A high-efficiency cascade comprehensive utilization system and method for sintering waste heat

Abstract

The present invention discloses a system and method for the efficient cascade comprehensive utilization of sintering waste heat, belonging to the technical field of ironmaking, steam turbines and turbine devices; the system includes a cooler for cooling high-temperature minerals, the cooler has two flue gas pipes, the flue gas ducts include a high-temperature flue gas pipe and a low-temperature flue gas pipe, wherein the high-temperature flue gas pipe with a higher temperature is connected to the steam turbine heat system, and the other low-temperature flue gas pipe with a lower temperature is connected to the ORC turbine heat system; the system and method for the efficient cascade comprehensive utilization of sintering waste heat of the present invention realize the hierarchical utilization of high-temperature flue gas and low-temperature flue gas through the design of the cooler, fully realize the operation of the steam turbine and the operation of the turbine, and can be fully utilized in terms of thermal energy according to the different temperatures of the flue gas.

Description

Technical Field

[0001] The present invention relates to a system and method for high-efficiency cascade comprehensive utilization of sintering waste heat, belonging to the technical field of ironmaking, steam turbines and turbine devices. Background Art

[0002] The sintering process is a critical step in steel production, accounting for approximately 10% of the industry's total energy consumption. Reducing the overall energy consumption of the sintering process is a key research topic for relevant technical personnel. During sinter production, the sensible heat of the sintered ore, which accounts for nearly 45% of the total heat, is cooled by air within the cooler. The temperature of the hot exhaust gas discharged by the cooler varies depending on the cooling area. Effectively utilizing the waste heat from the cooler flue gas and improving its efficiency is an effective way to save energy and reduce emissions in the steel industry.

[0003] Currently, cooler flue gas above 300°C is widely utilized. A typical method is to feed it into a waste heat boiler (HRSG), which generates medium- or low-pressure steam. This steam then drives a steam turbine, which in turn drives a generator to generate electricity. Cooler flue gas below 300°C can be utilized in a variety of ways, such as using it for winter heating in northern China. ORC (Organic Rankine Cycle) technology is a recently emerging technology that uses a relatively low-boiling-point organic fluid to absorb cooler flue gas below 300°C in a heat exchanger. This then drives the ORC turbine to expand and generate work, thus recovering the low-temperature waste heat.

[0004] ORC technology has limited domestic application. While a single turbine has low power output, it requires a complete generator and electrical system, resulting in a high investment per unit of power. Furthermore, the cycle efficiency is low, resulting in a low return on investment. Consequently, steel companies are not very enthusiastic about implementing ORC technology.

[0005] The sintering fan is a major power consumer in the sintering process, with a single unit power output of up to 10MW. Sintering fans can be driven by either an electric motor or a steam turbine. Electric motor drive requires a motor and frequency conversion system that matches the sintering fan's power, but the system is simple and offers flexible start-up and shutdown. Steam turbine drive requires a corresponding steam-water-oil system, which is more complex and less flexible to start. However, the steam turbine's power steam can be derived from sintering waste heat, effectively converting this waste heat into kinetic energy for the sintering fan. This reduces the number of energy conversions and increases efficiency.

[0006] Therefore, a new system is needed to overcome the current problems of low investment return rate, decentralized system, high construction cost, low waste heat utilization efficiency and so on in the cascade utilization of sintering waste heat, and to improve the level of cascade utilization of sintering waste heat. Summary of the Invention

[0007] The purpose of the present invention is to provide a system and method for the efficient cascade comprehensive utilization of sintering waste heat in order to solve the above-mentioned problems, thereby reducing equipment investment and civil engineering investment and avoiding the loss of multiple energy conversions.

[0008] The technical solution adopted in the present invention is as follows:

[0009] A high-efficiency cascade comprehensive utilization system for sintering waste heat includes a cooler for cooling high-temperature minerals. The cooler has two flue gas ducts, including a high-temperature flue gas duct and a low-temperature flue gas duct. The high-temperature flue gas duct with a higher temperature is connected to a steam turbine heat system, and the low-temperature flue gas duct with a lower temperature is connected to an ORC turbine heat system.

[0010] The flue gas discharged from the high-temperature flue gas pipeline with a higher temperature is used to heat water and generate steam for use in the steam turbine heat system to perform work;

[0011] The flue gas discharged from the low-temperature flue gas pipeline with a lower temperature is used to heat the working medium, and the heat energy of the working medium is used to make the ORC turbine heat system work.

