Reducing gas heating system and process for hydrogen metallurgy

Abstract

The invention belongs to the technical field of ferrous metallurgy, and relates to a reducing gas heating system and process for hydrogen metallurgy, the system comprises a heating furnace, a hydrogen-based shaft furnace, a decarburization device and gas connecting pipelines among the devices; the heating furnace is used for preheating reducing gas and supplying the reducing gas to the hydrogen-based shaft furnace; reaction gas generated by the hydrogen-based shaft furnace is decarbonized by a decarbonization device to generate reducing gas and decarbonized tail gas; a burner is arranged on the heating furnace and is respectively connected with decarburized tail gas, reaction gas and an external gas pipe; a decarburized tail gas preheater is arranged on a smoke exhaust pipe of the heating furnace; an outlet of the decarburized tail gas main pipe is respectively connected with a decarburized tail gas diffusing pipe and a decarburized tail gas burner supply pipe; a reducing gas pipeline is connected with the heating furnace; the decarburization tail gas burner supply pipe is connected with the decarburization tail gas preheater, and the preheated decarburization tail gas is supplied to a burner of the heating furnace. The byproduct gas in the hydrogen metallurgy process is fully utilized as the fuel of the heating furnace, the energy utilization efficiency is effectively improved, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel metallurgy, and relates to a reducing gas heating system and process for hydrogen metallurgy. BACKGROUND

[0002] Under the background of actively responding to climate change and vigorously promoting carbon emission reduction worldwide, the steel industry, as a key field of carbon emission, is facing great emission reduction pressure. A large amount of energy is consumed and a large amount of carbon dioxide is emitted in the steel production process, therefore, carbon emission reduction of the steel production process has become the core direction of future industry technology development. Among many low-carbon smelting technology paths, hydrogen metallurgy stands out with its significant emission reduction advantage and has become a research hotspot in the steel industry at home and abroad in recent years. Hydrogen metallurgy uses hydrogen as a reducing agent to replace traditional carbon-based reducing agents, which can greatly reduce carbon emissions in the steel production process and is of great significance to promote the green transformation of the steel industry. With the continuous deepening of research, a number of hydrogen metallurgy demonstration production lines have been launched at home and abroad. The construction of these production lines has accumulated valuable experience for the practical application of hydrogen metallurgy technology and further proved the feasibility and development potential of hydrogen metallurgy technology.

[0003] However, in the actual application process of hydrogen metallurgy process, energy utilization efficiency problem becomes the key factor restricting its large-scale promotion and cost reduction. Hydrogen metallurgy process involves multiple complex links, including hydrogen preparation, storage, transportation and efficient utilization in metallurgical reaction, etc., each link has an important influence on energy consumption. At present, the energy utilization efficiency of hydrogen metallurgy process still needs to be improved, there are problems such as energy waste, high energy consumption cost, etc.

[0004] In order to realize the sustainable development of hydrogen metallurgy technology, reduce its energy consumption cost and improve its market competitiveness, it is urgent to combine the process characteristics and actual needs of hydrogen metallurgy to comprehensively utilize and optimize the configuration of energy medium in the hydrogen metallurgy process. Through the development of new technologies and methods, the energy utilization efficiency of hydrogen metallurgy process is improved, the cascade utilization and efficient conversion of energy are realized, thereby laying a solid foundation for the wide application of hydrogen metallurgy technology. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a reducing gas heating system and process for hydrogen metallurgy to improve the energy utilization efficiency of hydrogen metallurgy process.

[0006] To achieve the above purpose, the present application provides the following technical scheme:

[0007] A reducing gas heating system for hydrogen metallurgy, comprising a heating furnace, a hydrogen-based shaft furnace, a decarburization device and a gas connection pipeline between each device.

