System and method for utilizing waste heat of heat storage shaft furnace by directly reducing high-temperature flue gas

Abstract

The invention discloses a heat storage shaft furnace waste heat utilization system and method for directly reducing high-temperature flue gas, and the system comprises a high-temperature flue gas pipe, a low-temperature flue gas pipe, a gravity dust collector, a combustion chamber, a hot air cooling shaft furnace, a cold air heating shaft furnace, a heat storage ball, a cooling air blower, a low-temperature air pipe and a high-temperature air pipe, each of the hot air cooling shaft furnace and the cold air heating shaft furnace comprises a furnace body, an air equalizer, a discharger and a chute, the furnace body is filled with heat storage balls, and the discharger at the lower end of the furnace body of the hot air cooling shaft furnace is connected with the chute at the upper end of the furnace body of the cold air heating shaft furnace; an unloader at the lower end of the furnace body of the cold air heating shaft furnace is connected with a chute at the upper end of the furnace body of the hot air cooling shaft furnace through a material lifting device; according to the method, a heat storage ball serves as a heat exchange medium, the heat value of high-temperature flue gas is firstly transmitted to the heat storage ball through a hot air cooling shaft furnace, then the heated heat storage ball is transmitted to normal-temperature gas through a cold air heating shaft furnace, and therefore the gas preheating function is achieved, and the waste heat utilization rate of the high-temperature flue gas is greatly increased.

Description

Technical Field

[0001] The present invention relates to high-temperature flue gas treatment technology, in particular to a regenerative shaft furnace waste heat utilization system and method for recovering and utilizing waste heat from high-temperature flue gas generated by direct reduction smelting. Background Art

[0002] China is a major industrial country. In recent years, China's annual crude steel output has exceeded 1 billion tons, accounting for more than half of the global output. At present, China's iron and steel industry mainly uses the long-process production process of blast furnaces and converters, and the production capacity of short-process steelmaking such as electric furnaces is only about 10%. The long-process iron and steel production process is complex, with high system investment and large comprehensive carbon emissions. However, due to its mature production process and low system cost control, it is still the mainstream process in current iron and steel production.

[0003] A large number of R & D and industrialization technology promotions of new ironmaking processes such as direct reduction have been carried out at home and abroad, mainly including direct reduction ironmaking processes such as rotary kiln direct reduction method, Hismelt process, Corex process, and Finex process. These direct reduction processes all use coal as fuel and reducing agent, eliminate coke, and do not require processes such as sintering and pelletizing, with the advantages of short process flow, low production investment, and small comprehensive emissions. However, the fundamental reason why the direct reduction production process cannot be widely promoted and applied is still the high comprehensive production energy consumption. The coal consumption per ton of iron production is often as high as 800 or even 1000 kg, and the system energy efficiency level urgently needs to be improved. The high-temperature flue gas generated by the direct reduction smelting production process often has an external discharge temperature as high as 1300 °C, and contains about 10% concentration of CO. The existing waste heat utilization of high-temperature flue gas still stays at recovering waste heat by using waste heat boilers, steam power generation, etc., and the system waste heat utilization efficiency is only about 20%. Therefore, it is urgent to develop a new waste heat recovery and utilization process. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a direct reduction high-temperature flue gas regenerative shaft furnace waste heat utilization system and method, which can greatly improve the waste heat utilization rate of high-temperature flue gas.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A direct reduction high-temperature flue gas regenerative shaft furnace waste heat utilization system, including a high-temperature flue gas pipe, a low-temperature flue gas pipe, a gravity dust collector, a combustion chamber, a hot air cooling shaft furnace, a cold air heating shaft furnace, regenerative balls, a cooling blower, a low-temperature air pipe, and a high-temperature air pipe; The hot air cooling shaft furnace is arranged above the cold air heating shaft furnace. Both the hot air cooling shaft furnace and the cold air heating shaft furnace include a furnace body, an air distributor, a discharger, and a chute. The furnace body is filled with heat storage balls. The chute is arranged at the upper end of the furnace body, the discharger is arranged at the lower end of the furnace body, and the air distributor is arranged in the center of the lower part of the furnace body. The discharger at the lower end of the furnace body of the hot air cooling shaft furnace is connected to the chute at the upper end of the furnace body of the cold air heating shaft furnace. The discharger at the lower end of the furnace body of the cold air heating shaft furnace is connected to the chute at the upper end of the furnace body of the hot air cooling shaft furnace through a material lifting device. The low-temperature flue gas pipe is arranged on the side of the upper part of the furnace body of the hot air cooling shaft furnace. The low-temperature flue gas pipe is successively connected to a dust collector, a induced draft fan, and a chimney. The high-temperature flue gas pipe is arranged on the side of the lower part of the furnace body of the hot air cooling shaft furnace and is connected to the air distributor. A gravity dust collector and a combustion chamber are successively arranged on the high-temperature flue gas pipe along the direction of the flue gas flow. The low-temperature air pipe is arranged on the side of the lower part of the furnace body of the cold air heating shaft furnace and is connected to the air distributor. A cooling blower is arranged on the low-temperature air pipe. The high-temperature air pipe is arranged on the side of the upper part of the furnace body of the cold air heating shaft furnace.

