Shaft furnace sectional cooling and staged heat recovery system and method

Abstract

The present application provides a vertical furnace segmented cooling and staged heat recycling system and method, the vertical furnace segmented cooling and staged heat recycling system comprising: a vertical furnace having a reduction zone and a cooling zone from top to bottom; a feeding bin arranged at the top inlet of the vertical furnace and a cooler arranged at the bottom outlet of the vertical furnace; a first-stage cooling and heat recycling unit having a first gas supply pipe communicated with the lower part of the cooling zone and a first heat recovery pipe communicated with the upper part of the cooling zone and the upper part of the reduction zone; and a second-stage cooling and heat recycling unit having a second gas supply pipe communicated with the inlet of the cooler and a second heat recovery pipe communicated with the cooler and the feeding bin. The present application can solve the problem of insufficient heat recycling in the existing vertical furnace cooling system, resulting in energy waste.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, and in particular to a system and method for segmented cooling and graded heat recovery and utilization in a vertical furnace. Background Technology

[0002] Direct reduction (DRI) ironmaking in shaft furnaces is an important metallurgical process that uses reducing gases to reduce iron-containing raw materials to direct reduced iron (DRI) under solid conditions. It features low energy consumption, low pollution, and stable process operation, and is currently widely used. Typical gas-based shaft furnace processes include hydrogen-based processes using hydrogen as the main reducing agent, as well as the MIDREX and HYL processes, which primarily utilize natural gas reforming. During the shaft furnace reduction process, the temperature of DRI typically reaches 800–950°C, storing a large amount of sensible heat internally. To facilitate safe storage and transportation and prevent oxidation of the metallized iron surface, effective cooling is required before or after tapping.

[0003] There are two main types of cooling methods in existing technologies: one is an integrated vertical furnace design, where the furnace body consists of a preheating section, a reduction section, and a cooling section from top to bottom. At room temperature cooling gas enters the furnace from the bottom of the cooling section, directly contacting the high-temperature DRI for heat exchange, thus reducing its temperature to a suitable range. The cooling gas that has absorbed sensible heat is discharged from the top of the cooling section, cooled and then recycled. The other type is an independent cooler design, where the high-temperature DRI is transported to a closed cooler, where it is cooled by process reducing gas or inert gas.

[0004] However, the existing cooling systems generally lack heat recovery and utilization, resulting in significant energy loss. Therefore, it is necessary to develop an efficient heat recovery and utilization system and method to improve the overall energy efficiency of the vertical shaft furnace direct reduction ironmaking process. Summary of the Invention

[0005] The purpose of this invention is to provide a segmented cooling and graded heat recovery and utilization system and method for vertical furnaces, which solves the problem of insufficient heat recovery and utilization in existing vertical furnace cooling systems, leading to energy waste.

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

[0007] On one hand, the present invention provides a vertical shaft furnace segmented cooling and staged heat recovery and utilization system, which includes: A vertical furnace, which has a reduction zone and a cooling zone from top to bottom; A charging hopper is provided at the top inlet of the vertical furnace and a cooler is provided at the bottom outlet of the vertical furnace; A primary cooling and heat recovery unit, the primary cooling and heat recovery unit having a first air supply pipe connected to the lower part of the cooling zone, and a first heat recovery pipe connecting the upper part of the cooling zone and the upper part of the reduction zone; A secondary cooling and heat recovery unit, wherein the secondary cooling and heat recovery unit has a second air supply pipe connected to the inlet of the cooler, and a second heat recovery pipe connecting the cooler and the feeding hopper.

[0008] In a preferred embodiment of the present invention, the first gas supply pipe is filled with low-temperature hydrogen-rich reducing gas as the heat exchange circulation medium of the primary cooling and heat recovery unit; and / or, the second gas supply pipe is filled with low-temperature inert gas as the heat exchange circulation medium of the secondary cooling and heat recovery unit.

[0009] In a preferred embodiment of the present invention, the reduction zone comprises a preheating reduction zone and a high-temperature reduction zone from top to bottom, and one end of the first regenerating pipe is connected to the lower part of the preheating reduction zone.

