Steam turbine system for deep peak regulation low-pressure cylinder efficiency improvement and operation method

Abstract

The invention discloses a steam turbine system for efficiency improvement of a deep peak regulation low-pressure cylinder and an operation method, relates to the field of power plants, and is mainly used for solving the problem that the heat consumption rate of the power plants is obviously increased in the deep peak regulation process. The system mainly comprises a low-pressure cylinder, a hydraulic control butterfly valve, a cooler, a control valve, a generator and the like. An original communicating pipe between the low-pressure cylinders is replaced with the hydraulic control butterfly valve which can be completely closed and has zero leakage, steam inlet of the low-pressure cylinder on one side is cut off during low load, all steam enters the low-pressure cylinder on the other side to do work, and the effect that a steam turbine unit efficiently operates during low load is achieved. According to the invention, the problems of low efficiency in the low-pressure cylinder and poor thermal economy of the turboset caused by reduction of the steam flow when the turboset is in a low load can be reduced, and the peak regulation performance of the turboset is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of steam turbines in power plants, and in particular to a steam turbine system and an operating method for deep peak regulation and low-pressure cylinder efficiency improvement. Background Art

[0002] With the rapid development of renewable energy generation technology, the proportion of renewable energy generation continues to rise. Among these, the highly developed solar and wind power generation are characterized by intermittent and fluctuating characteristics, necessitating peak-shaving by power plants to improve grid stability. However, during deep peak-shaving, as the power generation load continues to decrease, the steam flow rate decreases, leading to a rapid decrease in the relative internal efficiency of the turbine's low-pressure cylinder, reducing the system's thermal economy. Furthermore, during ultra-low-load operation, the turbine's final low-pressure cylinder can experience safety issues such as blade airflow vibration, blade blasting, dynamic and static friction, and blade erosion, increasing losses and further reducing low-pressure cylinder efficiency. Therefore, in the context of deep peak-shaving, improving the efficiency of the turbine's low-pressure cylinder is a crucial aspect of improving the unit's thermal economy. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a steam turbine system and operation method for deep peak regulation to improve the efficiency of low-pressure cylinders. By replacing the original connecting pipes between the low-pressure cylinders with a hydraulically controlled butterfly valve that can be 100% closed and has zero leakage, the steam supply to the low-pressure cylinder on one side is cut off at low load, and all the steam enters the low-pressure cylinder on the other side to perform work, thereby improving the efficiency of the low-pressure cylinder at low load.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A steam turbine system for deep peak regulation includes a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder A4, a low-pressure cylinder B5, a generator 6, a condenser 7, a condensate pump 8, a low-pressure heater group 9, a deaerator 10, a feedwater pump 11, a high-pressure heater 12, a high-pressure heater group 13, a hydraulically controlled butterfly valve 14, a cooler 15, a control valve 16, and a low-pressure heater steam inlet valve 17;

[0006] The main steam outlet of the boiler 1 is connected to the steam inlet of the high-pressure cylinder 2, the steam outlet of the high-pressure cylinder 2 is connected to the reheat steam inlet of the boiler 1, the reheat steam outlet of the boiler 1 is connected to the steam inlet of the intermediate-pressure cylinder 3, the steam outlet of the intermediate-pressure cylinder 3 is connected to the steam inlet of the low-pressure cylinder A4 and the low-pressure cylinder B5, the steam outlet of the low-pressure cylinder A4 and the low-pressure cylinder B5 is connected to the inlet of the condenser 7, the shafts of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, the low-pressure cylinder A4 and the low-pressure cylinder B5 are connected to the generator 6, the outlet of the condenser 7 is connected to the water inlet of the low-pressure heater group 9 through the condensate pump 8, and the water outlet of the low-pressure heater group 9 is connected to the water inlet of the deaerator 10. The feed water outlet of the deaerator 10 is connected to the feed water inlet of the high-pressure heater 12 through the feed water pump 11, the feed water outlet of the high-pressure heater 12 is connected to the feed water inlet of the high-pressure heater group 13, and the feed water outlet of the high-pressure heater group 13 is connected to the feed water inlet of the boiler 1; the steam inlet of the low-pressure heater group 9 is respectively connected to the low-pressure cylinder A4 and the extraction steam outlet of the low-pressure cylinder B5 through the low-pressure heater steam inlet valve 17, the steam inlet of the deaerator 10 is connected to the steam outlet of the intermediate-pressure cylinder 3, the steam inlet of the high-pressure heater 12 is connected to the extraction steam outlet of the intermediate-pressure cylinder 3, and the steam inlet of the high-pressure heater group 13 is connected to the extraction steam outlet of the high-pressure cylinder 2;

