WO2002027169A1

WO2002027169A1 - A connecting device

Info

Publication number: WO2002027169A1
Application number: PCT/SE2001/002088
Authority: WO
Inventors: Johan Mattson; Johnny Rehn
Original assignee: Turbec Ab
Priority date: 2000-09-29
Filing date: 2001-09-28
Publication date: 2002-04-04
Also published as: SE0003548D0; AU2001292477A1; SE520576C2; SE0003548L

Abstract

A heat engine unit (20) has an connecting device (10), the connecting device being in communication with a heat engine stage (5) at a first end (10a), and in communication with subsequent stages of the heat engine unit, e g a heat exchanger (6) or a recuperator, at a second end (10b). The connecting device (10) is allowed to expand when exposed to heat by being lodged to slide axially at said first end (10a). Furthermore, the connecting device is supported at said second end (10b) by way of a contact surface (50) formed between said second end and supporting means (30) to allow tilting of the connecting device.

Description

A CONNECTING DEVICE

Field of the Invention The present invention relates to a connecting device for a heat engine unit, the connecting device being in communication with a heat engine stage at a first end, and in communication with subsequent stages of the heat engine unit, e g a heat exchanger or a recuperator, at a second end. The connecting device also comprises supporting means and sealings.

Prior Art

A heat engine, for example a gas turbine can be of an axial or radial type with one or more compressor and/or turbine stages, depending on the power and heat requirement, and available space. Different power requirements and heat outputs lead to different sizes and types of gas turbines. One feature often common for the different types of gas turbines is that an heat exchanger is provided after the gas turbine stages in order to increase the efficiency of the gas turbine by raising the temperature of the compressor air before it enters the combustion chamber by way of using the excess heat in the exhaust gas . The heat exchanger, e g in the form of a recuperator, may have a very large area in relation to the discharge area of the gas turbine stages for receiving the exhaust gas . This area ratio between the discharge area of the gas turbine stages and the front area of the recuperator has to be bridged over in some way so that the transition for the exhaust gas during its delivery between these areas is sufficiently smooth and the exhaust gas is dispersed as evenly as possible over the front area of the recuperator. One way of overbridging the area ratio between the gas turbine stages and the recuperator after the gas turbine stages is to use a diffusor or conduit, which is located between the gas turbine stages and the subsequent stages, e g the heat exchanger or recuperator stages, having an increasing area from its end adjacent the gas turbin stages towards the recuperator stages. Moreover, by using a diffusor the dynamical component of the exhaust gas pressure is maintained and utilized as long as possible. One way of making a diffusor or a conduit is to wrap a metal plate into a frustoconical shape and weld the joint together along the cone . This solution of a diffusor or conduit has some disadvantages, first, it has to be attached, in most cases by welding for ensuring a sufficient sealing, to other parts so that an unit is formed that may be assembled in the gas turbine unit. This unit, which comprises several parts that are welded together, may also have to be welded against supporting parts in the gas turbine unit for a sufficiently secure attachment and sealing. This makes the unit more complex with more welds and parts that can obtain flaws during the welding. This creates a higher risk of welds cracking, which may cause gas leakage, when the unit is thermally strained, i e by heat expansion, during operation of the gas turbine unit. Moreover, the installation and maintenance of the diffusor unit become more difficult and time-consuming due to higher demands on the welding and several working moments when assembling the unit in the gas turbine unit .

Summary of the Invention

The main objects of the present invention are to simplify the construction and assembly of connecting devices in gas turbine units, reduce the number of working moments during the assembly, and enhance the durability for the connecting devices against thermal strain and pressure load. These objects are achieved for heat engine units by providing them with a connecting device according to the invention. The connecting device is in communication with a heat engine stage at a first end, and in communication with subsequent stages of the heat engine unit, e g a heat exchanger or a recuperator, at a second end. The connecting device is allowed to expand when exposed to heat by being lodged to slide axially at said first end, and is supported by way of a contact surface formed between a part of the connecting device and supporting means, thereby allowing tilting of the connecting device.

By providing a heat engine unit with a connecting device according to the invention, a simpler construction with, fewer parts due to an integrally manufactured connecting device reduces associated working moments during manufacturing processes, e g welding or bracing. Furthermore, the possibility of axial expansion for the connecting device when exposed to heat reduces the thermal strain in the connecting device and enhances its durability against thermal strain and pressure load. Moreover, the contact surface formed between the connecting device and the supporting means permits tilting of the connecting device, whereby a tight sealing between these parts is secured. Also, the installation and maintenance of the connecting device are simplified due to less or ho welding and no cutting when changing connecting devices.

