A shaft seal hot standby operation system and method of operation

Abstract

The present application relates to a kind of shaft seal hot backup operation system and operation method, system includes auxiliary steam hot backup subsystem, steam turbine, condenser and low pressure heater, steam turbine is connected with shaft seal steam supply main pipe;The steam outlet of auxiliary steam hot backup subsystem is respectively connected with shaft seal steam supply main pipe, condenser and low pressure heater with shaft seal auxiliary steam pipe, first drain pipe and second drain pipe;Shaft seal auxiliary steam pipe, first drain pipe and second drain pipe are respectively communicated with shaft seal regulating valve, first drain electric door and second drain electric door.The present application can effectively guarantee shaft seal hot backup steam temperature, while recovering shaft seal hot backup steam source drain to low pressure heater, improve unit safety and economy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steam turbine shaft seal, in particular to a shaft seal hot standby operation system and operation method. BACKGROUND

[0002] The shaft seal system is to prevent steam from leaking along the high and medium pressure cylinder shaft end from inside to outside, even into the bearing box to make the lubricating oil into water or air from outside to inside, and to reduce the heat loss and improve the environmental conditions of the steam turbine plant.

[0003] The shaft seal system is generally a self-sealing system, which means that when the unit is running normally, the steam leakage from the high pressure cylinder shaft end is used as steam supply for the low pressure cylinder shaft end after passing through the medium pressure cylinder, and the excess steam is overflowed to the condenser through the overflow station. During or at low load operation stage, the steam seal supply is provided by the auxiliary steam header through the shaft seal auxiliary steam main pipe, which serves as a standby system.

[0004] However, since the shaft seal auxiliary steam main pipe supply is in a hot standby stage during the self-sealing stage of the unit, steam does not flow, and the generated drain water will accumulate and reduce the temperature of the auxiliary steam, which needs to be drained to the condenser regularly. In order to ensure the temperature of the auxiliary steam, heating or mixing high temperature steam is needed to increase the temperature of the hot standby shaft seal auxiliary steam, and then the auxiliary steam with increased temperature will enter the condenser together with the drain water, which not only wastes the auxiliary steam of the unit, but also increases the heat load of the condenser, which is not conducive to the economy of the unit. Therefore, the present application provides a shaft seal hot standby operation system and operation method to solve the above problems. SUMMARY

[0005] The present application provides a shaft seal hot standby operation system and operation method, which can effectively ensure the temperature of the hot standby steam and improve the safety of the steam turbine shaft seal.

[0006] To achieve the above object, the present application adopts the following technical scheme:

[0007] A shaft seal hot standby operation system, comprising an auxiliary steam hot standby subsystem, a steam turbine, a condenser and a low pressure heater, wherein the steam turbine is connected with a shaft seal steam supply main pipe;

[0008] The outlet of the auxiliary steam hot standby subsystem is connected with a shaft seal auxiliary steam pipe, a first drain pipe and a second drain pipe through the shaft seal steam supply main pipe, the condenser and the low pressure heater, respectively;

[0009] The shaft seal auxiliary steam pipe, the first drain pipe and the second drain pipe are respectively connected with a shaft seal regulating valve, a first drain electric door and a second drain electric door.

[0010] Preferably, the auxiliary steam hot standby subsystem comprises an auxiliary steam header, a heating device and a temperature measuring device.

[0011] The steam outlet of the auxiliary steam header is communicated with a shaft seal auxiliary steam main pipe, the shaft seal auxiliary steam main pipe is connected with a heating pipe, and the heating device is installed on the heating pipe;

[0012] The temperature measuring device is arranged at the connection between the shaft seal auxiliary steam main pipe and the shaft seal auxiliary steam pipe, used for measuring the temperature of the auxiliary steam, and used in cooperation with the heating device.

[0013] Preferably, the shaft seal auxiliary steam main pipe comprises a first auxiliary steam main pipe, an auxiliary steam supply pipe and a second auxiliary steam main pipe, the auxiliary steam supply pipe is connected with the heating pipe in parallel, and the second auxiliary steam main pipe is communicated with the shaft seal auxiliary steam pipe, the first drain pipe and the second drain pipe;

[0014] The first auxiliary steam main pipe is provided with an auxiliary steam to shaft seal supply electric door, and the auxiliary steam supply pipe is provided with a shaft seal supply electric door.

[0015] Preferably, a check valve is arranged on the second drain pipe between the second drain electric door and the low-pressure heater.