[0008] The heating furnace is used to preheat the reducing gas, and the preheated reducing gas is supplied to the hydrogen-based vertical furnace to generate reaction gas;

[0009] The reaction gas generated by the hydrogen-based vertical furnace is decarbonized by the decarbonization device to produce reducing gas and decarbonized tail gas;

[0010] The heating furnace is provided with a burner, and the burner is connected to the decarbonized tail gas, the reaction gas and the external gas pipe respectively;

[0011] A decarbonization tail gas preheater is provided on the exhaust pipe of the heating furnace;

[0012] The hydrogen-based vertical furnace is connected to the decarbonization device and the burner respectively through a reaction gas pipeline;

[0013] The outlet of the decarbonization device is connected to a decarbonization tail gas main pipe and a reducing gas pipeline, the outlet of the decarbonization tail gas main pipe is respectively connected to a decarbonization tail gas vent pipe and a decarbonization tail gas burner supply pipe, and the reducing gas pipeline is connected to a heating furnace;

[0014] The decarburization tail gas burner supply pipe is connected to the decarburization tail gas preheater to preheat the decarburization tail gas, and the preheated decarburization tail gas is supplied to the burner of the heating furnace.

[0015] Furthermore, an air preheater is provided on the exhaust pipe of the heating furnace and is located upstream of the decarbonization tail gas preheater.

[0016] Furthermore, a decarbonization tail gas main pipe pressure gauge and a decarbonization tail gas main pipe flow meter are also provided on the decarbonization tail gas main pipe;

[0017] A decarbonization tail gas discharge pipe regulating valve is provided on the decarbonization tail gas discharge pipe, and a decarbonization tail gas supply pipe flow meter, a decarbonization tail gas supply pipe pressure regulating valve and a decarbonization tail gas pressure gauge are provided on the decarbonization tail gas burner supply pipe;

[0018] A reaction gas burner supply pipeline regulating valve is provided on the reaction gas pipeline connected to the burner;

[0019] An external gas supply pipe regulating valve is provided on the external gas pipe;

[0020] A reducing gas supplementary gas source pipeline is also provided on the heating furnace.

[0021] Furthermore, a cooling nitrogen pipeline is provided on the decarburization tail gas burner supply pipe at the upstream of the decarburization tail gas preheater, and a nitrogen purge pipe control valve is provided on the cooling nitrogen pipeline;

[0022] A nitrogen release pipe is provided on the decarburization tail gas burner supply pipe at the downstream of the decarburization tail gas preheater, and a nitrogen release pipe regulating valve is provided on the cooling nitrogen pipeline.

[0023] Furthermore, a bypass pipeline for bypassing the decarbonization tail gas preheater is provided on the exhaust pipe of the heating furnace, and a bypass flue gas pipeline valve is provided on the bypass pipeline;

[0024] The exhaust pipe is provided with a flue gas valve before the decarbonization tail gas preheater and a flue gas valve after the decarbonization tail gas preheater, which are located before and after the decarbonization tail gas preheater.

[0025] A reducing gas heating process for hydrogen metallurgy, using the reducing gas heating system, comprises the following steps:

[0026] The reducing gas is preheated by the heating furnace and then supplied to the hydrogen-based vertical furnace;

[0027] The reducing gas reacts in the hydrogen-based vertical furnace to generate reaction gas;

[0028] The reaction gas is decarbonized by the decarbonization device to produce reducing gas and decarbonized tail gas;

[0029] The decarbonized tail gas is preheated by the decarbonized tail gas preheater and then supplied to the burner of the heating furnace and / or discharged through the decarbonized tail gas discharge pipe.

[0030] Furthermore, the fuel combination of the burner in the heating furnace includes:

[0031] Simultaneously using the reaction gas and the decarbonized tail gas as fuel;

[0032] Simultaneously using the external coal gas and the decarbonized tail gas as fuel;

[0033] Alternatively, the reaction gas or the external coal gas may be used alone as fuel.

[0034] Furthermore, a decarbonization tail gas main pipe pressure gauge and a decarbonization tail gas main pipe flow meter are also provided on the decarbonization tail gas main pipe;

[0035] A decarbonization tail gas discharge pipe regulating valve is provided on the decarbonization tail gas discharge pipe, and a decarbonization tail gas supply pipe flow meter, a decarbonization tail gas supply pipe pressure regulating valve and a decarbonization tail gas pressure gauge are provided on the decarbonization tail gas burner supply pipe;

[0036] When the burner uses the decarbonized tail gas and the reaction gas or the external coal gas as fuel, when the pressure on the decarbonized tail gas main pipe fluctuates, the decarbonized tail gas supply pipe pressure regulating valve is adjusted to keep the decarbonized tail gas pressure in front of the burner stable.

