A method and system for improving the efficiency of a steam turbine

Abstract

This invention proposes a method and system for improving the power generation efficiency of steam turbines, relating to the field of gas-fired power generation technology in steel plants. The method includes: obtaining and purifying high-temperature flushing water from the blast furnace flushing process; using the purified high-temperature flushing water to heat a circulating medium; introducing the heated circulating medium into a thermal storage station to mitigate the intermittency and fluctuations of the waste heat from the flushing water; using the heated circulating medium from the thermal storage station to heat condensate; the cooled circulating medium after heat exchange entering a cold storage station; exchanging heat between the cooled circulating medium from the cold storage station and the purified high-temperature flushing water to form a closed-loop circulation of the circulating medium; and sending the heated condensate, after further multi-stage heating, into a boiler to generate steam to drive the steam turbine for power generation. The method and system proposed in this invention can effectively utilize the waste heat from the blast furnace flushing water, thereby improving overall efficiency.

Description

Technical Field

[0001] This invention relates to the field of gas power generation technology in steel plants, and particularly to a method and system for improving the power generation efficiency of steam turbines. Background Technology

[0002] In steel plant gas-fired power generation systems, a regenerative steam extraction method is commonly used. This method extracts a portion of the steam from the intermediate and low-pressure cylinders of the turbine to heat the condensate collected in the condenser. While this method increases the temperature of the condensate entering the boiler, it results in a loss of power output from that steam. Therefore, the key to improving the overall efficiency of steel plant gas-fired power generation systems lies in finding a way to both increase the temperature of the condensate entering the boiler and reduce the amount of regenerative steam extracted from the intermediate and low-pressure cylinders, thereby enhancing the steam's work-capacity.

[0003] The blast furnace slag flushing process generates a significant amount of waste heat, which is typically carried away by the flushing water and released into the environment, resulting in energy waste and increased environmental pollution. The cold water used for blast furnace slag flushing is usually at a temperature of 30-40°C. After heat exchange with the molten blast furnace slag, the flushing water temperature can rise to 80-90°C, requiring cooling in a cooling tower before recirculation. The large volume of high-temperature flushing water results in a substantial amount of waste heat, which has high heat recovery value. If this waste heat can be recovered and utilized to heat the condensate in the condenser of a gas-fired power generation system, the amount of regenerative steam extracted from the turbine unit can be reduced. This would improve both the utilization rate of waste heat resources and the overall efficiency of the gas-fired power generation system.

[0004] However, the poor quality, high alkalinity, and tendency to scale and corrode of blast furnace flushing water lead to scale buildup and blockage in heat exchangers, reduced heat transfer efficiency, unstable system operation, and easy damage to heat exchangers. This results in leaks of dirty flushing water, contaminating other equipment and media. Furthermore, the intermittent and fluctuating release of waste heat from the high-temperature flushing water makes it difficult to meet the continuous and stable heating demands of condensate heating in gas-fired power generation systems. These factors make it unsuitable to use the high-temperature flushing water from blast furnaces for direct heating of condensate from the condensers in steam turbine generator sets.

[0005] For example, as described in patent CN218093174U, after blast furnace slag flushing is completed, the high-temperature slag flushing water is recycled for waste heat recovery through a vortex tube plate heat exchanger and a secondary heat exchanger to raise the temperature of the condensate. After the condensate is heated, it enters the heater for heating, which can reduce the workload of the heater and the power consumption, and improve the circulation efficiency of the condensate. However, the technology in CN218093174U has obvious defects, namely, the temperature of the blast furnace slag flushing water fluctuates greatly and the impurity content is high, which easily leads to scaling and blockage of the heat exchanger, affecting the stability and continuity of waste heat recovery. Moreover, the quality of the waste heat from the slag flushing water is constrained by the production rhythm of the slag flushing process, making it difficult to achieve continuous and stable heating, which affects the heating effect of the condensate and makes it difficult to improve the overall energy efficiency of the system. Most importantly, the fluctuating waste heat supply will lead to unstable water temperature entering the boiler, affecting boiler load regulation, resulting in fluctuations in steam temperature and pressure, and a decline in steam quality, which seriously affects the safety and stability of the turbine unit operation.

[0006] According to patent CN103937918B, high-temperature slag is water-quenched, and the temperature of the blast furnace flushing water rises as it enters a collection tank or pool, where it exchanges heat with boiler water through a heat exchanger. The flushing water temperature then drops, and the next flushing water heating cycle begins in the blast furnace flushing water circulation system. The boiler water temperature rises and is heated into steam by the boiler in the boiler water vaporization circulation system for user use. The resulting condensate and makeup water are pumped back to the heat exchanger for the next preheating cycle. The technical solution in CN103937918B has significant technical defects. The blast furnace flushing water is complex, with high levels of suspended solids and salts. Over time, it easily forms a fouling layer on the surface of the heat exchanger, leading to decreased heat transfer efficiency and frequent cleaning and maintenance, which affects the system's continuous operation. In severe cases, it can damage the boiler water tubes. If the flushing water enters the boiler water tubes, it may damage the boiler water tubes and turbine blades, causing unit failures, shutdowns, and dangerous accidents. At the same time, the waste heat release process of the flushing water is intermittent and fluctuates, making it difficult to dynamically match with the stable heating demand of condensate, resulting in water temperature fluctuations, reduced energy utilization efficiency, and jeopardization of the power generation system's safety.

