A method for energy saving and carbon reduction of a traditional coal-fired power plant of a self-provided power plant of a steel enterprise

Abstract

The present application belongs to the technical field of energy saving and emission reduction in steel enterprises, and provides a comprehensive utilization and reconstruction method for energy saving and carbon reduction of traditional coal-fired power plants in self-provided power plants of steel enterprises, which realizes co-combustion of pulverized coal and coal gas through upgrading and reconstruction technology of boilers and steam turbines; the method of the present application actively responds to the national policy of "carbon peak and carbon neutralization", realizes the goal of energy saving and emission reduction and energy comprehensive utilization, meets the needs of sustainable development of enterprises, improves the operation efficiency of the unit, realizes coal saving and carbon reduction, effectively guarantees the normal consumption and emergency balance capacity of surplus coal gas of steel enterprises, realizes zero emission of coal gas, and reduces environmental pollution.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and emission reduction technology for steel enterprises, and relates to the comprehensive utilization and transformation of traditional coal-fired power plants in steel enterprises' self-owned power plants for energy conservation and carbon reduction. Specifically, it is a method for energy conservation and carbon reduction transformation of traditional coal-fired power plants in steel enterprises' self-owned power plants. Background Technology

[0002] Thermal power units (especially coal-fired power) are currently the "ballast" of China's power system, facing unprecedented challenges and transformation pressures under the "dual carbon" target. The company's two 300MW coal-fired units were put into operation at the end of 2010 and have been running for over 10 years. Due to long-term operation, equipment aging and performance degradation have occurred, resulting in low unit efficiency and a coal consumption of approximately 318gce / kWh, far exceeding national energy conservation and emission reduction requirements. Furthermore, the company has a large amount of unused surplus coal gas generated during ironmaking, coking, and steelmaking processes. In conclusion, energy-saving and carbon-reduction retrofitting of traditional coal-fired power plants is imperative. Summary of the Invention

[0003] The purpose of this invention is to provide a method for energy conservation and carbon reduction in the transformation of traditional coal-fired power plants in steel enterprises' self-owned power plants, so as to achieve the goals of energy conservation, emission reduction, and comprehensive energy utilization, meet the needs of the enterprise's sustainable development, improve the operating efficiency of the unit, save coal and reduce carbon, effectively ensure the normal consumption and emergency balance of surplus coal gas in steel enterprises, achieve zero coal gas emission, and reduce environmental pollution.

[0004] The technical solution adopted by the present invention to achieve the above objectives is as follows: A method for energy-saving and carbon-reducing retrofitting of traditional coal-fired power plants in steel enterprises' self-owned power plants includes: S1, pulverized coal and coal gas are co-fired, with a co-firing capacity of 150 kNm³. 3 / h blast furnace gas and converter gas mixture and 20kNm 3 / h coke oven gas; after blending with 150kNm3 / h of low-calorific-value gas, it is necessary to ensure that the main steam and reheat steam temperatures can reach the rated values ​​of 571 / 569℃ when the unit is at a load of 75% or higher. The blast furnace gas and converter gas are mixed in a volume ratio of 30:4. After being mixed, the mixture is sent to the furnace front and then sent to the burner for combustion via a gas pipeline. Coke oven gas is transported by a separate pipeline.

[0005] The mixed gas burners of blast furnace gas and converter gas in the lower layer are arranged on the four side walls, away from the pulverized coal burners in the four corners; the mixed gas burners of blast furnace gas and converter gas in the middle and upper layers are arranged in the middle of the burnout air in the four corners; the coke oven gas burners are arranged at the top secondary air inlet; the boiler economizer is upgraded to a finned economizer, and a fluoroplastic flue gas heat exchanger is added after the induced draft fan; the hot primary air duct at the air preheater outlet is opened, and part of the primary air is bypassed to the secondary air box through the bypass duct.

