Method for feeding hydrogen into a shaft furnace for pure hydrogen reduction

Abstract

This invention proposes a method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction. The furnace comprises, from top to bottom, a preheating reduction zone, a high-temperature reduction zone, a constant pressure zone, and a cooling zone. The method includes: introducing preheated hydrogen into the preheating reduction zone to preheat the furnace charge; introducing a first high-temperature reducing hydrogen and a second high-temperature reducing hydrogen into the upper middle and lower parts of the high-temperature reduction zone, respectively, to reduce the furnace charge; and introducing cooling hydrogen into the cooling zone to cool the direct reduced iron generated during reduction. This invention solves the technical problems of high difficulty in temperature control and reduction reaction control in existing pure hydrogen vertical shaft furnaces. By introducing different types of reducing hydrogen into different areas of the furnace, the heat exchange and reduction reaction process can be controlled, thereby improving the metal reduction rate and reaction efficiency of the furnace.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, and in particular to a method for introducing reducing hydrogen into a pure hydrogen reduction vertical furnace. Background Technology

[0002] The global steel industry is actively exploring low-carbon metallurgical technologies, with gas-based vertical shaft furnace direct reduction technology rapidly transitioning to all-hydrogen smelting. However, existing technologies still face multiple challenges. For example, current green hydrogen production consumes a lot of energy, but the utilization rate of process waste heat is low; the strong endothermic nature of hydrogen reduction leads to large temperature fluctuations in the high-temperature zone, resulting in significant deviations in metallization rate; traditional solutions rely on high-investment external cooling circulation equipment, while simplified equipment technologies suffer from drawbacks such as cold reduction temperature control failure, gas mixing and segregation, and large fluctuations in product carbon content.

[0003] Current advancements in metallurgical technology are accelerating along two core directions: In the area of ​​low carbonization, existing technologies have demonstrated the feasibility of all-hydrogen smelting processes, but their large-scale application remains constrained by the high energy consumption bottleneck of green hydrogen production. In the area of ​​high efficiency, technologies for the cascade utilization of process waste heat exist, but the complexity of equipment due to multi-stage heat exchange systems leads to a surge in investment costs.

[0004] Inside the vertical shaft furnace, temperature control and reduction reaction control are very difficult due to factors such as the initial temperature of the hydrogen-containing reducing gas, gas flow rate, temperature distribution of sponge iron, and residence time. Temperature fluctuations can adversely affect the production stability of the vertical shaft furnace and even the reduction efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method for introducing reducing hydrogen into a pure hydrogen reduction shaft furnace, which solves the technical problems of high difficulty in temperature control and reduction reaction control in existing pure hydrogen shaft furnaces. By introducing different types of reducing hydrogen into different areas of the shaft furnace, the heat exchange and reduction reaction process of the shaft furnace can be controlled, thereby improving the metal reduction rate and reaction efficiency of the shaft furnace.

[0006] The above-mentioned technical objectives of the present invention are mainly achieved through the following technical solutions.

[0007] This invention provides a method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction. The furnace has, from top to bottom, a preheating reduction zone, a high-temperature reduction zone, a constant pressure zone, and a cooling zone. The method for introducing reducing hydrogen includes:

[0008] Preheated hydrogen is introduced into the preheating reduction zone to preheat the furnace charge; first high-temperature reducing hydrogen and second high-temperature reducing hydrogen are introduced into the upper middle and lower parts of the high-temperature reduction zone, respectively, to reduce the furnace charge; cooling hydrogen is introduced into the cooling zone to cool the direct reduced iron generated by reduction.

[0009] In a preferred embodiment of the present invention, the cooling hydrogen is introduced into the lower part of the cooling zone and the cooling exhaust gas generated after heat exchange is discharged from the upper part of the cooling zone into the vertical furnace.

[0010] In a preferred embodiment of the present invention, the cooling exhaust gas is used as the gas source for the preheated hydrogen and / or the second high-temperature reduced hydrogen.

[0011] In a preferred embodiment of the present invention, when the cooling exhaust gas is used as the gas source for the preheated hydrogen, the cooling exhaust gas is introduced into the preheating reduction zone after being treated with dust removal; when the cooling exhaust gas is used as the gas source for the first high-temperature reduced hydrogen, the cooling exhaust gas is introduced into the upper middle part of the high-temperature reduction zone after being treated with dust removal and heating.

