Steam turbine

Abstract

The steam turbine comprises a high-medium-pressure cylinder and a low-pressure cylinder, the high-medium-pressure cylinder comprises a high-medium-outer-pressure cylinder and a high-medium-inner-pressure cylinder, a high-medium-pressure steam sealing body is arranged in the high-medium-inner-pressure cylinder, and a C-shaped sealing ring is arranged at the joint of the high-medium-inner-pressure cylinder and the high-medium-pressure steam sealing body. The low-pressure cylinder comprises a low-external-pressure cylinder and a low-internal-pressure cylinder, and the low-internal-pressure cylinder comprises an upper half part low-pressure inner cylinder and a lower half part low-pressure inner cylinder which are connected with each other; a sealing groove is formed in the lower half low-pressure inner cylinder on the combination face of the upper half low-pressure inner cylinder and the lower half low-pressure inner cylinder, a sealing packing is installed in the sealing groove, and a sealing key is connected to the sealing packing. A low-pressure rotor shaft is arranged in the low-internal-pressure cylinder, the low-pressure rotor shaft is connected with a shaft end steam seal, the shaft end steam seal comprises a steam seal sleeve and a steam seal ring, the steam seal ring is connected with steam seal teeth, the steam seal teeth are clamped in a groove in the surface of the low-pressure rotor shaft, the steam seal ring is further connected with a contact type steam seal strip, and the contact type steam seal strip makes contact with the low-pressure rotor shaft in an abutting mode.

Description

Technical Field

[0001] The utility model belongs to the technical field of steam turbines, and in particular relates to a steam turbine. Background Art

[0002] A steam turbine is a rotating machine that uses superheated steam as its motive force and converts the thermal energy of steam into mechanical work. It is the most widely used prime mover in modern thermal power plants.

[0003] The steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder. The high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder are arranged and connected in sequence. A high-pressure rotor is arranged in the high-pressure cylinder, an intermediate-pressure rotor is arranged in the intermediate-pressure cylinder, and a low-pressure rotor is arranged in the low-pressure cylinder. The high-pressure rotor, the intermediate-pressure rotor and the low-pressure rotor are coaxially connected in sequence through a coupling. A shaft sealing system is arranged at the connection of each rotor to prevent steam leakage. A partition is arranged in the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder. The partition is usually arranged on the partition sleeve. The partition is used to fix the stationary blades of each stage of the steam turbine and prevent inter-stage steam leakage, and separate the flow part of the steam turbine into several stages.

[0004] In the existing steam turbines, the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are all inner and outer double-layer cylinder structures, which distributes the huge steam pressure borne by the original single-layer cylinder to the inner and outer cylinders, reducing the pressure difference and temperature difference of each layer of the cylinder. The cylinder wall and flange can be thinned accordingly. When the unit is started and stopped and the operating conditions are changed, the thermal stress is also reduced accordingly, which is conducive to shortening the start-up time and improving the load adaptability. The high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are all supported by bearings. Generally, the high-pressure cylinder and the medium-pressure cylinder are high-pressure and medium-pressure combined cylinder structures, and the low-pressure inner cylinder is generally a barrel-shaped structure, divided into two parts, the upper and lower halves, and the joint surface of the upper and lower halves is called the center dividing surface, that is, the joint surface between the inner cylinder and the outer cylinder of the low-pressure cylinder is the center dividing surface. When the steam turbine is running, the center dividing surface needs to be kept sealed to prevent leakage between the stages of the adjacent steam extraction chambers of the low-pressure cylinder.

[0005] A steam seal body is provided in the low-pressure cylinder. The small gap between the steam seal teeth of the steam seal body and the rotor shaft forms small steam chambers, so that the pressure of high-pressure steam in these steam chambers is gradually reduced, so as to achieve the purpose of reducing steam leakage.

[0006] The following problems often occur during the operation of the steam turbine:

[0007] (1) After long-term operation of the low-pressure inner cylinder, the gap between the center and the center surface may increase, causing steam leakage in this part.

[0008] (2) Steam leakage occurs at the low-pressure rotor shaft seal position in the low-pressure cylinder. Utility Model Content

[0009] In view of the deficiencies in the prior art, the utility model provides a steam turbine to solve the problem of steam leakage during operation of the existing steam turbine.

[0010] In order to solve the above problems, the utility model provides a steam turbine, which includes a high-pressure cylinder and a low-pressure cylinder. The high-pressure cylinder includes a high-pressure external pressure cylinder and a high-pressure internal pressure cylinder. The high-pressure internal pressure cylinder is arranged inside the high-pressure external pressure cylinder. A high-pressure steam seal body is arranged in the high-pressure internal pressure cylinder. The high-pressure steam seal body is located at the junction of the high-pressure side and the medium-pressure side of the high-pressure cylinder to separate the high-pressure part from the medium-pressure part. A C-type sealing ring is arranged at the connection between the high-pressure internal pressure cylinder and the high-pressure steam seal body.

