Comprehensive recycling system and method for low-temperature waste heat of iron and steel enterprises

Abstract

The invention provides a comprehensive recycling system and method for low-temperature waste heat of an iron and steel enterprise. The system comprises a blast furnace slag flushing water tank, a heat exchanger and a heat exchanger, wherein blast furnace slag flushing water is stored in the blast furnace slag flushing water tank; the heat exchanger comprises a blast furnace slag flushing water heat exchanger and a flue heat exchanger, the blast furnace slag flushing water heat exchanger is communicated with the blast furnace slag flushing water tank, and the flue heat exchanger is arranged in a flue of the sintering system; the preheater is arranged between the blast furnace slag flushing water heat exchanger and the turbine, and the blast furnace slag flushing water heat exchanger preheats the circulating working medium through the replaced heat; the evaporator is arranged between the preheater and the turbine for communication, and is used for heating the preheated circulating working medium to a superheated steam state; a circulating working medium is arranged in the turbine, the turbine is communicated with the preheater, the evaporator and the flue heat exchanger, the evaporator heats the circulating working medium to be in a superheated steam state through the replaced heat, the flue heat exchanger heats the circulating working medium to be in a saturated steam state through the replaced heat, and the turbine converts heat energy into mechanical energy to drive a load system to use.

Description

Technical Field

[0001] This application relates to the field of waste heat utilization technology of sintering machine flue gas, specifically to a comprehensive low-temperature waste heat recovery and utilization system and method for steel enterprises. Background Technology

[0002] In the steel industry, the utilization of waste heat from the blast furnace process in sintering machines is a key aspect of achieving energy conservation and carbon reduction. Currently, the medium-temperature flue gas (above 350°C) generated by the sintering machine and the medium-temperature flue gas from the first (approximately 400°C) and second (approximately 300°C) stages of the sintering annular cooler have been largely recovered and utilized, typically generating steam through waste heat boilers for further power generation or heating. However, waste heat resources such as blast furnace slag flushing water (approximately 75°C), sintering machine tail gas (approximately 180°C), annular cooler chute gas (approximately 230°C), and the third and fourth stage flue gas from the annular cooler (approximately 250°C) are difficult to recover and utilize independently due to their lower temperatures and grades, and still require further efficient development and integrated utilization.

[0003] After solid-liquid separation, the blast furnace flushing water is introduced into a special plate heat exchanger to exchange heat with circulating water. The heated circulating water (which can be heated to 60-70℃) is then transported to the plant's office buildings, workshops, or surrounding communities for winter heating, or used as a heat source for refrigeration equipment in summer. The flue gas from the third and fourth stages of the sintering process is generally sent to the sintering trolley for hot blast sintering; some companies also use it as a heat source for Organic Rankine Cycle (ORC) power generation systems. However, only a very small number of companies use the exhaust gas from the sintering machine and the waste heat from the sintering ring cooler chute to generate low-temperature steam for sintering and material distribution. Most companies still treat it by simply releasing it after dust removal, indicating that there is still considerable room for improvement in energy conservation and emission reduction in steel enterprises.

[0004] Currently, most steel companies still limit the utilization of the aforementioned low-temperature waste heat to a single-point, decentralized recovery model. This model has many limitations in practical applications: the utilization of waste heat from blast furnace slag flushing water is significantly constrained by seasonality, resulting in a low utilization rate; although the waste heat can drive ORC power generation systems, the power generation is low due to the low flue gas temperature and limited conversion efficiency of organic working fluids, making it difficult to improve the return on investment; in addition, the application rate of waste heat recovery from sintering machine tail flue gas and annular cooler chute flue gas is still low in the industry, and a mature and efficient large-scale utilization path has not yet been formed.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] This application provides a low-temperature waste heat comprehensive recovery and utilization system for steel enterprises, which mainly aims to solve the many limitations of waste heat utilization in the sintering system in the existing technology: the waste heat of blast furnace slag water is significantly affected by seasonality, the power generation is low, and the return on investment is difficult to improve.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention provides a low-temperature waste heat comprehensive recovery and utilization system for steel enterprises, installed on a sintering system, comprising:

[0009] Blast furnace slag flushing water pool: It contains blast furnace slag flushing water;

[0010] The heat exchanger includes a blast furnace slag flushing water heat exchanger and a flue heat exchanger. The blast furnace slag flushing water heat exchanger is connected to the blast furnace slag flushing water pool, and the flue heat exchanger is installed in the flue of the sintering system.

