Steam turbine shaft seal and valve rod steam leakage system

Abstract

The invention belongs to the technical field of steam turbines, and particularly relates to a steam turbine shaft seal and valve rod steam leakage system. The novel electric power system is characterized in that a turboset is frequently deeply adjusted, shut down and shut down to run, valve rod leakage steam is separated from a shaft seal header, a shaft seal is free of a main steam source, only an auxiliary steam source is arranged, a high and medium pressure steam inlet end is provided with electric heating for independent temperature control, and all outmost section leakage steam is led to a shaft seal heater. Reasonable matching of the steam supply temperature of the shaft end, working medium recovery, gradient utilization of energy and no leakage under all operation conditions are achieved. The system is simplified, the arrangement is simple, the cost is low, and the system is reliable and economical.

Description

Technical Field

[0001] The invention belongs to the technical field of steam turbines, and in particular relates to a steam turbine shaft seal and valve stem steam leakage system. Background Art

[0002] Under the new power system, wind and solar power generation has gradually become the main power source, and thermal power turbines have gradually become the regulating power source. Frequent deep peak regulation, regulation, and startup have become the norm, which puts higher requirements on the shaft seal system. In order to maintain a reasonable temperature match between the shaft seal steam and each rotor, especially when the high and medium pressure cylinder units are (extremely) hot-started, the single-flow cylinder steam inlet end shaft seal requires a high steam temperature, and the high and medium pressure exhaust end requires a moderate steam temperature, so that the conventional shaft seal system cannot take into account the temperature matching of each gear at the same time. In addition, the influence of valve stem steam leakage into the shaft seal mother pipe can easily cause a large cold (hot) shock to the rotor, resulting in safety problems such as stress over-limit, deformation, cracks, locking, bending, and difficulty in turning, which seriously affects the operating reliability of the unit; at the same time, the (extremely) hot state header overflow pipeline also needs to be equipped with a cooling system to ensure the safety of subsequent components and pipelines, and the system is complex.

[0003] The new power system steam turbine is frequently adjusted, started and stopped, and in standby mode, and the valve stem operating position requirements of the unit change; the valve stem steam leakage system is generally designed according to the principle of "the unit runs at high load for a long time, the main steam valve stem does not leak steam, and only the regulating valve stem leaks steam". Generally, there are:

[0004] 1) The valve stem goes to the shaft seal manifold and the shaft seal heater one way, and the high-pressure regulating valve adds another way to go to the heat again, which can recover energy and working fluid. However, after the deep adjustment or adjustment of the unit has become the norm, the main steam and reheat steam valve stems leak a lot of steam into the shaft seal manifold, making the steam temperature in the manifold too high, aggravating the thermal shock of the high and medium pressure exhaust end of the steam turbine, causing the rotor to overheat, and causing a series of problems. At the same time, due to the difference of about 0.03MPa between the shaft seal manifold and the shaft pressure, there is little steam leakage from the shaft seal heater, and the steam introduction effect is poor, which increases the complexity of the system, the cost of piping and the difficulty of on-site layout.

[0005] 2) The valve stem of the Zhonglian gate is only directly facing the air or sewage, which causes waste of energy and working fluid. In the past, the main steam valve did not leak when the unit was under high load, and only leaked during start-up and shutdown, with few times and little impact. However, after deep adjustment or adjustment of the unit became the norm under the new power system, the unit was frequently adjusted and started and stopped, and the valve stem was in the leaking position for a long time, causing a large waste of energy and working fluid. At the same time, high-temperature leakage poses a safety hazard.

[0006] In summary, the original turbine shaft seal and valve stem steam leakage system is no longer suitable for the operation requirements of the new power system, and there are many reliability and safety issues. Summary of the invention

[0007] In order to solve the above problems existing in the prior art, the object of the present invention is to provide a turbine shaft seal and valve stem leakage system which can realize the requirements of valve stem leakage, steam introduction and shaft seal sealing under all working conditions.

