A power generation system and operation method suitable for deep peak regulation

Abstract

The application discloses a power generation system and operation method suitable for deep peak regulation, and aims at solving the problems of small pressure difference of extraction steam at all levels, poor drainage of high and low pressure heaters and the like of a coal-fired unit during deep peak regulation operation, different operation load sections are divided, the operation characteristics of the unit under low load are considered, the thermal parameters of the unit are all deviated from the set values, different reconstruction modes of the regenerative system are adopted according to the load section where the unit load is located, the low-pressure regenerative system configuration is changed under low load, the high and low pressure regenerative system configurations are simultaneously changed under very low load, the drainage flow process of each heater is adjusted, and a drainage pump is reasonably installed, so that the loss of additional cold source is avoided, and the safe operation of the condenser and the cylinder body of the steam turbine is ensured. The application improves the smoothness of steam-water flow and the heat exchange matching under all working conditions of the unit, realizes the wide-load normal operation of the regenerative system of the unit, and improves the operation thermal economy and safety of the unit.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired power technology, specifically relating to a power generation system and operation method suitable for deep peak shaving. Background Technology

[0002] The turbine regenerative system is a core component of the thermal power plant's system. High- and low-pressure heaters utilize partial steam extraction from the turbine to heat feedwater and condensate, respectively, reducing the temperature difference between the working fluid entering the boiler and the furnace, minimizing heat transfer losses, and improving unit efficiency. Regenerative heater condensate drainage typically employs a staged gravity flow method, utilizing the inter-stage pressure difference between heater stages for normal drainage. Due to the rapid development of renewable energy, the peak-shaving depth of coal-fired units, as the main source of peak-shaving power, is increasing. As the unit's operating load decreases, the pressure difference between extraction stages decreases, increasing condensate drainage resistance, making the regenerative system highly susceptible to condensate blockages. When the emergency condensate valve is normally open, not only is a significant amount of high-grade heat energy lost from the high-energy condensate, severely impacting the unit's thermal economy, but if the low-pressure heater condensate directly enters the condenser, it increases the condenser's heat load and affects condenser vacuum. If the emergency condensate valve fails to open properly, there is a risk of water ingress into the turbine, threatening the unit's operational safety. Therefore, as deep-heating operation of coal-fired units becomes the norm, the problem of poor drainage in the regenerator system under deep-heating conditions will become increasingly prominent.

[0003] The thermal system configuration of coal-fired power units is designed by equipment manufacturers based on the rated load steady-state operating conditions, often without considering the transient processes of load changes and deep peak-shaving conditions. With the rapid development of unit capacity, and considering construction costs and investment, most units have eliminated the design of condensate pumps. In actual operation, under deep peak-shaving conditions, the unit's thermal parameters deviate from the set values, and the pressure difference of extraction steam at each stage at low loads makes it difficult to ensure the gradual gravity flow of condensate. Therefore, adjusting the thermal system configuration based on the operating characteristics of thermal parameters under low loads is expected to solve the problem of poor condensate drainage under deep peak-shaving conditions in coal-fired power units, improving the unit's operating economy and safety. Summary of the Invention

[0004] This invention aims to address the problems of poor drainage in the high and low pressure heaters of coal-fired power generation systems during deep peak shaving operations. It proposes a power generation system and operation method suitable for deep peak shaving. Considering the operating characteristics of the unit's thermodynamic parameters under low load, the configuration of the coal-fired power generation thermodynamic system is reconstructed. Based on different operating load ranges, the drainage process of each stage of the heater is adjusted to improve the smoothness of the steam-water working fluid flow and the heat exchange matching, thereby enabling the unit's regenerative system to operate normally under wide loads and improving the unit's operating economy and safety.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A power generation system suitable for deep peak shaving includes a boiler 1, a high-pressure cylinder of a steam turbine 2, a medium-pressure cylinder of a steam turbine 3, a low-pressure cylinder of a steam turbine 4, a generator 5, a condenser 6, a condensate pump 7, a fourth low-pressure heater 8, a third low-pressure heater 9, a second low-pressure heater 10, a first low-pressure heater 11, a feedwater pump turbine 12, a deaerator 13, a feedwater pump 14, a third high-pressure heater 15, a second high-pressure heater 16, a first high-pressure heater 17, a first drain regulating valve 18 of the second high-pressure heater, a second drain regulating valve 19 of the second high-pressure heater, a first drain regulating valve 20 of the third high-pressure heater, a second drain regulating valve 21 of the third high-pressure heater, a first drain regulating valve 22 of the first low-pressure heater, a second drain regulating valve 23 of the first low-pressure heater, a first drain regulating valve 24 of the second low-pressure heater, a second drain regulating valve 25 of the second low-pressure heater, a first drain regulating valve 28 of the third low-pressure heater, a second drain regulating valve 27 of the third low-pressure heater, and a drain pump 26 of the third low-pressure heater.