[0011] Preheater: Located between the blast furnace slag flushing water heat exchanger and the turbine, the blast furnace slag flushing water heat exchanger preheats the circulating working fluid with the heat dissipated.

[0012] Evaporator: Located between the preheater and the turbine, used to heat the preheated circulating working fluid to a superheated steam state;

[0013] Turbine: Internally equipped with a circulating working fluid, connected to the preheater, the evaporator, and the flue heat exchanger. The evaporator uses the displaced heat to heat the circulating working fluid to a superheated steam state, and the flue heat exchanger uses the displaced heat to heat the circulating working fluid to a saturated steam state. The turbine converts thermal energy into mechanical energy to drive the load system.

[0014] This invention utilizes the flue gas and blast furnace slag flushing water of the sintering system by setting up a heat exchanger, which greatly improves the waste heat utilization rate of the sintering system.

[0015] In one specific implementation, the flue heat exchanger includes a tail flue heat exchanger and a chute flue heat exchanger;

[0016] The sintering system includes a tail dust removal flue and a chute dust removal flue. The tail flue heat exchanger is installed in the tail dust removal flue, and the chute flue heat exchanger is installed in the chute dust removal flue.

[0017] The tail flue heat exchanger and the chute flue heat exchanger are equipped with soot blowing components.

[0018] In one specific implementation, the soot blowing assembly includes an air filter, an air compressor, a control valve, a compressed air tank, a pulse valve, a blowpipe, and a control system;

[0019] The air filter is sequentially connected to the air compressor, the control valve, the compressed air storage tank, the pulse valve, and the blow pipe. The blow pipe performs soot blowing on the tail flue heat exchanger and the chute flue heat exchanger.

[0020] The control system is connected to the air filter, the air compressor, the control valve, the compressed air tank, the pulse valve, and the blowpipe to control the soot blowing operation.

[0021] In one specific implementation, the sintering system includes a fume hood, and the evaporator is connected to the fume hood and exchanges heat with the flue gas inside the fume hood.

[0022] In one specific implementation scheme, the preheating temperature is 60-70°C;

[0023] The temperature of the circulating working fluid in the superheated steam state is 170-180℃, and the pressure is 0.5MPa.a.

[0024] The pressure of the circulating working fluid in the saturated steam state is 0.5 MPa.a.

[0025] In one specific implementation, the load system includes an electric generator and an annular cooling fan;

[0026] The turbine, the electric generator, and the annular cooling fan are arranged coaxially via a speed-changing clutch.

[0027] This invention also provides a method for the comprehensive recovery and utilization of low-temperature waste heat applicable to the aforementioned comprehensive low-temperature waste heat recovery and utilization system for steel enterprises, which includes the following steps:

[0028] The blast furnace slag water preheats the circulating working fluid through the blast furnace flushing water heat exchanger;

[0029] The flue gas in the sintering system's flue gas evaporator heats the preheated circulating working fluid to a superheated steam state. The superheated steam state circulating working fluid enters the turbine to do work, converting thermal energy into mechanical energy, which drives the load system to do work.

[0030] The flue gas in the sintering system heats the circulating working fluid to a saturated steam state through the flue heat exchanger. The saturated steam state circulating working fluid enters the turbine to do work, converting thermal energy into mechanical energy, which drives the load system to do work.

[0031] In one specific implementation scheme, the turbine performs work by including the following steps:

[0032] When the steam pressure of the circulating working fluid heated by the tail flue heat exchanger and the chute flue heat exchanger is greater than the steam pressure of the evaporator, the circulating working fluid in the saturated steam state heated by the tail flue heat exchanger and the chute flue heat exchanger is the main steam, and the evaporator is the auxiliary steam, which is sent to the turbine to do work.

[0033] When the steam pressure of the circulating working fluid heated by the tail flue heat exchanger and the chute flue heat exchanger is equal to the steam pressure of the evaporator, the three circulating working fluids are mixed and fed into the turbine together.

