System and method for deeply recycling waste heat of rotary hearth furnace

Abstract

The invention belongs to the technical field of ferrous metallurgy, and relates to a rotary hearth furnace waste heat deep recycling system and method.The system comprises a rotary hearth furnace, a rotary hearth furnace waste heat boiler, a flue gas furnace, a flue gas furnace waste heat boiler, a steam superheater, a green pellet drying machine, a discharging machine, a cylindrical cooling machine, a smoke pipe, a water pipe and a steam pipeline; the rotary hearth furnace is sequentially connected with the rotary hearth furnace waste heat boiler and the green pellet dryer through smoke pipes; the flue gas furnace is sequentially connected with a flue gas furnace waste heat boiler, a steam superheater and a green pellet dryer through a flue pipe; the rotary hearth furnace is connected with the cylindrical cooler through the discharging machine; a cooling water inlet of the cylindrical cooler is connected with external cooling water, and a water outlet of the cylindrical cooler is connected with the rotary hearth furnace waste heat boiler and the flue gas furnace waste heat boiler through water pipes; steam outlets of the rotary hearth furnace waste heat boiler, the flue gas furnace waste heat boiler and the cylindrical cooler are all connected with a steam superheater through steam pipelines, and the steam superheater is provided with a high-temperature steam outlet connected with the outside.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and relates to a system and method for deep recovery and utilization of waste heat from a rotary hearth furnace. Background Art

[0002] As an innovative metallurgical technology, the rotary hearth furnace process has shown a wide range of application prospects in the field of iron and steel metallurgy. This process uses a large amount of iron-containing dust, sludge and other solid wastes generated in the steel production process as raw materials, and transforms these wastes into valuable resources through a series of sophisticated pretreatment steps, including crushing, screening, pelletizing and drying. The pretreated raw materials are evenly arranged in the rotary hearth furnace. The heat generated by the combustion of fuel in the furnace is used to promote the reduction reaction between carbon and metal oxides, thereby reducing the metal oxides to metal elements. After cooling and discharging, the valuable elements in them can be recovered. The rotary hearth furnace process not only has strong raw material adaptability and can process various types of iron-containing wastes, but also has obvious environmental advantages, which helps to reduce environmental pollution and resource waste. At the same time, its production efficiency is relatively high, which can meet the urgent needs of the iron and steel metallurgical industry for efficient and environmentally friendly production technologies.

[0003] However, despite the many advantages of the rotary hearth furnace process, there are still major limitations in the utilization of waste heat. These limitations are mainly reflected in the following aspects:

[0004] First, high-temperature metal pellets release a lot of heat during the cooling process. Currently, this heat is mainly absorbed by cooling water and discharged into the atmosphere through cooling towers. This treatment method not only wastes energy, but also increases the heat load on the environment. How to effectively recover and utilize this part of heat has become one of the urgent problems to be solved in the rotary hearth furnace process.

[0005] Secondly, the recovery and utilization of the waste heat of the flue gas from the rotary hearth furnace is also insufficient. The flue gas temperature after absorbing heat in the waste heat boiler of the rotary hearth furnace is still as high as 150℃~200℃. However, only a small part of this flue gas is used in the drying process of green balls, and most of the rest is directly discharged into the atmosphere. This is obviously a huge waste of waste heat resources and also reduces the overall energy utilization efficiency of the rotary hearth furnace process.

[0006] Furthermore, the waste heat utilization rate of flue gas from flue gas furnace is also low. The high temperature flue gas produced by the flue gas furnace often needs to be mixed with low temperature flue gas to reduce the temperature before use. Although this operation simplifies the waste heat utilization system, it leads to the waste of high-grade energy and reduces the effective utilization rate of energy. How to reasonably utilize high temperature flue gas and improve the utilization rate of waste heat is the direction that the rotary hearth furnace process needs to be further optimized.