[0007] The superheated steam outlet of boiler 1 is connected to the steam inlet of the high-pressure cylinder 2 of the steam turbine via a pipeline. The first-stage extraction steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the first high-pressure heater 17 via a pipeline. The second-stage extraction steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the second high-pressure heater 16 via a pipeline. The steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the intermediate-pressure cylinder 3 of the steam turbine via boiler 1. The first-stage extraction steam outlet of the intermediate-pressure cylinder 3 is connected to the steam inlet of the third high-pressure heater 15 via a pipeline. The steam outlet of the steam turbine is connected to the steam inlet of the feedwater pump turbine 12 via a pipeline. The exhaust steam from the feedwater pump turbine 12 enters the condenser 6. The feedwater pump turbine 12 provides power to the feedwater pump 14. The third-stage extraction steam outlet of the intermediate-pressure cylinder 3 of the turbine is connected to the steam inlet of the deaerator 13 via a pipeline. The fourth-stage extraction steam outlet of the intermediate-pressure cylinder 3 of the turbine is connected to the steam inlet of the first low-pressure heater 11 via a pipeline. The steam outlet of the intermediate-pressure cylinder 3 of the turbine is connected to the steam inlet of the low-pressure cylinder 4 of the turbine via a pipeline. The first-stage extraction steam outlet of the low-pressure cylinder 4 of the turbine is connected to the second low-pressure heater. The steam inlet of the turbine is connected to the condenser 6 via a pipeline. The steam outlet of the second stage extraction steam of the turbine low-pressure cylinder 4 is connected to the steam inlet of the third low-pressure heater 9 via a pipeline. The steam outlet of the turbine low-pressure cylinder 4 is connected to the steam inlet of the fourth low-pressure heater 8 via a pipeline. The steam outlet of the turbine low-pressure cylinder 4 is connected to the condenser 6 via a pipeline. The condensate outlet of the condenser 6 is connected to the condensate inlet of the fourth low-pressure heater 8 via a condensate pump 7. The condensate flows through the fourth low-pressure heater 8, the third low-pressure heater 9, and the second low-pressure heater 10, respectively. The first low-pressure heater 11 and the condensate outlet of the first low-pressure heater 11 are connected to the feedwater inlet of the deaerator 13. The feedwater outlet of the deaerator 13 is connected to the feedwater inlet of the third high-pressure heater 15 through the feedwater pump 14. The feedwater flows through the third high-pressure heater 15, the second high-pressure heater 16 and the first high-pressure heater 17 respectively. The feedwater inlet of the boiler 1 is connected to the feedwater outlet of the first high-pressure heater 17. The high-pressure cylinder 2, the intermediate-pressure cylinder 3 and the low-pressure cylinder 4 of the turbine are coaxial and connected to the power grid through the generator 5.

[0008] The drain outlet of the second high-pressure heater 16 is connected to the drain inlet of the third high-pressure heater 15 via the first drain regulating valve 18 of the second high-pressure heater. The drain outlet of the second high-pressure heater 16 is connected to the feedwater medium at the outlet of the deaerator 13 via the second drain regulating valve 19 of the second high-pressure heater. The drain outlet of the third high-pressure heater 15 is connected to the drain inlet of the deaerator 13 via the first drain regulating valve 20 of the third high-pressure heater. The drain outlet of the third high-pressure heater 15 is connected to the drain inlet of the first low-pressure heater 11 via the second drain regulating valve 21 of the third high-pressure heater. The drain outlet of the first low-pressure heater 11 is connected to the drain inlet of the second low-pressure heater 10 via the first drain regulating valve 22 of the first low-pressure heater. The condensate outlet of device 11 is connected to the condensate inlet of the third low-pressure heater 9 through the second condensate regulating valve 23 of the first low-pressure heater. The condensate outlet of the second low-pressure heater 10 is connected to the condensate inlet of the third low-pressure heater 9 through the first condensate regulating valve 24 of the second low-pressure heater. The condensate outlet of the second low-pressure heater 10 is connected to the condensate inlet of the fourth low-pressure heater 8 through the second condensate regulating valve 25 of the second low-pressure heater. The condensate outlet of the third low-pressure heater 9 is connected to the condensate inlet of the fourth low-pressure heater 8 through the first condensate regulating valve 28 of the third low-pressure heater. The condensate outlet of the third low-pressure heater 9 returns to the condensate outlet of the third low-pressure heater 9 through the second condensate regulating valve 27 of the third low-pressure heater and the condensate pump 26 of the third low-pressure heater.