[0012] Furthermore, an energy consumption device is provided between the steam turbine heat system and the ORC turbine heat system.

[0013] Furthermore, the energy consumption device includes a coaxially arranged dual-purpose motor and a sintering fan, which are connected to the steam turbine heat system and the ORC turbine heat system at both ends through a steam turbine speed change clutch and an ORC turbine speed change clutch respectively.

[0014] Furthermore, the steam turbine heat system includes a supplementary steam turbine connected to a steam turbine speed change clutch, the inlet steam of the supplementary steam turbine comes from a waste heat boiler, the heat of the waste heat boiler comes from a cooler, the flue gas heat is utilized and then discharged, the exhaust steam of the supplementary steam turbine is connected to a condenser, the condensed water generated by the condenser is transported to the waste heat boiler, and a feed water pump for increasing the condensed water pressure is also provided on the pipeline connecting the condenser and the waste heat boiler.

[0015] Furthermore, the waste heat boiler is a dual-pressure waste heat boiler, and the dual-pressure waste heat boiler has two steam outlet ports, wherein the steam with a relatively high temperature enters the steam supply turbine through the medium-pressure steam inlet pipe, and the steam with a relatively low temperature is connected to the middle part of the steam supply turbine through the low-pressure steam supply pipe.

[0016] Furthermore, the ORC turbine heat system includes an ORC turbine connected to an ORC turbine speed change clutch. The heat source of the ORC turbine comes from the ORC boiler, and the heat source of the ORC boiler comes from the low-temperature flue gas pipe. The flue gas enters the ORC boiler through the low-temperature flue gas pipe and is discharged through the chimney. After heat exchange in the ORC boiler, the working fluid enters the ORC turbine to perform work, and is discharged into the ORC condenser after performing work. Then, it enters the ORC boiler through the ORC condenser. An ORC working fluid pump is also provided on the pipeline connecting the ORC condenser and the ORC boiler.

[0017] Furthermore, the exhaust end of the waste heat boiler for exhausting flue gas is connected to the low-temperature flue gas duct and is mixed with the low-temperature flue gas in the low-temperature flue gas duct.

[0018] A method for high-efficiency cascade comprehensive utilization of sintering waste heat, using the above-mentioned high-efficiency cascade comprehensive utilization system for sintering waste heat, comprises the following steps:

[0019] The high-temperature mineral is cooled in the cooler, and high-temperature flue gas and low-temperature flue gas are generated at different locations. The high-temperature flue gas enters the waste heat boiler along its high-temperature flue gas pipe, where it fully exchanges heat with water vapor. After the heat exchange, the low-temperature flue gas is discharged from the boiler along the low-temperature flue gas pipe;

[0020] The low-temperature flue gas from the exhaust of the waste heat boiler is mixed with the low-temperature flue gas from the cooler. The mixed low-temperature flue gas enters the ORC boiler, where it fully exchanges heat with the working medium. Finally, the exhaust gas is discharged from the ORC boiler and discharged into the atmosphere through the chimney.

[0021] In terms of the steam cycle, medium-pressure steam from the waste heat boiler enters the supplementary steam turbine along the medium-pressure steam inlet pipe, driving the supplementary steam turbine to rotate and generate power. At the same time, low-pressure steam from the waste heat boiler enters the middle part of the supplementary steam turbine along the low-pressure supplementary steam pipe, feeding the turbine to generate power. The turbine's speed-changing clutch drives the dual-purpose motor and the rotating shaft of the sintering fan. After completing energy conversion in the turbine, the steam is discharged into the condenser along the exhaust pipe, condensed into water in the condenser, and re-enters the waste heat boiler through the feedwater pump and pipeline, completing the entire steam cycle.

[0022] In terms of the working fluid cycle, the working fluid absorbs heat in the ORC boiler, increasing its parameters before entering the ORC turbine along the working fluid inlet duct. There, the working fluid expands and produces work, driving the ORC turbine to rotate and output power. The ORC turbine's variable speed clutch drives the dual-purpose motor and the rotating shaft of the sintering blower. The energy-converted working fluid enters the ORC condenser, condenses into a liquid state, and is then pumped into the ORC boiler via the ORC working fluid pump, completing the entire organic working fluid cycle.