[0008] The technical solution adopted by the present invention is:

[0009] A steam turbine shaft seal and valve stem leakage system, comprising a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder; further comprising a main steam valve, a main steam regulating valve, a central connection door, a shaft seal heater, a deaerator and a shaft seal header, wherein the intermediate-pressure cylinder is connected to the deaerator through a pipeline, a main steam interface is provided on the main steam valve, the main steam valve is connected to the main steam regulating valve, the main steam regulating valve is connected to the high-pressure cylinder through a pipeline, the central connection door is connected to a reheat steam pipeline, the central connection door is connected to the intermediate-pressure cylinder through a pipeline, a desuperheater is connected to the shaft seal header, a self-auxiliary steam pipeline is connected to the shaft seal header, and a condensate pipeline is connected to the desuperheater;

[0010] The main steam valve is provided with two sections of steam leakage, which are respectively connected to the deaerator and the shaft seal heater through pipelines; the main steam regulating valve is provided with three sections of steam leakage, which are respectively connected to the reheat steam pipeline, deaerator and shaft seal heater on the central door through pipelines; the main gas valve and regulating valve of the central door are both provided with one section of steam leakage, which are both connected to the shaft seal heater through pipelines;

[0011] The shaft seal at the steam inlet end of the high-pressure cylinder is provided with four sections, which are respectively connected to the reheat steam pipeline of the center door, the deaerator, the shaft seal manifold and the shaft seal heater through pipelines; the shaft seal at the exhaust end of the high-pressure cylinder is provided with three sections, which are respectively connected to the deaerator, the shaft seal manifold and the shaft seal heater through pipelines; the shaft seal at the steam inlet end of the medium-pressure cylinder is provided with two sections, which are respectively connected to the shaft seal manifold and the shaft seal heater through pipelines; the shaft seal at the exhaust end of the medium-pressure cylinder is provided with two sections, which are respectively connected to the shaft seal manifold and the shaft seal heater through pipelines; both ends of the low-pressure cylinder are provided with two sections of shaft seals, which are respectively connected to the shaft seal desuperheater and the shaft seal heater through pipelines.

[0012] Under the new power system, the steam turbine units are frequently adjusted deeply, shut down without stopping the furnace, and operate with the furnace stopped. The valve stem leakage is separated from the shaft seal manifold, the shaft seal has no main steam source, only an auxiliary steam source is provided, the high and medium pressure steam inlet ends are equipped with electric heating and independent temperature control, and all the outermost section leakage steam is led to the shaft seal heater. The shaft end steam supply temperature is reasonably matched, the working fluid is recovered, the energy is cascaded, and there is no leakage under all operating conditions. The number of leakage sections and the direction of the steam leakage are optimized to simplify the system, make the layout simple, and the cost is low. The system is reliable and economical.

[0013] As a preferred embodiment of the present invention, a main steam valve first stage steam leakage check valve is connected to the pipeline between the main steam valve and the deaerator, a main steam regulating valve second stage steam leakage check valve is connected to the pipeline between the main steam regulating valve and the deaerator, a high-pressure exhaust end first stage steam leakage check valve is connected to the pipeline between the exhaust end of the high-pressure cylinder and the deaerator, and a high-pressure inlet end second stage steam leakage check valve is connected to the pipeline between the intake end of the high-pressure cylinder and the deaerator. Steam backflow can be prevented by providing a main steam valve first stage steam leakage check valve, a main steam regulating valve second stage steam leakage check valve, a high-pressure exhaust end first stage steam leakage check valve, and a high-pressure inlet end second stage steam leakage check valve.

[0014] As a preferred solution of the present invention, a main steam regulating valve first stage steam leakage check valve is connected to the pipeline between the main steam regulating valve and the reheat steam pipeline of the center-link valve, and a high-pressure steam inlet first stage steam leakage check valve is connected to the pipeline between the air intake end of the high-pressure cylinder and the reheat steam pipeline of the center-link valve. By providing a main steam regulating valve first stage steam leakage check valve and a high-pressure steam inlet first stage steam leakage check valve, steam backflow can be prevented.

