WO1999050533A1

WO1999050533A1 - A device for the positioning of a guide vane

Info

Publication number: WO1999050533A1
Application number: PCT/SE1999/000527
Authority: WO
Inventors: Karl-Johan NORDSTRÖM
Original assignee: Asea Brown Boveri Ab
Priority date: 1998-03-30
Filing date: 1999-03-30
Publication date: 1999-10-07
Also published as: SE9801097D0; SE9801097L; SE511687C2

Abstract

A device for positioning at least one guide vane (1) provided in a rotor machine, which guide vane is provided in a frame (3) and arranged to control a medium which flows in the rotor machine. The guide vane (1) is rotatably arranged in the frame (3) and the device comprises fixing means (9) which is arranged to fix the rotational position of the guide vane (1) relative to the frame (3) and arranged to about at least one surface (8, 12) associated with the frame and at least one surface (10) associated with the guide vane (1) for thereby fixing the guide vane (1) in a certain rotational position.

Description

A DEVICE FOR THE POSITIONING OF A GUIDE VANE

FIELD OF THE INVENTION AND PRIOR ART

The present invention concerns a device for positioning at least one guide vane provided in a rotor machine, which guide vane is provided in a frame and arranged to control a medium which flows in the rotor machine.

Such devices are known in the prior art, wherein a plurality of guide vanes are provided in one or more annular arrays of such guide vanes around the rotational axis of the rotor machine, and wherein the guide vanes are connected to a stator part included in the rotor machine. All the guide vanes in the rotor machine together form a so-called guide vane ring.

The characteristics of the guide vane ring are decisive for the amount of medium flowing through the rotor machine which will pass through the same at a defined pressure ratio for the medium before and after the guide vane ring. The amount of the medium which at the defined pressure ratio flows through the rotor machine defines thereby the so-called turbine wideness in case the rotor machine is a turbine. Consequently, the turbine wideness is determined by the characteristics of the guide vane ring. At a given number of rows or arrays of guide vanes, the turbine wideness may in particular be influenced by changing the length or the angle relative to the direction of flow of the individual guide vanes or blades .

In certain cases, e. g. when the rotor machine is a turbine connected to a PFBC-plant (Pressurized Fluidized Bed Combus- tion) , it is desirable to be able to modify the amount of the medium which passes through the rotor machine while maintaining a certain pressure ratio, i.e. without changing the pressure of the medium before and after the medium passes through the rotor machine and thereby influencing the pressure in the PFBC-process . In such turbines it is consequently desirable to change the turbine wideness by changing the form of the guide vane ring.

According to prior technology, the guide vanes of rotor machines of primarily high pressure or hot gas turbines are fixedly provided relative to the stator part to which they are attached. Often the guide vanes comprise a T-shaped or in a similar manner formed base, which is positioned in a corresponding recess in the stator part and which thereby locks the guide vane in a given angular position relative to the direction of flow of the medium. A modification of the guide vane ring thereby requires a complete dismantling of the guide vanes and a substitution of these by other guide vanes, which have a different angle between the base and the vane. This is both expensive and time consuming, because of the usually high number and relatively high price of the guide vanes and because of the amount of work needed for the dismantling and the substitution. In connection with the in- stallation of PFBC-plants, the consequence, because of this reason, may be delays of the start of the operation of the plant with up to half a year.

SUMMARY OF THE INVENTION

The purpose with the present invention is to provide a device which permits that the influence of a guide vane on a medium flowing through a rotor machine is modified, while the above mentioned disadvantages with prior technology are overcome and the construction of the device is simple, inexpensive and does not require much space . This purpose is achieved by the initially defined device, which is characterised in that the guide vane is rotatably arranged in the frame and that the device comprises fixing means arranged to fix the rotational position of the guide vane relative to the frame and arranged to abut at least one surface associated with the frame and at least one surface associated with the guide vane for thereby fixing the guide vane in a certain rotational position. Since the guide vane is rotatably arranged in the frame, it is sufficient to rotate or turn the same in the frame in order to modify the influence of the guide vane on the medium which passes by the guide vane .

By using fixing means of in principle the same construction but which permits different angles between the mentioned surfaces associated with the frame and with the guide vane, it is possible to fix the guide vane in different rotational positions just by substituting such fixing means. Substitu- tion of the guide vane itself is thereby not necessary, and the expenses associated therewith, as well for the material as for the work, may be avoided. The expenses are instead associated with the substitution of the fixing means, which expenses may be low, since the fixing means may be constructed as relatively small, inexpensive and easily substitutable locking pieces.