[0016] A running method of the shaft seal hot standby system, comprising:

[0017] Before the unit is started, the first drain electric door is opened, the shaft seal adjusting valve and the second drain electric door are closed, and the auxiliary steam in the auxiliary steam hot standby subsystem enters the condenser through the first drain pipe, until the unit is started;

[0018] When the unit is started and the shaft seal system is self-sealed or in a low load stage, the shaft seal adjusting valve is opened, the first drain electric door and the second drain electric door are closed, and the auxiliary steam in the auxiliary steam hot standby subsystem and the drain water enter the shaft seal supply main pipe through the shaft seal auxiliary steam pipe, so as to seal the steam turbine;

[0019] When the unit is in a certain load and the shaft seal system is self-sealed, the second drain electric door is opened, the shaft seal adjusting valve and the first drain electric door are closed, and the auxiliary steam in the auxiliary steam hot standby subsystem enters the low-pressure heater through the second drain pipe, so as to maintain the continuous flow of the auxiliary steam.

[0020] Preferably, when the unit is in an emergency shutdown, the shaft seal adjusting valve is opened, the first drain electric door and the second drain electric door are closed, and the auxiliary steam in the auxiliary steam hot standby subsystem enters the shaft seal supply main pipe through the shaft seal auxiliary steam pipe, so as to seal the steam turbine.

[0021] Preferably, the operation system further comprises a temperature measuring device located at the steam outlet of the auxiliary steam heating standby subsystem, the auxiliary steam heating standby subsystem comprising an auxiliary steam header, a heating device, a first auxiliary steam main pipe, an auxiliary steam supply pipe, a heating pipe and a second auxiliary steam main pipe, the heating device being located in the heating pipe, and the operation method further comprises:

[0022] Before the unit starts and the shaft seal system is self-sealed, when the temperature measured by the temperature measuring device is lower than the first temperature value, the heating device is started, the auxiliary steam in the auxiliary steam header flows through the first auxiliary steam main pipe, the heating device in the heating pipe and the second auxiliary steam main pipe in sequence to the pipe where the temperature measuring device is located, so that the temperature of the auxiliary steam is between the first temperature value and the second temperature value, and the system operates normally, when the temperature of the auxiliary steam is higher than the third temperature value, the heating device is turned off, the auxiliary steam in the auxiliary steam header flows through the first auxiliary steam main pipe, the auxiliary steam supply pipe and the second auxiliary steam main pipe in sequence to the pipe where the temperature measuring device is located, so that the temperature of the auxiliary steam is between the first temperature value and the second temperature value, and the system operates normally, until the temperature of the auxiliary steam is lower than the first temperature value, the heating device is started again, and the cycle is repeated; the third temperature value is greater than the second temperature value.

[0023] Compared with the prior art, the beneficial effects of the present application are that:

[0024] 1. The shaft seal system can effectively ensure the temperature of the shaft seal auxiliary steam in each stage of the unit, ensure the stable implementation of the shaft seal of the steam turbine, and improve the safety of the unit.

[0025] 2. By arranging the second drain pipe, the second drain pipe is communicated with the low-pressure heater, in the shaft seal self-sealing stage of the steam turbine, that is, in the auxiliary steam standby stage, the auxiliary steam and the drain formed by the auxiliary steam flow to the low-pressure heater, so that the auxiliary steam flows, the temperature of the shaft seal auxiliary steam is ensured, the use requirement can be met, and the heat of the shaft seal standby auxiliary steam and the drain is recovered to the low-pressure heater to heat the condensate water, which is more economical. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 The system overall schematic diagram of the embodiment in the present application.

[0028] Explanation of reference signs:

[0029] 1. auxiliary steam standby subsystem; 101. auxiliary steam header; 102. first auxiliary steam main; 103. auxiliary steam supply pipe; 104. second auxiliary steam main; 105. heating pipe; 106. heating device; 107. temperature measuring device; 108. auxiliary steam to shaft seal supply electric gate; 109. shaft seal supply electric gate; 2. steam turbine; 3. condenser; 4. low pressure heater; 5. shaft seal supply main pipe; 6. shaft seal auxiliary steam pipe; 7. first drain pipe; 8. second drain pipe; 9. shaft seal regulating valve; 10. first drain electric gate; 11. second drain electric gate; 12. check valve. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] The embodiment of the present application provides a shaft seal hot standby operation system, which comprises an auxiliary steam hot standby subsystem 1, a steam turbine 2, a condenser 3 and a low-pressure heater 4, wherein the auxiliary steam hot standby subsystem 1 is used for increasing auxiliary steam (hereinafter called auxiliary steam), in the embodiment, the steam outlet of the auxiliary steam hot standby subsystem is divided into three routes, wherein the first route is communicated with a shaft seal steam supply main pipe 5 through a shaft seal auxiliary steam pipe 6, the shaft seal auxiliary steam pipe 6 is provided with a shaft seal regulating valve 9, the shaft seal regulating valve 9 is used for controlling the opening and closing of the shaft seal auxiliary steam pipe 6, when the shaft seal system of the steam turbine 2 is not self-sealing, the auxiliary steam is supplied to the shaft seal steam supply main pipe 5 of the steam turbine 2 through the auxiliary steam hot standby subsystem 1, then the auxiliary steam enters the shaft end of the steam turbine 2 to realize steam sealing, thereby guaranteeing the normal operation of the steam turbine 2, the second route is communicated with the condenser 3 through a first drain pipe 7, the first drain pipe 7 is provided with a first drain valve electric door, which is used for controlling the opening and closing of the first drain pipe 7, before the auxiliary steam hot standby subsystem 1 supplies the auxiliary steam to the steam turbine 2, the first drain pipe 7 needs to be operated, the first drain electric door 10 is closed, so that the first drain pipe 7 is communicated, the auxiliary steam in the auxiliary steam hot standby subsystem 1 flows in the shaft seal auxiliary steam pipe, then enters the first drain pipe 7, and finally enters the condenser 3 to be converted into condensate water for reuse, the third route is communicated with the low-pressure heater 4 through a second drain pipe 8, the second drain pipe 8 is provided with a second drain electric door 11, which is used for controlling the opening and closing of the second drain pipe 8, when the steam turbine 2 is in the normal working condition, the shaft seal system of the steam turbine 2 is in the self-sealing stage, in order to guarantee that the temperature of the auxiliary steam in the auxiliary steam hot standby subsystem 1 does not decrease and the temperature difference between the auxiliary steam and the rotor metal temperature of the steam turbine 2 is within the range required by the manufacturer, the second drain electric door 11 is opened, so that the auxiliary steam in the auxiliary steam hot standby subsystem 1 and the drain water enter the low-pressure heater 4 through the second drain pipe 8, thereby the auxiliary steam can be kept in the flowing stage, once the steam flows, the temperature of the steam is not easy to decrease, the temperature can be kept, the temperature of the auxiliary steam is guaranteed when the steam turbine 2 uses the auxiliary steam for shaft sealing in the subsequent working condition of the unit, the stable shaft sealing of the steam turbine 2 in the unit is guaranteed, and the auxiliary steam and the drain water entering the low-pressure heater 4 can heat the condensate water passing through the low-pressure heater 4, the heat is recovered to increase the temperature of the condensate water, the steam extraction of the medium and low pressure cylinders of the steam turbine 2 is reduced to a certain extent, the power generation efficiency is increased, and compared with the prior art, the drain water and the auxiliary steam are periodically discharged into the condenser 3, so that the economy of the unit is greatly improved.

[0034] Specifically, the auxiliary steam heat standby subsystem 1 comprises an auxiliary steam header 101 and a heating device 106, wherein the steam outlet of the auxiliary steam header 101 is communicated with a shaft seal auxiliary steam main pipe, the steam of the auxiliary steam header 101 is supplied out through the shaft seal auxiliary steam main pipe, wherein the shaft seal auxiliary steam main pipe is connected with a heating pipe 105 in parallel, the heating device 106 is installed on the heating pipe 105, the heating device 106 can be an electric heater, which is used to increase the temperature of the auxiliary steam, so that the temperature difference between the auxiliary steam and the rotor metal of the steam turbine 2 is within the range required by the manufacturer, and the temperature value requirement of the auxiliary steam is met, when the temperature of the auxiliary steam is lower than the use requirement, the auxiliary steam enters the heating pipe 105, and then is heated by the heating device 106 and then enters the shaft seal auxiliary steam main pipe to be supplied out, and the like; wherein the conditions that the auxiliary steam needs to be heated generally include that the temperature of the steam source of the auxiliary steam header 101 is reduced, so that the temperature of the auxiliary steam discharged from the entire steam header is reduced, in addition, the outside temperature is low, so that the condensed drain water is increased, and the temperature difference causes the temperature of the auxiliary steam in the shaft seal auxiliary steam main pipe to be low, and the like; and the temperature of the auxiliary steam is increased by setting the electric heater relative to using another high-temperature steam to mix, without setting a redundant high-temperature steam supply channel, and the overall is more economical and practical. The above-mentioned temperature measuring device 107 can be a temperature sensor.