[0015] As a preferred embodiment of the present invention, a high-pressure steam inlet end electric heater and a high-pressure steam inlet end thermocouple are respectively connected to the pipeline between the air inlet end of the high-pressure cylinder and the shaft seal manifold.

[0016] As a preferred embodiment of the present invention, a medium-pressure steam inlet end electric heater and a medium-pressure steam inlet end thermocouple are respectively connected to the pipeline between the air inlet end of the medium-pressure cylinder and the shaft seal manifold.

[0017] When the steam turbine unit (extremely) is started in hot state, the temperature feedback is provided by the high-pressure steam inlet thermocouple and the medium-pressure steam inlet thermocouple. The high-pressure steam inlet electric heater and the medium-pressure steam inlet electric heater are started as needed to heat the steam sent to the high and medium-pressure shaft ends respectively. The temperature difference between the steam and each rotor is independently controlled to be matched within the design range. Since the rotor temperature difference between the air inlet end of the high-pressure cylinder and the steam inlet end of the medium-pressure cylinder is large during operation, independent temperature control and heating are required to achieve a reasonable match between the steam and the high and medium rotor temperatures.

[0018] As a preferred solution of the present invention, the shaft seal manifold is respectively connected to a pressure gauge and a manifold thermocouple.

[0019] As a preferred embodiment of the present invention, the shaft seal manifold is also connected to the condenser or the final low-temperature heater through a pipeline, an overflow valve is connected to the pipeline between the shaft seal manifold and the condenser or the final low-temperature heater, and an auxiliary steam regulating valve is connected to the auxiliary steam pipeline.

[0020] During operation, the auxiliary steam regulating valve and the relief valve opening are adjusted to maintain the pressure in the shaft seal manifold within the design range. The pressure is obtained through the pressure gauge feedback, and the steam temperature in the manifold is monitored through the manifold thermocouple. When the high and medium pressure shaft end steam leakage can meet the self-sealing pressure of the unit shaft end, the auxiliary steam regulating valve is closed, the relief valve is adjusted, and the shaft seal system enters self-sealing operation.

[0021] As a preferred solution of the present invention, a desuperheating water regulating valve is connected to the condensate pipeline, and a desuperheating thermocouple is connected to the pipeline between the desuperheater and the low-pressure cylinder. The desuperheating water regulating valve is controlled to control the steam supply temperature of the low-pressure cylinder in the desuperheater within the design range through temperature feedback of the desuperheating thermocouple.

[0022] As a preferred solution of the present invention, a first steam extraction check valve and an electric gate valve are respectively connected to the steam inlet pipeline of the deaerator.

[0023] As a preferred embodiment of the present invention, a second steam extraction check valve is connected to the pipeline between the intermediate pressure cylinder and the deaerator.

[0024] The beneficial effects of the present invention are:

[0025] Under the new power system, the steam turbine units are frequently adjusted deeply, shut down without stopping the furnace, and operate with the furnace stopped. The valve stem leakage is separated from the shaft seal manifold, the shaft seal has no main steam source, only an auxiliary steam source is provided, the high and medium pressure steam inlet ends are equipped with electric heating and independent temperature control, and all the outermost section leakage steam is led to the shaft seal heater. The shaft end steam supply temperature is reasonably matched, the working fluid is recovered, the energy is cascaded, and there is no leakage under all operating conditions. The number of leakage sections and the direction of the steam leakage are optimized to simplify the system, make the layout simple, and the cost is low. The system is reliable and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present invention.

