CN207351230U - A kind of flue gas tandem recycles ring cold machine - Google Patents

Abstract

The utility model discloses an annular cooler for flue gas cascade recycling, which comprises: a first annular cold cover arranged on the high temperature area of the annular cooler, and a connection between the first annular cold cover and a high-temperature flue gas heat recovery device The first heat-absorbing air duct is connected to the high-temperature flue gas heat recovery device and the cooling air duct in the high-temperature zone of the annular cooler and/or the first heat-returning air duct of the cooling fan in the high-temperature area of the annular cooler; it is arranged in the middle temperature area of the annular cooler The second annular cold hood on the upper part is connected with the second heat-absorbing air pipe of the medium-temperature flue gas heat recovery device, and connected with the heat supply of the medium-temperature flue gas heat recovery device and the flue gas circulation system of the sintering machine. Air pipe: an exhaust tube arranged on the low temperature zone of the annular cooler, and the exhaust tube is connected to the cooling fan in the middle temperature zone of the annular cooler and/or the cooling fan in the low temperature zone of the annular cooler. The annular cooler can not only effectively increase the temperature of the flue gas discharged from the annular cooler and improve the efficiency of flue gas reuse, but also can further reduce the amount of exhaust gas discharged externally to achieve the purpose of protecting the environment.

Description

A flue gas cascade recycling circular cooler

technical field

The utility model relates to the field of iron and steel smelting, in particular to an annular cooler for flue gas cascade recycling.

Background technique

In iron and steel smelting, ring coolers are used to cool sintered materials. The ring cooler is in the shape of a ring as a whole, and the sintered material runs in the ring cooler for a week through a trolley to complete cooling and unloading. When working, the sintered materials are arranged on the grate plate of the trolley, and the trolley rotates at a constant speed around the center of the ring cooler. At the same time, the cold (or hot) air blown by the blower passes through the grate plate from bottom to top and enters the trolley. After sufficient heat exchange with the materials on the grate plate, it is discharged from the exhaust pipe as hot smoke.

The interior of the ring cooler can be divided into high temperature zone, medium temperature zone, low temperature zone and non-cooling zone. The sintered material of the sintering machine is transported to the trolley of the ring cooler in the high temperature zone. At this time, the temperature of the material is between 700°C and 800°C Between ℃, the cooling air at room temperature fully exchanges heat with the material in the high temperature zone, and becomes flue gas with a certain temperature, which is discharged from the exhaust pipe.

The temperature of the flue gas discharged from the trolley in the high temperature zone is between 350 and 500°C; when it runs to the medium temperature zone, the temperature of the material decreases after cooling in the high temperature zone, and the temperature of the flue gas discharged in the medium temperature zone is between 200°C and 350°C After passing through the medium temperature zone, the trolley runs to the low temperature zone, at this time the temperature of the material is further lower, and the temperature of the flue gas discharged in the low temperature zone is generally lower than 200°C. After passing through the low-temperature zone, the temperature of the material drops below 150°C, and is sent to the next process in the non-cooling zone to complete the cooling of the material.

During the material cooling process, a large amount of hot flue gas will be directly discharged into the atmosphere, which not only causes air pollution, but also causes waste of energy. For the sake of environmental protection and energy saving, some iron and steel enterprises recycle the hot flue gas in the high-temperature area, and use the heat energy of the high-temperature flue gas to generate electricity and steam. The utilization rate of high-temperature flue gas heat energy is closely related to the temperature of the flue gas. The higher the flue gas temperature, the higher the efficiency of heat utilization. Therefore, how to increase the temperature of the flue gas discharged from the ring cooler has a great influence on the reuse of flue gas. important meaning.

The applicant has proposed a method and system for reusing flue gas of an annular cooler, and an annular cooler, which includes an annular cooling hood arranged on the middle temperature zone of the annular cooler for collecting flue gas, and is respectively connected to the annular cooling hood and the annular cooling The rear air duct and the front air duct of the cooling air duct in the high temperature area of the machine, and a circulating fan is installed between the rear air duct and the front air duct. Cooling air in the high temperature area of the machine. In this way, the temperature of the high-temperature flue gas discharged after the heat exchange between the medium-temperature flue gas itself with a certain temperature and the high-temperature material is much higher than the temperature of the hot flue gas discharged after the high-temperature zone of the original ring refrigerator directly uses cold air to cool the material, and then This part of the high-temperature flue gas is collected for reuse in power generation, boiling water, etc., effectively improving the efficiency of heat utilization.