[0007] In view of this, based on years of experience in production and design in this and related fields, the inventor proposes a method and system for improving the power generation efficiency of steam turbines, in order to solve the problems existing in the prior art. Summary of the Invention

[0008] The purpose of this invention is to provide a method and system for improving the power generation efficiency of steam turbines, which can effectively improve the overall efficiency of steam turbine power generation.

[0009] To achieve the above objectives, the present invention proposes a method for improving the power generation efficiency of a steam turbine, wherein the method for improving the power generation efficiency of a steam turbine includes: High-temperature flushing water from the blast furnace flushing process is obtained and the high-temperature flushing water is purified. The purified high-temperature slag flushing water is used to heat the circulating medium. The heated heat circulation medium is introduced into the thermal storage station to smooth out the intermittency and fluctuation of the waste heat from the slag flushing water. The condensate is heated using the heat circulation medium from the thermal storage station; The cooled cold circulation medium enters the cold storage station after heat exchange and cooling. The cold circulating medium from the cold storage station exchanges heat with the purified high-temperature slag flushing water to form a closed-loop circulation of the circulating medium. The heated condensate is then heated through multiple stages before being fed into a boiler to generate steam to drive a steam turbine for power generation.

[0010] The present invention also proposes a system for improving the power generation efficiency of a steam turbine, wherein the system for improving the power generation efficiency of a steam turbine includes: A blast furnace unit includes at least a slag flushing treatment device and a slag flushing water purification device. The slag flushing treatment device performs water quenching treatment on the blast furnace molten slag and discharges high-temperature slag flushing water. The slag flushing water purification device purifies the high-temperature slag flushing water. A circulating heat exchange unit includes at least a circulating medium loop forming a closed loop, a first heat exchanger disposed on the circulating medium loop, a heat storage station, a second heat exchanger, and a cold storage station. A circulating medium flows within the circulating medium loop. The first heat exchanger heats the circulating medium with the high-temperature flushing water. The heat storage station stores the circulating medium heated by the high-temperature flushing water, mitigating the intermittency and fluctuations of the waste heat from the high-temperature flushing water. The second heat exchanger uses the heated circulating medium to heat condensate. The cold storage station stores the circulating medium after heat exchange with the condensate. The cold circulating medium exiting the cold storage station re-enters the first heat exchanger to exchange heat with the high-temperature flushing water. The power generation unit includes at least a boiler, a steam turbine, a condenser, and a condensate circuit. The condensate circuit delivers the condensate output from the condenser to the second heat exchanger for heating, and then sends the heated condensate to the boiler. The boiler heats the condensate to generate steam, which drives the steam turbine to generate electricity.

[0011] Compared with the prior art, the present invention has the following features and advantages: The method and system proposed in this invention for improving the power generation efficiency of steam turbines transfer the waste heat from the high-temperature slag flushing water generated in the blast furnace slag flushing process to the condensate in the steam turbine via a circulating medium, reducing the amount of regenerative steam extraction in the steam turbine and thus improving the steam's work capacity. The circulating medium loop and circulating heat exchange unit isolate the blast furnace slag flushing water loop from the condensate loop of the steam turbine unit, preventing damage and pollution from the slag flushing water and ensuring the safe and stable operation of the generator unit. The heat storage station and cold storage station effectively mitigate the intermittency and fluctuation of the high-temperature slag flushing water waste heat in the blast furnace slag flushing process, matching the heating load demand for condensate temperature rise in the steam turbine unit, ensuring the safety and stability of the steam turbine unit's power generation; improving the utilization rate of waste heat and residual heat from the high-temperature slag flushing water in the blast furnace slag flushing process; and improving the overall efficiency of steam turbine power generation. Attached Figure Description

[0012] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, can select various possible shapes and proportions to implement the invention according to specific circumstances.

[0013] Figure 1 This is a flowchart of an embodiment of the method for improving the power generation efficiency of a steam turbine proposed in this invention; Figure 2 This is a schematic diagram of the system for improving the power generation efficiency of steam turbines proposed in this invention.