[0006] Furthermore, the furnace bodies of the hot air cooling shaft furnace and the cold air heating shaft furnace are both cylindrical. The air distributor includes a conical cover body, and a plurality of air outlets are uniformly arranged on the conical cover body.

[0007] Furthermore, the heat storage balls are high-temperature resistant ceramic balls based on alumina, the diameter of the ball is 10 - 60 mm, and voids are arranged inside the ball.

[0008] Furthermore, the material lifting device includes a bottom conveyor, a vibrating screen machine, a screen-bottom ash bin, a screen-bottom ash valve, a hoist, and a top conveyor. The inlet of the bottom conveyor is arranged below the discharger at the lower end of the furnace body of the cold air heating shaft furnace. The vibrating screen machine is arranged below the outlet of the bottom conveyor. The screen-bottom ash bin is arranged below the vibrating screen machine. The screen-bottom ash valve is arranged below the screen-bottom ash bin. The upper outlet of the vibrating screen machine is connected to the bottom inlet of the hoist. The top outlet of the hoist is connected to the inlet of the top conveyor. The outlet of the top conveyor is connected to the chute at the upper end of the furnace body of the hot air cooling shaft furnace.

[0009] Furthermore, the lower end of the gravity dust collector is connected to an ash storage bin, and a ash discharge valve is arranged at the lower end of the ash storage bin.

[0010] Furthermore, the combustion chamber is connected to a combustion air supply pipe, and a supplementary combustion blower is arranged on the combustion air supply pipe.

[0011] According to the above-mentioned waste heat utilization system, a method for waste heat utilization of a direct reduction high-temperature flue gas heat storage shaft furnace includes the following steps: 1) Gravity dust removal: The high-temperature flue gas generated by direct reduction smelting first enters the gravity dust collector through the high-temperature flue gas pipe for primary dust removal, and then is discharged to the outside and enters the combustion chamber. 2) Supplementary combustion: The high-temperature flue gas enters the combustion chamber for combustion, and then enters the furnace body of the hot air cooling shaft furnace through the high-temperature flue gas pipe. 3) Heating of heat storage balls in the hot air cooling shaft furnace: The high-temperature flue gas introduced into the furnace body of the hot air cooling shaft furnace is evenly distributed in the furnace body under the action of the air distributor, and then rises in the furnace body under the action of the induced draft fan and exchanges heat with the heat storage balls. The cooled flue gas is transported to the dust collector for dust removal through the low-temperature flue gas pipe at the upper part of the furnace body, and then discharged to the outside through the chimney. The heat storage balls are continuously heated, and continuously descend under the action of gravity and are discharged through the discharge device at the lower end of the furnace body; 4) Heating of normal-temperature gas by the cold air heating shaft furnace: The heat storage balls heated by the hot air cooling shaft furnace continuously descend to the inside of the cold air heating shaft furnace through the discharge device and the chute. The heat storage balls continuously descend under the action of gravity and are discharged through the discharge device at the lower end of the furnace body. Normal-temperature air is introduced into the furnace body of the hot air cooling shaft furnace through the cooling blower, and is evenly distributed in the furnace body under the action of the air distributor, and then rises in the furnace body and exchanges heat with the heat storage balls. The heat storage balls are continuously cooled, and the heated air is sent out through the high-temperature gas pipe at the upper part of the furnace body for utilization; 5) Recycling of heat storage balls: The heat storage balls cooled by the hot air cooling shaft furnace are discharged through the discharge device at the lower end of the furnace body, and then transported back to the furnace body of the hot air cooling shaft furnace by the material lifting device and are heated again by the high-temperature flue gas introduced into the hot air cooling shaft furnace.

