Thermal power generating unit output depth adjustable thermal power control system and method
By modifying the thermal system and controlling the valves of the thermal power unit, the problems of uncontrollable axial thrust, excessively high exhaust temperature, and inability of the denitrification system to operate normally during low-output operation of the thermal power unit were solved, realizing in-depth adjustment and flexible operation of the unit.
Patent Information
- Application Number
- CN202512029700.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-02-24
AI Technical Summary
When thermal power units operate at low output, they face problems such as uncontrollable turbine axial thrust, excessively high exhaust temperatures in the high, medium, and low pressure cylinders, and the inability of the denitrification system to operate normally, which limits the ability to adjust the output depth.
By controlling the pipeline connections and valves of the high-pressure cylinder, medium-pressure cylinder, low-pressure cylinder, boiler, condenser, condensate pump, low-pressure heater, deaerator, feedwater pump, third high-pressure heater, second high-pressure heater, first high-pressure heater, economizer, and denitrification system, steam distribution and regulation are achieved, ensuring reasonable work and cooling of each cylinder under deep peak shaving conditions, and ensuring the normal operation of the denitrification system.
It achieves controllable turbine axial thrust under deep peak shaving conditions, normal exhaust steam temperature of high, medium and low pressure cylinders, normal operation of denitrification system, and improved power output depth adjustment capability of thermal power unit to meet flexible operation requirements.
Smart Images
Figure CN121556958A_ABST
Abstract
Description
Technical Field
[0001] This invention provides a thermal control system and method for thermal power unit output that can be deeply adjusted, belonging to the field of thermal control technology for thermal power units. Background Technology
[0002] With the integration of a large amount of renewable energy into the grid, thermal power units are gradually transforming from power-generating sources to sources that provide both basic security and system regulation. Fully utilizing existing thermal power units for peak-shaving retrofits or flexibly manufacturing new thermal power units can effectively promote the absorption of renewable energy. Upgrading and optimizing the thermal system can effectively improve the output depth regulation capability of thermal power units. However, the factors currently restricting the output depth regulation of thermal power units include: 1. The steam flowing through the high-pressure and intermediate-pressure rotor of the steam turbine is usually arranged in reverse. When the thermal power unit is operating at low output, the mismatch between the output of the high-pressure and intermediate-pressure cylinders leads to uncontrollable axial thrust of the steam turbine, which poses an operational safety risk. 2. When the thermal power unit is operating at low output, the reduced steam flow into the high, medium and low pressure cylinders can easily lead to insufficient cooling of the rear rotor blades in the high, medium and low pressure cylinders, resulting in excessively high exhaust steam temperatures in the high, medium and low pressure cylinders. Third, when the thermal power unit is operating at low output, the boiler feedwater temperature will be lower due to the reduction in extraction steam parameters. After the feedwater absorbs heat in the economizer, the inlet flue gas temperature of the denitrification system is below 300℃, which is lower than the minimum temperature limit of the catalyst, affecting the normal operation of the denitrification system.
[0003] The aforementioned problems will limit the ability of thermal power units to adjust their output depth. To overcome this deficiency, it is urgent to develop a new type of thermal power unit output depth adjustable thermodynamic control system and method. Summary of the Invention
[0004] To address the technical problems existing in the background art, the present invention adopts the following technical solution: A thermal power unit output control system with deeply adjustable output is provided, comprising a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a boiler, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, a third high-pressure heater, a second high-pressure heater, a first high-pressure heater, an economizer, and a denitrification system, wherein: The steam side of the boiler is connected to the inlet of the high-pressure cylinder through a steam pipeline equipped with a first valve. The boiler is also connected to the middle of the high-pressure cylinder through a steam pipeline equipped with a ninth valve. The opening in the middle of the high-pressure cylinder is located between the inlet of the high-pressure cylinder and the first steam extraction port of the high-pressure cylinder. The steam side of the boiler is connected to the inlet of the intermediate pressure cylinder through a steam pipeline equipped with a third valve. The boiler is also connected to the middle of the intermediate pressure cylinder through a steam pipeline equipped with a tenth valve. The opening in the middle of the intermediate pressure cylinder is located between the inlet of the intermediate pressure cylinder and the third steam extraction port of the intermediate pressure cylinder. The high-pressure cylinder is connected to the first high-pressure heater through a first extraction steam pipeline equipped with a fifth valve and a sixth valve. The high-pressure cylinder is connected to the boiler via a steam exhaust pipe equipped with a second valve; The high-pressure cylinder is connected to the second high-pressure heater via a second extraction steam pipeline equipped with a seventh valve. The intermediate pressure cylinder is connected to the third high pressure heater through a third extraction steam pipeline equipped with an eleventh valve and an eighth valve. The intermediate-pressure cylinder is connected to the deaerator via a steam pipeline; The intermediate pressure cylinder is connected to the deaerator via the fourth extraction steam pipeline; The medium-pressure cylinder is connected to the low-pressure cylinder through a medium-low pressure connecting pipe equipped with a fourth valve; The intermediate-pressure cylinder is connected to the low-pressure cylinder's low-pressure injection and extraction steam pipeline via a steam pipeline; The low-pressure cylinder is connected to the deaerator via a steam pipeline equipped with a twelfth valve. The low-pressure cylinder is connected to the low-pressure heater via a steam pipeline equipped with a thirteenth valve. The low-pressure cylinder is also connected in sequence to a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, a third high-pressure heater, a second high-pressure heater, a first high-pressure heater, an economizer, and a boiler via pipelines. The flue gas side of the boiler is connected to the denitrification system via the economizer.