[0037] Furthermore, the flow rate of the decarbonized tail gas main pipe is detected by the decarbonized tail gas main pipe flow meter, and the opening of the regulating valve of the decarbonized tail gas vent pipe is adjusted to maintain a stable flow rate of the decarbonized tail gas supplied to the burner;

[0038] Furthermore, in the flow rate and pressure control on the decarbonized tail gas supply pipe, priority is given to controlling the pressure to maintain stability, and secondly to controlling the flow rate to maintain stability.

[0039] Furthermore, in order to protect the decarbonization tail gas preheater, one of the following two solutions is adopted;

[0040] Solution 1: A cooling nitrogen pipeline is provided on the decarburization tail gas burner supply pipe upstream of the decarburization tail gas preheater, and a nitrogen purge pipe control valve is provided on the cooling nitrogen pipeline; a nitrogen release pipe is provided on the decarburization tail gas burner supply pipe downstream of the decarburization tail gas preheater, and a nitrogen release pipe regulating valve is provided on the cooling nitrogen pipeline;

[0041] When the burner does not use the decarburized tail gas as fuel, the nitrogen purge pipe control valve and the nitrogen release pipe regulating valve on the cooling nitrogen pipeline and the cooling nitrogen release pipeline are opened to pass nitrogen into the decarburized tail gas preheater for cooling protection; when the burner uses the decarburized tail gas as fuel, the valves on the cooling nitrogen pipeline and the cooling nitrogen release pipeline are closed;

[0042] Solution 2: A bypass pipe is provided on the exhaust pipe of the heating furnace to bypass the decarbonization tail gas preheater, and a bypass flue gas pipe valve is provided on the bypass pipe; and a flue gas valve before the decarbonization tail gas preheater and a flue gas valve after the decarbonization tail gas preheater are provided on the exhaust pipe.

[0043] When the heating furnace uses the decarbonized tail gas as fuel, the bypass flue gas pipeline valve of the bypass pipeline is closed, and the flue gas valve before the decarbonized tail gas preheater and the flue gas valve after the decarbonized tail gas preheater are opened to allow the flue gas to flow through the decarbonized tail gas preheater;

[0044] When the heating furnace does not use the decarbonized tail gas as fuel, the bypass flue gas pipeline valve of the bypass pipeline is opened, and the flue gas valve before the decarbonized tail gas preheater and the flue gas valve after the decarbonized tail gas preheater before and after the decarbonized tail gas preheater are closed to allow the flue gas to flow out through the bypass pipeline.

[0045] The beneficial effects of the present invention are:

[0046] The present invention provides a reducing gas heating system and process for hydrogen metallurgy. This system fully utilizes byproduct gases from the hydrogen metallurgical process—decarbonization exhaust and reaction gases—as heating furnace fuel, effectively improving energy efficiency and reducing production costs. By preheating the decarbonization exhaust gas before supplying it to the heating furnace for combustion, the system recovers waste heat and byproduct gases from the process, reducing reliance on external coal gas. This design not only saves energy but also reduces the economic burden of the production process, providing a sustainable energy solution for hydrogen metallurgical processes.

[0047] Another significant advantage of the system is its flexibility. The furnace supports a variety of fuel combinations, allowing it to operate with reaction gas or external coal gas alone, or mixed with decarbonized tail gas. This adaptability enables the system to adjust to production needs and energy availability, ensuring efficient operation under varying conditions. This flexible fuel selection further enhances the process's economic and practicality, meeting diverse industrial scenarios.

