Multi-stage heat recovery system

Abstract

This invention provides a multi-stage heat recovery system connected between an electric furnace and a dust removal system. The multi-stage heat recovery system includes: a conveying flue with its inlet connected to the electric furnace and its outlet connected to the dust removal system; a waste heat utilization unit having interconnected multi-stage heat exchange modules and a steam drum for containing steam, the multi-stage heat exchange modules being arranged at the outlet of the conveying flue; and a heat storage collection unit having interconnected heat storage modules and a heat storage tank for storing heat storage medium, the heat storage modules being arranged in the conveying flue. This multi-stage heat recovery system solves the problem of fluctuating production in smelting flue gas in the field of high-temperature flue gas recovery technology, while simultaneously improving the heat recovery efficiency of smelting flue gas and providing various heat absorption products.

Description

Technical Field

[0001] This invention relates to the field of high-temperature flue gas recovery technology, and in particular to a multi-stage heat recovery system. Background Technology

[0002] The description in this section provides only background information related to the disclosure of this invention and does not constitute prior art.

[0003] In recent years, energy conservation throughout the entire steel production process has become a key technological requirement for the steel industry. The demand for energy conservation and carbon reduction throughout the entire process is growing. Among them, the most prominent problem in the electric arc furnace steelmaking process is the large temperature fluctuation of the smelting flue gas, which results in extremely low waste heat recovery efficiency. The sensible heat of the smelting flue gas at around 1000 degrees Celsius can only provide a small amount of qualified low-pressure saturated steam after passing through the vaporization waste heat boiler and accumulator. Moreover, the production efficiency of this steam is low, resulting in a low level of waste heat utilization efficiency for smelting flue gas.

[0004] Existing technical solutions include the use of various steam structures to cope with the temperature fluctuations of smelting flue gas, or the use of dual-working-fluid heat exchange to improve the heat recovery efficiency of smelting flue gas at high temperature peaks, hoping to avoid the waste of high-temperature waste heat. However, the heat absorption capacity of these technical solutions is relatively low, and they do not substantially solve the problem of complete absorption and utilization of waste heat. The final product provided by these technical solutions is still only low-pressure saturated steam, with a single product use and no other product utilization options, resulting in the heat recovery efficiency of waste heat utilization remaining at a low level.

[0005] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-stage heat recovery system that solves the problem of fluctuating production of smelting flue gas in the field of high-temperature flue gas recovery technology, while improving the heat recovery efficiency of smelting flue gas and providing a variety of heat absorption products.

[0007] The above-mentioned objectives of this invention are mainly achieved by the following technical solutions:

[0008] This invention provides a multi-stage heat recovery system connected between an electric furnace and a dust removal system, the multi-stage heat recovery system comprising:

[0009] The flue is connected to the electric furnace at its inlet and to the dust removal system at its outlet.

[0010] The waste heat utilization unit has interconnected multi-stage heat exchange modules and a steam drum for containing steam, with the multi-stage heat exchange modules arranged at the outlet of the conveying flue.

[0011] The heat storage and collection unit has a heat storage module connected to it and a heat storage tank for storing the heat storage medium. The heat storage module is arranged in the conveying flue.

[0012] In one specific embodiment, the heat storage module has a high-temperature medium heat exchange module, which is arranged at the outlet of the conveying flue, and the heat storage tank has a first heat storage tank, which is connected to the high-temperature medium heat exchange module.

[0013] In one specific embodiment, the heat storage tank has a second heat storage tank connected to the first heat storage tank. The outlet of the first heat storage tank is connected to the inlet of the high-temperature medium heat exchange module through a first injection pipeline, and the outlet of the high-temperature medium heat exchange module is connected to the inlet of the second heat storage tank through a first output pipeline.

[0014] In one specific embodiment, a recovery pipeline is connected to the first output pipeline, and the recovery pipeline is connected to the inlet of the first thermal storage tank.

[0015] In one specific embodiment, the heat storage module further includes an initial state heat storage module, which is arranged at the inlet of the conveying flue and connected to the first output pipeline.

[0016] In one specific embodiment, an internal circulation pipeline is connected between the first injection pipeline and the first output pipeline.

[0017] In one specific embodiment, a heat exchange module is connected between the second heat storage tank and the first heat storage tank, and the heat exchange module is connected to the multi-stage heat exchange module through heat exchange pipelines.