[0023] Furthermore, when the induction steam turbine fails to start or fails, the turbine speed change clutch disengages, isolating the induction steam turbine from the entire shafting system. At this point, the sintering fan, dual-purpose motor, and ORC turbine achieve power balance.

[0024] When the ORC turbine fails to start or fails, the ORC turbine speed change clutch disengages, and the ORC turbine is isolated from the entire shaft system. At this time, the steam injection turbine, dual-purpose motor, and sintering fan achieve power balance;

[0025] When all equipment is operating normally, both clutches are engaged, and the steam turbine, ORC turbine, dual-purpose motor, and sintering fan achieve power balance.

[0026] Furthermore, when the output power of the ORC turbine and / or the air-supplemented steam turbine is greater than the power of the sintering fan, the dual-purpose motor functions as a generator and the electric energy is input into the grid;

[0027] When the output power of the ORC turbine and / or the air-supplemented steam turbine is less than that of the sintering fan, the dual-purpose motor acts as an electric motor and absorbs electric energy from the power grid to make up for the power difference between the power source and the sintering fan.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] 1. The present invention provides a high-efficiency cascade comprehensive utilization system and method for sintering waste heat. Through the design of the cooler, high-temperature flue gas and low-temperature flue gas are utilized in stages, fully realizing the operation of the steam turbine and the turbine. According to the different temperatures of the flue gas, the thermal energy can be fully utilized.

[0030] 2. The present invention provides a high-efficiency cascaded comprehensive utilization system and method for sintering waste heat. This system combines a steam turbine-driven generator, an ORC turbine-driven generator, and an electric motor into a single device, a dual-purpose motor. This reduces equipment investment and avoids multiple conversions of electrical energy, thus avoiding energy losses from multiple conversions. The ORC system does not need to be equipped with a separate generator and electrical system, thus reducing ORC system investment and improving the return on investment.

[0031] 3. The present invention provides a system and method for the efficient cascade comprehensive utilization of sintering waste heat. The output of the steam turbine and ORC turbine first drives the sintering fan, and the remaining power drives the dual-purpose motor to generate electricity. Compared with generating electricity using the full power of the steam turbine and ORC turbine, the generated power is smaller, the investment in power transmission and transformation equipment will be reduced, and the project construction cost will be saved. The thermal power station, sintering fan station, and ORC plant are integrated, saving the project civil construction cost, while optimizing the operating personnel configuration and reducing the number of operation and maintenance personnel. Compared with traditional steam traction, the dual-purpose motor in this system can be instantly converted into an electric motor, which continues to drive the sintering fan under steam turbine accident conditions, thereby improving the stability of the sintering fan operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0033] Figure 1 It is a structural schematic diagram of the present invention.

[0034] Markings in the figure: 1-steam supply turbine, 2-steam turbine speed change clutch, 3-dual-purpose motor, 4-sintering fan, 5-ORC turbine speed change clutch, 6-working fluid inlet pipe, 7-ORC turbine, 8-ORC boiler, 9-chimney, 10-low-pressure steam supply pipe, 11-medium-pressure steam inlet pipe, 12-waste heat boiler, 13-feed water pipe, 14-feed water pump, 15-exhaust pipe, 16-condenser, 17-high-temperature flue gas pipe, 18-exhaust pipe, 19-cooler, 20-low-temperature flue gas pipe, 21-ORC condenser, 22-working fluid exhaust pipe, 23-ORC working fluid pump, 24-working fluid inlet boiler pipe. DETAILED DESCRIPTION

[0035] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0036] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0037] Example 1

[0038] A high-efficiency cascade comprehensive utilization system of sintering waste heat, such as Figure 1 As shown, a cooler 19 for high-temperature mineral cooling is included. The cooler 19 has two flue gas ducts, including a high-temperature flue gas duct 17 and a low-temperature flue gas duct 20. The high-temperature flue gas duct 17 with a higher temperature is connected to the steam turbine heat system, and the low-temperature flue gas duct 20 with a lower temperature is connected to the ORC turbine heat system.

[0039] The flue gas discharged from the high-temperature flue gas pipe 17 with a higher temperature is used to heat water and generate steam for use in the steam turbine heat system to perform work;

[0040] The flue gas discharged from the low-temperature flue gas duct 20 with a lower temperature is used to heat the working medium, and the heat energy of the working medium is used to generate work in the ORC turbine heat system.