[0048] The stability of the system's operation is ensured by a sophisticated control mechanism. Pressure and flow detection devices installed on the decarburization tail gas main and supply pipes, combined with pressure regulating valves, enable real-time monitoring and adjustment of the tail gas supply to ensure stable delivery. This not only maintains the normal operation of the heating furnace but also ensures a constant preheating temperature for the reducing gas, thereby improving the reliability and efficiency of the entire hydrogen metallurgical process and providing solid technical support for industrial applications.

[0049] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0051] Figure 1 This is a schematic diagram of a reducing gas heating system for hydrogen metallurgy in Example 1;

[0052] Figure 2 This is a schematic diagram of a reducing gas heating system for hydrogen metallurgy in Example 2.

[0053] Reference numerals: heating furnace 1, hydrogen-based vertical furnace 2, decarbonization device 3, burner 4, reducing gas pipeline 5, reducing gas supplementary gas source pipeline 6, reaction gas pipeline 7, decarbonization tail gas main pipe 8, decarbonization tail gas main pipe flow meter 9, decarbonization tail gas discharge pipe 10, decarbonization tail gas discharge pipe regulating valve 11, decarbonization tail gas burner supply pipe 12, decarbonization tail gas supply pipe flow meter 13, decarbonization tail gas supply pipe pressure regulating valve 14, decarbonization tail gas Pressure gauge 15, nitrogen purge pipe 16, nitrogen purge pipe control valve 17, nitrogen release pipe 18, nitrogen release pipe regulating valve 19, external gas pipe 20, external gas supply pipe regulating valve 21, air preheater 22, decarbonization tail gas preheater 23, smoke exhaust pipe 24, decarbonization tail gas main pipe pressure gauge 25, decarbonization tail gas preheater front flue gas valve 26, decarbonization tail gas preheater rear flue gas valve 27, bypass flue gas pipeline valve 28. DETAILED DESCRIPTION

[0054] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0055] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0056] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0057] Example 1: Reducing gas heating system and process with nitrogen cooling protection

[0058] This embodiment provides a reducing gas heating system for hydrogen metallurgy, such as Figure 1 The system includes a heating furnace 1, a hydrogen-based vertical furnace 2, a decarbonization device 3, and gas connection pipelines between the devices. The reducing gas is preheated in the heating furnace 1 and supplied to the hydrogen-based vertical furnace 2. The reducing gas reacts in the hydrogen-based vertical furnace 2 to generate reaction gas. The reaction gas is decarbonized in the decarbonization device 3 to produce reducing gas and decarbonized tail gas. The specific design is as follows:

[0059] Heating Furnace 1: Used to preheat the reducing gas. The preheated reducing gas is transported to the hydrogen-based vertical furnace 2 via the reducing gas pipeline 5. Heating Furnace 1 is equipped with a burner 4, which is connected to the decarburization tail gas burner supply pipe 12, the reaction gas pipeline 7, and the external gas pipe 20 via pipelines to provide fuel. An air preheater 22 and a decarburization tail gas preheater 23 are installed in sequence on the exhaust pipe 24 of the heating furnace 1 to recover waste heat from the flue gas.

[0060] Hydrogen-based vertical furnace 2: Receives preheated reducing gas and reacts with the materials in the furnace to generate reaction gas. The reaction gas is transported to the decarbonization device 3 and the burner 4 through the reaction gas pipeline 7.

[0061] Decarburization unit 3 receives the reaction gas and decarburizes it, generating reducing gas and decarburized tail gas. The reducing gas is returned to the heating furnace 1 via reducing gas pipeline 5 for recycling. The decarburized tail gas is split through the decarburized tail gas main pipe 8. A portion is discharged through the decarburized tail gas vent pipe 10, and the remaining portion is sent through the decarburized tail gas burner supply pipe 12 to the decarburized tail gas preheater 23 for preheating before being supplied to the burner 4.

[0062] The decarbonization tail gas main pipe 8 is provided with a decarbonization tail gas main pipe pressure gauge 25 and a decarbonization tail gas main pipe flow meter 9 for monitoring pressure and flow.

[0063] A decarbonization tail gas discharging pipe regulating valve 11 is installed on the decarbonization tail gas discharging pipe 10 for regulating the emission amount.