[0009] The aforementioned operating method for a power generation system suitable for deep peak shaving divides different operating load segments, considers the operating characteristics of coal-fired units under low load, and adopts different regenerative system reconfiguration methods according to the load segment where the coal-fired unit load is located:

[0010] When the coal-fired power unit operates within the range of 30% to 100% of its rated load, the configuration of the regenerative system remains unchanged. The differential pressure of each extraction steam stage is normal, and the drainage at each stage is unobstructed. The connection method is configuration 1: the drainage from the first high-pressure heater 17 flows to the second high-pressure heater 16; the first drainage regulating valve 18 of the second high-pressure heater is opened, and the second drainage regulating valve 19 of the second high-pressure heater is closed; the drainage from the second high-pressure heater 16 flows to the third high-pressure heater 15; the first drainage regulating valve 20 of the third high-pressure heater is opened, and the second drainage regulating valve 21 of the third high-pressure heater is closed; the drainage from the third high-pressure heater 15... Water flows to deaerator 13; the first drain regulating valve 22 of the first low-pressure heater is opened, and the second drain regulating valve 23 of the first low-pressure heater is closed, so the drain from the first low-pressure heater 11 flows to the second low-pressure heater 10; the first drain regulating valve 24 of the second low-pressure heater is opened, and the second drain regulating valve 25 of the second low-pressure heater is closed, so the drain from the second low-pressure heater 10 flows to the third low-pressure heater 9; the first drain regulating valve 28 of the third low-pressure heater is opened, and the second drain regulating valve 27 of the third low-pressure heater is closed, so the drain from the third low-pressure heater 9 flows to the fourth low-pressure heater 8, and the drain from the fourth low-pressure heater 8 flows to the first condenser 6;

[0011] When the unit load is within the range of 20%-30% of the rated load, the drainage process of each stage of the high-pressure heater is the same as configuration 1. According to the difference in the thermal parameters of the coal-fired unit under low load, the drainage process of each stage of the low-pressure heater is adjusted, and the connection method is configuration 2: the first drainage regulating valve 22 of the first low-pressure heater is closed, the second drainage regulating valve 23 of the first low-pressure heater is opened, and the drainage of the first low-pressure heater 11 flows to the third low-pressure heater 9; the first drainage regulating valve 24 of the second low-pressure heater is closed, the second drainage regulating valve 25 of the second low-pressure heater is opened, and the drainage of the second low-pressure heater 10 flows to the fourth low-pressure heater 8; the first drainage regulating valve 28 of the third low-pressure heater is closed, the second drainage regulating valve 27 of the third low-pressure heater is opened, and the drainage of the third low-pressure heater 9 flows to the condensate outlet of the third low-pressure heater 9 by the third low-pressure heater drainage pump 26;

[0012] When the unit load is below 20% of the rated load, the pressure difference of the extraction steam at each stage is small during extremely low load operation. The condensate flow of each stage of the low-pressure heater is the same as configuration 2. Adjust the condensate flow of each stage of the high-pressure heater and connect it in configuration 3: close the first condensate regulating valve 18 of the second high-pressure heater, open the second condensate regulating valve 19 of the second high-pressure heater, and the condensate of the second high-pressure heater 16 flows to the outlet of the deaerator 13; close the first condensate regulating valve 20 of the third high-pressure heater, open the second condensate regulating valve 21 of the third high-pressure heater, and the condensate of the third high-pressure heater 15 flows to the first low-pressure heater 11.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. This invention takes into account the operational characteristics of poor self-flow of condensate from the low-pressure heater in the regenerative system of a coal-fired unit under low load. Based on the matching of the thermodynamic parameters of the steam and water working fluid, the configuration of the low-load, low-pressure regenerative system is reconstructed. The condensate flow is rationally designed using a condensate pump, which not only broadens the normal operating range of the regenerative system, but also ensures the safe operation of the condenser and turbine cylinder.