[0006] S2, Steam Turbine Modification: S21. Upgrade high and medium pressure valves and high and medium pressure inner and outer cylinders; modify the flow path of high, medium and low pressure cylinders; S22. The unit's feedwater pump is changed from an electric speed-regulating feedwater pump to a 100% steam-driven feedwater pump. The feedwater pump capacity is considered to have a 10% margin for normal unit operation. The original 50% electric speed-regulating feedwater pump is used for unit startup and standby. The power of the feedwater pump pre-pump motor is considered to have a 15% margin. S23. The radiator of the cooling unit of each unit is replaced from three rows of pipes to a single row of pipes.

[0007] Further modifications to the boiler heating surfaces include: Low-temperature superheater: Replace the heating surface of the vertical section; conduct anti-wear inspection on the horizontal section, replace pipes with excessive wear, and replace damaged anti-wear tiles; Full-screen superheater: The inlet section has been completely replaced with the original material, and the bottom and outlet tubes have been upgraded from 12Cr1MoVG to SA-213T91. Rear screen superheater: A throttling orifice is added to the rear screen inlet header; the material of the rear screen inlet section is T91, and the material of the bottom and outlet section pipes is upgraded from SA-213T91 to SA-213TP347H; the connecting pipe from the rear screen outlet header to the high-temperature superheater is replaced. High-temperature superheater: increased area; throttling orifice added to inlet header; inlet section material upgraded to SA-213T91, outlet section material upgraded to SA-213TP347H (shot peening); Wall-mounted reheater: The entire internal part of the furnace has been replaced; the material is the original 12Cr1MoVG. Intermediate temperature reheater: Complete upgrade and renovation, including replacement of the inlet header and renovation and upgrade of the outlet connection pipe. High-temperature reheater: material replacement at the inlet section, material upgrade inside the furnace, material upgrade outside the furnace at the outlet section, and replacement of the outlet header; Ceiling superheater: The ceiling pipes were replaced with new pipes; Economizer: Utilizing the existing header, the serpentine tubes are replaced with H-type finned tubes made of SA-210C material to increase the heating area and reduce the flue gas temperature; at the same time, an ultrasonic soot blower is added to prevent ash accumulation and blockage in the economizer; Water-cooled wall: Comprehensive repair and welding of the furnace seal to eliminate ash leakage and air leakage in the furnace.

[0008] Furthermore, the high and medium pressure valves are made of P91 steel, meeting the high temperature requirement of 566℃; the valve complete closing time is less than 0.3 seconds; and the inlet and outlet chamber profiles of the high and medium pressure inner and outer cylinders are optimized.

[0009] Furthermore, the high-pressure and low-pressure rotors are replaced with forged rotors without center holes. The dynamic and static blades adopt aerodynamic design to optimize the blade profile. The natural frequency of the frequency-modulated blades avoids the excitation frequency. The manufacturing and assembly precision of the blade root and shroud are strictly controlled. The blade profile is optimized to adapt to a wide range of back pressure changes and reduce blade loss fluctuations with flow rate and steam velocity.

[0010] Furthermore, the turbine bearings were replaced after the flow path modification: the support bearings adopted a combination of tilting pads and elliptical pads, and the thrust bearings could withstand the maximum thrust in both directions; at the same time, monitoring devices were installed on the bearing housings to monitor metal temperature, speed, vibration, shaft displacement, and differential expansion measurement points to ensure that the shaft system operating status is controllable in real time.

[0011] The beneficial effects of this invention are: 1. To ensure energy security, accelerate the transformation of the energy structure, and support the smooth achievement of carbon emission reduction targets, the project, after its upgrade, will be able to co-fire 300,000 Nm³ of high-efficiency mixed coal gas. 3 / h, coke oven gas 40,000 NM 3 With a capacity of approximately / h, the two units actually co-fire approximately 1.3 billion NM of coal gas annually. 3 / h (equivalent to blast furnace gas), reducing carbon emissions by 590,000 tons per year, and ensuring that steel companies have a complete supply of surplus gas.