[0010] In a preferred embodiment of the present invention, the vertical furnace is further provided with a high-temperature reducing gas inlet connected to the high-temperature reduction zone.

[0011] In a preferred embodiment of the present invention, a sealing valve is provided between the cooling zone of the vertical furnace and the cooler.

[0012] In a preferred embodiment of the present invention, an air seal structure is provided between the reduction zone and the cooling zone of the vertical furnace.

[0013] In a preferred embodiment of the present invention, a dust collector is provided on the first regenerating pipe.

[0014] Secondly, the present invention also provides a method for segmented cooling and graded heat recovery and utilization of a vertical furnace, comprising: The iron-containing furnace charge is fed into the upper part of the vertical furnace through the charging hopper, and at the same time, high-temperature reducing gas is sent into the middle part of the vertical furnace to reduce the iron-containing furnace charge in the reduction zone to generate direct reduced iron. Hydrogen-rich cooling gas is fed into the lower part of the vertical furnace to exchange heat countercurrently with the direct reduced iron in the cooling zone. After the heat exchange, the hydrogen-rich cooling gas is discharged from the cooling zone and introduced into the reduction zone to preheat and pre-reduce the iron-containing furnace charge. The direct reduced iron, after being cooled in the cooling zone, is subjected to secondary cooling in a cooler. At the same time, the inert gas that has undergone secondary heat exchange with the direct reduced iron in the cooler is introduced into the charging hopper to dry and preheat the iron-containing furnace charge.

[0015] In a preferred embodiment of the present invention, a gas seal structure is provided between the cooling zone and the reduction zone, and the hydrogen-rich cooling gas after heat exchange in the cooling zone is discharged from the upper part of the cooling zone by pressure difference control.

[0016] In a preferred embodiment of the present invention, a sealing valve is provided between the cooler and the cooling zone, and the isolation of the inert gas in the cooler from the atmosphere inside the vertical furnace is achieved by pressure differential control.

[0017] In a preferred embodiment of the present invention, the reduction zone comprises a preheating reduction zone and a high-temperature reduction zone from top to bottom, and the hydrogen-rich cooling gas exported from the cooling zone is introduced into the preheating reduction zone to preheat and pre-reduce the iron-containing furnace charge.

[0018] Compared with the prior art, the technical solution of the present invention has the following characteristics and advantages: 1. Achieve efficient and phased heat recovery.

[0019] Low-temperature hydrogen-rich reducing gas is used to recover waste heat from high-temperature direct reduced iron in the cooling zone. The heated hydrogen-rich reducing gas is then used for preheating and pre-reduction of the furnace charge, achieving cascade utilization of high-grade sensible heat. Simultaneously, low-temperature inert gas in the cooler is used to recover secondary waste heat from the first-cooled direct reduced iron. The heated inert gas is then introduced into the charging hopper at the top of the vertical furnace for drying and preheating of the furnace charge, achieving cascade utilization of low-grade sensible heat. Overall, this improves energy efficiency and reduces production energy consumption.

[0020] 2. Maintain thermal balance and atmosphere stability in the high-temperature reduction zone.

[0021] By setting up an air seal structure between the cooling zone and the high-temperature reduction zone and controlling the pressure difference, the inert gas used as secondary cooling gas is prevented from entering the high-temperature reduction zone, effectively avoiding the temperature drop in the reduction zone, thereby ensuring the efficient reduction reaction of the furnace charge and the quality of the product.

[0022] 3. Improve security and system stability.

[0023] The two-stage cooling and heat recovery unit design reduces the discharge temperature of high-temperature direct reduced iron, reduces the risk of oxidation, and ensures the safe and stable operation of storage, transportation, and subsequent processing. Attached Figure Description

[0024] 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: 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.

[0025] Figure 1 This is a schematic diagram of the vertical furnace segmented cooling and graded heat recovery and utilization system described in this invention.

