WO1997001020A1

WO1997001020A1 - Axially sliding steam turbine valve

Info

Publication number: WO1997001020A1
Application number: PCT/DE1996/001011
Authority: WO
Inventors: Dieter MÜRBE
Original assignee: Siemens Aktiengesellschaft
Priority date: 1995-06-20
Filing date: 1996-06-10
Publication date: 1997-01-09
Also published as: JPH11508014A; IN189232B; JP3889809B2; EP0834002A1; EP0834002B1; DE19522359C1; DE59607540D1

Abstract

The invention pertains to a steam turbine component with a principal axis (1) and a dividing element (3) which is positioned at right angles to the principal axis (1) in a cross-sectional face (2) to complete the latter and provided with at least one through-duct (4) through which steam can pass. Also provided is a choke element capable of sliding essentially along the principal axis (1) and serving to regulate the steam flow through the through-duct (4). The choke element has a first sealing surface (6) and a second sealing surface (7). The sealing surfaces (6, 7), when in a position which occludes the through-duct, are in sealing contact with the dividing element (3) and are separated from the latter when in a position which at least partially opens the through-duct. Each sealing surface (6, 7) lies in its respective cross-sectional plane which is perpendicular to the principal axis (1), reducing the friction forces to be overcome when the through channel (4) is opened and ensuring a good seal.

Description

description

AXIAL SLIDING STEAM TURBINE VALVE

The invention relates to a steam turbine component and a steam turbine with a throttle element which can be displaced essentially along a main axis, in particular the main axis of the turbine, for regulating the steam flow through a flow passage which is provided in a separating element which extends in a direction perpendicular to the main axis Cross-sectional area this is arranged to fill. The invention further relates to a method for regulating the steam flow in a steam turbine with a throttle element.

Various regulating devices are known for regulating the steam flow in a steam turbine. In the article "The rotary slide valve as a regulating element for extraction steam turbines" by K.

Speicher and E. Mietεch, Maschinenbautechnik, Berlin, Volume 15, Issue 4, 1966, pages 185 to 190, describe a comparison of control elements based on valves and rotary valves. Another control device is known from the document DE-A-1 426 792.

Axial and radial flow slides are mentioned as possible forms of rotary slides. The slides are used to completely or partially block openings that run in a cross-section of the steam turbine

Nozzle covers are provided. A first form of a slide consists of a ring which can be rotated in the circumferential direction and which has openings analogous to the openings of the nozzle cover and through which axial flow flows, the openings of the slide being flowed through in the axial direction, ie in the direction of the main axis of the steam turbine. In a second form, a rotatable ring is also provided, which, however, has a radial shape. is flowed through direction, for this purpose the openings in the nozzle cover cause a deflection of the flow from the radial to the axial direction. The slide lies here over a large area on a corresponding deflection part of the nozzle cover. A movement of the slide must therefore take place against considerable frictional resistance. In a third embodiment radially displaceable ring segments are provided, by means of which the openings in the nozzle cover can be closed. As a fourth embodiment, a slider with a radial flow and an axially displaceable ring is described, the nozzle cover here in turn having a flow deflecting stem on which the axially displaceable ring is guided. In this case, too, there is the problem of large frictional forces which have to be overcome. With the radial rotary valves mentioned, complete static relief is possible with throttle control, but a relatively large radial gap must be provided to ensure free thermal expansion. As a result, it is not possible to completely close the opening of the nozzle cover, so that loss of liquidity due to undesired steam flow has to be accepted.

When the known rotary rotary valves are used, large contact and frictional forces arise which lead to corresponding wear of the parts sliding on one another. Large actuators must also be provided for the operation of such axial rotary valves. To reduce the contact forces, complicated and complex designs with relief surfaces are known. However, these require a corresponding space requirement in the radial direction. These constructions are therefore practically not applicable to turbines with overpressure construction. Because of the known disadvantages, rotary valves are currently used at most at relatively low extraction steam pressures. It is therefore the object of the invention to provide a steam turbine component with a throttle element for regulating the steam flow, the throttle program being suitable for use in a turbine for high extraction steam pressures.

According to the invention, the object aimed at a steam turbine component is achieved in that a separating element which is arranged to fill in a cross-sectional area running perpendicular to the main axis of the steam turbine component and which has at least one flow passage for the flow of steam and one along the main axis displaceable throttle element for regulating the steam flow through the flow passage are provided, the throttle element having a first sealing surface and a second

Has sealing surface, and in a position closing the flow passage, the sealing surfaces lie sealingly against the separating element and in a position at least partially opening the flow passage, the sealing surfaces are spaced from the separating element. The separating element has a flow passage which is stretched away from the cross-sectional area along the main axis and has a wall which is essentially parallel to the cross-sectional area and is spaced apart from it. The first sealing surface bears against this wall at a position of the throttle element which closes the flow passage. In the position closing the flow passage, the second sealing surface also lies in the cross-sectional area on the separating element.

