WO2003087558A1

WO2003087558A1 - A shield device

Info

Publication number: WO2003087558A1
Application number: PCT/SE2003/000489
Authority: WO
Inventors: Johnny Rehn
Original assignee: Turbec Ab
Priority date: 2002-04-09
Filing date: 2003-03-25
Publication date: 2003-10-23
Also published as: SE522264C2; AU2003216016A1; SE0201063D0; SE0201063L

Abstract

A gas turbine unit (10) has a shield device (20) for connecting a turbine housing (30) with a compressor housing (40). The shield device supports and centers the turbine housing and forms a heat and/or pressure barrier between the turbine housing and the compressor housing. The shield device (20) is an essentially rotary symmetrical hollow element attached with a first end (20’) to the turbine housing (30) by supports (30’) being symmetrically distributed around a front surface on the turbine housing. The supports (30’) protrude past the first end (20’) of the shield device (20) in the axial direction of the shield device and are in the vicinity of the inner and/or the outer surface of the shield device.

Description

A SHIELD DEVICE

Field of the Invention

The present invention relates to a gas turbine unit comprising a shield device for connecting a turbine housing with a compressor housing. The shield device functions both as a support and centring for a turbine stator and a heat and/or pressure barrier between the turbine housing and the compressor housing.

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 at least one support and/or shield device is required for connecting a turbine stator with a compressor or turbine housing. This support and/or shield device often also sfunctions both as a pressure barrier between the airside and the gas side and a heat barrier between the turbine and compressor side.

The support and/or shield device is arranged between the "cold" and "hot" sides of the gas turbine unit. This heat- and pressure insulating function is required for maintaining the difference in temperature between the enclosed areas of the compressor housing and the turbine housing, respectively, and for maintaining the pressure difference between the air/gas surrounding the turbine housing and the enclosed area of the turbine housing.

More specifically, the heat-insulating function for the support and/or shield device is required for reducing heat flow from the turbine to the compressor side. Good insulating properties give less heat losses, thereby improving engine performance and reducing the need of expensive high temperature alloys in the compressor section. Moreover, the pressure barrier function of the support and/or shield device is required for sealing between the airside and the turbine stage flow path side . The air surrounding the device on the radial outside, i.e. the airside, is pressurised in the compressor and preheated in the recuperator, i.e. if the gas turbine is equipped with a recuperator. This air has to be prevented, as far as possible, from entering the enclosed area of the turbine stage. Uncontrolled air leakage into the turbine stage flow path has high impact both on engine performance and exhaust emissions .

This heat and/or pressure insulating support and/or shield device has axially, centre and rotationally locking functions and can have sealing functions. These functions are required for keeping all of the associated/adjoining parts in the compressor and turbine area and the housings including the rotor system in their right positions in relation to each other and sufficiently sealed from each other at the same time.

One way of achieving the centre function for the support and/or shield device is to use diameter guidance, i.e. manufacturing the support and/or shield device and adjoining parts with guiding diameters having narrow tolerances and in some cases initial loose fit. This initial loose fit, i.e. in a cold engine, may be required for keeping down the contact pressure between associated parts when the gas turbine unit is operating and all associated parts have fully expanded due to thermal load. The centre and locking function between the support and/or shield device and the associated parts, in prior art, enclosing the turbine stage are achieved by using a number of cylindrical pins extending in the radial direction of the gas turbine unit. Here, the cylindrical pins are press fitted and have a long guiding length in the support/shield device but a loose fit and a relatively short guiding length in the associated part, in this case a stator part, enclosing the turbine stage. This allows the stator part of the turbine stage to expand thermally, especially in the radial direction, in relation to the support and/or shield device while maintaining its centre in the right position without creating large radial forces and/or deformations.

The axial and rotational lock between the support and/or shield device and the associated parts of the compressor and turbine stage are achieved by using a screw joint between the support and/or shield device and the compressor stage. This screw joint co-operates with the cylindrical pin joint between the support and/or shield device and the stator part of the turbine stage for maintaining the axial and rotational lock.

The heat barrier function of the support and/or shield device is achieved by designing it with a thin web/rib, i.e. a small thickness or cross-section, so that less heat is transferred during operation of the gas turbine unit. Furthermore, the cylindrical pins between the support and/or shield device and the stator part have a relatively small contact, whereby less heat is transferred from the "hot" part, i.e. the stator part, through a "cold" part, i.e. the support and/or shield device, to the compressor housing.