[0034] In one specific implementation scheme, the process of driving the load system to perform work includes the following steps;

[0035] When the turbine is not started or malfunctions, the electric generator acts as the motor, driving the ring-cooled fan to run;

[0036] When the turbine starts:

[0037] When the output power of the turbine is less than the operating power of the annular cooling fan, the electric generator is an electric motor to make up for the power difference between the turbine and the annular cooling fan;

[0038] When the output power of the turbine is greater than the operating power of the annular cooling fan, the electric motor becomes an electric generator, converting the remaining power output by the turbine into electrical energy to be uploaded to the power grid.

[0039] In a specific feasible implementation, the following steps are also included:

[0040] Ash removal is performed on the tail flue heat exchanger and the chute flue heat exchanger:

[0041] When the automatic operation mode is selected, the control system periodically controls the blowpipe to perform soot blowing according to the preset time interval;

[0042] When the manual operation mode is selected, if the amount of steam of the circulating working medium heated by the tail flue heat exchanger and the chute flue heat exchanger is reduced, the ash accumulation can be confirmed through the observation hole. If it is determined that the reduction in steam is caused by excessive ash accumulation on the surface of the tail flue heat exchanger and the chute flue heat exchanger, the blowpipe can be manually started to perform ash blowing.

[0043] Compared with the prior art, this application has at least the following advantages:

[0044] 1. This innovative approach integrates the waste heat resources from the sintering machine tail dust collector flue and chute dust collector flue, which are rarely used in the steel industry. Combined with the waste heat from blast furnace slag flushing water and the waste heat from the flue gas collected by the fume hood, a low-grade waste heat cascade utilization system is constructed. Through multi-energy complementary energy regulation, the system deeply solves the recovery problem and significantly improves the comprehensive utilization rate of waste heat resources in steel enterprises.

[0045] 2. The system adopts a dual-drive (steam and electric) mode, where the mechanical energy generated by the turbine directly drives the annular cooling fan, avoiding the losses from two conversions ("thermal energy - electrical energy - mechanical energy") and improving system thermal efficiency by approximately 6%. Simultaneously, the electric generator and the annular cooling fan share a single electrical system, eliminating the need for a dedicated generator and related equipment, reducing plant construction costs and maintenance personnel expenses, and simplifying the system structure while lowering investment and operating costs. Attached Figure Description

[0046] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0047] Figure 1 This is a process flow diagram of the low-temperature waste heat comprehensive recovery and utilization system for steel enterprises provided in the embodiments of the present invention;

[0048] Figure 2 This is an installation diagram of the flue heat exchanger provided in an embodiment of the present invention;

[0049] Figure 3 This is an installation diagram of the load system provided in an embodiment of the present invention;

[0050] Figure 4 This is a process flow diagram of the soot blowing assembly provided in an embodiment of the present invention.

[0051] in:

[0052] 1-Blast furnace slag flushing water tank; 2-Slag water filter; 3-Blast furnace slag flushing water heat exchanger; 4-Slag flushing device; 5-Building end; 6-Soft water tank; 7-Preheater; 8-Flue heat exchanger; 81-Sintering machine; 82-Sintering annular cooler chute; 83-Annular cooler; 84-Tail dust removal flue; 85-Tail flue heat exchanger; 86-Chute dust removal flue; 87-Chute flue heat exchanger; 9-Evaporator; 10-Turbine 11-Condenser; 12-Working fluid pump; 13-Working fluid tank; 14-Flue gas treatment device; 15-Fume hood; 16-Load system; 161-Speed ​​change clutch; 162-Electric generator; 163-Circular cooler; 17-Control system; 171-Air filter; 172-Air compressor; 173-Control valve; 174-Compressed air storage tank; 175-Pulse valve; 176-Purge pipe. Detailed Implementation

[0053] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0054] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0055] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed connection, detachable connection, or integral connection; they can refer to mechanical connection or electrical connection; they can refer to direct connection or indirect connection through an intermediate medium; and they can refer to the connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0056] To more clearly illustrate the technical solutions in this invention, specific embodiments are described below.

[0057] Example 1

[0058] like Figure 1-4 As shown, this embodiment provides a system and method for the comprehensive recovery and utilization of low-temperature waste heat in steel enterprises. It is mainly to solve the many limitations of the waste heat utilization in the sintering system in the existing technology, such as the obvious seasonality of blast furnace slag water waste heat, low power generation capacity, and difficulty in improving the return on investment.