[0035] Specifically, the shaft seal auxiliary steam main pipe comprises a first auxiliary steam main pipe 102, an auxiliary steam supply pipe 103 and a second auxiliary steam main pipe 104, the second auxiliary steam main pipe 104 is communicated with the shaft seal auxiliary steam pipe 6, the first drain pipe 7 and the second drain pipe 8, the first auxiliary steam main pipe 102 is installed with an auxiliary steam to shaft seal supply electric door 108, the auxiliary steam supply pipe 103 is installed with a shaft seal supply electric door 109, the auxiliary steam supply pipe 103 is connected with the heating pipe 105 in parallel, and the heating device 106 is installed on the heating pipe 105; specifically, when the steam turbine 2 is not used, the auxiliary steam to shaft seal supply electric door 108 is closed, when the steam is supplied and the temperature of the auxiliary steam reaches the use requirement, the auxiliary steam to shaft seal supply electric door 108 and the shaft seal supply electric door 109 are opened, the auxiliary steam is supplied to the outside through the first auxiliary steam main pipe 102, the auxiliary steam supply pipe 103 and the second auxiliary steam main pipe 104, when the steam is supplied and the temperature of the auxiliary steam does not reach the use requirement, the auxiliary steam to shaft seal supply electric door 108 is opened and the shaft seal supply electric door 109 is closed, and the auxiliary steam is supplied to the outside through the first auxiliary steam main pipe 102, the heating pipe 105 and the second auxiliary steam main pipe 104.

[0036] Specifically, the second drain pipe 8 between the second drain electric door 11 and the low-pressure heater 4 is installed with a check valve 12, which avoids that the steam of the low-pressure heater 4 flows back into the shaft seal system to reduce the temperature of the shaft seal steam and endanger the safe operation of the entire unit.

[0037] The embodiment of the present application also provides a running method of the shaft seal heat standby running system, and specifically comprises the following steps.

[0038] Before the unit starts, that is, before the shaft seal system in the unit is put into operation, the first drain motor door 10 is opened, the first drain pipe 7 is connected, the shaft seal adjusting valve 9 and the second drain motor door 11 are closed, the auxiliary steam in the auxiliary steam standby subsystem enters the condenser 3 through the shaft seal auxiliary steam mother pipe and the first drain pipe 7 in turn, so as to heat the shaft seal auxiliary steam mother pipe, avoid the case that the temperature of the pipeline is too low to reduce the temperature of the auxiliary steam in the steam supply stage, and ensure that the pipeline does not affect the auxiliary steam in the subsequent steam supply initial stage; the above stage is until the unit starts, at this time, the first drain motor door 10 is closed, the shaft seal adjusting valve 9 is opened, and the shaft seal system auxiliary steam is put into operation.

[0039] When the unit is in the start-up and the shaft seal system in the unit is self-sealing or in the low load stage, the shaft seal adjusting valve 9 is opened, the shaft seal auxiliary steam pipe 6 is opened, and the first drain motor door 10 and the second drain motor door 11 are closed, the auxiliary steam in the auxiliary steam standby subsystem enters the shaft seal auxiliary steam pipe 6 through the shaft seal auxiliary steam mother pipe, and finally enters the shaft seal steam supply mother pipe 5, so as to seal the steam turbine 2 and assist the shaft seal of the steam turbine 2.

[0040] When the unit is in a certain load and the shaft seal system in the unit is self-sealing, specifically including the load rising stage and the high load stage, the second drain motor door 11 is opened, the second drain pipe 8 is opened, the shaft seal adjusting valve 9 and the first drain motor door 10 are closed, the auxiliary steam in the auxiliary steam standby subsystem and the drain enter the low-pressure heater 4 through the second drain pipe 8, which not only can keep the continuous flow of the auxiliary steam, keep the temperature of the auxiliary steam, avoid the case that too much drain causes the temperature of the auxiliary steam to drop, but also can heat the condensate water heated by the low-pressure heater 4, so as to reduce the steam extraction amount of the medium and low-pressure cylinder in the steam turbine 2, make more steam used for power supply or other purposes, compared with the existing shaft seal system, the auxiliary steam does not flow, a large amount of drain is generated, the temperature of the auxiliary steam is reduced, and the drain is regularly discharged into the condenser 3, which also increases the use burden of the condenser 3 and wastes the auxiliary steam, the system can not only ensure the temperature of the auxiliary steam, but also recycle the energy of the auxiliary steam, improve the economy of the unit as a whole. Moreover, the temperature of the auxiliary steam can be ensured in this stage, and when the unit is tripped or reduced to low load, the auxiliary steam can meet the steam use demand of the shaft seal of the steam turbine 2, ensure the stable shaft seal of the steam turbine 2, and ensure the safe operation of the unit.

