阅读说明：本技术 一种高压汽轮机叶顶汽封结构 (High pressure steam turbine blade top gland structure ) 是由 崔亚辉 张俊杰 李雪松 张晓旭 刘红 钟明磊 王路遥 渠福来 孙鹏 徐亚涛 赵宗 于 2020-12-29 设计创作，主要内容包括：本发明公开一种高压汽轮机叶顶汽封结构,包括多个高压缸,每个所述高压缸包括：转子,周向设置在所述转子上的叶片,设置在叶片顶部上的凸台,以及汽封块；其中,所述汽封块包括多个密封齿,所述汽封块通过所述密封齿与所述叶片顶部上的凸台形成密封腔；所述凸台的数量为一个。本发明提供的高压汽轮机叶顶汽封结构,可以提高密封转子的稳定性。(The invention discloses a high-pressure turbine blade top steam seal structure, which comprises a plurality of high-pressure cylinders, wherein each high-pressure cylinder comprises: the steam turbine comprises a rotor, blades circumferentially arranged on the rotor, a boss arranged on the top of each blade, and a steam seal block; the steam seal block comprises a plurality of seal teeth, and a seal cavity is formed by the steam seal block and a boss on the top of the blade through the seal teeth; the number of the bosses is one. The high-pressure turbine blade top steam seal structure provided by the invention can improve the stability of the seal rotor.)

1. A high pressure turbine tip gland seal structure comprising a plurality of high pressure cylinders, each high pressure cylinder comprising:

the steam turbine comprises a rotor, blades circumferentially arranged on the rotor, a boss (61) arranged on the top (50) of each blade, and a steam seal block;

wherein the steam seal block comprises a plurality of seal teeth, and a seal cavity is formed by the steam seal block and a boss (61) on the blade top (50) through the seal teeth;

the number of the bosses (61) is one.

2. The high pressure turbine blade tip gland seal structure of claim 1, wherein the high pressure cylinder is a regulation stage high pressure cylinder, a 1 stage high pressure cylinder, a 2 stage high pressure cylinder, a 3 stage high pressure cylinder, a 4 stage high pressure cylinder, a 5 stage high pressure cylinder, a 6 stage high pressure cylinder, a 7 stage high pressure cylinder or an 8 stage high pressure cylinder in the high pressure turbine.

3. The high pressure turbine bucket tip gland seal configuration according to claim 1, wherein said plurality of seal teeth includes long seal teeth, short seal teeth, and flat seal teeth.

4. The high pressure turbine bucket tip gland seal configuration according to claim 1 wherein said gland seal block includes 8 seal teeth.

5. The high pressure turbine blade tip gland seal structure according to claim 4, wherein the gland seal block comprises a first long seal tooth (41), a second flat seal tooth (42), a third short seal tooth (43), a fourth short seal tooth (44), a fifth flat seal tooth (45), a sixth long seal tooth (46), a seventh long seal tooth (47) and an eighth long seal tooth (48) in sequence along the incoming flow direction of the air flow.

6. The high pressure turbine tip gland seal configuration according to claim 5, wherein said boss (61) is opposite said third short seal tooth (43), said fourth short seal tooth (44).

7. The high pressure turbine blade tip gland seal configuration according to claim 1, wherein said blade is divided into a first portion and a second portion along a line perpendicular to the incoming flow direction of the gas stream, said boss (61) being provided on the top of the first portion of the blade.

8. The high pressure turbine blade tip gland seal according to claim 1 wherein said seal teeth and said lands (61) have a gap therebetween, said gap having an axial height of 0.5-1.5 mm.

9. The high pressure turbine blade tip gland seal according to claim 8 wherein said seal teeth and said lands (61) have a gap therebetween, said gap having an axial height of 0.8 mm.