[0007] Finally, the small amount and low quality of steam generated by the waste heat recovery of the rotary hearth furnace are also an important factor restricting the utilization of waste heat. At present, the steam generated by the waste heat recovery of the rotary hearth furnace mainly comes from the waste heat boiler of the rotary hearth furnace. Due to the characteristics of the flue gas of the rotary hearth furnace, the steam temperature generated by the waste heat boiler generally does not exceed 300°C, and the amount of steam is relatively small. This severely limits the utilization scenarios of steam and makes it difficult to meet the demand for high-quality steam in industrial production.

[0008] In summary, the rotary hearth furnace process has many shortcomings in waste heat utilization, which urgently need to be improved and perfected through technological innovation and optimized design. Summary of the invention

[0009] In view of this, the purpose of the present invention is to provide a system and method for deep recovery and utilization of waste heat from a rotary hearth furnace, so that the waste heat in the rotary hearth furnace process can be recovered and utilized to the maximum extent, so as to solve the technical problems raised in the background technology.

[0010] In order to achieve the above object, the present invention provides the following technical solutions:

[0011] A rotary hearth furnace waste heat deep recovery and utilization system, comprising a rotary hearth furnace, a rotary hearth furnace waste heat boiler, a flue gas furnace, a flue gas furnace waste heat boiler, a steam superheater, a pellet dryer, a discharging machine, a cylinder cooler, a smoke pipe, a water pipe and a steam pipe;

[0012] The rotary hearth furnace is connected to the rotary hearth furnace waste heat boiler and the pellet dryer in sequence through a smoke pipe; the flue gas furnace is connected to the flue gas furnace waste heat boiler, the steam superheater and the pellet dryer in sequence through a smoke pipe; the rotary hearth furnace is connected to the drum cooler through a discharger;

[0013] The cylindrical cooler has a cooling water inlet and a water outlet, and the cooling water inlet of the cylindrical cooler is connected to external cooling water, and the water outlet of the cylindrical cooler is connected to the rotary hearth furnace waste heat boiler and the flue gas furnace waste heat boiler through a water pipe, and cooling water is input to the rotary hearth furnace waste heat boiler and the flue gas furnace waste heat boiler;

[0014] The steam outlets of the rotary hearth furnace waste heat boiler, the flue gas furnace waste heat boiler and the drum cooler are all connected to the steam superheater through a steam pipe, and the steam superheater has a high-temperature steam outlet connected to the outside to output high-temperature steam.

[0015] Furthermore, an air preheater and a gas preheater are provided between the flue gas furnace waste heat boiler and the pellet dryer, and the steam superheater, the air preheater and the gas preheater are arranged in series or in parallel.

[0016] Furthermore, a bypass water pipe is provided between the cooling water inlet and outlet of the cylindrical cooler, and a regulating valve is installed on the bypass water pipe. The water supply of the cylindrical cooler is controlled by the regulating valve to adjust the temperature of the metal pellets at the outlet of the cylindrical cooler.

[0017] Furthermore, the cylindrical cooler also has a high-temperature water inlet, and the water outlet of the cylindrical cooler is connected to the high-temperature water inlet of the cylindrical cooler through a water pipe.

[0018] Furthermore, the smoke pipe before the pellet dryer is provided with a rotary hearth furnace smoke inlet and a smoke furnace smoke inlet, which are used to mix the smoke from the rotary hearth furnace and the smoke from the smoke furnace and then send them into the pellet dryer.

[0019] Furthermore, the rotary hearth furnace waste heat boiler is used to absorb waste heat of the rotary hearth furnace flue gas and generate steam, and its heat exchange surface includes one or more of a water-cooled wall, an evaporator, and an economizer.

[0020] Furthermore, the flue gas furnace waste heat boiler is used to absorb waste heat of flue gas from the flue gas furnace and generate steam, and its heat exchange surface includes one or more of a water-cooled wall, an evaporator, and an economizer.