[0018] In one specific embodiment, the multi-stage heat exchange module has at least a primary heat exchange module and a secondary heat exchange module spaced apart along the axial direction of the conveying flue, the primary heat exchange module and the secondary heat exchange module being respectively connected to the steam drum, and the high-temperature medium heat exchange module being located between the primary heat exchange module and the secondary heat exchange module.

[0019] In one specific embodiment, the heat exchange area of ​​the primary heat exchange module and the heat exchange area of ​​the secondary heat exchange module decrease sequentially along the direction toward the outlet of the conveying flue.

[0020] In one specific embodiment, the initial state heat storage module has an inner spiral pipe and an outer spiral pipe connected to each other, and the outer spiral pipe is sleeved on the outside of the inner spiral pipe.

[0021] In one specific embodiment, the heat storage and collection unit further includes a protective gas input pipe, and a balancing pipeline is connected between the first heat storage tank and the second heat storage tank, with the protective gas input pipe connected to the balancing pipeline.

[0022] Compared with the prior art, the technical solution of the present invention has the following characteristics and advantages:

[0023] 1. This invention can improve the thermal energy quality of flue gas waste heat recovery products by setting up multiple waste heat utilization units, further improve heat recovery efficiency, and produce higher quality heat sources.

[0024] 2. This invention enables more flexible utilization of waste heat recovery products from flue gas through a heat storage collection unit. At the same time, the high-quality heat source energy stored in this circulating energy storage unit can be applied to a wider range of industrial production and can be further combined with various other industrial heat production systems, such as for the production of saturated steam, superheated steam, hot water, etc.

[0025] 3. At the same time, the heat storage and collection unit set in this invention can better cope with the fluctuation of waste heat of flue gas, ensure the stability of flue gas heating, and enable the smelting flue gas heating system to be stably connected to the industrial heating system. Attached Figure Description

[0026] Figure 1 This is a pipeline diagram of a first embodiment of the multi-stage heat recovery system of the present invention;

[0027] Figure 2 This is a pipeline diagram of a second embodiment of the multi-stage heat recovery system of the present invention;

[0028] Figure 3 This is a cross-sectional view of the initial state heat storage module of the multi-stage heat recovery system of the present invention;

[0029] Figure 4 This is a top view of the initial state heat storage module of the multi-stage heat recovery system of the present invention.

[0030] Explanation of icon numbers:

[0031] 1. Conveying flue; 11. First flue section; 12. Second flue section; 13. Third flue section;

[0032] 2. Waste heat utilization unit; 21. Multi-stage heat exchange module; 211. Primary heat exchange module; 212. Secondary heat exchange module; 22. Steam drum; 23. Conveying pipeline; 24. Gas collection pipeline;

[0033] 3. Heat storage and collection unit; 31. Heat storage module; 311. High-temperature medium heat exchange module; 312. Initial state heat storage module; 3121. Inner spiral pipeline; 3122. Outer spiral pipeline; 3123. Fluid channel; 32. Heat storage tank; 321. First heat storage tank; 322. Second heat storage tank; 33. First injection pipeline; 331. Injection pump; 34. First output pipeline; 35. Balancing pipeline; 36. Heat exchange module; 361. Heat exchange pipeline; 362. Heat exchange pump; 37. Recovery pipeline; 371. Recovery valve; 38. Internal circulation pipeline; 381. Internal circulation valve; 39. Protective gas input pipe; 310. Heat storage medium replenishment pipe;

[0034] 4. Electric furnace;

[0035] 5. Dust removal system;

[0036] F. Axial direction of the flue gas conveying duct. Detailed Implementation

[0037] 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.

[0038] 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.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this 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.

[0040] like Figure 1 and Figure 2 As shown, the present invention provides a multi-stage heat recovery system connected between the electric furnace 4 and the dust removal system 5. The multi-stage heat recovery system includes:

[0041] The flue duct 1 is connected to the electric furnace 4 at its inlet and to the dust removal system 5 at its outlet.

[0042] Waste heat utilization unit 2 has a multi-stage heat exchange module 21 connected to each other and a steam drum 22 for containing steam. The multi-stage heat exchange module 21 is arranged at the outlet of the conveying flue 1.

[0043] The heat storage and collection unit 3 has a heat storage module 31 connected to the heat storage module 31 and a heat storage tank 32 for storing the heat storage medium. The heat storage module 31 is arranged in the conveying flue 1.