[0012] 2. The significant reduction in coal consumption and fuel costs has enhanced the unit's competitiveness and expanded new profit points, resulting in an annual saving of 180,000 tons of standard coal after the upgrade.

[0013] 3. Significant environmental benefits: While reducing carbon dioxide emissions, it also reduces emissions of pollutants such as sulfur dioxide and nitrogen oxides, which has a direct positive effect on improving air quality and public health.

[0014] 4. It has promoted technological progress and industrial upgrading, opening up a new path for the transformation and development of coal-fired power units, especially the self-owned power plants of large steel enterprises. Attached Figure Description

[0015] Figure 1 This is a table of coal quality characteristics in the embodiments of the method of the present invention; Figure 2 This is a coal condition table in the method embodiment of the present invention. Detailed Implementation

[0016] The present invention will be further described below with reference to embodiments: A method for energy-saving and carbon-reducing retrofitting of traditional coal-fired power plants in steel enterprises' self-owned power plants includes: S1, pulverized coal and coal gas are co-fired, with a co-firing capacity of 150 kNm³. 3 / h blast furnace gas and converter gas mixture and 20kNm 3 / h coke oven gas; after blending with 150kNm3 / h of low-calorific-value gas, it is necessary to ensure that the main steam and reheat steam temperatures can reach the rated values ​​of 571 / 569℃ when the unit is at a load of 75% or higher.

[0017] The blast furnace gas and converter gas are mixed in a volume ratio of 30:4. After being mixed, the mixture is sent to the furnace front and then sent to the burner for combustion via a gas pipeline. Coke oven gas is transported by a separate pipeline.

[0018] When blending low-calorific-value blast furnace gas and converter gas, the calorific value of the gas is low, only 882 kcal / Nm3. As the blending amount increases, it will have an adverse effect on the overall performance of the unit. Due to the limitation of increasing the space for the gas burner nozzle, the new gas nozzle is considered to be in two layers, arranged below the pulverized coal nozzle; with a co-firing capacity of 150 kNm3 / h, without adjusting the pulverized coal nozzle, the residence time of pulverized coal in the furnace will be further shortened, the combustion of pulverized coal will be worse, and the carbon content of fly ash will further increase from the current 5.5%, resulting in increased mechanical unburned heat loss and decreased boiler efficiency.

[0019] Blending low-calorific-value blast furnace gas and converter gas will cause the flame center to shift further upwards, while the residence time of high-temperature flue gas in the furnace will be shortened, resulting in poorer pulverized coal combustion. Furthermore, the higher the blending rate, the higher the carbon content of the fly ash, leading to a decrease in boiler efficiency. To address the potential adverse effects of blending, this modification method generally does not adjust the pulverized coal burner. Instead, it reduces heat loss in the furnace and enhances combustion by arranging a protective combustion zone within the furnace; it minimizes the impact of blast furnace gas on coal combustion by selecting an appropriate blast furnace gas distribution ratio and location; and it optimizes the blast furnace gas nozzle design to improve the combustion of the blast furnace gas itself.

[0020] The boiler renovation includes: the mixed gas burners of blast furnace gas and converter gas in the lower layer are arranged on the four side walls, away from the pulverized coal burners in the four corners; the mixed gas burners of blast furnace gas and converter gas in the middle and upper layers are arranged in the middle of the burnout air in the four corners; and the coke oven gas burners are arranged at the top secondary air inlet.