[0041] In this embodiment, unlike the traditional structural design, in this structural design, the cooler 19 (sintering cooler 19) is used to generate flue gases of different temperatures when cooling high-temperature minerals. A two-stage heat utilization system is used to utilize the flue gases in different temperature ranges, thereby fully utilizing the flue gases and fully utilizing the energy, thereby obtaining a more efficient energy utilization rate. In addition, in terms of structural design, the on-site equipment layout can be further compacted, and the equipment investment cost can be effectively reduced, thereby achieving better economic performance and better energy consumption utilization.

[0042] Based on the above-mentioned specific structural design, as a more specific design, an energy consumption device is provided between the steam turbine heat system and the ORC turbine heat system.

[0043] Regarding the design of the aforementioned energy dissipation device, a more specific design comprises a coaxially arranged dual-purpose motor 3 and a sintering fan 4, connected at either end to the steam turbine heat system and the ORC turbine heat system via a steam turbine speed-changing clutch 2 and an ORC turbine speed-changing clutch 5, respectively. This design effectively switches the dual-purpose motor 3 based on the output power of the induction steam turbine 1 or the ORC turbine 7, prioritizing the sintering fan 4 in terms of power consumption. Furthermore, a speed-changing clutch is employed, taking into account the output power or speed of the two systems, to effectively achieve synchronized speed control and enable either or both systems to be offline or active.

[0044] Based on the design of the above-mentioned specific structure, as a more specific design, the steam turbine heat system includes a steam-assisted steam turbine 1 connected to a steam turbine speed-changing clutch 2. The steam inlet of the steam-assisted steam turbine comes from a waste heat boiler 12. The heat of the waste heat boiler 12 comes from a cooler 19. The heat of the flue gas is discharged after utilization. The exhaust steam of the steam-assisted steam turbine is connected to a condenser 16. The condensed water generated by the condenser 16 is transported to the waste heat boiler 12. A feed water pump 14 for increasing the pressure of the condensed water is also provided on the pipeline connecting the condenser 16 and the waste heat boiler 12.

[0045] As a further and more optimized design, the waste heat boiler 12 is a dual-pressure waste heat boiler 12, and the dual-pressure waste heat boiler 12 has two steam outlet ports, wherein the steam with a relatively high temperature enters the steam supply turbine 1 through the medium-pressure steam inlet pipe 11, and the steam with a relatively low temperature is connected to the middle part of the steam supply turbine 1 through the low-pressure steam supply pipe 10.

[0046] Based on the above specific structural design, as a specific design of the ORC turbine heat system, the ORC turbine heat system includes an ORC turbine 7 connected to an ORC turbine transmission clutch 5. The heat source of the ORC turbine 7 is derived from the ORC boiler 8, and the heat source of the ORC boiler 8 is derived from the low-temperature flue gas duct 20. The flue gas enters the ORC boiler 8 through the low-temperature flue gas duct 20 and is discharged through the chimney 9. After heat exchange in the ORC boiler 8, the working fluid enters the ORC turbine 7 to perform work. After performing work, it is discharged into the ORC condenser 21, passes through the ORC condenser 21, and enters the ORC boiler 8. An ORC working fluid pump 23 is also provided in the pipeline connecting the ORC condenser 21 and the ORC boiler 8.

[0047] In a further design, the exhaust end of the waste heat boiler 12 for exhausting flue gas is connected to the low-temperature flue gas duct 20 and is mixed with the low-temperature flue gas in the low-temperature flue gas duct 20.

[0048] Example 2

[0049] Based on the design of Example 1 and in combination with the design of the above structure, a method for efficient cascade comprehensive utilization of sintering waste heat is provided, comprising the following steps:

[0050] The high-temperature mineral is cooled in the cooler 19, generating high-temperature flue gas and low-temperature flue gas at different locations. The high-temperature flue gas enters the waste heat boiler 12 along its high-temperature flue gas duct 17, where it fully exchanges heat with water vapor. After the heat exchange, the low-temperature flue gas enters the low-temperature flue gas duct 20 along the flue gas exhaust duct 18 and is discharged from the boiler.

