the second gas buffer cavity 21 through multiple circumferentially distributed inlets connected to the second gas buffer cavity 21. Since the second gas buffer cavity 21 is annular, the second gas can be relatively uniformly dispersed in the second gas buffer cavity 21. Then, it flows into the high-temperature reduction zone 14 inside the vertical furnace body 10 through multiple first pipes 22 that are circumferentially distributed around the axis of the vertical furnace body 10. The uniform input of the second gas in the circumferential direction can effectively improve the airflow distribution in the high-temperature reduction zone 14, reduce the radial hydrogen concentration deviation, avoid metallization rate fluctuations caused by furnace charge segregation, ensure better heat exchange and reduction kinetic conditions, and improve the utilization rate of hydrogen gas and the reduction efficiency of metal oxides.

[0058] Furthermore, such as Figure 1 As shown, the first pipe 22 can be arranged in at least two layers, staggered vertically. This can improve the uniformity of the input hydrogen in the vertical direction, so that the high-temperature reduction zone 14 can have a relatively stable hydrogen flow at different positions in the vertical direction to carry out the reduction reaction with the downward falling metal oxide, further improving the utilization rate of hydrogen and the reduction efficiency of metal oxide.

[0059] As a feasible approach, the direct reduction ironmaking method may include the following steps:

[0060] Iron-containing raw materials are fed into the vertical furnace body 10 through the feed port 11 by inert gas purging or pressure equalization, thereby entering the preheating and reduction zone 13.

[0061] In this step, to prevent hydrogen leakage during the loading process and to maintain system pressure balance, inert gases (such as nitrogen, argon, etc.) are used for purging or pressure equalization. A small amount of inert gas is also introduced in this step.

[0062] As a feasible method, the direct reduction ironmaking method includes the following steps:

[0063] Cooling gas is introduced into the lower part of the cooling zone 16 and directed upwards to cool the downward-moving high-temperature direct reduced iron. The cooling gas includes hydrogen.

[0064] In this step, the cooling gas can be unheated pure hydrogen, thus avoiding the introduction of other inert gases. The cooling gas cools the high-temperature direct reduced iron, typically reducing it from around 800°C to around 100°C, while simultaneously heating itself and carrying away some water vapor and dust. The heated cooling gas becomes the exhaust gas. This process effectively recovers and utilizes the heat from the high-temperature direct reduced iron that will be discharged from the shaft furnace body 10.

[0065] In this step, as a feasible approach, the flow rate of the cooling gas introduced into the lower part of the cooling zone 16 is 1.2 to 1.5 times the theoretical cooling requirement. This ensures effective cooling of the high-temperature direct reduced iron and fully recovers waste heat resources. Furthermore, it guarantees the required amount of hydrogen gas for the reduction reaction at the feed port 11.

[0066] To improve the cooling effect of the cooling gas on the iron-containing raw materials, the vertical shaft furnace using hydrogen as a gas-based reducing agent may include: a first gas distribution chamber, which is located on the outer periphery of the cooling zone 16 of the vertical shaft furnace body 10. The first gas distribution chamber has an annular first gas buffer cavity and multiple circumferentially distributed inlets for inputting cooling gas that communicate with the first gas buffer cavity. The first gas buffer cavity is connected to the cooling zone 16 through multiple circumferentially distributed cooling gas inlets 19 around the axis of the vertical shaft furnace body 10.

[0067] The heated cooling gas is discharged from the upper part of the cooling zone 16 and input into the preheating reduction zone 13.

[0068] In this step, the heated cooling gas can be discharged from the top of the cooling zone 16, then subjected to dust removal treatment, and the dust-removed cooling gas is then input into the preheating reduction zone 13. The preheating reduction zone 13 not only receives the high-temperature reducing gas flowing counter-currently from the middle of the vertical furnace body 10, but also introduces the tail gas of the cooling gas from the cooling zone 16. The tail gas of the cooling gas carries a certain amount of sensible heat and hydrogen, and is introduced into the preheating reduction zone 13, where it merges with the high-temperature reducing gas flow after the reaction and acts together on the iron-containing furnace charge. The reuse of cooling gas not only effectively recovers waste heat resources, but also maintains the stability of the total amount of circulating gas and the reduction potential of the system.