[0021] The higher the amount of natural gas co-firing, the larger the flue gas volume, the higher the flue gas velocity at the convective heating surface, the stronger the convective heat transfer, and the larger the amount of desuperheating water required in the superheater, especially in the low-temperature superheater. Because there are no temperature control measures before the heating surface, the outlet steam temperature of the low-temperature superheater rises significantly, leading to a substantial increase in desuperheating water usage in both the superheater and reheater. Increasing boiler parameters can absorb this increased convective heat transfer, reducing the amount of desuperheating water needed. On the other hand, with increased natural gas co-firing, the amount of coal burned decreases, resulting in less primary air entering the pulverizing system. Therefore, the amount of primary air participating in heat exchange decreases, leading to an increase in boiler exhaust temperature and a decrease in boiler efficiency. To address the high exhaust temperature, the economizer is upgraded from a bare tube economizer to a finned economizer to increase heat absorption. Simultaneously, a fluoroplastic flue gas heat exchanger is added after the induced draft fan to further reduce the exhaust temperature, and the absorbed heat is used to heat the condensate.

[0022] However, the secondary air volume has increased. In order to make up for the insufficient secondary air volume, a hole is opened in the hot primary air duct at the air preheater outlet, and part of the primary air is bypassed to the secondary air box through the bypass duct to make up for the insufficient secondary air volume.

[0023] In addition, the modification of the boiler heating surface includes: Low-temperature superheater: Replace the heating surface of the vertical section; conduct anti-wear inspection on the horizontal section, replace pipes with excessive wear, and replace damaged anti-wear tiles; Full-screen superheater: The inlet section has been completely replaced with the original material, and the bottom and outlet tubes have been upgraded from 12Cr1MoVG to SA-213T91. Rear screen superheater: A throttling orifice is added to the rear screen inlet header; the material of the rear screen inlet section is T91, and the material of the bottom and outlet section pipes is upgraded from SA-213T91 to SA-213TP347H; the connecting pipe from the rear screen outlet header to the high-temperature superheater is replaced. High-temperature superheater: increased area; throttling orifice added to inlet header; inlet section material upgraded to SA-213T91, outlet section material upgraded to SA-213TP347H (shot peening); Wall-mounted reheater: The entire internal part of the furnace has been replaced; the material is the original 12Cr1MoVG. Intermediate temperature reheater: Complete upgrade and renovation, including replacement of the inlet header and renovation and upgrade of the outlet connection pipe. High-temperature reheater: material replacement at the inlet section, material upgrade inside the furnace, material upgrade outside the furnace at the outlet section, and replacement of the outlet header; Ceiling superheater: The ceiling pipes were replaced with new pipes; Economizer: Utilizing the existing header, the serpentine tubes are replaced with H-type finned tubes made of SA-210C material to increase the heating area and reduce the flue gas temperature; at the same time, an ultrasonic soot blower is added to prevent ash accumulation and blockage in the economizer; Water-cooled walls: Comprehensive repair and welding of the furnace seal to eliminate ash leakage and air leakage in the furnace; S2, Steam Turbine Modification: After the turbine upgrade, the main steam parameters were increased to 16.7 MPa / 566℃, and the reheat steam parameters were increased to 3.498 / 3.434 MPa (steam pump / electric pump) / 566℃. While retaining the low-pressure outer cylinder, unit foundation, and bearing housing, the upgrades included modifications to the high and medium pressure systems, energy-saving upgrades to the flow path, adaptation of the bypass and regenerative systems, and optimization of the feedwater system. This resulted in a dual improvement in the unit's deep peak-shaving capacity and thermal economy, ensuring that the 300MW nameplate capacity and original heating capacity remain unchanged. Specifically, this includes: S21. Upgrade high and medium pressure valves and high and medium pressure inner and outer cylinders; modify the flow path of high, medium and low pressure cylinders; The high and medium pressure valves are made of P91 steel, meeting the high temperature requirement of 566℃; the valve complete closing time is less than 0.3 seconds; the inlet and exhaust chamber profiles of the high and medium pressure inner and outer cylinders are optimized; the high, medium and low pressure rotors are replaced with forged rotors without center holes; the moving and stationary blades adopt aerodynamic design to optimize the blade profile; the natural frequency of the frequency-modulated blades avoids the excitation frequency; the manufacturing and assembly precision of the blade root and shroud are strictly controlled; the blade profile is optimized to adapt to a wide range of back pressure changes, reducing blade loss fluctuations with flow rate and steam velocity, and ensuring flow efficiency under different operating conditions; after the flow path modification, the turbine bearings are replaced: the support bearing adopts a combination of tilting pad and elliptical pad, and the thrust bearing can withstand the maximum thrust in both directions; at the same time, monitoring devices are installed on the bearing housing to monitor metal temperature, speed, vibration, shaft displacement, and expansion difference measurement points to ensure that the shaft system operating status is controllable in real time.

