A split low-pressure shaft end self-sealing system

Abstract

The present invention relates to a split low-pressure shaft end self-sealing system, comprising a rotor; a plurality of steam seal structures, the plurality of steam seal structures are arranged along the axial direction of the rotor, and a gap is left between the inner wall of the steam seal structure and the outer wall of the rotor; a newly added steam inlet pipe, the newly added steam inlet pipe is used to connect the external steam source and the gap, so that the external steam enters the sealing teeth to form a steam seal curtain; each steam seal structure comprises a plurality of separate steam seal blocks, the plurality of separate steam seal blocks are arranged on the outer side of the rotor and form a complete ring shape, and a gap is left between the inner wall of the separate steam seal block and the outer wall of the rotor; a steam seal sleeve, the steam seal sleeve is arranged on the outer side of the separate steam seal block; the newly added steam inlet pipe is arranged on the separate steam seal block and the steam seal sleeve. The present invention achieves the suppression of steam leakage after the local gap is enlarged by splitting the circumferential separate steam seal block, and independently controlling it with a temperature sensor and an independent steam supply valve, so as to save the use of high-pressure steam while ensuring the working safety of the steam turbine.

Description

Technical Field

[0001] The invention belongs to the technical field of steam turbine sealing, and in particular relates to a split low-pressure shaft end self-sealing system. Background Art

[0002] With the advancement of green and low-carbon transformation, the proportion of non-fossil energy in power generation has also been steadily increasing. The increasing share of wind, nuclear and solar energy shows that positive progress has been made in adjusting and optimizing the energy structure. However, despite this, thermal energy still accounts for a large proportion of energy consumption and electricity production. Thermal power generation is one of the most traditional ways of power generation in the world. It uses fossil fuels (such as coal, oil or natural gas) as the main energy source, and uses the heat generated by combustion to heat water and generate steam, which in turn drives the steam turbine to generate electricity. With its mature technology, high equipment reliability, low unit power generation cost, strong peak-shaving capacity, and high energy density, it still plays an important role in power supply. However, with the increasingly severe environmental problems and climate change, it is necessary to continue to take measures to reduce its operating losses and further improve the performance of thermal power generation.

[0003] As one of the three main equipment in a thermal power plant, a steam turbine consists of a steam generator (boiler), a steam turbine, a rotor, a generator, a condenser, a feed pump, and a regulating system. The working principle of a steam turbine is based on a thermodynamic cycle, mainly the Rankine cycle. In this process, steam is heated to a high temperature and high pressure state in the boiler, and then accelerated and directed to the turbine blades through the nozzle to drive the turbine to rotate, thereby converting thermal energy into mechanical energy, thereby driving the generator to generate a steady stream of electricity. It can be said that the turbine rotation efficiency directly affects the operating efficiency and economic benefits of the entire unit.

[0004] However, when the steam turbine is running, the intermediate rotor rotates at high speed, while the cylinder, partition (or stationary blade ring) and other parts are stationary. Therefore, an appropriate gap must be left between the rotor and the stationary parts to prevent mutual friction. However, the existence of the gap will cause steam leakage, and the loss caused by it accounts for at least 40% of the total loss of the entire steam turbine, which will not only reduce the efficiency of the unit, but also seriously affect the safe operation of the unit. In addition, since the steam turbine rotor is a long-axis part with complex rotor dynamic characteristics, radial runout will occur during high-speed rotation and variable operating conditions. Over time, the circumferential sealing gap begins to become uneven, and leakage is serious in places where the sealing gap is large, especially causing the infiltration of non-condensable air, which seriously affects the efficiency of the unit. The traditional method is to ensure the sealing effect by increasing the steam seal pressure and increasing the air supply, but the high-pressure sealing steam loss is too much and the economy is poor.

[0005] Therefore, it is necessary to design a split low-pressure shaft end self-sealing system to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a split low-pressure shaft end self-sealing system to solve the above-mentioned problems, to suppress steam leakage after the local gap is enlarged, and to maintain the vacuum degree when the shaft sealing system fails, thereby ensuring the safety of the turbine operation.