[0041] Specifically, when the unit is in emergency shutdown, the shaft seal adjusting valve 9 is opened, the first drain motor door 10 and the second drain motor door 11 are closed, the auxiliary steam in the auxiliary steam standby subsystem enters the shaft seal steam supply mother pipe 5 through the shaft seal auxiliary steam pipe 6, and the steam turbine 2 is sealed.

[0042] Specifically, in order to make the temperature of the auxiliary steam meet the use requirements before the unit starts and the shaft seal system in the unit self-seals, that is, the temperature difference between the auxiliary steam and the rotor metal temperature of the steam turbine 2 is within the manufacturer's requirements, the operation method further includes:

[0043] Before the unit starts and the shaft seal system in the unit self-seals, the shaft seal system in the unit self-seals stage is the unit load increase and high load stage. When the temperature measured by the temperature measuring device 107 in the pipeline is lower than the first temperature value, the heating device 106 is started, so that the auxiliary steam in the auxiliary steam header 101 passes through the first auxiliary steam pipeline 102, the heating device 106 on the heating pipe 105 and the second auxiliary steam pipeline 104 to the temperature measuring device 107 in sequence, until the temperature of the auxiliary steam in the pipeline at the temperature measuring device 107 is between the first temperature value and the second temperature value, the temperature of the auxiliary steam is maintained, and then the operation is continued. At this time, the auxiliary steam can be supplied outward; when the temperature of the auxiliary steam is higher than the third temperature value, the heating device 106 is closed, and the operation is continued. At this time, the auxiliary steam can be supplied outward, until the temperature of the auxiliary steam is lower than the first temperature value, and the heating device 106 is started again, and the cycle is repeated. In the specific implementation process, the first temperature value, the second temperature value and the third temperature value and the power setting of the heating device 106 are set by the operator according to the actual operation of the shaft seal system, and the difference between the first temperature value, the second temperature value and the third temperature value and the rotor metal temperature of the steam turbine 2 is within the manufacturer's requirements, that is, when the temperature of the auxiliary steam is lower than the first temperature value, the heating device 106 is opened, so that the temperature value of the auxiliary steam rises to between the first temperature value and the second temperature value. Similarly, the third temperature value is also set in the same way. When the temperature of the auxiliary steam is higher than the third temperature value, the heating device 106 is closed, and the temperature value of the auxiliary steam will decrease to between the first temperature value and the second temperature value. Of course, the temperature of the auxiliary steam rises not only because of the heating of the heating device 106, but also because of the increase of the steam source temperature and the external large steam temperature, so that the temperature value of the auxiliary steam can always rise to the third temperature. At this time, the temperature of the auxiliary steam meets the use requirements. In order not to waste the electric energy of the heating device 106, the heating device 106 is closed to save electric energy, and the heating device 106 is an electric heater.

[0044] The temperature measuring device 107 is set to ensure that the temperature of the auxiliary steam always meets the use requirements when the steam turbine 2 needs to be sealed by the auxiliary steam (the steam turbine 2 starts the shaft seal operation stage, the unit load decreases to the low load stage, and the steam turbine 2 needs to be sealed by the auxiliary steam), ensures the stable operation of the shaft seal system of the steam turbine 2, and ensures the stable and safe operation of the unit.

[0045] The above embodiments are only the preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application, and any non-essential changes and replacements made by those skilled in the art on the basis of the present application shall fall within the protection scope of the present application.