[0021] Furthermore, a settling chamber and a dust collector are respectively provided before and after the rotary hearth furnace waste heat boiler.

[0022] Furthermore, a fan is provided between the dust collector and the green ball dryer.

[0023] A method for deep recovery and utilization of waste heat from a rotary hearth furnace, based on the system, is characterized by comprising the following steps:

[0024] The high-temperature metal pellets produced by the rotary hearth furnace are sent to a drum cooler through a discharging machine, and the heat of the high-temperature metal pellets is recovered by cooling water to generate high-temperature hot water and steam;

[0025] The high-temperature flue gas generated by the rotary hearth furnace is treated by the rotary hearth furnace waste heat boiler and then sent to the green ball dryer;

[0026] The high-temperature flue gas generated by the flue gas furnace is sent to the green ball dryer after the waste heat is recovered step by step through the flue gas furnace waste heat boiler and steam superheater;

[0027] The high-temperature hot water generated by the drum cooler is sent to the rotary hearth furnace waste heat boiler and the flue gas furnace waste heat boiler respectively. After the steam is generated, it is sent to the steam superheater through the steam pipeline, further heated into high-temperature steam, and the high-temperature steam is output outside the system.

[0028] The beneficial effects of the present invention are:

[0029] The present invention proposes a system and method for deep recovery and utilization of waste heat from a rotary hearth furnace. By integrating the recovery processes of waste heat from high-temperature metal pellets, waste heat from flue gas from a rotary hearth furnace, and waste heat from flue gas from a flue gas furnace, the energy utilization efficiency in the iron and steel metallurgical process is significantly improved. In traditional processes, the cooling of high-temperature metal pellets and the emission of flue gas result in a large amount of heat loss. This system achieves a cascade utilization of waste heat through the optimized design of a cylindrical cooler and a multi-stage waste heat boiler. The flue gas emission temperature is reduced from 200°C in traditional processes to 110°C to 130°C, the steam output is increased by about 30%, and the energy utilization efficiency is increased by about 20%. This multi-level recovery method not only reduces energy waste, but also reflects the innovativeness of the technical solution, providing a new path for efficient waste heat utilization in the steel industry.

[0030] In terms of waste heat recovery from high-temperature metal pellets, this system effectively converts the heat released during cooling into high-temperature hot water and steam through a cylindrical cooler, achieving both environmental and economic benefits. Traditional cooling methods often cause thermal pollution through water cooling discharge, but this design recovers the heat and sends it to the waste heat boiler for further utilization, avoiding heat loss. This highly practical design is suitable for steel companies of different sizes. It not only reduces dependence on external energy, but also improves the overall system efficiency through multi-level utilization of heat, demonstrating the practical application value of the technical solution.

[0031] This system realizes full and efficient recycling of waste heat from flue gas from rotary hearth furnaces and flue gas furnaces. The high-temperature flue gas generated by the rotary hearth furnace is cooled by the waste heat boiler and steam is generated, and the remaining heat is used for drying the raw balls; the flue gas from the flue gas furnace is recycled step by step through a dedicated waste heat boiler and a steam superheater. This hierarchical utilization method avoids the energy waste caused by traditional cooling and significantly improves the utilization rate of flue gas waste heat. Compared with traditional processes, this system achieves efficient conversion of waste heat by optimizing the flue gas flow path and heat distribution, highlighting its innovation and practicality.

[0032] In addition, this system has greatly improved the steam production and quality, and achieved the adjustability of the outlet temperature of the metal pellets. Through the steam superheater, the recovered steam temperature reaches 400℃~440℃, and the pressure is increased to 2.5~3.8MPa, far exceeding the 300℃ of the traditional process, meeting the demand for high-quality steam in industrial production. At the same time, the drum cooler is equipped with a bypass water pipe and a regulating valve, so that the outlet temperature of the metal pellets can be flexibly adjusted according to process requirements. This combination of high-quality steam and temperature controllability not only improves the economic benefits of energy utilization, but also enhances the adaptability of the system, providing an efficient and flexible waste heat recovery solution for the steel and metallurgical industry.