[0012] Furthermore, the temperature of the high-temperature flue gas entering the hot air cooling shaft furnace through the high-temperature gas pipe is not lower than 800 °C, the temperature of the flue gas discharged from the hot air cooling shaft furnace to the low-temperature gas pipe does not exceed 200 °C, and the temperature of the air discharged from the cold air heating shaft furnace to the high-temperature air pipe is not lower than 600 °C.

[0013] Furthermore, the temperature of the heat storage balls discharged through the discharge device at the lower end of the furnace body of the hot air cooling shaft furnace is not lower than 600 °C, and the temperature of the heat storage balls discharged through the discharge device at the lower end of the furnace body of the cold air heating shaft furnace does not exceed 200 °C.

[0014] Furthermore, the residence time of the heat storage balls in both the hot air cooling shaft furnace and the cold air heating shaft furnace is 20 to 300 minutes, and the time taken for the heat storage balls to complete one cycle through the hot air cooling shaft furnace, the cold air heating shaft furnace, and the material lifting device is 60 to 600 minutes.

[0015] Beneficial effects: In the high-temperature flue gas regenerative shaft furnace waste heat utilization system and method of the present invention, regenerative balls are used as the heat exchange medium. The hot air cooling shaft furnace and the cold air heating shaft furnace are respectively used to cool the directly reduced high-temperature flue gas and heat the normal-temperature gas. The calorific value of the high-temperature flue gas is first transferred to the regenerative balls through the hot air cooling shaft furnace, and then the heated regenerative balls are transferred to the normal-temperature gas through the cold air heating shaft furnace, thereby realizing the gas preheating function. The system has advantages such as high waste heat recovery rate in treating high-temperature flue gas by this method. In terms of waste heat recovery, through this method of treatment, the effective utilization rate of the waste heat of the high-temperature flue gas exceeds 80%, compared with only about 20% utilization rate of the traditional process, and the waste heat recovery efficiency is increased by 4 times. In terms of the disposal of high-temperature flue gas, the sedimentation and cooling of high-temperature flue gas can be realized, and the treated high-temperature flue gas can be directly discharged through a bag filter, greatly reducing the system investment and operation cost of the traditional dust removal process.

[0016] The present invention can not only be used in the process of directly reducing iron from iron-containing materials, but also in the waste heat recovery of high-temperature flue gas in other industrial kilns, boilers, incinerators and other fields. It has the advantages of wide application fields, low system investment, reliable equipment operation, high waste heat recovery efficiency, low cost of ultra-clean flue gas emission, etc. The invention has significant technical and market advantages, and has significant energy-saving and carbon-reduction significance. The project has a huge market promotion space. Brief Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of a regenerative shaft furnace for directly reducing high-temperature flue gas waste heat utilization system.