10. The high pressure turbine blade tip gland seal structure according to claim 9, wherein the rotor is further provided with a prerotation piece, the prerotation piece is arranged in front of an airflow inlet, and the airflow inlet is a gap between a first seal tooth and the boss along an airflow incoming flow direction;

based on the angle of the incoming flow of the inlet, the angle of the prewhirl plate is as follows:

the inlet angle of the prewhirl plate is as follows: the inlet inflow angle is typically plus 60 degrees;

the exit angle of the prewhirl plate is as follows: 0 degree.

Technical Field

The invention relates to the technical field of rotary mechanical seal, in particular to a blade top steam seal structure of a high-pressure steam turbine.

Background

With the development of the power generation industry in China, the capacity of the unit is increased from 600MW grade to 1000MW grade, but because of the insufficient technical capability, the 1000MW grade unit in China is introduced first. The introduced Hitachi 1000MW high-pressure turbine has low efficiency and needs to be improved, and the improvement and optimization of the high-pressure turbine blade top steam seal structure is one of the methods.

Disclosure of Invention

The invention discloses a blade top steam seal structure of a high-pressure steam turbine, which aims to solve the technical problem that the efficiency of the high-pressure steam turbine is low due to the fact that the stability of a seal rotor is low in the prior art.

In order to solve the problems, the invention adopts the following technical scheme:

according to a first aspect of the present invention, there is provided a high pressure turbine blade tip gland seal structure comprising a plurality of high pressure cylinders, each of said high pressure cylinders comprising: the steam turbine comprises a rotor, blades circumferentially arranged on the rotor, a boss arranged on the top of each blade, and a steam seal block; the steam seal block comprises a plurality of seal teeth, and seal cavities are formed by the steam seal block, the blades and bosses on the tops of the blades through the seal teeth; the number of the bosses is one.

Optionally, the high-pressure cylinder is a regulating step high-pressure cylinder, a 1 step high-pressure cylinder, a 2 step high-pressure cylinder, a 3 step high-pressure cylinder, a 4 step high-pressure cylinder, a 5 step high-pressure cylinder, a 6 step high-pressure cylinder, a 7 step high-pressure cylinder or an 8 step high-pressure cylinder in the high-pressure turbine.

Optionally, the plurality of seal teeth includes long seal teeth, short seal teeth, and flat seal teeth.

Optionally, the gland block comprises 8 sealing teeth.

Optionally, along the airflow incoming flow direction, the steam seal block sequentially comprises 1 long seal tooth, 1 flat seal tooth, 2 short seal teeth, 1 flat seal tooth and 3 long seal teeth.

Optionally, the boss is opposite the 2 short seal teeth.

Optionally, the vane is divided into a first portion and a second portion along a line perpendicular to the incoming flow direction of the airflow, and the boss is disposed on top of the first portion of the vane.

Optionally, a gap is formed between the seal tooth and the boss, and the axial height of the gap is 0.5-1.5 mm.

Optionally, a gap is formed between the seal tooth and the boss, and the axial height of the gap is 0.8 mm.

Optionally, the rotor is further provided with a prewhirl plate, the prewhirl plate is arranged in front of an airflow inlet, and the airflow inlet is a gap between a first sealing tooth and the boss along an airflow incoming flow direction;

the pre-swirl plate typically has an inlet angle of 60 degrees and an outlet angle of zero degrees, based on the inlet incoming flow angle.

In this application, "prewhirl" refers to the inlet circumferential velocity of the seal;

the inlet angle of the prerotation vane is the inlet inflow angle, typically 60 degrees positive.

The outlet angle of the prerotation piece is 0 degree, for example, the angle of the prerotation piece relative to the axial direction, 0 degree represents parallel to the axial direction, and a positive value represents that the circumferential speed is the same as the rotation direction of the rotor.

The technical scheme adopted by the invention can achieve the following beneficial effects:

the high-pressure turbine blade top steam seal structure provided by the invention can improve the stability of the seal rotor.

