A fully automated four-tube reduction furnace for hydrogen reduction

Abstract

The application provides a full-automatic four-tube reduction furnace for hydrogen reduction, relates to the technical field of micro-nano metal powder reduced by hydrogen, and comprises a main pushing system, a feeding system, a main furnace tube, an air cooling furnace tube, a circulating water cooling furnace tube and a discharging system which are sequentially connected; the feeding system is provided with an inner kiln head door, an outer kiln head door and a kiln head replacement chamber, and the inner kiln head door and the outer kiln head door are alternately opened and closed; the discharging system is provided with an inner kiln tail door, an outer kiln tail door and a kiln tail replacement chamber, and the inner kiln tail door and the outer kiln tail door are alternately opened and closed. The discharging system and the feeding system are in the form of double-layer door sealing and replacement chamber, the doors are alternately opened and closed in the production process, the inner door is elastic, the outer door is rigid, heat deformation is avoided to cause sealing failure, hydrogen leakage and consumption are reduced, and in addition, the replacement chamber serves as an intermediate buffer layer, so that the gas pressure fluctuation interference to the furnace atmosphere and the reduction effect can be avoided.

Description

Technical Field

[0001] This utility model discloses a fully automated four-tube reduction furnace for hydrogen reduction, relating to the field of micro-nano metal powder technology for hydrogen reduction. Background Technology

[0002] In the preparation process of micro and nano metal powders, double-tube or four-tube reduction furnaces are commonly used for primary or secondary reduction with hydrogen. To improve production capacity, four-tube reduction furnaces are mostly used. "Four tubes" refers to two rows of two tubes arranged vertically inside the furnace, for a total of four rectangular furnace tubes. Under high temperature conditions, metal powder oxides are reduced to elemental metal powders in a hydrogen atmosphere within the reduction furnace. Currently, four-tube reduction furnaces have the following problems: the reduction furnace uses a single-door method, resulting in significant hydrogen consumption during door opening and closing, and posing a considerable safety hazard. Therefore, we have made improvements and proposed a fully automated four-tube reduction furnace and method for hydrogen reduction. Utility Model Content

[0003] This utility model provides a fully automated four-tube reduction furnace for hydrogen reduction, comprising a main propulsion system, a feeding system, a main furnace tube, an air-cooled furnace tube, a circulating water-cooled furnace tube, and a discharge system connected in sequence.

[0004] The feeding system is equipped with an inner kiln head door, an outer kiln head door, and a kiln head replacement chamber, and the inner kiln head door and the outer kiln head door open and close alternately; the discharging system is equipped with an inner kiln tail door, an outer kiln tail door, and a kiln tail replacement chamber, and the inner kiln tail door and the outer kiln tail door open and close alternately to form a double-layer sealing structure.

[0005] As a preferred technical solution of this application, the feeding system is fixed to the main furnace tube, air-cooled furnace tube, circulating water-cooled furnace tube, and discharge system by means of flange connection.

[0006] As a preferred technical solution of this application, it also includes a support system, wherein the main pushing system is connected to the feeding system and fixed on the upper part of the support system.

[0007] As a preferred technical solution of this application, it also includes a furnace shell, a furnace lining, a kiln tail atmosphere control system, a kiln head atmosphere control system, and a preheating hydrogen supply device. The furnace shell and the furnace lining are equipped with heaters. After being metered by the kiln tail atmosphere control system, ambient temperature hydrogen is heated by the heaters and then sent to the preheating hydrogen supply device. Protective gas nitrogen is metered by the kiln head atmosphere control system and then sent into the furnace lining.

[0008] As a preferred technical solution of this application, it also includes a hydrogen recovery back pressure system, which is connected to a hydrogen recovery and purification system; the main furnace tubes are arranged in two vertical rows, with two tubes in each row; the hydrogen outlets of the four main furnace tubes are collected and fed into the hydrogen recovery back pressure system before entering the hydrogen recovery and purification system.

[0009] As a preferred technical solution of this application, it also includes a circulating rotary system, wherein the feeding system and the discharging system are connected together with the circulating rotary system, and the circulating rotary system is equipped with an automatic unloading device and an automatic loading device.

[0010] As a preferred technical solution of this application, it also includes a double-layer boat, which consists of an upper boat, a lower boat, and a graphite pad placed from top to bottom. The graphite pad is placed on a circulating rotary system to circulate among the automatic loading device, the feeding system, the main furnace tube, the air-cooled furnace tube, the circulating water-cooled furnace tube, the discharge system, and the automatic unloading device.