Through a throttle element, which is axially displaceable and in a position closing the flow passage of the separating element, in particular εt this is an annular opening with interposed webs in a nozzle cover, the separating element is in contact with each other and the flow passage partly or partially is completely open position from the separating element, the disadvantages known rotary valve avoided. In particular, the wear due to frictional contact with the separating element is avoided, the flow passage is completely shut off or, in the case of several flow passages, the latter is completely closed, as a result of which undesirable losses in steam flow are avoided. By avoiding frictional contacts with the separating element, large actuators are also not necessary. When the steam turbine component is used in a steam turbine, in particular in the low-pressure part of the steam turbine, the main axis of the steam turbine component coincides with the main axis of the steam turbine.

Because the flow passage is stretched in the axial direction from the cross-sectional area and has a wall running parallel to the cross-sectional area, the flow is deflected in the flow passage from a radial direction into an axial direction. The flow passage is blocked by the throttle element at the end of the flow passage in which the flow runs radially. When the flow passage is closed, a definite frictional connection can be achieved in which, for example, the throttle element is pressed into the position closing the flow passage by means of a low residual steam force.

By designing the flow passages with a flow formation in the axial direction or with a deflection in the radial direction, an arrangement of the sealing surfaces which is respectively adapted to this takes place. In a flow passage having a purely axial flow, both sealing surfaces are preference, directly to the separating element in the Querschnitt¬ sebene ^'to. In the case of a flow passage, which also requires a radial flow of the steam, the first sealing surface is preferably in contact with the above-mentioned wall and the second sealing surface is in direct contact with the separating element in the cross-sectional area. The sealing surfaces are preferably designed as thin-walled circular rings. As a result, the sealing surface is quasi linear, so that essentially no friction

REPLACEMENT BLADE (RULE 26) there are contacts with the separating element, but a high level of tightness is nevertheless achieved.

Preferably, the throttle body is therefore a circular double seat ring, which is arranged centrally to the main axis. The central arrangement means that the center point of the circular ring, when viewed in a cross section, coincides with the main axis. A simple manufacture of the guides of a rotating ring displacing the double seat ring and the separating element in a turbine housing is thus achieved. In particular with a view to simple assembly, the double seat ring is composed of two semicircular segments. However, it is also conceivable to assemble the double seat ring from several circular segments. The double seat ring preferably has an axial extent which corresponds to the axial extent of the flow passage, and radially elongated webs on which the sealing surfaces are arranged. ^'This leaks εind largely avoided depending on the steam temperature.

At least two, in particular three, guide grooves running parallel to the main axis are provided for an exact guidance of the dosing element, in which preferably two guide bolts each engage, which are fastened to the housing of the turbine. By means of these guide bolts, which engage in the guide grooves, a central, exact alignment of the throttle element can be achieved, and the throttle element can be guided largely without play during an axial movement.

The guide bolts are preferably eccentric bolts. An eccentric bolt has, for example, two solid cylinders with a circular cross section, each of which is stretched along an axis and is firmly connected to one another at adjacent end faces. The direction of the axes are identical, only one solid cylinder being offset relative to the other, ie being arranged eccentrically. As a result, an exact guidance of the throttle element in reached the turbine housing, whereby, for example, manufacturing tolerances can also be compensated.

The throttle element preferably has at least one displacement groove, in particular three displacement grooves, which is both in the axial direction and in the circumferential direction, i.e. runs diagonally to the main axis. A rotary ring which rotates in the circumferential direction, in particular via a control pin, preferably engages in this displacement groove. When the rotary ring is rotated in the circumferential direction, the rotary movement of the rotary ring converts into an axial movement of the throttle element due to the displacement groove oriented obliquely to the main axis. As a result, the throttle element is displaced in the axial direction in a simple manner and with the use of only slight forces.

The steam turbine component with the dosing element is preferably used in a steam turbine, in particular in a steam turbine with a high extraction steam pressure.

The steam turbine with a displaceable throttle element and the method for regulating the steam throughput in a steam turbine are explained in more detail using the schematic examples shown in the drawing. Show it:

1 shows a longitudinal section through a steam turbine with a

2 shows a plan view of the throttling element according to FIG. 1 and FIG. 3 shows a cross section of the steam turbine according to FIG. 1.