[0014] Explanation of reference numerals in the attached figures

[0015] 1. Blast furnace; 2. Slag flushing treatment device; 3. Slag flushing water cooling pool; 4. Sedimentation tank; 5. Filter; 6. Slag flushing water hot water pool; 7. First heat exchanger; 8. Thermal storage station; 9. Cold storage station; 10. Second heat exchanger; 11. Primary low-pressure heater; 12. Secondary low-pressure heater; 13. High-pressure heater; 14. Deaerator; 15. Boiler; 16. Superheater; 17. Steam turbine; 18. Generator; 19. Condenser; 20. ... 21. Slag flushing water pump; 22. Cold medium pump; 23. Hot medium pump; 24. Condensate pump; 25. First temperature measuring instrument; 26. Second temperature measuring instrument; 27. Third temperature measuring instrument; 28. Fourth temperature measuring instrument; 29. ​​Fifth temperature measuring instrument; 30. First intelligent regulating valve; 31. Second intelligent regulating valve; 100. Blast furnace unit; 200. Circulating heat storage and exchange unit; 300. Power generation unit; 1000. System. Detailed Implementation

[0016] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, and these should all be considered to fall within the scope of the invention.

[0017] like Figure 1 As shown, this invention proposes a method for improving the power generation efficiency of a steam turbine, which includes: Obtain high-temperature flushing water from the blast furnace flushing process and purify the high-temperature flushing water. The purified high-temperature slag flushing water is used to heat the circulating medium. The heated circulating medium is introduced into the thermal storage station 8 to smooth out the intermittency and fluctuation of the waste heat of the slag flushing water. The condensate is heated using the heat circulation medium from the thermal storage station 8; The cold circulating medium after heat exchange and cooling exchanges heat with the purified high-temperature slag flushing water, forming a closed-loop circulation of the circulating medium. The heated condensate is then heated through multiple stages before being fed into boiler 15 to generate steam that drives turbine 17 to generate electricity.

[0018] The method for improving the power generation efficiency of a steam turbine proposed in this invention utilizes the heat from the recovered high-temperature flushing water to replace part of the regenerated steam extracted from the steam turbine 17 to heat the condensate. The replaced steam can continue to expand and do work in the steam turbine 17, thereby increasing the output power of the steam turbine 17 while consuming the same amount of fuel, directly improving the power generation efficiency and energy utilization rate of the steam turbine, and reducing the energy consumption for power generation.

[0019] The method for improving the power generation efficiency of steam turbines proposed in this invention uses a closed-loop circulation of the circulating medium as a heat exchange medium to completely physically isolate the high-hardness, easily scaled high-temperature flushing water from the condensate of the steam turbine 17. This not only makes full use of the waste heat in the high-temperature flushing water, but also significantly reduces the risk of impurity migration in the high-temperature flushing water, ensuring the safe operation of the steam turbine 17.

[0020] In an optional embodiment of the present invention, the circulating medium is intermediate circulating water.

[0021] In another optional embodiment of the present invention, the circulating medium may also be a refrigerant such as difluoromethane, propane, carbon dioxide or tetrafluoropropylene.

[0022] In an optional embodiment of the present invention, the high-temperature flushing water cools down after exchanging heat with the circulating medium, forming low-temperature flushing water. This low-temperature flushing water is returned and reused in the blast furnace flushing process, forming a closed-loop circulation of flushing water. This significantly reduces fresh water consumption and wastewater discharge, achieving dual recovery of flushing water and heat energy. Simultaneously, it reduces the cooling of the high-temperature flushing water in the cooling tower, thus reducing electricity and water consumption.

[0023] In one optional example of this implementation, the temperature of the low-temperature flushing water formed after cooling is 30~40°C.

[0024] Furthermore, the blast furnace slag at temperatures above 1400°C is heat-exchanged by low-temperature flushing water at 30-40°C to form low-temperature solid blast furnace slag and high-temperature flushing water at around 90°C.

[0025] In an optional embodiment of the present invention, the purification of high-temperature slag flushing water includes sedimentation and filtration, and the filtered high-temperature slag flushing water is stored in a hot water tank 6. Specifically, the high-temperature slag flushing water is precipitated in a sedimentation tank 4, where impurities settle to the bottom, and the high-temperature slag flushing water in the upper or middle part of the sedimentation tank 4 is in a clear state. The clear high-temperature slag flushing water is then filtered by a filter 5 and stored in the hot water tank 6.

[0026] In an optional embodiment of the present invention, the circulating medium is heated by high-temperature flushing water in the first heat exchanger 7. The heated circulating medium then enters the thermal storage station 8, and further heats the condensate in the second heat exchanger 10. After cooling down, the circulating medium returns to the first heat exchanger 7 via the cold storage station 9. The circulating medium forms a closed loop between the first heat exchanger 7, the thermal storage station 8, the second heat exchanger 10, and the cold storage station 9, completely preventing any contact between the high-hardness, high-temperature flushing water and the clean condensate, ensuring the safe operation of the turbine unit. Simultaneously, the pressure, flow rate, and water quality of the circulating medium in the closed loop can be independently controlled, allowing for more flexible adjustment. Adjustments can be made independently based on the conditions of the turbine 17 or the high-temperature flushing water to achieve optimal energy recovery.