[0011] As a preferred technical solution of this application, it also includes a control system, which controls the automated operation of the four-tube reduction furnace via a PLC.

[0012] A method for hydrogen reduction, using a fully automated four-tube reduction furnace for hydrogen reduction, includes the following steps:

[0013] The material to be reduced is loaded into the upper and lower boats by an automatic loading device and placed on a graphite pad. After passing through the feeding system, main furnace tube, air-cooled furnace tube, circulating water-cooled furnace tube, and discharge system, it returns to the circulating rotary system. During this process, ambient temperature hydrogen is metered by the kiln tail atmosphere control system, heated by the heater, and then sent to the preheating hydrogen supply device and into the furnace. Protective gas nitrogen is metered by the kiln head atmosphere control system and then sent into the furnace lining. The material passes through the main furnace tube, air-cooled furnace tube, and circulating water-cooled furnace tube in sequence before reaching the discharge system.

[0014] As a preferred technical solution of this application, after the material arrives at the discharge system, it returns to the circulation system, is unloaded by the automatic unloading device, and is then loaded by the automatic loading device, repeating the entire cycle.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0016] In the scheme of this application:

[0017] This application establishes a discharge system and a feeding system, both of which employ a double-door sealing and replacement chamber design. During production, the doors are opened and closed alternately, with the inner door remaining flexible and the outer door maintaining rigidity. This prevents thermal deformation from causing seal failure, reducing hydrogen leakage and consumption. Furthermore, the replacement chamber acts as an intermediate buffer layer, preventing pressure fluctuations from interfering with the furnace atmosphere and affecting the reduction effect, while also improving the safety factor. Attached Figure Description

[0018] Figure 1 This is a plan view of the overall layout of this utility model;

[0019] Figure 2 This is the overall elevation layout of the present invention;

[0020] Figure 3 This is a structural diagram of the feeding system of this utility model;

[0021] Figure 4 This is a structural diagram of the discharge system of this utility model;

[0022] Figure 5 This is a structural diagram of the upper and lower boats and the boats of this utility model;

[0023] In the diagram: 1. Main propulsion system; 2. Feeding system; 3. Support system; 4. Furnace shell; 5. Furnace lining; 6. Main furnace tube; 7. Air-cooled furnace tube; 8. Circulating water-cooled furnace tube; 9. Discharge system; 10. Hydrogen recovery back pressure system; 11. Control system; 12. Circulating rotary system; 13. Kiln tail atmosphere control system; 14. Kiln head atmosphere control system; 15. Preheating hydrogen delivery device; 16. Upper boat; 17. Lower boat; 18. Graphite pad; 19. Automatic unloading device; 20. Automatic loading device; 21. Kiln head inner door; 22. Kiln head outer door; 23. Kiln head replacement chamber; 24. Kiln tail inner door; 25. Kiln tail outer door; 26. Kiln tail replacement chamber; 27. Heater. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0025] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] Example 1, please refer to Figures 1-5A fully automated four-tube reduction furnace for hydrogen reduction includes a main propulsion system 1, a feeding system 2, a main furnace tube 6, an air-cooled furnace tube 7, a circulating water-cooled furnace tube 8, and a discharge system 9 connected in sequence. The reasonable system connection sequence is the basis for ensuring the smooth operation of the entire reduction process. Each system performs its own function and cooperates with each other, so that the material can undergo reduction reaction in the furnace according to a predetermined path.

[0028] The feeding system 2 is equipped with an inner kiln head door 21, an outer kiln head door 22, and a kiln head replacement chamber 23, with the inner kiln head door 21 and the outer kiln head door 22 opening and closing alternately. The discharging system 9 is equipped with an inner kiln tail door 24, an outer kiln tail door 25, and a kiln tail replacement chamber 26, with the inner kiln tail door 24 and the outer kiln tail door 25 opening and closing alternately to form a double-layer sealing structure. The double-layer sealing structure effectively prevents gas leakage inside the furnace and the entry of outside air, ensuring the stability and purity of the atmosphere inside the furnace and improving the quality and efficiency of the reduction reaction. Because the stability and purity of the atmosphere inside the furnace are crucial in the hydrogen reduction process, the double-layer sealing structure can better isolate the internal and external environments, reduce gas exchange, and create favorable conditions for the reduction reaction.

