JP3889809B2 - Steam turbine component with throttle mechanism for adjusting steam flow and method for adjusting steam flow in a steam turbine - Google Patents

Description

The present invention relates to a steam turbine component and a main shaft for adjusting a steam flow rate through a flow path provided in a partition wall element that is disposed so as to close this surface in a cross section extending perpendicularly to the main shaft. More particularly, the present invention relates to a steam turbine provided with a throttle mechanism that can move along a main shaft of the turbine. The present invention further relates to a method for adjusting a steam flow rate in a steam turbine with a throttle mechanism.
Various regulators are known for regulating the steam flow in a steam turbine. The publication “Maschienenbautechnik” published in 1966, Berlin, Vol. 15, No. 4, pp. 185-190, paper by K. Speicher and E. Mietsch, A rotary valve as a regulating device (Der Drehschiber als Regelorgan fuer Entnahme-Dampfturbinen) describes a comparison of the regulating mechanism based on the valve and the rotary valve. Another adjustment mechanism is known from DE 1426792 A1.
Possible types of rotary valves include slide valves that flow axially and radially. This slide valve is used to completely or partially close the opening provided in the nozzle cover extending across the cross section of the steam turbine. The first type of slide valve consists of a circumferentially rotatable ring, which has an opening similar to the opening of the nozzle cover and flows through in the axial direction, with the opening of the slide valve in the axial direction. That is, it flows through in the direction of the main axis of the steam turbine. The second type is also provided with a rotatable ring, which is flowed through in particular in the radial direction, so that the opening in the nozzle cover diverts the flow from the radial direction to the axial direction. The slide valve in this case is in contact with the corresponding flow turning part of the nozzle cover in a large area. Therefore, the movement of this slide valve must be carried out against a considerably large frictional resistance. In the third type, a radially movable ring segment is provided that can close the opening in the nozzle cover. A fourth type includes a slide valve that is provided with an axially movable ring and flows radially, wherein the nozzle cover also has a front structure that redirects the flow. A ring is guided which is movable axially on the structure. Even in this case, there is a problem that the frictional force to be overcome is large. In the case of the above-mentioned radial type rotary valve, it is possible to reduce the load completely statically when adjusting the throttle, but it is necessary to provide a relatively large radial gap to ensure free thermal expansion. There is. This makes it impossible to completely close the nozzle cover opening, so that wasteful losses due to undesired steam flow must be accepted.
When using known axial rotary valves, large pressing forces and frictional forces are generated, which cause corresponding wear on the parts that slide relative to each other. In order to operate this type of axial rotary valve, a larger adjusting drive must be prepared. In order to reduce this pressing force, a complicated and expensive structure having a gentle pressure surface is known. However, this requires a corresponding space requirement in the radial direction. Therefore, this structure is not practically available in reaction turbines. Based on this known drawback, rotary valves are currently employed only for relatively low extraction vapor pressures.
An object of the present invention is to provide a steam turbine component with a throttle mechanism for adjusting the steam flow rate so that the throttle program employed in the turbine is suitable for high extraction steam pressure.
An object directed to a steam turbine component is according to the invention at least one flow path arranged in a cross-section extending perpendicular to the main axis of the steam turbine component, closing this surface and through which steam flows. And a throttle mechanism that is movable along a main shaft for adjusting the flow rate of steam passing through the flow path. The throttle mechanism has a first seal surface and a second seal surface. The sealing surface is hermetically abutted against the partition element at a position where the flow path is closed, and the sealing surface is separated from the partition element at a position where the flow path is at least partially opened. In this case, the partition element comprises a channel extending along the main axis in a direction away from the cross section, which channel extends substantially parallel to the cross section and has a wall separated therefrom. The first sealing surface comes into contact with the wall at a position where the flow path is closed. Furthermore, the second sealing surface abuts against the partition element in the cross section at a position where the flow path is closed.
In particular, when the partition element is a ring-shaped opening that is finely partitioned by a cross piece in the nozzle cover, in the position where the flow path of the partition element is closed, there is another contact that abuts the partition element and partially or completely opens the flow path The disadvantage of the known rotary valve is avoided by a throttle mechanism that is axially movable in position away from the bulkhead element. In particular, wear due to frictional contact with the bulkhead element is avoided and complete closure of the flow paths is achieved, or in the case of multiple flow paths, their complete closure is achieved, which results in an undesirable loss of vapor flow Can be avoided. By avoiding frictional contact with the bulkhead element, a similarly large adjustment drive is not required. When such a steam turbine component is employed in a steam turbine, particularly in the low pressure portion of the steam turbine, the main axis of the steam turbine component coincides with the main axis of the steam turbine.