[0015] 2. This invention takes into account the small pressure difference of the extraction steam at each stage of the high-pressure heater in the regenerative system under extremely low load of coal-fired unit, and adjusts the condensate connection method between each stage of high-pressure heater. Only the corresponding valves and pipelines need to be added, the system modification is small and the construction cost is low.

[0016] 3. This invention divides different operating load ranges and adopts different configuration adjustment methods according to different load ranges. The adjustment structure is simple, improves the smooth flow of steam and water working fluid and heat exchange matching under all operating conditions of the unit, realizes the normal operation of the unit's regenerative system under wide loads, and improves the unit's operating economy and safety. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a power generation system suitable for deep peak shaving;

[0018] Figure 2 This is a schematic diagram of different regenerative system configurations for a power generation system suitable for deep peak shaving. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] like Figure 1 As shown, a power generation system suitable for deep peak shaving includes a boiler 1, a high-pressure cylinder of a steam turbine 2, a medium-pressure cylinder of a steam turbine 3, a low-pressure cylinder of a steam turbine 4, a generator 5, a condenser 6, a condensate pump 7, a fourth low-pressure heater 8, a third low-pressure heater 9, a second low-pressure heater 10, a first low-pressure heater 11, a feedwater pump turbine 12, a deaerator 13, a feedwater pump 14, a third high-pressure heater 15, a second high-pressure heater 16, a first high-pressure heater 17, a first drain regulating valve 18 of the second high-pressure heater, a second drain regulating valve 19 of the second high-pressure heater, a first drain regulating valve 20 of the third high-pressure heater, a second drain regulating valve 21 of the third high-pressure heater, a first drain regulating valve 22 of the first low-pressure heater, a second drain regulating valve 23 of the first low-pressure heater, a first drain regulating valve 24 of the second low-pressure heater, a second drain regulating valve 25 of the second low-pressure heater, a first drain regulating valve 28 of the third low-pressure heater, a second drain regulating valve 27 of the third low-pressure heater, and a drain pump 26 of the third low-pressure heater.

[0021] The superheated steam outlet of boiler 1 is connected to the steam inlet of the high-pressure cylinder 2 of the steam turbine via a pipeline. The first-stage extraction steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the first high-pressure heater 17 via a pipeline. The second-stage extraction steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the second high-pressure heater 16 via a pipeline. The steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the intermediate-pressure cylinder 3 of the steam turbine via boiler 1. The first-stage extraction steam outlet of the intermediate-pressure cylinder 3 is connected to the steam inlet of the third high-pressure heater 15 via a pipeline. The steam outlet of the steam turbine is connected to the steam inlet of the feedwater pump turbine 12 via a pipeline. The exhaust steam from the feedwater pump turbine 12 enters the condenser 6. The feedwater pump turbine 12 provides power to the feedwater pump 14. The third-stage extraction steam outlet of the intermediate-pressure cylinder 3 of the turbine is connected to the steam inlet of the deaerator 13 via a pipeline. The fourth-stage extraction steam outlet of the intermediate-pressure cylinder 3 of the turbine is connected to the steam inlet of the first low-pressure heater 11 via a pipeline. The steam outlet of the intermediate-pressure cylinder 3 of the turbine is connected to the steam inlet of the low-pressure cylinder 4 of the turbine via a pipeline. The first-stage extraction steam outlet of the low-pressure cylinder 4 of the turbine is connected to the second low-pressure heater. The steam inlet of the turbine is connected to the condenser 6 via a pipeline. The steam outlet of the second stage extraction steam of the turbine low-pressure cylinder 4 is connected to the steam inlet of the third low-pressure heater 9 via a pipeline. The steam outlet of the turbine low-pressure cylinder 4 is connected to the steam inlet of the fourth low-pressure heater 8 via a pipeline. The steam outlet of the turbine low-pressure cylinder 4 is connected to the condenser 6 via a pipeline. The condensate outlet of the condenser 6 is connected to the condensate inlet of the fourth low-pressure heater 8 via a condensate pump 7. The condensate flows through the fourth low-pressure heater 8, the third low-pressure heater 9, and the second low-pressure heater 10, respectively. The first low-pressure heater 11 and the condensate outlet of the first low-pressure heater 11 are connected to the feedwater inlet of the deaerator 13. The feedwater outlet of the deaerator 13 is connected to the feedwater inlet of the third high-pressure heater 15 through the feedwater pump 14. The feedwater flows through the third high-pressure heater 15, the second high-pressure heater 16 and the first high-pressure heater 17 respectively. The feedwater inlet of the boiler 1 is connected to the feedwater outlet of the first high-pressure heater 17. The high-pressure cylinder 2, the intermediate-pressure cylinder 3 and the low-pressure cylinder 4 of the turbine are coaxial and connected to the power grid through the generator 5.