[0007] To achieve the above object, the present invention provides the following solution: a split low-pressure shaft end self-sealing system, comprising

[0008] Rotor;

[0009] A plurality of steam seal structures, wherein the plurality of steam seal structures are arranged along the axial direction of the rotor, and a gap is left between the inner side wall of the steam seal structure and the outer side wall of the rotor;

[0010] A newly added steam inlet pipe is used to connect the external steam source and the gap, so that the external steam enters the inner sealing teeth to form a steam seal curtain;

[0011] Each of the steam seal structures comprises a plurality of separate steam seal blocks, which are sleeved on the outer side of the rotor to form a complete ring, and a gap is left between the inner side wall of the separate steam seal block and the outer side wall of the rotor;

[0012] A steam seal sleeve, the steam seal sleeve being arranged outside the separate steam seal block;

[0013] The newly added steam inlet pipeline is arranged on the separate steam seal block and the steam seal sleeve.

[0014] Preferably, the newly added steam inlet pipe includes a steam seal sleeve hole, a steam seal block hole, and a steam seal sleeve pipe. The steam seal sleeve hole and the steam seal sleeve pipe are opened on the steam seal sleeve. The steam seal block hole is opened on the separate steam seal block. The steam seal sleeve hole, the steam seal block hole, and the steam seal sleeve pipe allow external steam to enter the gap to form a steam seal curtain.

[0015] Preferably, the external steam includes steam leaked from the high-pressure cylinder and supplementary steam source.

[0016] Preferably, the separate steam seal block is formed by dividing a complete annular steam seal block, and the separate steam seal block is fan-shaped, with a dividing gap between two adjacent separate steam seal blocks.

[0017] Preferably, the steam seal sleeve pipeline is connected to a steam branch, a steam branch valve is provided on the steam branch, several of the steam branches are commonly connected to a steam branch pipe, a steam branch valve is provided on the steam branch pipe, several of the steam branch pipes are commonly connected to a steam pipeline, a steam main valve is provided on the steam pipeline, and the steam pipeline is connected to the leaked steam from the high-pressure cylinder and the supplementary steam source.

[0018] Preferably, the inner sealing teeth include a plurality of short tooth groups and a plurality of long teeth arranged at intervals, the short tooth group includes two short teeth arranged at intervals, the outer side wall of the rotor is provided with a plurality of outer convex surfaces and a plurality of inner concave surfaces, the outer convex surfaces are arranged at intervals from the inner concave surfaces, the two short teeth of the short tooth group correspond to the outer convex surfaces, and the long teeth correspond to the inner concave surfaces.

[0019] Preferably, the number of the steam seal structures is three, a steam supply chamber is arranged between the steam seal structure close to the inside of the low-pressure cylinder and the steam seal structure located in the middle, and a steam extraction chamber is arranged between the steam seal structure close to the external environment and the steam seal structure located in the middle.

[0020] Preferably, the steam between the steam supply chamber and the low-pressure cylinder flows from the steam supply chamber to the low-pressure cylinder, the steam between the steam supply chamber and the steam extraction chamber flows from the steam supply chamber to the steam extraction chamber, and the gas between the steam extraction chamber and the external environment flows from the external environment to the steam extraction chamber.

[0021] Preferably, the steam in the steam seal sleeve pipe between the steam supply chamber and the low-pressure cylinder flows from the steam supply chamber to the low-pressure cylinder through the inner sealing teeth, the steam in the steam seal sleeve pipe between the steam supply chamber and the steam extraction chamber flows from the steam supply chamber to the steam extraction chamber through the inner sealing teeth, and the gas between the steam extraction chamber and the external environment flows from the external environment to the steam extraction chamber through the inner sealing teeth.