Claims

1. A shaft seal thermal standby operation system, characterized in that, It includes an auxiliary steam heat standby subsystem, a steam turbine, a condenser, and a low-pressure heater, wherein the steam turbine is connected to a shaft seal steam supply header; The steam outlet of the auxiliary steam standby subsystem is connected to the shaft seal steam supply main pipe, the condenser and the low-pressure heater respectively via a shaft seal auxiliary steam pipe, a first drain pipe and a second drain pipe. The shaft seal auxiliary steam pipe, the first drain pipe, and the second drain pipe are respectively connected to the shaft seal regulating valve, the first drain electric valve, and the second drain electric valve.

2. The shaft seal hot standby operation system according to claim 1, characterized in that, The auxiliary steam backup subsystem includes an auxiliary steam header, a heating device, and a temperature measuring device. The steam outlet of the auxiliary steam header is connected to the shaft seal auxiliary steam header, and the shaft seal auxiliary steam header is connected in parallel to the heating pipe, and the heating device is installed on the heating pipe; The temperature measuring device is located at the connection between the shaft seal auxiliary steam header and the shaft seal auxiliary steam pipe, and is used to measure the temperature of the auxiliary steam, and is used in conjunction with the heating device.

3. The shaft seal hot standby operation system according to claim 2, characterized in that, The shaft seal auxiliary steam header includes a first auxiliary steam header, an auxiliary steam supply pipe, and a second auxiliary steam header. The auxiliary steam supply pipe is connected in parallel with the heating pipe, and the second auxiliary steam header is connected to the shaft seal auxiliary steam header, the first drain pipe, and the second drain pipe. The first auxiliary steam main is equipped with an electric valve for supplying auxiliary steam to the shaft seal, and the auxiliary steam supply pipe is equipped with an electric valve for supplying shaft seal.

4. The shaft seal hot standby operation system according to claim 1, characterized in that, A check valve is installed on the second drain pipe between the second drain electric valve and the low-pressure heater.

5. A method for operating the shaft seal hot standby system according to any one of claims 1-4, characterized in that, include: Before the unit starts up, the first drain electric valve is opened, the shaft seal regulating valve and the second drain electric valve are closed, and the auxiliary steam in the auxiliary steam hot standby subsystem enters the condenser through the first drain pipe, which ends when the unit starts up. When the unit is in the startup phase and before the shaft seal system self-seales or in the low load phase, the shaft seal regulating valve opens, and the first and second drain electric valves close. The auxiliary steam and drain in the auxiliary steam hot standby subsystem enter the shaft seal steam supply header through the shaft seal auxiliary steam pipe to seal the turbine. When the unit is under a certain load and the shaft seal system is self-sealing, the second drain electric valve opens, the shaft seal regulating valve and the first drain electric valve close, and the auxiliary steam in the auxiliary steam hot standby subsystem enters the low-pressure heater through the second drain pipe to maintain the continuous flow of auxiliary steam.

6. The operation method of the shaft seal hot standby operation system according to claim 5, characterized in that, In the event of an emergency shutdown of the unit, the shaft seal regulating valve opens, and the first and second drain electric valves close. Auxiliary steam from the auxiliary steam hot standby subsystem enters the shaft seal steam supply header through the shaft seal auxiliary steam pipe to seal the turbine shaft.

7. The operation method of the shaft seal hot standby operation system according to claim 6, characterized in that, The operating system also includes a temperature measuring device located at the steam outlet of the auxiliary steam hot standby subsystem. The auxiliary steam hot standby subsystem includes an auxiliary steam header, a heating device, a first auxiliary steam main, an auxiliary steam supply pipe, a heating pipe, and a second auxiliary steam main. The heating device is located inside the heating pipe. The operating method also includes: Before the unit starts up and during the self-sealing of its internal shaft seal system, when the auxiliary steam temperature in the pipeline measured by the temperature measuring device is lower than the first temperature value, the heating device is activated. The auxiliary steam in the auxiliary steam header passes sequentially through the first auxiliary steam main pipe, the heating device on the heating pipe, and the second auxiliary steam main pipe to the pipeline measured by the temperature measuring device, so that the auxiliary steam temperature is between the first and second temperature values, and the system operates normally. When the auxiliary steam temperature is higher than the third temperature value, the heating device is shut off. The auxiliary steam in the auxiliary steam header passes sequentially through the first auxiliary steam main pipe, the auxiliary steam supply pipe, and the second auxiliary steam main pipe to the pipeline measured by the temperature measuring device, so that the auxiliary steam temperature is between the first and second temperature values, and the system operates normally until the auxiliary steam temperature is lower than the first temperature value, at which point the heating device is activated again, and the cycle repeats; the third temperature value is higher than the second temperature value.

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