However, this annular cooler flue gas reuse method and system, and the annular cooler only use the flue gas in the high temperature zone of the annular cooler, and the flue gas in the middle temperature zone and low temperature zone of the annular cooler will still be discharged into the atmosphere. The machine still has the problems of causing air pollution and waste of heat energy.

Utility model content

The purpose of the utility model is to provide a flue gas cascade recycling circular cooler. The annular cooler can not only effectively increase the temperature of the flue gas discharged from the annular cooler and improve the efficiency of flue gas reuse, but also can further reduce the amount of exhaust gas discharged externally to achieve the purpose of protecting the environment.

In order to achieve the above purpose, the utility model provides a flue gas cascade recycling circular cooler, including:

The first annular cooling hood arranged on the high-temperature area of the annular cooler for collecting flue gas is connected to the first heat-absorbing air duct of the high-temperature flue gas heat recovery device, and is connected to the high-temperature flue gas heat The recovery device and the cooling air duct in the high temperature area of the annular cooler and/or the first return air duct of the cooling fan in the high temperature area of the annular cooler;

The second annular cooling hood arranged on the middle temperature zone of the annular cooler for collecting flue gas is connected to the second annular cooling hood and the second heat-absorbing air duct of the medium-temperature flue gas heat recovery device, and is connected to the heat of the medium-temperature flue gas. The heat supply air pipe of the recovery device and the flue gas circulation system of the sintering machine;

An exhaust tube arranged on the low temperature zone of the annular cooler for collecting and transporting flue gas, the exhaust tube is connected to the cooling fan in the middle temperature zone of the annular cooler and/or the cooling fan in the low temperature zone of the annular cooler.

Preferably, it also includes a third heat-absorbing air duct connecting the first cooling enclosure and/or the second cooling enclosure with the ignition furnace of the sintering machine.

Preferably, the high-temperature flue gas heat recovery device is a waste heat boiler capable of recovering heat energy of high-temperature flue gas to generate steam.

Preferably, the medium-temperature flue gas heat recovery device is a low-temperature waste heat power generation system capable of recovering heat energy of medium-temperature flue gas to generate electricity.

Preferably, the flue gas circulation system of the sintering machine includes a flue gas hood arranged on the surface of the sintering machine trolley, a flue gas circulation duct communicated with the flue gas hood, and a flue gas circulation duct arranged in the flue gas circulation duct. A gas circulation fan, the hot air pipe is connected to the flue gas circulation fan.

Preferably, it also includes a fourth heat-absorbing air duct arranged at the receiving and discharging dust removal points of the annular cooler for delivering the flue gas to the dust removal system at the tail of the machine.

Preferably, the tail dust removal system is provided with a bag filter.

Preferably, the annular cooler is provided with at least three first annular cooling hoods for collecting flue gas in the high temperature area, the radial end surface of the first annular cooling hood is in the shape of a door, and the circumferential length is the same as that of the annular cooling The length of the high-temperature zone of the machine is equivalent, and the first annular cooling cover is covered in the high-temperature area of the annular cooler, higher than the position of the trolley, and its top end is provided with a smoke exhaust port connected to a high-temperature flue gas heat recovery device.

Preferably, the annular cooler is provided with at least two second annular cooling hoods for collecting flue gas in the medium temperature zone, the radial end surface of the second annular cooling hood is in the shape of a door, and the circumferential length The length of the middle temperature zone of the machine is equivalent, and the second annular cooling cover is covered in the middle temperature area of the ring cooler, which is higher than the position of the trolley, and the top end surface is provided with a smoke exhaust port connected to a medium temperature flue gas heat recovery device.

Preferably, the exhaust tube is a circular hollow tube structure, and the circumferential length of the covered area is equivalent to the length of the low temperature zone of the annular cooler.