[0022] Preferably, a temperature sensor is provided on a side of the separate steam seal block located between the steam supply chamber and the steam extraction chamber close to the steam extraction chamber.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects:

[0024] 1. The present invention mainly utilizes pipelines to transport external steam pressure to the inside of the shaft seal, and through holes or slits designed at the tooth ends, the steam flow forms a steam curtain in the middle cavity of the sealing teeth. The high-pressure steam curtain is used to prevent the diffusion of low-pressure steam, and a steam wall is formed on both sides of the steam supply of the shaft seal to prevent non-condensable steam from entering the low-pressure cylinder through the shaft seal. This makes it unnecessary to grind the deformed rotor at the low-pressure shaft end of the unit that has not been overhauled for a long time, thereby reducing air leakage caused by shaft seal wear and further affecting the vacuum of the unit.

[0025] 2. The complete steam seal block is designed in different areas. The complete steam seal body is divided into multiple symmetrical parts, and independent switches are set up to control the steam supply of each part of the steam seal body. A temperature sensor is set on the steam seal block to determine whether the steam leakage is aggravated according to the temperature changes in the steam seal block and the cavity.

[0026] 3. The present invention can adjust various external steam inputs through the control valve to realize the controllable steam curtain in the steam seal body. It can deal with the situation that the gap between the seal teeth and one side of the rotor increases when the rotor rotates eccentrically, resulting in increased local leakage, and focus on reinforcing the parts with serious steam leakage to ensure the system vacuum, greatly reduce the maintenance and maintenance costs of the low-pressure cylinder caused by shaft seal leakage in the power plant, and improve the economy of the unit.

[0027] 4. The newly added external steam of the present invention is independent of the original mother pipe steam supply. During normal operation, due to the steam replenishment of the newly added steam supply pipeline, a safer and more reliable self-sealing system of the low-pressure shaft end is established to ensure the efficient sealing performance of the low-pressure shaft seal of the steam turbine. When the original shaft seal steam supply suddenly fails, the steam supply of the present invention can serve as an emergency measure to increase the steam supply pressure, inhibit steam leakage and external non-condensable gas from entering the low-pressure cylinder, maintain the unit vacuum from decreasing, avoid the risk of sudden shutdown caused by this, and improve the stability of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0029] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 It is a schematic diagram of the steam seal structure of the present invention;

[0031] Figure 3 It is a front view of the steam seal structure of the present invention;

[0032] Figure 4 It is a cross-sectional view of the steam seal structure of the present invention;

[0033] Figure 5 It is a cross-sectional view of a separate steam seal block of the present invention;

[0034] Figure 6 It is the pipeline control diagram of the present invention;

[0035] Figure 7 This is an exploded view of the rotor and the separate steam seal block of the present invention.

[0036] Among them, 1. rotor; 2. separate steam seal block; 3. steam seal sleeve; 4. dividing gap; 5. steam seal sleeve hole; 6. steam seal block hole; 7. low-pressure cylinder wall; 8. steam supply chamber; 9. steam extraction chamber; 10. steam seal sleeve pipeline; 11. temperature sensor; 13. bolts; 14. internal sealing teeth; 15. steam pipeline; 16. steam main valve; 17. steam branch pipe; 18. steam sub-valve; 19. steam branch; 20. steam branch valve. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Reference Figures 1 to 7 As shown, the present invention provides a split low-pressure shaft end self-sealing system, comprising

[0040] Rotor 1;

[0041] A plurality of steam seal structures, wherein the plurality of steam seal structures are arranged along the axial direction of the rotor 1, and a gap is left between the inner side wall of the steam seal structure and the outer side wall of the rotor 1;

[0042] A new steam inlet pipe is added, and the new steam inlet pipe is used to connect the external steam source and the gap, so that the external steam enters the inner sealing teeth 14 to form a steam seal curtain;

[0043] Each steam seal structure includes a plurality of separate steam seal blocks 2, which are sleeved on the outside of the rotor 1 and form a complete ring, and a gap is left between the inner wall of the separate steam seal block 2 and the outer wall of the rotor 1;

[0044] A steam seal sleeve 3, which is arranged outside the separate steam seal block 2;

[0045] The newly added steam inlet pipeline is arranged on the separate steam seal block 2 and the steam seal sleeve 3.