Since the flow path extends in the axial direction from the cross section and has a wall extending parallel to the cross section, the flow is turned from the radial direction to the axial direction in the flow path. The blocking of the flow path by the throttle mechanism is performed at the end of the flow path where the flow is directed in the radial direction. When the flow path is closed, for example, the throttle mechanism is pressed to a position where the flow path is closed by a slight residual vapor pressure, so that a reliable frictional coupling is obtained.
By configuring the flow channel with a flow shape in the axial direction or with a turning in the radial direction, an arrangement of the sealing surfaces suitable for this can be obtained. In the case of a flow channel that flows purely in the axial direction, both sealing surfaces abut directly on the partition element, in particular in cross section. In the case of a flow path which also causes a radial flow of steam, preferably the first sealing surface abuts the aforementioned wall and the second sealing surface abuts directly on the septum element in cross section. The sealing surface is preferably formed as a thin annular ring. As a result, the sealing surface has a quasi-linear shape, so that almost no frictional contact with the partition wall element occurs, and nevertheless high airtightness is obtained.
It is therefore advantageous if the throttle mechanism is a circular double seat ring arranged concentrically with respect to the main shaft. The concentric arrangement means that the center of the ring coincides with the main axis in the cross section. This makes it possible to easily manufacture the rotating ring that moves the double seat ring and the guide part of the partition element in the turbine housing. In order to simplify the assembly in particular, the double seat ring consists of two semicircular segments. However, it is conceivable that the double seat ring is composed of a plurality of circular segments. The double seat ring has in particular an axial extent corresponding to the axial extent of the flow path and a radially extending web in which a sealing surface is arranged. This largely avoids non-hermeticity related to steam temperature.
In order to accurately guide the throttle mechanism, there are preferably at least two, in particular three guide grooves, each extending parallel to the main shaft, preferably fitted with two guide bolts, each fixed to the turbine housing. It is done. The guide bolts that fit into these guide grooves allow the throttle mechanism to be properly centered and aligned, and the throttle mechanism is guided with little play when moving axially.
The guide bolt is advantageously an eccentric bolt. The eccentric bolt has, for example, two solid cylinders with circular cross-sections that extend along their respective axes and are firmly connected to each other at their adjacent end faces. The directions of these axes are then the same, provided that one solid cylinder is offset relative to the other solid cylinder, i.e. arranged eccentrically. As a result, the throttle mechanism can be guided accurately in the turbine housing, which can compensate for manufacturing tolerances, for example.
The throttle mechanism preferably has at least one, in particular three sliding guide grooves, extending in the axial direction as well as in the circumferential direction, ie extending obliquely with respect to the main axis. A single rotating ring, preferably rotating in the circumferential direction, is engaged in this sliding guide groove, in particular via a control bolt. When the rotating ring rotates in the circumferential direction, the rotating motion of the rotating ring is converted into the axial motion of the diaphragm mechanism based on the sliding guide groove extending inclined with respect to the main shaft. As a result, the diaphragm mechanism can be easily moved in the axial direction with very little force.
Preferably such a steam turbine component with a throttling mechanism is used in a steam turbine, in particular a steam turbine with a high extraction steam pressure.
A steam turbine with a movable throttle mechanism and a method for adjusting the steam flow in the steam turbine will be described in detail with reference to the embodiments schematically shown in the drawings.
FIG. 1 is a longitudinal sectional view of a steam turbine with a throttle mechanism,
2 is a plan view of the throttle mechanism in FIG. 1, and FIG. 3 is a cross-sectional view of the steam turbine in FIG.