[0022] The drain outlet of the second high-pressure heater 16 is connected to the drain inlet of the third high-pressure heater 15 via the first drain regulating valve 18 of the second high-pressure heater. The drain outlet of the second high-pressure heater 16 is connected to the feedwater medium at the outlet of the deaerator 13 via the second drain regulating valve 19 of the second high-pressure heater. The drain outlet of the third high-pressure heater 15 is connected to the drain inlet of the deaerator 13 via the first drain regulating valve 20 of the third high-pressure heater. The drain outlet of the third high-pressure heater 15 is connected to the drain inlet of the first low-pressure heater 11 via the second drain regulating valve 21 of the third high-pressure heater. The drain outlet of the first low-pressure heater 11 is connected to the drain inlet of the second low-pressure heater 10 via the first drain regulating valve 22 of the first low-pressure heater. The condensate outlet of device 11 is connected to the condensate inlet of the third low-pressure heater 9 through the second condensate regulating valve 23 of the first low-pressure heater. The condensate outlet of the second low-pressure heater 10 is connected to the condensate inlet of the third low-pressure heater 9 through the first condensate regulating valve 24 of the second low-pressure heater. The condensate outlet of the second low-pressure heater 10 is connected to the condensate inlet of the fourth low-pressure heater 8 through the second condensate regulating valve 25 of the second low-pressure heater. The condensate outlet of the third low-pressure heater 9 is connected to the condensate inlet of the fourth low-pressure heater 8 through the first condensate regulating valve 28 of the third low-pressure heater. The condensate outlet of the third low-pressure heater 9 returns to the condensate outlet of the third low-pressure heater 9 through the second condensate regulating valve 27 of the third low-pressure heater and the condensate pump 26 of the third low-pressure heater.

[0023] The aforementioned operating method for a power generation system suitable for deep peak shaving divides different operating load segments, considers the operating characteristics of coal-fired units under low load, and adopts different regenerative system reconfiguration methods according to the load segment where the coal-fired unit load is located:

[0024] Taking a 660MW single-reheat coal-fired power unit as an example, when the unit is operating within the range of 30% to 100% of its rated load, the operating values ​​of the extraction steam pressures at each stage of the high-pressure cylinder are 2.37MPa and 1.71MPa, respectively, while the design values ​​are 2.33MPa and 1.78MPa. The operating values ​​of the extraction steam thermodynamic parameters at each stage are basically consistent with the set values. The operating values ​​of the extraction steam pressures at each stage of the intermediate-pressure cylinder are 0.81MPa, 0.36MPa, and 0.11MPa, respectively, while the design values ​​are 0.85MPa, 0.41MPa, and 0.18MPa. The operating values ​​of the extraction steam thermodynamic parameters at each stage have small deviations from the set values. The extraction steam differential pressure at each stage of the low-pressure cylinder is also in normal operating condition, and the drainage is unobstructed. Therefore, the configuration of the regenerative system of the coal-fired power unit remains unchanged, and the connection method of the coal-fired power unit is configuration 1. Figure 2As shown: the condensate from the first high-pressure heater 17 flows to the second high-pressure heater 16; the first condensate regulating valve 18 of the second high-pressure heater is opened, and the second condensate regulating valve 19 of the second high-pressure heater is closed; the condensate from the second high-pressure heater 16 flows to the third high-pressure heater 15; the first condensate regulating valve 20 of the third high-pressure heater is opened, and the second condensate regulating valve 21 of the third high-pressure heater is closed; the condensate from the third high-pressure heater 15 flows to the deaerator 13; the first condensate regulating valve 22 of the first low-pressure heater is opened, and the second condensate regulating valve 23 of the first low-pressure heater is closed; the condensate from the first low-pressure heater 11 flows to the second low-pressure heater 10; the first condensate regulating valve 24 of the second low-pressure heater is opened, and the second condensate regulating valve 25 of the second low-pressure heater is closed; the condensate from the second low-pressure heater 10 flows to the third low-pressure heater 9; the first condensate regulating valve 28 of the third low-pressure heater is opened, and the second condensate regulating valve 27 of the third low-pressure heater is closed; the condensate from the third low-pressure heater 9 flows to the fourth low-pressure heater 8; the condensate from the fourth low-pressure heater 8 flows to the condenser 6.