[0069] In this step, the cooling gas after dust removal can be heated before being fed into the preheating reduction zone 13. This method not only achieves multi-stage utilization of the heat carried out by the cooling gas, but also allows for supplemental heating based on furnace conditions, improving the conversion rate of high-temperature direct reduced iron and ensuring or even increasing production capacity.

[0070] As a feasible option, the preheating reduction zone 13 of the vertical shaft furnace body 10 is provided with a second pipe 42 communicating with the interior of the vertical shaft furnace body 10. The cooling gas outlet 110 is connected to the second pipe 42 through the gas supply channel 41 to input the heated cooling gas into the preheating reduction zone 13. In this embodiment, heated hydrogen gas can be input into the preheating reduction zone 13 to preheat and initially reduce the iron-containing raw material.

[0071] As a feasible option, a dust collector and a heater are installed on the gas delivery channel 41 to achieve dust removal and heating purposes. Furthermore, a bypass channel connected in parallel with the heater is provided on the gas delivery channel 41. When heating of the hydrogen is not required, the hydrogen can pass through the bypass channel and be directly input into the lower part of the preheating reduction zone 13. After the hydrogen undergoes dust removal treatment by the dust collector, its temperature will further decrease from its original level; at this point, it can be determined whether to turn on the heater as needed.

[0072] To ensure uniform hydrogen input in the circumferential direction, effectively improve the gas flow distribution in the preheating reduction zone 13, reduce radial hydrogen concentration deviation, and avoid metallization rate fluctuations caused by charge segregation, the vertical furnace can, as a feasible option, include a third gas distribution chamber located on the outer periphery of the preheating reduction zone 13 of the furnace body 10. The third gas distribution chamber has an annular third gas buffer cavity and multiple circumferentially distributed inlets communicating with the third gas buffer cavity. The third gas buffer cavity is connected to the preheating reduction zone 13 through multiple second pipes 42 circumferentially distributed around the axis of the furnace body 10. This method can increase the contact area and heat transfer efficiency between hydrogen and the iron-containing raw material. After a stepped increase, the temperature of the iron-containing raw material can be efficiently reduced to the required temperature.

[0073] This application addresses the problem of insufficient utilization of the heat from the cooling gas discharged from cooling zone 16. In this application, this portion of hydrogen is given three stages of function: first, cooling metals, such as thermal direct reduced iron (HDRI); second, preheating iron-containing raw materials or supplementing the preheating of reduction zone 13; and third, preheating the purified hydrogen in a heat exchanger. The supplementary heating function allows for selection based on furnace conditions as to whether the cooling gas discharged from cooling gas outlet 110 needs to be heated via a heater. This method not only achieves multi-stage utilization of the heat carried out by the cooling gas but also allows for supplementary heating based on furnace conditions, improving product metallization rate and ensuring or even increasing production capacity.

[0074] Furthermore, the cooling gas, after dust removal treatment, is then input into the preheating reduction zone 13 at its lower part. The cooling gas and the second gas, after reacting in the high-temperature reduction zone 14, combine to act on the iron-containing raw material.

[0075] This application improves heat utilization efficiency by using hydrogen in a staged manner. The staged utilization involves first treating the hydrogen discharged from the cooling zone 16 with dust removal, then introducing it into the lower part of the preheating reduction zone 13, and then continuing to flow upwards. This achieves a reverse flow of hydrogen from the high-temperature zone to the medium-low temperature zone, utilizing the residual heat in the gas to preheat the iron-containing raw materials. Subsequently, the hydrogen discharged from the first outlet 18 at the top of the furnace enters the heat exchanger, where the heat in the hydrogen is used to preheat the purified hydrogen. This method effectively improves hydrogen utilization efficiency and reduces energy waste.

[0076] By utilizing hydrogen in stages, the residence time and metallization rate of iron-containing raw materials in the high-temperature reduction zone 14 can be ensured through supplementary heating without changing the feeding speed, thus guaranteeing output and improving heat utilization. By heating the cooling gas, its temperature can be raised to a suitable level before being introduced into the lower part of the preheating reduction zone 13. After the hydrogen is preheated in the heat exchanger, if the effective height of the high-temperature reduction zone 14 is reduced due to limitations on the temperature of the second gas entering the furnace, or fluctuations in furnace conditions, the second gas can be quickly heated to the target temperature using a heater to supplement the heat in the high-temperature reduction zone 14. This ensures the residence time of the iron-containing raw materials in the high-temperature reduction zone 14 and the preheating reduction zone 13, as well as the metallization rate of the product, thus making rational use of resources and reducing energy consumption.

