Combined flue gas waste heat recovery device of hot blast stove

Abstract

The application discloses a combined flue gas waste heat recovery device of a hot blast furnace. The device comprises a heat transfer circulation pipeline and three groups of heat exchangers in series combination, the heat exchanger series combination is composed of a plurality of heat exchanger units (10) in series, the heat exchanger unit comprises a heat exchanger (11), a heat exchange bypass valve (12), a heat transfer bypass valve (13) and an isolation valve (14), two heat exchange pipe openings (16) of the heat exchanger are connected in parallel with the heat exchange bypass valve; two heat transfer pipe openings (15) of the heat exchanger are connected in parallel with the heat transfer bypass valve; four isolation valves are respectively arranged at the two pipe openings of the heat exchanger; the heat transfer pipe end (117) of the flue gas heat exchanger series combination (1), the air heat exchanger series combination (2) and the coal gas heat exchanger series combination (3) is communicated with the heat transfer circulation pipeline. In the flue gas waste heat recovery device, the heat exchanger can be disassembled and repaired conveniently and quickly, and the flue gas waste heat recovery device does not need to be stopped during the disassembly and repair.

Description

Technical Field

[0001] This invention relates to a waste heat recovery technology for hot blast stove flue gas, and more particularly to a combined waste heat recovery device for hot blast stove flue gas. Background Technology

[0002] In the blast furnace ironmaking process, the hot blast stove generates a large amount of high-temperature flue gas. To prevent the heat carried by the flue gas from being wasted, heat exchangers are typically used before the flue gas is discharged to transfer the heat of the flue gas to the air and gas entering the hot blast stove, thereby preheating the air and gas and reducing energy consumption. Specifically, current heat exchangers include flue gas heat exchangers, air heat exchangers, and gas heat exchangers. There are heat transfer medium circulation pipelines between the flue gas heat exchangers and air heat exchangers, as well as between the flue gas heat exchangers and gas heat exchangers. At the flue gas heat exchanger, the heat of the flue gas is transferred to the heat transfer medium, which flows through the circulation pipelines to the air heat exchanger and gas heat exchanger. At the air heat exchanger and gas heat exchanger, the heat of the heat transfer medium is transferred to the air and gas, thus preheating the air and gas.

[0003] However, current flue gas heat exchangers, air heat exchangers, and coal gas heat exchangers are all large, monolithic components. When repairing a particular heat exchanger, the entire unit must be disassembled. During this repair, the entire heat exchanger system becomes inoperable and must be completely shut down. Moreover, the repair time is quite lengthy, often requiring nearly four months for a major overhaul, during which time the heat exchanger system must remain unused.

[0004] Shutting down the heat exchanger will cause two problems: First, the heat from the high-temperature flue gas in the hot air furnace cannot be recovered and utilized, resulting in energy waste; second, the excessively high flue gas temperature cannot meet the requirements of the subsequent desulfurization and denitrification processes, making it more difficult to purify and discharge the flue gas.

[0005] Overall, the maintenance of current flue gas heat exchangers, air heat exchangers, and gas heat exchangers is very inconvenient, and the equipment must be completely shut down before disassembly and repair can be carried out, which greatly affects the overall operating efficiency of the heat exchanger equipment.

[0006] Chinese patent (CN202730167U) discloses an improved dual preheating device for a blast furnace hot blast stove. In this patent's technical solution, the flue gas preheater is divided into two sections, connected to an air preheater and a gas preheater respectively, thus forming two separate preheating circulation devices. When the efficiency of one flue gas preheating section decreases and requires maintenance, the preheating of the other section is not affected. However, while the other flue gas preheating section operates during maintenance, the flue gas heat exchange efficiency drops to 50%. Furthermore, maintenance of one section requires shutting off relevant pipe valves and sealing blind flanges to disconnect the maintenance system during blast furnace shutdown. Reconnecting the repaired section also requires removing blind flanges and reconnecting relevant pipes during blast furnace shutdown, a cumbersome and inconvenient process. Summary of the Invention

[0007] The purpose of this invention is to provide a combined flue gas waste heat recovery device for hot air furnaces. In this flue gas waste heat recovery device, the disassembly and maintenance of the heat exchanger is targeted, convenient and quick, and the flue gas waste heat recovery device does not need to be shut down during the disassembly and maintenance process, and the flue gas waste heat recovery device operates stably and reliably.