[0029] Furthermore, the feeding system 2 is fixed to the main furnace tube 6, air-cooled furnace tube 7, circulating water-cooled furnace tube 8, and discharge system 9 by means of flange connection; in industrial production, the equipment needs to be maintained and repaired regularly, and the flange connection can be quickly disassembled and installed, reducing maintenance time and cost, and the good sealing performance can prevent gas leakage.

[0030] Furthermore, it also includes a support system 3, on which the main propulsion system 1 and the feeding system 2 are connected and fixed. The support system 3 provides stable support for the main propulsion system 1 and the feeding system 2, ensuring the stability and safety of the equipment during operation.

[0031] Furthermore, it also includes a furnace shell 4, a furnace lining 5, a kiln tail atmosphere control system 13, a kiln head atmosphere control system 14, and a preheating hydrogen supply device 15. Heaters 27 are installed inside the furnace shell 4 and the furnace lining 5. Room temperature hydrogen is metered by the kiln tail atmosphere control system 13, heated by the heater 27, and then fed into the preheating hydrogen supply device 15. Protective gas nitrogen is metered by the kiln head atmosphere control system 14 and then fed into the furnace lining 5. In the prior art, the reducing gas hydrogen is supplied at room temperature without preheating, which reduces the hydrogen reduction efficiency. This application preheats the hydrogen, enhancing molecular activity and significantly improving the reduction reaction efficiency, lowering the initial reaction temperature, and reducing the heating power inside the furnace, thus offering energy-saving and consumption-reducing advantages. Preheated hydrogen has better diffusion, reducing the amount of excess hydrogen introduced, and making the reaction more uniform, avoiding localized low temperatures that could cause metal particles to stick together, resulting in a more concentrated powder particle size distribution. Additionally, preheating the hydrogen lowers its dew point, reducing the generation of condensate inside the furnace and effectively preventing the risk of secondary oxidation.

[0032] Furthermore, it also includes a hydrogen recovery back pressure system 10, which is connected to a hydrogen recovery and purification system; the main furnace tubes 6 are arranged in two vertical rows, with two tubes in each row; the hydrogen outlets of the four main furnace tubes 6 are collected and then enter the hydrogen recovery and purification system after passing through the hydrogen recovery back pressure system 10; in existing technologies, reduction furnaces generally use ignition, and the utilization rate of hydrogen during production is only about 17%, which is low; this application adopts a hydrogen recovery method, where about 80% of the hydrogen is not reacted, and after recovery and purification, it can be recycled, significantly reducing production costs, while eliminating the safety hazards of direct ignition of tail gas, improving safety and environmental friendliness; it reduces the amount of inert protective gas used, reducing overall costs, and the recovery system can maintain a stable inlet pressure of the reduction furnace, avoiding uneven reaction caused by pressure fluctuations; after purification, the dew point of the recovered hydrogen can be reduced to below -60℃, and the oxygen content is less than 1ppm, effectively preventing the oxidation of metal powder.

[0033] Furthermore, it also includes a circulating rotary system 12, with the feeding system 2 and the discharging system 9 connected together. The circulating rotary system 12 is equipped with an automatic unloading device 19 and an automatic loading device 20. The automatic unloading device 19 and the automatic loading device 20 reduce manual intervention and improve the automation level and production efficiency of the production.

[0034] Furthermore, it also includes a double-layer boat dish, which consists of an upper boat dish 16, a lower boat dish 17, and a graphite pad 18 placed from top to bottom. In the prior art, the boat dish is in direct contact with the furnace tube, and the friction between the furnace tube and the boat dish is large during the boat pushing process, which greatly reduces the service life of the furnace tube. This application adopts the form of graphite pad 18 plus upper boat dish 16 and lower boat dish 17, which can effectively reduce the friction with the furnace tube and improve the service life of the boat dish and the furnace tube. In addition, the double-layer boat dish form can buffer thermal shock, and the material is heated more evenly. There is a gap between the double-layer boat dish, which can allow the reducing gas to penetrate evenly into the material layer, forming laminar flow, reducing dead zones, improving reduction efficiency and hydrogen utilization, and significantly increasing production capacity.

[0035] The graphite pad 18 is placed on the circulating rotary system 12 to circulate between the automatic loading device 20, the feeding system 2, the main furnace tube 6, the air-cooled furnace tube 7, the circulating water-cooled furnace tube 8, the discharge system 9, and the automatic unloading device 19.