[0077] The direct reduction ironmaking method proposed in this application, using hydrogen as the main reducing agent and inert gas as an auxiliary agent, systematically solves the problems of inert gas enrichment, unstable atmosphere, and low energy utilization efficiency in existing hydrogen-based reduction processes through measures such as zoned gas supply and atmosphere control, tail gas recycling, and inert gas removal. On the one hand, this application enhances the gas-solid countercurrent reaction effect by introducing a multi-section synergistic reaction structure, thereby improving the reduction reaction rate and metallization degree. On the other hand, through multi-stage reuse of cooling gas and the first gas discharged from the preheating reduction zone 13, the system's hydrogen recycling rate and energy efficiency are significantly improved. Simultaneously, this method achieves stable system pressure and safe operation by rationally introducing inert gas during the charging process. In summary, this process has the advantages of high reduction rate, strong atmosphere controllability, and good operational stability, providing a highly efficient new path for the industrial application of hydrogen-based direct reduction ironmaking.

[0078] In one specific embodiment, the oxidized pellets have a TFe content of 65%~67%, a particle size between 8 mm and 12 mm, and a bulk density of 2.1 t / m³. They are added from the top of the vertical furnace body 10 via an airtight hopper. During the charging process, industrial nitrogen with a purity of 99.99% is used as an inert gas for purging and pressure equalization, effectively preventing hydrogen leakage, while a small amount of nitrogen is introduced into the furnace.

[0079] The first gas discharged from the first outlet 18 at the top of the vertical furnace body 10 in the preheating reduction zone 13 undergoes heat exchange, dust removal, and dehydration treatment in the first heat exchange channel of the heat exchanger. After being pressurized, it enters the second heat exchange channel of the heat exchanger for further heating to form a circulating gas. To prevent nitrogen enrichment, 15% of the total circulating gas from the first gas is diverted for nitrogen removal. The denitrified gas is then remixed with the remaining 85% of the gas and heated to 1050°C in the heating unit before being piped into the high-temperature reduction zone 14. During this process, a bag filter removes over 99% of the dust; a dehydration device effectively removes 99% of the moisture from the gas; and a gas compressor increases the pressure of the treated first gas to 0.3~0.5 MPa.

[0080] 99.9% pure room-temperature hydrogen is used as the cooling gas, introduced from the bottom of the furnace at a flow rate of 1.2 to 1.5 times the theoretical cooling requirement, to cool the high-temperature direct reduced iron. After being heated and treated for dust removal, the cooling gas is introduced into the preheating reduction zone 13 of the vertical furnace body 10.

[0081] After being loaded into the feed port 11 of the vertical shaft furnace body 10, the oxidized pellets move gradually from top to bottom of the furnace body 10 under gravity. Inside the furnace body 10, this movement process passes through three functional zones in sequence: a preheating and pre-reduction zone, which heats up the material and performs initial reduction; a high-temperature reduction zone 14, where the material temperature rises to 850~950℃, iron oxides are reduced to metallic iron, and the oxidized pellets gradually transform into metallized pellets, i.e., high-temperature direct reduced iron; and a cooling zone 16, where the high-temperature direct reduced iron continues to move downwards and exchanges heat countercurrently with the cooling gas introduced from the cooling zone 16 of the furnace body 10, gradually being cooled to below 100℃, reaching a suitable discharge temperature, and finally discharged from the discharge zone 17.

[0082] Through the above embodiments, the metallization rate of DRI products can reach over 94%, avoiding the problem of inert gas enrichment, and significantly improving energy efficiency and process stability.

[0083] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified element, component, part, or step, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute “may” include is optional. Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The disclosure of “a” or “an” used to describe an element, component, part, or step does not imply exclusion of other elements, components, parts, or steps.