Brief Description of the Drawings

The present invention will now be described in further detail, reference being made to the accompanying drawings, in which:

FIG 1 is a longitudinal side view in section showing a preferred embodiment of a connecting device according to the invention mounted in a heat engine unit, FIG 2 is a longitudinal side view in section showing a preferred embodiment of the connecting device in FIG 1.

Detailed Description of the Invention FIG 1 shows a connecting device 10 according to the invention mounted in a heat engine, in this case a gas turbine unit 20 but could also be used in a internal- combustion engine. The gas turbine unit comprises an inlet 1, a housing 2, a combustion chamber 3 (only partly shown) , a connecting flange 4, a gas turbine stage 5, a heat exchanger 6 (only partly shown) in the form of a recuperator, and a supporting flange 30. The connecting device 10 may function as a diffusor or only as a conduit for leading gas from one end to another. FIG 2 illustrates a view in section of the connecting device 10 according to the invention in a preferred embodiment. The connecting device is shown assembled between the connecting flange 4 of the gas turbine stage 5 (shown in FIG 1) and the supporting flange 30 located before the heat exchanger 6. The connecting device 10 is manufactured in one piece, preferably by casting but could be made by any other suitable method, with a frustoconical outer shape. The connecting device preferably has a cylindrical cross-section but may have any other shape of the cross-section, which is obvious to a person skilled in the art. These different shapes depend on, e g available space in the gas turbine unit 20 or the design of the area of the heat exchanger 6 receiving a gas, i e the recuperator area receiving the gas may have a non- symmetrical shape, whereby the cross-section of the connecting device must have a cross-section that varies along its length, e g from a cylindrical shape at its first end 10a into an oval shape at its second end 10b. Moreover, the cross-section of the connecting device 10 could have a quadratic or rectangular shape at one end or both, if required according to the demands described above . Furthermore, the connecting device may have a cylindrical inner cross-section but a square outer cross-section or an outer cross-section with more than 4 sides, e g at least 5 sides forming a pentagon-shaped cross-section. If the connecting device would function only as a conduit it could have a conical inner through hole with an increasing area in one direction and an outer shape with an increasing area in the opposite direction. The connecting device has two ends, a first end 10a and a second end 10b. Here, the diameter of the connecting device 10 increases from its first end 10a towards its second end 10b. Each end is provided with at least one sealing in the form of a laminar ring sealing 40a, 40b for sealing the gas in the connecting device from the surrounding. The connecting device' also has an axially extending inner through hole with a conical shape essentially corresponding to the conical outer surface of the connecting device . The centre of the inner through hole coincides with the centre of the connecting device 10.

Alternatively, the centre of the inner through hole could be displaced in relation to the centre of the outer shape, i e the centre axis do not have to coincide with each other, the centre axis may even diverge or converge. The centre of the opening at each end 10a and 10b of the connecting device may also be displaced in relation to each other, whereby the connecting device could have a curved or essentially S-shaped form. The connecting device has its first end 10a in engagement with an adjacent end 4a of the connecting flange 4, and its second end 10b in^' engagement with and supported by the supporting flange 30. The connecting flange 4 is rotary symmetrical with an essentially L-shaped cross-section provided with one end or leg pointing essentially in the radial direction, and one end or leg 4a pointing in the axial direction towards the connecting device 10. The supporting flange 30 has two rotary symmetrical main parts, a first protruding part 110 with an essentially cylindrical shape pointing towards the connecting device 10, and a second part with a conical shape extending in the opposite direction towards the heat exchanger 6. The connecting flange may have a non- symmtrical shape, e g a shape with more than 4 sides, e g a pentagon-shape, or a pear-shape or any other shape fulfilling the demands. The connecting device 10 is supported by the supporting flange 30 by way of a spherical outer surface 60 provided at its second end 10b being in contact with a conical inner surface 70 of the supporting flange 30 during operation of the gas turbine unit 20. The contact surface or support surface formed between the spherical outer surface and the conical inner surface has the shape of a tangential circumferential contact surface 50, which allows tilting of the connecting device. The spherical outer surface 60 may be located at any other location on the connecting device 10 instead of the second end 10b, the most important is that the sealing and tilting function for the connecting device are achieved. The spherical outer surface 60 may be formed on a part of the connecting device which is located anywhere between its ends 10a and 10b. The spherical outer surface 60 on the connecting device and the conical inner surface 70 on the supporting flange 30 may also change places, i e the conical surface may be placed on the connecting device and the spherical surface on the supporting flange. Both of these surfaces 60 and 70 may also be spherical.