[0033] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 It is a schematic diagram of the layout of a rotary hearth furnace waste heat deep recovery and utilization system in an embodiment.

[0036] Figure numerals: 1-rotary hearth furnace; 2-rotary hearth furnace waste heat boiler; 3-flue gas furnace; 4-flue gas furnace waste heat boiler; 5-steam superheater; 6-air preheater; 7-gas preheater; 8-raw ball dryer; 9-discharger; 10-discharger; 11-sedimentation chamber; 12-dust collector; 13-fan; 14-regulating valve; 15-smoke pipe; 16-water pipe; 17-steam pipe. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0038] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0039] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0040] Example 1

[0041] See also Figure 1 It is a basic rotary hearth furnace waste heat deep recovery and utilization system, suitable for small and medium-sized steel and metallurgical enterprises, with a simple structure and easy implementation.

[0042] The system includes a rotary hearth furnace 1, a rotary hearth furnace waste heat boiler 2, a flue gas furnace 3, a flue gas furnace waste heat boiler 4, a steam superheater 5, a pellet dryer 8, a discharger 9, a cylinder cooler 10, a smoke pipe 15, a water pipe 16 and a steam pipe 17. In addition, the system is equipped with a settling chamber 11, a dust collector 12 and a fan 13 to treat the flue gas from the rotary hearth furnace. The cylinder cooler 10 is provided with a bypass water pipe 16 connecting the cooling water inlet and outlet and a regulating valve 14 arranged on the bypass water pipe 16 for adjusting the cooling water flow.

[0043] The rotary hearth furnace 1 is connected to the rotary hearth furnace waste heat boiler 2 and the pellet dryer 8 in sequence through the smoke pipe 15; the flue gas furnace 3 is connected to the flue gas furnace waste heat boiler 4, the steam superheater 5 and the pellet dryer 8 in sequence through the smoke pipe 15; the rotary hearth furnace 1 is connected to the drum cooler 10 through the discharger 9;

[0044] The cylindrical cooler 10 has a cooling water inlet and a water outlet, and the cooling water inlet of the cylindrical cooler 10 is connected to external cooling water, and the water outlet of the cylindrical cooler 10 is connected to the rotary hearth furnace waste heat boiler 2 and the flue gas furnace waste heat boiler 4 through a water pipe 16, and cooling water is input to the rotary hearth furnace waste heat boiler 2 and the flue gas furnace waste heat boiler 4;

[0045] The steam outlets of the rotary hearth furnace waste heat boiler 2, the flue gas furnace waste heat boiler 4 and the drum cooler 10 are all connected to the steam superheater 5 through the steam pipe 17, and the steam superheater 5 has a high-temperature steam outlet connected to the outside to output high-temperature steam.

[0046] The system operation process is as follows:

[0047] High temperature metal pellet waste heat recovery:

[0048] The high-temperature metal pellets produced by the rotary hearth furnace 1 have a temperature of about 1000°C and are fed into the drum cooler 10 through the discharger 9. External cooling water, with an initial temperature of about 60°C, enters through the cooling water inlet of the drum cooler 10 to exchange heat with the high-temperature metal pellets. After absorbing heat, part of the cooling water becomes high-temperature hot water with a temperature of about 100°C and is output from the outlet; the other part generates medium-pressure steam in the drum cooler 10 with a pressure of about 2.8MPa and a temperature of about 232°C.

[0049] The high-temperature hot water is divided into two paths through the water pipe 16 and respectively sent to the rotary hearth furnace waste heat boiler 2 and the flue gas furnace waste heat boiler 4. By adjusting the regulating valve 14 on the bypass water pipe 16, the cooling water flow rate is controlled to stabilize the temperature of the metal pellets at the outlet of the drum cooler 10 at about 120°C, which is convenient for subsequent processing.