[0005] A thermal control method for deeply adjustable output of a thermal power unit includes a control method for the thermal power unit operating under non-deep peak-shaving conditions, the specific steps of which are as follows: The first, second, third, fourth, fifth, sixth, seventh, eighth, and twelfth valves are all in the open state, while the ninth, tenth, and eleventh valves are all in the closed state. The steam generated by the boiler enters the high-pressure cylinder inlet through the first valve to do work. The exhaust steam from the high-pressure cylinder enters the boiler for reheating through the second valve. The reheated steam enters the intermediate-pressure cylinder inlet through the third valve to do work. The exhaust steam from the intermediate-pressure cylinder enters the low-pressure cylinder through the fourth valve on the medium-low pressure connecting pipe to continue doing work. The exhaust steam from the low-pressure cylinder enters the condenser and condenses into water. After passing through the condensate pump, low-pressure heater, deaerator, feedwater pump, third high-pressure heater, second high-pressure heater, first high-pressure heater, and economizer, it enters the boiler for further heating. The first stage of high-pressure cylinder extraction steam enters the first high-pressure heater through the first extraction steam pipeline equipped with the fifth and sixth valves; The second stage of high-pressure cylinder extraction steam enters the second high-pressure heater through the second extraction steam pipeline equipped with the seventh valve; The steam extracted from the first stage of the intermediate pressure cylinder enters the third high-pressure heater through the third extraction pipeline equipped with the eleventh and eighth valves. The second stage of steam extraction from the intermediate pressure cylinder enters the deaerator through the fourth extraction pipeline. Steam extracted from the low-pressure cylinder enters the low-pressure heater through the low-pressure heater extraction pipeline equipped with the thirteenth valve; The flue gas generated by boiler combustion enters the denitrification system after passing through the economizer.
[0006] A thermal control method for deeply adjustable output of a thermal power unit includes a control method for the thermal power unit operating under deep peak-shaving conditions, the specific steps of which are as follows: Gradually close the first valve to reduce the amount of main steam entering the high-pressure cylinder inlet to perform work. Slowly open the ninth valve to increase the amount of main steam entering from the middle of the high-pressure cylinder. Mix the steam that has already done work in the high-pressure cylinder with the steam that has already done work in the high-pressure cylinder and continue to do work in the high-pressure cylinder. After the parameters are improved, part of the steam enters the first high-pressure heater through the first extraction steam pipeline equipped with the fifth and sixth valves, which increases the feedwater temperature at the high-pressure heater outlet, reduces the heat absorption of the feedwater in the economizer, and ensures the normal operation of the denitrification system. The remaining steam continues to do work in the high-pressure cylinder, cooling the rear rotor blades in the high-pressure cylinder while controlling the axial displacement of the steam turbine within the required range, preventing the exhaust temperature of the high-pressure cylinder from being too high. After that, part of the exhaust steam from the high-pressure cylinder still flows through the second extraction steam pipeline equipped with the seventh valve into the second high-pressure heater, and most of the exhaust steam from the high-pressure cylinder flows through the second valve into the boiler for reheating. When the unit is operating under stable peak-shaving conditions, and the turbine axial displacement and high-pressure cylinder exhaust temperature are normal, the first valve is completely closed, and the output is adjusted through the ninth valve. The third valve is gradually closed to reduce the amount of reheat steam entering the intermediate-pressure cylinder inlet to perform work; Slowly open the tenth valve to increase the amount of reheat steam entering from the middle of the intermediate pressure cylinder. Mix the reheat steam with the steam that has already done work in the intermediate pressure cylinder and continue to do work in the intermediate pressure cylinder. Part of the mixed steam still enters the third high-pressure heater through the third extraction pipeline equipped with the eleventh and eighth valves, and part of the mixed steam enters the deaerator through the fourth extraction pipeline. While controlling the axial displacement of the steam turbine within the required range, the blades of the rear rotor inside the intermediate pressure cylinder are cooled to prevent the exhaust temperature of the intermediate pressure cylinder from becoming too high. When the unit is operating under stable deep peak shaving conditions, and the turbine axial displacement and intermediate pressure cylinder exhaust temperature are normal, the third valve is completely closed, and the reheat steam parameters are adjusted through the tenth valve. The fourth valve is