[0027] In the figure: 1-high pressure cylinder; 2-medium pressure cylinder; 3-low pressure cylinder; 4-main steam valve; 5-main steam regulating valve; 6-intermediate valve; 7-main steam valve first stage leakage check valve; 8-main steam regulating valve first stage leakage check valve; 9-main steam regulating valve second stage leakage check valve; 10-high pressure steam inlet first stage leakage check valve; 11-high pressure exhaust first stage leakage check valve; 12-high pressure steam inlet second stage leakage check valve; 13-high pressure steam inlet End electric heater; 14-high-pressure steam inlet end thermocouple; 15-medium-pressure steam inlet end thermocouple; 16-medium-pressure steam inlet end electric heater; 17-first extraction steam check valve; 18-electric gate valve; 19-second extraction steam check valve; 20-cooling water regulating valve; 21-desuperheater; 22-cooling thermocouple; 23-auxiliary steam regulating valve; 24-pressure gauge; 25-header thermocouple; 26-shaft seal header; 27-overflow valve. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0030] like Figure 1 As shown, the steam turbine shaft seal and valve stem leakage system of this embodiment includes a high-pressure cylinder 1, an intermediate-pressure cylinder 2 and a low-pressure cylinder 3; it also includes a main steam valve 4, a main steam regulating valve 5, a central connection door 6, a shaft seal heater, a deaerator and a shaft seal header 26, the intermediate-pressure cylinder 2 is connected to the deaerator through a pipeline, the main steam valve 4 is provided with a main steam interface, the main steam valve 4 is connected to the main steam regulating valve 5, the main steam regulating valve 5 is connected to the high-pressure cylinder 1 through a pipeline, the central connection door 6 is connected to a reheat steam pipeline, the central connection door 6 is connected to the intermediate-pressure cylinder 2 through a pipeline, the shaft seal header 26 is connected to a desuperheater 21, the shaft seal header 26 is connected to an auxiliary steam pipeline, and the desuperheater 21 is connected to a condensate pipeline;

[0031] The main steam valve 4 is provided with two sections of steam leakage, which are respectively connected to the deaerator and the shaft seal heater through pipelines; the main steam regulating valve 5 is provided with three sections of steam leakage, which are respectively connected to the reheat steam pipeline, the deaerator and the shaft seal heater on the central door 6 through pipelines; the main gas valve and the regulating valve of the central door 6 are both provided with one section of steam leakage, which are both connected to the shaft seal heater through pipelines;

[0032] The steam inlet end shaft seal of the high-pressure cylinder 1 is provided with four sections, which are respectively connected to the reheat steam pipeline of the center door 6, the deaerator, the shaft seal manifold 26 and the shaft seal heater through pipelines; the exhaust end shaft seal of the high-pressure cylinder 1 is provided with three sections, which are respectively connected to the deaerator, the shaft seal manifold 26 and the shaft seal heater through pipelines; the steam inlet end shaft seal of the intermediate-pressure cylinder 2 is provided with two sections, which are respectively connected to the shaft seal manifold 26 and the shaft seal heater through pipelines; the exhaust end shaft seal of the intermediate-pressure cylinder 2 is provided with two sections, which are respectively connected to the shaft seal manifold 26 and the shaft seal heater through pipelines; both ends of the low-pressure cylinder 3 are provided with two sections of shaft seals, which are respectively connected to the shaft seal desuperheater 21 and the shaft seal heater through pipelines.

[0033] In order to prevent steam backflow, check valves are provided before the central valve 6 and on the steam leakage pipeline of the deaerator. The pipeline between the main steam valve 4 and the deaerator is connected with a main steam valve first-stage steam leakage check valve 7, the pipeline between the main steam regulating valve 5 and the deaerator is connected with a main steam regulating valve second-stage steam leakage check valve 9, the pipeline between the exhaust end of the high-pressure cylinder 1 and the deaerator is connected with a high-pressure exhaust end first-stage steam leakage check valve 11, and the pipeline between the intake end of the high-pressure cylinder 1 and the deaerator is connected with a high-pressure inlet end second-stage steam leakage check valve 12. By providing the main steam valve first-stage steam leakage check valve 7, the main steam regulating valve second-stage steam leakage check valve 9, the high-pressure exhaust end first-stage steam leakage check valve 11 and the high-pressure inlet end second-stage steam leakage check valve 12, steam backflow can be prevented.