In FIG. 1, the front of the range of the low-pressure blade row at the tip of the low-pressure part of the steam turbine is shown in a sectional view. A rotationally symmetric steam turbine about the main shaft 1 has a turbine housing 9 surrounding a turbine runner 17. The cross section 2 between the turbine runner 17 and the turbine housing 9 in the steam turbine is closed by a partition element 3, a so-called ring with window. The partition element 3 has a flow path 4. This flow path is formed by an annular opening 18 partitioned by a cross piece in the partition wall element 3, a sleeve 16 extending in the direction of the main shaft 1, and an annular wall 8. The sleeve 16 is secured to the partition element 3 around the opening 18 directly on the turbine runner 17 side. The annular wall 8 is located on the opposite side of the sleeve 16 from the turbine runner 17 and is hermetically coupled to the sleeve 16. The wall 8 is therefore provided on the sleeve 16 in the form of an annular flange, so that a surface is formed which extends parallel to the partition element 3 and is spaced therefrom. A throttle mechanism 5 that is movable in the axial direction is disposed between the flow path 4 and the turbine housing 9.
Guide bolts 11 a and 11 b extending in a plane perpendicular to the main shaft 1 are attached to the turbine housing 9. At least three pairs of guide bolts 11a and 11b are attached to the periphery of the turbine housing 9, respectively. The illustrated guide bolts 11a and 11b are offset from each other so that they fit into the corresponding guide grooves 10a and 10b of the throttle mechanism 5, respectively. The throttle mechanism 5 has a throttle sleeve 19 extending along the main shaft 1 and annular flanges 20a, 20b on both sides spaced from each other. These flanges are fixed to the turbine runner 17 side of the throttle sleeve 19, Extending toward the main shaft 1. The throttle mechanism 5 can move in the direction of the main shaft 1, that is, in the axial direction, via a rotating ring 13 extending along the periphery of the turbine housing 9. On the flanges 20a and 20b, throttle noses 21a and 21b extending in the axial direction toward the partition wall element 3 are fixed. The throttle cylinder 21 a forms a first annular seal surface 6, and the throttle nose 21 b forms a second annular seal surface 7. The first sealing surface 6 abuts against the wall 8 and the second sealing surface 7 abuts directly against the partition element 3 in the area between the turbine housing 9 and the opening 18. As a result, an airtight chain of the flow path 4 is achieved. Bush-shaped aperture collars 15a and 15b are fixed to the wall 8 and the partition wall element 3, respectively, and are oriented away from the cross section 2 in the axial direction. The diaphragm noses 21a and 21b of the diaphragm mechanism 5 and the diaphragm collars 15a and 15b attached to the flow path 4 are therefore directly above and below each other. Thereby, the relationship between the steam flow rate and the stroke of the throttle mechanism 5 implemented along the main shaft 1 can be defined in advance. In particular, linearity is obtained in the relationship between the steam flow rate and the stroke of the throttle mechanism. In FIG. 1, the throttle mechanism 5 assists in that the first sealing surface 6 and the second sealing surface 7 are separated from the wall 8 or the partition element 3, respectively, so that the flow path 4 for the flow of steam is at least partially opened. This state is indicated by a broken line. Since the throttle mechanism 5 is moved in the axial direction by the rotating ring 13, the steam flow rate passing through the partition wall element 3 can be adjusted from the complete closing of the flow path 4 to the full opening of the flow path 4. By suspending the throttle mechanism 5 via the guide bolts 11a and 11b guided by the guide grooves 10a and 10b, the throttle mechanism 5 can be centered, that is, suspended symmetrically with respect to the main shaft 1. And its free thermal expansion is guaranteed. Since the size of the first sealing surface 6 and the second sealing surface 7 and the height of the flanges 20a, 20b, ie the radial extent of the throttle mechanism 5, can be chosen quite freely, it is possible to completely release the steam force. it can. In order to simplify the assembly, the partition element 3 with the flow path 4, the rotary ring 13 and the throttle mechanism 5 are each composed of semi-circular segments that are closely aligned.
FIG. 2 is a plan view showing the diaphragm mechanism 5 formed as the double seat ring 5a as described in FIG. The double seat ring 5a has three pairs of guide grooves 10a and 10b extending along the main shaft 1, that is, in the axial direction. Each pair of guide grooves 10a, 10b is distributed symmetrically over the circumferential surface of the double seat ring 5a, and only a pair of guide grooves are shown here for the sake of simplicity. Between the guide grooves 10a and 10b, a sliding guide groove 12 extending obliquely with respect to the main shaft 1 is provided. A total of three sliding guide grooves 12 are provided over the circumferential surface. The guide grooves 10a and 10b are used to suspend the throttle mechanism 5a via guide bolts 11a and 11b fitted in these and attached to the turbine housing 9. The guide bolts 11 a and 11 b are formed as eccentric bolts as shown in FIG. 3, whereby the double seat ring 5 a can be accurately aligned with the main shaft 1. Since the rotating ring 13 that moves along the circumferential surface of the turbine housing 9 is engaged with the sliding guide groove 12, the throttle mechanism 5 can be moved in the axial direction by the rotation of the rotating ring 13.