[0018] In the figure: 1 - high-temperature flue gas pipe; 2 - low-temperature flue gas pipe; 3 - gravity dust collector; 4 - ash storage bin; 5 - ash discharge valve; 6 - combustion chamber; 7 - supplementary combustion blower; 8 - hot air cooling shaft furnace; 9 - cold air heating shaft furnace; 10 - regenerative ball; 11 - furnace body; 12 - air distributor; 13 - discharger; 14 - chute; 15 - cooling blower; 16 - bottom conveyor; 17 - vibrating screen; 18 - undersize ash bin; 19 - undersize ash valve; 20 - elevator; 21 - top conveyor; 22 - dust collector; 23 - induced draft fan; 24 - chimney; 25 - combustion air duct; 26 - low-temperature air duct; 27 - high-temperature air duct. Detailed Embodiments

[0019] The following further explains the present invention with reference to the drawings.

[0020] As Figure 1 shown, a directly reduced high-temperature flue gas regenerative shaft furnace waste heat utilization system of the present invention includes a high-temperature flue gas pipe 1, a low-temperature flue gas pipe 2, a gravity dust collector 3, a combustion chamber 6, a hot air cooling shaft furnace 8, a cold air heating shaft furnace 9, regenerative balls 10, a cooling blower 15, a low-temperature air duct 26, and a high-temperature air duct 27.

[0021] The hot air cooling vertical furnace 8 is arranged above the cold air heating vertical furnace 9. Both the hot air cooling vertical furnace 8 and the cold air heating vertical furnace 9 include a furnace body 11, an air distributor 12, a discharge device 13, and a chute 14. The furnace body 11 is filled with heat storage balls 10. The chute 14 is arranged at the upper end of the furnace body 11, the discharge device 13 is arranged at the lower end of the furnace body 11, and the air distributor 12 is arranged at the center of the lower part of the furnace body 11. The discharge device 13 at the lower end of the furnace body 11 of the hot air cooling vertical furnace 8 is connected to the chute 14 at the upper end of the furnace body of the cold air heating vertical furnace 9. The discharge device 13 at the lower end of the furnace body 11 of the cold air heating vertical furnace 9 is connected to the chute 14 at the upper end of the furnace body 11 of the hot air cooling vertical furnace 8 through a material lifting device.

[0022] The low-temperature flue gas pipe 2 is arranged on the upper side of the side of the furnace body 11 of the hot air cooling vertical furnace 8. The low-temperature flue gas pipe 2 is successively connected to a dust collector 22, an induced draft fan 23, and a chimney 24. The high-temperature flue gas pipe 1 is arranged on the lower side of the side of the furnace body 11 of the hot air cooling vertical furnace 8 and is connected to the air distributor 12. A gravity dust collector 3 and a combustion chamber 6 are successively arranged on the high-temperature flue gas pipe 1 along the flue gas traveling direction. The low-temperature air pipe 26 is arranged on the lower side of the side of the furnace body 11 of the cold air heating vertical furnace 9 and is connected to the air distributor 12. A cooling blower 15 is arranged on the low-temperature air pipe 26. The high-temperature air pipe 27 is arranged on the upper side of the side of the furnace body 11 of the cold air heating vertical furnace 9.

[0023] In this embodiment, the material lifting device includes a bottom conveyor 16, a vibrating screen machine 17, a screen undersize bin 18, a screen undersize ash valve 19, a hoist 20, and a top conveyor 21. The inlet of the bottom conveyor 16 is arranged below the discharge device 13 at the lower end of the furnace body 11 of the cold air heating vertical furnace 9. The vibrating screen machine 17 is arranged below the outlet of the bottom conveyor 16. The screen undersize bin 18 is arranged below the vibrating screen machine 17. The screen undersize ash valve 19 is arranged below the screen undersize bin 18. The upper outlet of the vibrating screen machine 17 is connected to the bottom inlet of the hoist 18. The top outlet of the hoist 18 is connected to the inlet of the top conveyor 19. The outlet of the top conveyor 19 is connected to the chute 14 at the upper end of the furnace body 11 of the hot air cooling vertical furnace 8.