[0007] In the steam turbine system for deep peak regulation and improving the efficiency of the low-pressure cylinder, the original connecting pipe between the low-pressure cylinders is converted into a hydraulically controlled butterfly valve that can be 100% closed and has zero leakage. The low-pressure cylinder A4 is connected to the low-pressure cylinder B5 through the hydraulically controlled butterfly valve 14, and a cooling steam bypass is added between the intermediate-pressure cylinder 3 and the low-pressure cylinder B5. A cooler 15 and a control valve 16 are provided on the cooling steam bypass.

[0008] The operating method of the steam turbine system for deep peak regulation and low-pressure cylinder efficiency improvement is as follows: when the load of the steam turbine unit is higher than 30%, the hydraulically controlled butterfly valve 14 and the low-pressure heater steam inlet valve 17 are opened, and the cooler 15 and the control valve 16 are closed to achieve normal operation of the four-cylinder four-exhaust steam turbine unit;

[0009] The operating method of the steam turbine system for deep peak regulation and improving the efficiency of the low-pressure cylinder is as follows: when the load of the steam turbine unit is lower than 30%, the hydraulically controlled butterfly valve 14 and the low-pressure heater steam inlet valve 17 are closed, so that the steam inlet to the low-pressure cylinder B5 is completely closed, and all the steam at the low-pressure cylinder inlet enters the low-pressure cylinder A4 to perform work. At the same time, the cooler 15 and the control valve 16 are opened to ensure that a small amount of cooling steam enters the low-pressure cylinder B5 to take away the blast heat generated by the rotation of the rotor.

[0010] Preferably, after the cooler 15 and the control valve 16 are opened, the flow rate of the cooling steam introduced is 10% to 15% of the steam flow rate at the outlet of the intermediate pressure cylinder, which can effectively absorb the heat generated by the blast effect of the low pressure cylinder rotor.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] (1) During deep peak regulation, the steam inlet to the low-pressure cylinder on one side is cut off, allowing all steam to enter the low-pressure cylinder on the other side to perform work, which significantly improves the relative internal efficiency of the low-pressure cylinder on one side and improves thermal economy.

[0013] (2) During low-load operation, a small amount of cooling steam is introduced into the removed low-pressure cylinder, reducing the damage to the low-pressure cylinder blades caused by the blast effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a system diagram of the present invention.

[0015] Among them, 1. Boiler, 2. High-pressure cylinder, 3. Medium-pressure cylinder, 4. Low-pressure cylinder A, 5. Low-pressure cylinder B, 6. Generator, 7. Condensate pump, 8. Condensate pump, 9. Low-pressure heater group, 10. Deaerator, 11. Feed water pump, 12. High-pressure heater, 13. High-pressure heater group, 14. Hydraulic-controlled butterfly valve, 15. Cooler, 16. Control valve, 17. Low-pressure heater steam inlet valve. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 As shown, the present invention provides a steam turbine system for deep peak regulation and low-pressure cylinder efficiency improvement, including a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder A4, a low-pressure cylinder B5, a generator 6, a condenser 7, a condensate pump 8, a low-pressure heater group 9, a deaerator 10, a feed water pump 11, a high-temperature heater 12, a high-temperature heater group 13, a hydraulically controlled butterfly valve 14, a cooler 15, a control valve 16, and a low-pressure heater steam inlet valve 17.