Preferably, a three-way pipe is provided between the exhaust cylinder and the cooling fan in the middle temperature zone of the annular cooler and/or the cooling fan in the low temperature zone of the annular cooler, and the first passage of the three-way pipe communicates with the exhaust cylinder, so The second passage of the three-way pipe fitting is the normal temperature air inlet, and the third passage of the three-way pipe fitting is connected to the cooling fan in the middle temperature zone of the ring cooler and/or the cooling fan in the low temperature zone of the ring cooler,

Preferably, a thermal expansion and contraction compensator and a first electric valve are provided on the first passage of the three-way pipe fitting, and a second electric valve is provided on the second passage of the three-way pipe fitting.

The annular cooler provided by the utility model is provided with the first annular cooling cover corresponding to the high temperature zone, the second annular cooling cover corresponding to the medium temperature zone and the exhaust tube corresponding to the low temperature zone, wherein the first annular cooling cover The collected high-temperature flue gas can be sent to the high-temperature flue gas heat recovery device through the first heat-absorbing air pipe, and after the heat is partially recovered, the flue gas with reduced temperature can return to the cooling air duct in the high-temperature area through the first heat-returning air pipe and/or Or the cooling fan in the high-temperature area, which cools the material after mixing with normal-temperature air to realize recycling; the medium-temperature flue gas collected by the second ring cooling hood can be transported to the medium-temperature flue gas heat recovery device through the second heat-absorbing air pipe, and its heat After being partially recovered, the temperature-reduced flue gas is transported to the flue gas circulation system of the sintering machine through the hot air pipe, and recycled in the sintering machine; the low-temperature flue gas collected by the exhaust pipe is transported to the middle temperature zone of the ring cooler for cooling The fan and/or the cooling fan in the low-temperature zone of the ring cooler makes the low-temperature flue gas cascade recycled, so that the exhaust gas is not discharged outside. In this way, all the flue gas discharged from the high, medium and low temperature areas of the annular cooler can be collected, and these flue gases can be used for different purposes and entered into their respective systems one by one, which can not only effectively increase the temperature of the flue gas discharged by the annular cooler, The efficiency of flue gas reuse can further reduce the amount of exhaust gas discharged to the outside, and achieve the purpose of protecting the environment.

Description of drawings

Fig. 1 is a radial sectional view of a low-temperature zone of an annular cooler disclosed in an embodiment of the present invention;

Fig. 2 is the overall plan view of the annular cooler shown in Fig. 1;

Fig. 3 is a flow chart of hot exhaust gas utilization of the annular cooler shown in Fig. 1 .

In the picture:

1. Trolley 2. Grate plate 3. Cooling fan 4. First ring cold cover 5. High temperature flue gas heat recovery device 6. First heat absorbing air duct 7. First heat return air duct 8. Second ring cold cover 9. Medium-temperature flue gas heat recovery device 10. Second heat-absorbing air pipe 11. Heat-supplying air pipe 12. Exhaust tube 13. Fourth heat-absorbing air pipe 14. Muffler 15. Thermal expansion and cold contraction compensator 16. Special-shaped Tee Fittings

A. High-temperature flue gas intake B. Medium-temperature flue gas intake C. Low-temperature flue gas intake D. Return heat pipe interface center

Detailed ways

In order to enable those skilled in the art to better understand the solution of the utility model, the utility model will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

In this article, terms such as "upper, lower, inner, outer" are established based on the positional relationship shown in the drawings, and the corresponding positional relationship may also change accordingly depending on the drawings. It is understood as an absolute limitation on the scope of protection; moreover, relative terms such as "first" and "second" are only used to distinguish one from another component with the same name, and do not necessarily require or No such actual relationship or order between these components is implied.

The annular cooler provided in this embodiment is in the form of a ring as a whole, and the sintered material is run in the annular cooler by a trolley for one week to complete cooling and unloading.

Please refer to Figure 1, which is a radial section view of the annular cooler (pointing to the center of the annular cooler). The sintered materials are arranged on the grate plate 2 of the trolley 1, and the trolley 1 rotates at a constant speed around the center of the annular cooler. At the same time, the cooling The cold (or hot) air blown by the fan 3 passes through the grate plate 2 from bottom to top and enters the trolley 1, and after sufficient heat exchange with the material on the grate plate 2, it is discharged from the exhaust pipe as hot smoke.

