CN217712686U

CN217712686U - Impulse turbine

Info

Publication number: CN217712686U
Application number: CN202221875896.4U
Authority: CN
Inventors: 陶海亮; 王慧秀; 张陈慧; 李晓宇; 杨长生
Original assignee: Siemens Energy Inc
Current assignee: Siemens Energy Inc
Priority date: 2022-07-19
Filing date: 2022-07-19
Publication date: 2022-11-01
Anticipated expiration: 2032-07-19

Abstract

The utility model discloses an impulse steam turbine, this impulse steam turbine includes: the rotor is provided with a plurality of stage moving blades spaced along the axial direction; and an inner cylinder disposed inside the intake cylinder and outside the rotor, the inner cylinder being connected to the intake cylinder by a projection projecting radially outward at a front axial end of the inner cylinder, and a first chamber being formed between the intake cylinder and the inner cylinder, the first chamber communicating with the stage moving blades located midway downstream among the plurality of stage moving blades to allow steam from the stage moving blades located midway downstream to flow into the first chamber. The utility model discloses an impulse steam turbine can reduce the stress gradient of admission cylinder, reduce the thermal stress and improve the creep life-span, can also reduce the leakage of vapor seal simultaneously.

Description

Impulse steam turbine

Technical Field

The present invention relates generally to the field of steam turbines, and more particularly, to an impulse steam turbine.

Background

With increasing steam conditions, steam temperatures tend to reach even above 540 ℃ and pressures even above 13.0MPa, where higher design requirements are placed on the inlet cylinder. As the inlet steam temperature increases, it is desirable to select materials for the inlet cylinder that have higher strength and creep properties. Moreover, as the inlet steam pressure increases, higher design requirements are placed on the gland seal design of the front shaft of the steam turbine.

For higher temperature, higher pressure steam, increasing cylinder wall thickness or selecting higher performance materials is often used to meet strength design requirements. To reduce the greater leakage losses caused by high pressure steam, leakage is typically reduced by increasing the number of seal teeth. However, additional manufacturing and material costs are incurred with such a design.

SUMMERY OF THE UTILITY MODEL

In order to overcome the above-mentioned drawbacks of the prior art, the present invention provides an impulse turbine comprising an intake cylinder and a rotor provided in the intake cylinder, a plurality of stage moving blades spaced apart in an axial direction being provided on the rotor, wherein the impulse turbine further comprises an inner cylinder provided in the intake cylinder and outside the rotor, the inner cylinder being connected to the intake cylinder by a protrusion protruding radially outward at a front axial end of the inner cylinder, and a first chamber being formed between the intake cylinder and the inner cylinder, the first chamber being in communication with a stage moving blade located at a middle downstream among the plurality of stage moving blades to allow steam from the stage moving blade located at the middle downstream to flow into the first chamber.

With this arrangement, since the first chamber communicates with the stage moving blades located midway downstream to allow the steam of lower temperature from the stage moving blades located midway downstream to flow into the first chamber, it is possible to reduce the stress gradient of the intake cylinder of the steam turbine, reduce the thermal stress of the cylinder block, and improve the creep life.

Further, the impulse turbine further includes a nozzle provided in the cylinder and outside the rotor, the nozzle being provided on a front side of the inner casing in an axial direction and connected to the front axial end of the inner casing by a protrusion axially protruding from the nozzle, a second chamber being formed between the nozzle and the cylinder and the protrusion of the inner casing, wherein the protrusion of the inner casing is at least a part of a common chamber wall of the first chamber and the second chamber, and wherein at least one axial through hole for communicating the first chamber with the second chamber is provided in the protrusion of the inner casing so that steam from the stage moving blade located midway downstream flowing into the first chamber can flow into the second chamber.

By this arrangement, the first chamber is in communication with the second chamber by means of the axial through hole, the first and second chambers having the same steam temperature and pressure. Therefore, since low-temperature steam is also introduced into the second chamber, it is possible to reduce the temperature around the nozzle, thereby reducing thermal stress and preventing deformation, cracks, and the like of the nozzle chamber.