[0024] Among them, the furnace bodies 11 of the hot air cooling shaft furnace 8 and the cold air heating shaft furnace 9 are both cylindrical, supported by steel structures, and refractory insulation materials are installed inside, with the thickness of the insulation materials being 50 - 300 mm. The main body of the chute 14 is made of steel structure material, and refractory insulation materials are installed inside, with the thickness of the insulation materials being 50 - 300 mm. The discharge device 13 is a high-temperature resistant discharge device that can be electrically opened. The air distributor 12 includes a conical cover supported by a steel structure. A plurality of air outlets are evenly arranged on the conical cover to facilitate the uniform supply of the introduced gas. The heat storage balls 10 are high-temperature resistant ceramic balls based on alumina, with a sphere diameter of 10 - 60 mm. Void spaces are provided inside the spheres to facilitate heat storage and heat exchange. These ceramic balls can withstand high temperatures of not less than 1600 °C. The vibrating screen machine 17 is a high-temperature resistant vibrating screen made of steel structure, and it can operate stably for a long time at high temperatures of not less than 200 °C. The ash bin 18 under the screen is a steel structure silo. The ash valve 19 under the screen is a high-temperature resistant discharge valve that can be electrically opened.

[0025] Among them, the high-temperature flue gas pipe 1, the low-temperature flue gas pipe 2, the combustion air pipe 25, the low-temperature air pipe 26, and the high-temperature air pipe 27 are all steel structure pipes. Among them, refractory insulation materials are installed inside the high-temperature flue gas pipe 1 and the high-temperature air pipe 27, and the thickness of the refractory materials is not less than 50 mm. The main bodies of the gravity dust collector 3 and the ash storage bin 4 are made of steel structure materials, and refractory insulation materials are installed inside, with the thickness of the insulation materials being 50 - 300 mm. The upper part of the gravity dust collector 3 is cylindrical, and the lower part is inverted conical. The lower end of the gravity dust collector 3 is connected to the ash storage bin 4 for storing the dust separated from the flue gas. A discharge valve 5 is provided at the lower end of the ash storage bin 4 to discharge the dust to the outside. The discharge valve 5 is a high-temperature resistant discharge valve that can be electrically opened. The combustion chamber 6 is supported by a steel structure or reinforced concrete, and the main body is built with refractory insulation materials for directly reducing the combustion of combustible gases such as CO contained in the high-temperature flue gas. The combustion chamber 6 is connected to the combustion air pipe 25 for supplying combustion-supporting air to the combustion chamber 6, and a supplementary combustion blower 7 is provided on the combustion air pipe 25. The supplementary combustion blower 7 is a variable frequency blower. The dust collector 22 is a bag filter, the induced draft fan 23 is a variable frequency blower, and the chimney 24 is a steel structure chimney. The induced draft fan 23 is a variable frequency blower.