[0008] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0009] A combined flue gas waste heat recovery device for a hot blast stove includes a heat transfer circulation pipeline. The device further includes three sets of heat exchangers connected in series, each set comprising several heat exchanger units. Each heat exchanger unit includes a heat exchanger, a heat exchange bypass valve, a heat transfer bypass valve, and isolation valves. Two heat exchanger ports of the heat exchanger are connected in parallel with the heat exchange bypass valves, with the two ends of this parallel connection being the heat exchanger tube ends of the heat exchanger unit. Two heat transfer ports of the heat exchanger are also connected in parallel with the heat transfer bypass valves, with the two ends of this parallel connection being the heat transfer tube ends of the heat exchanger unit. Four isolation valves are provided, with two isolation valves respectively installed on the pipelines at the two heat transfer ports of the heat exchanger, and the other two isolation valves also installed on the pipelines at the two heat exchanger ports of the heat exchanger. The series-connected heat exchanger assembly consists of the several heat exchangers. The system is configured with units connected in series. The non-connected heat transfer tube ends of the two heat exchanger units at both ends of the series connection serve as the two heat transfer tube ends of the heat exchanger series combination. The three sets of heat exchanger series combinations are a flue gas heat exchanger series combination, an air heat exchanger series combination, and a coal gas heat exchanger series combination. The heat transfer tube ends of the flue gas heat exchanger series combination, the air heat exchanger series combination, and the coal gas heat exchanger series combination are all connected to the heat transfer circulation pipeline. The two heat transfer tube ends of the flue gas heat exchanger series combination are connected in series in the flue gas discharge pipeline, the two heat transfer tube ends of the air heat exchanger series combination are connected in series in the air intake pipeline, and the two heat transfer tube ends of the coal gas heat exchanger series combination are connected in series in the coal gas intake pipeline.

[0010] Furthermore, the heat transfer circulation pipeline includes two circulation mains, namely a circulation rising main and a circulation falling main; the two heat transfer tube ends of the series-connected flue gas heat exchanger are respectively connected to the circulation rising main and the circulation falling main; the two heat transfer tube ends of the series-connected air heat exchanger are respectively connected to the circulation rising main and the circulation falling main, and the connection point between the series-connected air heat exchanger and the circulation rising main and the circulation falling main is higher than the connection point between the series-connected flue gas heat exchanger and the circulation rising main and the circulation falling main; the two heat transfer tube ends of the series-connected gas heat exchanger are respectively connected to the circulation rising main and the circulation falling main, and the connection point between the series-connected gas heat exchanger and the circulation rising main and the circulation falling main is higher than the connection point between the series-connected flue gas heat exchanger and the circulation rising main and the circulation falling main.

[0011] Furthermore, the flue gas waste heat recovery device also includes a flow distribution regulating valve, which is installed on the circulating riser main pipe and located between two points on the circulating riser main pipe. One point is the connection point of the circulating riser main pipe and the gas heat exchanger connected in series, and the other point is the connection point of the circulating riser main pipe and the air heat exchanger connected in series.

[0012] Furthermore, the number of heat exchanger units included in the series combination of the flue gas heat exchanger is three, the number of heat exchanger units included in the series combination of the air heat exchanger is three, and the number of heat exchanger units included in the series combination of the coal gas heat exchanger is three.