Further, the intake cylinder is provided with a radially inwardly projecting protrusion at a front axial end of the intake cylinder, wherein a gland seal is provided between the protrusion of the intake cylinder and the rotor in a radial direction.

Further, in an axial direction, the nozzle is disposed between the protruding portion of the intake cylinder and the protruding portion of the inner cylinder; a first labyrinth seal is provided between the nozzle and the rotor (2) in the radial direction, and is located on the front side of the plurality of stage moving blades in the axial direction.

Further, a third chamber is formed between a first stage moving blade located most upstream of the plurality of stage moving blades and the first labyrinth seal, wherein a pressure of the third chamber is an exhaust pressure of the first stage moving blade and is constant.

Further, one or more partitions respectively fitted with one or more stage moving blades of the plurality of stage moving blades located downstream of the first stage moving blade are installed on a radially inner side of the inner cylinder, wherein the second chamber communicates with the one or more stage moving blades so that a pressure of the second chamber can be adjusted by the one or more partitions.

With this arrangement, since the diaphragm fitted with any stage moving blade from the second stage moving blade to the downstream stage moving blade can be mounted on the inner cylinder, the pressure of the second chamber can be adjusted accordingly, thereby ensuring that the leakage amount of the gland seal is maintained at a low level.

Further, a nozzle chamber is formed in the nozzle, and a partition plate that fits the first-stage moving blade is provided at an outlet of the nozzle chamber.

Further, a plurality of second labyrinth seals are disposed between the gland seal and the rotor in a radial direction, and one or more gland seal chambers are formed within the gland seal and between the plurality of second labyrinth seals, the one or more gland seal chambers being connected to the field low pressure seal steam by extension pipes, respectively.

To sum up, with the aid of the utility model discloses an impulse steam turbine can reduce the stress gradient of admission cylinder, reduce thermal stress and improve creep life, can also reduce the leakage of vapor seal simultaneously.

Drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without undue limitation. In the drawings:

FIG. 1 is a schematic cross-sectional view illustrating a steam turbine according to an embodiment of the present invention; and

FIG. 2 is a schematic cross-sectional view illustrating a portion of the steam turbine of FIG. 1.

List of reference numerals

100. Steam turbine

1. Air inlet cylinder

11. Protrusion of air inlet cylinder

2. Rotor

21. First stage moving blade

22. Second stage moving blade

23. Third stage moving blade

24. Fourth stage moving blade

25. Moving blade of fifth stage

3. Inner cylinder

31. Protrusion of inner cylinder

4. Nozzle for spraying liquid

41. Projection of nozzle

5. Steam seal

61. First labyrinth seal

62. Second labyrinth seal

C1 The first chamber

C2 Second chamber

C3 Third chamber

C4 The fourth chamber

C5 The fifth chamber

H axial through hole

D baffle

Detailed Description

The technical solution in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings in the embodiments of the present invention. It should be noted that, in the case of no conflict, the embodiments and features of the embodiments of the present invention may be combined with each other.

As shown in fig. 1 and 2, the present invention provides an impulse steam turbine 100. The impulse turbine 100 includes a cylinder inlet 1 and a rotor 2 disposed in the cylinder inlet 1, and a plurality of stage moving blades spaced apart in an axial direction are provided on the rotor 2. The impulse turbine 100 may further include an inner casing 3, the inner casing 3 being disposed inside the intake cylinder 1 and outside the rotor 2. The inner cylinder 3 is connected to the intake cylinder 1 by a protrusion 31 that protrudes radially outward at a front axial end of the inner cylinder 3, and a first cavity C1 is formed between the intake cylinder 1 and the inner cylinder 3, the first cavity C1 communicating with the stage moving blades located midway downstream of the plurality of stage moving blades to allow steam from the stage moving blades located midway downstream to flow into the first cavity C1. Since the steam temperature in the vicinity of the stage moving blades located further downstream is lower, the stress gradient of the intake cylinder 1 of the steam turbine 100 can be reduced, the thermal stress of the cylinder block can be reduced, and the creep life can be improved by communicating the first chamber C1 with the stage moving blades located further downstream and allowing the steam having a lower temperature from the stage moving blades located further downstream to flow into the first chamber C1.