According to a preferred embodiment of the invention, the at least one guide vane is provided with bearing members ar- ranged in opposite ends of the guide vane, wherein at least one of the bearing members comprises the at least one abutting surface associated with the guide vane.

The fixing means does thereby not need to grip the blade of the guide vane, i.e. in the area where the guide vane is supposed to control the medium flowing in the rotor machine, and thereby is avoided that the fixing means in such a manner disturbs the flow of the medium. The provision of the bearing members in opposite ends of the guide vane guarantees the stability of the rotatable arrangement of the guide vane in the frame .

According to a further preferred embodiment of the device according to the invention, at least one of the bearing members projects through a frame portion and, relative to the guide vane on the opposite side of the frame portion, comprises the abutting surface associated with the guide vane.

It is thereby possible to position the fixing means well separated, by said frame portion, from the medium flowing on the opposite side of the frame portion. This is particularly advantageous in case the medium, by e.g. its temperature and composition, has an aggressive influence onto the material it will come into contact with, and the fixing means may hereby be spared such a contact and it may be avoided that the fixing means is worn out prematurely. The bearing member may be of a simple construction, e. g. a pin, which easily may be provided with a sealing member which prevents flowing media from passing by the same to the side of the frame portion where the fixing means is arranged.

According to a further preferred embodiment, the frame comprises at least one outer and at least one inner frame portion, arranged between support members, wherein the frame portions are formed by platforms, constricted between the support members, which are formed by stator-ring segments.

Units consisting of frame portions and guide vanes associated with these may thereby be mounted and dismounted by releasing and fixing, respectively, the frame portions in the position in which they are attached or constricted between the support members .

According to a further preferred embodiment of the device according to the invention, at least the abutting surface associated with the guide vane is formed by a bottom surface in a recess arranged in the circumference of the bearing member .

The fixing means may thereby be caused to engage the bearing member in a position defined by the recesses. This favours in particular a precise and stable positioning of the fixing means relative to the bearing member and the abutting surface associated with the guide vane requires only a small space.

According to a further embodiment of the device according to the invention, the bearing member comprises two recesses, which are arranged on opposite sides in the circumference of the bearing member and which comprise abutting surfaces.

This is, in particular, advantageous when the bearing member comprises a pin and said surfaces extend in planes which are essentially parallel with the central axis of the pin and with the rotational axis of the guide vane, under the condition that these coincide. It is thereby possible to provide the connecting means with a fork portion which grips around a portion of the pin located between said surfaces, wherein the transfer of force between the fixing means and the abut- ting surfaces associated with the guide vane may take place over a relatively large area and perpendicular to the rotational axis of the guide vane. Even a certain axial fixation may be achieved by the fork portion abutting further surfaces of the pin. According to a further embodiment of the device according to the invention, the fixing means are arranged to be displace- able into and out from their active position fixing the respective guide vane, and are, relative to the guide vane, arranged essentially on the opposite side of the frame portion which separates the respective fixing means and the guide vane .

A particular advantage is thereby achieved in connection with the substitution of the fixing means, since these may be displaced into and out from their active position without any need to dismount the guide vane from the frame portion. The modification of the turbine wideness which is demanded may consequently be done just by dismounting parts of the stator parts in question, i.e. the guide vane is permitted to remain in said frame portion.

According to a further preferred embodiment of the device according to the invention, the rotor machine is of the kind which comprises a stator part and a rotor part, wherein the stator part comprises at least one ring-shaped array of a plurality of said guide vane arranged in the frame, which array is arranged essentially coaxially with and around the rotational axis of the rotor part .

The device is in particular advantageous in this kind of rotor machine since a plurality of guide vanes exists in the same and since substitution of a plurality of guide vanes in connection with the modification of the turbine wideness may thereby be avoided.

According to a further preferred embodiment of the device according to the invention, the device is characterised in that the rotor machine comprises a plurality of guide vane arrays positioned after each other, as seen in the direction of the rotational axis of the rotor part, and that the first of these arrays, as seen in the flow direction of the medium, is provided with the guide vane.

-An advantage with this embodiment is that the turbine wide- ness is permitted to be modified with the help of the device according to the invention at that row or array of guide vanes where a certain turning or rotation of these relative to the flow direction of the medium normally has a larger effect on the turbine wideness than the corresponding turning or rotation of guide vanes in subsequent rows or arrays .

According to a particularly preferred embodiment, the rotor machine is a hot gas turbine. In such a turbine, as well as in turbines in general, it is an advantage to be able to vary the turbine wideness, and the heat and the pressure of the medium which flows through the turbine contributes to making the device according to the invention particularly advantageous, since it allows rotation and locking of turbine guide vanes even in hot turbines which demand heat shields between the channel of the medium and supporting stator parts while maintaining a compact and robust construction. Preferably, the first frame portions thereby form heat shields against the hot medium.

