JPS62233404A - Spring back pressure sealing device for steam turbine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to seal structures used between adjacent stationary parts of a turbine arrangement, and more particularly to seal structures used between adjacent stationary parts of a steam turbine. A particular application of the invention relates to a springback seal arrangement between the inside of a low pressure steam turbine, so as to minimize direct leakage of steam from one bleed region to the next region on the low pressure side. The purpose is to provide a seal between the cylindrical element and the fixed vane ring. This leakage of steam occurs so as to bypass the blade passage, and therefore has the effect of reducing thermodynamic efficiency.

The presence of asymmetric structural features such as ribs and horizontal joint flanges in the turbine inner cylindrical casing and the effective gradient of operating temperature across the LM Q create distortions in the cylindrical bearing surface in contact with the sealing device. This distortion results in a non-circular contact profile, with concomitant
The sealing surface rotates around a local tangential axis.

As an example of a conventional springback seal device, a multi-tooth device with an overall contact width of 43.2zz (1.7 inches) is known. If such distortions occur in the bearing surface, the normal advantages of reduced undulation due to multi-walled labyrinth seals are lost and an additional A secondary mixed passage is formed.

Another example of conventional sealing devices is also known as the flexible type, which consists of a thin sealing membrane that is rigidly positioned by a support circumferential stop on the outer cylindrical surface of an inner fixed cylindrical element. It consists of Opposed circumferences iR on the inner cylindrical surface of the outer fixation element prevent relative radial displacements between the inner and outer fixation elements (e.g. due to thermal expansion effects) due to the flexibility of the thin sealing membrane. To allow this, an interference fit for the outermost portion of the flexible seal is used as a part. A particular drawback of this sealing device is that it is difficult to properly insert the sealing membrane into the outer sleeve without damaging the mating surfaces and concomitantly reducing the effectiveness of the seal.

Other seal structures are disclosed in LeRoy D. McLoin et al. US Pat. No. 3,529,906.

New Year's Day LL The present invention provides a springback pressure seal device for a steam turbine. A steam turbine typically has a rotor and
a rotating blade attached to the rotor; an outer housing;
an inner wall attached to the outer housing for defining a plurality of pressure regions within the steam turbine. A first fixed cylindrical surface is disposed on the inner wall between a first relatively high pressure region and a second relatively low pressure region of the pressure regions. A fixed vane ring is attached to the inner wall. The fixed vane ring is aligned with and rests on the first fixed cylindrical surface.

A springback pressure seal device is a first
for substantially sealing a pressure region in the vicinity of the first fixed cylindrical surface from a second pressure region of relatively low pressure;
A compartmentalized seal ring comprises a plurality of seal ring segments. The fixed vane ring has a groove around its circumference and a notch near one side of the groove.

Each seal ring segment has a single central contact surface at its top for contacting the first fixed cylindrical surface.
It is growing. The central contact surface of the seal has a predetermined width that is less than the width of the remainder of the seal ring. A rib for engaging the first notch extends integrally from one side of the seal ring. A spring is disposed between the fixed vane near the bottom of the groove, the ring and each seal ring segment, and the spring extends along a narrow contact line along the center contact surface of each seal ring segment. Fixed contact face snoring now → To whistle 1 mya 11 to 11 bl +
Allowing relative radial displacements of the rail ring segments I, in areas of non-uniform distortion of the inner wall and the fixed vane ring, which occur as a result of structural asymmetries and thermal gradients between the inner wall and the fixed vane ring. Effectively reduces leakage flow to a minimum value.

According to one embodiment of the invention, each seal ring segment has chamfered edges on opposite sides of a single central contact surface. A first of the chamfered edges proximate the pressure area of relatively high pressure is located in the pressure area of relatively low pressure to provide a favorable pressure balance to maintain the sealing device in its designed sealing position. Preferably, the seal ring has a width less than the width of the adjacent chamfered edges, and the seal ring has a maximum radial height to cross-sectional width ratio ranging from about 2:1 to about 4=1. Preferably, the spring is a leaf spring having a loop member at one end thereof for mating with the ring seal segment adjacent to the second I;lJ notch.Seal device. The ratio of the radial height to the width of the cross section is preferably approximately 3 = 1, and the grooves are preferably two. The seal ring segment preferably includes a seal ring segment.

It is desirable to provide a predetermined clearance between the fixed vane ring and the seal ring segments adjacent to the sides of these grooves to allow axial movement of the seal ring segments.