[0026] A method for recovering waste heat from a directly reduced high-temperature flue gas regenerative shaft furnace of the above waste heat recovery system includes the following steps: 1) Gravity dust removal: The high-temperature flue gas generated by direct reduction smelting first enters the gravity dust collector 3 through the high-temperature flue gas pipe 1 for primary dust removal, and then is discharged to the outside and enters the combustion chamber 6. The dust in the flue gas is deposited in the ash storage bin 4 through the gravity dust collector 3, and then returns to the production smelting process through the discharge valve 5; 2) Supplementary combustion: The high-temperature flue gas enters the combustion chamber 6 for combustion. Combustion-supporting air is supplied to the combustion chamber 6 through the supplementary combustion blower 7, and then enters the furnace body 11 of the hot air cooling shaft furnace 8 through the high-temperature flue gas pipe 1; 3) Heating of the heat storage balls 10 in the hot air cooling shaft furnace 8: The high-temperature flue gas introduced into the furnace body 11 of the hot air cooling shaft furnace 8 is evenly distributed in the furnace body 11 under the action of the air distributor 12, and then rises in the furnace body 11 under the action of the induced draft fan 23 and exchanges heat with the heat storage balls 10. The cooled flue gas is transported to the dust collector 22 for dust removal through the low-temperature flue gas pipe 2 at the upper part of the furnace body 11, and then discharged to the outside through the chimney 24. The heat storage balls 10 are continuously heated, and continuously descend under the action of gravity and are discharged through the discharge device 13 at the lower end of the furnace body 11; 4) Heating of the normal temperature gas by the cold air heating shaft furnace 9: The heat storage balls 10 heated by the hot air cooling shaft furnace 8 continuously descend to the cold air heating shaft furnace 9 through the discharge device 13 and the chute 14. The heat storage balls 10 continuously descend under the action of gravity and are discharged through the discharge device 13 at the lower end of the furnace body 11. The normal temperature air is introduced into the furnace body 11 of the hot air cooling shaft furnace 8 through the cooling blower 15, and is evenly distributed in the furnace body 11 under the action of the air distributor 12, and then rises in the furnace body 11 and exchanges heat with the heat storage balls 10. The heat storage balls 10 are continuously cooled, and the heated air is sent out for utilization through the high-temperature gas pipe 1 at the upper part of the furnace body 11; 5) Recycling of the heat storage balls 10: The heat storage balls 10 cooled by the hot air cooling shaft furnace 8 are discharged through the discharge device 13 at the lower end of the furnace body 11, and then transported back to the furnace body 11 of the hot air cooling shaft furnace 8 by the material lifting device and are heated again by the high-temperature flue gas introduced into the hot air cooling shaft furnace 8. In this step, the dust screened by the vibrating screen 17 of the material lifting device and the broken heat storage ball 10 particles are regularly cleaned and transported out through the under-screen ash bin 18 and the under-screen ash valve 19. The heat storage balls 10 on the vibrating screen 17 enter the bottom of the elevator 20, and then are lifted by the elevator 20 to the entrance of the top conveyor 21, and then transported by the top conveyor 21 to the chute 14 at the upper end of the furnace body of the hot air cooling shaft furnace 8, and then enter the furnace body 11 of the hot air cooling shaft furnace 8. The heat storage balls 10 are recycled according to the methods in steps 3) and 4) above.

[0027] According to the above steps 1) to 5), the hot air cooling shaft furnace 8 is used to cool the high-temperature flue gas and meet the temperature conditions required by the bag filter, realizing ultra-clean emission. At the same time, the heat storage balls 10 are heated to provide a stable heat source for heating the normal temperature gas by the subsequent cold air heating shaft furnace 9, and the heated gas can be sent out for utilization. The heat storage balls 10 are recycled in the hot air cooling shaft furnace 8 and the cold air heating shaft furnace 9, realizing the waste heat utilization and ultra-clean emission of the high-temperature flue gas.

[0028] Among them, the temperature of the high-temperature flue gas entering the hot air cooling shaft furnace 8 through the high-temperature flue gas pipe 1 is not lower than 800 °C, the temperature of the flue gas discharged from the hot air cooling shaft furnace 8 to the low-temperature gas pipe 2 does not exceed 200 °C, and the temperature of the air discharged from the cold air heating shaft furnace 9 to the high-temperature air pipe 27 is not lower than 600 °C. The temperature of the heat storage balls 10 discharged from the lower discharge device 13 of the furnace body 11 of the hot air cooling shaft furnace 8 is not lower than 600 °C, and the temperature of the heat storage balls 10 discharged from the lower discharge device 13 of the furnace body 11 of the cold air heating shaft furnace 9 does not exceed 200 °C. The residence time of the heat storage balls 10 in the hot air cooling shaft furnace 8 and the cold air heating shaft furnace 9 is 20 to 300 minutes, and the time taken for the heat storage balls 10 to complete one cycle through the hot air cooling shaft furnace 8, the cold air heating shaft furnace 9, and the material lifting device is 60 to 600 minutes.