Since the temperature of the medium, preferably gas, entering a hot gas or high pressure turbine, is relatively high, e.g. in connection with a PFBC-plant, the device is advantageous since it allows a modification of the turbine wideness while supporting stator parts are shielded by means of heat shields which in this case consist of said frame portions, whereby the supporting stator parts are not exposed to the hot gases flowing in the turbine, and the device permits a simple, inexpensive and reliable solution to the problem with adjustable turbine guide vanes in such high pressure turbines. As an example may be mentioned that the gas entering a high pressure turbine in a PFBC-plant has a temperature of about 850° or more, which should be compared with the temperature the gas has when it reaches the subsequent low pressure turbine, where the gas temperature normally is about 600°C and where other kinds of solutions to the problem of adjusting the turbine guide vane are permitted, which solutions however do not normally permit such a robust and heat insulating solution as the device according to the invention while maintaining a low cost and a small required volume.

The invention also concerns a rotor machine, comprising a guide vane provided therein, which guide vane is provided in a frame and arranged to control a medium which flows in the rotor machine, which rotor machine is characterised in that the guide vane is rotatably arranged in the frame and that the rotor machine comprises fixing means arranged to fix the rotational position of the guide vane relative to the frame and arranged to abut at least one surface associated with the frame and at least one surface associated with the guide vane for thereby fixing the guide vane in a certain rotational position.

In a preferred embodiment of the rotor machine, the rotor machine is a gas turbine connected to a PFBC-plant, which turbine comprises a high pressure part and a low pressure part, and the guide vane is provided in a first ring of guide vanes in the high pressure part, as seen in the flow direction of the medium.

Further advantageous features will be clear from remaining dependent claims and from the following, detailed description of a preferred embodiment. SHORT DESCRIPTION OF THE DRAWINGS

The present invention will now be described in detail with reference to different embodiments which are shown in the attached drawings . In these :

Fig 1 is a longitudinal cross section of a portion of a rotor machine, only schematically shown, - Fig 2 is a view from above of the device according to the invention,

Fig 3 is a cross sectional view of the device according to the invention in the direction A in Fig 2,

Fig 4 is a perspective view of a fixing means according to the invention, and

Fig 5 is a cross sectional view of the fixing means according to the device, seen from the side.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In Fig 1 a preferred embodiment of the device according to the invention is shown, as applied at the first row of guide vanes at the inlet to a high pressure turbine . The high pressure turbine comprises guide vanes 1 connected to a stator part 6, of which guide vanes one is shown in cross- section in Fig 1. Each guide vane 1 is at two opposite ends provided with a bearing member 2 in the form of a pin, which is also clear from figures 2 and 3. With the help of the pins 2 , the guide vanes 1 are rotatably arranged in a frame 3, which is formed by outer and inner frame portions 4 and which is attached to the stator part 6 of the rotor machine via support members 5 in the form of stator ring segments .

As is indicated in Fig 1-3, the pins 2 of the guide vanes 1 extend essentially radially from a central axis (not shown) of the rotor machine, which central axis coincides with the 10

rotational axis of a rotor part 7 of the rotor machine, which rotor part is only indicated in Fig 1. The pins 2 project through the inner and outer frame portions 4, which are positioned radially inside and radially outside, respectively, of the guide vanes 1. As is clear from Fig 2, the pins 2 have an essentially circular cross-section, except at a portion where recesses are provided in them. At their bottom surface 10, the recesses form two parallel, essentially plane surfaces, which are positioned opposite each other in parallel planes and which extend essentially in the axial direction of the pins 2. The recesses are, relative to the guide vane 1, arranged to be located on opposite sides of the frame portions 4 when the pins project through the frame portions 4. The pins 2 outer circumference essentially corresponds to the inner circumference of the respective openings in the frame portions 4 through which they project .

The frame portions 4 are formed by a number of platforms, of which one is shown from above in Fig 2. The frame portions 4 are arranged such that each individual frame portion 4, i.e. platform, is arranged to hold two guide vanes 1 positioned next to each other by receiving the pins 2 of the guide vanes 1 in openings. An outer frame portion 4 is arranged radially seen exterior of two guide vanes 1 positioned next to each other and a corresponding inner frame portion 4 is arranged radially interior of these. The frame portions 4 have a rhombic shape and form together an outer and inner circumference, respectively, of a ring shaped channel, which is arranged to permit a medium to flow therethrough, preferably a gas . The guide vanes 1 are consequently arranged in this channel and by these guide vanes the medium flowing therethrough is controlled. This medium normally has a high temperature and the frame portions 4 are arranged to act as heat shields between the channel for the medium and supporting stator parts (not shown) connected with the frame 11

portions. The frame portions 4 are clamped between the support members 5, which are formed by stator rings or ring segments and which fix the position of the frame portions 4. The gaps between the guide vanes 1 and the frame portions 4 are very small in order to avoid leakage through these gaps .