[0013] The main innovation of this flue gas waste heat recovery device lies in its transformation of the original large, monolithic heat exchanger into a series combination of several smaller heat exchanger units. This design offers the advantage that when a heat exchanger in the series combination malfunctions, only the affected smaller heat exchanger needs to be disassembled and repaired. Compared to disassembling and repairing the entire large heat exchanger, this approach is more targeted and faster. Furthermore, during disassembly and repair, the heat exchange bypass valves and heat transfer bypass valves within the heat exchanger units remain open, ensuring uninterrupted flow of the heat transfer medium and heat exchange medium through other heat exchanger units in the series combination. The entire flue gas waste heat recovery device can continue operating, avoiding the need to shut down the heat exchanger during disassembly and repair. This results in more stable operation of the flue gas waste heat recovery device, improved overall operating efficiency, prevention of heat waste from high-temperature flue gas, and favorable conditions for subsequent desulfurization and denitrification processes.

[0014] The flue gas waste heat recovery device of the present invention has the following advantages over the prior art:

[0015] 1) A heat exchanger series combination consists of several heat exchanger units connected in series, which allows for targeted and convenient disassembly and maintenance of the heat exchanger.

[0016] 2) The heat exchanger unit is equipped with a heat exchange bypass valve and a heat transfer bypass valve connected in parallel with the heat exchanger. When disassembling and repairing the heat exchanger, the heat exchange bypass valve and the heat transfer bypass valve are opened, and the entire flue gas waste heat recovery device can continue to operate, thereby making the operation of the flue gas waste heat recovery device more stable and improving the overall operating efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the connection structure of the combined flue gas waste heat recovery device for the hot air furnace of the present invention;

[0018] Figure 2 This is a schematic diagram of the connection structure of the series combination of flue gas heat exchangers in the flue gas waste heat recovery device of the present invention.

[0019] Figure 3 This is a schematic diagram of the connection structure of the heat exchanger unit in a series combination of flue gas heat exchangers.

[0020] In the diagram: 1-Flue gas heat exchanger series combination, 2-Air heat exchanger series combination, 3-Gas heat exchanger series combination, 6-Circulation riser main pipe, 7-Circulation fallback main pipe, 9-Flow distribution regulating valve, 10-Heat exchanger unit, 11-Heat exchanger, 12-Heat exchange bypass valve, 13-Heat transfer bypass valve, 14-Isolation valve, 15-Heat transfer tube port, 16-Heat exchange tube port, 17-Heat transfer tube end of heat exchanger unit, 18-Heat transfer tube end of heat exchanger unit, 117-Heat transfer tube end of flue gas heat exchanger series combination, 118-Heat transfer tube end of flue gas heat exchanger series combination, 217-Heat transfer tube end of air heat exchanger series combination, 218-Heat transfer tube end of air heat exchanger series combination, 317-Heat transfer tube end of gas heat exchanger series combination, 318-Heat transfer tube end of gas heat exchanger series combination. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0022] See Figures 1 to 3 This embodiment provides a combined flue gas waste heat recovery device for a hot air furnace. In this embodiment, the heat exchanger is easy and quick to disassemble and maintain, and the overall operation of the flue gas waste heat recovery device is stable and reliable.

[0023] The flue gas waste heat recovery device of this embodiment includes a heat transfer circulation pipeline and three sets of heat exchangers connected in series. The three sets of heat exchangers connected in series are a flue gas heat exchanger connected in series, an air heat exchanger connected in series, and a coal gas heat exchanger connected in series.