FIG 2 also shows an enlargement of the spherical outer surface 60 and the conical inner surface 70 for clarity reasons . The radius of the spherical outer surface is designated with an arrow R. The radius R is defined during the dimensioning of it so that it fulfills the condition that the contact point between the spherical outer surface and the conical inner surface always is in a position on the conical inner surface which gives the largest area as possible in which the connecting device can move in both directions when tilting, this does not have to be the case during operation of the gas turbine unit 20. The relation between the lower and upper positions in the radial direction of the contact surface may vary.

The radius R may be in the interval of about 120-150 mm but the size of the radius R depends on several factors, e g the dimensions of the associated parts and especially the conical angle of the conical inner surface. In this case, the preferred radius R for the spherical outer surface 60 is about 130-140 mm but most preferred about 135 mm when the conical angle at the conical inner surface 70 is 45°. Other conical angles may be conceived by a man skilled in the art, for example a conical angle of 30° and other dimensions of the connecting device would give another radius, i e these parameters depends on each other. The tilting function for the connecting device is required as the connecting device 10 may, in some cases, have an askew position, due to an uneven thermal expansion and/or a non-uniform distribution of the surrounding pressure around its outer surface, which has to be compensated for by tilting the connecting device, also tolerance flaws or manufacturing flaws or flaws during the assembly of the connecting device may have to be compensated for by tilting it. Still, a sufficient sealing has to be maintained between the gas inside the connecting device 10 and the surrounding both in the possible askew position for the connecting device and during its thermal expansion. This is achieved by the laminar ring sealings 40a and 40b provided at the ends 10a and 10b, respectively, of the connecting device 10. The laminar ring sealings 40a, 40b are slidable radially in relation to each other but are essentially fixed in relation to the connecting device, thereby following the motion of the connecting device, so that their contact with associated sealing surfaces is kept at both sides of the connecting device at all times even though it tilts.

The sealing function may also be achieved by designing each end 10a and 10b of the connecting device 10 in a way corresponding to the design or form of the associated surrounding sealing surfaces, i e the connecting flange 4 and the supporting flange 30, whereby the forms of these parts 10a, 10b, 4, and 30 together create a tight sealing, e g the ends 10a and 10b could" be patterned with patterns fitting into patterns in the surrounding surfaces. These patterns could for example be ribs, peaks, or bulges fitting into dents or grooves with tolerances creating a sufficiently tight sealing. Moreover, the sealing function may also be achieved with piston rings, o-rings withstanding high temperatures, or C-sealings.

The contact between the spherical outer surface 60 and the conical inner surface 70 is achieved and kept due to a high pressure from the surrounding, i e due to the higher pressure of recuperated compressor air delivered through the inlet 1 and surrounding the connecting device 10, forcing the connecting device and its second end 10b against the supporting flange 30 by way of force- or pressure components in the axial direction towards the supporting flange. These components are created by the high pressure distributed around the conical outer surface of the connecting device 10 during operation of the gas turbine unit 20.

The connecting device 10 is provided with grooves at both ends 10a, 10b for containing and fixing the laminar ring sealings 40a, 40b in relation to the connecting device. The first end 10a of the connecting device has one circumferential groove 80 located at its inside so that one ) w Ni »— - o is.

works as an axial expansion space 150 when the connecting device expands axially due to thermal strain, i e heat expansion, when the gas turbine unit is operated. The main thermal axial expansion of the connecting device 10 occurs in the direction towards the gas turbine stage 5, i e in the expansion space 150 always having a length that extends the maximum distance that may be covered by the first end 10a of the connecting device 10 during its axial expansion, i e the first end 10a of the connecting device always overlaps the connecting flange but do not reach the shoulder 140 when expanding, whereby any build-up of strain or forces in the axial direction or pressure load in the radial direction are eliminated. A sufficient sealing is also maintained in that each laminar ring sealing 40a, which is located in the groove 80 at the first end 10a of the connecting device 10, keeps their contact with associated sealing surfaces, i e the outer surface 130 of the connecting device 10 and the inner surface of the groove 80 at all times due to sufficiently long portions of the first end 10a and the connecting flange 4 overlapping each other, thereby always covering each laminar ring sealing 40a.