[0059] In this embodiment, the low-temperature waste heat recovery and utilization system for steel enterprises provided is applied to the sintering system. It includes a blast furnace slag flushing water pool 1, a heat exchanger, and a turbine 10. The heat exchanger converts the heat of the flue gas in the blast furnace slag flushing water pool 1 and the flue gas in the sintering system into the circulating working fluid in the turbine 10. The circulating working fluid does work in the turbine 10, converting thermal energy into mechanical energy. The turbine 10 drives the load system 16 to do work, increasing the utilization rate of waste heat of the turbine 10 and expanding its application scenarios, thereby increasing the return on investment.

[0060] The blast furnace slag flushing water pool 1 stores blast furnace slag flushing water, which is connected to a slag flushing device 4. The blast furnace slag flushing water pool 1 is also connected to a slag water filter 2 for solid-liquid separation of the blast furnace slag flushing water.

[0061] To facilitate better heat exchange, the heat exchangers include a blast furnace slag flushing water heat exchanger 3 and a flue heat exchanger 8. The blast furnace slag flushing water heat exchanger 3 is connected to the slag water filter 2 and is also connected to a soft water tank 6 and a building end 5. When the blast furnace slag flushing water in the blast furnace slag flushing water pool 1 is filtered by the slag water filter 2, it enters the blast furnace slag flushing water heat exchanger 3 to exchange heat with the soft water. After cooling, the blast furnace slag flushing water passes through the slag flushing device 4 and returns to the blast furnace slag flushing water pool 1 with the high temperature. The soft water is heated by the heat exchanger and then delivered to the building end 5 for users to use for heating or bathing. After the building end 5 is finished using the water, it returns to the soft water tank 5 to complete one cycle.

[0062] This embodiment also provides a preheater 7, which is located between the blast furnace slag flushing water heat exchanger 3 and the turbine 10. Specifically, after the soft water heat exchange, a portion of the soft water carrying heat enters the preheater 7 to preheat the circulating working fluid, wherein the preheating temperature is 60-70℃.

[0063] To increase waste heat utilization efficiency, in this embodiment, the sintering system includes a sintering machine 81 and an annular cooler 83. The annular cooler 83 is connected to the evaporator 9. Specifically, the low-temperature section of the annular cooler's fume hood 15 is connected to the evaporator 9 to exchange heat with the flue gas inside the fume hood 15. The evaporator 9 is located between the fume hood 15 and the turbine 10 to reheat the circulating working fluid preheated by the preheater 7. The evaporator 9 heats the preheated circulating working fluid to a superheated steam state by exchanging heat between the flue gas inside the fume hood 15 and the preheated circulating working fluid. The superheated steam circulating working fluid enters the turbine 10 to perform work, converting heat into mechanical energy, which drives the load system 16 to perform work. The flue gas after heat exchange in the evaporator 9 enters the flue gas treatment device 14 for treatment before being discharged. The temperature of the superheated steam circulating working fluid is 170-180℃, and the pressure is 0.5 MPa.a. The working efficiency of the turbine 10 is improved by adjusting the steam state at the inlet of the turbine 10 through the evaporator 9. The evaporator 9 is a high-efficiency shell-and-tube or plate heat exchanger.

[0064] The flue heat exchanger 8 is used to utilize the heat of the flue gas in the flue of the sintering machine 81. The flue heat exchanger 8 includes a tail flue heat exchanger 85 and a chute flue heat exchanger 87. The sintering machine 81 includes a tail dust removal flue 84 and a chute dust removal flue 86. The chute dust removal flue 86 is located at the upper end of the sintering ring cooler chute 82 between the ring cooler 83 and the sintering machine 81. The tail dust removal flue 84 is located at the tail of the sintering machine 81. The tail flue heat exchanger 85 is installed in the tail dust removal flue 84, and the chute flue heat exchanger 87 is installed in the chute dust removal flue 86, so as to exchange heat with the flue gas in the tail dust removal flue 84 and the chute dust removal flue 86 respectively. The tail flue heat exchanger 85 and the chute flue heat exchanger 87 are connected to the turbine 10, exchanging heat between the flue gas in the tail dust removal flue 84 and the chute dust removal flue 86 and the circulating working fluid. This heats the circulating working fluid to a saturated steam state. The saturated steam circulating working fluid then enters the turbine 10 to perform work, converting heat into mechanical energy, which drives the load system 16 to perform work. The pressure of the circulating working fluid in the saturated steam state is 0.5 MPa.