[0024] See Figure 1The heat transfer tube ends 117 of the flue gas heat exchanger series assembly 1, the air heat exchanger series assembly 2, and the gas heat exchanger series assembly 3 are all connected to the heat transfer circulation pipeline. Specifically, the heat transfer circulation pipeline includes two circulation mains, namely a circulation rising main 6 and a circulation falling main 7; the two heat transfer tube ends 117 of the flue gas heat exchanger series assembly 1 are respectively connected to the lower ends of the circulation rising main 6 and the circulation falling main 7; the two heat transfer tube ends 217 of the air heat exchanger series assembly 2 are respectively connected to the circulation rising main 6 and the circulation falling main 7, and the two heat transfer tube ends 217 of the air heat exchanger series assembly 2 are respectively connected to the circulation rising main 6 and the circulation falling main 7. The connection point between pipe end 217 and the circulating riser pipe 6 and circulating fallr pipe 7 is higher than the connection point between the two heat transfer pipe ends 117 of the flue gas heat exchanger series assembly 1 and the circulating riser pipe 6 and circulating fallr pipe 7; the two heat transfer pipe ends 317 of the gas heat exchanger series assembly 3 are respectively connected to the circulating riser pipe 6 and circulating fallr pipe 7, and the connection point between the two heat transfer pipe ends 317 of the gas heat exchanger series assembly 3 and the circulating riser pipe 6 and circulating fallr pipe 7 is also higher than the connection point between the two heat transfer pipe ends 117 of the flue gas heat exchanger series assembly 1 and the circulating riser pipe 6 and circulating fallr pipe 7. After the above connection, a closed heat transfer medium circulation path is formed between the flue gas heat exchanger series assembly 1, the air heat exchanger series assembly 2, and the gas heat exchanger series assembly 3 (the thicker line in the figure represents the heat transfer medium circulation path).

[0025] The two heat exchanger tube ends 118 of the flue gas heat exchanger series assembly 1 are connected in series in the flue gas discharge pipe of the hot blast stove; the two heat exchanger tube ends 218 of the air heat exchanger series assembly 2 are connected in series in the air intake pipe of the hot blast stove; and the two heat exchanger tube ends 318 of the gas heat exchanger series assembly 3 are connected in series in the gas intake pipe of the hot blast stove. In this way, the flue gas, air, and gas can achieve heat transfer and exchange through the heat transfer medium circulation path.

[0026] The waste heat recovery device for flue gas in this embodiment performs the heat exchange process as follows:

[0027] In the flue gas heat exchanger series assembly 1, the heat from the flue gas is transferred to the heat exchange medium. The heated heat transfer medium flows through the circulating riser manifold 6 to the air heat exchanger series assembly 2 and the gas heat exchanger series assembly 3, respectively. In the air heat exchanger series assembly 2 and the gas heat exchanger series assembly 3, the heat from the heat transfer medium is transferred to the air and the gas, respectively. The heat transfer medium, after its temperature has decreased, returns to the flue gas heat exchanger series assembly 1 through the circulating fallback manifold 7, thus realizing one heat exchange cycle. The flue gas, after undergoing certain purification treatment, is discharged from the chimney, while the heated air and gas enter the hot blast stove for mixed combustion.

[0028] It should be noted that the circulation process of the heat transfer medium described above does not require external power. Specifically, since the connection point between the flue gas heat exchanger series assembly 1 and the circulating riser manifold 6 and circulating fall manifold 7 is lower than that of the air heat exchanger series assembly 2 and the gas heat exchanger series assembly 3, the heat transfer medium, after being heated by the flue gas in the flue gas heat exchanger series assembly 1, will naturally rise along the circulating riser manifold 6. After exchanging heat with air and gas in the air heat exchanger series assembly 2 and the gas heat exchanger series assembly 3, the cooled heat transfer medium will fall back into the flue gas heat exchanger series assembly 1 along the circulating fall manifold 7, thus achieving a circulation process without external power.

[0029] It should be noted that in the series-connected flue gas heat exchanger assembly 1, under natural conditions without external power, the flow direction of the flue gas is opposite to the flow direction of the heat transfer medium. This is because the heat transfer medium that exchanges heat with the high-temperature flue gas first will rise first along the circulating riser pipe 6, thereby driving the subsequent heat transfer medium to flow in the opposite direction to the flue gas. This process is natural. Therefore, when connecting the two heat exchanger tube ends 118 of the series-connected flue gas heat exchanger assembly 1 to the flue gas discharge pipe, it is important to ensure that the flow direction of the incoming flue gas is opposite to the designed flow direction of the heat transfer medium.

[0030] It should be noted that the flue gas waste heat recovery device of the present invention is not limited to a natural circulation setting without external power, but can also be a setting with external power circulation.