Here, as shown in fig. 1 and 2, the stage moving blades located at the middle and downstream may be third stage moving blades 23, but the present invention is not limited to this, and may be fourth stage moving blades 24, fifth stage moving blades 25, and the like, or may be second stage moving blades 22.

As shown in fig. 1 and 2, the impulse turbine 100 may further include a nozzle 4, and the nozzle 4 is disposed inside the intake cylinder 1 and outside the rotor 2. The nozzle 4 is disposed on the front side of the inner cylinder 1 in the axial direction and is connected to the front axial end of the inner cylinder by a projection 41 projecting axially from the nozzle 4. As shown in fig. 1 and 2, the left side in fig. 1 and 2 is the front side of the impulse turbine 100, that is, the upstream side with respect to the plurality of stage moving blades; the right side in fig. 1 and 2 is the rear side of the impulse turbine 100, that is, the downstream side with respect to the plurality of stage moving blades. A second chamber C2 may be formed between the nozzle 4 and the protrusion 31 of the intake cylinder 1 and the inner cylinder 3, wherein the protrusion 31 of the inner cylinder 3 is at least a part of a common cavity wall of the first chamber C1 and the second chamber C2, and wherein at least one axial through hole H for communicating the first chamber C1 with the second chamber C2 is provided in the protrusion 31 of the inner cylinder 3 so that steam from the stage moving blades located midway downstream, which flows into the first chamber C1, can flow into the second chamber C2. Thereby, the first chamber C1 is communicated with the second chamber C2 by means of the axial through hole H, and the first chamber C1 and the second chamber C2 have the same steam temperature and pressure. Therefore, since low-temperature steam is also introduced into the second chamber C2, the temperature around the nozzle 4 can be lowered, thereby reducing thermal stress and preventing deformation, cracks, and the like of the nozzle chamber C4.

As shown in fig. 1 and 2, the intake cylinder 1 can be provided at the front axial end of the intake cylinder 1 with a projection 11 projecting radially inwards, wherein in the radial direction a steam seal 5 is provided between the projection 11 of the intake cylinder 1 and the rotor 2.

In the axial direction, the nozzle 4 may be disposed between the protruding portion 11 of the intake cylinder 1 and the protruding portion 31 of the inner cylinder 3. A first labyrinth seal 61 may be provided between the nozzle 4 and the rotor 2 in the radial direction, and the first labyrinth seal 61 is located on the front side of the plurality of stage moving blades in the axial direction.

Specifically, a third chamber C3 may be formed between the first stage moving blades 21 located most upstream of the plurality of stage moving blades and the first labyrinth seal 61, wherein the pressure of the third chamber C3 is the intake pressure of the first stage moving blades 21 and is constant. On the radially inner side of the inner cylinder 3, one or more diaphragms D are mounted, which cooperate with one or more stage moving blades of the plurality of stage moving blades located downstream of the first stage moving blade 21, respectively, with which the second chamber C2 communicates, so that the pressure in the second chamber C2 can be regulated by the one or more diaphragms D. The leakage amount of the gland 5 (front gland) is related to the pressure difference between the second chamber C2 and the third chamber C3, the larger the pressure difference is, the larger the leakage amount is, and wherein the pressure of the third chamber C3 is the steam inlet pressure of the first stage moving blades 21 and is constant, so the leakage amount of the gland 5 is mainly determined by the pressure of the second chamber C2. Since the axial length of the inner casing 3 can be adjusted according to design requirements, i.e. the inner casing 3 can be provided with a partition D cooperating with any stage of moving blades from the second stage of moving blades 22 to the downstream, the pressure in the second chamber C2 can be adjusted accordingly, preferably the pressure in the second chamber C2 is adjusted to be as small as possible in relation to the pressure difference in the third chamber C3, thereby ensuring that the leakage of the gland seal 5 is maintained at a low level.