[0018] The main steam outlet of the boiler 1 is connected to the steam inlet of the high-pressure cylinder 2, the steam outlet of the high-pressure cylinder 2 is connected to the reheat steam inlet of the boiler 1, the reheat steam outlet of the boiler 1 is connected to the steam inlet of the intermediate-pressure cylinder 3, the steam outlet of the intermediate-pressure cylinder 3 is connected to the steam inlet of the low-pressure cylinder A4 and the low-pressure cylinder B5, the steam outlet of the low-pressure cylinder A4 and the low-pressure cylinder B5 is connected to the inlet of the condenser 7, the shafts of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, the low-pressure cylinder A4 and the low-pressure cylinder B5 are connected to the generator 6, the outlet of the condenser 7 is connected to the water inlet of the low-pressure heater group 9 through the condensate pump 8, and the water outlet of the low-pressure heater group 9 is connected to the water inlet of the deaerator 10. The feed water outlet of the deaerator 10 is connected to the feed water inlet of the high-pressure heater 12 through the feed water pump 11, the feed water outlet of the high-pressure heater 12 is connected to the feed water inlet of the high-pressure heater group 13, and the feed water outlet of the high-pressure heater group 13 is connected to the feed water inlet of the boiler 1; the steam inlet of the low-pressure heater group 9 is respectively connected to the low-pressure cylinder A4 and the extraction steam outlet of the low-pressure cylinder B5 through the low-pressure heater steam inlet valve 17, the steam inlet of the deaerator 10 is connected to the steam outlet of the intermediate-pressure cylinder 3, the steam inlet of the high-pressure heater 12 is connected to the extraction steam outlet of the intermediate-pressure cylinder 3, and the steam inlet of the high-pressure heater group 13 is connected to the extraction steam outlet of the high-pressure cylinder 2;

[0019] The low-pressure cylinder A4 is connected to the low-pressure cylinder B5 through a hydraulically controlled butterfly valve 14 , and the cooling steam bypass between the medium-pressure cylinder 3 and the low-pressure cylinder B5 is connected through a cooler 15 and a control valve 16 .

[0020] The operating method of a steam turbine system for deep peak regulation and improving the efficiency of the low-pressure cylinder is as follows: when the load of the steam turbine unit is higher than 30%, the relative internal efficiency of the low-pressure cylinder is relatively high, and there is no need to cut off the steam inlet to the low-pressure cylinder on one side, so that all the steam enters the low-pressure cylinder on one side to perform work. Therefore, the hydraulically controlled butterfly valve 14 and the low-pressure heater steam inlet valve 17 are opened, and the cooler 15 and the control valve 16 are closed to achieve normal operation of the four-cylinder four-exhaust steam turbine unit; when the load of the steam turbine unit is lower than 30%, the steam flow entering the low-pressure cylinder A4 and the low-pressure cylinder B5 is significantly reduced, and the relative internal efficiency of the low-pressure cylinder decreases rapidly. At this time, the hydraulically controlled butterfly valve 14 and the low-pressure heater steam inlet valve 17 can be closed. The steam inlet of the low-pressure cylinder B5 is completely closed, and all the steam at the low-pressure cylinder inlet enters the low-pressure cylinder A4 to perform work, so as to improve the efficiency of the single-side low-pressure cylinder. At the same time, the cooler 15 and the control valve 16 are opened, and a small amount of cooling steam is cooled and decompressed and then passed into the low-pressure cylinder B5 to take away the blast heat generated by the rotation of the rotor. At this time, the low-pressure cylinder B5 does not perform work and the output is zero. The low-pressure rotor only plays the role of transmitting torque. At the same time, under low-load operation, the safety problems that may occur in the last-stage blades of the low-pressure cylinder, such as blade airflow vibration, blade blasting, dynamic and static friction, and blade water erosion, are also effectively suppressed, thereby reducing the resulting losses and extending the life of the low-pressure cylinder blades.

[0021] By using the system and method of the present invention, the steam inlet flow rate of the single-side low-pressure cylinder can be increased, the relative internal efficiency of the low-pressure cylinder can be significantly improved, and the efficient operation of the steam turbine unit at low load can be achieved; the present invention can reduce the problem of low relative internal efficiency of the low-pressure cylinder and poor thermal economy of the steam turbine unit due to the reduction of steam flow at low load, thereby improving the peak-shaving performance of the steam turbine unit.