Please refer to Figure 2, which is the overall plan view of the ring cooler. The ring cooler is divided into high temperature zone, medium temperature zone, low temperature zone and non-cooling zone. The sintered material of the sintering machine (not shown in the figure) is in the high temperature zone It is transported to the trolley 1 of the annular cooler. At this time, the temperature of the material is between 700°C and 800°C. After the cooling air at normal temperature fully exchanges heat with the material in this high temperature area, it becomes flue gas with a certain temperature. The exhaust pipe comes out.

The temperature of the flue gas discharged from trolley 1 in the high temperature zone is between 350 and 500°C; when it runs to the medium temperature zone, the temperature of the material decreases after cooling in the high temperature zone, and the temperature of the flue gas discharged in the medium temperature zone is between 200°C and 350°C After passing through the medium temperature zone, trolley 2 runs to the low temperature zone, at this time the temperature of the material is further lower, and the temperature of the exhaust gas in the low temperature zone is generally lower than 200°C. After passing through the low-temperature zone, the temperature of the material drops below 150°C, and is sent to the next process in the non-cooling zone to complete the cooling of the material.

The annular cooler is provided with a first annular cooling cover 4 above the high temperature area for collecting high-temperature flue gas, and at the same time is provided with a first heat-absorbing air duct 6 connecting the first annular cooling cover 4 with the high-temperature flue gas heat recovery device 5 , and is provided with a first return air duct 7 that communicates the high-temperature flue gas heat recovery device 5 with the cooling air duct in the high temperature zone of the annular cooler and/or the cooling fan in the high temperature area of the annular cooler. The high-temperature flue gas collected by the first annular cooling hood 4 can be transported to the high-temperature flue gas heat recovery device 5 through the first heat-absorbing air pipe 6, and after the heat is partially recovered, the flue gas with reduced temperature can pass through the first return hot air The pipe 7 returns to the cooling air duct in the high temperature zone and/or the cooling fan in the high temperature zone, and mixes with the air at normal temperature to cool the material to realize recycling.

The temperature of the high-temperature flue gas discharged after the heat exchange between the return flue gas and the high-temperature material at a certain temperature is much higher than the temperature of the hot flue gas discharged after the high-temperature area of the original ring cooler directly uses the cold air to cool the material, and then collects the Part of the high-temperature flue gas is reused for power generation and steam production, which can effectively improve the efficiency of flue gas reuse.

The high-temperature flue gas heat recovery device 5 may be a device capable of recovering heat energy of high-temperature flue gas to generate steam, such as a direct-coupled hood type waste heat boiler and the like.

The annular cooler is provided with a second annular cooling hood 8 above the medium temperature zone to collect the medium temperature flue gas, and is also provided with a second heat absorbing air duct 10 connecting the second annular cooling hood 8 with the medium temperature flue gas heat recovery device 9 , and is provided with a heat supply air duct 11 that connects the medium-temperature flue gas heat recovery device 9 with the flue gas circulation system of the sintering machine. The medium-temperature flue gas collected by the second annular cooling hood 8 can be transported to the medium-temperature flue gas heat recovery device 9 through the second heat-absorbing air pipe 10 , and after the heat is partially recovered, the flue gas with reduced temperature is transported through the heat-supplying air pipe 11 To the flue gas circulation system of the sintering machine, it is recycled in the sintering machine.

The flue gas circulation system of the sintering machine includes a flue gas hood arranged on the surface of the sintering machine trolley, a flue gas circulation duct connected to the flue gas To the flue gas circulation fan.

The medium-temperature flue gas heat recovery device 9 may be a device capable of recovering the heat energy of the medium-temperature flue gas for power generation, such as a low-temperature waste heat power generation system.

The annular cooler is provided with an exhaust tube 12 above the low temperature zone for collecting and transporting flue gas, and the exhaust tube 12 is connected to the cooling fan in the middle temperature zone of the annular cooler and/or the cooling fan in the low temperature zone of the annular cooler. The low-temperature flue gas collected by the exhaust pipe 12 is transported to the cooling fan in the middle temperature zone of the annular cooler and/or the cooling fan in the low temperature zone of the annular cooler, so that the low-temperature flue gas can be recycled in cascade, so that the exhaust gas will not be discharged outside.