[0026] Explanation of reference numerals in the attached figures: 10. Vertical shaft furnace; 11. Charging hopper; 12. Cooler; 13. High-temperature reducing gas inlet; 14. Nitrogen cooling gas inlet; 15. Nitrogen cooling gas outlet; 16. Low-temperature reducing gas inlet; 17. High-temperature reducing gas outlet; 18. Upper gas inlet; 20. First gas supply pipe; 21. First heat recovery pipe; 22. Second gas supply pipe; 23. Second heat recovery pipe; 24. Dust collector. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Implementation Method 1: This invention provides a vertical shaft furnace segmented cooling and graded heat recovery and utilization system, such as... Figure 1 As shown, it includes: a vertical furnace 10, which has a reduction zone and a cooling zone from top to bottom; a feeding hopper 11 located at the top inlet of the vertical furnace 10 and a cooler 12 located at the bottom outlet of the vertical furnace 10; a primary cooling and heat recovery unit, which has a first gas supply pipe 20 connected to the lower part of the cooling zone and a first regenerating pipe 21 connecting the upper part of the cooling zone and the upper part of the reduction zone; and a secondary cooling and heat recovery unit, which has a second gas supply pipe 22 connected to the inlet of the cooler 12 and a second regenerating pipe 23 connecting the cooler 12 and the feeding hopper 11.

[0031] The vertical shaft furnace segmented cooling and graded heat recovery system of the present invention utilizes low-temperature hydrogen-rich reducing gas to recover waste heat from high-temperature direct reduced iron in the cooling zone within the primary cooling and heat recovery unit. The heated hydrogen-rich reducing gas is then used for preheating and pre-reduction of the furnace charge, achieving tiered utilization of high-grade sensible heat. Simultaneously, in the secondary cooling and heat recovery unit, low-temperature inert gas in the cooler 12 is used for secondary waste heat recovery from the first-cooled direct reduced iron. The heated inert gas is then introduced into the charging hopper 11 at the top of the vertical shaft furnace 10 for drying and preheating of the furnace charge, achieving tiered utilization of low-grade sensible heat. This overall improves energy efficiency and reduces production energy consumption.

[0032] Meanwhile, the design of the two-stage cooling and heat recovery unit reduces the discharge temperature of high-temperature direct reduced iron, reduces the risk of oxidation, and ensures the safe and stable operation of storage, transportation and subsequent processing.

[0033] The following section will describe in detail the specific structure of each part of the vertical furnace segmented cooling and graded heat recovery and utilization system described in this invention, as well as the position and pipeline connection relationship between each part.

[0034] The vertical shaft furnace segmented cooling and graded heat recovery system is based on the production of direct reduced iron in vertical shaft furnace 10, such as... Figure 1 As shown, it has a vertical furnace 10, the top of which is the feed inlet, and a material distribution system is connected to the feed inlet. The bottom of the vertical furnace 10 is the discharge outlet, and a two-stage cooling system is connected to the discharge outlet.

[0035] The main structure of the feeding system is the feeding bin 11, which stores iron-containing furnace charge (pretreated iron oxide ore). After the feeding bin 11 completes the pressure equalization operation, it can feed the iron-containing furnace charge into the upper part of the vertical furnace 10.

[0036] Based on the different stages within the vertical shaft furnace 10, the internal space of the vertical shaft furnace 10 can be divided into a reduction zone and a cooling zone from top to bottom. In the reduction zone, the iron-containing furnace charge undergoes a reduction reaction with the reducing agent (hydrogen) to produce elemental iron (direct reduced iron). In the cooling zone, the direct reduced iron produced by the reaction can be cooled in various ways to prevent it from being oxidized again after being taken out of the furnace.

[0037] The main structure of the two-stage cooling system is the cooler 12, which contains a cooling medium. The cooler 12 is connected to the outlet at the bottom of the vertical furnace 10. The direct reduced iron produced by the vertical furnace 10 can be further cooled after entering the cooler 12.

[0038] The vertical furnace segmented cooling and graded heat recovery system has two-stage cooling and heat recovery units, namely a primary cooling and heat recovery unit and a secondary cooling and heat recovery unit, which are used to realize segmented cooling and graded heat recovery.