[0046] To further optimize the plan, a new steam inlet pipe is added, including a steam seal sleeve hole 5, a steam seal block hole 6, and a steam seal sleeve pipe 10. The steam seal sleeve hole 5 and the steam seal sleeve pipe 10 are opened on the steam seal sleeve 3, and the steam seal block hole 6 is opened on the separate steam seal block 2. The steam seal sleeve hole 5, the steam seal block hole 6, and the steam seal sleeve pipe 10 allow external steam to enter the gap to form a steam seal curtain.

[0047] To further optimize the solution, the external steam includes the steam leaked from the high-pressure cylinder and the supplementary steam source.

[0048] According to a further optimized solution, the separate steam seal block 2 is divided from a complete annular steam seal block, the separate steam seal block 2 is fan-shaped, and a dividing gap 4 is left between two adjacent separate steam seal blocks 2 .

[0049] To further optimize the solution, the steam seal jacket pipeline 10 is connected to a steam branch 19, a steam branch valve 20 is provided on the steam branch 19, several steam branches 19 are commonly connected to a steam branch pipe 17, a steam branch valve 18 is provided on the steam branch pipe 17, several steam branch pipes 17 are commonly connected to a steam pipeline 15, a steam main valve 16 is provided on the steam pipeline 15, and the steam pipeline 15 is connected to the leaked steam from the high-pressure cylinder and the supplementary steam source.

[0050] The steam pipeline 15 and the steam branch pipe 17 can be connected by a T-type three-way interface to form a one-to-two pipeline. The steam branch pipe 17 and the steam branch 19 can be connected by a cross-type four-way interface and a T-type three-way interface to form a one-to-four pipeline. The specific connection method can be threaded connection; flange connection is used when the diameter is large.

[0051] A further optimized solution is that the inner sealing teeth 14 include a plurality of short tooth groups and a plurality of long teeth arranged at intervals, the short tooth group includes two short teeth arranged at intervals, the outer side wall of the rotor 1 is provided with a plurality of outer convex surfaces and a plurality of inner concave surfaces, the outer convex surfaces and the inner concave surfaces are arranged at intervals, the two short teeth of the short tooth group correspond to the outer convex surfaces, and the long teeth correspond to the inner concave surfaces.

[0052] According to a further optimization scheme, the number of steam seal structures is three, a steam supply chamber 8 is arranged between the steam seal structure close to the inside of the low-pressure cylinder and the steam seal structure located in the middle, and a steam extraction chamber 9 is arranged between the steam seal structure close to the external environment and the steam seal structure located in the middle.

[0053] In the present invention, only one steam seal structure is provided between the interior of the low-pressure cylinder and the steam supply chamber 8, between the steam supply chamber 8 and the steam extraction chamber 9, and between the steam extraction chamber 9 and the external environment. Two or more steam seal structures may be provided therebetween according to actual needs.

[0054] To further optimize the solution, the steam between the steam supply chamber 8 and the low-pressure cylinder flows from the steam supply chamber 8 to the low-pressure cylinder, the steam between the steam supply chamber 8 and the steam extraction chamber 9 flows from the steam supply chamber 8 to the steam extraction chamber 9, and the gas between the steam extraction chamber 9 and the external environment flows from the external environment to the steam extraction chamber 9.

[0055] A further optimized solution is that the steam in the steam seal sleeve pipe 10 between the steam supply chamber 8 and the low-pressure cylinder flows from the steam supply chamber 8 to the low-pressure cylinder through the internal sealing teeth 14, the steam in the steam seal sleeve pipe 10 between the steam supply chamber 8 and the steam extraction chamber 9 flows from the steam supply chamber 8 to the steam extraction chamber 9 through the internal sealing teeth 14, and the gas between the steam extraction chamber 9 and the external environment flows from the external environment to the steam extraction chamber 9 through the internal sealing teeth 14.