[0025] When the unit load is within the range of 20%-30% of rated load, the pressure difference between each stage of the high-pressure heater can still maintain smooth drainage. Therefore, the drainage process of each stage of the high-pressure heater is the same as configuration 1. However, due to the lower operating load and lower extraction steam pressure between each stage of the low-pressure cylinder, drainage problems are very likely to occur. Therefore, in response to the operating characteristic of poor gravity flow of drainage in the low-pressure heater, the drainage process of each stage of the low-pressure heater is adjusted, and the connection method is configuration 2, such as... Figure 2 As shown: the first drain regulating valve 22 of the first low-pressure heater is closed, and the second drain regulating valve 23 of the first low-pressure heater is opened, so that the drain water from the first low-pressure heater 11 flows to the third low-pressure heater 9; the first drain regulating valve 24 of the second low-pressure heater is closed, and the second drain regulating valve 25 of the second low-pressure heater is opened, so that the drain water from the second low-pressure heater 10 flows to the fourth low-pressure heater 8; the first drain regulating valve 28 of the third low-pressure heater is closed, and the second drain regulating valve 27 of the third low-pressure heater is opened, so that the drain water from the third low-pressure heater 9 flows to the condensate outlet of the third low-pressure heater 9 by the drain pump 26. For the drain water of the third low-pressure heater, the drain pump is used to change the drain flow, which can broaden the normal operating range of the regenerative system while ensuring the safe operation of the condenser and the turbine cylinder.

[0026] When the unit operates at less than 20% of its rated load, the thermal parameters of each stage of the unit have deviated significantly from the design values. The extraction steam pressure difference between the high, intermediate, and low-pressure cylinders of the turbine is extremely small, and the problem of poor interstage drainage will seriously endanger the safe operation of the unit. Therefore, the drainage process of each stage of the low-pressure heater is designed to be the same as configuration 2, while the drainage process of each stage of the high-pressure heater is adjusted, and the connection method is configuration 3. Figure 2As shown: the first drain regulating valve 18 of the second high-pressure heater is closed, and the second drain regulating valve 19 of the second high-pressure heater is opened, so that the drain of the second high-pressure heater 16 flows to the outlet of the deaerator 13; the first drain regulating valve 20 of the third high-pressure heater is closed, and the second drain regulating valve 21 of the third high-pressure heater is opened, so that the drain of the third high-pressure heater 15 flows to the first low-pressure heater 11. For the reconstruction of the drain process of the high-pressure regenerative system, only the corresponding valves and pipes need to be added, the system modification is small and the construction cost is low.

[0027] By employing different regenerative system reconfiguration methods, adjusting the condensate drainage process of each stage of the heater, and rationally installing condensate pumps, additional cold source losses are avoided while ensuring the safe operation of the condenser and turbine cylinder. This invention can improve the smoothness of steam-water working fluid flow and heat exchange matching under all operating conditions of the unit, enabling the regenerative system to operate normally under wide loads, and improving the unit's thermal economy and safety.