Furthermore, each frame portion 4 comprises a surface 8 associated therewith, which surface a fixing means 9 is arranged to abut such that it fixes the guide vane 1 in a certain angular or rotational position. The fixation of the fixing means 9 is done by the fact that the fixing means simultaneously abuts two surfaces 10 associated with the guide vane 1, which surfaces here correspond to the plane surfaces which exist in the bottom of the recesses arranged in the pins 2, which recesses have been described above. The abutting surface 8 associated with the frame 3, i.e. the frame portion 4, is formed by a wall of a tangentially directed projection 11 of the frame portions 4. Also the support members 5 comprise a surface 12, which the fixing means 9 is arranged to abut. The abutting surfaces 8 and 12 connected with the frame portion 4 and the support members 5, respectively, are plane and arranged to between them fix the fixing means 9 in a certain position. A corresponding surface of the frame portions 4 also abuts the surface 12. The portion of the abutting surface 12 which is associated with the support members 5 and which the fixing means abuts is to be considered as a abutting surface associated with the frame 3.

The fixing means 9 have the shape of a yoke or fork, which has surfaces 13 , 14 arranged to abut the surface or surfaces 10 provided on the pin 2 of the guide vane 1. These abutting surfaces 13 , 14 of the fixing means 9 are arranged on the inside of the legs 15, 16 forming part of the fixing means, which legs are displaceably arranged to be positioned in a position where they engage the recesses which are formed in 12

the pins 2 and which define the surfaces 10. The fixing means 9 also has surfaces 17, 18 arranged to abut the corresponding surface 8 of the frame portion 4. These surfaces 17, 18 are arranged at the outer ends of the legs 15, 16. Furthermore, the fixing means 11 comprises a further abutting surface 19, which is arranged to abut the corresponding surface 12 connected with the support members 5. All the mentioned abutting surfaces 10, 13, 14, 17, 18, 19 are angled relative to the rotational plane of the bearing member 2 and the guide vane 1. In the shown preferred example, said angle is perpendicular.

The fixing means 9 are further provided with an elevation 20, the main function of which is to facilitate the gripping of the fixing means 9 in connection with the substitution of these. By substituting the fixing means, which has a certain angle between the abutting surfaces 13 , 14 and the abutting surface 19 and the surfaces 17, 18, respectively, with fixing means with a different angle therebetween, it is possible to change the angular position of the guide vanes 1 arranged in the frame 3 and to thereby achieve a modification of the guide vane ring of which the guide vanes 1 form a part .

The row or the array of guide vanes 1 provided with the device according to the invention is, according to the preferred embodiment, the first of a plurality of rows of guide vanes . The rotor machine is preferably a turbine in which this first row of guide vanes 1 forms part of the guide vane ring and which allows a hot medium in the form of a gas to flow therethrough. In a particularly preferred embodiment, the turbine is arranged in connection to a PFBC- plant and forms a high pressure turbine belonging thereto, in which turbine the entering gases have a temperature of about 850°C or more and in which it is desirable to isolate supporting stator parts from the hot gas flowing by the 13

guide vanes 1. In such a plant , changed parameters of operation as well as a changed fuel quality in the coal- fired PFBC-plant may cause a need for a modified turbine wideness, wherein the device according to the invention may be used for this purpose .

Of cause, a number of modifications and alternative embodiments of the device according to the present invention are possible. The invention should therefore only be seen as being limited by the features defined in the following claims and by what additionally has become clear from this description.

For example, it would be possible to arrange the device according to the invention in connection with other rotor machines than pure high pressure or hot gas turbines, such as, for example, a steam turbine or a compressor. It is also possible to position the device according to the invention at the second, third or any further subsequent row or ring of guide vanes when a plurality of such rows or rings exists in the longitudinal direction of the rotor machine.

It is also possible to arrange the frame portions 4 in a different manner than such that each frame portion 4 holds two guide vanes 1 located next to each other. For example for receiving the pins of only one or three or possibly four guide vanes .

It is also possible to only arrange the fixing means 9 according to the invention at one end of the guide vanes 1.

The fixation at both ends gives, however, higher stability and is therefore preferred.