Preferably, the rib protrudes integrally from near the midpoint of one side of the seal ring. The single contact surface of the seal ring preferably has a width of about 1/4 to 1/2 the width of the bottom surface of the seal ring.

According to yet another embodiment of the invention, the single central contact surface is not flat but rounded.

- T-Knee Care In FIG. 3, a springback pressure seal arrangement 10 for a steam turbine 12 is illustrated. The turbine 12 is
A rotor 14 and a rotating blade 1 attached to this rotor 14
6 and an outer housing 18.

An inner wall 20 of outer housing 18 is secured to outer housing 18 to define a plurality of pressure regions 22 within turbine 12 . The inner wall 20 has a pressure region 22
It has a first fixed cylindrical surface 24 disposed between a first pressure region 26 of the first pressure region 26 . As is well known in the art, a first pressure region 26 of the pressure regions is at a relatively high pressure and a second pressure region 26 is at a relatively high pressure.
The pressure region 28 is at relatively low pressure. Fixed vane ring 3
0 has a second fixed cylindrical surface 32 within a predetermined clearance 34 of the first fixed cylindrical surface 24 and in alignment with the first fixed cylindrical surface 24, as shown in FIG.

As discussed in the Background of the Invention section, various seals have been used in the past between fixed surfaces within steam turbines.

The labyrinth seal 36 shown in FIG. 1 is a form of prior art! It belongs to Nagi. This labyrinth seal has a number of tooth surfaces 38. However, it has been found that this particular configuration is susceptible to unwanted leakage between the pressure regions 22. Another prior art seal example is shown in FIG. The seal shown in FIG. 2 is a flexible seal 40. As shown in FIG. 2, the inner wall 20 of the outer housing 18 has a flow passage 42 formed around its circumferential surface. It has been found that this seal 40 is difficult to install, is easily damaged, and is therefore susceptible to loss of sealing effectiveness.

4, a springback pressure seal device 10 according to the present invention is illustrated. As shown in FIGS. 4 to 7, this springback pressure seal device 10 connects a relatively low pressure second pressure region 28 to a relatively high pressure first pressure region 26 to a first fixed cylindrical surface 24. The sealing device according to the present invention includes a sectioned seal ring 44 for substantially sealing in the vicinity of the turbine 12; be able to.

The segmented seal ring 44 includes a plurality of seal ring segments 46 . Fixed blade ringco; 0 is
It has a groove 48 around its circumference, and a first notch 50 near one side 52 of the tta 48. Each seal ring segment 46 has a single central contact surface 54 at the top that contacts the first fixed cylindrical surface 24 .

This central contact surface 54 is of a predetermined width, the magnitude of which is less than the smallest width of the remainder of the seal ring segment 46 . The center contact surface 54 of the seal ring segment 46 is connected to the side surface 56 of the seal ring segment 46.
a, 56b are arranged at right angles. The rib 58 is the first
integrally protrudes from one side 56b of the seal ring segment 46 to engage the notch 50 of the seal ring segment 46.

A spring device 60 is disposed between the bottom 62 of the groove 48 and each of the seal ring segments 46. Spring device 6
0 can be, for example, a leaf spring 64 or :1 as is well known in the art.
A spring device 60 , which may be a coil spring, engages the single central contact surface 54 of each seal ring segment 46 to the first fixed cylindrical surface 24 along a narrow contact line 55 and connects the first notch 50 . The ribs 58 refer to the inner wall 20 and the fixed blade ring 30.
Relative radial displacement of seal ring segments 46 to effectively minimize leakage flow in areas of non-uniform distortion of fixed vane ring 30 and inner wall 20 resulting from thermal gradients and structural asymmetries of allow to do so.

In the embodiment shown in FIGS. 4-8, each seal ring segment 46 has a chamfered edge 66a, a Bob
(See Figure 6). The first chamfered edge 66a adjacent to the first pressure area 26 of relatively high pressure has a second chamfered edge 66 adjacent to the second pressure area 28 of relatively low pressure.
The seal ring segment 46 according to the invention has a width in the range 1:4 to 1:1 of the width of b.
: has a radial height to maximum cross-sectional width ratio ranging from 1 to about 421. Each seal ring segment 46 preferably has a second notch 70 in its bottom 72 (eighth
), the leaf spring 64 has a loop member 74 for engaging the seal ring segment 46 in the vicinity of the second notch 70 .