[0065] Meanwhile, in order to ensure that the heat exchange efficiency of the tail flue heat exchanger 85 and the chute flue heat exchanger 87 is not affected, a soot blowing assembly is also provided in this embodiment to perform soot blowing on the tail flue heat exchanger 85 and the chute flue heat exchanger 87. The soot blowing assembly includes an air filter 171, an air compressor 172, a control valve 173, a compressed air tank 174, a pulse valve 175, a blowpipe 176, and a control system 17. The air filter 171 is connected in sequence to the air compressor 172, the control valve 173, the compressed air tank 174, the pulse valve 175, and the blowpipe 176. The blowpipe 176 performs soot blowing on the tail flue heat exchanger 85 and the chute flue heat exchanger 87.

[0066] The control system 17 is connected to the air filter 171, air compressor 172, control valve 173, compressed air tank 174, pulse valve 175, and blow pipe 176 to control the soot blowing operation.

[0067] In this embodiment, the load system 16 includes an electric generator 162 and an annular cooling fan 163, wherein the turbine 10 is coaxially arranged with the electric generator 162 and the annular cooling fan 163 via a speed-changing clutch 161.

[0068] Of course, it should be noted that in this embodiment, the preheater 7, evaporator 9, turbine 10, tail flue heat exchanger 85 and chute flue heat exchanger 87 are connected by steam pipes.

[0069] Of course, after the working fluid finishes doing work in the turbine 10, it comes out of the turbine 10 outlet and enters the condenser 11 through the steam pipe. The condensed working fluid enters the working fluid tank 13 through the working fluid pump 12 for storage, thus completing the cycle.

[0070] To further enhance understanding of this application, this application also provides a method for comprehensive recovery and utilization of low-temperature waste heat, which is compatible with the aforementioned comprehensive recovery and utilization system for low-temperature waste heat in steel enterprises. This method includes the following steps:

[0071] 1. The blast furnace slag flushing water at 70℃~85℃ in the blast furnace slag flushing water pool 1 is filtered by the slag water filter 2 and then exchanged with soft water in the blast furnace slag flushing water heat exchanger 3. The soft water after heat exchange enters the building end 5 for users to use for heating or bathing. After heat exchange, the blast furnace slag flushing water returns to the blast furnace slag flushing water pool 1 through the slag flushing device 4 for recycling.

[0072] Meanwhile, some of the soft water carrying heat enters the preheater 7 and exchanges heat with the circulating working fluid, preheating the circulating working fluid to 60-70℃.

[0073] 2. The flue gas in the fume hood 15 is heat exchanged. The flue gas in the fume hood 15 enters the evaporator 9 and exchanges heat with the preheated circulating working fluid. The preheated circulating working fluid is heated to a superheated steam state. The superheated steam state circulating working fluid enters the turbine 10 to do work, converting heat into mechanical energy, and driving the load system 16 to do work.

[0074] 3. The tail flue heat exchanger 85 and the chute heat exchanger 87 in the tail dust removal flue 84 and the chute dust removal flue 86 of the sintering machine 81 respectively exchange heat with the flue gas in the tail dust removal flue 84 and the chute dust removal flue 86. Through the tail flue heat exchanger 85 and the chute heat exchanger 87, the flue gas in the tail dust removal flue 84 and the chute dust removal flue 86 exchanges heat with the circulating working medium, heating the circulating working medium to a saturated steam state. The saturated steam state circulating working medium enters the turbine 10 to do work, converting heat into mechanical energy, and driving the load system 16 to do work.

[0075] The process of introducing the circulating working fluid in saturated steam state and the circulating working fluid in superheated steam state into the turbine 10 includes the following steps:

[0076] When the steam pressure of the circulating working medium heated by the tail flue heat exchanger 85 and the chute flue heat exchanger 87 is greater than the steam pressure of the evaporator 9, the circulating working medium in saturated steam state heated by the tail flue heat exchanger 85 and the chute flue heat exchanger 87 is the main steam, and the evaporator 9 is the auxiliary steam, which is sent to the turbine 10 to do work.

[0077] When the steam pressure of the circulating working fluid heated by the tail flue heat exchanger 85 and the chute flue heat exchanger 87 is equal to the steam pressure of the evaporator 9, the three circulating working fluids are mixed in the steam pipe and then enter the turbine 10 to do work.