[0024] S22. The unit's feedwater pump is changed from an electric speed-regulating feedwater pump to a 100% steam-driven feedwater pump. The feedwater pump capacity is considered to have a 10% margin for normal unit operation. The original 50% capacity electric speed-regulating feedwater pump is used for unit startup and standby. The power of the feedwater pump pre-pump motor is considered to have a 15% margin. S23. Replace the three-row tube radiator of each unit's cooling unit with a single-row tube. This not only increases the heat exchange area but also makes it easier to clean, keeping the heated surface clean and enabling efficient heat exchange.

[0025] In addition, the traditional drive structure of the counter-flow fan was upgraded to high-efficiency and energy-saving permanent magnet technology, saving 15% of energy; an energy-saving cleaning robot for the cold end of the steam turbine was added to achieve automatic cleaning, ensure heat exchange effect, and reduce the back pressure of the unit by 15 kPa. Example

[0026] The method of this invention was used to modify Unit 1 and Unit 2 of the company's 300MW generating units. This modification was based on the verification of coal type, such as... Figure 1 Table 1-1 shows the design coal type for the modification, with a blending rate of 150 kNm³. 3 / h of blast furnace gas and converter gas mixture, plus 20kNm³ of additional gas. 3 / h coke oven gas; the volume ratio of blast furnace gas and converter gas is 30:4. After the gas is mixed, it is sent to the furnace front, and then the mixture is sent to the burner for combustion through the gas pipeline. Coke oven gas is transported by a separate pipeline. Gas conditions are as follows. Figure 2 As shown in Table 1-2.

[0027] Specific details of the renovation implementation: 1. Boiler Retrofit: Covering the three core systems of burner, gas transmission, and heating surface, and also providing a flue gas waste heat recovery system to address issues such as increased flue gas temperature after co-firing low-calorific-value gas.

[0028] (1) Burner modification: layered layout + double protection, adaptable to multiple fuel conditions. The modification concept of "layered layout and precise air distribution" is adopted, while strengthening safety interlock control.

[0029] (2) Gas transmission: source-separated connection + blending and control + safety isolation to ensure stable and safe supply. Blast furnace gas and converter gas are mixed. Coke oven gas is drawn from the existing coke oven gas pipeline network of Taiyuan Iron & Steel Group and distributed to boilers No. 1 and No. 2.

[0030] (3) Heating surface modification: material upgrade + structure optimization, improved adaptation parameters and anti-wear and anti-corrosion after co-firing 150kNm³ / h low calorific value coal gas and the main steam and reheat steam parameters are increased to 571℃ / 569℃ respectively.

[0031] (4) Flue gas waste heat recovery transformation: By adding fluoroplastic flue gas heat exchangers and optimizing the circulation system, the waste heat of flue gas can be utilized differently in the heating season and the non-heating season.

[0032] 2. Steam turbine modification (1) Cylinder valve innovation: redesign the high and medium pressure inner and outer cylinders, optimize the steam inlet and exhaust chambers, and reduce flow loss; replace the main steam valve and speed regulating steam valve to ensure rapid cut-off protection.

[0033] (2) Rotor blade optimization: Replace with a new forged rotor without a center hole, optimize the blade shape, and improve flow efficiency; use frequency-modulated blades to avoid excitation frequency and control assembly accuracy to prevent resonance; optimize the blade shape to adapt to back pressure changes and ensure flow efficiency.