[0027] In an optional example of this implementation, the flow rate of the circulating medium entering the second heat exchanger 10 is regulated by the thermal storage station 8, and the flow rate of the circulating medium entering the first heat exchanger 7 is regulated by the cold storage station 9, thereby achieving buffering and distribution of the heat energy carried by the circulating medium. When the supply of high-temperature flushing water is large and the circulating medium recovers a lot of heat, the circulating medium carrying excess heat can be stored in the thermal storage station 8; when the supply of high-temperature flushing water is insufficient or interrupted, the thermal storage station 8 can release the stored circulating medium to continue supplying heat to the second heat exchanger 10. By finely regulating the flow rate of the circulating medium entering the second heat exchanger 10, the heat flow rate and temperature supplied to the condensate can be kept stable, avoiding disturbances to the condensate circulation caused by upstream fluctuations, and ensuring the safe and stable operation of the turbine 17. Similarly, the cold storage station 9 is responsible for regulating the flow rate and temperature of the circulating medium returning to the first heat exchanger 7. By regulating the flow rate and temperature of the circulating medium entering the first heat exchanger 7, the rate and extent of heat acquisition from the high-temperature flushing water can be actively controlled.

[0028] In an optional embodiment of the invention, the temperature of the circulating medium rises to 85°C after being heated by the first heat exchanger 7.

[0029] In one optional embodiment of this implementation, the heated condensate absorbs heat in boiler 15 to form steam. The steam drives turbine 17 to generate electricity and forms exhaust steam. The exhaust steam is then condensed and reheated as condensate, thus forming a closed-loop condensate cycle, i.e., a Rankine cycle. The waste heat recovered from the high-temperature slag flushing water is transferred to the condensate heating stage through the circulating medium. Without changing the condensate circulation structure and operation mode, the enthalpy of the condensate before entering boiler 15 is effectively increased, thereby reducing the steam extraction consumption of turbine 17 or lowering the fuel input of boiler 15.

[0030] In an optional example of this implementation, in the closed-loop circulation of condensate, the condensate undergoes multiple heating processes sequentially, with the high-temperature circulating medium initially heating at least a portion of the condensate. Using the relatively high-temperature circulating medium as a heat source to initially heat the lowest-temperature condensate discharged from condenser 19 fully utilizes the maximum available heat transfer temperature difference between the low-temperature condensate and the circulating medium, resulting in greater thermodynamic efficiency and reduced irreversible heat transfer losses.

[0031] Furthermore, another portion of the condensate undergoes a first heating process via a primary low-pressure heater 11. The condensate heated by the primary low-pressure heater 11 and the condensate heated by the circulating medium converge in a secondary low-pressure heater 12 for a second heating process. After the second heating, the condensate enters a high-pressure heater 13 for a third heating process. This embodiment flexibly allocates the condensate flow direction according to the production rhythm or real-time operating conditions. When there is sufficient waste heat, more condensate can flow through the second heat exchanger 10 to be heated by the circulating medium, maximizing the substitution of low-pressure extraction steam and increasing power generation output. When there is insufficient waste heat or the blast furnace slag flushing process is interrupted, the condensate can be heated entirely by the primary low-pressure heater 11. At the same time, the heat storage station 8 plays a role in smoothing out the intermittency and fluctuation of waste heat, ensuring the continuous and stable heating of the condensate by the circulating medium to the maximum extent, and ensuring that the basic operation of the turbine 17 is not affected.

[0032] The present invention also proposes a system 1000 for improving the power generation efficiency of a steam turbine, the system 1000 comprising: Blast furnace unit 100 includes at least a slag flushing treatment device 2 and a slag flushing water purification device. The slag flushing treatment device 2 performs water quenching treatment on the molten slag of blast furnace 1 and discharges high-temperature slag flushing water. The slag flushing water purification device purifies the high-temperature slag flushing water. The circulating heat storage and exchange unit 200 includes at least a circulating medium loop forming a closed loop, a first heat exchanger 7, a heat storage station 8, a second heat exchanger 10, and a cold storage station 9 disposed on the circulating medium loop. Circulating medium flows within the circulating medium loop. The first heat exchanger 7 heats the circulating medium with high-temperature flushing water. The heat storage station 8 stores the hot circulating medium heated by the high-temperature flushing water, mitigating the intermittency and fluctuation of the residual heat of the high-temperature flushing water. The second heat exchanger 10 uses the heated circulating medium to heat condensate. The cold storage station 9 stores the cold circulating medium after heat exchange with the condensate. The cold circulating medium exiting the cold storage station 9 then re-enters the first heat exchanger 7 to exchange heat with the high-temperature flushing water. The power generation unit 300 includes at least a boiler 15, a steam turbine 17, a condenser 19, and a condensate circuit. The condensate circuit delivers the condensate output from the condenser 19 to the second heat exchanger 10 for heating, and then sends the heated condensate to the boiler 15 after multiple stages of heating. The boiler 15 heats the condensate to generate steam, which drives the steam turbine 17 to generate electricity.