[0012] In a preferred embodiment of the present invention, the furnace top process gas generated by the reaction of the preheated hydrogen, the first high-temperature reducing hydrogen, and the second high-temperature reducing hydrogen in the vertical furnace is exported from the furnace top and used as the gas source for the second high-temperature reducing hydrogen.

[0013] In a preferred embodiment of the present invention, when the furnace top process gas is used as the gas source for the second high-temperature reduced hydrogen, the furnace top process gas is introduced into the lower part of the high-temperature reduction zone after being treated by dust removal, dehydration, pressurization and heating.

[0014] In a preferred embodiment of the present invention, the furnace top process gas before dust removal and the furnace top process gas after pressurization are subjected to heat exchange treatment through a heat exchanger.

[0015] In a preferred embodiment of the present invention, the temperature of the cooling hydrogen gas introduced into the cooling zone is room temperature.

[0016] In a preferred embodiment of the present invention, the temperature of the preheated hydrogen gas introduced into the preheating reduction zone is 400°C to 750°C; and / or, the temperature of the first high-temperature reducing hydrogen gas introduced into the high-temperature reduction zone is 950°C to 1050°C.

[0017] In a preferred embodiment of the present invention, the temperature of the second high-temperature reducing hydrogen gas introduced into the high-temperature reduction zone is 950°C to 1050°C.

[0018] Compared with the prior art, the technical solution of the present invention has the following characteristics and advantages:

[0019] The pure hydrogen reduction vertical furnace hydrogen feeding method of this invention sets up gas inlet points in different functional areas along the axial direction of the vertical furnace to achieve a scientific distribution of the hydrogen fed into the furnace along the axial direction. Specifically, the cooling hydrogen introduced from the bottom of the cooling zone exchanges heat countercurrently with the high-temperature direct reduction iron to cool the product; the gas inlets in the lower and upper middle parts of the high-temperature reduction zone effectively maintain the stability of the reducing atmosphere and temperature field in that area; the gas inlet in the lower part of the preheating reduction zone significantly improves the preheating and pre-reduction efficiency of the pellets fed into the furnace, while achieving a smooth temperature transition between the preheating reduction zone and the high-temperature reduction zone.

[0020] The pure hydrogen reduction vertical furnace hydrogen feeding method of the present invention achieves efficient energy recycling through a cooling tail gas stage utilization mechanism. After dust removal treatment, part of the cooling tail gas is directly fed into the preheating reduction zone to preheat the pellets, and part of it is injected into the upper part of the high-temperature reduction zone for precise heat replenishment after heating. This effectively improves the thermal energy utilization rate of the cooling tail gas, while eliminating the need for traditional external cooling circulation equipment and reducing overall energy consumption.

[0021] The pure hydrogen reduction vertical furnace hydrogen feeding method of the present invention achieves efficient energy recycling through the recycling mechanism of furnace top process gas. After dust removal, dehydration, pressurization and heating treatment, the furnace top process gas is again fed into the lower part of the high temperature reduction zone as reducing gas, so as to reuse the unreacted part of the hydrogen in the furnace top process gas and recover the heat in the furnace top process gas, thereby reducing energy consumption. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0023] 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.

[0024] Figure 1 This is a process flow diagram of the pure hydrogen reduction vertical furnace hydrogen charging method described in this invention;

[0025] Figure 2 This is a process flow diagram of the first embodiment of the pure hydrogen reduction vertical furnace hydrogen charging method of the present invention;

[0026] Figure 3 This is a process flow diagram of the second embodiment of the pure hydrogen reduction vertical furnace hydrogen charging method of the present invention;

[0027] Figure 4 This is a process flow diagram of the third embodiment of the pure hydrogen reduction vertical furnace hydrogen feeding method of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 10. Preheated hydrogen; 20. First high-temperature reduced hydrogen; 30. Second high-temperature reduced hydrogen; 40. Cooling hydrogen; 50. Cooling tail gas; 60. Furnace top process gas. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0031] 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 "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0032] 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 invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] This invention provides a method for introducing reducing hydrogen into a pure hydrogen reduction vertical furnace, such as... Figure 1 As shown, the vertical furnace has, from top to bottom, a preheating reduction zone, a high-temperature reduction zone, a constant pressure zone, a cooling zone, and a discharge zone. The method of introducing reducing hydrogen into the furnace includes: introducing preheating hydrogen 10 into the preheating reduction zone to preheat the furnace charge; introducing first high-temperature reducing hydrogen 20 and second high-temperature reducing hydrogen 30 into the upper middle and lower parts of the high-temperature reduction zone, respectively, to reduce the furnace charge; and introducing cooling hydrogen 40 into the cooling zone to cool the direct reduced iron generated by reduction.