Drawings

The accompanying drawings, which 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 and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural diagram of a conventional high-pressure tip gland seal structure of a steam turbine;

FIG. 2a is a model diagram of an original tip gland seal structure with two boss structures modeled;

FIG. 2b is a model diagram of an original blade tip seal structure after modeling the blade tip seal structure formed by removing the rear boss structure;

FIG. 3a is a high pressure stage seal grid distribution axial plan sectional view of a raw tip gland seal configuration with two boss configurations;

FIG. 3b is an axial cross-sectional view of a high pressure stage seal grid distribution of the original tip gland structure formed after removal of the rear boss structure;

FIG. 4a is a streamline distribution diagram of an original tip gland seal configuration with two boss configurations;

FIG. 4b is a flow line distribution diagram of a blade tip gland seal structure formed after the original blade tip gland seal structure is removed of the rear boss structure;

FIG. 5 is a schematic structural view of a tip gland seal according to the present invention.

Description of reference numerals:

1 first stage stress surface

2 second section of bearing surface

3 third stage stress surface

4 fourth section stress surface

5 fifth section of stress surface

6 sixth section stress surface

7 seventh segment stress surface

8 eighth stress surface

9 ninth section stress surface

11, 18 long seal teeth

13, 14, 16, 17 short seal teeth

12, 15 flat seal teeth

31 front boss

30 rear boss

41 first long seal tooth

42 second flat seal tooth

43 third short seal tooth

44 fourth short seal tooth

45 fifth flat seal tooth

46 sixth long seal tooth

47 seventh long seal tooth

48 eighth long seal tooth

50 blade tip

61 boss

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The technical scheme disclosed by each embodiment of the invention is explained in detail below with reference to the accompanying drawings;

in the present application, the same reference numerals are used to denote the same components.

Analyzing the influence of the rear lug boss on the performance of the high-pressure turbine:

the high-pressure cylinder of the introduced 1000MW unit comprises 9 levels in total, and is sequentially of an adjusting level and a high pressure level of 1-8.

Fig. 1 is a geometric structure diagram of a high-pressure first stage of a turbine of a conventional 1000MW unit. The labyrinth seal structure is a labyrinth seal structure with a front boss 31 and a rear boss 30, wherein the front boss 31 and the rear boss 30 are arranged on the blade top 50, and two short seal teeth are distributed on each boss, for example, two short seal teeth 13 and 14 are distributed on the front boss 31; two short sealing teeth 16, 17 are distributed on the rear boss 30. In addition to the boss, 2 long seal teeth 11, 18 and 2 flat seal teeth 12, 15 are arranged.

For the other stages of the high pressure stage of the turbine, the sealing pattern of the other stages is substantially the same as that of the first stage except for the difference in geometry.

Since the seal structure of each stage of the high pressure stage of the steam turbine is the same as that of the first stage, only the first stage will be analyzed in detail in the following of the present invention. The resulting sealing structure is also suitable for use at other stages in terms of leakage characteristics, rotor dynamics influencing factors and improvement methods.

In order to obtain detailed leakage characteristics and rotor dynamic characteristics of such a seal structure, it is necessary to perform modeling analysis. The first sealing tooth and the last sealing tooth are used as an inlet and an outlet. Considering the axial displacement of the actual turbine during operation, the axial distance between the boss teeth and the boss is removed during modeling, so that the boss is aligned with the boss teeth, as shown in fig. 2 a. Meanwhile, the latter boss of the high-pressure first-stage shroud ring sealing material object is removed. For comparison, the analysis is modeled here together with the original structure, as shown in fig. 2 b. In fig. 2a and 2b, the force-bearing surface of the radial force of the rotor is subdivided into a first force-bearing surface section 1, a second force-bearing surface section 2, a third force-bearing surface section 3, a fourth force-bearing surface section 4, a fifth force-bearing surface section 5, a sixth force-bearing surface section 6, a seventh force-bearing surface section 7, an eighth force-bearing surface section 8 and a ninth force-bearing surface section 9, that is, the force-bearing surface of the radial force of the rotor is subdivided into 9 force-bearing surface sections, specifically, as shown by numerals in fig. 2a and 2b, so as to study the acting ratio of each force-bearing surface section to the force-bearing surface and the stability of the rotor in detail. In fig. 2a and 2b, the inlet is a gap inlet of the 1 st tooth, the outlet is a gap outlet of the 8 th tooth, and two sides of the left and right boundaries respectively refer to the 1 st tooth and the 8 th tooth.