The protruding part 110 of the supporting flange 30 extends a distance over the second end 10b of the connecting device 10, this distance is sufficiently long in that the inner surface 100 of the supporting flange 30 always covers each laminar ring sealing 40b by extending past each laminar ring at all times. This sufficient length of the inner surface 100 ensures that a sufficient sealing is maintained in that at least one laminar ring sealing 40b, which is located in the groove 90 at the second end 10b of the connecting device 10, always keeps its contact with the inner surface 100 of the supporting flange 30 and the inner surface of the groove 90 independently of how much the connecting device 10 tilts. The connecting device

Claims

1. A connecting device (10) for a heat engine unit (20) , the connecting device being in communication with a heat engine stage (5) at a first end (10a) , and in communication with subsequent stages of the heat engine unit, e g a heat exchanger (6) or a recuperator, at a second end (10b) , c h a r a c t e r i z e d in that the connecting device (10) is allowed to expand when exposed to heat by being lodged to slide axially at said first end (10a) , and in that the connecting device is supported by way of a contact surface (50) formed between a part of the connecting device and supporting means (30) to allow tilting of the connecting device.

2. A connecting device (10) according to claim 1, wherein said contact surface (50) is formed at an outer portion of the connecting device located between said first end (10a) and said second end (10b) of the connecting device .

3. A connecting device (10) according to claim 1, wherein said contact surface (50) is formed by way of a spherical surface (60) at the second end (10b) of the connecting device being in contact with a conical surface (70) of said supporting means (30) .

4. A connecting device (10) according to claim 1, wherein said contact surface (50) is formed by way of a spherical surface at the supporting means (30) being in contact with a conical surface at the second end (10b) of connecting device.

5. A connecting device (10) according to claim 1, wherein said contact surface (50) is formed by way of a spherical surface (60) at the second end (10b) of the connecting device being in contact with a spherical surface at the supporting means (30) .

6. A connecting device (10) according to claim 2, wherein said contact surface (50) is formed by way of a spherical surface (60) on the outer portion of the connecting device being in contact with a conical surface (70) at the supporting means (30) .

7. A connecting device (10) according to claim 2, wherein said contact surface (50) is formed by way of a spherical surface (60) on the outer portion of the connecting device being in contact with a spherical surface at the supporting means (30) .

8. A connecting device (10) according to claim 2, wherein said contact surface (50) is formed by way of a conical surface on the outer portion of the connecting device being in contact with a spherical surface at the supporting means (30) .

9. A connecting device (10) according to any of the previous claims, wherein the connecting device is made in at least one piece.

10. A connecting device (10) according to any of the previous claims, wherein the connecting device has an outer shape differing from the shape of its interior.

11. A connecting device (10) according to any of the previous claims, wherein the centre of the outer shape of the connecting device is displaced in relation to the centre of its interior. > ,_ o er, O o en

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16. A connecting device (10) according to any of the previous claims, wherein the connecting device is provided with at least one groove (80) formed at said first end (10a) and at least one groove (90) formed at said second end (10b) for containing and holding sealings (40a, 40b) in relation to the connecting means and the supporting means, respectively.

17. A connecting device (10) according to any of the previous claims, wherein the connecting device is in engagement with connecting means (4) of the heat engine stage (5) at its first end (10a) .

18. A connecting device (10) according to claim 17, wherein the connecting means (4) of the heat engine stage (5) is provided with at least one groove (80) formed at its end (4a) , which is in engagement with the connecting device, and the supporting means (30) is provided with at least one groove (90) formed at its end (110) , which is in engagement with the connecting device, for containing and holding sealings (40a, 40b) in relation to the connecting means and the supporting means, respectively.

19. A connecting device (10) according to- any of the claims 16-18, wherein said sealings (40a, 0b) are laminar rings .

20. A connecting device (10) according to claim 3 or 4 or 5 or 6 or 7 or 8, wherein said spherical surface (60) has an radius of about 130-140 mm and most preferred about 135 mm.

21. A connecting device (10) according to any of the claims 16-20, wherein the connecting device is provided with one sealing (40a) at its first end (10a) and two sealings (40b) at its second end (10b) .

22. A connecting device (10) according to any of the previous claims, wherein said connecting device is made of a heat resistant material , e g metal or ceramics .

23. A connecting device (10) according to any of the previous claims, wherein said connecting device is a diffusor.