[0029] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A direct reduction high-temperature flue gas heat storage vertical furnace waste heat utilization system, characterized in that: It includes a high-temperature flue gas pipe (1), a low-temperature flue gas pipe (2), a gravity dust collector (3), a combustion chamber (6), a hot air cooling vertical furnace (8), a cold air heating vertical furnace (9), a heat storage ball (10), a cooling blower (15), a low-temperature air duct (26), and a high-temperature air duct (27); The hot air cooling vertical furnace (8) is arranged above the cold air heating vertical furnace (9). Both the hot air cooling vertical furnace (8) and the cold air heating vertical furnace (9) comprise a furnace body (11), an air equalizer (12), a discharger (13), and a chute (14). The furnace body (11) is filled with heat storage balls (10). The chute (14) is arranged at the upper end of the furnace body (11). The discharger (13) is arranged at the lower end of the furnace body (11). The air equalizer (12) is arranged at the lower center of the furnace body (11). The discharger (13) at the lower end of the furnace body (11) of the hot air cooling vertical furnace (8) is connected to the chute (14) at the upper end of the furnace body of the cold air heating vertical furnace (9). The discharger (13) at the lower end of the furnace body (11) of the cold air heating vertical furnace (9) is connected to the chute (14) at the upper end of the furnace body (11) of the hot air cooling vertical furnace (8) through a material lifting device. A low-temperature flue gas pipe (2) is arranged on the upper side of a furnace body (11) of a hot air cooling vertical furnace (8), and the low-temperature flue gas pipe (2) is connected in sequence to a dust collector (22), an induced draft fan (23), and a chimney (24); a high-temperature flue gas pipe (1) is arranged on the lower side of a furnace body (11) of a hot air cooling vertical furnace (8) and is connected to an air equalizer (12); a gravity dust collector (3) and a combustion chamber (6) are arranged in sequence on the high-temperature flue gas pipe (1) along the direction of flue gas travel; a low-temperature air pipe (26) is arranged on the lower side of a furnace body (11) of a cold air heating vertical furnace (9) and is connected to the air equalizer (12); a cooling blower (15) is arranged on the low-temperature air pipe (26); and a high-temperature air pipe (27) is arranged on the upper side of a furnace body (11) of a cold air heating vertical furnace (9).

2. A direct reduction high-temperature flue gas heat storage vertical furnace waste heat utilization system according to claim 1, characterized in that: The furnace bodies (11) of the hot air cooling vertical furnace (8) and the cold air heating vertical furnace (9) are both cylindrical, and the air equalizer (12) comprises a conical cover body on which a plurality of air outlets are evenly arranged.

3. The direct reduction high-temperature flue gas heat storage vertical furnace waste heat utilization system according to claim 1 is characterized in that: The heat storage ball (10) is an alumina-based high-temperature resistant ceramic ball, the diameter of the ball is 10-60 mm, and a gap is provided inside the ball.

4. A direct reduction high-temperature flue gas heat storage vertical furnace waste heat utilization system according to claim 1, characterized in that: The material lifting device comprises a bottom conveyor (16), a vibrating screen (17), an under-screen ash bin (18), an under-screen ash valve (19), an elevator (20), and a top conveyor (21). The inlet of the bottom conveyor (16) is arranged below the discharger (13) at the lower end of the furnace body (11) of the cold air heating vertical furnace (9), the vibrating screen (17) is arranged below the outlet of the bottom conveyor (16), the under-screen ash bin (18) is arranged below the vibrating screen (17), the under-screen ash valve (19) is arranged below the under-screen ash bin (18), the upper screen outlet of the vibrating screen (17) is connected to the bottom inlet of the elevator (18), the top outlet of the elevator (18) is connected to the inlet of the top conveyor (19), and the outlet of the top conveyor (19) is connected to the chute (14) at the upper end of the furnace body (11) of the hot air cooling vertical furnace (8).

5. A direct reduction high-temperature flue gas heat storage vertical furnace waste heat utilization system according to claim 1, characterized in that: The lower end of the gravity dust collector (3) is connected to the ash storage bin (4), and the lower end of the ash storage bin (4) is provided with an ash discharge valve (5).

6. A direct reduction high-temperature flue gas heat storage vertical furnace waste heat utilization system according to claim 1, characterized in that: The combustion chamber (6) is connected to a combustion-supporting air duct (25), and the combustion-supporting air duct (25) is provided with a supplementary combustion blower (7).