gradually closed to reduce the amount of steam entering the low-pressure cylinder to continue doing work through the fourth valve on the medium-low pressure connecting pipe; Slowly open the eleventh valve to allow some of the steam from the intermediate-pressure cylinder to enter the middle of the low-pressure cylinder and mix with the steam that has already done work in the low-pressure cylinder. Then, it will continue to do work in the low-pressure cylinder. At the same time, it will cool the blades of the rotor at the rear of the low-pressure cylinder to prevent the steam temperature from becoming too high. Part of the exhaust steam from the intermediate-pressure cylinder enters the low-pressure heater through the low-pressure heater extraction pipeline equipped with the thirteenth valve; When the unit is in a stable deep peak shaving condition and the low-pressure cylinder exhaust temperature is normal, the fourth valve is completely closed, and the steam parameters of the middle steam inlet of the low-pressure cylinder are adjusted by controlling the eleventh valve. During the adjustment process, the first valve is gradually closed to reduce the amount of main steam entering from the high-pressure cylinder inlet to perform work, while the ninth valve is slowly opened to increase the amount of main steam entering from the middle of the high-pressure cylinder. The third valve is gradually closed to reduce the amount of reheat steam entering from the intermediate-pressure cylinder inlet to perform work, while the tenth valve is slowly opened to increase the amount of reheat steam entering from the middle of the intermediate-pressure cylinder. The axial displacement of the turbine is coordinated and controlled within the required range. During the adjustment process, the fourth valve is gradually closed to reduce the amount of steam entering the low-pressure cylinder through the fourth valve on the medium-low pressure connecting pipe to continue doing work. At the same time, the eleventh valve is slowly opened to increase the amount of steam entering from the middle of the low-pressure cylinder, thereby ensuring that the blades of the rear rotor in the low-pressure cylinder are cooled to prevent the exhaust temperature of the low-pressure cylinder from being too high. Finally, when the thermal power unit is operating under stable deep peak shaving conditions, the second, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth control valves are all in the open state, while the first, third, and fourth valves are all in the closed state.
[0007] The beneficial effects of this invention compared to the prior art are as follows: This invention provides a thermal control system and method for deeply adjustable output of thermal power units. Components such as the high-pressure cylinder, intermediate-pressure cylinder, low-pressure cylinder, boiler, condenser, condensate pump, low-pressure heater, deaerator, feedwater pump, third high-pressure heater, second high-pressure heater, first high-pressure heater, economizer, and denitrification system are connected via pipelines. During deep peak-shaving operation, while the turbine axial thrust is controllable, the exhaust steam temperatures of the high, medium, and low-pressure cylinders are normal, and the denitrification system is operating normally, the thermal power unit can achieve partial operation of the high-pressure cylinder, partial operation of the intermediate-pressure cylinder, and partial operation of the low-pressure cylinder, and can switch seamlessly. This results in even lower output during deep adjustment, meeting the needs of flexible unit operation. This invention can make the operation of newly built units more flexible and can also be used for the flexible retrofitting of existing units. Attached Figure Description
[0008] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the thermal control system of the present invention operating under non-deep peak shaving conditions; Figure 2 This is a schematic diagram of the thermal control system of the present invention, which adopts a deep peak-shaving operating mode. In the diagram: 1 is the high-pressure cylinder, 2 is the medium-pressure cylinder, 3 is the low-pressure cylinder, 4 is the boiler, 5 is the first valve, 6 is the second valve, 7 is the third valve, 8 is the fourth valve, 9 is the condenser, 10 is the condensate pump, 11 is the low-pressure heater, 12 is the deaerator, 13 is the feedwater pump, 14 is the third high-pressure heater, 15 is the second high-pressure heater, 16 is the first high-pressure heater, 17 is the economizer, 18 is the denitrification system, 19 is the eighth valve, 20 is the seventh valve, 21 is the sixth valve, 22 is the fifth valve, 23 is the ninth valve, 24 is the tenth valve, 25 is the eleventh valve, 26 is the twelfth valve, and 27 is the twelfth valve. Detailed Implementation
[0009] This invention addresses the technical problems of limited adjustment capability of existing thermal power units due to difficulties in controlling turbine axial thrust, excessively high exhaust temperatures in high, medium, and low pressure cylinders, and malfunctioning denitrification systems during output depth adjustment. It provides a thermodynamic control system and method for thermal power units with adjustable output depth, enabling flexible adjustment of thermal power units.