[0034] A main steam regulating valve first stage steam leakage check valve 8 is connected to the pipeline between the main steam regulating valve 5 and the reheat steam pipeline of the central connection valve 6, and a high-pressure steam inlet first stage steam leakage check valve 10 is connected to the pipeline between the air intake end of the high-pressure cylinder 1 and the reheat steam pipeline of the central connection valve 6. By providing the main steam regulating valve first stage steam leakage check valve 8 and the high-pressure steam inlet first stage steam leakage check valve 10, steam backflow can be prevented.

[0035] Furthermore, the pipeline between the air inlet end of the high-pressure cylinder 1 and the shaft seal header 26 is respectively connected with a high-pressure steam inlet end electric heater 13 and a high-pressure steam inlet end thermocouple 14. The pipeline between the air inlet end of the medium-pressure cylinder 2 and the shaft seal header 26 is respectively connected with a medium-pressure steam inlet end electric heater 16 and a medium-pressure steam inlet end thermocouple 15. When the steam turbine unit (pole) is hot-started, the temperature feedback of the high-pressure steam inlet end thermocouple 14 and the medium-pressure steam inlet end thermocouple 15 is used to start the high-pressure steam inlet end electric heater 13 and the medium-pressure steam inlet end electric heater 16 as needed to heat the steam sent to the high and medium-pressure shaft ends respectively, and independently control the temperature difference between the steam and each rotor to match within the design range. Because the rotor temperature difference between the air inlet end of the high-pressure cylinder 1 and the steam inlet end of the medium-pressure cylinder 2 is large when running, independent temperature control and heating are required to achieve reasonable matching between the steam and the high and medium rotor temperatures.

[0036] Furthermore, the shaft seal manifold 26 is also connected to the condenser or the final low-temperature heater through a pipeline. The pipeline between the shaft seal manifold 26 and the condenser or the final low-temperature heater is connected with a relief valve 27, and the auxiliary steam regulating valve 23 is connected to the auxiliary steam pipeline. The shaft seal manifold 26 is respectively connected with a pressure gauge 24 and a manifold thermocouple 25. During operation, the pressure in the shaft seal manifold 26 is maintained within the design range by adjusting the opening of the auxiliary steam regulating valve 23 and the relief valve 27. The pressure is obtained through feedback from the pressure gauge 24, and the steam temperature in the manifold is monitored by the manifold thermocouple 25. When the high and medium pressure shaft end steam leakage can meet the self-sealing pressure of the unit shaft end, the auxiliary steam regulating valve 23 is closed, the relief valve 27 is adjusted, and the shaft seal system enters self-sealing operation.

[0037] Furthermore, a desuperheating water regulating valve 20 is connected to the condensate water pipeline, and a desuperheating thermocouple 22 is connected to the pipeline between the desuperheater 21 and the low-pressure cylinder 3. Through the temperature feedback of the desuperheating thermocouple 22, the desuperheating water regulating valve 20 is controlled in the desuperheater 21 to control the steam supply temperature of the low-pressure cylinder 3 within the design range.

[0038] The steam inlet pipeline of the deaerator is respectively connected with a first steam extraction check valve 17 and an electric gate valve 18. The pipeline between the intermediate pressure cylinder 2 and the deaerator is connected with a second steam extraction check valve 19.

[0039] Under the new power system, the steam turbine unit is frequently adjusted deeply, shut down without stopping the furnace, and operated with the furnace stopped. The valve stem leakage is separated from the shaft seal manifold 26, the shaft seal has no main steam source, only an auxiliary steam source is provided, the high and medium pressure steam inlet ends are equipped with electric heating and independent temperature control, and all the outermost section leakage steam is led to the shaft seal heater. The shaft end steam supply temperature is reasonably matched, the working fluid is recovered, the energy is cascaded, and there is no leakage under all operating conditions; the number of leakage sections and the direction of the steam leakage are optimized to simplify the system, make the layout simple, and the cost is low. The system is reliable and economical.