1 shows a section of a steam turbine in a longitudinal section at the beginning of the low-pressure part in front of the area of the low-pressure blading. The steam turbine, which is rotationally symmetrical about a main axis 1, has a turbine housing 9 which surrounds the turbine rotor 17. The cross-sectional area 2 of the steam turbine between the turbine rotor 17 and turbine housing 9 is filled by a separating element 3, a so-called window ring. The separating element 3 has a flow passage 4, which is formed from an annular opening 18 with intermediate webs in the separating element 3, a sleeve 16 extended in the direction of the main axis 1 and an annular wall 8. The sleeve 16 is directly on the separating element 3 in the vicinity of the opening 18, on the side facing the turbine rotor 17. The annular wall 8 is tightly connected to the sleeve 16 and lies on the side of the sleeve 16 facing away from the turbine rotor 17. The wall 8 is thus in the form of an annular collar on the sleeve 16, so that one of the separating element 8 runs parallel to it spaced surface is formed. Häuεe intermediate flow passage 4 and Turbinenge- 9 is an axially displaceable ^Dros' selorgan 5 assigns ange¬.

Guide bolts 11a, 11b are fastened in the turbine housing 9 and are each stretched in a plane perpendicular to the main axis 1. At least three pairs of the guide bolts 11a, 11b are attached to the circumference of the turbine housing 9. The illustrated guide bolts 11a, 11b are offset against one another, so that they each engage in a corresponding groove 10a, 10b of the dosing element 5. The throttle member 5 has a throttle sleeve 19 extending along the main axis 1 and two spaced-apart circular webs 20a, 20b, which are attached to the side of the throttle sleeve 19 facing the turbine rotor 17 and are stretched from there to the main axis 1. The throttle element 5 can be displaced in the direction of the main axis 1, ie in the axial direction, via a rotating ring 13 running on the circumference of the turbine housing 9. Throttle lugs 21a, 21b, which extend in the axial direction towards the separating element 3, act on the webs 20a, 20b. The throttle nose 20a forms a first annular sealing surface 6 and the throttle nose 21b forms a second annular sealing surface 7. The first sealing surface 6 lies against the wall 8 and the second sealing surface 7 directly on the separating element 3 in a region between the turbine housing 9 and the opening 18. As a result, the flow path 4 is sealed. On the wall 8 and on the separating element 3 there is in each case attached a sleeve-like drose collar 15a, 15b which is directed away from the cross-sectional area 2 in the axial direction. The throttle lugs 21a, 21b of the throttle element 5 and the throttle collars 15a, 15b assigned to the flow passage 4 thus lie directly one above the other. As a result, the ratio between the steam throughput and the stroke performed along the main axis 1 of the throttling process 5 can be predetermined. In particular, a linearization of the relationship between steam throughput and stroke of the dosing element can be achieved. In FIG 1, the Drosεelorgan 5 is illustrated additionally by dashed lines in the subscribed Poεition, in which the first Dicht¬ surface 6 and the second sealing surface 7 each dung from the Wan¬ ^'8 and the separation element are beabεtandet 3, so that the flow passage 4 is at least partially released for a flow of steam. The throttle element 5 is displaced in the axial direction by the rotary ring 13, so that the steam throughput through the separating element 3 can be regulated from a complete closure of the flow passages 4 to a complete opening of the flow passages 4. By suspending the throttle element 5 via guide bolts 11a, 11b guided in grooves 10a, 10b, a central, ie symmetrical suspension of the throttle element 5, which is symmetrical with the main axis 1, as well as free thermal expansion is ensured. The size of the first sealing surface 6 and the second sealing surface 7, as well as the height of the webs 20a, 20b, ie the radial expansion of the dosing element 5, are largely freely selectable, so that even a complete relief of steam forces is possible. To simplify the assembly, both the separating element 3 with the flow passage 4, the rotating ring 13 and the throttle element 5 are composed of respectively suitable semicircular segments. FIG. 2 shows a top view of a throttle body 5 as described in FIG. 1 and designed as a double seat ring 5a. The double seat ring 5a has three pairs of guide grooves 10a, 10b, each of which is directed along the main axis 1, ie in the axial direction. The pairs of guide grooves 10a, 10b are distributed symmetrically over the circumference of the double seat ring 5a, only one pair being shown for the sake of clarity. A displacement groove 12 is provided between the guide grooves 10a, 10b and runs obliquely with respect to the main axis 1. A total of three displacement grooves 12 are provided over the circumference. The guide grooves 10a, 10b serve to suspend the throttle member 5a via respective guide bolts 11a, 11b, which engage in the guide grooves 10a, 10b and are fastened in the turbine housing 9. As shown in FIG. 3, the guide bolts 11a, 11b are designed as eccentric bolts, whereby an exact alignment of the double seat ring 5a with the main axis 1 is achieved. A rotary ring 13 extending on the circumference of the turbine housing 9 engages in the displacement grooves 12, so that a rotation of the rotary ring 13 in the axial direction is achieved by rotating the rotary ring 13.