[0064] The decarbonization tail gas burner supply pipe 12 is provided with a decarbonization tail gas supply pipe flow meter 13, a decarbonization tail gas supply pipe pressure regulating valve 14 and a decarbonization tail gas pressure gauge 15 for accurately controlling the fuel supply.

[0065] A reaction gas burner supply pipeline regulating valve (not numbered in the figure) is provided on the reaction gas pipeline 7 for connecting to the burner 4 , and an external gas supply pipeline regulating valve 21 is provided on the external gas pipe 20 .

[0066] The heating furnace 1 is also connected to a reducing gas supply pipeline 6 to replenish the reducing gas required by the system.

[0067] In order to protect the decarbonization tail gas preheater 23, a cooling nitrogen pipeline 16 (located upstream of the decarbonization tail gas preheater 23) and a nitrogen purge pipe control valve 17, as well as a nitrogen release pipe 18 (located downstream of the decarbonization tail gas preheater 23) and a nitrogen release pipe regulating valve 19 are provided on the decarbonization tail gas burner supply pipe 12 for cooling protection.

[0068] The reducing gas heating process of this embodiment is based on the above system, and the steps are as follows:

[0069] The reducing gas is preheated by the heating furnace 1 and then fed into the hydrogen-based vertical furnace 2.

[0070] The reducing gas reacts with the material in the hydrogen-based vertical furnace 2 to generate reaction gas.

[0071] The reaction gas enters the decarbonization device 3 and generates reducing gas and decarbonization tail gas after decarbonization treatment.

[0072] The decarbonized tail gas is preheated in the decarbonized tail gas preheater 23 and then sent to the burner 4 as fuel, or discharged through the decarbonized tail gas vent pipe 10.

[0073] Fuel Combination and Control

[0074] The fuel combination of burner 4 is flexible and can be selected:

[0075] The reaction gas and the decarbonization tail gas are used simultaneously;

[0076] External coal gas and decarbonized tail gas are used simultaneously;

[0077] Use reaction gas alone or external gas.

[0078] When using decarbonized tail gas as fuel, if the pressure in the decarbonized tail gas main pipe 8 fluctuates, the pressure upstream of the burner 4 is maintained stable by adjusting the decarbonized tail gas supply pipe pressure regulating valve 14. Simultaneously, the flow rate is monitored using the decarbonized tail gas main pipe flowmeter 9, and the opening of the decarbonized tail gas vent pipe regulating valve 11 is adjusted to ensure a stable fuel flow rate. During control, ensuring pressure stability takes precedence over ensuring flow stability.

[0079] To protect the decarbonization tail gas preheater 23:

[0080] When the burner 4 does not use the decarbonized tail gas, the nitrogen purge pipe control valve 17 and the nitrogen release pipe regulating valve 19 are opened to allow nitrogen to cool the preheater.

[0081] When burner 4 uses decarbonized tail gas, close the above valve to ensure normal preheating operation.

[0082] Example 2: Reducing gas heating system and process with bypass pipeline

[0083] This embodiment provides another reducing gas heating system for hydrogen metallurgy, such as Figure 2Compared with Example 1, the main difference lies in the protection method of the decarbonization tail gas preheater 23.

[0084] The basic structure of the system is the same as that of Example 1, including a heating furnace 1, a hydrogen-based vertical furnace 2, a decarbonization device 3 and related pipelines.

[0085] Differences: A bypass line is added to the exhaust pipe 24 of the heating furnace 1, bypassing the decarburization tail gas preheater 23. A bypass flue gas valve 28 is installed on the bypass line. The exhaust pipe 24 is also equipped with a flue gas valve 26 before the decarburization tail gas preheater and a flue gas valve 27 after the decarburization tail gas preheater, located before and after the decarburization tail gas preheater 23, respectively.

[0086] The process steps are the same as those in Example 1, except for the preheater protection method:

[0087] When the heating furnace 1 uses decarbonized tail gas as fuel, the bypass flue gas pipeline valve 28 is closed, and the flue gas valve 26 before the decarbonized tail gas preheater and the flue gas valve 27 after the decarbonized tail gas preheater are opened to allow the flue gas to flow through the decarbonized tail gas preheater 23 to fully utilize the waste heat.