[0033] The system 1000 proposed in this invention for improving the power generation efficiency of steam turbines uses blast furnace slag as a heat source. The heat from the blast furnace slag is safely transferred to the power generation unit 300 through the blast furnace unit 100 and the circulating heat storage and exchange unit 200 to heat the condensate, thereby directly reducing or replacing the steam that would otherwise need to be extracted from the steam turbine 17. This saved steam can continue to expand and perform work in the steam turbine 17, thus effectively improving the output power and power generation efficiency of the steam turbine 17 while maintaining the same fuel input from the boiler 15.

[0034] The system 1000 proposed in this invention for improving the power generation efficiency of steam turbines establishes a reliable physical barrier between the high-temperature flushing water and condensate in the circulating heat storage and exchange unit 200, which is subject to poor water quality. This completely avoids the risk of pollution to the boiler 15 and steam turbine 17 caused by impurities, particles and corrosive components in the high-temperature flushing water. Thus, while recovering waste heat, it ensures the safety and reliability of the long-term operation of the boiler 15 and steam turbine 17.

[0035] In an optional embodiment of the present invention, the first heat exchanger 7 is a fouling-resistant heat exchanger. Each component of the first heat exchanger 7 is made of wear-resistant and corrosion-resistant materials and / or coated with a wear-resistant and corrosion-resistant coating on the surface of each component, thereby effectively resisting the corrosion and wear of the first heat exchanger 7 by high-temperature flushing water and improving the service life of the first heat exchanger 7.

[0036] In an optional embodiment of the present invention, the blast furnace unit 100 further includes a slag flushing water cooling pool 3 and a first slag flushing water pump 20. The slag flushing water cooling pool 3 collects low-temperature slag flushing water that has been cooled by the first heat exchanger 7, and the first slag flushing water pump 20 pumps the low-temperature slag flushing water from the slag flushing water cooling pool 3 into the slag flushing treatment device 2.

[0037] In an optional embodiment of the present invention, the slag flushing water purification device includes, in series: Sedimentation tank 4 is connected to slag flushing treatment device 2 and collects the high-temperature slag flushing water discharged from slag flushing treatment device 2; Filter 5 is connected to sedimentation tank 4 and filters the high-temperature flushing water after sedimentation; The slag flushing water hot water tank 6 is connected to the filter 5 and collects the high-temperature slag flushing water discharged from the filter 5; The second flushing water pump 21 transports the high-temperature flushing water in the flushing water hot water tank 6 to the first heat exchanger 7.

[0038] In an optional embodiment of the present invention, the circulating heat storage and exchange unit 200 further includes: The heat storage station 8 and the heat medium pump 23 are used to collect the circulating medium heated by the first heat exchanger 7. The heat medium pump 23 pumps the circulating medium from the heat storage station 8 into the second heat exchanger 10. The cold storage station 9 and the cold medium pump 22 are used to collect the circulating medium after it has been cooled by the second heat exchanger 10. The cold medium pump 22 pumps the circulating medium from the cold storage station 9 into the first heat exchanger 7.

[0039] With the above structure, the flow rates of the circulating media entering the second heat exchanger 10 and the first heat exchanger 7 are independently controlled by the hot medium pump 23 and the cold medium pump 22, respectively. This allows for precise adjustment of the intensity and timing of heat exchange, enabling proactive adaptation to changes in different operating conditions. This ensures that the heat input to the power generation unit 300 remains stable and controllable, significantly improving the availability and reliability of waste heat recovery. Simultaneously, the thermal storage station 8 can buffer and regulate the waste heat recovered by the circulating medium, effectively balancing the fluctuations in slag flushing waste heat. This solves the problem of intermittent heat release from high-temperature slag flushing water, ensuring a stable output of heat carried by the circulating medium and guaranteeing the continuity and stability of condensate heating.

[0040] In an optional example of this implementation, a heating device is also provided on the circulating medium loop. The heating device is located between the thermal storage station 8 and the thermal medium pump 23 to provide auxiliary heating for the circulating medium in order to improve the heating efficiency of the condensate.

[0041] In one alternative example, the heating device can be a heat pump, an electric heating device, or a flue gas heater.

[0042] In an optional embodiment of the present invention, the power generation unit 300 further includes a component disposed on the condensate circuit: The secondary low-pressure heater 12 heats the condensate after it has been heated by the second heat exchanger 10 for a second time. The high-pressure heater 13 heats the condensate a third time after the second heating.

[0043] In an optional embodiment of this implementation, the power generation unit 300 further includes a primary low-pressure heater 11 connected in parallel with the second heat exchanger 10. A portion of the condensate output from the condenser 19 is first heated by the primary low-pressure heater 11 and then flows into the secondary low-pressure heater 12 for a second heating. With the above structure, if the heat of the circulating medium is insufficient or does not match the heat requirement of the condensate, the primary low-pressure heater 11 supplements the heat to ensure the stability of the condensate temperature.