Claims

1. A power generation system suitable for deep peak shaving, characterized in that: Includes a boiler (1), a high-pressure cylinder of a steam turbine (2), an intermediate-pressure cylinder of a steam turbine (3), a low-pressure cylinder of a steam turbine (4), a generator (5), a condenser (6), a condensate pump (7), a fourth low-pressure heater (8), a third low-pressure heater (9), a second low-pressure heater (10), a first low-pressure heater (11), a feedwater pump turbine (12), a deaerator (13), a feedwater pump (14), a third high-pressure heater (15), a second high-pressure heater (16), a first high-pressure heater (17), and a first drain regulating valve for the second high-pressure heater (18). The second high-pressure heater second drain regulating valve (19), the third high-pressure heater first drain regulating valve (20), the third high-pressure heater second drain regulating valve (21), the first low-pressure heater first drain regulating valve (22), the first low-pressure heater second drain regulating valve (23), the second low-pressure heater first drain regulating valve (24), the second low-pressure heater second drain regulating valve (25), the third low-pressure heater first drain regulating valve (28), the third low-pressure heater second drain regulating valve (27), and the third low-pressure heater drain pump (26); The superheated steam outlet of the boiler (1) is connected to the steam inlet of the high-pressure cylinder (2) of the steam turbine via a pipeline. The first-stage extraction steam outlet of the high-pressure cylinder (2) of the steam turbine is connected to the steam inlet of the first high-pressure heater (17) via a pipeline. The second-stage extraction steam outlet of the high-pressure cylinder (2) of the steam turbine is connected to the steam inlet of the second high-pressure heater (16) via a pipeline. The steam outlet of the high-pressure cylinder (2) of the steam turbine is connected to the steam inlet of the intermediate-pressure cylinder (3) of the steam turbine via the boiler (1). The first-stage extraction steam outlet of the intermediate-pressure cylinder (3) of the steam turbine is connected to the steam inlet of the third high-pressure heater (15) via a pipeline. The second-stage extraction steam outlet of the intermediate-pressure cylinder (3) of the steam turbine... The steam inlet of the feedwater pump turbine (12) is connected to the steam inlet of the feedwater pump turbine (12) through a pipeline. The exhaust steam of the feedwater pump turbine (12) enters the condenser (6). The feedwater pump turbine (12) provides power to the feedwater pump (14). The third-stage extraction steam outlet of the intermediate-pressure cylinder (3) of the turbine is connected to the steam inlet of the deaerator (13) through a pipeline. The fourth-stage extraction steam outlet of the intermediate-pressure cylinder (3) of the turbine is connected to the steam inlet of the first low-pressure heater (11) through a pipeline. The steam outlet of the intermediate-pressure cylinder (3) of the turbine is connected to the steam inlet of the low-pressure cylinder (4) of the turbine through a pipeline. The first-stage extraction steam outlet of the low-pressure cylinder (4) of the turbine is connected to the second low-pressure heater (10). The steam inlet of the turbine is connected to the steam inlet of the third low-pressure heater (9) via a pipeline. The steam outlet of the turbine low-pressure cylinder (4) is connected to the steam inlet of the fourth low-pressure heater (8) via a pipeline. The steam outlet of the turbine low-pressure cylinder (4) is connected to the condenser (6) via a pipeline. The condensate outlet of the condenser (6) is connected to the condensate inlet of the fourth low-pressure heater (8) via a condensate pump (7). The condensate flows through the fourth low-pressure heater (8), the third low-pressure heater (9), the second low-pressure heater (10), and the first low-pressure heater (11). The condensate outlet of the first low-pressure heater (11) is connected to the feedwater inlet of the deaerator (13). The feedwater outlet of the deaerator (13) is connected to the feedwater inlet of the third high-pressure heater (15) via a feedwater pump (14). The feedwater flows through the third high-pressure heater (15), the second high-pressure heater (16), and the first high-pressure heater (17), respectively. The feedwater inlet of the boiler (1) is connected to the feedwater outlet of the first high-pressure heater (17). The high-pressure cylinder (2), the intermediate-pressure cylinder (3), and the low-pressure cylinder (4) of the turbine are coaxial and connected to the power grid via a generator (5). The drain outlet of the second high-pressure heater (16) is connected to the drain inlet of the third high-pressure heater (15) through the first drain regulating valve (18) of the second high-pressure heater. The drain outlet of the second high-pressure heater (16) is connected to the feed water medium at the outlet of the deaerator (13) through the second drain regulating valve (19) of the second high-pressure heater. The drain outlet of the third high-pressure heater (15) is connected to the drain inlet of the deaerator (13) through the first drain regulating valve (20) of the third high-pressure heater. The drain outlet of the third high-pressure heater (15) is connected to the drain inlet of the first low-pressure heater (11) through the second drain regulating valve (21) of the third high-pressure heater. The drain outlet of the first low-pressure heater (11) is connected to the drain inlet of the second low-pressure heater (10) through the first drain regulating valve (22) of the first low-pressure heater. The drain outlet of (11) is connected to the drain inlet of the third low-pressure heater (9) through the second drain regulating valve (23) of the first low-pressure heater. The drain outlet of the second low-pressure heater (10) is connected to the drain inlet of the third low-pressure heater (9) through the first drain regulating valve (24) of the second low-pressure heater. The drain outlet of the second low-pressure heater (10) is connected to the drain inlet of the fourth low-pressure heater (8) through the second drain regulating valve (25) of the second low-pressure heater. The drain outlet of the third low-pressure heater (9) is connected to the drain inlet of the fourth low-pressure heater (8) through the first drain regulating valve (28) of the third low-pressure heater. The drain outlet of the third low-pressure heater (9) returns to the condensate outlet of the third low-pressure heater (9) through the second drain regulating valve (27) of the third low-pressure heater and the drain pump (26) of the third low-pressure heater.