[0056] According to a further optimization scheme, a temperature sensor 11 is provided on a side of the separate steam seal block 2 between the steam supply chamber 8 and the steam extraction chamber 9 close to the steam extraction chamber 9 .

[0057] The present invention divides each level of the steam seal structure into four separate steam seal blocks 2. The separate steam seal blocks 2 are named as level 1 separate steam seal block 2, level 2 separate steam seal block 2 and level 3 separate steam seal block 2 in the order from the low-pressure cylinder to the outside of the rotor 1. Each level 2 separate steam seal block 2 is correspondingly provided with a temperature sensor 11. The temperature sensor 11 is located on the side of the separate steam seal block 2 close to the steam extraction chamber 9. The temperature sensor 11 is used to monitor the temperature of the flowing steam and the separate steam seal block 2 in real time.

[0058] The shaft seal air supply main pipe collects the steam leaked from the high-pressure end and transports it through a pipeline to the steam supply chamber 8 of the shaft seal system between the low-pressure cylinder and the external environment. The pressure in the steam supply chamber 8 is 0.03Mpa higher than the atmospheric pressure. The low-pressure cylinder is connected to the condenser of the steam turbine, and the interior is a vacuum environment; the steam extraction chamber 9 is connected to the shaft seal heater, which is used to absorb the steam in the shaft seal system and recover heat to improve the thermal efficiency of the system. At the same time, a micro-vacuum can be formed in the steam extraction chamber 9. Therefore, after the steam in the steam supply chamber 8 enters, on the one hand, it flows into the low-pressure cylinder, suppressing the steam leakage of the low-pressure cylinder; on the other hand, it flows into the steam extraction chamber 9, and the steam is recycled. Due to its micro-vacuum characteristics, the steam extraction chamber 9 absorbs gas from both sides, which can prevent the steam in the steam supply chamber 8 from leaking into the ambient air. The additional steam source comes from the leaked steam from the high-pressure cylinder or other supplementary steam sources, and enters the steam branch pipe 17 through the steam pipe 15, and then enters the steam branch 19 through the steam branch pipe 17. The steam seal sleeve 3 above the separated steam seal block 2 is opened through the steam seal sleeve pipe 10, and the steam branch 19 and the steam seal sleeve pipe 10 are connected by bolts, and then the additional steam enters the separated steam seal block 2 through the steam seal sleeve pipe 10. The separated steam seal block 2 is fixed to the steam seal sleeve 3 as a whole through the groove, and is fixed to the low-pressure cylinder wall 7 by bolts 13.

[0059] The annular separate steam seal block 2 is split into multiple parts. According to the divided separate steam seal block 2, the cavity between the separate steam seal block 2 and the rotor 1 can be divided into multiple parts. The steam seal sleeve 3 above each separate steam seal block 2 is penetrated by the steam seal sleeve pipe 10, and the external steam pressure is transmitted to the cavity between the inner sealing teeth 14 of the separate steam seal block 2 and the rotor 1 by using the steam seal sleeve pipe 10. By opening three steam seal block holes 6 in each separate steam seal block 2, the internal nozzle of the separate steam seal block 2 sends out a curtain-like steam flow with a certain speed and a certain thickness, so that the ejected steam flow forms a strong steam flow barrier, blocking the external non-condensable gas from entering the low-pressure cylinder.

[0060] The steam pipeline 15 is arranged in the space outside the low-pressure cylinder, and a steam main valve 16 is set on it. Due to the multi-stage setting of the separate steam seal block 2 in the shaft sealing system, a steam branch pipe 17 is set on the steam pipeline 15. The steam pipeline 15 adopts a steam main valve 16 to be responsible for the main gas path. It is divided into two from the rear end of the steam main valve 16, and is divided into two steam branch pipes 17 to control the 1st-level separate steam seal block 2 and the 2nd-level separate steam seal block 2. The steam branch valve 18 adopts a proportional electric control valve to ensure that the air intake of the steam branch pipe 17 can be adjusted in real time according to the working conditions. A plurality of steam branch valves 20 are respectively set for the separate steam seal block 2 at the rear section of each steam branch pipe 17, and the separate steam seal block 2 can be controlled separately.