[0044] The multi-stage heat recovery system of the present invention can use the waste heat of flue gas output from the electric furnace 4 for the production of saturated steam products, and convert excess heat energy into storable heat energy through a heat storage medium, thereby making full use of the waste heat of flue gas. At the same time, considering the low saturation state of steam products caused by the fluctuation of flue gas heat energy, the heat storage and collection unit 3 of the present invention can collect excess heat when the waste heat is high and release it to the waste heat utilization unit 2 when the waste heat is low, thereby smoothing out heat fluctuations and solving the problem of low saturation state of steam products. Furthermore, the high-quality heat source collected by the heat storage and collection unit 3 can also be used for other industrial production, such as seawater desalination and solar thermal power generation.

[0045] Specifically, the conveying flue 1 can be designed with a corresponding shape to connect between the electric furnace 4 and the dust removal system 5 according to the actual application scenario. In this embodiment, the conveying flue 1 is generally in an "inverted U-shape" structure, which has a first flue section 11 located near the electric furnace 4, a third flue section 13 located near the dust removal system 5, and a second flue section 12 connecting the first flue section 11 and the third flue section 13. High-temperature flue gas is output from the electric furnace 4 and passes through the first flue section 11, the second flue section 12 and the third flue section 13 in sequence before entering the dust removal system 5. In this embodiment, the first flue section 11 and the third flue section 13 are both vertically arranged, and the second flue section 12 is horizontally arranged. The three together form an "inverted U-shape" structure. In other embodiments, there are no restrictions on the structural design of the conveying flue 1.

[0046] The multi-stage heat exchange module 21 of the waste heat utilization unit 2 is set in the third flue section 13 of the conveying flue 1. The multi-stage heat exchange module 21 is connected to the steam drum 22 through the conveying pipe 23 and the gas collecting pipe 24 respectively. The steam-water medium in the steam drum 22 is output from the steam drum 22 and circulates back into the steam drum 22 through the conveying pipe 23, the multi-stage heat exchange module 21 and the gas collecting pipe 24 in sequence. In this embodiment, the multi-stage heat exchange module 21 is generally a serpentine heat exchange tube structure. Of course, in other embodiments, the multi-stage heat exchange module 21 can also adopt a U-shaped heat exchange tube structure, which is not limited.

[0047] The heat storage module 31 of the heat storage and collection unit 3 has a high-temperature medium heat exchange module 311, which is arranged in the third flue section 13 of the conveying flue 1. In this embodiment, the high-temperature medium heat exchange module 311 is generally a serpentine heat exchange tube structure. Of course, in other embodiments, the high-temperature medium heat exchange module 311 can also adopt a U-shaped heat exchange tube structure, and there is no limitation on this. The heat storage tank 32 of the heat storage and collection unit 3 is connected to the high-temperature medium heat exchange module 311 through the first injection pipe 33 and the first output pipe 34, and the heat storage medium is used to collect the heat of the high-temperature flue gas in the conveying flue 1 into the heat storage tank 32.

[0048] In one feasible embodiment of the present invention, the heat storage tank 32 has a first heat storage tank 321, the outlet of the first heat storage tank 321 is connected to the inlet of the high temperature medium heat exchange module 311 through a first injection pipe 33; the inlet of the first heat storage tank 321 is connected to the outlet of the high temperature medium heat exchange module 311 through a first output pipe 34, and an injection pump 331 is connected to the first injection pipe 33.

[0049] In another feasible embodiment of the present invention, the heat storage tank 32 includes a first heat storage tank 321 and a second heat storage tank 322, wherein the outlet of the first heat storage tank 321 is connected to the inlet of the high-temperature medium heat exchange module 311 through a first injection pipe 33. In this embodiment, an injection pump 331 is connected to the first injection pipe 33; the inlet of the second heat storage tank 322 is connected to the outlet of the high-temperature medium heat exchange module 311 through a first output pipe 34.

[0050] Furthermore, the outlet of the second heat storage tank 322 is connected to the inlet of the first heat storage tank 321 through the balancing pipe 35 to realize the heat storage medium's thermal circulation between the second heat storage tank 322 and the first heat storage tank 321. In this embodiment, the heat storage medium is output from the outlet of the first heat storage tank 321, passes through the first injection pipe 33, the high-temperature medium heat exchange module 311, the first output pipe 34, the second heat storage tank 322, and the balancing pipe 35 in sequence, and flows back into the first heat storage tank 321, thus realizing the thermal circulation of the heat storage collection unit 3.