In addition, the annular cooler is also provided with a third heat-absorbing air duct (not shown in the figure) that communicates with the first annular cooling cover and/or the second annular cooling cover and the ignition furnace of the sintering machine, and is arranged on the annular cooling machine, The discharge and dust removal point is used to convey the flue gas to the fourth heat-absorbing air duct 13 of the tail dust removal system, and the tail dust removal system is equipped with a bag filter.

Specifically, the annular cooler is provided with at least three first annular cooling hoods 4 for collecting flue gas in the high-temperature area. The radial end surface of the first annular cooling hood 4 is a door-shaped, and the circumferential length is the same as the high temperature of the annular cooler. The length of the zone is equivalent, the first annular cooling cover 4 is covered in the high temperature area of the annular cooler, higher than the position of the trolley 4, and its top end surface is provided with a smoke exhaust port connected to the high-temperature flue gas heat recovery device 5, and the annular cooling cover is used to Collecting the flue gas can avoid the temperature drop after the flue gas contacts with the air and ensure the temperature of the flue gas.

After the flue gas is utilized by the direct-connected hood type waste heat boiler, part of the hot air at about 150°C returns to the annular main air duct.

The ring cooler is provided with at least two second ring cooling hoods 8 for collecting flue gas in the middle temperature zone. The radial end surface of the second ring cooling cover 8 is a door shape, and the circumferential length is the same as the length of the middle temperature zone of the ring cooler. Correspondingly, the second annular cooling cover 8 is covered in the medium temperature area of the annular cooler, higher than the position of the trolley 1, and its top end surface is provided with a smoke exhaust port connected to the medium temperature flue gas heat recovery device 9, and the flue gas is collected by the annular cooling cover , which can avoid the temperature drop after the flue gas contacts with the air, and ensure the flue gas temperature.

After the flue gas is used for power generation by low-temperature waste heat ORC, the flue gas enters the flue gas circulation system of the sintering machine for recycling.

The exhaust tube 12 is a circular hollow tube structure, and the circumferential length of the covered area is equivalent to the length of the low temperature zone of the annular cooler.

A special-shaped three-way pipe fitting 16 is arranged between the exhaust cylinder 12 and the cooling fan in the middle temperature zone of the annular cooler and/or the cooling fan in the low-temperature zone of the annular cooler. The first passage of the special-shaped three-way pipe fitting 16 is connected to the exhaust cylinder 12. The second passage of the pipe fitting 16 is the air inlet at normal temperature, and the third passage of the special-shaped three-way pipe fitting 16 is connected to the cooling fan in the middle temperature zone of the ring cooler and/or the cooling fan 3 in the low temperature zone of the ring cooler, and the hot flue gas is introduced into the inlet of the cooling fan 3, The outlet of the cooling fan 3 blows into the annular main flue, and this part of the flue gas is not discharged to the outside.

Since the cooling fan 3 is provided with a normal temperature air inlet, the first passage of the special-shaped three-way pipe fitting 16 is provided with a first electric valve, and the second passage of the special-shaped three-way pipe fitting 16 is provided with a second electric valve. and the second electric valve can respectively adjust the ratio and flow of low-temperature flue gas and normal-temperature air, thereby controlling the temperature of the mixed airflow. In addition, the valve at its horizontal section is used to balance the pressure of the two branch pipes entering the cooling fan.

In order to eliminate noise, a muffler 14 can be installed at the inlet of the air at normal temperature, and a thermal expansion and contraction compensator 15 is provided on the first passage of the special-shaped three-way pipe fitting 16. The pipe fittings are deformed by the heating of the flue gas and affect other connected components.

Please refer to FIG. 3 . FIG. 3 is a flowchart of the utilization of hot exhaust gas of the annular cooler shown in FIG. 1 .

As shown in the figure, the annular cooler is provided with six cooling fans under the grate plate 2, which are No. 1 fan, No. 2 fan, No. 3 fan, No. 4 fan, No. 5 fan and No. 6 fan. These fans are A circulating fan that can suck in cold/hot air and blow it into the cooling air duct.

The utilization of ring cold and hot waste gas consists of four parts: steam production by waste heat boiler, ignition and combustion support, low-temperature waste heat ORC power generation, and cascade utilization.

In the first part, the heat of the hot waste gas in the high temperature section of the ring cooler is recovered by the direct-coupled hood type waste heat boiler technology to generate steam, and the heat of the flue gas is recovered and returned to the flue of the ring cooler or the second fan of the ring cooler for reuse.