[0061] At the same time, due to the eccentricity of the shaft system caused by years of operation of the unit, there is a serious leakage on one side. When leaking, low-temperature gas from the outside air often enters and cools the separate steam seal block 2. The temperature sensor 11 is inserted and fixed by punching holes at the edge of the two-stage separate steam seal block 2 to detect the temperature at the seal. When the temperature is abnormal, indicating a leak, the leak position and its adjacent split separate steam seal block 2 can be regulated, and the steam branch valve 20 connected thereto can be controlled to increase the steam flow and pressure to ensure the sealing effect. This design can accurately control the steam valve on the separate steam seal block 2 individually, so that it can not only detect the leak point but also accurately transport steam to block non-condensing steam.

[0062] The source and arrangement quantity of the new steam pipeline introduced from the outside world in the present invention are not fixed, and can be the same source as the original shaft seal air supply mother pipe, or can come from the high-pressure cylinder steam leakage or steam supplement from other positions; the position and number of the steam seal block holes 6 on the separate steam seal block 2 are not fixed. The steam seal block holes 6 on the separate steam seal block 2 are for providing an entry channel for additional steam, and their form and number are not fixed; the number of separate steam seal blocks 2 is not fixed, and the split design of the separate steam seal block 2 is for better suppressing the steam leakage caused by the increase of the circumferential gap to a certain local gap, and is not limited to the specific division of several separate steam seal blocks; the main application scenario mentioned in the present invention is the low-pressure shaft end sealing of the steam turbine, but it is also applicable to other situations requiring sealing between the rotor and the stator.

[0063] The present invention divides the whole circumferential separation steam seal block into multiple independently controlled separation steam seal blocks 2, and opens a steam seal block hole 6 on each separation steam seal block 2. By introducing external air supply, an annular steam curtain is realized in the cavity of the inner sealing tooth 14 in the separation steam seal block 2. The high-pressure steam curtain is used to prevent the diffusion of low-pressure steam, and steam walls are formed on both sides to prevent non-condensable steam from entering the low-pressure cylinder through the shaft seal. Due to the eccentric rotation of the rotor 1, the gap between the separation steam seal block 2 and the rotor 1 increases, which is easy to cause steam leakage. A temperature sensor 11 is set on the separation steam seal block 2 to monitor in real time to determine whether the steam leakage is aggravated, and the external air supply is adjusted by the steam valve on the pipeline to realize the separate control of the split separation steam seal block 2, so as to focus on the reinforcement of the serious steam leakage part and ensure the stability of the vacuum degree inside the low-pressure cylinder.

[0064] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0065] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the protection scope of the present invention.