[0051] Furthermore, such as Figure 1As shown, in this embodiment of the invention, a heat exchange module 36 is connected between the second heat storage tank 322 and the first heat storage tank 321. The heat exchange module 36 is connected to the outlet of the second heat storage tank 322 and the inlet of the first heat storage tank 321 via heat exchange pipes 361. A heat exchange pump 362 is connected to the heat exchange pipes 361 to start and stop the heat exchange module 36. The heat exchange module 36 generally has a serpentine heat exchange tube structure. The stored thermal energy can be used for other thermal energy production through this heat exchange module 36, such as generating superheated steam and providing heat for seawater desalination systems. The specific method of using the stored thermal energy is not limited. In other embodiments, please refer to the relevant documentation. Figure 2 As shown, the multi-stage heat exchange module 21 is installed in the heat exchange pipeline 361. The multi-stage heat exchange module 21 is connected to the steam drum 22 through the conveying pipeline 23 and the gas collecting pipeline 24. After the steam-water medium is heated by the heat storage medium in the heat exchange pipeline 361, it is transported back to the steam drum 22. The heat exchange pipeline 361 provides a heat source for the unsaturated steam in the steam drum 22 for secondary heating, thereby improving the quality of the saturated steam product and solving the problems of steam product quality fluctuation or output fluctuation caused by flue gas waste heat fluctuation. At the same time, the heat source provided by the heat exchange pipeline 361 can further heat the saturated steam in the steam drum 22 to produce superheated steam, which can be directly used in the power generation system.

[0052] According to one embodiment of the present invention, such as Figure 1 and Figure 2 As shown, the multi-stage heat exchange module 21 has at least a primary heat exchange module 211 and a secondary heat exchange module 212 spaced apart along the axial direction F of the conveying flue 1. The primary heat exchange module 211 or the secondary heat exchange module 212 is connected to the steam drum 22 through the conveying pipe 23 and the gas collecting pipe 24, respectively, that is, the primary heat exchange module 211 and the secondary heat exchange module 212 are connected in parallel. Of course, in other embodiments, a tertiary heat exchange module or a quaternary heat exchange module (not shown in the figure) can also be provided, and the tertiary heat exchange module or the quaternary heat exchange module is spaced apart along the axial direction F of the conveying flue 1. In other embodiments, the number of heat exchange modules is not limited.

[0053] Furthermore, the heat exchange area of ​​the multi-stage heat exchange module 21 is the area exposed in the axial direction F perpendicular to the conveying flue 1. The heat exchange areas of the first-stage heat exchange module 211 and the second-stage heat exchange module 212 decrease sequentially along the direction towards the outlet of the conveying flue 1, maximizing the utilization of residual heat within the conveying flue 1 and controlling the temperature drop of the conveying flue, thus placing the high-temperature medium heat exchange module 311 in a more optimal heat exchange environment. In this embodiment, the first-stage heat exchange module 211 has two serpentine heat exchange tube structures connected in parallel, and the second-stage heat exchange module 212 has one serpentine heat exchange tube structure, such that the heat exchange area of ​​the first-stage heat exchange module 211 is twice the heat exchange area of ​​the second-stage heat exchange module 212. Of course, in other embodiments, the heat exchange areas of the multi-stage heat exchange module 21 can be set to other area relationships, which are not limited.

[0054] Furthermore, the heat storage module 31 has a high-temperature medium heat exchange module 311, which is disposed between the primary heat exchange module 211 and the secondary heat exchange module 212. In other feasible embodiments, the number of high-temperature medium heat exchange modules 311 can also be set to two (not shown in the figure). The two high-temperature medium heat exchange modules 311 are arranged at intervals along the axial direction F of the conveying flue 1, and the two high-temperature medium heat exchange modules 311 are arranged in series. The inlet of the high-temperature medium heat exchange module 311 is located on the high-temperature medium heat exchange module 311 closest to the outlet of the conveying flue 1, and the outlet of the high-temperature medium heat exchange module 311 is located on the high-temperature medium heat exchange module 311 furthest from the outlet of the conveying flue 1. Of course, in other embodiments, there is no specific limitation on the number of high-temperature medium heat exchange modules 311.