[0034] The pure hydrogen reduction vertical furnace hydrogen feeding method of the present invention sets up gas inlet points in different functional areas along the axial direction of the vertical furnace to achieve scientific distribution of hydrogen feeding along the axial direction of the vertical furnace, thereby achieving control of the reducing atmosphere and temperature field inside the vertical furnace, improving the preheating and pre-reduction efficiency of the furnace charge, and ensuring the quality of the furnace bottom product.

[0035] like Figure 1 As shown, a preheating hydrogen inlet is provided on the furnace wall corresponding to the preheating reduction zone of the vertical furnace. After the vertical furnace starts working, preheating hydrogen 10 is introduced into the preheating reduction zone through the preheating hydrogen inlet. The relatively high-temperature preheating hydrogen 10 flows upward and exchanges heat with the furnace charge in the opposite direction, which increases the temperature of the furnace charge and produces a partial reduction reaction (pre-reduction).

[0036] The air intake at the bottom of the preheating reduction zone enables a smooth temperature transition between the preheating reduction zone and the high-temperature reduction zone, avoiding significant temperature fluctuations in the high-temperature reduction zone and improving the reduction rate and effect of the furnace charge in the vertical furnace.

[0037] Preferably, the temperature of the preheated hydrogen gas 10 introduced into the preheating reduction zone is 400℃~750℃.

[0038] like Figure 1 As shown, a first reducing gas inlet is provided on the furnace wall in the upper part of the high-temperature reduction zone of the vertical furnace. After the vertical furnace starts working, the first high-temperature reducing hydrogen gas 20 is introduced into the high-temperature reduction zone through the first reducing gas inlet, thereby forming a high-temperature hydrogen field in the upper part of the high-temperature reduction zone. This provides precise heating to the upper part of the high-temperature reduction zone. The heating mechanism can extend the constant temperature zone of the high-temperature reduction zone and increase the residence time of the furnace charge in the high-temperature reduction zone. This can effectively solve the problem of high-temperature reduction zone shrinkage caused by furnace condition fluctuations and improve the overall stability of the process.

[0039] A second reducing gas inlet is provided on the furnace wall at the lower part of the high-temperature reduction zone of the vertical furnace. After the vertical furnace starts working, the second high-temperature reducing hydrogen gas 30 is introduced into the high-temperature reduction zone through the second reducing gas inlet, thereby forming a high-temperature hydrogen gas field at the lower part and above of the high-temperature reduction zone to realize the reduction of the furnace charge.

[0040] The air intake in the lower and upper middle parts of the high-temperature reduction zone effectively maintains the stability of the reducing atmosphere and temperature field in the region, while forming a self-sealing high-temperature zone. The large area of ​​the high-temperature reaction zone can improve the reduction rate and reaction efficiency of the furnace charge.

[0041] Preferably, the temperature of the first high-temperature reducing hydrogen gas 20 and the second high-temperature reducing hydrogen gas 30 introduced into the high-temperature reduction zone is 950℃~1050℃.

[0042] like Figure 1As shown, a cooling gas inlet is provided on the furnace wall corresponding to the cooling zone of the vertical furnace. After the vertical furnace starts working, cooling hydrogen gas 40 is introduced into the cooling zone through the cooling gas inlet. The cooling hydrogen gas 40 exchanges heat with the high-temperature direct reduced iron in a countercurrent manner to cool the direct reduced iron and prevent it from being oxidized again after being taken out of the furnace.

[0043] Preferably, the temperature of the cooling hydrogen gas 40 introduced into the cooling zone is room temperature, usually around 25°C.

[0044] The following describes the process of a preferred embodiment of the pure hydrogen reduction vertical furnace hydrogen charging method of the present invention.

[0045] According to one embodiment of the present invention, such as Figure 1 As shown, cooling hydrogen gas 40 is introduced into the lower part of the cooling zone, and the cooling exhaust gas 50 generated after heat exchange is discharged from the upper part of the cooling zone into the vertical furnace.

[0046] Specifically, the cooling gas inlet is located on the furnace wall at the lower part of the cooling zone, while the cooling gas outlet is located on the furnace wall at the upper part of the cooling zone. The cooling tail gas 50 generated after heat exchange with direct reduced iron is discharged from the vertical furnace through the cooling gas outlet. Since the temperature of the cooling tail gas 50 is lower than the gas temperature in the constant pressure zone and the reduction zone, in order to avoid temperature fluctuations and uneven temperature distribution caused by the mixing of hot and cold gases, the cooling zone and the constant pressure zone are separated, and the cooling tail gas 50 is continuously discharged from the cooling zone into the vertical furnace.