[0084] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A direct reduction ironmaking method, characterized in that, The direct reduction ironmaking method is applied to a vertical shaft furnace, which includes a furnace body with a feed port and a discharge port. The furnace body is divided into a preheating reduction zone, a high-temperature reduction zone, a cooling zone, and a discharge zone from top to bottom. The preheating reduction zone is connected to the feed port to preheat and perform initial reduction reactions on the feed input. The high-temperature reduction zone is used to reduce iron-containing raw materials with high-temperature hydrogen to generate direct reduced iron. The furnace body has a cooling gas inlet and a cooling gas outlet in the cooling zone to input cooling gas to cool the direct reduced iron. The discharge zone with the discharge port is used to discharge the direct reduced iron. The direct reduction ironmaking method includes the following steps: The first gas discharged from the preheating reduction zone is divided into a first part of first gas and a second part of first gas. Then, the inert gas in the first part of first gas is removed and mixed with the second part of first gas to form a second gas. The second gas is heated to a first preset temperature and then input into the high-temperature reduction zone so that the second gas reacts with the iron-containing raw material and flows upward to the preheating reduction zone.

2. The direct reduction ironmaking method according to claim 1, characterized in that, The direct reduction ironmaking method includes the following steps: Iron-containing raw materials are fed into the vertical furnace body through the feed port by inert gas purging or pressure equalization, thereby entering the preheating and reduction zone.

3. The direct reduction ironmaking method according to claim 1, characterized in that, The first preset temperature is between 950 degrees and 1050 degrees; the reaction temperature of the high-temperature reduction zone is controlled between 850 degrees and 1000 degrees.

4. The direct reduction ironmaking method according to claim 1, characterized in that, The first part of the first gas accounts for 10% to 20% of the first gas; the second part of the first gas accounts for 80% to 90% of the first gas.

5. The direct reduction ironmaking method according to claim 1, characterized in that, The step of splitting the first gas discharged from the preheating reduction zone into a first portion of first gas and a second portion of first gas includes: The first gas discharged from the top of the vertical furnace body in the preheating and reduction zone is introduced into the first heat exchange channel of the heat exchanger. The first gas after passing through the first heat exchange channel is subjected to dust removal and dehydration treatment; The first gas, after dust removal and dehydration treatment, is introduced into the second heat exchange channel of the heat exchanger. Then, the first part of the first gas and the second part of the first gas are separated and heat exchanged between the first heat exchange channel and the second heat exchange channel.

6. The direct reduction ironmaking method according to claim 5, characterized in that, After the first gas has undergone dust removal and dehydration treatment, it is pressurized and then introduced into the second heat exchange channel of the heat exchanger. After that, the first part of the first gas and the second part of the first gas are separated out.

7. The direct reduction ironmaking method according to claim 1, characterized in that, The direct reduction ironmaking method includes the following steps: Cooling gas is introduced into the lower part of the cooling zone and made to flow upward to cool the downward-moving high-temperature direct reduced iron. The cooling gas includes hydrogen. The heated cooling gas is discharged from the top of the cooling zone and fed into the preheating reduction zone.

8. The direct reduction ironmaking method according to claim 7, characterized in that, The step of discharging the heated cooling gas from the top of the cooling zone and inputting it into the preheating reduction zone includes: The heated cooling gas is discharged from the top of the cooling zone and then subjected to dust removal treatment. The cooled gas after dust removal treatment is then input into the preheating reduction zone.

9. The direct reduction ironmaking method according to claim 7, characterized in that, The flow rate of the cooling gas introduced into the lower part of the cooling zone is 1.2 to 1.5 times the theoretical cooling requirement.

10. The direct reduction ironmaking method according to claim 8, characterized in that, The heated cooling gas is discharged from the top of the cooling zone, then subjected to dust removal treatment. The dust-removed cooling gas is then heated and input into the preheating reduction zone.

11. The direct reduction ironmaking method according to claim 7, characterized in that, The second gas, after being heated to the first preset temperature, is input into the high-temperature reduction zone at the lower part of the high-temperature reduction zone. The cooling gas, after being treated for dust removal, is then introduced into the preheating reduction zone at the lower part of the preheating reduction zone. The cooling gas and the second gas, after reacting in the high-temperature reduction zone, combine to act on the iron-containing raw material.

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