[0044] In an optional embodiment of the present invention, the power generation unit 300 further includes a deaerator 14 disposed on the condensate circuit, the deaerator 14 being located between the high-pressure heater 13 and the boiler 15.

[0045] In an optional embodiment of the present invention, the power generation unit 300 further includes a condensate pump 24, which is disposed at the condensate outlet of the condenser 19.

[0046] In an optional embodiment of the present invention, the power generation unit 300 further includes a superheater 16 disposed on the condensate circuit, the superheater 16 being located between the boiler 15 and the turbine 17.

[0047] In an optional embodiment of the present invention, the steam turbine 17 drives the generator 18 to generate electricity.

[0048] In an optional embodiment of the present invention, a first temperature measuring instrument 25 is provided between the first slag flushing water pump 20 and the slag flushing treatment device 2, a second temperature measuring instrument 26 is provided between the slag flushing water hot water tank 6 and the second slag flushing water pump 21, a third temperature measuring instrument 27 is provided between the cold storage station 9 and the cold medium pump 22, a fourth temperature measuring instrument 28 is provided between the heat storage station 8 and the heat medium pump 23, and a fifth temperature measuring instrument 29 is provided between the second heat exchanger 10 and the secondary low-pressure heater 12. This allows for real-time monitoring of the temperature parameters at each node, enabling dynamic adjustment of the heat exchange process in conjunction with the production load.

[0049] In an optional embodiment of this implementation, a first intelligent regulating valve 30 is provided between the condenser 19 and the first-stage low-pressure heater 11, and a second intelligent regulating valve 31 is provided between the condenser 19 and the second heat exchanger 10. Through the coordinated linkage of the first intelligent regulating valve 30, the second intelligent regulating valve 31, and multi-point temperature measuring instruments, dynamic optimization and regulation of the condensate heating process can be achieved, improving the system response accuracy and thermal energy utilization efficiency.

[0050] Furthermore, based on real-time production load and temperature feedback signals, the opening degree of the first intelligent regulating valve 30 and the second intelligent regulating valve 31, as well as the flow rates of the first slag flushing water pump 20, the second slag flushing water pump 21, the cold medium pump 22, the hot medium pump 23, and the condensate pump 24 are dynamically adjusted to achieve optimal matching between waste heat utilization and system energy efficiency, ensuring the efficient and stable operation of the entire system under different operating conditions.

[0051] The first intelligent regulating valve 30 and the second intelligent regulating valve 31 can adopt existing technologies and have functions such as status detection and two-way communication.

[0052] In an optional embodiment of the present invention, the system 1000 for improving the power generation efficiency of a steam turbine further includes a control unit (not shown in the figure), wherein a first slag flushing water pump 20, a second slag flushing water pump 21, a cold medium pump 22, a hot medium pump 23, a condensate pump 24, a first temperature measuring instrument 25, a second temperature measuring instrument 26, a third temperature measuring instrument 27, a fourth temperature measuring instrument 28, a fifth temperature measuring instrument 29, a first intelligent regulating valve 30, and a second intelligent regulating valve 31 are respectively electrically or communicatively connected to the control unit.

[0053] Please refer to Figure 1 , Figure 2 The present invention will now be described in detail, with reference to an embodiment, the specific implementation process of the method and system for improving the power generation efficiency of steam turbines proposed in this invention.

[0054] In this embodiment, low-temperature slag flushing water is extracted from the slag flushing water cooling pool 3. The high-temperature slag discharged from the blast furnace 1 is water-quenched in the slag flushing treatment device 2. The heat-absorbing low-temperature slag flushing water becomes high-temperature slag flushing water and is transported via pipeline to the sedimentation tank 4 for solid-liquid separation. The clarified high-temperature slag flushing water enters the filter 5 for further removal of suspended solids. The filtered high-temperature slag flushing water then enters the slag flushing water hot water pool 6. Low-temperature circulating medium in the cold storage station 9 is drawn by the cold medium pump 22 and enters the first heat exchanger 7 to exchange heat with the high-temperature slag flushing water drawn from the slag flushing water hot water pool 6 by the hot medium pump 23. After heat exchange and cooling, the low-temperature slag flushing water enters the slag flushing water cooling pool 3. The temperature of the circulating water increases after heat exchange and is then transported via pipeline to the heat storage station 8 for storage. As needed, the heat transfer pump 23 extracts the high-temperature circulating medium from the thermal storage station 8, exchanges heat with condensate in the second heat exchanger 10, and the cooled circulating medium returns to the cold storage station 9 to continue exchanging heat with the purified high-temperature slag flushing water in the first heat exchanger 7, forming a cycle. The heated condensate sequentially enters the secondary low-pressure heater 12 and the high-pressure heater 13 to absorb heat, is deoxygenated in the deaerator 14, enters the boiler 15 to absorb heat, and after being superheated by the heat exchanger 16, it enters the steam turbine 17 to do work, driving the generator 18 to generate electricity. The exhaust steam is condensed into condensate by the condenser 19 and then sent back to the second heat exchanger 10 by the condensate pump 24, completing the thermodynamic cycle. When the water temperature in the thermal storage station 8 does not meet the requirements, the condensate pumped by the condensate pump 24 can still be sent to the primary low-pressure heater 11 for initial heating through the first intelligent regulating valve 30, and then further heated by the secondary low-pressure heater 12, before entering the heat absorption and power generation cycle. The outlet temperatures of the slag flushing water cooling pool 3, the slag flushing water hot water pool 6, the cold storage station 9, the heat storage station 8, and the outlet temperature of the second heat exchanger 10 are monitored by the first temperature measuring instrument 25, the second temperature measuring instrument 26, the third temperature measuring instrument 27, the fourth temperature measuring instrument 28, and the fifth temperature measuring instrument 29, respectively. The flow rates of condensate entering the second heat exchanger 10 and the primary low-pressure heater 11 are controlled by the first intelligent regulating valve 30 and the second intelligent regulating valve 31, respectively. This allows for dynamic adjustment of the heat exchange process based on real-time monitoring of temperature parameters at each node and in conjunction with production load.