[0011] The low-pressure cylinder includes a low-outer-pressure cylinder and a low-inner-pressure cylinder. The low-inner-pressure cylinder is arranged inside the low-outer-pressure cylinder. The low-outer-pressure cylinder includes an upper-half low-pressure outer cylinder and a lower-half low-pressure outer cylinder connected to each other. The low-inner-pressure cylinder includes an upper-half low-pressure inner cylinder and a lower-half low-pressure inner cylinder connected to each other. A sealing groove is provided on the joint surface of the upper-half low-pressure inner cylinder and the lower-half low-pressure inner cylinder. A sealing packing is installed in the sealing groove. A sealing key is connected to the sealing packing.

[0012] A low-pressure rotor shaft is arranged inside the low internal pressure cylinder, and a shaft end steam seal is connected to the low-pressure rotor shaft. The shaft end steam seal includes a steam seal sleeve and a steam seal ring. The steam seal ring is connected to steam seal teeth, and the steam seal teeth are clamped in the groove on the surface of the low-pressure rotor shaft. The steam seal ring is also connected to a contact steam seal strip, and the contact steam seal strip is in contact with the low-pressure rotor shaft. The steam seal sleeve is used for installing the steam seal ring.

[0013] Specifically, the contact type steam seal strip is a composite material steam seal strip.

[0014] Preferably, a medium-pressure partition sleeve is connected to the high- and medium-pressure external pressure cylinder, and a sealing ring is connected at the positioning shoulder of the high- and medium-pressure external cylinder and the medium-pressure partition sleeve.

[0015] A steam turbine provided by an embodiment of the utility model comprises a high- and medium-pressure cylinder and a low-pressure cylinder, a sealing groove is provided on the low-pressure inner cylinder located at the lower part on the center dividing surface of the low-pressure inner cylinder, a sealing packing is provided in the sealing groove, a sealing key is provided on the sealing packing, and the sealing key is squeezed by the low-pressure inner cylinder at the upper part to seal the center dividing surface of the low-pressure inner cylinder to prevent steam leakage from this part; a shaft end steam seal is provided on the low-pressure rotor of the low-pressure cylinder, the shaft end steam seal comprises a steam seal sleeve and a steam seal ring, a steam seal tooth is connected to the steam seal ring, the steam seal tooth is clamped in the groove on the surface of the low-pressure rotor shaft, the steam seal tooth is clamped in the groove on the surface of the low-pressure rotor shaft, and the corresponding steam seal teeth are designed according to the structure of the sealed part of the low-pressure rotor shaft, in addition, the contact steam seal strip on the steam seal body directly contacts with the low-pressure rotor shaft, even if the steam seal tooth is damaged, under the contact sealing of the contact steam seal strip, the steam in the low-pressure cylinder is difficult to leak from the low-pressure rotor shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a steam turbine provided by an embodiment of the utility model;

[0017] Figure 2 yes Figure 1 Schematic diagram of the connection structure of the middle and high pressure inner cylinder and the middle and high pressure steam seal body;

[0018] Figure 3 yes Figure 1 The structural diagram of the low internal pressure cylinder in the middle and lower part;

[0019] Figure 4 yes Figure 1 Schematic diagram of the sealing structure of the middle dividing surface of the medium and low internal pressure cylinder;

[0020] Figure 5 yes Figure 1 Schematic diagram of the structure of the shaft end steam seal of the medium and low pressure cylinders;

[0021] Figure 6 yes Figure 5 A magnified view of middle;

[0022] Figure 7 yes Figure 1 Schematic diagram of the connection structure between the medium and high pressure outer cylinders and the medium pressure partition sleeve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the utility model clearer, the specific embodiments of the utility model are described in detail below in conjunction with the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the utility model shown in the accompanying drawings and described according to the accompanying drawings are merely exemplary, and the utility model is not limited to these embodiments.