[0034] (3) Upgrade of bearing system: Replace the turbine bearings while keeping the bearing housing unchanged; support bearings with tilting pads and elliptical pads, and thrust bearings with bidirectional maximum thrust; install monitoring devices on bearing seats to control the shaft system status in real time.

[0035] (4) Turbine bypass system upgrade: Replace the high and low bypass valves and supporting pipelines of the two units, and install a 40% capacity turbine bypass system.

[0036] (5) Adaptive modification of the regenerative extraction steam system: In order to make efficient use of the superheat of the three-stage extraction steam in the intermediate pressure cylinder, an external steam cooler was added; the high superheat of the extraction steam is used to heat the feedwater, and the steam after releasing the superheat enters the No. 3 high-pressure heater to continue heat exchange, which can reduce the unit's heat consumption rate by about 15kJ / kWh.

[0037] (6) Water supply system modification: Unit 2 will modify the No. 3 water supply pump to a 100% capacity steam-driven water supply pump, and the original two 50% capacity electric speed-regulating water supply pumps will be converted to start-up and standby.

[0038] 3. Four major pipeline renovation contents The original main steam, reheat cold section, and reheat hot section pipe walls were no longer sufficient to meet the strength requirements under high temperature and high pressure conditions, so the pipes were completely replaced. At the same time, after adding a 100% capacity steam-driven feedwater pump to the feedwater system, part of the main feedwater pipes were replaced to meet the feedwater delivery needs after the unit parameters were increased.

[0039] 4. Energy-saving optimization and retrofitting of the steam turbine cold end system The air-cooled tube bundle of the turbine cold-end system has been optimized and upgraded, replacing the three rows of tubes with a single row. This not only increases the heat exchange area but also facilitates cleaning, keeping the heated surfaces clean and improving heat exchange efficiency. The traditional drive structure of the counter-flow fan has been upgraded to high-efficiency and energy-saving permanent magnet technology. A new energy-saving cleaning robot for the turbine cold end has been added, along with an optimized vacuum pipeline condensation system.

[0040] The method of this invention firstly responds to the national policy of "carbon peaking and carbon neutrality", achieving the goals of energy conservation, emission reduction and comprehensive energy utilization, and meeting the needs of enterprises for sustainable development; secondly, it improves the operating efficiency of the unit, achieving coal saving and carbon reduction; and thirdly, it effectively ensures the normal consumption and emergency balance capacity of surplus coal gas in steel enterprises, achieving zero coal gas emission and reducing environmental pollution.

Claims

1. A method for energy-saving and carbon-reducing retrofitting of traditional coal-fired power plants in steel enterprises' self-owned power plants, characterized in that: include: S1, pulverized coal and coal gas are co-fired, with a co-firing capacity of 150 kNm³. 3 / h blast furnace gas and converter gas mixture and 20kNm 3 / h coke oven gas; after blending with 150kNm3 / h of low-calorific-value gas, it is necessary to ensure that the main steam and reheat steam temperatures can reach the rated values ​​of 571 / 569℃ when the unit is at a load of 75% or higher. S2, Steam Turbine Modification: S21. Upgrade high and medium pressure valves and high and medium pressure inner and outer cylinders; modify the flow path of high, medium and low pressure cylinders; S22. The unit's feedwater pump is changed from an electric speed-regulating feedwater pump to a 100% steam-driven feedwater pump. The feedwater pump capacity is considered to have a 10% margin for normal unit operation. The original 50% electric speed-regulating feedwater pump is used for unit startup and standby. The power of the feedwater pump pre-pump motor is considered to have a 15% margin. S23. The radiator of the cooling unit of each unit is replaced from three rows of pipes to a single row of pipes.

2. The method for energy-saving and carbon-reducing retrofitting of traditional coal-fired power plants in steel enterprises according to claim 1, characterized in that: The blast furnace gas and converter gas are mixed in a volume ratio of 30:

4. After being mixed, the mixture is sent to the furnace front and then sent to the burner for combustion via a gas pipeline. Coke oven gas is transported by a separate pipeline.