[0055] In this embodiment, the water temperature in the slag flushing water cooling pool 3 is 40°C. After exchanging heat with the blast furnace slag, the temperature of the high-temperature slag flushing water rises to 90°C. After exchanging heat with the circulating medium in the first heat exchanger 7, the temperature of the cooled low-temperature slag flushing water is 40°C. The temperature of the circulating medium in the cold storage station 9 is 35°C. After exchanging heat with the high-temperature slag flushing water, the circulating medium is heated to 85°C and stored in the heat storage station 8. After exchanging heat with the condensate, the circulating medium is cooled to 35°C and stored in the cold storage station 9, and then exchanges heat with the high-temperature slag flushing water again, repeating the cycle. The condensate at 30°C absorbs heat and is heated to 80°C through the second heat exchanger 10, and then enters the secondary low-pressure heater 12 to complete the subsequent heating, vaporization, and power generation cycle, before returning to the condenser 19 to condense.

[0056] The method and system for improving the power generation efficiency of steam turbines proposed in this invention use a circulating medium as the medium. The low-temperature circulating medium undergoes efficient heat exchange with the high-temperature slag flushing water in the first heat exchanger 7, fully recovering its low-grade heat energy. Then, it enters the second heat exchanger 10 through the heat storage station 8 to transfer heat to the condensate, raising its temperature. Simultaneously, the cooled circulating medium returns to the cold storage station 9 and re-enters the first heat exchanger 7 to participate in the next round of heat storage and exchange cycle. The method and system for improving the power generation efficiency of steam turbines proposed in this invention effectively avoids the energy waste caused by the direct discharge of waste heat from slag flushing water in traditional processes. It also reduces the amount of regenerative steam extracted to heat the condensate in the original power generation system 1000, allowing this portion of steam to be used for more efficient power generation, thereby improving the system efficiency of the generator set. The detailed explanations of the above embodiments are intended only to explain the present invention so as to facilitate a better understanding of the present invention. However, these descriptions should not be construed as limiting the present invention for any reason. In particular, the various features described in different embodiments can be arbitrarily combined with each other to form other embodiments. Unless there is an explicit description to the contrary, these features should be understood to be applicable to any embodiment, and not limited to the described embodiments.

Claims

1. A method for improving the power generation efficiency of a steam turbine, characterized in that, The methods for improving the power generation efficiency of steam turbines include: High-temperature flushing water from the blast furnace flushing process is obtained and the high-temperature flushing water is purified. The purified high-temperature slag flushing water is used to heat the circulating medium. The heated heat circulation medium is introduced into the thermal storage station to smooth out the intermittency and fluctuation of the waste heat from the slag flushing water. The condensate is heated using the heat circulation medium from the thermal storage station; The cold circulating medium, after heat exchange and cooling, enters the cold storage station; The cold circulating medium from the cold storage station exchanges heat with the purified high-temperature slag flushing water to form a closed-loop circulation of the circulating medium. The heated condensate is then heated through multiple stages before being fed into a boiler to generate steam to drive a steam turbine for power generation.

2. The method for improving the power generation efficiency of a steam turbine as described in claim 1, characterized in that, The high-temperature slag flushing water exchanges heat with the circulating medium, and its temperature decreases to form low-temperature slag flushing water. The low-temperature slag flushing water is returned and reused in the blast furnace slag flushing process, forming a closed-loop circulation of slag flushing water.