2. The operation method of a power generation system suitable for deep peak shaving as described in claim 1, characterized in that, Different operating load zones were defined, and considering the operating characteristics of coal-fired units under low load, different regenerative system reconfiguration methods were adopted according to the load zone in which the coal-fired unit load was located: When the coal-fired power unit operates within the range of 30% to 100% of its rated load, the configuration of the regenerative system remains unchanged. The differential pressure of the extraction steam at each stage of the coal-fired power unit is normal, and the drainage at each stage is unobstructed. The connection method is configuration 1: the drainage from the first high-pressure heater (17) flows to the second high-pressure heater (16), the first drainage regulating valve (18) of the second high-pressure heater is opened, the second drainage regulating valve (19) of the second high-pressure heater is closed, and the drainage from the second high-pressure heater (16) flows to the third high-pressure heater (15); the first drainage regulating valve (20) of the third high-pressure heater is opened, the second drainage regulating valve (21) of the third high-pressure heater is closed, and the drainage from the third high-pressure heater (15) flows to the deaerator. (13); Open the first drain regulating valve (22) of the first low-pressure heater, close the second drain regulating valve (23) of the first low-pressure heater, and the drain of the first low-pressure heater (11) flows to the second low-pressure heater (10); Open the first drain regulating valve (24) of the second low-pressure heater, close the second drain regulating valve (25) of the second low-pressure heater, and the drain of the second low-pressure heater (10) flows to the third low-pressure heater (9); Open the first drain regulating valve (28) of the third low-pressure heater, close the second drain regulating valve (27) of the third low-pressure heater, and the drain of the third low-pressure heater (9) flows to the fourth low-pressure heater (8), and the drain of the fourth low-pressure heater (8) flows to the first condenser (6); When the unit load is within the range of 20% to 30% of the rated load, the drainage process of each stage of the high-pressure heater is the same as configuration 1. According to the difference in the thermal parameters of the coal-fired unit under low load, the drainage process of each stage of the low-pressure heater is adjusted. The connection method is configuration 2: the first drainage regulating valve (22) of the first low-pressure heater is closed, the second drainage regulating valve (23) of the first low-pressure heater is opened, and the drainage of the first low-pressure heater (11) flows to the third low-pressure heater (9); the first drainage regulating valve (24) of the second low-pressure heater is closed, the second drainage regulating valve (25) of the second low-pressure heater is opened, and the drainage of the second low-pressure heater (10) flows to the fourth low-pressure heater (8); the first drainage regulating valve (28) of the third low-pressure heater is closed, the second drainage regulating valve (27) of the third low-pressure heater is opened, and the drainage of the third low-pressure heater (9) flows to the condensate outlet of the third low-pressure heater (9) by the drainage pump (26) of the third low-pressure heater. When the unit load is below 20% of the rated load, the pressure difference of the extraction steam at each stage is small during extremely low load operation. The condensate flow of each stage of the low-pressure heater is the same as that of configuration 2. Adjust the condensate flow of each stage of the high-pressure heater and connect it in configuration 3: close the first condensate regulating valve (18) of the second high-pressure heater, open the second condensate regulating valve (19) of the second high-pressure heater, and the condensate of the second high-pressure heater (16) flows to the outlet of the deaerator (13); close the first condensate regulating valve (20) of the third high-pressure heater, open the second condensate regulating valve (21) of the third high-pressure heater, and the condensate of the third high-pressure heater (15) flows to the first low-pressure heater (11).

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