[0031] The structures of the three sets of heat exchangers connected in series are basically the same, and each set of heat exchangers connected in series consists of three heat exchanger units connected in series.

[0032] See Figure 2 and Figure 3 Specifically, taking the series combination of flue gas heat exchangers 1 as an example, the series combination of flue gas heat exchangers 1 includes three heat exchanger units 10.

[0033] The heat exchanger unit 10 includes a heat exchanger 11, a heat exchange bypass valve 12, a heat transfer bypass valve 13, and isolation valves 14. The two heat exchange ports 16 of the heat exchanger 11 are connected in parallel to the heat exchange bypass valve 12 via pipelines, with the two ends of this parallel connection being the heat exchange tube ends 18 of the heat exchanger unit 10. The two heat transfer ports 15 of the heat exchanger 11 are connected in parallel to the heat transfer bypass valve 13 via pipelines, with the two ends of this parallel connection being the heat transfer tube ends 17 of the heat exchanger unit 10. There are four isolation valves 14, each located on a pipeline at one of the four ports of the heat exchanger 11. The four ports refer to the two heat exchange ports 16 and the two heat transfer ports 15 of the heat exchanger 11.

[0034] It should be noted that the four ports of the heat exchanger 11 are connected to the pipeline in a detachable manner. The four ports refer to the two heat exchange ports 16 and the two heat transfer ports 15 of the heat exchanger 11.

[0035] It should be noted that the heat exchanger 11 described in this embodiment is a prior art heat exchanger, which has an internal heat exchange cavity. A heat transfer medium flow pipe is installed within the heat exchange cavity, and this flow pipe reciprocates within the heat exchange cavity. The heat exchanger has four ports on its exterior: two heat exchange ports 16 and two heat transfer ports 15. The heat transfer medium enters the heat exchange medium flow pipe within the heat exchanger 11 through one heat exchange port 15 and exits the heat exchanger 11 through the other heat exchange port 15. Similarly, the heat exchange medium enters the heat exchange cavity within the heat exchanger 11 through one heat exchange port 16 and exits the heat exchanger 11 through the other heat exchange port 16. Heat exchange occurs between the heat exchange medium and the heat transfer medium within the heat exchanger unit 10. In this embodiment, flue gas, air, and coal gas are the heat exchange media.

[0036] See Figure 2 and Figure 3 The flue gas heat exchanger series assembly 1 is composed of three heat exchanger units 10 connected in series. Specifically, the heat transfer tube ends 17 of the three heat exchanger units 10 are connected in series, and the heat transfer tube ends 18 of the three heat exchanger units 10 are also connected in series.

[0037] See Figure 2 It should be noted that among the three heat exchanger units 10 connected in series, each heat exchanger unit 10 at both ends of the series connection has one heat transfer tube end 17 and one heat exchange tube end 18 that are not connected in series. These heat transfer tube ends 17 and 18 that are not connected in series are referred to as the non-connected heat transfer tube ends and heat exchange tube ends. The non-connected heat transfer tube ends of the two heat exchanger units 10 at both ends of the series connection serve as the two heat transfer tube ends 117 of the flue gas heat exchanger series assembly 1. The non-connected heat exchange tube ends of the two heat exchanger units 10 at both ends of the series connection serve as the two heat exchange tube ends 118 of the flue gas heat exchanger series assembly 1.

[0038] The structure of the air heat exchanger series combination 2 and the gas heat exchanger series combination 3 is basically the same as that of the flue gas heat exchanger series combination 1. The only difference is the specifications of the heat exchangers. The specifications of the heat exchangers in the air heat exchanger series combination 2 and the gas heat exchanger series combination 3 are slightly smaller than those of the heat exchangers in the flue gas heat exchanger series combination 1.