[0024] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0025] Figure 1 It is a structural schematic diagram of a steam turbine provided by an embodiment of the utility model. Figure 2 yes Figure 1 Schematic diagram of the connection structure between the medium and high pressure inner cylinder and the medium and high pressure steam seal body, see Figure 1 and Figure 2The steam turbine includes a high- and medium-pressure cylinder 1 and a low-pressure cylinder 2. The high- and medium-pressure cylinder 1 includes a high- and medium-pressure external pressure cylinder 11 and a high- and medium-pressure internal pressure cylinder 12. The high- and medium-pressure internal pressure cylinder 11 is arranged inside the high- and medium-pressure external pressure cylinder 12. A high- and medium-pressure steam seal body 120 is arranged in the high- and medium-pressure internal pressure cylinder 12. The high- and medium-pressure steam seal body 120 is located at the junction of the high-pressure side and the medium-pressure side of the high- and medium-pressure cylinder 1, separating the high-pressure part from the medium-pressure part. A C-type sealing ring 121 is arranged at the connection between the high- and medium-pressure internal pressure cylinder 11 and the high- and medium-pressure steam seal body 120.

[0026] Specifically, adding a C-type sealing ring between the high-pressure and medium-pressure steam seal bodies and the high-pressure and medium-pressure inner cylinders can reduce the leakage of high-pressure steam (after the regulating stage) to the medium-pressure steam inlet chamber.

[0027] Figure 3 yes Figure 1 The structural diagram of the low internal pressure cylinder in the middle and lower part. Figure 4 yes Figure 1 Schematic diagram of the sealing structure of the middle dividing surface of the medium and low internal pressure cylinder, see Figure 1 , Figure 2 and Figure 3 The low-pressure cylinder 2 includes a low-outer-pressure cylinder 21 and a low-inner-pressure cylinder 22. The low-inner-pressure cylinder 22 is arranged inside the low-outer-pressure cylinder 21. The low-outer-pressure cylinder 21 includes an upper low-pressure outer cylinder 211 and a lower low-pressure outer cylinder 212 that are connected to each other. The low-inner-pressure cylinder 22 includes an upper low-pressure inner cylinder 221 and a lower low-pressure inner cylinder 222 that are connected to each other. On the joint surface of the upper low-pressure inner cylinder 221 and the lower low-pressure inner cylinder 222, a sealing groove 223 is opened on the lower low-pressure inner cylinder 222, and a sealing packing 5 is installed in the sealing groove 223, and a sealing key 6 is connected to the sealing packing 5.

[0028] Specifically, when the clearance between the center planes of the low-pressure inner cylinder increases after long-term operation, adding sealing keys to the center planes of adjacent steam extraction chambers of the low-pressure inner cylinder can reduce steam leakage between stages.

[0029] Specifically, during installation, the sealing key is squeezed by the upper low-pressure inner cylinder to seal the center plane of the low-pressure inner cylinder and prevent steam leakage from adjacent steam extraction chambers of the inner cylinder.

[0030] Specifically, in this embodiment, a low-pressure partition is also provided in the low-pressure cylinder 2. In order to prevent steam leakage, the drainage on the low-pressure partition of the low-pressure cylinder can be optimized. For example, the drainage hole on the blade top of the low-pressure sub-final stage partition is partially blocked, and then a throttling orifice is added to the drainage pipe of the low-pressure sub-final stage to reduce steam leakage.

[0031] Specifically, in this embodiment, the low-pressure cylinder 2 is connected to the condenser, and a guide plate is arranged inside the throat of the condenser. By analyzing the throat flow field of the exhaust section of the low-pressure cylinder, a guide plate is arranged inside the throat to improve the flow field distribution of the tube bundle inlet, thereby improving the overall heat exchange capacity of the cooling tube bundle; at the same time, the vacuum tightness modification of the condenser is considered to further improve the heat exchange capacity of the condenser and improve the economic efficiency of the unit.

[0032] Figure 5 yes Figure 1 Schematic diagram of the structure of the shaft end steam seal of the medium and low pressure cylinders. Figure 6 yes Figure 5 For the enlarged view of A in the figure, see Figure 1 , Figure 5 and Figure 6 A low-pressure rotor shaft 23 is arranged inside the low-pressure internal pressure cylinder 22, and a shaft end steam seal 4 is connected to the low-pressure rotor shaft 23. The shaft end steam seal 4 includes a steam seal sleeve 41 and a steam seal ring 42. The steam seal ring 42 is connected with a steam seal tooth 43, and the steam seal tooth 43 is stuck in the groove on the surface of the low-pressure rotor shaft 23. The steam seal ring 42 is also connected with a contact steam seal strip 44, and the contact steam seal strip 44 is in contact with the low-pressure rotor shaft 23; the steam seal sleeve 41 is used to install the steam seal ring 42.