Preferably, the radial height to cross-sectional width ratio of seal ring segment 46 is equal to about 3:1. 1h48
preferably includes two sections 76m and 76b. For example, each seal ring has seven (1176a, 76
24 seal ring segments 46 each having an arc length of 15° in b. Preferably, the rib 58 integrally projects from approximately the midpoint 58 (FIG. 4) of one side 56b of the seal ring segment 46.

According to the variant embodiment shown in FIG.
has a rounded central contact surface 54.

The cross-sectional shape of the seal ring of the invention forms a single narrow line of contact with the first fixed cylindrical surface. Additionally, the height and width parameters of the cross section are important when maintaining contact bearing pressure.
The balance of pressures overcomes frictional effects and increases the stability of each seal ring segment 46 in resisting displacement of the sealing device 10 from its design position in uniform contact with the downstream side 52 of the groove 48 and the downstream side 52 of the groove 48. It's about the size you want it to be. The stability of the seal is determined by the radial height to axial width ratio and the chamfered edges 66a, 6 proximate the single central contact surface 54.
Depending on the size of 6b, the pressure seal device 10 according to the invention is configured to allow relative axial and radial displacement between the fixing elements.

If the fixed vane ring 30 and the inner wall 20 are not rotationally aligned, the contact between the seal and the first fixed cylindrical surface may be a point contact.

[Brief explanation of drawings]

1 is a side cross-sectional view of a prior art labyrinth seal; FIG. 2 is a side cross-sectional view of a prior art flexible seal; FIG. 3 is a side cross-sectional view of a portion of a steam turbine; and FIG. , an enlarged side sectional view of the interior portion of FIG. 3 showing the sealing device according to the invention during operation of a steam turbine; FIG. and a side cross-sectional view of a sealing device having a flat central contact surface; FIG. 6 is a side view showing a seal ring segment; FIG. FIG. 8 is an enlarged cross-sectional view of the inner portion B in FIG. 7, and FIG. 9 is a side cross-sectional view of a sealing device having a rounded central contact surface. 10...Springback pressure seal device 12...
Steam turbine 14... Rotor 16... Rotating vane 18... Outer housing 20... Inner wall 22... Multiple pressure regions 24... First fixed cylindrical surface 26... First pressure Area 28...
Second pressure area 30...Fixed vane ring 32...
・Second fixed cylindrical surface 34...predetermined clearance 44
Seal ring 48 Groove 46 Seal ring segment 50 First notch 52 One side of groove 54 Single central contact surface 55 Narrow contact Line 50b...one side 58 of the seal ring segment
...Rib 60...Spring applicant Westinghouse Elec FIG, 3

Claims (1)

[Scope of Claims] A rotor, a rotating blade attached to the rotor, an outer housing, an inner wall attached to the outer housing and defining a plurality of pressure regions inside a steam turbine, and the inner wall. a fixed vane ring attached to the inner wall, the surface of the inner wall being disposed between a first relatively high pressure region and a relatively low second pressure region of the pressure regions. a first fixed cylindrical surface; the fixed vane ring has a second fixed cylindrical surface aligned with the first fixed cylindrical surface and within a predetermined clearance of the first fixed cylindrical surface; A turbine springback pressure sealing arrangement for substantially sealing the first pressure region of relatively high pressure from the second pressure region of relatively low pressure in the vicinity of the first fixed cylindrical surface. , a segmented seal ring comprised of a plurality of seal ring segments, the fixed vane ring including a groove around its circumference;
said groove includes a first notch near one side thereof, and each of said seal ring segments has a single central contact surface of a predetermined width at its top for contacting said first fixed cylindrical surface. wherein the single central contact surface has a width less than a minimum width of the remainder of the seal ring;
A rib integrally projects from one side of the seal ring segment to engage the first notch, and a spring is provided between the stationary vane ring and each of the seal ring segments near the bottom of the groove. the spring is arranged to engage the single central contact surface of each of the seal ring segments with the first fixed cylindrical surface along a narrow line of contact and to engage the first fixed cylindrical surface along a narrow line of contact; and the ribs allow for relative radial displacement of the seal ring segments, and the alignment between the inner wall and the fixed vane ring may occur as a result of structural asymmetries and thermal gradients between the inner wall and the fixed vane ring. A springback pressure sealing system for a steam turbine, characterized in that it effectively minimizes leakage flow in areas of unequal strain.