3 shows a section of the steam turbine according to FIG. 1 in a cross section, in which a guide pin 11a designed as an eccentric pin, the rotating ring 13, the throttle element 5

(the double seat ring 5a) and a drive 14 for the rotary ring 13 are shown.

The rotating ring 13 has control bolts 22 which are elongated in the radial direction and which desε in respective displacement grooves 12

Intervene Droεεelorganε 5. Preferably, three pairs of guide bolts 11a, 11b and a corresponding number of guide grooves 10a, 10b and displacement grooves 12 are provided in the circumferential direction.

The invention is characterized by an axially displaceable throttle element, which is connected via two sealing surfaces. Chen, which in each case seal off at two spaced-apart boundary walls of a flow passage running in the cross-sectional direction of a steam turbine. The sealing surfaces are designed such that almost no frictional forces can be overcome when the throttle element opens the flow passage. The throttle element can be moved by heat via several guide bolts and is suspended centrally to the main axis of the steam turbine. A displacement of the throttle element in the direction of the main axis can be achieved via the displacement grooves running obliquely to the main axis on the circumference of the throttle element. This takes place via a rotating ring which can be rotated in the circumferential direction and which has at least one, preferably three, control bolts which engage in a corresponding displacement groove. The throttle member is vorzugsweiεe for an arbitrarily adjustable Drosεelung of Dampfεtrömen by annular and concentric to the axis Turbinen¬ ^'openings arranged in front of the low-pressure part of the steam turbine. It is particularly suitable for overpressure turbines and for high extraction steam pressures.

Claims

claims

1. steam turbine component with a main axis (1), a separating element (3), which is arranged in a cross-sectional area (2) filling this perpendicular to the main axis (1) and has at least one flow passage (4) for the flow of steam, and with an im throttle element (5) which is displaceable along the main axis (1) for regulating the steam flow through the flow passage (4), the throttle element (5) having a first sealing surface (6) and a second sealing surface (7), one of which has the In the position in which the flow passage (4) closes, the sealing surfaces (6, 7) lie sealingly on the separating element (3) and in a position which at least partially opens the flow passage (4), the sealing surfaces (6, 7) are spaced apart from the separating element (3), wherein the

Flow passage (4) is stretched from the cross-sectional area (2) along the main axis (1) and has a wall (8) which runs essentially parallel to the cross-sectional area (2) and at a distance from it, at which position in the position closing the flow passage (4) the first sealing surface (6) rests, and in the position closing the flow passage (4) the second sealing surface (7) rests directly on the separating element (3) in the cross-sectional plane (2).

2. Steam turbine component according to claim 1, d a d u r c h g e k e n n z e i c h n e t that daε Droεselorgan (5) iεt a circular double seat ring (5a), which is arranged centrally to the main axis.

3. Steam turbine component according to claim 1 or 2, characterized in that the double seat ring (5a) from two semicircular segments (5b, 5c) is put together.

4. Steam turbine component according to one of the preceding claims with a housing (9), characterized in that the duct element (5) has at least two guide grooves (10a, 10b) running parallel to the main axis (1), each of which has at least one guide bolt (lla, Ilb) intervene, which is attached to the housing (9).

5. Steam turbine component according to claim 4, so that the guide bolts (Ila, Ilb) are eccentric bolts.

6. Steam turbine component according to one of the preceding claims, that because of the fact that the throttle element (5) has at least one displacement groove (12) which is both stretched in the circumferential direction and also in the direction of the main axis (1).

7. Steam turbine component according to Claim 4, so that a rotating ring (13) which engages in the displacement groove (12) and which engages in the displacement groove (12) is provided, which causes a displacement of the doses element (1) in the direction of the main axis (1) by rotation in the circumferential direction.

8. Steam turbine component according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that at least one of the sealing surfaces (6, 7) is designed as a thin-walled circular ring.

9. Steam turbine with a steam turbine component according to one of the preceding claims.