[0039] like Figure 1 As shown, the primary cooling and heat recovery unit has a first gas supply pipe 20 and a first heat recovery pipe 21. A low-temperature reducing gas inlet 16 is provided on the lower shell of the cooling zone of the vertical furnace 10. One end of the first gas supply pipe 20 is connected to the low-temperature reducing gas inlet 16 to allow the heat exchange circulating medium to enter the cooling zone. The heat exchange circulating medium entering the cooling zone cools the direct reduced iron, thereby lowering its temperature. A high-temperature reducing gas outlet 17 is provided on the upper shell of the cooling zone of the vertical furnace 10. The inlet end of the first heat recovery pipe 21 is connected to the high-temperature reducing gas outlet 17, allowing the heat exchange circulating medium, after being heated through heat exchange in the cooling zone, to enter the first heat recovery pipe 21. The upper part of the shell of the reduction zone of the vertical furnace 10 is provided with an upper air inlet 18. The outlet end of the first reheat pipe 21 is connected to the upper air inlet 18. The high-temperature heat exchange circulation medium in the first reheat pipe 21 can re-enter the vertical furnace 10 through the upper air inlet 18 and come into contact with the falling iron-containing furnace charge in the upper reduction zone, thereby preheating and pre-reducing the iron-containing furnace charge. Then it is discharged from the top of the furnace, thus making full use of the high-grade heat.

[0040] like Figure 1As shown, the secondary cooling and heat recovery unit has a second gas supply pipe 22 and a second heat recovery pipe 23. A nitrogen cooling gas inlet 14 is provided at the lower part of the cooler 12, and one end of the second gas supply pipe 22 is connected to the nitrogen cooling gas inlet 14 to introduce the heat exchange circulating medium into the cooler 12. Inside the cooler 12, the heat exchange circulating medium can perform secondary cooling on the direct reduced iron entering the cooler 12 to further reduce its temperature. A nitrogen cooling gas outlet 15 is provided at the upper part of the cooler 12, and the inlet end of the second heat recovery pipe 23 is connected to the nitrogen cooling gas outlet 15. The heat exchange circulating medium, after being heated by heat exchange within the cooler 12, can enter the second heat recovery pipe 23. The charging hopper 11 at the top of the vertical furnace 10 is equipped with an air inlet. The outlet end of the second reheat pipe 23 is connected to the air inlet of the charging hopper 11. The high-temperature heat exchange circulation medium in the second reheat pipe 23 can enter the charging hopper 11 through the air inlet and come into contact with the iron-containing furnace charge in the charging hopper 11, thereby drying and preheating the iron-containing furnace charge, thus making full use of the medium and low grade heat.

[0041] Through the above-mentioned cooling and heat recovery process, the segmented cooling and graded heat recovery of high-temperature direct reduced iron are achieved. The high-grade heat is used for the preheating and pre-reduction of the iron-containing furnace charge in the upper part of the vertical furnace 10, while the medium and low-grade heat is used for the drying and preheating of the iron-containing furnace charge in the charging hopper 11. This not only improves energy utilization efficiency and reduces the consumption of reducing gas and electricity, but also ensures the stability of the atmosphere in the reduction zone and the quality of the product. At the same time, it improves the safety and stability of the charging and storage of the furnace charge.

[0042] The structure and technical effects of the preferred embodiment of the vertical furnace segmented cooling and graded heat recovery and utilization system of the present invention will be further described below.

[0043] According to one embodiment of the present invention, a low-temperature hydrogen-rich reducing gas is passed through the first gas supply pipe 20 as the heat exchange circulation medium of the primary cooling and heat recovery unit; a low-temperature inert gas is passed through the second gas supply pipe 22 as the heat exchange circulation medium of the secondary cooling and heat recovery unit, and the inert gas is nitrogen, which is commonly used in the chemical industry, as the heat exchange circulation medium of the secondary cooling.

[0044] According to one embodiment of the present invention, the reduction zone has a preheating reduction zone and a high-temperature reduction zone from top to bottom. One end of the first reheat pipe 21 is connected to the lower part of the preheating reduction zone. The hydrogen-rich reducing gas after heat exchange and heating is introduced into the preheating reduction zone and comes into countercurrent contact with the iron-containing furnace charge for preheating and pre-reduction of the iron-containing furnace charge.