[0010] like Figure 1 and Figure 2 As shown, this invention provides a thermal power unit output control system and corresponding control method with deeply adjustable output. The control system includes a high-pressure cylinder 1, an intermediate-pressure cylinder 2, a low-pressure cylinder 3, a boiler 4, a condenser 9, a condensate pump 10, a low-pressure heater 11, a deaerator 12, a feedwater pump 13, a third high-pressure heater 14, a second high-pressure heater 15, a first high-pressure heater 16, an economizer 17, and a denitrification system 18. The steam side of the boiler 4 is connected to the inlet of the high-pressure cylinder 1 through a steam pipeline equipped with a first valve 5. The boiler 4 is also connected to the middle of the high-pressure cylinder 1 through a steam pipeline equipped with a ninth valve 23. The opening in the middle of the high-pressure cylinder 1 is located between the inlet of the high-pressure cylinder 1 and the first steam extraction port of the high-pressure cylinder 1. The steam side of the boiler 4 is connected to the inlet of the intermediate pressure cylinder 2 through a steam pipeline equipped with a third valve 7. The boiler 4 is also connected to the middle part of the intermediate pressure cylinder 2 through a steam pipeline equipped with a tenth valve 24. The opening in the middle part of the intermediate pressure cylinder 2 is located between the inlet of the intermediate pressure cylinder 2 and the third steam extraction port of the intermediate pressure cylinder 2. The high-pressure cylinder 1 is connected to the first high-pressure heater 16 through a first extraction steam pipeline equipped with a fifth valve 22 and a sixth valve 21. The high-pressure cylinder 1 is connected to the boiler 4 through a steam exhaust pipe equipped with a second valve 6; The high-pressure cylinder 1 is connected to the second high-pressure heater 15 through a second extraction steam pipeline equipped with a seventh valve 20. The intermediate pressure cylinder 2 is connected to the third high pressure heater 14 through a third extraction steam pipeline equipped with an eleventh valve 25 and an eighth valve 19. The medium-pressure cylinder 2 is connected to the deaerator 12 via a steam pipeline; The intermediate pressure cylinder 2 is connected to the deaerator 12 via the fourth extraction steam pipeline; The medium-pressure cylinder 2 is connected to the low-pressure cylinder 3 through a medium-low pressure connecting pipe equipped with a fourth valve 8; The intermediate pressure cylinder 2 is connected to the low pressure cylinder 3 via a steam pipeline and a low pressure extraction steam pipeline. The low-pressure cylinder 3 is connected to the deaerator 12 via a steam pipeline equipped with a twelfth valve 26; The low-pressure cylinder 3 is connected to the low-pressure heater 11 via a steam pipeline equipped with a thirteenth valve 27; The low-pressure cylinder 3 is also connected in sequence to the condenser 9, condensate pump 10, low-pressure heater 11, deaerator 12, feed water pump 13, third high-pressure heater 14, second high-pressure heater 15, first high-pressure heater 16, economizer 17, and boiler 4 via pipelines. The flue gas side of the boiler 4 is connected to the denitrification system 18 through the economizer 17.
[0011] like Figure 1 As shown, based on the above control system, the present invention also provides a thermal control method for deeply adjustable output of thermal power units, including a control method for thermal power units operating under non-deep peak-shaving conditions, the specific steps of which are as follows: The first valve 5, the second valve 6, the third valve 7, the fourth valve 8, the fifth valve 22, the sixth valve 21, the seventh valve 20, the eighth valve 19, and the twelfth valve 26 are all in the open state, while the ninth valve 23, the tenth valve 24, and the eleventh valve 25 are all in the closed state. Steam generated by boiler 4 enters the high-pressure cylinder 1 through the first valve 5 to do work. The exhaust steam from the high-pressure cylinder 1 enters the boiler 4 through the second valve 6 for reheating. The reheated steam enters the intermediate-pressure cylinder 2 through the third valve 7 to do work. The exhaust steam from the intermediate-pressure cylinder 2 enters the low-pressure cylinder 3 through the fourth valve 8 on the medium-low pressure connecting pipe to continue doing work. The exhaust steam from the low-pressure cylinder 3 enters the condenser 9, condenses into water, and then enters the boiler 4 through the condensate pump 10, low-pressure heater 11, deaerator 12, feedwater pump 13, third high-pressure heater 14, second high-pressure heater 15, first high-pressure heater 16, economizer 17 for further heating. The first stage of high-pressure cylinder 1 extracts steam through the first extraction steam pipeline equipped with the fifth valve 22 and the sixth valve 21 and enters the first high-pressure heater 16. The second stage of high-pressure cylinder 1 extracts steam through the second extraction steam pipeline equipped with the seventh valve 20 and enters the second high-pressure heater 15. The steam extracted from the first stage of the intermediate pressure cylinder 2 enters the third high-pressure heater 14 through the third extraction pipeline equipped with the eleventh valve 25 and the eighth valve 19. The second stage of steam extraction from the intermediate pressure cylinder 2 enters the deaerator 12 through the fourth extraction pipeline; Steam extracted from the low-pressure cylinder 3 enters the low-pressure heater 11 through the low-pressure heater extraction pipeline equipped with the thirteenth valve 27; The flue gas generated by the combustion of boiler 4 enters the denitrification system 18 through economizer 17.