[0047] Furthermore, such as Figures 2 to 4 As shown, the cooling exhaust gas 50 is used as the hydrogen source for preheating hydrogen 10 and / or the second high-temperature reducing hydrogen 30, so as to achieve efficient energy recycling, improve the thermal energy utilization rate of the cooling exhaust gas 50, and eliminate the need for traditional external cooling circulation equipment, thereby reducing overall energy consumption.

[0048] In an alternative embodiment, such as Figure 2 As shown, the cooling exhaust gas 50 is used as the gas source for preheating hydrogen 10. After dust removal treatment, the cooling exhaust gas 50 is introduced into the preheating reduction zone to preheat the furnace charge.

[0049] The temperature of the cooling exhaust gas 50 generated in the cooling zone is between 400℃ and 750℃, which meets the temperature requirements of the preheating hydrogen gas 10. Therefore, the cooling exhaust gas 50 discharged from the upper part of the cooling zone is first treated by a dust collector, and then introduced into the lower part of the preheating reduction zone through the preheating hydrogen gas inlet, so as to realize the reverse flow of hydrogen gas from the high temperature zone to the medium and low temperature zone. During the upward movement, the cooling exhaust gas 50 exchanges heat with the furnace charge to preheat the furnace charge as the preheating hydrogen gas 10.

[0050] In an alternative embodiment, such as Figure 3As shown, the cooling exhaust gas 50 is used as the gas source for the second high-temperature reduced hydrogen gas 30. After being treated by dust removal and heating, the cooling exhaust gas 50 is introduced into the upper middle part of the high-temperature reduction zone to supplement the heat of the high-temperature reduction zone.

[0051] The temperature of the cooling exhaust gas 50 generated in the cooling zone is between 400℃ and 750℃. After being heated, it meets the temperature requirements of the first high-temperature reducing hydrogen 20. Therefore, the cooling exhaust gas 50 discharged from the upper part of the cooling zone is first treated by a dust collector, and then heated by a heater. After the gas temperature is raised to 950℃ to 1050℃, it is introduced into the middle and upper part of the high-temperature reduction zone from the first reducing gas inlet to serve as the first high-temperature reducing hydrogen 20 to realize the reduction of the furnace charge.

[0052] In an alternative embodiment, such as Figure 4 As shown, the cooling exhaust gas 50 is used as the gas source for both preheating hydrogen 10 and the second high-temperature reducing hydrogen 30. A portion of the cooling exhaust gas 50, after dust removal and heating treatment, is introduced into the upper middle part of the high-temperature reducing zone to supplement the heat of the high-temperature reducing zone; another portion of the cooling exhaust gas 50, after dust removal treatment, is introduced into the lower part of the preheating reducing zone to preheat the furnace charge.

[0053] The temperature of the cooling exhaust gas 50 generated in the cooling zone is between 400℃ and 750℃, which meets the temperature requirements of the preheating hydrogen 10. After being heated, it meets the temperature requirements of the first high-temperature reducing hydrogen 20. Therefore, a portion of the cooling exhaust gas 50 discharged from the upper part of the cooling zone is first treated by a dust collector, and then introduced into the lower part of the preheating reduction zone through the preheating hydrogen inlet to preheat the furnace charge as preheating hydrogen 10. Another portion of the cooling exhaust gas 50 discharged from the upper part of the cooling zone is first treated by a dust collector, and then heated to 950℃~1050℃ by a heater, and then introduced into the upper middle part of the high-temperature reduction zone through the first reducing gas inlet to reduce the furnace charge as the first high-temperature reducing hydrogen 20.

[0054] According to one embodiment of the present invention, such as Figure 1 and Figure 4 As shown, the furnace top process gas 60 generated by the reaction of preheated hydrogen 10, first high-temperature reducing hydrogen 20, and second high-temperature reducing hydrogen 30 in the vertical shaft furnace is discharged from the top of the furnace and used as the gas source for the second high-temperature reducing hydrogen 30. After dust removal, dehydration, pressurization, and heating treatment, the furnace top process gas 60 is introduced into the lower part of the high-temperature reduction zone. The recycling mechanism of the furnace top process gas 60 achieves efficient energy recycling and reduces energy consumption.