In the second part, part of the high-temperature flue gas at about 350°C in the high-temperature section of the annular cooler can be directed to the ignition furnace of the sintering machine for ignition and combustion support or hot air heat preservation.

In the third part, the heat of the hot waste gas in the low-temperature section of the ring cooler adopts low-temperature waste heat ORC power generation technology to recover heat energy, and the waste gas after waste heat recovery enters the flue gas circulation sintering system, and is sent to the sintering machine after being combined with the flue gas of the sintering circulation flue by the fan Inside the fume hood on the trolley surface.

The fourth part is the exhaust gas in the low-temperature section of the annular cooler. The exhaust gas is used as cooling air for secondary use through the cascade utilization technology of the annular cooler fans.

In addition, the exhaust gas from the receiving and unloading dust removal points of the ring cooler enters the dust removal system at the tail of the machine, and a bag filter is installed to deal with the remaining flue gas, so that the ring cooling exhaust gas will not be discharged outside.

The utility model collects the flue gas discharged from the high temperature area of the ring cooler, and part of the flue gas with a certain temperature is used as the cooling air in the corresponding temperature area of the ring cooler. , to become hot flue gas with a higher temperature, and then collect this part of the high-temperature flue gas for power generation, steam production, etc., to effectively improve the efficiency of flue gas reuse.

At the same time, the utility model also collects the flue gas discharged from the low-temperature area of the last section of the exhaust pipe of the annular cooler, and enters the front No. 4 and No. 5 cooling fans through the bypass system, so that the low-temperature flue gas can be recycled in cascade, thereby realizing the waste gas No external discharge can further reduce the amount of exhaust gas discharged externally and achieve the purpose of protecting the environment.

The above-mentioned embodiments are only preferred solutions of the present invention, and are not limited thereto. On this basis, targeted adjustments can be made according to actual needs, so as to obtain different implementation modes. For example, there may be multiple heat-absorbing air ducts and heat-returning air ducts, distributed at intervals in the circumferential direction of the annular cooler, and so on. Since there are many ways of possible realization, it is not necessary to give examples one by one here.

Generally, the temperature range of the high-temperature flue gas discharged from the high-temperature zone of the ring cooler is 350°C-500°C. The high-temperature flue gas of ℃ is sent to the ring cooling air duct in the high temperature area through the heat recovery flue, and then sent to the trolley through the annular air duct, after heat exchange with the material on the trolley whose temperature is as high as 700-800 ℃. The flue gas temperature of this part of high-temperature flue gas can still be maintained at about 150°C after being transmitted and utilized. In this way, the temperature of the high-temperature flue gas discharged after heat exchange between the high-temperature flue gas itself with a certain temperature and the high-temperature material is lower than that of the original ring. In the high temperature zone of the cooler, the temperature of the hot flue gas discharged after directly using the cold air to cool the material is much higher. When the flue gas is reused, when the flue gas reaches a certain temperature (such as 350°C), the amount of heat energy extracted from the flue gas will increase a lot every time the flue gas temperature increases. Therefore, after circulation, the high-temperature flue gas collected in the high-temperature zone of the annular cooler can effectively improve the efficiency of flue gas reuse.

The utility model uses the same method to collect the medium-temperature flue gas discharged from the middle-temperature zone of the annular cooler through the second annular cooling cover 8, and utilizes this part of the medium-temperature flue gas as low-temperature waste heat ORC to generate electricity. After heat exchange, the hot flue gas enters the sintering The hot flue gas circulation system of the machine is sent to the material surface of the sintering machine (not shown in the figure).

The utility model also collects the flue gas discharged from the low-temperature area of the ring cooler at the same time, and sends the part of the flue gas to the front two cooling fans, and then blows it into the annular main air duct for cascade utilization, reducing the external emission of waste gas and protecting the environment. .

The annular cooler provided by the utility model has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present utility model, and the descriptions of the above embodiments are only used to help understand the core idea of the present utility model. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the utility model, some improvements and modifications can also be made to the utility model, and these improvements and modifications also fall into the protection of the claims of the utility model. within range.