[0012] like Figure 2 As shown, based on the above control system, the present invention also provides a thermal control method for deeply adjustable output of thermal power units, including a control method for thermal power units operating under deep peak-shaving conditions, the specific steps of which are as follows: The first valve 5 is gradually closed to reduce the amount of main steam entering the high-pressure cylinder 1 inlet to perform work. Slowly open the ninth valve 23 to increase the amount of main steam entering from the middle of the high-pressure cylinder 1. Mix the steam that has already done work in the high-pressure cylinder 1 with the steam that has already done work in the high-pressure cylinder 1 and continue to do work in the high-pressure cylinder 1. After the parameters are improved, part of the steam enters the first high-pressure heater 16 through the first extraction steam pipeline equipped with the fifth valve 22 and the sixth valve 21, which increases the feedwater temperature at the outlet of the high-pressure heater, reduces the heat absorption of the feedwater in the economizer 17, and keeps the flue gas temperature entering the denitrification system 18 above 300℃, thereby ensuring the normal operation of the denitrification system 18. The remaining steam continues to do work in the high-pressure cylinder 1, cooling the rear rotor blades in the high-pressure cylinder 1 while controlling the axial displacement of the steam turbine within the required range, preventing the exhaust temperature of the high-pressure cylinder 1 from being too high. After that, part of the exhaust steam from the high-pressure cylinder 1 still flows through the second extraction steam pipeline equipped with the seventh valve 20 into the second high-pressure heater 15, and most of the exhaust steam from the high-pressure cylinder 1 flows through the second valve 6 into the boiler 4 for reheating. When the unit is operating under stable peak shaving conditions, and the turbine axial displacement and high-pressure cylinder 1 exhaust temperature are normal, the first valve 5 is completely closed, and the output is regulated through the ninth valve 23. The third valve 7 is gradually closed to reduce the amount of reheat steam entering the intermediate pressure cylinder 2 inlet to perform work; Slowly open the tenth valve 24 to increase the amount of reheat steam entering from the middle of the intermediate pressure cylinder 2. Mix the reheat steam with the steam that has already done work in the intermediate pressure cylinder 2 and continue to do work in the intermediate pressure cylinder 2. Part of the mixed steam still enters the third high-pressure heater 14 through the third extraction steam pipeline equipped with the eleventh valve 25 and the eighth valve 19, and part of the mixed steam enters the deaerator 12 through the fourth extraction steam pipeline. While controlling the axial displacement of the steam turbine within the required range, the blades of the rear rotor inside the intermediate pressure cylinder 2 are cooled to prevent the exhaust temperature of the intermediate pressure cylinder 2 from being too high. When the unit is in a stable deep peak shaving condition, and the turbine axial displacement and intermediate pressure cylinder 2 exhaust temperature are normal, the third valve 7 is completely closed, and the reheat steam parameters are adjusted through the tenth valve 24. The control gradually closes the fourth valve 8 to reduce the amount of steam entering the low-pressure cylinder 3 to continue doing work through the fourth valve 8 on the medium-low pressure connecting pipe; Slowly open the eleventh valve 25 to allow some of the steam from the intermediate-pressure cylinder 2 to enter the middle of the low-pressure cylinder 3 and mix with the steam that has already done work in the low-pressure cylinder 3. Then, it will continue to do work in the low-pressure cylinder 3. At the same time, it will cool the blades of the rotor at the rear of the low-pressure cylinder 3 to prevent the steam temperature from being too high. Part of the exhaust steam from the intermediate pressure cylinder 2 enters the low-pressure heater 11 through the low-pressure heater extraction pipeline equipped with the thirteenth valve 27; When the unit is in a stable deep peak shaving condition and the exhaust temperature of the low-pressure cylinder 3 is normal, the fourth valve 8 is completely closed, and the steam parameters of the middle steam inlet of the low-pressure cylinder 3 are adjusted by controlling the eleventh valve 25. During the adjustment process, gradually close the first valve 5 to reduce the amount of main steam entering from the inlet of the high-pressure cylinder 1 to perform work, while slowly opening the ninth valve 23 to increase the amount of main steam entering from the middle of the high-pressure cylinder. Gradually close the third valve 7 to reduce the amount of reheat steam entering from the inlet of the intermediate-pressure cylinder 2 to perform work, while slowly opening the tenth valve 24 to increase the amount of reheat steam entering from the middle of the intermediate-pressure cylinder 2. The above operations need to be coordinated to control the axial displacement of the turbine within the required range. During the adjustment process, the fourth valve 8 is gradually closed to reduce the amount of steam entering the low-pressure cylinder 3 through the fourth valve 8 on the medium-low pressure connecting pipe to continue doing work. At the same time, the eleventh valve 25 is slowly opened to increase the amount of steam entering from the middle of the low-pressure cylinder 3, thereby ensuring that the blades of the rotor in the rear part of the low-pressure cylinder 3 are cooled to prevent the exhaust temperature of the low-pressure cylinder 3 from being too high. Finally, when the thermal power unit is operating under stable deep peak shaving conditions, the second valve 6, the fifth valve 22, the sixth valve 21, the seventh valve 20, the eighth valve 19, the ninth valve 23, the tenth valve 24, the eleventh valve 25, and the twelfth valve 26 are all in the open state, while the first valve 5, the third valve 7, and the fourth valve 8 are all in the closed state.