[0039] See Figure 1 and Figure 3When the flue gas waste heat recovery device of this embodiment is in normal operation, the heat exchange bypass valve 12 and the heat transfer bypass valve 13 are closed in all heat exchanger units 10, while the four isolation valves 14 are open. When a heat exchanger 11 in a heat exchanger unit 10 malfunctions and needs to be disassembled for maintenance, the heat exchange bypass valve 12 and the heat transfer bypass valve 13 are opened first, then the four isolation valves 14 are closed, and then the heat exchanger 11 can be disassembled for maintenance. When heat exchanger 11 of one heat exchanger unit 10 in the heat exchanger series assembly is disassembled, since the heat exchange bypass valve 12 and the heat transfer bypass valve 13 are in the open state, both the heat transfer medium and the heat exchange medium (flue gas, air, or coal gas) can still pass through the heat exchanger unit 10. Therefore, it does not affect the flow of the heat transfer medium and the heat exchange medium through other heat exchanger units 10 in the heat exchanger series assembly. The heat transfer medium and the heat exchange medium can still exchange heat in other heat exchanger units 10, and the entire flue gas waste heat recovery device can still continue to operate. After the heat exchanger 11 is repaired, it is reinstalled into the heat exchanger unit 10. First, the four isolation valves 14 are opened, and then the heat exchange bypass valve 12 and the heat transfer bypass valve 13 are closed.

[0040] Furthermore, since the heat exchangers 11 in this embodiment are all miniaturized, several heat exchangers can be prepared in advance as spares. When the heat exchanger that needs maintenance is removed, the spare heat exchanger can be directly arranged to replace the removed heat exchanger for installation, which can further reduce the adverse effects caused by disassembling and maintaining the heat exchanger.

[0041] The main innovation of the flue gas waste heat recovery device in this embodiment compared to the prior art lies in breaking down the original large-scale heat exchanger into smaller units, replacing it with a series combination of three heat exchanger units connected in series. The advantage of this design is that when one heat exchanger in the series combination malfunctions, only the malfunctioning small heat exchanger needs to be disassembled and repaired. Compared to disassembling and repairing the entire large heat exchanger, this method is more targeted and the disassembly and repair process is quick and convenient. Furthermore, the disassembly of the heat exchanger... During maintenance, since the heat exchange bypass valve and heat transfer bypass valve in the heat exchanger unit are in the open state, it does not affect the flow of the heat transfer medium and heat exchange medium through other heat exchanger units 10 in the series combination of heat exchangers. The entire flue gas waste heat recovery device can continue to operate, avoiding the situation where the heat exchanger equipment must be shut down when the entire heat exchanger is disassembled and maintained. This makes the operation of the flue gas waste heat recovery device more stable, improves the overall operating efficiency, avoids the waste of heat from high-temperature flue gas, and creates favorable conditions for subsequent desulfurization and denitrification processes.

[0042] Preferably, the flue gas waste heat recovery device of this embodiment further includes a flow distribution regulating valve 9. The flow distribution regulating valve 9 is installed on the circulating riser main pipe 6 and located between two points on the circulating riser main pipe 6. One point is the connection point between the circulating riser main pipe 6 and a heat transfer tube end 317 of the gas heat exchanger series assembly 3, and the other point is the connection point between the circulating riser main pipe 6 and a heat transfer tube end 217 of the air heat exchanger series assembly 2. By adjusting the flow distribution regulating valve 9, the flow ratio of the heat transfer medium flowing through the air heat exchanger series assembly 2 and the gas heat exchanger series assembly 3 can be adjusted. Especially when disassembling and repairing heat exchanger 11 in air heat exchanger series combination 2 or gas heat exchanger series combination 3, the heat exchange capacity of air heat exchanger series combination 2 and gas heat exchanger series combination 3 will differ when one heat exchanger 11 is removed. This will result in inconsistent temperatures of the heat transfer medium entering the circulating return manifold 7 from air heat exchanger series combination 2 and gas heat exchanger series combination 3. In such cases, the flow rate of the heat transfer medium flowing through air heat exchanger series combination 2 and gas heat exchanger series combination 3 can be adjusted by regulating the flow distribution regulating valve 9, thereby balancing the temperature of the heat transfer medium entering the circulating return manifold 7 from air heat exchanger series combination 2 and gas heat exchanger series combination 3.