[0033] Specifically, when the contact steam seal strip 44 is used as a contact steam seal to seal the low-pressure rotor shaft 23, a T-shaped groove can be machined in the middle of the original steam seal ring at the actual production site, and the contact steam seal can be inserted into the groove. The spring on the back of the contact steam seal ring generates a pre-compression force, so that the contact steam seal strip is always in contact with the shaft. The steam seal strip of the contact steam seal is a composite material with good wear resistance and self-lubricating properties. Adding a circle of contact steam seal to the low-pressure end steam seal can reduce the leakage of the low-pressure shaft seal and ensure the vacuum degree of the low-pressure cylinder.

[0034] Figure 7 yes Figure 1 For the schematic diagram of the connection structure between the medium and high pressure outer cylinder and the medium pressure partition sleeve, refer to Figure 1 and Figure 2 The high and medium pressure external pressure cylinder 11 is connected to a medium pressure partition sleeve 7, and a sealing ring 8 is connected to the positioning shoulder of the high and medium pressure external cylinder 11 and the medium pressure partition sleeve 7.

[0035] Specifically, adding a sealing ring 8 between the positioning shoulder of the medium-pressure diaphragm sleeve 7 and the high- and medium-pressure outer cylinders 11 can reduce the leakage of steam from the steam turbine 3 to the medium-pressure exhaust. In addition, adding a sealing key to the middle dividing surface of the medium-pressure diaphragm sleeve 7 can also reduce the leakage of steam from the steam turbine 3 to the medium-pressure exhaust.

[0036] In this example, the steam turbine described above mainly seals the steam seal body between high and medium pressure; adds sealing keys and packings to the low-pressure inner cylinder and low-pressure steam inlet chamber; adds a circle of contact steam seal to the low-pressure end steam seal; and adds a sealing device to the medium-pressure partition sleeve. Compared with the low flow modification of the entire machine, the sealing in this example has a higher cost-effectiveness, and the steam turbine can reduce the heat consumption by no less than 50kJ / kW.h.

[0037] In summary, the steam turbine provided by the embodiment of the utility model can solve the problem of steam leakage during operation of the existing steam turbine.

[0038] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A steam turbine, characterized in that: The steam turbine comprises a high-pressure cylinder (1) and a low-pressure cylinder (2), wherein the high-pressure cylinder (1) comprises a high-pressure external pressure cylinder (11) and a high-pressure internal pressure cylinder (12), wherein the high-pressure internal pressure cylinder (12) is arranged inside the high-pressure external pressure cylinder (11), wherein a high-pressure intermediate steam seal body (120) is arranged in the high-pressure intermediate steam seal body (120), wherein the high-pressure intermediate steam seal body (120) is located at the junction of the high-pressure side and the medium-pressure side of the high-pressure cylinder (1), and separates the high-pressure part from the medium-pressure part, and a C-shaped sealing ring (121) is arranged at the connection between the high-pressure internal pressure cylinder (12) and the high-pressure intermediate steam seal body (120); The low-pressure cylinder (2) comprises a low-pressure outer cylinder (21) and a low-pressure inner cylinder (22), wherein the low-pressure inner cylinder (22) is arranged inside the low-pressure outer cylinder (21), and the low-pressure outer cylinder (21) comprises an upper low-pressure outer cylinder (211) and a lower low-pressure outer cylinder (212) which are connected to each other; the low-pressure inner cylinder (22) comprises an upper low-pressure inner cylinder (221) and a lower low-pressure inner cylinder (222) which are connected to each other; a sealing groove (223) is provided on the lower low-pressure inner cylinder (222) on the joint surface of the upper low-pressure inner cylinder (221) and the lower low-pressure inner cylinder (222), a sealing packing (5) is installed in the sealing groove (223), and a sealing key (6) is connected to the sealing packing (5); A low-pressure rotor shaft (23) is arranged inside the low-pressure internal pressure cylinder (22), and a shaft end steam seal (4) is connected to the low-pressure rotor shaft (23). The shaft end steam seal (4) includes a steam seal sleeve (41) and a steam seal ring (42). The steam seal ring (42) is connected to a steam seal tooth (43), and the steam seal tooth (43) is stuck in a groove on the surface of the low-pressure rotor shaft (23). The steam seal ring (42) is also connected to a contact steam seal strip (44), and the contact steam seal strip (44) is in abutment with the low-pressure rotor shaft (23); the steam seal sleeve (41) is used to install the steam seal ring (42).

2. The steam turbine according to claim 1, characterized in that The contact type steam seal strip (44) is a composite material steam seal strip.

3. The steam turbine according to claim 1, characterized in that: The high and medium external pressure cylinder (11) is connected to a medium pressure partition sleeve (7), and a sealing ring (8) is connected to the positioning shoulder of the high and medium external pressure cylinder (11) and the medium pressure partition sleeve (7).

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