[0013] This invention proposes a thermal power unit with deeply adjustable output and control method, which can operate in three modes: high-pressure cylinder 1, intermediate-pressure cylinder 2, and low-pressure cylinder 3, and can switch without disturbance. During deep peak shaving operation, steam only performs work in the middle and later parts of high-pressure cylinder 1, intermediate-pressure cylinder 2, and low-pressure cylinder 3, shortening the work process and thus reducing the deep adjustment output of the unit, meeting the needs of flexible unit operation. By closing the first valve 5 to reduce the amount of main steam entering from the inlet of the high-pressure cylinder 1 to perform work, opening the ninth valve 23 to increase the amount of main steam entering from the middle of the high-pressure cylinder 1, closing the third valve 7 to reduce the amount of reheat steam entering from the inlet of the intermediate-pressure cylinder 2 to perform work, and opening the tenth valve 24 to increase the amount of reheat steam entering from the middle of the intermediate-pressure cylinder 2, the axial displacement of the turbine is controlled within the required range while the blades of the rear rotor in the high-pressure cylinder 1 and intermediate-pressure cylinder 2 are cooled to prevent the exhaust temperature of the high-pressure cylinder 1 and intermediate-pressure cylinder 2 from being too high. By closing the third valve 7, the amount of reheat steam entering from the inlet of the intermediate pressure cylinder 2 to perform work is reduced, and the tenth valve 24 is opened to increase the amount of reheat steam entering from the middle of the intermediate pressure cylinder 2. This controls the axial displacement of the turbine within the required range while cooling the blades of the rotor in the middle and rear of the intermediate pressure cylinder 2 to prevent the exhaust temperature of the intermediate pressure cylinder from being too high. By closing the fourth valve 8, the amount of steam entering the low-pressure cylinder 3 through the fourth valve 8 on the medium-low pressure connecting pipe is reduced to continue doing work. The eleventh valve 25 is opened to increase the amount of steam entering the middle of the low-pressure cylinder 3, thereby cooling the blades of the rear rotor inside the low-pressure cylinder 3 and preventing the exhaust temperature of the low-pressure cylinder from being too high. By opening the ninth valve 23, the high-parameter main steam entering from the middle of the high-pressure cylinder 1 is mixed with the low-parameter steam that has already done work in the high-pressure cylinder 1. This allows the steam with the increased parameters to enter the first high-pressure heater 16 through the first extraction steam pipeline equipped with the fifth valve 22. This increases the feedwater temperature at the outlet of the high-pressure heater, reduces the heat absorption of the feedwater in the economizer 17, and ensures that the flue gas temperature entering the denitrification system 18 remains above 300°C, thereby guaranteeing the normal operation of the denitrification system 18.