Claims (12)

1. A flue gas cascade recycling circular cooler, characterized in that it comprises: The first annular cooling hood arranged on the high-temperature area of the annular cooler for collecting flue gas is connected to the first heat-absorbing air duct of the high-temperature flue gas heat recovery device, and is connected to the high-temperature flue gas heat The recovery device and the cooling air duct in the high temperature area of the annular cooler and/or the first return air duct of the cooling fan in the high temperature area of the annular cooler; The second annular cooling hood arranged on the middle temperature zone of the annular cooler for collecting flue gas is connected to the second annular cooling hood and the second heat-absorbing air duct of the medium-temperature flue gas heat recovery device, and is connected to the heat of the medium-temperature flue gas. The heat supply air pipe of the recovery device and the flue gas circulation system of the sintering machine; An exhaust tube arranged on the low temperature zone of the annular cooler for collecting and transporting flue gas, the exhaust tube is connected to the cooling fan in the middle temperature zone of the annular cooler and/or the cooling fan in the low temperature zone of the annular cooler. 2. The flue gas cascade recycling circular cooler according to claim 1, characterized in that, it also includes a third suction pipe connecting the first circular cooling hood and/or the second circular cooling hood with the ignition furnace of the sintering machine. hot air duct. 3. The flue gas cascade recycling circular cooler according to claim 1, characterized in that the high-temperature flue gas heat recovery device is a waste heat boiler capable of recovering heat energy of high-temperature flue gas to generate steam. 4. The flue gas cascade recycling circular cooler according to claim 1, characterized in that the medium-temperature flue gas heat recovery device is a low-temperature waste heat power generation system capable of recovering the heat energy of the medium-temperature flue gas to generate electricity. 5. The flue gas cascade recycling circular cooler according to claim 1, characterized in that, the flue gas circulation system of the sintering machine includes a flue gas hood arranged on the surface of the sintering machine trolley, and the flue gas The flue gas circulation duct communicated with the hood and the flue gas circulation fan arranged in the flue gas circulation duct, and the hot air supply duct is connected to the flue gas circulation fan. 6. The flue gas cascade recycling annular cooler according to claim 1, characterized in that, it also includes a first unit for transporting the flue gas to the dust removal system at the tail of the annular cooler at the receiving and discharging dust removal points of the annular cooler. Four heat-absorbing air ducts. 7. The flue gas cascade recycling circular cooler according to claim 6, characterized in that the tail dust removal system is provided with a bag filter. 8. The flue gas cascade recycling annular cooler according to any one of claims 1 to 7, wherein the annular cooler is provided with at least three first rings for collecting flue gas in the high temperature zone The cold cover, the radial end face of the first annular cold cover is a door shape, and the circumferential length is equivalent to the length of the high temperature zone of the annular cooler, and the first annular cold cover is covered in the high temperature area of the annular cooler At the position of the trolley, the top end surface is provided with a smoke exhaust port connected to a high-temperature flue gas heat recovery device. 9. The flue gas cascade recycling annular cooler according to any one of claims 1 to 7, characterized in that, the annular cooler is provided with at least two second rings for collecting flue gas in the middle temperature zone The cold cover, the radial end face of the second annular cold cover is door-shaped, and the circumferential length is equivalent to the length of the middle temperature zone of the annular cooler. At the position of the trolley, the top end surface is provided with a smoke exhaust port connected to a medium-temperature flue gas heat recovery device. 10. The annular cooler for flue gas cascade recycling according to claim 1, wherein the exhaust tube is a circular hollow structure, and the circumferential length of the covered area is equal to the length of the low temperature zone of the annular cooler. quite. 11. The circular cooler for flue gas cascade recycling according to claim 10, characterized in that, there are three cooling fans between the exhaust cylinder and the cooling fan in the middle temperature zone of the circular cooler and/or the cooling fan in the low temperature zone of the circular cooler. The first passage of the three-way pipe is connected to the exhaust cylinder, the second passage of the three-way pipe is the normal temperature air inlet, and the third passage of the three-way pipe is connected to the cooling fan in the middle temperature zone of the ring cooler And/or the cooling fan in the low temperature zone of the ring cooler. 12. The flue gas cascade recycling annular cooler according to claim 11, characterized in that, the first passage of the three-way pipe fitting is provided with a thermal expansion and contraction compensator and a first electric valve, and the three-way A second electric valve is arranged on the second passage of the pipe fitting.