[0050] Rotary hearth furnace flue gas waste heat recovery:

[0051] The high-temperature flue gas generated by the rotary hearth furnace 1 has a temperature of about 1000°C and enters the settling chamber 11 through the smoke pipe 15. After removing some dust, it enters the rotary hearth furnace waste heat boiler 2. In the rotary hearth furnace waste heat boiler 2, the flue gas exchanges heat with high-temperature hot water, and the temperature drops to about 180°C, generating medium-pressure steam with a pressure of about 2.8MPa and a temperature of about 232°C. The flue gas is then purified by the dust collector 12 and sent to the green ball dryer 8 through the fan 13 for drying the green balls.

[0052] Flue gas waste heat recovery from flue gas furnace:

[0053] The high-temperature flue gas generated by the flue gas furnace 3 has a temperature of about 1250°C and enters the flue gas furnace waste heat boiler 4 through the smoke pipe 15. In the flue gas furnace waste heat boiler 4, the flue gas exchanges heat with high-temperature hot water to generate medium-pressure steam with a pressure of about 2.8MPa and a temperature of about 232°C, and the flue gas temperature drops to about 650°C. Subsequently, the flue gas enters the steam superheater 5 and the air preheater 6. In the steam superheater 5, the flue gas heats the steam into high-temperature steam with a pressure of about 2.5MPa and a temperature of about 400°C; in the air preheater 6, the air required by the rotary hearth furnace 1 is preheated from 25°C to 450°C; the flue gas temperature drops to about 350°C, and is mixed with the flue gas of the rotary hearth furnace and sent to the green ball dryer 8.

[0054] Steam output:

[0055] The steam generated by the rotary hearth furnace waste heat boiler 2, the flue gas furnace waste heat boiler 4 and the drum cooler 10 is collected to the steam superheater 5 through the steam pipe 17, and is output from the high-temperature steam outlet after heating for use in other processes in the plant, such as heating or power generation.

[0056] In this embodiment, the waste heat of metal pellets is recovered by the drum cooler 10, and the waste heat boiler 2 of the rotary hearth furnace and the waste heat boiler 4 of the flue gas furnace are used to recover the waste heat of flue gas, and finally high-temperature steam is generated. The flue gas discharge temperature is reduced from 200°C in the traditional process to 130°C. After calculation, the steam output is increased by about 40%, and the steam temperature reaches 400°C.

[0057] Example 2

[0058] See also Figure 1 , is an enhanced rotary hearth furnace waste heat deep recovery and utilization system. This embodiment adds an air preheater 6 and a gas preheater 7 on the basis of embodiment 1, and includes a rotary hearth furnace 1, a rotary hearth furnace waste heat boiler 2, a flue gas furnace 3, a flue gas furnace waste heat boiler 4, a steam superheater 5, an air preheater 6, a gas preheater 7, a pellet dryer 8, a discharging machine 9, a cylinder cooler 10, a settling chamber 11, a dust collector 12, a fan 13, a smoke pipe 15, a water pipe 16 and a steam pipe 17. The cylinder cooler 10 is provided with a bypass water pipe 16 connecting the cooling water inlet and the water outlet and a regulating valve 14 arranged on the bypass water pipe 16 for adjusting the cooling water flow rate. The smoke pipe 15 in front of the pellet dryer 8 is provided with a rotary hearth furnace smoke inlet and a flue gas furnace smoke inlet, so as to mix the rotary hearth furnace smoke and the flue gas furnace smoke in advance before sending them into the pellet dryer 8.