[0014] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A thermal control system for thermal power unit with deeply adjustable output, characterized in that: Includes a high-pressure cylinder (1), a medium-pressure cylinder (2), a low-pressure cylinder (3), a boiler (4), a condenser (9), a condensate pump (10), a low-pressure heater (11), a deaerator (12), a feedwater pump (13), a third high-pressure heater (14), a second high-pressure heater (15), a first high-pressure heater (16), an economizer (17), and a denitrification system (18), wherein: The steam side of the boiler (4) is connected to the inlet of the high-pressure cylinder (1) through a steam pipeline equipped with a first valve (5). The boiler (4) is also connected to the middle part of the high-pressure cylinder (1) through a steam pipeline equipped with a ninth valve (23). The opening position of the middle part of the high-pressure cylinder (1) is between the inlet of the high-pressure cylinder (1) and the first steam extraction port of the high-pressure cylinder (1). The steam side of the boiler (4) is connected to the inlet of the intermediate pressure cylinder (2) through a steam pipeline equipped with a third valve (7). The boiler (4) is also connected to the middle part of the intermediate pressure cylinder (2) through a steam pipeline equipped with a tenth valve (24). The opening position of the middle part of the intermediate pressure cylinder (2) is between the inlet of the intermediate pressure cylinder (2) and the third steam extraction port of the intermediate pressure cylinder (2). The high-pressure cylinder (1) is connected to the first high-pressure heater (16) through a first extraction steam pipeline equipped with a fifth valve (22) and a sixth valve (21); The high-pressure cylinder (1) is connected to the boiler (4) through a steam exhaust pipe equipped with a second valve (6); The high-pressure cylinder (1) is connected to the second high-pressure heater (15) through a second extraction steam pipeline equipped with a seventh valve (20); The intermediate pressure cylinder (2) is connected to the third high pressure heater (14) through the third extraction steam pipeline equipped with the eleventh valve (25) and the eighth valve (19); The intermediate pressure cylinder (2) is connected to the deaerator (12) via a steam pipeline; The intermediate pressure cylinder (2) is connected to the deaerator (12) through the fourth extraction steam pipeline; The medium-pressure cylinder (2) is connected to the low-pressure cylinder (3) through a medium-low pressure connecting pipe equipped with a fourth valve (8); The intermediate pressure cylinder (2) is connected to the low pressure cylinder (3) via a steam pipeline; The low-pressure cylinder (3) is connected to the deaerator (12) via a steam pipeline equipped with a twelfth valve (26); The low-pressure cylinder (3) is connected to the low-pressure heater (11) through a steam pipeline equipped with a thirteenth valve (27); The low-pressure cylinder (3) is also connected in sequence to the condenser (9), condensate pump (10), low-pressure heater (11), deaerator (12), feed water pump (13), third high-pressure heater (14), second high-pressure heater (15), first high-pressure heater (16), economizer (17), and boiler (4) via pipelines. The flue gas side of the boiler (4) is connected to the denitrification system (18) via the economizer (17).
2. The method for controlling a thermal power unit with deeply adjustable output according to claim 1, characterized in that: This includes control methods for thermal power units operating under non-deep peak-shaving conditions, with the following specific steps: Control the first valve (5), the second valve (6), the third valve (7), the fourth valve (8), the fifth valve (22), the sixth valve (21), the seventh valve (20), the eighth valve (19), and the twelfth valve (26) to be in the open state, and control the ninth valve (23), the tenth valve (24), and the eleventh valve (25) to be in the closed state; Steam generated by boiler (4) enters the high-pressure cylinder (1) through the first valve (5) to do work. The exhaust steam of the high-pressure cylinder (1) enters the boiler (4) through the second valve (6) to be reheated. The reheated steam enters the medium-pressure cylinder (2) through the third valve (7) to do work. The exhaust steam of the medium-pressure cylinder (2) enters the low-pressure cylinder (3) through the fourth valve (8) on the medium-low pressure connecting pipe to continue doing work. The exhaust steam of the low-pressure cylinder (3) enters the condenser (9) and condenses into water. After passing through the condensate pump (10), low-pressure heater (11), deaerator (12), feed water pump (13), third high-pressure heater (14), second high-pressure heater (15), first high-pressure heater (16), economizer (17), it enters the boiler (4) to continue heating. The first stage of high pressure cylinder (1) extracts steam through the first extraction steam pipeline equipped with the fifth valve (22) and the sixth valve (21) and enters the first high pressure heater (16). The second stage of the high-pressure cylinder (1) extracts steam through the second extraction pipeline equipped with the seventh valve (20) and enters the second high-pressure heater (15). The first stage of the medium pressure cylinder (2) extracts steam through the third extraction pipeline equipped with the eleventh valve (25) and the eighth valve (19) and enters the third high pressure heater (14). The second stage of the medium-pressure cylinder (2) extracts steam through the fourth extraction pipeline and enters the deaerator (12). Steam extracted from the low-pressure cylinder (3) enters the low-pressure heater (11) through the low-pressure heater extraction pipeline equipped with the thirteenth valve (27). The flue gas generated by the combustion of the boiler (4) enters the denitrification system (18) through the economizer (17).