[0051] The low-temperature flue gas from the exhaust of the waste heat boiler 12 is mixed with the low-temperature flue gas from the cooler 19. The mixed low-temperature flue gas enters the ORC boiler 8, where it fully exchanges heat with the working medium. Finally, the exhaust gas is discharged from the ORC boiler 8 and discharged into the atmosphere through the chimney 9.

[0052] In terms of the steam cycle, medium-pressure steam from the waste heat boiler 12 enters the supplementary steam turbine 1 along the medium-pressure steam inlet pipe 11, driving the supplementary steam turbine 1 to rotate and generate work. At the same time, low-pressure steam from the waste heat boiler 12 enters the middle part of the supplementary steam turbine 1 along the low-pressure supplementary steam pipe 10, feeding the turbine and generating work together. The steam drives the dual-purpose motor and the rotating shaft of the sintering fan 4 through the turbine speed-changing clutch 2. After completing energy conversion in the steam turbine, the steam is discharged into the condenser 16 along the exhaust pipe 15. In the condenser 16, it condenses into water and re-enters the waste heat boiler 12 through the feedwater pump 14 and the feedwater pipe 13, completing the entire steam cycle.

[0053] In terms of the working medium circulation, the working medium absorbs heat in the ORC boiler 8, increasing its parameters, and enters the ORC turbine 7 along the working medium inlet pipe 6. The working medium expands and performs work in the ORC turbine 7, driving the ORC turbine 7 to rotate and output power. The ORC turbine speed change clutch 5 drives the rotating shaft of the dual-purpose motor and the sintering fan 4. The working medium that has completed energy conversion enters the ORC condenser 21 through the working medium exhaust pipe 22, condenses into liquid, and is then pumped into the ORC boiler 8 through the ORC working medium pump 23 and the working medium boiler inlet pipe 24, completing the entire organic working medium cycle.

[0054] Specifically, the low-temperature flue gas in cooler 19 has a temperature between 150°C and 300°C. The high-temperature flue gas, which is higher than 300°C, reaches a temperature of approximately 150°C (140°C to 160°C) after passing through waste heat boiler 12. After remixing, it can be effectively utilized in the ORC turbine heat system. More specifically, the working fluid shown is an organic working fluid.

[0055] In the above specific design, the cooler 19 (sintering cooler 19) includes but is not limited to a sintering ring cooler, a sintering belt cooler, and a sintering vertical cooler.

[0056] At the same time, the dual-purpose motor 3 can reach a speed of 3000 rpm. This allows the steam turbine and dual-purpose motor 3 to have the same speed. Only a clutch is provided between the shafts, and the transmission is instead located between the dual-purpose motor 3 and the sintering fan 4. As an equivalent configuration, the positions of the inlet steam turbine 1 and the ORC turbine in the system can be swapped.

[0057] The steam turbine and ORC turbine usually have a conventional speed of 3000 r / min, and the sintering fan 4 usually has a low speed of 1500 r / min. In order to reduce the complexity of the shaft system, the dual-purpose motor 3 and the sintering fan 4 are designed to have a low speed of 1500 r / min.

[0058] More specifically, when the induction steam turbine 1 fails to start or fails, the turbine speed change clutch 2 is disengaged, and the induction steam turbine 1 is isolated from the entire shaft system. At this time, the sintering fan 4, the dual-purpose motor 3, and the ORC turbine 7 achieve power balance.

[0059] When the ORC turbine 7 fails to start or fails, the ORC turbine speed change clutch 5 is disengaged, and the ORC turbine 7 is isolated from the entire shaft system. At this time, the steam injection turbine 1, the dual-purpose motor 3, and the sintering fan 4 achieve power balance.

[0060] When all equipment is operating normally, both clutches are engaged, and the steam-assisted steam turbine 1, the ORC turbine 7, the dual-purpose motor 3, and the sintering fan 4 achieve power balance.

[0061] On the basis of the above specific design, when the output power of the ORC turbine 7 and / or the air-supplemented steam turbine is greater than the power of the sintering fan 4, the dual-purpose motor 3 acts as a generator and the electric energy is input into the grid;

[0062] When the output power of the ORC turbine 7 and / or the air-supplementing steam turbine is less than that of the sintering fan 4 , the dual-purpose motor 3 is an electric motor that absorbs electric energy from the power grid to make up for the power difference between the power source and the sintering fan 4 .