[0055] According to one embodiment of the present invention, such as Figure 1 and Figure 2 As shown, the heat storage module 31 also has an initial state heat storage module 312, which is arranged at the inlet of the conveying flue 1 to maximize the heat stored in the heat storage medium and reduce the temperature of the high-temperature flue gas, thereby improving the waste heat utilization rate of the high-temperature flue gas.

[0056] Specifically, the initial state heat storage module 312 is arranged in the first flue section 11 of the conveying flue 1, and the initial state heat storage module 312 is connected to the first output pipeline 34. Specifically, the inlet of the initial state heat storage module 312 is connected to the outlet of the high temperature medium heat exchange module 311 through the first output pipeline 34, and the outlet of the initial state heat storage module 312 is connected to the inlet of the second heat storage tank 322 through the first output pipeline 34. After the heat storage medium of the heat storage collection unit 3 is output from the heat storage tank 32, it flows sequentially through the high-temperature medium heat exchange module 311 and the initial state heat storage module 312 before being collected back into the heat storage tank 32. In this embodiment, the inlet of the initial state heat storage module 312 is lower than the outlet of the initial state heat storage module 312 in vertical height, and the initial state heat storage module 312 is vertically arranged. The high-temperature flue gas flows from below the initial state heat storage module 312 through the initial state heat storage module 312 and from above the initial state heat storage module 312 to the second flue section 12 of the conveying flue duct 1. In other embodiments, the inlet of the initial state heat storage module 312 may also be higher than the outlet of the initial state heat storage module 312 in vertical height, and there is no restriction on this.

[0057] According to one embodiment of the present invention, see reference. Figure 3 and Figure 4 As shown, the initial state heat storage module 312 is generally a spirally coiled pipe, and the initial state heat storage module 312 has an inner spiral pipe 3121 and an outer spiral pipe 3122 connected to each other. The outer spiral pipe 3122 is sleeved on the outside of the inner spiral pipe 3121, and a fluid channel 3123 for the flow of high-temperature flue gas is formed between the inner spiral pipe 3121 and the outer spiral pipe 3122. The side of the outer spiral pipe 3122 is fixed to the inner wall of the conveying flue duct 1. The inner spiral pipe 3121 is connected to the outer spiral pipe 3122 through a welded bracket. The inner spiral pipe 3121 and the outer spiral pipe 3122 are connected in series. The heat storage medium flows through the outer spiral pipe 3122 first and then through the inner spiral pipe 3121. Of course, in other embodiments, the heat storage medium can also flow through the inner spiral pipe 3121 first and then through the outer spiral pipe 3122.

[0058] In other embodiments, the inner spiral pipe 3121 and the outer spiral pipe 3122 can also be connected in parallel; further, the side of the outer spiral pipe 3122 can be fixedly connected to the inner wall of the conveying flue 1 by welding bracket, and a fluid channel 3123 for high-temperature flue gas flow is formed between the outer spiral pipe 3122 and the inner wall of the conveying flue 1; in other embodiments, the initial state heat storage module 312 can also be just a single spiral pipe, and there is no limitation on this.

[0059] In this embodiment, please refer to the following: Figure 1 and Figure 2As shown, the first output pipe 34 of the heat storage and collection unit 3 is connected to a recovery pipe 37, which is connected to the inlet of the first heat storage tank 321. This allows the heat storage medium heated by the high-temperature medium heat exchange module 311 to flow back into the first heat storage tank 321, thereby increasing the temperature of the heat storage medium in the first heat storage tank 321 and keeping the heat storage medium at its optimal operating temperature.

[0060] Specifically, one end of the recovery pipeline 37 is connected to the inlet of the first heat storage tank 321, and the other end of the recovery pipeline 37 is connected to the first output pipeline 34 between the inlet of the initial heat storage module 312 and the outlet of the high-temperature medium heat exchange module 311. The recovery pipeline 37 is connected to the first output pipeline 34. Furthermore, a recovery valve 371 is connected to the recovery pipeline 37, and the opening and closing of the recovery valve 371 is controlled according to the temperature of the heat storage medium in the first heat storage tank 321.