Claims

1. A split low-pressure shaft end self-sealing system, characterized in that: include Rotor (1); A plurality of steam seal structures, wherein the plurality of steam seal structures are arranged along the axial direction of the rotor (1), and a gap is left between the inner side wall of the steam seal structure and the outer side wall of the rotor (1); A newly added steam inlet pipe is used to connect an external steam source and the gap, so that external steam enters the inner sealing teeth (14) to form a steam sealing curtain; Each of the steam seal structures comprises a plurality of separate steam seal blocks (2), wherein the plurality of separate steam seal blocks (2) are sleeved on the outside of the rotor (1) to form a complete ring, and the gap is left between the inner wall of the separate steam seal block (2) and the outer wall of the rotor (1); A steam seal sleeve (3), the steam seal sleeve (3) being arranged outside the separate steam seal block (2); The newly added steam inlet pipeline is arranged on the separate steam seal block (2) and the steam seal sleeve (3); The newly added steam inlet pipeline comprises a steam seal sleeve hole (5), a steam seal block hole (6), and a steam seal sleeve pipeline (10); the steam seal sleeve hole (5) and the steam seal sleeve pipeline (10) are arranged on the steam seal sleeve (3); the steam seal block hole (6) is arranged on the separate steam seal block (2); the steam seal sleeve hole (5), the steam seal block hole (6), and the steam seal sleeve pipeline (10) allow external steam to enter the gap to form a steam seal curtain; The split steam seal block (2) is formed by dividing a complete annular steam seal block. The split steam seal block (2) is fan-shaped, and a dividing gap (4) is left between two adjacent split steam seal blocks (2). There are three steam seal structures, a steam supply chamber (8) is provided between the steam seal structure close to the inside of the low-pressure cylinder and the steam seal structure located in the middle, and a steam extraction chamber (9) is provided between the steam seal structure close to the external environment and the steam seal structure located in the middle; A temperature sensor (11) is provided on a side of the separate steam seal block (2) located between the steam supply chamber (8) and the steam extraction chamber (9) close to the steam extraction chamber (9); Due to the eccentric rotation of the rotor (1), the gap between the separated steam seal block (2) and the rotor (1) increases, resulting in steam leakage. A temperature sensor (11) is provided on the separated steam seal block (2) to monitor in real time whether the steam leakage is aggravated, and the separated steam seal block (2) is independently controlled by adjusting the external air supply through the steam valve on the pipeline, so as to reinforce the part where the steam leakage is aggravated and ensure the stability of the vacuum degree inside the low-pressure cylinder.

2. A split low-pressure shaft end self-sealing system according to claim 1, characterized in that: The external steam includes the steam leaked from the high-pressure cylinder and the supplementary steam source.

3. A split low-pressure shaft end self-sealing system according to claim 2, characterized in that: The steam seal jacket pipe (10) is connected to a steam branch (19), a steam branch valve (20) is provided on the steam branch (19), a plurality of the steam branches (19) are commonly connected to a steam branch pipe (17), a steam branch valve (18) is provided on the steam branch pipe (17), a plurality of the steam branch pipes (17) are commonly connected to a steam pipeline (15), a steam main valve (16) is provided on the steam pipeline (15), and the steam pipeline (15) is connected to the leaked steam of the high-pressure cylinder and the supplementary steam source.

4. A split low-pressure shaft end self-sealing system according to claim 1, characterized in that: The inner sealing teeth (14) include a plurality of short tooth groups and a plurality of long teeth arranged at intervals, the short tooth group includes two short teeth arranged at intervals, the outer side wall of the rotor (1) is provided with a plurality of outer convex surfaces and a plurality of inner concave surfaces, the outer convex surfaces are arranged at intervals from the inner concave surfaces, the two short teeth of the short tooth group correspond to the outer convex surfaces, and the long teeth correspond to the inner concave surfaces.

5. A split low-pressure shaft end self-sealing system according to claim 1, characterized in that: The steam between the steam supply chamber (8) and the low-pressure cylinder flows from the steam supply chamber (8) to the low-pressure cylinder, the steam between the steam supply chamber (8) and the steam extraction chamber (9) flows from the steam supply chamber (8) to the steam extraction chamber (9), and the gas between the steam extraction chamber (9) and the external environment flows from the external environment to the steam extraction chamber (9).

6. A split low-pressure shaft end self-sealing system according to claim 1, characterized in that: The steam in the steam seal pipe (10) between the steam supply chamber (8) and the low-pressure cylinder flows from the steam supply chamber (8) through the inner sealing teeth (14) to the low-pressure cylinder, the steam in the steam seal pipe (10) between the steam supply chamber (8) and the steam extraction chamber (9) flows from the steam supply chamber (8) through the inner sealing teeth (14) to the steam extraction chamber (9), and the gas between the steam extraction chamber (9) and the external environment flows from the external environment through the inner sealing teeth (14) to the steam extraction chamber (9).

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