Claims

14Claims

1. A device for positioning at least one guide vane (1) provided in a rotor machine, which guide vane is provided in a frame (3) and arranged to control a medium which flows in the rotor machine, characterised in that the guide vane (1) is rotatably arranged in the frame (3) and that the device comprises fixing means (9) arranged to fix the rotational position of the guide vane (1) relative to the frame (3) and arranged to abut at least one surface (8, 12) associated with the frame (3) and at least one surface (10) associated with the guide vane (1) for thereby fixing the guide vane (1) in a certain rotational position.

2. A device according to claim 1, characterised in that the guide vane (1) is provided with bearing members (2) arranged in opposite ends of the guide vane (1) .

3. A device according to claim 2, characterised in that at least one of the bearing members (2) comprises the abutting surface (10) associated with the guide vane (1) .

. A device according to claim 3 , characterised in that at least one of the bearing members (2) projects through a frame portion (4) and, relative to the guide vane (1) on the opposite side of the frame portion (4) , comprises the abutting surface (10) associated with the guide vane (1) .

5. A device according to claim 4 , characterised in that the frame (3) comprises at least one outer and at least one inner frame portion (4) , arranged between support members (5) .

6. A device according to claim 5 , characterised in that the frame portions (4) are formed by platforms, constricted 15

between the support members (5) , which are formed by stator ring segments .

7. A device according to anyone of the claims 5 or 6 , characterised in that each frame portion (4) is arranged to support two guide vanes (1) positioned next to each other.

8. A device according to anyone of the claims 5-7, characterised in that the frame portions (4) are arranged to func- tion as heat shields between the medium flowing in the rotor machine and supporting stator parts.

9. A device according to anyone of the claims 2-8, characterised in that the abutting surface (10) associated with the guide vane (1) is formed by a bottom surface in a recess arranged in the circumference of the bearing member (2) .

10. A device according to anyone of the claims 2-9, charac- terised in that it comprises two recesses, which are arranged on opposite sides in the circumference of the bearing member (2) , and which comprises abutting surfaces (10) associated with the guide vane.

11. A device according to anyone of the preceding claims, characterised in that the fixing means (9) are arranged to be displaceable into and out from their active position fixing the respective guide vane (1) .

12. A device according to anyone of the preceding claims, characterised in that the fixing means (9) comprises at least a first support surface (13, 14), arranged to abut the abutting surface (10) associated with the guide vane (1) and at least one second support surface (17, 18, 19) arranged to abut the abutting surface (8, 12) associated with the frame 16

(3), and that an angle is formed between the first (13, 14) and second (17, 18, 19) support surfaces.

13. A device according to claim 12, characterised in that the fixing means (9) comprises a fork-shaped locking part provided with two legs (15, 16) on the insides of which the first support surfaces (13, 14) are provided and wherein the second support surfaces (17, 18, 19) are provided at the ends of the legs (15, 16) and, relative to the legs, at the opposite end of the fork, respectively.

14. A device according to anyone of the preceding claims, characterised in that the rotor machine is of the kind which comprises a stator part (6) and a rotor part (7) and that the stator part (6) comprises at least one ring-shaped array of a plurality of said guide vane (1) arranged in the frame (3) , which array is arranged essentially coaxially with and around the rotational axis of the rotor part (7) .

15. A device according to claim 14, characterised in that the rotor machine comprises a plurality of guide vane arrays positioned after each other, as seen in the direction of the rotational axis of the rotor part (7) , and that the first of these arrays, as seen in the flow direction of the medium, is provided with the guide vane (1) .

16. A device according to anyone of the preceding claims, characterised in that rotor machine is a hot gas turbine .

17. A device according to anyone of the preceding claims, characterised in that the rotor machine is a high pressure turbine connected to a PFBC-plant.

18. A rotor machine, comprising a guide vane (1) provided therein, which guide vane is provided in a frame (3) and arranged to control a medium which flows in the rotor machine, 17

characterised in that the guide vane (1) is rotatably arranged in the frame (3) and that the rotor machine comprises fixing means (9) arranged to fix the rotational position of the guide vane (1) relative to the frame (3) and arranged to abut at least one surface (8, 12) associated with the frame (3) and at least one surface (10) associated with the guide vane (1) for thereby fixing the guide vane (1) in a certain rotational position.

19. A rotor machine according to claim 18, characterised in that it is a gas turbine connected to a PFBC-plant, which turbine comprises a high pressure part and a low pressure part, and the guide vane (1) is provided in a first ring of guide vanes (1) in the high pressure part, as seen in the flow direction of the medium.