Claims

1. A steam turbine system for deep peak regulation and low-pressure cylinder efficiency improvement, characterized in that: The invention comprises a boiler (1), a high-pressure cylinder (2), an intermediate-pressure cylinder (3), a low-pressure cylinder A (4), a low-pressure cylinder B (5), a generator (6), a condenser (7), a condensate pump (8), a low-pressure heater group (9), a deaerator (10), a feedwater pump (11), a high-pressure heater (12), a high-pressure heater group (13), a hydraulically controlled butterfly valve (14), a cooler (15), a control valve (16) and a low-pressure heater steam inlet valve (17); the main steam outlet of the boiler (1) is connected to the steam inlet of the high-pressure cylinder (2), and the steam outlet of the high-pressure cylinder (2) is connected to the boiler (1). The reheat steam inlet of the furnace (1) is connected, the reheat steam outlet of the boiler (1) is connected to the steam inlet of the medium pressure cylinder (3), the steam outlet of the medium pressure cylinder (3) is connected to the steam inlet of the low pressure cylinder A (4) and the low pressure cylinder B (5), the steam outlet of the low pressure cylinder A (4) and the low pressure cylinder B (5) is connected to the inlet of the condenser (7), the shafts of the high pressure cylinder (2), the medium pressure cylinder (3), the low pressure cylinder A (4) and the low pressure cylinder B (5) are connected to the generator (6), and the outlet of the condenser (7) is connected to the outlet of the low pressure heater group (9) through the condensate pump (8). The water inlet of the low-pressure heater group (9) is connected to the water inlet of the deaerator (10), the water outlet of the deaerator (10) is connected to the water inlet of the high-pressure heater (12) through the water feed pump (11), the water outlet of the high-pressure heater (12) is connected to the water inlet of the high-pressure heater group (13), and the water outlet of the high-pressure heater group (13) is connected to the water inlet of the boiler (1); the steam inlet of the low-pressure heater group (9) is respectively connected to the low-pressure cylinder A (4) and the low-pressure cylinder A (5) through the low-pressure heater steam inlet valve (17). The steam inlet of the deaerator (10) is connected to the steam outlet of the medium-pressure cylinder (3), the steam inlet of the high-pressure heater (12) is connected to the steam outlet of the medium-pressure cylinder (3), and the steam inlet of the high-pressure heater group (13) is connected to the steam outlet of the high-pressure cylinder (2); the low-pressure cylinder A (4) is connected to the low-pressure cylinder B (5) through a hydraulically controlled butterfly valve (14), and a cooling steam bypass is added between the medium-pressure cylinder (3) and the low-pressure cylinder B (5), and a cooler (15) and a control valve (16) are provided on the cooling steam bypass.

2. The method for operating a steam turbine system for deep peak regulation and improving the efficiency of low-pressure cylinders according to claim 1, characterized in that: When the load of the steam turbine unit is higher than 30%, the hydraulically controlled butterfly valve (14) and the low-pressure heater steam inlet valve (17) are opened, and the cooler (15) and the control valve (16) are closed to achieve normal operation of the four-cylinder four-exhaust steam turbine unit; When the load of the steam turbine unit is lower than 30%, the hydraulically controlled butterfly valve (14) and the low-pressure heater steam inlet valve (17) are closed, so that the steam inlet of the low-pressure cylinder B (5) is completely closed, and all the steam at the low-pressure cylinder inlet enters the low-pressure cylinder A (4) to perform work. At the same time, the cooler (15) and the control valve (16) are opened to ensure that a small amount of cooling steam enters the low-pressure cylinder B (5) to take away the blast heat generated by the rotation of the rotor.

3. The method for operating a steam turbine system for deep peak regulation and improving the efficiency of low-pressure cylinders according to claim 2, characterized in that: After the cooler (15) and the control valve (16) are opened, the flow rate of the cooling steam introduced is 10% to 15% of the steam flow rate at the outlet of the medium pressure cylinder.

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