The computational mesh is generated using ICEM, and the axial plan cross-sectional view of the mesh distribution is shown in FIGS. 3a and 3 b. The three-dimensional mesh generated by rotating the planar mesh in the circumferential direction, the final mesh count is about 245 ten thousand mesh points.

Performing numerical simulation by adopting ANSYS CFX, setting pressure at an inlet and an outlet, and setting the pressure value according to actual operation parameters of the steam turbine; the inlet velocity direction is perpendicular to the inlet face, i.e. a zero pre-swirl condition. And calculating the dynamic characteristic coefficient of the rotor by adopting a whirling rotor method. The swirl frequency is set with reference to the half-frequency swirl state of the turbine operation.

Fig. 4a and 4b show the seal flow line profiles for two different configurations, respectively. Thus in the high pressure stage flow diagram of figure 4a there is only one large vortex in the chamber before the boss and two opposite directed vortices are present in the chamber after the boss. The boss is limited by 2 short seal teeth, so the vortex system is simpler than 1 short seal tooth. Comparing fig. 4a and 4b, the upstream flow conditions are substantially unchanged and the downstream variations are greater after removal of the rear boss. And, after the rear boss is removed, the pressure level on the front boss is reduced and the overall pressure of the seal at the rear section is reduced.

Table 1 shows a comparison of the coefficients of rotor dynamics for two different seal configurations. The result shows that after the rear boss is removed, although the leakage amount is slightly increased, the main damping is increased, the cross rigidity is reduced, the stability criterion is reduced, and the improvement of the stability of the sealed rotor is facilitated.

TABLE 1 comparison of rotor dynamic coefficient of original and after removal of rear boss

And carrying out detailed segmental analysis on the dynamic characteristic coefficient of the rotor of the high-pressure stage labyrinth seal. The segmentation is already given in fig. 2a and 2 b. Table 2 lists the rotor dynamics parameters for each section. It can be seen from the table that the contribution of the seal at the position of the boss at the previous section to the main damping coefficient is increased after the rear boss is removed; the seal at the rear boss position itself contributes less to the primary damping; the overall primary damping coefficient increases. For the cross stiffness coefficient, after the rear boss is removed, positive cross stiffness appears at the front section of the seal, so that the negative cross stiffness of the rear section is neutralized, and the total cross stiffness value is reduced. As can be seen from Table 1, the vortex frequency ratio is small after the boss structure is removed, which indicates that the stability of the rotor is good.

TABLE 2 detailed segmental analysis of rotor dynamic coefficient for original and after removal of the rear boss

Analyzing the influence of the prerotation piece on the performance of the high-pressure turbine:

in an actual steam turbine, under the condition of not adding a prerotation sheet, airflow enters a high-pressure steam turbine blade top steam seal structure at a certain incident angle. The inventor finds that the dynamic characteristics of the rotor have influence in different prerotations, and researches the cross rigidity, the main damping and the vortex frequency ratio of the original structure and the two structures without the rear lug bosses under different prerotations (the inlet circumferential speeds are respectively 0m/s, +120m/s and-120 m/s), and the results are shown in table 3:

TABLE 3 Effect of prerotation on the dynamic behavior of high-pressure stage sealed rotors

The calculation of different prerotations shows that when the prerotation is zero, the absolute value of the cross rigidity is minimum, the stability criterion is minimum and the rotor stability is best no matter the original two boss structures or the blade top steam seal structure with the boss removed. In the case of pre-rotation (+120m/s or-120 m/s), the damping value is compared between the original structure and the structure with the rear step removed, and it can also be seen that the damping is increased after the rear step is removed.