3. The method for energy conservation and carbon reduction retrofitting of traditional coal-fired power plants in steel enterprises according to claim 1, characterized in that: The S1 layer blast furnace gas and converter gas mixed gas burners are arranged on the four side walls, away from the four corner pulverized coal burners; the middle and upper layer blast furnace gas and converter gas mixed gas burners are arranged in the middle of the four corner burnout air; the coke oven gas burner is arranged at the top secondary air inlet; the boiler economizer is upgraded to a finned economizer, and a fluoroplastic flue gas heat exchanger is added after the induced draft fan; the air preheater outlet hot primary air duct is opened to bypass part of the primary air to the secondary air large air box through the bypass duct.

4. The method for energy conservation and carbon reduction retrofitting of traditional coal-fired power plants in steel enterprises according to claim 1, characterized in that: The boiler heating surface modification in S1 includes: Low-temperature superheater: Replace the heating surface of the vertical section; conduct anti-wear inspection on the horizontal section, replace pipes with excessive wear, and replace damaged anti-wear tiles; Full-screen superheater: The inlet section has been completely replaced with the original material, and the bottom and outlet tubes have been upgraded from 12Cr1MoVG to SA-213T91. Rear screen superheater: A throttling orifice is added to the rear screen inlet header; the material of the rear screen inlet section is T91, and the material of the bottom and outlet section pipes is upgraded from SA-213T91 to SA-213TP347H; the connecting pipe from the rear screen outlet header to the high-temperature superheater is replaced. High-temperature superheater: increased area; throttling orifice added to inlet header; inlet section material upgraded to SA-213T91, outlet section material upgraded to SA-213TP347H, surface shot peening treatment; Wall-mounted reheater: The entire internal part of the furnace has been replaced; the material is the original 12Cr1MoVG. Intermediate temperature reheater: Complete upgrade and renovation, including replacement of the inlet header and renovation and upgrade of the outlet connection pipe. High-temperature reheater: material replacement at the inlet section, material upgrade inside the furnace, material upgrade outside the furnace at the outlet section, and replacement of the outlet header; Ceiling superheater: The ceiling pipes were replaced with new pipes; Economizer: Utilizing the existing header, the serpentine tube is replaced with an H-type finned tube made of SA-210C material, and an additional set of acoustic soot blowers is added; Water-cooled wall: Comprehensive repair and welding of the furnace seal to eliminate ash leakage and air leakage in the furnace.

5. The method for energy conservation and carbon reduction retrofitting of traditional coal-fired power plants in steel enterprises according to claim 1, characterized in that: The S2 medium and high pressure valves are made of P91 steel, which meets the high temperature requirement of 566℃; the valve complete closing time is less than 0.3 seconds; the inlet and outlet air chamber profiles of the medium and high pressure inner and outer cylinders are optimized.

6. The method for energy conservation and carbon reduction retrofitting of traditional coal-fired power plants in steel enterprises' self-owned power plants according to claim 1, characterized in that: In S2, the high-pressure and low-pressure rotors are replaced with forged rotors without a center hole. The dynamic and static blades adopt aerodynamic design to optimize the blade profile. The natural frequency of the frequency-modulated blades avoids the excitation frequency. The manufacturing and assembly precision of the blade root and shroud are strictly controlled. The blade profile is optimized to adapt to a wide range of back pressure changes and reduce blade loss fluctuations with flow rate and steam velocity.

7. The method for energy conservation and carbon reduction retrofitting of traditional coal-fired power plants in steel enterprises according to claim 1, characterized in that: After the S2 flow path modification, the turbine bearings are replaced: the support bearing adopts a combination of tilting pads and elliptical pads, and the thrust bearing can withstand the maximum thrust in both directions; at the same time, a monitoring device is installed on the bearing housing to monitor metal temperature, speed, vibration, shaft displacement, and expansion difference measurement points to ensure that the shaft system operating status is controllable in real time.

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