[0043] It should be noted that in other embodiments, the number of heat exchanger units connected in series in each heat exchanger series combination is not limited to three, and several heat exchanger units can be connected in series according to actual needs.

[0044] It should be noted that the parallel, series, and pipe-end connections mentioned in this article all refer to connections made through pipes.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, 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 combined flue gas waste heat recovery device for a hot blast stove, comprising a heat transfer circulation pipeline, characterized in that: The flue gas waste heat recovery device also includes three sets of heat exchangers connected in series, and each set of heat exchangers connected in series includes several heat exchanger units. The heat exchanger unit includes a heat exchanger, a heat exchange bypass valve, a heat transfer bypass valve, and isolation valves. The two heat exchanger ports of the heat exchanger are connected in parallel with the heat exchange bypass valves, and the two ends of this parallel connection are the heat exchanger tube ends of the heat exchanger unit. The two heat transfer ports of the heat exchanger are connected in parallel with the heat transfer bypass valves, and the two ends of this parallel connection are the heat transfer tube ends of the heat exchanger unit. There are four isolation valves, of which two isolation valves are respectively installed on the pipelines at the two heat transfer ports of the heat exchanger, and the other two isolation valves are respectively installed on the pipelines at the two heat exchanger ports of the heat exchanger. The heat exchanger series combination is composed of the plurality of heat exchanger units connected in series. The non-connected heat transfer tube ends of the two heat exchanger units at both ends of the series connection serve as the two heat transfer tube ends of the heat exchanger series combination. The three sets of heat exchangers connected in series are a flue gas heat exchanger series combination, an air heat exchanger series combination, and a coal gas heat exchanger series combination; the heat transfer tube ends of the flue gas heat exchanger series combination, the air heat exchanger series combination, and the coal gas heat exchanger series combination are all connected to the heat transfer circulation pipeline; the two heat exchange tube ends of the flue gas heat exchanger series combination are connected in series in the flue gas discharge pipeline, the two heat exchange tube ends of the air heat exchanger series combination are connected in series in the air intake pipeline, and the two heat exchange tube ends of the coal gas heat exchanger series combination are connected in series in the coal gas intake pipeline.

2. The combined flue gas waste heat recovery device for the hot blast stove according to claim 1, characterized in that: The heat transfer circulation pipeline includes two circulation mains, namely a circulation rising main and a circulation falling main; The two heat transfer tubes of the series-connected flue gas heat exchanger are respectively connected to the circulating rising main pipe and the circulating falling main pipe; the two heat transfer tubes of the series-connected air heat exchanger are respectively connected to the circulating rising main pipe and the circulating falling main pipe, and the connection point between the series-connected air heat exchanger and the circulating rising main pipe and the circulating falling main pipe is higher than the connection point between the series-connected flue gas heat exchanger and the circulating rising main pipe and the circulating falling main pipe; the two heat transfer tubes of the series-connected gas heat exchanger are respectively connected to the circulating rising main pipe and the circulating falling main pipe, and the connection point between the series-connected gas heat exchanger and the circulating rising main pipe and the circulating falling main pipe is higher than the connection point between the series-connected flue gas heat exchanger and the circulating rising main pipe and the circulating falling main pipe.

3. The combined flue gas waste heat recovery device for the hot blast stove according to claim 2, characterized in that: The flue gas waste heat recovery device also includes a flow distribution regulating valve, which is installed on the circulating riser main pipe and located between two points on the circulating riser main pipe. One point is the connection point of the circulating riser main pipe and the gas heat exchanger connected in series, and the other point is the connection point of the circulating riser main pipe and the air heat exchanger connected in series.

4. The combined flue gas waste heat recovery device for the hot blast stove according to claim 1, characterized in that: The series combination of the flue gas heat exchanger includes three heat exchanger units, the series combination of the air heat exchanger includes three heat exchanger units, and the series combination of the coal gas heat exchanger includes three heat exchanger units.

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