3. The method for controlling a thermal power unit with deeply adjustable output according to claim 1, characterized in that: This includes control methods for thermal power units operating under deep peak-shaving conditions, with the following specific steps: The first valve (5) is gradually closed to reduce the amount of main steam entering the high-pressure cylinder (1) to perform work; Slowly open the ninth valve (23) to increase the amount of main steam entering from the middle of the high-pressure cylinder (1) and mix it with the steam that has already done work in the high-pressure cylinder (1) to continue doing work in the high-pressure cylinder (1); After the parameters are improved, part of the steam enters the first high-pressure heater (16) through the first extraction pipeline equipped with the fifth valve (22) and the sixth valve (21), which increases the feedwater temperature at the outlet of the high-pressure heater, reduces the heat absorption of the feedwater in the economizer (17), and ensures the normal operation of the denitrification system (18). The remaining steam continues to do work in the high-pressure cylinder (1), and while controlling the axial displacement of the steam turbine within the required range, it cools the rear rotor blades in the high-pressure cylinder (1) to prevent the exhaust temperature of the high-pressure cylinder (1) from being too high. After that, part of the exhaust steam from the high-pressure cylinder (1) still flows through the second extraction steam pipeline equipped with the seventh valve (20) into the second high-pressure heater (15), and most of the exhaust steam from the high-pressure cylinder (1) flows through the second valve (6) into the boiler (4) for reheating. When the unit is in a stable deep peak shaving condition, and the turbine axial displacement and high pressure cylinder (1) exhaust temperature are normal, the first valve (5) is completely closed, and the output is adjusted through the ninth valve (23); The third valve (7) is gradually closed to reduce the amount of reheat steam entering the inlet of the intermediate pressure cylinder (2) to perform work; Slowly open the tenth valve (24) to increase the amount of reheat steam entering from the middle of the intermediate pressure cylinder (2) and mix it with the steam that has already done work in the intermediate pressure cylinder (2) to continue doing work in the intermediate pressure cylinder (2); Part of the mixed steam still enters the third high-pressure heater (14) through the third extraction pipeline equipped with the eleventh valve (25) and the eighth valve (19), and part of the mixed steam enters the deaerator (12) through the fourth extraction pipeline. While controlling the axial displacement of the steam turbine within the required range, the blades of the rear rotor inside the intermediate pressure cylinder (2) are cooled to prevent the exhaust temperature of the intermediate pressure cylinder (2) from being too high. When the unit is in a stable deep peak shaving condition, and the turbine axial displacement and the exhaust temperature of the intermediate pressure cylinder (2) are normal, the third valve (7) is completely closed, and the reheat steam parameters are adjusted through the tenth valve (24). The control gradually closes the fourth valve (8) to reduce the amount of steam entering the low-pressure cylinder (3) to continue doing work through the fourth valve (8) on the medium-low pressure connecting pipe; Slowly open the eleventh valve (25) so that some of the steam from the intermediate pressure cylinder (2) enters the middle of the low pressure cylinder (3) and mixes with the steam that has already done work in the low pressure cylinder (3) to continue doing work in the low pressure cylinder (3). At the same time, the blades of the rotor in the rear part of the low pressure cylinder (3) are cooled to prevent the steam temperature of the low pressure cylinder (3) from being too high. The exhaust steam from part of the intermediate pressure cylinder (2) enters the low pressure heater (11) through the low pressure heater extraction pipeline equipped with the thirteenth valve (27); When the unit is in a stable deep peak shaving condition and the exhaust temperature of the low-pressure cylinder (3) is normal, the fourth valve (8) is completely closed, and the steam parameters of the middle steam inlet of the low-pressure cylinder (3) are adjusted by controlling the eleventh valve (25). During the adjustment process, the first valve (5) is gradually closed to reduce the amount of main steam entering from the inlet of the high-pressure cylinder (1) to do work, while the ninth valve (23) is slowly opened to increase the amount of main steam entering from the middle of the high-pressure cylinder. The third valve (7) is gradually closed to reduce the amount of reheat steam entering from the inlet of the intermediate-pressure cylinder (2) to do work, while the tenth valve (24) is slowly opened to increase the amount of reheat steam entering from the middle of the intermediate-pressure cylinder (2). The axial displacement of the turbine is coordinated and controlled within the required range. During the adjustment process, the fourth valve (8) is gradually closed to reduce the amount of steam entering the low-pressure cylinder (3) through the fourth valve (8) on the medium-low pressure connecting pipe to continue doing work. At the same time, the eleventh valve (25) is slowly opened to increase the amount of steam entering from the middle of the low-pressure cylinder (3), thereby ensuring that the blades of the rear rotor inside the low-pressure cylinder (3) are cooled to prevent the exhaust temperature of the low-pressure cylinder (3) from being too high. Finally, when the thermal power unit is operating under stable deep peak shaving conditions, the second valve (6), the fifth valve (22), the sixth valve (21), the seventh valve (20), the eighth valve (19), the ninth valve (23), the tenth valve (24), the eleventh valve (25), and the twelfth valve (26) are all in the open state, while the first valve (5), the third valve (7), and the fourth valve (8) are all in the closed state.