[0045] Furthermore, such as Figure 1As shown, the vertical furnace 10 is also provided with a high-temperature reducing gas inlet 13 connected to the high-temperature reduction zone. The high-temperature reducing gas inlet 13 is connected to a high-temperature reducing gas source. The high-temperature reducing gas enters the high-temperature reduction zone and comes into countercurrent contact with the iron-containing furnace charge to undergo a reduction reaction. The main reduction process of the iron-containing furnace charge is carried out in the high-temperature reduction zone. The flue gas generated by the high-temperature reducing gas after the reaction is discharged from the top outlet of the vertical furnace 10.

[0046] According to one embodiment of the present invention, a sealing valve is provided between the cooling zone of the vertical furnace 10 and the cooler 12; by providing the sealing valve and using differential pressure control measures during operation, the nitrogen in the cooler 12 is effectively isolated from the internal atmosphere of the vertical furnace 10, thereby preventing nitrogen from entering the cooling zone or causing leakage of hydrogen-rich gas.

[0047] According to one embodiment of the present invention, a gas seal structure is provided between the reduction zone and the cooling zone of the vertical furnace 10; by setting the gas seal structure and controlling the pressure difference during operation, the gas after heat exchange in the cooling zone is smoothly discharged from the upper part of the cooling zone to prevent it from entering the high-temperature reduction zone, thereby avoiding the temperature drop in the reduction zone caused by low-temperature gas, thus ensuring the stability of the reduction reaction rate and metallization rate, and ensuring the stability of product quality.

[0048] According to one embodiment of the present invention, such as Figure 1 As shown, a dust collector 24 is installed on the first reheat pipe 21; the hydrogen-rich reducing gas that has been in contact with the direct reduced iron in the cooling zone is treated to remove dust before being introduced into the preheating reduction zone, thereby avoiding pipe blockage and reducing impurities in the material.

[0049] Implementation Method Two: The present invention also provides a method for segmented cooling and graded heat recovery and utilization of a vertical furnace, which includes the following steps: Step S1: The iron-containing furnace charge is fed into the upper part of the vertical furnace 10 through the charging hopper 11, and at the same time, high-temperature reducing gas is sent into the middle part of the vertical furnace 10 to reduce the iron-containing furnace charge in the reduction zone to generate direct reduced iron.

[0050] Step S2: The hydrogen-rich cooling gas is fed into the lower part of the vertical furnace 10 to exchange heat with the direct reduced iron in the cooling zone in a countercurrent manner. After the heat exchange, the hydrogen-rich cooling gas is discharged from the cooling zone and introduced into the reduction zone to preheat and pre-reduce the iron-containing furnace charge.

[0051] Step S3: The direct reduced iron cooled in the cooling zone is cooled a second time through the cooler 12. At the same time, the inert gas in the cooler 12 after the second heat exchange with the direct reduced iron is introduced into the charging hopper 11 to dry and preheat the iron-containing furnace charge.

[0052] The vertical shaft furnace segmented cooling and graded heat recovery and utilization method of the present invention first uses low-temperature hydrogen-rich reducing gas (i.e., the hydrogen-rich cooling gas mentioned above) to recover waste heat from high-temperature direct reduced iron in the cooling zone. Then, the heated hydrogen-rich reducing gas is used for preheating and pre-reduction of the furnace charge, realizing the cascade utilization of high-grade sensible heat. Next, the low-temperature inert gas in the cooler 12 is used for secondary heat exchange and waste heat recovery of the direct reduced iron after primary cooling. Then, the heated inert gas is introduced into the charging hopper 11 at the top of the vertical shaft furnace 10 for drying and preheating of the furnace charge, realizing the cascade utilization of medium and low-grade sensible heat, improving overall energy utilization efficiency and reducing production energy consumption.

[0053] Meanwhile, the two-stage cooling and heat recovery process design significantly reduces the discharge temperature of high-temperature direct reduced iron, reduces the risk of oxidation, and ensures the safe and stable operation of storage, transportation, and subsequent processing.

[0054] It should be noted that the above steps are described in sequence according to the process of the iron-containing furnace charge falling in the vertical furnace. In actual production, the ironmaking process in the vertical furnace is a continuous process, and the above steps are all carried out simultaneously.