[0036] In existing technologies, high-temperature furnace tubes are directly connected to circulating water-cooled furnace tubes, resulting in significant thermal shock and a high risk of stress cracking. This application, however, utilizes an air-cooled furnace tube 7 and a circulating water-cooled furnace tube 8 to achieve a combined air-cooling and water-cooling cooling method. Air cooling lowers the high temperature to a medium temperature, while water cooling lowers it to a low temperature, avoiding the thermal shock damage to the furnace tubes caused by direct water cooling. This also prevents hydrogen embrittlement or deformation of the flanges, extending the service life of critical components. With direct water cooling, if the furnace body seal fails, water vapor can react chemically with hydrogen, posing a risk of hydrogen explosion. Air cooling, on the other hand, prioritizes the removal of hydrogen, reducing the risk of hydrogen explosion. Furthermore, direct water cooling easily leads to condensation on the inner wall of the furnace tubes, causing oxidation of the metal powder and an increase in oxygen content. The air-cooling transition method helps maintain the dryness of the inner wall of the furnace tubes.

[0037] Furthermore, it also includes a control system 11, which controls the automated operation of the four-tube reduction furnace via a PLC; the PLC control system can precisely control the operating parameters of the equipment according to a preset program, realize automated production, and improve production efficiency and product quality.

[0038] Example 2, please refer to Figure 1-3 A method for hydrogen reduction, using a fully automated four-tube reduction furnace for hydrogen reduction, includes the following steps:

[0039] The material to be reduced is loaded into the upper boat 16 and the lower boat 17 by the automatic loading device 20 and placed on the graphite pad 18. After passing through the feeding system 2, the main furnace tube 6, the air-cooled furnace tube 7, the circulating water-cooled furnace tube 8, and the discharge system 9, it returns to the circulating rotary system 12. During this process, ambient temperature hydrogen is metered by the kiln tail atmosphere control system 13, heated by the heater 27, and then sent to the preheating hydrogen delivery device 15 and into the furnace. Protective gas nitrogen is metered by the kiln head atmosphere control system 14 and then sent into the furnace lining 5. The material passes through the main furnace tube, the air-cooled furnace tube, and the circulating water-cooled furnace tube in sequence before reaching the discharge system.

[0040] Furthermore, after the material reaches the discharge system 9, it returns to the circulating rotary system 12, is unloaded by the automatic unloading device 19, and is then loaded by the automatic loading device 20, repeating the entire cycle. In the prior art, manual feeding and unloading at the furnace head and tail increases the workload of workers and has a low level of intelligence. This application adopts the circulating rotary system 12 and automatic loading and unloading, which fully realizes fully automatic control and can achieve 24-hour uninterrupted loading and unloading. It can effectively improve production efficiency, reduce direct high-temperature contact and dust pollution, reduce human risks and safety accident rates under high-risk environmental conditions, and avoid boat displacement and jamming caused by manual placement, ensuring process consistency and a high level of intelligence.

[0041] refer to Figure 1 and Figure 2This fully automated four-tube reduction furnace for hydrogen reduction has the following dimensions: 22800mm*5642mm*2098mm, power: 500kw, maximum design temperature: 1150℃, maximum operating temperature: 1050℃, and the main furnace tube 6 has the following dimensions: 10000*540*170mm.

[0042] The main propulsion system's boat-pushing method is fully automatic pneumatic boat-pushing, with a boat-pushing time of 5-30 minutes, a hydrogen flow rate of 40-60 m³ / h, and a hydrogen pressure of 2-5 kPa.

[0043] Electrical components: standard electrical cabinet, main low-voltage electrical appliances, temperature control instruments, triggers, thermocouples, PLC.

[0044] For example, using the four-tube reduction furnace of this utility model, iron oxide powder is reduced by introducing hydrogen gas under a set temperature condition, and the main parameters of the resulting ultrafine iron powder are as follows: TFe%=99.2%, O%=0.42%, loose density: 1.4g / cm3, particle size D50=4.3um;

[0045] The production data obtained through the four-tube reduction furnace of this invention can achieve the following effects:

[0046] The utilization rate of hydrogen reached 88%, which is more than 70% higher than the traditional 17% utilization rate.