[0063] As a specific example, in a practical embodiment, regarding power matching, considering that when both the induction steam turbine 1 and the ORC turbine 7 are shut down, the dual-purpose motor 3 must be able to bring the sintering fan 4 to rated load, the motor power of the dual-purpose motor 3 is equal to the power of the sintering fan 4. The power of the induction steam turbine 1 and the power of the ORC turbine depend on the utilization of sintering waste heat. The generator power of the dual-purpose motor 3 is equal to the power of the induction steam turbine 1 + the power of the ORC turbine - the power of the sintering fan 4. For example, if the power of the induction steam turbine 1 is 12 MW, the power of the sintering fan 4 is 8 MW, and the power of the ORC turbine is 2 MW, the motor power of the dual-purpose motor 3 is 8 MW, and the generator power of the dual-purpose motor 3 is 6 MW.

[0064] In summary:

[0065] 1. The present invention provides a high-efficiency cascade comprehensive utilization system and method for sintering waste heat. Through the design of the cooler, high-temperature flue gas and low-temperature flue gas are utilized in stages, fully realizing the operation of the steam turbine and the turbine. According to the different temperatures of the flue gas, the thermal energy can be fully utilized.

[0066] 2. The present invention provides a high-efficiency cascaded comprehensive utilization system and method for sintering waste heat. This system combines a steam turbine-driven generator, an ORC turbine-driven generator, and an electric motor into a single device, a dual-purpose motor. This reduces equipment investment and avoids multiple conversions of electrical energy, thus avoiding energy losses from multiple conversions. The ORC system does not need to be equipped with a separate generator and electrical system, thus reducing ORC system investment and improving the return on investment.

[0067] 3. The present invention provides a system and method for the efficient cascade comprehensive utilization of sintering waste heat. The output of the steam turbine and ORC turbine first drives the sintering fan, and the remaining power drives the dual-purpose motor to generate electricity. Compared with generating electricity using the full power of the steam turbine and ORC turbine, the generated power is smaller, the investment in power transmission and transformation equipment will be reduced, and the project construction cost will be saved. The thermal power station, sintering fan station, and ORC plant are integrated, saving the project civil construction cost, while optimizing the operating personnel configuration and reducing the number of operation and maintenance personnel. Compared with traditional steam traction, the dual-purpose motor in this system can be instantly converted into an electric motor, which continues to drive the sintering fan under steam turbine accident conditions, thereby improving the stability of the sintering fan operation.

[0068] The present invention is not limited to the aforementioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A high-efficiency cascade comprehensive utilization system for sintering waste heat, characterized by: The cooling machine comprises a cooling machine for high-temperature mineral cooling, wherein the cooling machine has two flue gas ducts, including a high-temperature flue gas duct and a low-temperature flue gas duct, wherein the high-temperature flue gas duct with a higher temperature is connected to the steam turbine heat system, and the other low-temperature flue gas duct with a lower temperature is connected to the ORC turbine heat system; The flue gas discharged from the high-temperature flue gas pipeline with a higher temperature is used to heat water and generate steam for use in the steam turbine heat system to perform work; The flue gas discharged from the low-temperature flue gas pipeline with a lower temperature is used to heat the working medium, and the heat energy of the working medium is used to generate work in the ORC turbine heat system; An energy dissipation device is provided between the steam turbine heat system and the ORC turbine heat system; The energy consumption device includes a coaxially arranged dual-purpose motor and a sintering fan, which are connected to the steam turbine heat system and the ORC turbine heat system at both ends through a steam turbine speed change clutch and an ORC turbine speed change clutch respectively; The steam turbine heat system includes a steam-assisted steam turbine connected to a steam turbine speed-changing clutch. The steam inlet of the steam-assisted steam turbine is derived from a waste heat boiler. The heat of the waste heat boiler is derived from a cooler. The heat of the flue gas is utilized and discharged. The exhaust steam of the steam-assisted steam turbine is connected to a condenser. The condensed water generated by the condenser is transported to the waste heat boiler. A feed water pump for increasing the pressure of the condensed water is also provided on the pipeline connecting the condenser and the waste heat boiler. The ORC turbine heat system includes an ORC turbine connected to an ORC turbine speed change clutch. The heat source of the ORC turbine is derived from an ORC boiler. The heat source of the ORC boiler is derived from a low-temperature flue gas pipe. The flue gas enters the ORC boiler through the low-temperature flue gas pipe and is then discharged through a chimney. After heat exchange in the ORC boiler, the working fluid enters the ORC turbine to perform work. After performing work, it is discharged into the ORC condenser and then enters the ORC boiler through the ORC condenser. An ORC working fluid pump is also provided on the pipeline connecting the ORC condenser and the ORC boiler. The exhaust end of the waste heat boiler for exhausting flue gas is connected to the low-temperature flue gas pipeline and is mixed with the low-temperature flue gas in the low-temperature flue gas pipeline.