The following is a specific embodiment of the high pressure turbine blade tip gland seal structure of the present invention:

as shown in fig. 5, according to an embodiment of the present invention, there is provided a high pressure turbine blade tip gland seal structure including a plurality of high pressure cylinders, each high pressure cylinder including: a rotor, blades circumferentially arranged on the rotor, bosses 61 arranged on the blade tips 50, and a steam seal block; the steam seal block comprises a plurality of seal teeth, and a seal cavity is formed by the steam seal block and the boss 61 of the blade top part 50 through the seal teeth; the number of the bosses 61 is one. Wherein the boss 61 and the blade may be integrally formed.

Specifically, the high-pressure cylinder may be a regulation stage high-pressure cylinder, a 1 stage high-pressure cylinder, a 2 stage high-pressure cylinder, a 3 stage high-pressure cylinder, a 4 stage high-pressure cylinder, a 5 stage high-pressure cylinder, a 6 stage high-pressure cylinder, a 7 stage high-pressure cylinder, or an 8 stage high-pressure cylinder in the high-pressure turbine.

Specifically, the plurality of seal teeth includes long seal teeth, short seal teeth, and flat seal teeth. The long seal teeth, the short seal teeth and the flat seal teeth, which contribute to the friction reduction or cancellation, can all play a sealing role.

In one embodiment, the gland block includes 8 seal teeth.

Specifically, in the air flow direction, the steam seal block sequentially includes a first long seal tooth 41, a second flat seal tooth 42, a third short seal tooth 43, a fourth short seal tooth 44, a fifth flat seal tooth 45, a sixth long seal tooth 46, a seventh long seal tooth 47, and an eighth long seal tooth 48.

Further, the boss 61 is opposite to the third short seal tooth 43 and the fourth short seal tooth 44. In other words, at the position of the blade tip without a boss, a flat seal tooth or a long seal tooth corresponds, and at the position of the blade tip with a boss, a short seal tooth corresponds, by which structure a plurality of seal cavities can be formed.

Through setting up a boss structure 61, can increase main damping, and then improve sealed rotor's stability.

Further, the vane is divided into a first portion and a second portion along a line perpendicular to the incoming flow direction of the air flow, and the boss 61 is provided on the top of the first portion of the vane. That is, the location of the boss 61 is upstream of the blade tip, and the stability of the sealing rotor is higher than if the location of the boss 61 is downstream of the blade.

In another embodiment, the seal teeth and the boss 61 have a gap therebetween, the gap having an axial height of 0.5-1.5 mm.

Preferably, there is a gap between the seal teeth and the boss 61, the axial height of the gap being 0.8 mm.

In another optional embodiment, the rotor is further provided with a prerotation piece, the prerotation piece is arranged in front of the airflow inlet, and the airflow inlet is a gap between the first sealing tooth and the boss along the airflow incoming flow direction; the typical inlet angle of the prerotation piece is 60 degrees and the outlet angle is 0 degree based on the inlet incoming flow angle. And the pre-rotation piece is additionally arranged, so that the cross rigidity can be reduced.

The key to the prewhirl is to install before sealing the inlet and the outlet angle is 0. The inlet angle of the prewhirl plate can also be 60 degrees; or the incoming flow angle, and the pre-rotation piece can be processed into a blade form, so that the complexity is low, and the loss is low.

In conclusion, the high-pressure turbine blade top steam seal structure provided by the invention can improve the stability of the sealed rotor by only arranging the boss structure at the top of the blade; meanwhile, the cross rigidity can be reduced by additionally arranging the prerotation piece with a typical inlet angle of 60 degrees and an outlet angle of 0 degree on the basis of an inlet incoming flow angle.

In the above embodiments of the present invention, the difference between the embodiments is mainly described, and different optimization features between the embodiments can be combined to form a better embodiment as long as they are not contradictory, and further description is omitted here in view of brevity of the text.

The above description is only an example of the present invention, and is not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.