[0055] The following section will provide a detailed description of the specific process steps of the vertical furnace segmented cooling and graded heat recovery and utilization method described in this invention.

[0056] In step S1, the feeding and reduction processes are carried out.

[0057] Iron-containing furnace charge is fed into the upper part of the vertical shaft furnace 10 via the charging hopper 11. High-temperature reducing gas enters the middle part of the vertical shaft furnace 10 through the high-temperature reducing gas inlet 13, maintaining a stable atmosphere and temperature field in the reduction zone and providing the necessary heat and reducing agent for the reduction of the furnace charge. The iron-containing furnace charge forms a continuous column of charge falling from top to bottom, and undergoes a reduction reaction with the high-temperature reducing gas in the reduction zone to produce high-temperature direct reduced iron. The temperature of the furnace charge exiting the reduction zone is approximately 800℃~950℃.

[0058] In step S2, the first stage of cooling (hydrogen-rich gas countercurrent heat exchange) and high-grade heat recovery and reuse process are carried out.

[0059] Room-temperature hydrogen-rich gas, used as cooling gas, enters the lower cooling zone of the vertical shaft furnace 10 through the low-temperature reducing gas inlet 16. It flows upwards and exchanges heat counter-currently with the high-temperature direct reduced iron from the high-temperature reduction zone, reducing the outlet temperature of the furnace charge to approximately 200°C to 400°C. The heat-exchanged hydrogen-rich gas is then directly introduced into the upper inlet 18 of the vertical shaft furnace 10, using the recovered high-grade sensible heat for preheating and pre-reduction of the upper furnace charge, thus improving thermal efficiency. Preferably, the heat-exchanged hydrogen-rich gas can be dust-removed before being introduced into the upper inlet 18 of the vertical shaft furnace 10 to avoid pipe blockage and reduce impurities in the material.

[0060] In step S3, a second-stage cooling (nitrogen countercurrent heat exchange) and low-grade heat recovery and reuse process are carried out.

[0061] Nitrogen cooling gas enters cooler 12 through nitrogen cooling gas inlet 14, flows upwards, and exchanges heat counter-currently with the direct reduced iron after the first stage of cooling, further reducing the furnace charge temperature to 60℃~80℃. The nitrogen gas temperature after heat exchange is approximately 200℃~400℃, and it is orderly discharged through nitrogen cooling gas outlet 15 at the top of cooler 12. The nitrogen gas after the second stage of heat exchange is transported through pipelines to the charging hopper 11 of the charging system, transferring the medium and low grade sensible heat it carries to the iron-containing furnace charge, achieving the drying and preheating of the iron-containing furnace charge. Finally, the treated nitrogen gas returns to the nitrogen circulation loop to continue participating in the second stage of cooling process.

[0062] The following will further explain the process and technical effects of the preferred embodiment of the vertical furnace segmented cooling and graded heat recovery and utilization method of the present invention.

[0063] According to one embodiment of the present invention, a gas seal structure is provided between the cooling zone and the reduction zone, and the hydrogen-rich cooling gas after heat exchange in the cooling zone is discharged from the upper part of the cooling zone by pressure difference control, so as to maintain a stable flow direction of the hydrogen-rich cooling gas from bottom to top, and ensure that the gas after heat exchange (about 400°C to 750°C) is discharged in an orderly manner through the high-temperature reducing gas outlet 17 at the bottom of the vertical furnace 10, avoiding backflow to the high-temperature reduction zone.

[0064] According to one embodiment of the present invention, a sealing valve is provided between the cooler 12 and the cooling zone, and the inert gas in the cooler 12 is isolated from the internal atmosphere of the vertical furnace 10 by pressure differential control, so as to prevent nitrogen from entering the body of the vertical furnace 10 and diluting the reducing gas.

[0065] According to one embodiment of the present invention, the reduction zone comprises a preheating reduction zone and a high-temperature reduction zone from top to bottom. Hydrogen-rich cooling gas extracted from the cooling zone is introduced into the preheating reduction zone to preheat and pre-reduce the iron-containing furnace charge. Since the heat of the hydrogen-rich cooling gas after heat exchange in the cooling zone is slightly insufficient compared to the heat of the high-temperature reducing gas directly introduced into the high-temperature reduction zone, it is introduced into the preheating reduction zone for preheating and pre-reduction, thereby ensuring the high-temperature environment in the high-temperature reduction zone and ensuring the efficient reduction reaction and product quality of the iron-containing furnace charge in the high-temperature reduction zone.