[0040] The control of shutdown and furnace stopping, shutdown without furnace stopping, deep adjustment and high load operation is as follows:

[0041] 1) The main steam valve 4 stem first stage steam leakage and the main steam regulating valve 5 cylinder first stage and second stage steam leakage pipelines are equipped with one-way flow mechanical check valves (main steam valve first stage steam leakage check valve 7, main steam regulating valve first stage steam leakage check valve 8, main steam regulating valve second stage steam leakage check valve 9), which can prevent steam backflow and realize self-operation without additional control.

[0042] 2) The first and second steam leakage pipes at the steam inlet shaft end and the first steam leakage pipe at the exhaust shaft end of the high-pressure cylinder 1 are all equipped with one-way flow mechanical check valves (the first steam leakage check valve 11 at the high-pressure exhaust end and the second steam leakage check valve 12 at the high-pressure steam inlet end) to prevent steam backflow and realize self-operation without the need for additional control.

[0043] 3) The steam leakage at the outermost sections of the high-pressure cylinder 1, the medium-pressure cylinder 2, the low-pressure cylinder 3, the main steam valve 4, the main steam regulating valve 5 and the central door 6 are all equipped with steam-gas mixture outlet pipelines, which are combined and then led to the shaft seal heater. No additional control is required during operation, which can prevent steam leakage at the end.

[0044] 4) During operation, the opening of the auxiliary steam regulating valve 23 and the relief valve 27 are adjusted to maintain the pressure in the shaft seal manifold 26 within the design range. The pressure is obtained through feedback from the pressure gauge 24, and the steam temperature in the box is monitored through the manifold thermocouple 25. When the high and medium pressure shaft end steam leakage can meet the self-sealing pressure of the unit shaft end, the auxiliary steam regulating valve 23 is closed, the relief valve 27 is adjusted, and the shaft seal system enters self-sealing operation.

[0045] 5) When the steam turbine unit (extremely) is started in hot state, the temperature feedback is obtained through the high-pressure steam inlet thermocouple 14 and the medium-pressure steam inlet thermocouple 15, and the high-pressure steam inlet electric heater 13 and the medium-pressure steam inlet electric heater 16 are started as needed to heat the steam sent to the high and medium-pressure shaft ends respectively, and the temperature difference between the steam and each rotor is independently controlled to match within the design range. Since the rotor temperature difference between the air inlet end of the high-pressure cylinder 1 and the steam inlet end of the medium-pressure cylinder 2 is relatively large during operation, independent temperature control and heating are required to achieve reasonable matching of the steam temperature with the high and medium rotors.

[0046] 6) Through the temperature feedback of the desuperheating thermocouple 22, the desuperheating water regulating valve 20 is controlled in the desuperheater 21 to control the steam supply temperature of the low-pressure cylinder 3 within the design range.

[0047] The present invention realizes the requirements of valve stem leakage, steam introduction and shaft seal sealing under all working conditions through system optimization. At the same time, the steam supply temperature of each shaft end is reasonably matched with the rotor, the thermal shock is small, the working medium is recovered, the energy is utilized in a cascade manner, there is no steam leakage, the system safety is simplified, the layout is simple and the cost is low.