[0088] When the heating furnace 1 does not use decarbonized tail gas, the bypass flue gas pipeline valve 28 is opened, and the flue gas valve 26 before the decarbonized tail gas preheater and the flue gas valve 27 after the decarbonized tail gas preheater are closed, so that the flue gas is discharged through the bypass pipeline to avoid overheating or fouling of the preheater.

[0089] This design protects the decarbonization tail gas preheater 23 by switching the flue gas flow direction, simplifies the nitrogen system, and is suitable for scenarios with long-term operation and low maintenance requirements.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A reducing gas heating system for hydrogen metallurgy, characterized in that: It includes heating furnace, hydrogen-based vertical furnace, decarburization device and gas connecting pipelines between the devices; The heating furnace is used to preheat the reducing gas, and the preheated reducing gas is supplied to the hydrogen-based vertical furnace to generate reaction gas; The reaction gas generated by the hydrogen-based vertical furnace is decarbonized by the decarbonization device to produce reducing gas and decarbonized tail gas; The heating furnace is provided with a burner, and the burner is connected to the decarbonized tail gas, the reaction gas and the external gas pipe respectively; A decarbonization tail gas preheater is provided on the exhaust pipe of the heating furnace; The hydrogen-based vertical furnace is connected to the decarbonization device and the burner respectively through a reaction gas pipeline; The outlet of the decarbonization device is connected to a decarbonization tail gas main pipe and a reducing gas pipeline, the outlet of the decarbonization tail gas main pipe is respectively connected to a decarbonization tail gas vent pipe and a decarbonization tail gas burner supply pipe, and the reducing gas pipeline is connected to a heating furnace; The decarburization tail gas burner supply pipe is connected to the decarburization tail gas preheater to preheat the decarburization tail gas, and the preheated decarburization tail gas is supplied to the burner of the heating furnace.

2. The reducing gas heating system according to claim 1, characterized in that: An air preheater is also provided on the exhaust pipe of the heating furnace and is located upstream of the decarbonization tail gas preheater.

3. The reducing gas heating system according to claim 1, characterized in that: A decarbonization tail gas main pipe pressure gauge and a decarbonization tail gas main pipe flow meter are also provided on the decarbonization tail gas main pipe; A decarbonization tail gas discharge pipe regulating valve is provided on the decarbonization tail gas discharge pipe, and a decarbonization tail gas supply pipe flow meter, a decarbonization tail gas supply pipe pressure regulating valve and a decarbonization tail gas pressure gauge are provided on the decarbonization tail gas burner supply pipe; A reaction gas burner supply pipeline regulating valve is provided on the reaction gas pipeline connected to the burner; An external gas supply pipe regulating valve is provided on the external gas pipe; A reducing gas supplementary gas source pipeline is also provided on the heating furnace.

4. The reducing gas heating system according to claim 1, characterized in that: A cooling nitrogen pipeline is provided on the decarburization tail gas burner supply pipe at the upstream of the decarburization tail gas preheater, and a nitrogen purge pipe control valve is provided on the cooling nitrogen pipeline; A nitrogen release pipe is provided on the decarburization tail gas burner supply pipe at the downstream of the decarburization tail gas preheater, and a nitrogen release pipe regulating valve is provided on the cooling nitrogen pipeline.

5. The reducing gas heating system according to claim 1, characterized in that: A bypass pipeline for bypassing the decarbonization tail gas preheater is provided on the exhaust pipe of the heating furnace, and a bypass flue gas pipeline valve is provided on the bypass pipeline; The exhaust pipe is provided with a flue gas valve before the decarbonization tail gas preheater and a flue gas valve after the decarbonization tail gas preheater, which are located before and after the decarbonization tail gas preheater.