[0061] According to one embodiment of the present invention, see reference. Figure 2 As shown, an internal circulation pipe 38 is connected between the first injection pipe 33 and the first output pipe 34, so that the heat storage medium in the first heat storage tank 321 flows into the second heat storage tank 322 to reduce the temperature of the second heat storage tank 322 and prevent the heat storage medium from having a reduced lifespan due to excessive temperature.

[0062] Specifically, the flow pattern of the heat storage medium in the internal circulation pipeline 38 is regulated by the principle that the flow rate of the high-temperature heat storage medium is greater than that of the low-temperature heat storage medium. In this embodiment, one end of the internal circulation pipeline 38 is connected to the first injection pipeline 33, and the other end of the internal circulation pipeline 38 is connected to the first output pipeline 34 between the outlet of the initial state heat storage module 312 and the inlet of the second heat storage tank 322. An internal circulation valve 381 is connected to the internal circulation pipeline 38, and the opening and closing of the internal circulation valve 381 is controlled according to the temperature of the heat storage medium in the second heat storage tank 322.

[0063] Furthermore, the heat storage and collection unit 3 also has a protective gas input pipe 39 and a heat storage medium replenishment pipe 310. Both the protective gas input pipe 39 and the heat storage medium replenishment pipe 310 are connected to the balance pipe 35. The protective gas input pipe 39 is used to replenish the protective gas to protect the heat storage medium in the pipe of the heat storage and collection unit 3, and at the same time avoid the occurrence of other gases in the pipe due to the loss of protective gas, which would then lead to the loss of the heat storage medium. The heat storage medium replenishment pipe 310 is used to replenish the heat storage medium in the pipe of the heat storage and collection unit 3, and avoid the heat storage capacity of the heat storage and collection unit 3 from decreasing due to the loss of the heat storage medium.

[0064] 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 multi-stage heat recovery system, characterized in that, Connected between the electric furnace and the dust removal system, the multi-stage heat recovery system includes: The flue is connected to the electric furnace at its inlet and to the dust removal system at its outlet. The waste heat utilization unit has interconnected multi-stage heat exchange modules and a steam drum for containing steam, with the multi-stage heat exchange modules arranged at the outlet of the conveying flue. The heat storage and collection unit has a heat storage module connected to the heat storage module and a heat storage tank for storing the heat storage medium, wherein the heat storage module is arranged in the conveying flue. The heat storage module has a high-temperature medium heat exchange module, which is arranged at the outlet of the conveying flue. The heat storage tank has a first heat storage tank, which is connected to the high-temperature medium heat exchange module. The heat storage tank has a second heat storage tank connected to the first heat storage tank. The outlet of the first heat storage tank is connected to the inlet of the high-temperature medium heat exchange module through a first injection pipeline. The outlet of the high-temperature medium heat exchange module is connected to the inlet of the second heat storage tank through a first output pipeline. A recovery pipeline is connected to the first output pipeline, and the recovery pipeline is connected to the inlet of the first heat storage tank; The heat storage module also includes an initial state heat storage module, which is arranged at the inlet of the conveying flue and connected to the first output pipeline. An internal circulation pipeline is connected between the first injection pipeline and the first output pipeline; The multi-stage heat exchange module has at least a primary heat exchange module and a secondary heat exchange module spaced apart along the axial direction of the conveying flue. The primary heat exchange module and the secondary heat exchange module are respectively connected to the steam drum, and the high-temperature medium heat exchange module is located between the primary heat exchange module and the secondary heat exchange module.

2. The multi-stage heat recovery system according to claim 1, characterized in that, A heat exchange module is connected between the second heat storage tank and the first heat storage tank, and the heat exchange module is connected to the multi-stage heat exchange module through heat exchange pipelines.

3. The multi-stage heat recovery system according to claim 1, characterized in that, The heat exchange area of ​​the primary heat exchange module and the heat exchange area of ​​the secondary heat exchange module decrease sequentially along the direction toward the outlet of the conveying flue.

4. The multi-stage heat recovery system according to claim 1, characterized in that, The initial state heat storage module has an inner spiral pipe and an outer spiral pipe connected to each other, and the outer spiral pipe is sleeved on the outside of the inner spiral pipe.

5. The multi-stage heat recovery system according to claim 1, characterized in that, The heat storage and collection unit also has a protective gas input pipe, and a balance pipe is connected between the first heat storage tank and the second heat storage tank. The protective gas input pipe is connected to the balance pipe.

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