[0059] The system operation process is as follows:

[0060] High temperature metal pellet waste heat recovery:

[0061] The high-temperature metal pellets produced by the rotary hearth furnace 1 have a temperature of about 1000°C and are fed into the drum cooler 10 through the discharging machine 9. External cooling water, with an initial temperature of about 25°C, enters the drum cooler 10 and absorbs heat to generate high-temperature hot water with a temperature of about 95°C and medium-pressure steam with a pressure of about 4.2MPa and a temperature of about 253°C. The high-temperature hot water is divided into three paths through the water pipe 16: one path returns to the high-temperature water inlet of the drum cooler 10 to continue to generate steam; the other two paths are fed into the rotary hearth furnace waste heat boiler 2 and the flue gas furnace waste heat boiler 4. The cooling water flow is controlled by the regulating valve 14 to keep the outlet temperature of the metal pellets at about 80°C.

[0062] Rotary hearth furnace flue gas waste heat recovery:

[0063] The high-temperature flue gas generated by the rotary hearth furnace 1 has a temperature of about 1000°C and enters the settling chamber 11 through the flue pipe 15. After dust removal, it enters the rotary hearth furnace waste heat boiler 2. The rotary hearth furnace waste heat boiler 2 uses water-cooled walls, evaporators and economizer heat exchange surfaces. The flue gas exchanges heat with high-temperature hot water, and the temperature drops to about 170°C, generating medium-pressure steam with a pressure of about 4.2MPa and a temperature of about 253°C. The flue gas is purified by the dust collector 12 and sent to the flue pipe 15 in front of the green ball dryer 8 by the fan 13 to mix with the flue gas from the flue gas furnace.

[0064] Flue gas waste heat recovery from flue gas furnace:

[0065] The high-temperature flue gas generated by the flue gas furnace 3 has a temperature of about 1250°C and enters the flue gas furnace waste heat boiler 4 through the smoke pipe 15. The water-cooled wall and the economizer heat exchange surface are used to generate medium-pressure steam with a pressure of about 4.2MPa and a temperature of about 253°C. The flue gas temperature drops to about 750°C. Subsequently, the flue gas enters the steam superheater 5, the air preheater 6 and the coal gas preheater 7 in sequence. In the steam superheater 5, the flue gas heats the steam into high-temperature steam with a pressure of about 3.8MPa and a temperature of about 440°C; in the air preheater 6, the air required by the rotary hearth furnace 1 is preheated from 25°C to 450°C; in the coal gas preheater 7, the coal gas is preheated from 20°C to 250°C. The flue gas temperature drops to about 350°C, and is mixed with the flue gas of the rotary hearth furnace and sent to the green ball dryer 8.

[0066] Steam output and air gas utilization:

[0067] The high-temperature steam outputted by the steam superheater 5 is supplied to the heat users in the plant through the external outlet. The preheated air and gas are sent back to the rotary hearth furnace 1 to improve the combustion efficiency.

[0068] In this embodiment, the air preheater 6 and the gas preheater 7 are used to realize multi-stage utilization of flue gas waste heat, and the flue gas discharge temperature is reduced from 200° C. in the traditional process to 110° C. After calculation, the steam output is increased by about 32%, and the steam temperature reaches 440° C. Preheating air and gas further reduces the fuel consumption of the rotary hearth furnace 1, and saves energy significantly.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A rotary hearth furnace waste heat deep recovery and utilization system, characterized by: It comprises a rotary hearth furnace (1), a rotary hearth furnace waste heat boiler (2), a flue gas furnace (3), a flue gas furnace waste heat boiler (4), a steam superheater (5), a pellet dryer (8), a discharger (9), a drum cooler (10), a smoke pipe (15), a water pipe (16) and a steam pipe (17); The rotary hearth furnace (1) is connected to the rotary hearth furnace waste heat boiler (2) and the pellet dryer (8) in sequence through a smoke pipe (15); the flue gas furnace (3) is connected to the flue gas furnace waste heat boiler (4), the steam superheater (5) and the pellet dryer (8) in sequence through a smoke pipe (15); the rotary hearth furnace (1) is connected to the drum cooler (10) through a discharger (9); The cylindrical cooler (10) has a cooling water inlet and a cooling water outlet, and the cooling water inlet of the cylindrical cooler (10) is connected to external cooling water, and the outlet of the cylindrical cooler (10) is connected to the rotary hearth furnace waste heat boiler (2) and the flue gas furnace waste heat boiler (4) through a water pipe (16), so as to input cooling water into the rotary hearth furnace waste heat boiler (2) and the flue gas furnace waste heat boiler (4); The steam outlets of the rotary hearth furnace waste heat boiler (2), the flue gas furnace waste heat boiler (4) and the drum cooler (10) are all connected to the steam superheater (5) via a steam pipe (17), and the steam superheater (5) has a high-temperature steam outlet connected to the outside to output high-temperature steam.

2. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1 is characterized in that: An air preheater (6) and a gas preheater (7) are also provided between the flue gas furnace waste heat boiler (4) and the green pellet dryer (8), and the steam superheater (5), the air preheater (6), and the gas preheater (7) are arranged in series or in parallel.

3. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1 is characterized in that: A bypass water pipe (16) is provided between the cooling water inlet and outlet of the cylindrical cooler (10), and a regulating valve (14) is installed on the bypass water pipe (16). The regulating valve (14) controls the water supply of the cylindrical cooler (10) to adjust the temperature of the metal pellets at the outlet of the cylindrical cooler (10).

4. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1 is characterized in that: The cylindrical cooler (10) also has a high-temperature water inlet, and the water outlet of the cylindrical cooler (10) is connected to the high-temperature water inlet of the cylindrical cooler (10) through a water pipe (16).

5. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1 is characterized in that: The smoke pipe (15) before the green ball dryer (8) is provided with a rotary hearth furnace smoke inlet and a smoke furnace smoke inlet, which are used to mix the smoke from the rotary hearth furnace (1) and the smoke from the smoke furnace (3) and then send them into the green ball dryer (8).

6. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1, characterized in that: The rotary hearth furnace waste heat boiler (2) is used to absorb waste heat from the rotary hearth furnace flue gas and generate steam, and its heat exchange surface includes one or more of a water-cooled wall, an evaporator, and an economizer.

7. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1, characterized in that: The flue gas furnace waste heat boiler (4) is used to absorb waste heat from flue gas in the flue gas furnace and generate steam, and its heat exchange surface includes one or more of a water-cooled wall, an evaporator, and an economizer.

8. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1, characterized in that: A settling chamber (11) and a dust collector (12) are respectively provided before and after the rotary hearth furnace waste heat boiler (2).

9. The rotary hearth furnace waste heat deep recovery and utilization system according to claim 1, characterized in that: A fan (13) is also provided between the dust collector (12) and the green ball dryer (8).

10. A method for deep recovery and utilization of waste heat from a rotary hearth furnace, based on the system described in any one of claims 1 to 9, characterized in that: The following steps are involved: The high-temperature metal pellets produced by the rotary hearth furnace (1) are sent to a cylindrical cooler (10) through a discharging machine (9), and the heat of the high-temperature metal pellets is recovered by cooling water to generate high-temperature hot water and steam; The high-temperature flue gas generated by the rotary hearth furnace (1) is treated by the rotary hearth furnace waste heat boiler (2) and then sent to the pellet dryer (8); The high-temperature flue gas generated by the flue gas furnace (3) is sent to a pellet dryer (8) after the waste heat is recovered step by step through a flue gas furnace waste heat boiler (4) and a steam superheater (5); The high-temperature hot water generated by the drum cooler (10) is respectively sent to the rotary hearth furnace waste heat boiler (2) and the flue gas furnace waste heat boiler (4), and after the steam is generated, it is sent to the steam superheater (5) through the steam pipeline (17), and is further heated to high-temperature steam, and the high-temperature steam is output to the outside of the system.

Images