6. A reducing gas heating process for hydrogen metallurgy, using the reducing gas heating system according to any one of claims 1 to 3, characterized in that: The process comprises the following steps: The reducing gas is preheated by the heating furnace and then supplied to the hydrogen-based vertical furnace; The reducing gas reacts in the hydrogen-based vertical furnace to generate reaction gas; The reaction gas is decarbonized by the decarbonization device to produce reducing gas and decarbonized tail gas; The decarbonized tail gas is preheated by the decarbonized tail gas preheater and then supplied to the burner of the heating furnace and / or discharged through the decarbonized tail gas discharge pipe.

7. The reducing gas heating process according to claim 6, characterized in that: The fuel combination of the burner in the heating furnace includes: Simultaneously using the reaction gas and the decarbonized tail gas as fuel; Simultaneously using the external coal gas and the decarbonized tail gas as fuel; Alternatively, the reaction gas or the external coal gas may be used alone as fuel.

8. The reducing gas heating process according to claim 7, characterized in that: A decarbonization tail gas main pipe pressure gauge and a decarbonization tail gas main pipe flow meter are also provided on the decarbonization tail gas main pipe; A decarbonization tail gas discharge pipe regulating valve is provided on the decarbonization tail gas discharge pipe, and a decarbonization tail gas supply pipe flow meter, a decarbonization tail gas supply pipe pressure regulating valve and a decarbonization tail gas pressure gauge are provided on the decarbonization tail gas burner supply pipe; When the burner uses the decarbonized tail gas and the reaction gas or the external coal gas as fuel, when the pressure on the decarbonized tail gas main pipe fluctuates, the decarbonized tail gas supply pipe pressure regulating valve is adjusted to keep the decarbonized tail gas pressure in front of the burner stable.

9. The reducing gas heating process according to claim 8, characterized in that: The flow rate of the decarbonized tail gas main pipe is detected by the decarbonized tail gas main pipe flow meter, and the opening of the regulating valve of the decarbonized tail gas vent pipe is adjusted to maintain a stable flow rate of the decarbonized tail gas supplied to the burner; Furthermore, in the flow rate and pressure control on the decarbonized tail gas supply pipe, priority is given to controlling the pressure to maintain stability, and secondly to controlling the flow rate to maintain stability.

10. The reducing gas heating process according to claim 6, characterized in that: In order to protect the decarbonization tail gas preheater, one of the following two solutions is adopted: Solution 1: A cooling nitrogen pipeline is provided on the decarburization tail gas burner supply pipe upstream of the decarburization tail gas preheater, and a nitrogen purge pipe control valve is provided on the cooling nitrogen pipeline; a nitrogen release pipe is provided on the decarburization tail gas burner supply pipe downstream of the decarburization tail gas preheater, and a nitrogen release pipe regulating valve is provided on the cooling nitrogen pipeline; When the burner does not use the decarbonized tail gas as fuel, the nitrogen purge pipe control valve and the nitrogen release pipe regulating valve on the cooling nitrogen pipeline and the cooling nitrogen release pipeline are opened to pass nitrogen into the decarbonized tail gas preheater for cooling protection; when the burner uses the decarbonized tail gas as fuel, the valves on the cooling nitrogen pipeline and the cooling nitrogen release pipeline are closed; Solution 2: A bypass pipe is provided on the exhaust pipe of the heating furnace to bypass the decarbonization tail gas preheater, and a bypass flue gas pipe valve is provided on the bypass pipe; and a flue gas valve before the decarbonization tail gas preheater and a flue gas valve after the decarbonization tail gas preheater are provided on the exhaust pipe. When the heating furnace uses the decarbonized tail gas as fuel, the bypass flue gas pipeline valve of the bypass pipeline is closed, and the flue gas valve before the decarbonized tail gas preheater and the flue gas valve after the decarbonized tail gas preheater are opened to allow the flue gas to flow through the decarbonized tail gas preheater; When the heating furnace does not use the decarbonized tail gas as fuel, the bypass flue gas pipeline valve of the bypass pipeline is opened, and the flue gas valve before the decarbonized tail gas preheater and the flue gas valve after the decarbonized tail gas preheater before and after the decarbonized tail gas preheater are closed to allow the flue gas to flow out through the bypass pipeline.

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