Such an earlier support and/or shield device has some disadvantages, first, it has to be attached, against the compressor side by a complicated screw joint, whereby a sufficient sealing is difficult to achieve in the gas turbine unit. Furthermore, the cylindrical pins and the diameter guidance, which are used for attaching the support and/or shield device to the turbine side and keeping the centre of the stator part in position, require a large effort in manufacturing due to their narrow tolerances, thereby increasing the time and costs during manufacturing. This support and/or shield device also comprises many parts, which complicate the mounting against supporting parts in the gas turbine unit and increase the effort and costs for this measurement. Moreover, the maintenance of the support and/or shield device become more difficult and time-consuming due to its complicated design and many parts requiring unnecessary working moments when maintaining the device in the gas turbine unit .

Summary of the Invention

The main objects of the present invention are to simplify the construction and assembly of support and/or shield devices, i.e. conduits and/or tubes between the "cold" and "hot" sides, having both a support and an insulating function in heat engines; facilitate the sealing between the support and/or shield devices and associated parts of the heat engines; and enhance the insulation of heat and/or pressure between associated parts in heat engines so that the differences in heat and/or pressure between the "cold" and "hot" sides are kept during operation of the heat engines.

The support and/or shield device will be called only shield device in the description from now on for simplicity reasons .

These objects are achieved for a heat engine, preferably, a gas turbine unit by providing them with a shield device according to the invention. The gas turbine unit comprises a shield device for connecting a turbine housing, e.g. a turbine stator, with a compressor housing, the shield device functions both as a support and centring for a turbine stator and a heat and/or pressure barrier between the turbine housing and the compressor housing. The shield device is an essentially rotary symmetrical hollow element attached with a first end to the turbine housing by a support device being symmetrically distributed around the periphery of a front surface on the turbine housing. The support device protrudes past the first end of the shield device in the axial direction of the shield device and is in contact with the inner surface and/or the outer surface of the shield device .

Moreover, the shield device is attached with its second end to the compressor housing by another support device also being symmetrically distributed around the periphery of a front surface on the compressor housing. This support device protrudes past the second end of the shield device in the axial direction of the shield device and is in contact with the inner surface and/or outer surface of the shield device. By providing a gas turbine unit with the shield device according to the invention the following advantages are obtained. The manufacturing is simplified, thereby reducing associated costs. Moreover, the loads transferred through the shield device are reduced, whereby less deformation of adjacent parts and better control of the engine performance are achieved. Furthermore, the heat losses are reduced, whereby the engine performance is enhanced and the need of expensive high temperature alloys in the compressor section is eliminated. In addition, by preventing uncontrolled air leakage into the turbine stage flow path according to the invention, the exhaust emissions are reduced. The centring of the turbine housing, i.e. the turbine stator, in relation to the turbine wheel is improved giving a more robust construction/design. The improved centring can even be used for reducing the clearance, i.e. permit more narrow tolerances, which will improve the engine performance . 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 plan side view in section of a preferred embodiment of a shield device according to the invention mounted in a gas turbine unit,

FIG 2 is a transparent perspective view in section of the shield device in FIG 1, FIG 3 is a plan side view in section of the shield device in FIG 1,

FIG 4 is a plan view in section of the support for the shield device seen in the axial direction of the gas turbine unit, FIG 5 is a plan view of the support at one end of the shield device in FIG 3 seen in the axial direction of the gas turbine unit, and

FIG 6 is a plan view in section of the support at the other end of the shield device in FIG 3 seen in the axial direction of the gas turbine unit.

Detailed Description of the Invention

FIG 1 illustrates a part of a heat engine, in this embodiment, a gas turbine unit 10 with an external combustion chamber (not shown) but could also be used in an internal-combustion engine, e.g. as an intake and/or exhaust manifold or any other conduit. A shield device 20 is fitted in a housing of the gas turbine unit (not wholly shown) between the "hot" side, i.e. a gas turbine enclosure 30, and the "cold" side, i.e. a compressor enclosure 40, of the gas turbine unit. The "hot" and "cold" sides of the gas turbine unit 10 comprises of course more parts, e.g. conduits for leading air and gas, as is envisaged by a skilled person, but these are excluded for clarity reasons. The shield device 20 is shown assembled, with one of its ends 20' against a "hot" part in the form of a stator part 30 forming an enclosure/housing for the turbine stage 11 to the right in FIG 1. Here, the turbine stage is a radial turbine but could be any other type of turbine, e.g. an axial turbine. The gas turbine unit 10 also comprises a generator, an air inlet, and other parts required for starting and operating the gas turbine unit 10, as is readily understood by skilled person, these parts are excluded and not explained in the description for clarity reasons .