[0048] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A steam turbine shaft seal and valve stem steam leakage system, comprising a high-pressure cylinder (1), a medium-pressure cylinder (2) and a low-pressure cylinder (3); characterized in that: It also includes a main steam valve (4), a main steam regulating valve (5), a central connection door (6), a shaft seal heater, a deaerator and a shaft seal header (26); the intermediate pressure cylinder (2) is connected to the deaerator via a pipeline; the main steam valve (4) is provided with a main steam interface; the main steam valve (4) is connected to the main steam regulating valve (5); the main steam regulating valve (5) is connected to the high pressure cylinder (1) via a pipeline; the central connection door (6) is connected to a reheat steam pipeline; the central connection door (6) is connected to the intermediate pressure cylinder (2) via a pipeline; the shaft seal header (26) is connected to a desuperheater (21); the shaft seal header (26) is connected to an auxiliary steam pipeline; and the desuperheater (21) is connected to a condensate pipeline; The main steam valve (4) is provided with two sections of steam leakage, which are respectively connected to the deaerator and the shaft seal heater through pipelines; the main steam regulating valve (5) is provided with three sections of steam leakage, which are respectively connected to the reheat steam pipeline, the deaerator and the shaft seal heater on the central door (6) through pipelines; the main steam valve and the regulating valve of the central door (6) are both provided with one section of steam leakage, which are both connected to the shaft seal heater through pipelines; The shaft seal at the steam inlet end of the high-pressure cylinder (1) is provided with four sections, which are respectively connected to the reheat steam pipeline of the center valve (6), the deaerator, the shaft seal manifold (26) and the shaft seal heater through pipelines; the shaft seal at the steam exhaust end of the high-pressure cylinder (1) is provided with three sections, which are respectively connected to the deaerator, the shaft seal manifold (26) and the shaft seal heater through pipelines; the shaft seal at the steam inlet end of the medium-pressure cylinder (2) is provided with two sections, which are respectively connected to the shaft seal manifold (26) and the shaft seal heater through pipelines; the shaft seal at the steam exhaust end of the medium-pressure cylinder (2) is provided with two sections, which are respectively connected to the shaft seal manifold (26) and the shaft seal heater through pipelines; both ends of the low-pressure cylinder (3) have two sections of shaft seals, which are respectively connected to the shaft seal desuperheater (21) and the shaft seal heater through pipelines.

2. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: A main steam valve first-stage steam leakage check valve (7) is connected to the pipeline between the main steam valve (4) and the deaerator, a main steam regulating valve second-stage steam leakage check valve (9) is connected to the pipeline between the main steam regulating valve (5) and the deaerator, a high-pressure exhaust end first-stage steam leakage check valve (11) is connected to the pipeline between the exhaust end of the high-pressure cylinder (1) and the deaerator, and a high-pressure inlet end second-stage steam leakage check valve (12) is connected to the pipeline between the intake end of the high-pressure cylinder (1) and the deaerator.

3. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: A main steam regulating valve first stage steam leakage check valve (8) is connected to the pipeline between the main steam regulating valve (5) and the reheat steam pipeline of the center valve (6), and a high-pressure steam inlet end first stage steam leakage check valve (10) is connected to the pipeline between the air intake end of the high-pressure cylinder (1) and the reheat steam pipeline of the center valve (6).

4. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: A high-pressure steam inlet end electric heater (13) and a high-pressure steam inlet end thermocouple (14) are respectively connected to the pipeline between the air inlet end of the high-pressure cylinder (1) and the shaft seal header (26).

5. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: A medium-pressure steam inlet end electric heater (16) and a medium-pressure steam inlet end thermocouple (15) are respectively connected to the pipeline between the air inlet end of the medium-pressure cylinder (2) and the shaft seal manifold (26).

6. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: The shaft seal manifold (26) is respectively connected to a pressure gauge (24) and a manifold thermocouple (25).

7. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: The shaft seal header (26) is also connected to the condenser or the final low-temperature heater via a pipeline; a relief valve (27) is connected to the pipeline between the shaft seal header (26) and the condenser or the final low-temperature heater; and an auxiliary steam regulating valve (23) is connected to the auxiliary steam pipeline.

8. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: The condensate water pipeline is connected to a cooling water regulating valve (20), and the pipeline between the cooler (21) and the low-pressure cylinder (3) is connected to a cooling thermocouple (22).

9. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: The steam inlet pipeline of the deaerator is respectively connected to a first steam extraction check valve (17) and an electric gate valve (18).

10. A steam turbine shaft seal and valve stem steam leakage system according to claim 1, characterized in that: A second steam extraction check valve (19) is connected to the pipeline between the intermediate pressure cylinder (2) and the deaerator.

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