As shown in fig. 1 and 2, a nozzle chamber C4 may be formed in the nozzle 4, and a partition D that engages with the first-stage moving blades 21 may be provided at an outlet of the nozzle chamber C4. Further, a plurality of second labyrinth seals 62 may be provided between the gland seal 5 and the rotor 2 in the radial direction, and one or more gland chambers C5 may be formed within the gland seal 5 and between the plurality of second labyrinth seals 62, the one or more gland chambers C5 being connected to the on-site low-pressure seal steam through extension pipes, respectively. As shown in fig. 1 and 2, the gland 5 has two gland chambers C5, the two gland chambers C5 being connected by extension lines to on-site low pressure seal steam, typically 1.2Bara and 0.98Bara, respectively.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An impulse steam turbine, the impulse steam turbine (100) comprising an intake cylinder (1) and a rotor (2) provided in the intake cylinder (1), a plurality of stage moving blades being provided on the rotor (2) so as to be spaced apart in an axial direction, characterized in that the impulse steam turbine (100) further comprises:

an inner cylinder (3) disposed inside the intake cylinder (1) and outside the rotor (2), the inner cylinder (3) being connected to the intake cylinder (1) by a protrusion (31) protruding radially outward at a front axial end of the inner cylinder (3), and a first chamber (C1) being formed between the intake cylinder (1) and the inner cylinder (3), the first chamber (C1) communicating with a stage moving blade located midway downstream of the plurality of stage moving blades to allow steam from the stage moving blade located midway downstream to flow into the first chamber (C1).

2. The impulse turbine according to claim 1, characterized in that the impulse turbine (100) further comprises a nozzle (4) provided inside the intake cylinder (1) and outside the rotor (2), the nozzle (4) being provided at a front side of the inner cylinder (3) in the axial direction and connected to the front axial end of the inner cylinder by a protrusion (41) axially protruding from the nozzle (4), a second chamber (C2) being formed between the nozzle (4) and the protrusion (31) of the intake cylinder (1) and the inner cylinder (3),

wherein the protrusion (31) of the inner cylinder (3) is at least a part of a common cavity wall of the first and second chambers (C1, C2), and wherein at least one axial through hole (H) for communicating the first chamber (C1) with the second chamber (C2) is provided in the protrusion (31) of the inner cylinder (3) so that steam from the mid-downstream stage moving blades flowing into the first chamber (C1) can flow into the second chamber (C2).

3. Impulse turbine according to claim 2, characterized in, that the inlet cylinder (1) is provided with a radially inwardly protruding protrusion (11) at the front axial end of the inlet cylinder (1), wherein in radial direction a gland seal (5) is provided between the protrusion (11) of the inlet cylinder (1) and the rotor (2).

4. An impulse turbine according to claim 3, characterized in, that the nozzle (4) is arranged between the protrusion (11) of the inlet cylinder (1) and the protrusion (31) of the inner casing (3) in the axial direction; a first labyrinth seal (61) is provided between the nozzle (4) and the rotor (2) in the radial direction, and the first labyrinth seal (61) is located on the front side of the plurality of stage moving blades in the axial direction.

5. The impulse turbine according to claim 4, characterized in that a third chamber (C3) is formed between a first stage moving blade (21) located most upstream of the plurality of stage moving blades and the first labyrinth seal (61), wherein a pressure of the third chamber (C3) is a discharge pressure of the first stage moving blade (21) and is constant.

6. The impulse turbine according to claim 5, characterized in that one or more diaphragms (D) respectively cooperating with one or more stage moving blades of the plurality of stage moving blades located downstream of the first stage moving blade (21) are installed on a radially inner side of the inner casing (3), wherein the second chamber (C2) communicates with the one or more stage moving blades such that a pressure of the second chamber (C2) can be adjusted by the one or more diaphragms (D).

7. Impulse turbine according to claim 5, characterized in, that a nozzle chamber (C4) is formed in the nozzle (4), and that at the outlet of the nozzle chamber (C4) a diaphragm (D) is arranged cooperating with the first stage moving blades (21).

8. The impulse steam turbine according to claim 3, characterized in that a plurality of second labyrinth seals (62) are provided between the gland seal (5) and the rotor (2) in the radial direction, and that one or more gland chambers (C5) are formed in the gland seal (5) and between the plurality of second labyrinth seals (62), which one or more gland chambers (C5) are connected to the on-site low-pressure seal steam by an external connection pipe, respectively.