[0047] The main furnace tube 6 with a width of 540mm and a double-layer boat-shaped vessel is used, which increases the production capacity per unit time by 1.4 times compared with the traditional single-layer boat-shaped vessel with a width of 300mm.

[0048] Compared to traditional four-tube reduction furnaces, the reduction process temperature is reduced by about 30°C;

[0049] This invention provides a fully automated four-tube reduction furnace and method for hydrogen reduction. The furnace employs double-door sealing and a displacement chamber for both inlet and outlet, a graphite pad and double-layer boat design, preheats the hydrogen, uses a combination of air and water cooling, utilizes a circulating rotary track and automatic loading / unloading, and incorporates a hydrogen recovery device. This reduces hydrogen leakage and consumption, increases equipment capacity, improves reduction reaction efficiency and equipment lifespan, increases hydrogen utilization, ensures product consistency, and enhances the level of automation, effectively solving the problems in the prior art.

[0050] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0051] Obviously, the embodiments described above are only some embodiments of this utility model, not all embodiments. The accompanying drawings show preferred embodiments of this utility model, but do not limit the patent scope of this utility model. This utility model can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this utility model specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this utility model.

Claims

1. A fully automated four-tube reduction furnace for hydrogen reduction, characterized in that, It includes a main propulsion system (1), a feeding system (2), a main furnace tube (6), an air-cooled furnace tube (7), a circulating water-cooled furnace tube (8), and a discharge system (9) connected in sequence; The feeding system (2) is provided with an inner door (21) at the kiln head, an outer door (22) at the kiln head, and a kiln head replacement chamber (23), and the inner door (21) at the kiln head and the outer door (22) at the kiln head open and close alternately; the discharging system (9) is provided with an inner door (24) at the kiln tail, an outer door (25) at the kiln tail, and a kiln tail replacement chamber (26), and the inner door (24) at the kiln tail and the outer door (25) at the kiln tail open and close alternately to form a double-layer sealing structure; The fully automated four-tube reduction furnace also includes a control system (11), which controls the automated operation of the four-tube reduction furnace via a PLC.

2. The fully automated four-tube reduction furnace for hydrogen reduction according to claim 1, characterized in that, The feeding system (2) is fixed to the main furnace tube (6), air-cooled furnace tube (7), circulating water-cooled furnace tube (8), and discharge system (9) by means of flange connection.

3. The fully automated four-tube reduction furnace for hydrogen reduction according to claim 1, characterized in that, It also includes a support system (3), wherein the main push system (1) is connected to the feeding system (2) and fixed on the upper part of the support system (3).

4. The fully automated four-tube reduction furnace for hydrogen reduction according to claim 1, characterized in that, It also includes a furnace shell (4), a furnace lining (5), a kiln tail atmosphere control system (13), a kiln head atmosphere control system (14), and a preheating hydrogen delivery device (15). The furnace shell (4) and the furnace lining (5) are equipped with heaters (27). The ambient temperature hydrogen is metered by the kiln tail atmosphere control system (13), heated by the heaters (27), and then sent to the preheating hydrogen delivery device (15). The protective gas nitrogen is metered by the kiln head atmosphere control system (14) and then sent into the furnace lining (5).

5. The fully automated four-tube reduction furnace for hydrogen reduction according to claim 4, characterized in that, It also includes a hydrogen recovery back pressure system (10), which is connected to the hydrogen recovery and purification system; the main furnace tubes (6) are arranged in two vertical rows, with two tubes in each row; the hydrogen outlets of the four main furnace tubes (6) are collected and enter the hydrogen recovery and purification system after being connected to the hydrogen recovery back pressure system (10).

6. The fully automated four-tube reduction furnace for hydrogen reduction according to claim 5, characterized in that, It also includes a circulating rotary system (12), the feeding system (2) and the discharging system (9) are connected together with the circulating rotary system (12), and the circulating rotary system (12) is equipped with an automatic unloading device (19) and an automatic loading device (20).

7. The fully automated four-tube reduction furnace for hydrogen reduction according to claim 6, characterized in that, It also includes a double-layered boat, which consists of an upper boat (16), a lower boat (17), and a graphite pad (18) placed from top to bottom. The graphite pad (18) is placed on a circulating rotary system (12) to circulate between the automatic loading device (20), the feeding system (2), the main furnace tube (6), the air-cooled furnace tube (7), the circulating water-cooled furnace tube (8), the discharge system (9), and the automatic unloading device (19).

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