[0066] 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 segmented cooling and graded heat recovery system for a vertical shaft furnace, characterized in that, include: A vertical furnace (10) having a reduction zone and a cooling zone from top to bottom; A feeding hopper (11) is provided at the top inlet of the vertical furnace (10) and a cooler (12) is provided at the bottom outlet of the vertical furnace (10). A primary cooling and heat recovery unit, the primary cooling and heat recovery unit having a first air supply pipe (20) connected to the lower part of the cooling zone, and a first heat recovery pipe (21) connecting the upper part of the cooling zone and the upper part of the reduction zone. The secondary cooling and heat recovery unit has a second air supply pipe (22) connected to the inlet of the cooler (12) and a second heat recovery pipe (23) connecting the cooler (12) and the feeding hopper (11).

2. The vertical furnace segmented cooling and graded heat recovery system according to claim 1, characterized in that, The first gas supply pipe (20) is filled with low-temperature hydrogen-rich reducing gas as the heat exchange circulation medium of the first-stage cooling and heat recovery unit; and / or, the second gas supply pipe (22) is filled with low-temperature inert gas as the heat exchange circulation medium of the second-stage cooling and heat recovery unit.

3. The vertical furnace segmented cooling and graded heat recovery system according to claim 1 or 2, characterized in that, The reduction zone consists of a preheating reduction zone and a high-temperature reduction zone from top to bottom, and one end of the first regenerating pipe (21) is connected to the lower part of the preheating reduction zone.

4. The vertical shaft furnace segmented cooling and graded heat recovery system according to claim 3, characterized in that, The vertical furnace (10) is also provided with a high-temperature reducing gas inlet (13) connected to the high-temperature reducing zone.

5. The vertical shaft furnace segmented cooling and graded heat recovery system according to claim 1, characterized in that, A sealing valve is provided between the cooling zone of the vertical furnace (10) and the cooler (12).

6. The vertical shaft furnace segmented cooling and graded heat recovery system according to claim 1, characterized in that, An air seal structure is provided between the reduction zone and the cooling zone of the vertical furnace (10).

7. The vertical furnace segmented cooling and graded heat recovery system according to claim 1, characterized in that, A dust collector (24) is provided on the first heat recovery pipe (21).

8. A method for segmented cooling and graded heat recovery and utilization of a vertical shaft furnace, characterized in that, include: Iron-containing furnace charge is fed into the upper part of the vertical furnace (10) through the charging bin (11), and high-temperature reducing gas is sent into the middle part of the vertical furnace (10) to reduce the iron-containing furnace charge to generate direct reduced iron in the high-temperature reduction zone. Hydrogen-rich cooling gas is fed into the lower part of the vertical furnace (10) to exchange heat with the direct reduced iron in the cooling zone in a countercurrent manner. Then, the hydrogen-rich cooling gas after heat exchange is exported from the cooling zone and introduced into the preheating reduction zone above the high-temperature reduction zone to preheat and pre-reduce the iron-containing furnace charge. The direct reduced iron, after being cooled in the cooling zone, is subjected to secondary cooling through a cooler (12). At the same time, the inert gas that has undergone secondary heat exchange with the direct reduced iron in the cooler (12) is introduced into the charging hopper (11) to dry and preheat the iron-containing furnace charge.

9. The method for segmented cooling and graded heat recovery and utilization of a vertical furnace according to claim 8, characterized in that, A gas seal structure is provided between the cooling zone and the reduction zone, and the hydrogen-rich cooling gas after heat exchange in the cooling zone is discharged from the upper part of the cooling zone by pressure difference control.

10. The method for segmented cooling and graded heat recovery and utilization of a vertical furnace according to claim 8, characterized in that, A sealing valve is installed between the cooler (12) and the cooling zone, and the inert gas in the cooler (12) is isolated from the atmosphere inside the vertical furnace (10) by pressure differential control.

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