2. The high-efficiency cascade comprehensive utilization system for sintering waste heat according to claim 1, characterized in that: The waste heat boiler is a dual-pressure waste heat boiler, which has two steam outlet ports. The steam with a relatively high temperature enters the steam supply turbine through the medium-pressure steam inlet pipe, and the steam with a relatively low temperature is connected to the middle part of the steam supply turbine through the low-pressure steam supply pipe.

3. A method for efficient cascade comprehensive utilization of sintering waste heat, using a system for efficient cascade comprehensive utilization of sintering waste heat according to any one of claims 1 to 2, characterized in that: The following steps are involved: The high-temperature mineral is cooled in the cooler, and high-temperature flue gas and low-temperature flue gas are generated at different locations. The high-temperature flue gas enters the waste heat boiler along its high-temperature flue gas pipe, where it fully exchanges heat with water vapor. After the heat exchange, the low-temperature flue gas is discharged from the boiler along the low-temperature flue gas pipe; The low-temperature flue gas from the exhaust of the waste heat boiler is mixed with the low-temperature flue gas from the cooler. The mixed low-temperature flue gas enters the ORC boiler, where it fully exchanges heat with the working medium. Finally, the exhaust gas is discharged from the ORC boiler and discharged into the atmosphere through the chimney. In terms of the steam cycle, medium-pressure steam from the waste heat boiler enters the supplementary steam turbine along the medium-pressure steam inlet pipe, driving the supplementary steam turbine to rotate and generate power. At the same time, low-pressure steam from the waste heat boiler enters the middle part of the supplementary steam turbine along the low-pressure supplementary steam pipe, feeding the turbine to generate power. The turbine's speed-changing clutch drives the dual-purpose motor and the rotating shaft of the sintering fan. After completing energy conversion in the turbine, the steam is discharged into the condenser along the exhaust pipe, condensed into water in the condenser, and re-enters the waste heat boiler through the feedwater pump and pipeline, completing the entire steam cycle. In terms of working fluid circulation, the working fluid absorbs heat in the ORC boiler, increases its parameters, and enters the ORC turbine along the working fluid inlet pipe. The working fluid expands and performs work in the ORC turbine, driving the ORC turbine to rotate and output power. The ORC turbine speed clutch drives the rotating shaft of the dual-purpose motor and the sintering fan. The working fluid that has completed energy conversion enters the ORC condenser, condenses into liquid, and is then pumped into the ORC boiler through the ORC working fluid pump, completing the entire organic working fluid cycle.

4. The method for efficient cascade comprehensive utilization of sintering waste heat according to claim 3, characterized in that: When the supplemental steam turbine fails to start or fails, the turbine speed change clutch disengages, and the supplemental steam turbine is isolated from the entire shafting system. At this time, the sintering fan, dual-purpose motor, and ORC turbine achieve power balance. When the ORC turbine fails to start or fails, the ORC turbine speed change clutch disengages, and the ORC turbine is isolated from the entire shaft system. At this time, the steam injection turbine, dual-purpose motor, and sintering fan achieve power balance; When all equipment is operating normally, both clutches are engaged, and the steam turbine, ORC turbine, dual-purpose motor, and sintering fan achieve power balance.

5. The method for efficient cascade comprehensive utilization of sintering waste heat according to claim 4, characterized in that: When the output power of the ORC turbine and / or the air-injection steam turbine is greater than the power of the sintering fan, the dual-purpose motor acts as a generator and the electric energy is input into the grid; When the output power of the ORC turbine and / or the air-supplemented steam turbine is less than that of the sintering fan, the dual-purpose motor acts as an electric motor and absorbs electric energy from the power grid to make up for the power difference between the power source and the sintering fan.

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