FIG. 3 shows a cross-sectional view of the steam turbine in FIG. 1, in which the guide bolt 11 a formed as an eccentric bolt, the rotary ring 13, the throttle mechanism 5 (double seat ring 5 a) and the drive for the rotary ring 13 Device 14 is shown.
The rotating ring 13 has a control bolt 22 that extends in the radial direction and engages with the sliding guide groove 12 of the throttle mechanism 5. In particular, in the circumferential direction, three pairs of guide bolts 11a and 11b and the same number of guide grooves 10a and 10b and sliding guide grooves 12 are provided.
The present invention provides an axially movable throttling mechanism that provides two sealing surfaces that hermetically close the flow path at two spaced apart boundary walls extending in the cross-sectional direction of the steam turbine of the flow path. Characterized. The sealing surface is designed so that little frictional force needs to be overcome during movement of the throttle mechanism that opens the flow path. The throttle mechanism can be thermally moved through a plurality of guide bolts and is concentrically suspended with respect to the main shaft of the steam turbine. The diaphragm mechanism can move in the direction of the main shaft through a sliding guide groove that extends at an inclination with respect to the main shaft on the circumferential surface of the diaphragm mechanism. This is done by means of a rotating ring which can be rotated in the circumferential direction with at least one, in particular three control bolts, engaged in corresponding sliding guide grooves. The throttle mechanism is particularly suitable for arbitrarily adjusting the steam flow rate through an annular opening concentrically arranged with respect to the turbine shaft in front of the low pressure portion of the steam turbine. This is particularly suitable for the high extraction steam pressure of reaction turbines.

Claims (9)

A partition element (2) having at least one flow path (4) for closing the steam in the cross section (2) and arranged perpendicular to the main shaft (1) in the steam turbine component and for the flow of steam. 3) and a throttle mechanism (5) movable along the main shaft (1) for adjusting the flow rate of the steam passing through the flow path (4). The throttle mechanism (5) is a first seal surface ( 6) and a second sealing surface (7), and in the partition element (3), the channel (4) extends from the transverse section (2) along the main axis (1), and the transverse section (2 ) Having a wall (8) extending parallel to and spaced from the wall (8), the first sealing surface (6) abutting against the wall (8) in a position to close the flow path (4), by the second sealing surface at a position for closing the passage (4) (7) abuts directly bulkhead element (3) in the transverse plane (2), the flow In a position where (4) is closed, the sealing surface (6, 7) comes into airtight contact with the partition wall element (3) and at least partially opens the flow path (4). A steam turbine component, characterized in that is separated from the bulkhead element (3). Throttle mechanism (5) steam turbine components of claim 1, wherein Rukoto comprises a cylinder having a concentrically arranged annular double seat ring to the main axis (5a). Steam turbine component according to claim 1 or 2, characterized in that the cylinder with the double seat ring (5a) consists of two semi-cylindrical segments (5b, 5c). The throttle mechanism (5) is fitted with at least one guide bolt (11a, 11b) attached to the turbine housing (9), respectively, and is fitted into at least two guide grooves (10a, 10b) extending parallel to the main shaft (1). A steam turbine component according to any one of the preceding claims, comprising a turbine housing (9) characterized in that Steam turbine component according to claim 4, characterized in that the guide bolts (11a, 11b) are eccentric bolts. 6. The throttle mechanism according to claim 1, further comprising at least one sliding guide groove extending in the circumferential direction as well as in the direction of the main shaft. A steam turbine component according to claim 1. A rotating ring (13) that engages with the sliding guide groove (12) and is rotatable in the circumferential direction is provided. The rotating ring (13) rotates the diaphragm mechanism (5) in the spindle (1) by rotating in the circumferential direction. The steam turbine component according to claim 4, wherein the steam turbine component is moved in the direction of. Steam turbine component according to any one of the preceding claims, characterized in that the sealing surface (6, 7) is formed as a thin annular ring. A steam turbine comprising the steam turbine component according to any one of claims 1 to 8.

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