3. The method for improving the power generation efficiency of a steam turbine as described in claim 1, characterized in that, The circulating medium is heated by the high-temperature flushing water in the first heat exchanger, and the heated circulating medium enters the second heat exchanger to heat the condensate. After heat exchange and cooling, the circulating medium returns to the first heat exchanger.

4. The method for improving the power generation efficiency of a steam turbine as described in claim 3, characterized in that, The flow rate of the circulating medium entering the second heat exchanger is regulated by the thermal storage station, and the flow rate of the circulating medium entering the first heat exchanger is regulated by the cold storage station.

5. The method for improving the power generation efficiency of a steam turbine as described in claim 1, characterized in that, The heated condensate absorbs heat in the boiler to form steam, which drives the turbine to generate electricity and forms exhaust steam. The exhaust steam is condensed and then reheated as condensate, forming a closed-loop condensate cycle.

6. The method for improving the power generation efficiency of a steam turbine as described in claim 5, characterized in that, In the closed-loop circulation of the condensate, the condensate undergoes multiple heating processes in sequence, with the high-temperature circulation medium heating at least a portion of the condensate for the first time.

7. The method for improving the power generation efficiency of a steam turbine as described in claim 6, characterized in that, Another portion of the condensate is first heated by a primary low-pressure heater. The condensate heated by the primary low-pressure heater and the condensate heated by the circulating medium flow into a secondary low-pressure heater for a second heating. The condensate after the second heating enters a high-pressure heater for a third heating.

8. A system for improving the power generation efficiency of a steam turbine, characterized in that, The system for improving the power generation efficiency of steam turbines includes: A blast furnace unit includes at least a slag flushing treatment device and a slag flushing water purification device. The slag flushing treatment device performs water quenching treatment on the blast furnace molten slag and discharges high-temperature slag flushing water. The slag flushing water purification device purifies the high-temperature slag flushing water. A circulating heat exchange unit includes at least a circulating medium loop forming a closed loop, a first heat exchanger disposed on the circulating medium loop, a heat storage station, a second heat exchanger, and a cold storage station. A circulating medium flows within the circulating medium loop. The first heat exchanger heats the circulating medium with the high-temperature flushing water. The heat storage station stores the circulating medium heated by the high-temperature flushing water, mitigating the intermittency and fluctuations of the waste heat from the high-temperature flushing water. The second heat exchanger uses the heated circulating medium to heat condensate. The cold storage station stores the circulating medium after heat exchange with the condensate. The cold circulating medium exiting the cold storage station re-enters the first heat exchanger to exchange heat with the high-temperature flushing water. The power generation unit includes at least a boiler, a steam turbine, a condenser, and a condensate circuit. The condensate circuit delivers the condensate output from the condenser to the second heat exchanger for heating, and then sends the heated condensate to the boiler. The boiler heats the condensate to generate steam, which drives the steam turbine to generate electricity.

9. The system for improving the power generation efficiency of a steam turbine as described in claim 8, characterized in that, The blast furnace unit also includes a slag flushing water cooling pool and a first slag flushing water pump. The slag flushing water cooling pool collects low-temperature slag flushing water that has been cooled by the first heat exchanger. The first slag flushing water pump inputs the low-temperature slag flushing water from the slag flushing water cooling pool into the slag flushing treatment device.

10. The system for improving the power generation efficiency of a steam turbine as described in claim 8 or 9, characterized in that, The slag flushing water purification device comprises the following components connected in series: A sedimentation tank is connected to the slag flushing treatment device and collects the high-temperature slag flushing water discharged from the slag flushing treatment device. A filter is connected to the sedimentation tank and filters the high-temperature flushing water after sedimentation. A hot water tank for flushing slag is connected to the filter and collects the high-temperature flushing slag water discharged from the filter; The second flushing water pump delivers the high-temperature flushing water from the flushing water hot water tank to the first heat exchanger.

11. The system for improving the power generation efficiency of a steam turbine as described in claim 10, characterized in that, The circulating heat storage and exchange unit also includes: A thermal storage station and a heat medium pump, wherein the thermal storage station collects the heat circulation medium heated by the first heat exchanger, and the heat medium pump pumps the heat circulation medium into the second heat exchanger; A cold storage station and a cold medium pump are provided. The cold storage station collects the cold circulating medium after it has been cooled by the second heat exchanger, and the cold medium pump pumps the cold circulating medium into the first heat exchanger.

12. The system for improving the power generation efficiency of a steam turbine as described in claim 8, characterized in that, The power generation unit also includes components installed on the condensate circuit: A secondary low-pressure heater is used to reheat the condensate after it has been heated by the second heat exchanger. A high-pressure heater is used to heat the condensate a third time after the second heating.

13. The system for improving the power generation efficiency of a steam turbine as described in claim 12, characterized in that, The power generation unit also includes a primary low-pressure heater connected in parallel with the second heat exchanger. A portion of the condensate output from the condenser is first heated by the primary low-pressure heater and then flows into the secondary low-pressure heater for a second heating.

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