7. A method for utilizing waste heat from a direct reduction high-temperature flue gas heat storage vertical furnace according to the waste heat utilization system of claim 1, characterized in that: The steps include: 1) Gravity dust removal: The high-temperature flue gas generated by direct reduction smelting is first passed through the high-temperature flue gas pipe (1) into the gravity dust collector (3) for primary dust removal, and then discharged into the combustion chamber (6); 2) Supplementary combustion: the high-temperature flue gas is introduced into the combustion chamber (6) for combustion, and then introduced into the furnace body (11) of the hot air cooling vertical furnace (8) through the high-temperature flue gas pipe (1); 3) Heating the heat storage balls (10) in the hot air cooling vertical furnace (8): The high-temperature flue gas in the furnace body (11) of the hot air cooling vertical furnace (8) is evenly distributed in the furnace body (11) under the action of the air equalizer (12), and then moves upward in the furnace body (11) under the action of the induced draft fan (23) and exchanges heat with the heat storage balls (10). The cooled flue gas is transported to the dust collector (22) through the low-temperature flue gas pipe (2) at the upper part of the furnace body (11) for dust removal, and then discharged to the outside through the chimney (24). The heat storage balls (10) are continuously heated and continuously move downward under the action of gravity and are discharged through the discharger (13) at the lower end of the furnace body (11); 4) The cold air heating vertical furnace (9) heats the normal temperature gas: the heat storage ball (10) heated by the hot air cooling vertical furnace (8) continuously descends through the discharger (13) and the chute (14) into the cold air heating vertical furnace (9). The heat storage ball (10) continuously descends under the action of gravity and is discharged through the discharger (13) at the lower end of the furnace body (11). Normal temperature air is introduced into the furnace body (11) of the hot air cooling vertical furnace (8) through the cooling blower (15). The normal temperature air is evenly distributed in the furnace body (11) under the action of the air equalizer (12). The normal temperature air then ascends in the furnace body (11) and exchanges heat with the heat storage ball (10). The heat storage ball (10) is continuously cooled. The heated air is sent out through the high temperature air pipe (1) at the upper part of the furnace body (11) for use. 5) Recycling of the heat storage balls (10): The heat storage balls (10) cooled by the hot air cooling vertical furnace (8) are discharged through the discharger (13) at the lower end of the furnace body (11), and then transported back into the furnace body (11) of the hot air cooling vertical furnace (8) through the material lifting device, and are heated again by the high-temperature flue gas introduced into the hot air cooling vertical furnace (8).

8. A method for utilizing waste heat from a direct reduction high-temperature flue gas heat storage vertical furnace according to claim 7, characterized in that: The temperature of the high-temperature flue gas entering the hot air cooling vertical furnace (8) through the high-temperature flue gas pipe (1) is not less than 800° C., the temperature of the flue gas discharged from the hot air cooling vertical furnace (8) to the low-temperature flue gas pipe (2) is not more than 200° C., and the temperature of the air discharged from the cold air heating vertical furnace (9) to the high-temperature flue gas pipe (27) is not less than 600° C.

9. The method for utilizing waste heat from a direct reduction high-temperature flue gas heat storage vertical furnace according to claim 7, characterized in that: The temperature of the heat storage balls (10) discharged from the lower end discharger (13) of the furnace body (11) of the vertical furnace (8) cooled by hot air is not lower than 600° C., and the temperature of the heat storage balls (10) discharged from the lower end discharger (13) of the furnace body (11) of the vertical furnace (9) heated by cold air is not higher than 200° C.

10. The method for utilizing waste heat from a direct reduction high-temperature flue gas heat storage vertical furnace according to claim 7, characterized in that: The residence time of the heat storage ball (10) in the hot air cooling vertical furnace (8) and the cold air heating vertical furnace (9) is 20 to 300 minutes. The time taken for the heat storage ball (10) to complete one cycle through the hot air cooling vertical furnace (8), the cold air heating vertical furnace (9) and the material lifting device is 60 to 600 minutes.

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