[0078] 4. The turbine 10 drives the load system 16 to perform work, including:

[0079] When the turbine 10 is not started or malfunctions, the electric generator 162 acts as a motor to drive the ring-cooled fan 163.

[0080] When turbine 10 starts:

[0081] When the output power of turbine 10 is less than the operating power of ring cooler 163, electric generator 162 acts as a motor to make up for the power difference between turbine 10 and ring cooler 163.

[0082] When the output power of turbine 10 is greater than the operating power of the ring cooler 163, the motor becomes an electric generator 162, which converts the excess power output by turbine 10 into electrical energy to be uploaded to the power grid.

[0083] 5. Perform ash removal work on the tail flue heat exchanger 85 and the chute flue heat exchanger 87:

[0084] When the automatic operation mode is selected, the control system 17 periodically controls the blowpipe 176 to perform soot blowing work according to the preset time interval.

[0085] When the manual operation mode is selected, if the amount of steam of the circulating working medium heated by the tail flue heat exchanger 85 and the chute flue heat exchanger 87 is reduced, the ash accumulation can be confirmed through the observation hole. If it is determined that the reduction in steam is caused by excessive ash accumulation on the surface of the tail flue heat exchanger 85 and the chute flue heat exchanger 87, the blowpipe 176 is manually started to perform soot blowing.

[0086] The beneficial effects of this application are as follows:

[0087] 1. This innovative system integrates the waste heat resources from the tail-end dust removal flue duct 84 of the sintering machine 81 and the dust removal flue duct 86 of the chute, which are rarely used in the steel industry. Combined with the waste heat from the blast furnace slag flushing water and the waste heat from the flue gas in the fume hood 15, a low-grade waste heat cascade utilization system is constructed. Through multi-energy complementary energy regulation, the system deeply solves the recovery problem and significantly improves the comprehensive utilization rate of waste heat resources in steel enterprises.

[0088] 2. Adopting a dual-drive (steam and electric) mode, the mechanical energy generated by the turbine 10 directly drives the annular cooling fan 163, avoiding the losses from two conversions ("thermal energy - electrical energy - mechanical energy"), thus improving system thermal efficiency by approximately 6%. Simultaneously, the electric generator 162 shares an electrical system with the annular cooling fan 163, eliminating the need for a dedicated generator and related equipment, reducing plant construction costs and maintenance personnel costs, and simplifying the system structure while lowering investment and operating costs.

[0089] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. This application is not limited to the exact structures described above and illustrated in the accompanying drawings, and it should not be considered that the specific implementation of this application is limited to these descriptions. For those skilled in the art, various changes and modifications made without departing from the concept of this application should be considered to fall within the protection scope of this application.

Claims

1. A comprehensive low-temperature waste heat recovery and utilization system for steel enterprises, installed on a sintering system, characterized in that, include: Blast furnace slag flushing water pool: It contains blast furnace slag flushing water; The heat exchanger includes a blast furnace slag flushing water heat exchanger and a flue heat exchanger. The blast furnace slag flushing water heat exchanger is connected to the blast furnace slag flushing water pool, and the flue heat exchanger is installed in the flue of the sintering system. Preheater: Located between the blast furnace slag flushing water heat exchanger and the turbine, the blast furnace slag flushing water heat exchanger preheats the circulating working fluid with the heat dissipated. Evaporator: Located between the preheater and the turbine, used to heat the preheated circulating working fluid to a superheated steam state; Turbine: It is equipped with a circulating working fluid, which is connected to the preheater, the evaporator and the flue heat exchanger. The evaporator uses the displaced heat to heat the circulating working fluid to a superheated steam state, and the flue heat exchanger uses the displaced heat to heat the circulating working fluid to a saturated steam state. The turbine converts thermal energy into mechanical energy to drive the load system.

2. The low-temperature waste heat comprehensive recovery and utilization system for steel enterprises according to claim 1, characterized in that, The flue heat exchanger includes a tail flue heat exchanger and a chute flue heat exchanger. The sintering system includes a tail dust removal flue and a chute dust removal flue. The tail flue heat exchanger is installed in the tail dust removal flue, and the chute flue heat exchanger is installed in the chute dust removal flue. The tail flue heat exchanger and the chute flue heat exchanger are equipped with soot blowing components.