[0055] Specifically, such as Figure 4As shown, the top of the vertical shaft furnace has a process gas outlet. Gases reacted in the high-temperature reduction zone and preheating reduction zone converge at the top of the furnace and are discharged from the top process gas outlet into the top process gas treatment system. After treatment, this gas is used as second high-temperature reducing hydrogen 30 and reintroduced into the vertical shaft furnace through the second reducing gas inlet, completing the recycling process. The top process gas 60 treatment system includes a dust collector, a dehydrator, a compressor, and a heating furnace arranged sequentially.

[0056] The dust collector is used to remove dust particles and some water vapor from the gas; the dehydrator is used to remove liquid water from the gas; the pressurizer is used to pressurize the gas to meet the gas pressure and flow requirements of the vertical furnace reduction reaction; the heating furnace is used to heat the gas to meet the temperature requirements (950℃~1050℃) of the second high-temperature reduction hydrogen 30.

[0057] Better, such as Figure 4 As shown, the furnace top process gas 60 before dust removal and the furnace top process gas 60 after pressurization are heat exchanged through a heat exchanger.

[0058] The temperature of the furnace top process gas 60 before dust removal and dehydration is relatively high. After passing through the heat exchanger, the temperature decreases, which facilitates the subsequent dust removal and dehydration processes. At the same time, the pressurized furnace top process gas 60 is reintroduced into the heat exchanger, so that the heat is transferred back into the furnace top process gas 60. The furnace top process gas 60 cools down and then heats up again, realizing the recycling of heat.

[0059] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for introducing reducing hydrogen gas into a pure hydrogen reduction vertical furnace, characterized in that, The vertical shaft furnace, from top to bottom, comprises a preheating reduction zone, a high-temperature reduction zone, a constant pressure zone, and a cooling zone. The method for introducing reducing hydrogen into the furnace includes: Preheated hydrogen (10) is introduced into the preheating reduction zone to preheat the furnace charge; first high-temperature reducing hydrogen (20) and second high-temperature reducing hydrogen (30) are introduced into the upper middle and lower parts of the high-temperature reduction zone respectively to reduce the furnace charge; cooling hydrogen (40) is introduced into the cooling zone to cool the direct reduced iron generated by reduction.

2. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 1, characterized in that, The cooling hydrogen gas (40) is introduced into the lower part of the cooling zone and the cooling exhaust gas (50) generated after heat exchange is discharged from the upper part of the cooling zone into the vertical furnace.

3. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 2, characterized in that, The cooling exhaust gas (50) is used as the gas source for the preheated hydrogen (10) and / or the second high-temperature reduced hydrogen (30).

4. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 3, characterized in that, When the cooling exhaust gas (50) is used as the gas source for the preheated hydrogen (10), the cooling exhaust gas (50) is introduced into the preheating reduction zone after being treated with dust removal; when the cooling exhaust gas (50) is used as the gas source for the first high-temperature reduced hydrogen (20), the cooling exhaust gas (50) is introduced into the upper middle part of the high-temperature reduction zone after being treated with dust removal and heating.

5. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 1 or 3, characterized in that, The furnace top process gas (60) generated by the reaction of the preheated hydrogen (10), the first high-temperature reducing hydrogen (20) and the second high-temperature reducing hydrogen (30) in the vertical furnace is exported from the furnace top and used as the gas source for the second high-temperature reducing hydrogen (30).

6. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 5, characterized in that, When the furnace top process gas (60) is used as the gas source for the second high-temperature reducing hydrogen gas (30), the furnace top process gas (60) is introduced into the lower part of the high-temperature reduction zone after being treated by dust removal, dehydration, pressurization and heating.

7. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 6, characterized in that, The furnace top process gas (60) before dust removal and the furnace top process gas (60) after pressurization are heat exchanged through a heat exchanger.

8. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 1, characterized in that, The temperature of the cooling hydrogen gas (40) introduced into the cooling zone is room temperature.

9. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 1 or 4, characterized in that, The temperature of the preheated hydrogen gas (10) introduced into the preheating reduction zone is 400°C to 750°C; and / or the temperature of the first high-temperature reducing hydrogen gas (20) introduced into the high-temperature reduction zone is 950°C to 1050°C.

10. The method for introducing reducing hydrogen into a vertical shaft furnace for pure hydrogen reduction according to claim 6, characterized in that, The temperature of the second high-temperature reducing hydrogen gas (30) introduced into the high-temperature reduction zone is 950℃~1050℃.

Images