3. The low-temperature waste heat comprehensive recovery and utilization system for steel enterprises according to claim 2, characterized in that, The soot blowing assembly includes an air filter, an air compressor, a control valve, a compressed air tank, a pulse valve, a blowpipe, and a control system; The air filter is sequentially connected to the air compressor, the control valve, the compressed air storage tank, the pulse valve, and the blow pipe. The blow pipe performs soot blowing on the tail flue heat exchanger and the chute flue heat exchanger. The control system is connected to the air filter, the air compressor, the control valve, the compressed air tank, the pulse valve, and the blowpipe to control the soot blowing operation.

4. The low-temperature waste heat comprehensive recovery and utilization system for steel enterprises according to claim 1, characterized in that, The sintering system includes a fume hood, and the evaporator is connected to the fume hood and exchanges heat with the flue gas inside the fume hood.

5. The low-temperature waste heat comprehensive recovery and utilization system for steel enterprises according to claim 4, characterized in that, The preheating temperature is 60-70℃; The temperature of the circulating working fluid in the superheated steam state is 170-180℃, and the pressure is 0.5MPa.a. The pressure of the circulating working fluid in the saturated steam state is 0.5 MPa.a.

6. The low-temperature waste heat comprehensive recovery and utilization system for steel enterprises according to claim 1, characterized in that, The load system includes an electric generator and an annular cooling fan; The turbine, the electric generator, and the annular cooling fan are arranged coaxially via a speed-changing clutch.

7. The method for comprehensive recovery and utilization of low-temperature waste heat applicable to the low-temperature waste heat comprehensive recovery and utilization system for steel enterprises according to any one of claims 1-6, characterized in that, Includes the following steps: The blast furnace slag water is preheated by the blast furnace flushing water heat exchanger and preheater to preheat the circulating working fluid. The flue gas in the sintering system's flue gas evaporator heats the preheated circulating working fluid to a superheated steam state. The superheated steam state circulating working fluid enters the turbine to do work, converting thermal energy into mechanical energy, which drives the load system to do work. The flue gas in the sintering system heats the circulating working fluid to a saturated steam state through the flue heat exchanger. The saturated steam state circulating working fluid enters the turbine to do work, converting thermal energy into mechanical energy, which drives the load system to do work.

8. The method for comprehensive recovery and utilization of low-temperature waste heat according to claim 7, characterized in that, The turbine performs work through the following steps: When the steam pressure of the circulating working fluid heated by the tail flue heat exchanger and the chute flue heat exchanger is greater than the steam pressure of the evaporator, the circulating working fluid in the saturated steam state heated by the tail flue heat exchanger and the chute flue heat exchanger is the main steam, and the evaporator is the auxiliary steam, which is sent to the turbine to do work. When the steam pressure of the circulating working fluid heated by the tail flue heat exchanger and the chute flue heat exchanger is equal to the steam pressure of the evaporator, the three circulating working fluids are mixed and fed into the turbine together.

9. The method for comprehensive recovery and utilization of low-temperature waste heat according to claim 7, characterized in that, The process of driving the load system to perform work includes the following steps; When the turbine is not started or malfunctions, the electric generator acts as the motor, driving the ring-cooled fan to run; When the turbine starts: When the output power of the turbine is less than the operating power of the annular cooling fan, the electric generator is an electric motor to make up for the power difference between the turbine and the annular cooling fan; When the output power of the turbine is greater than the operating power of the annular cooling fan, the electric motor becomes an electric generator, converting the remaining power output by the turbine into electrical energy to be uploaded to the power grid.

10. The method for comprehensive recovery and utilization of low-temperature waste heat according to claim 8, characterized in that, It also includes the following steps: Ash removal is performed on the tail flue heat exchanger and the chute flue heat exchanger: When the automatic operation mode is selected, the control system periodically controls the blowpipe to perform soot blowing according to the preset time interval; When the manual operation mode is selected, if the amount of steam of the circulating working medium heated by the tail flue heat exchanger and the chute flue heat exchanger is reduced, the ash accumulation can be confirmed through the observation hole. If it is determined that the reduction in steam is caused by excessive ash accumulation on the surface of the tail flue heat exchanger and the chute flue heat exchanger, the blowpipe can be manually started to perform ash blowing.

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