FIG 1 shows the shield device 20 according to the invention. The shield device is mounted between two main parts of the gas turbine unit 10, a first part, i.e. the stator part 30, to the right in FIG 1, and a second part, i.e. the compressor enclosure 40, comprising a compressor stage 12, to the left in FIG 1. Each of the enclosures for the gas turbine stage 11 and the compressor stage 12 comprises other parts, which will not be explained further, as is readily understood by a skilled person. The thickness of the shield device 20 should be between 1 to 20% of its diameter, but preferably between 2 and 15%.

In FIG 1, the shield device 20 is attached with one of its ends, the right end 20', to the turbine enclosure or housing 30, i.e. the stator part, enclosing the gas turbine stage 11. Only an upper part of the end 20' of the shield device is shown attached to the stator part for clarity reasons. The other end, the left end 20" of the shield device is partly shown attached to the compressor housing 40 enclosing the compressor stage 12 at a lower end. Here, the shield device is attached against associated parts 30 and 40 by rivets 50, of which only two are shown. FIG 2 illustrates the shield device 20 in a transparent state . Only parts of the front surfaces of the stator part 30 and the compressor enclosure or housing 40 against which the shield device is attached by the rivets 50 are shown.

FIG 3 is a view similar to FIG 1 but with all parts excluded, except for the shield device 20, the same parts of the front surfaces of the turbine stage enclosure 30 and the compressor stage enclosure 40 as shown in FIG 2, and the rivets 50. In the upper part of FIG 3, the shield device is placed with its right end 20' over a support device in the form of supporting points/nodes 30' of the turbine stage enclosure seen in the radial direction of the gas turbine unit 10. This means that the supporting points 30' of the turbine enclosure 30 support the shield device 20 from the inside of its right end 20' . The left end 20" of the shield device 20 is placed inside supporting points or nodes 40' of the compressor enclosure 40 seen in the radial direction of the gas turbine unit 10. This means that the supporting points 40' of the compressor enclosure 40 support the left end 20" of the shield device 20 from the outside. The support may of course be achieved by a double support at only one end, i.e. the right end 20' or the left end 20" of the shield device, or at both ends 20' and 20". This means that the associated end could be supported from both the inside and the outside at the same time, whereby the supporting points 30' and/or 40' could be placed around the periphery/circumference of both the inside and the outside surface of the associated end to be supported.

In FIG 4, the shield device 20 and all the supporting points/nodes 30' and 40' are shown with dotted lines and a part of the front surface of the compressor enclosure 40 is shown with solid lines. FIG 4 shows all the parts associated with the invention during normal operation of the gas turbine unit 10, as seen in a view from the direction shown with arrows and line A-A to the right in FIG 3. The turbine enclosure 30 is excluded for clarity reasons. Here, only the supporting points 30' of the turbine enclosure 30 are displaced somewhat in the radial direction of the gas turbine unit 10, i.e. the end 20' of the shield device 20 is shown deformed. The end 20' of the shield device has a somewhat irregular/deformed circular cross-section. This deformation is shown exaggerated for clarity reasons and is created when a thermal expansion in the radial direction for the "hot" part, i.e. the turbine enclosure 30, deforms the right end 20' of the shield device 20.

The "hot" stator part 30 expands in the radial direction of the gas turbine unit 10 due to a higher temperature in relation to the "cold" side, i.e. the compressor housing 40, during operation of the gas turbine unit. This deforms the shield device, as shown in Figs 4-6. The shield device 20 is supported from the inside at the supporting points 30' on a first or front surface of the stator part, as seen in the fluid flow direction in the gas turbine unit 10. When the stator part expands due to higher temperatures it deforms the end 20' of the shield device from the inside outwards in the radial direction of the gas turbine unit 10, this is more clearly shown in FIG 6. This deformation occurs in that the supporting points of the stator part 30, which are in the form of three shoulders 30', press or push the inner diameter of the right end 20' of the shield device in the radial direction outwards . The shoulders extend a certain distance into the shield device 20 in the axial direction of the gas turbine unit 10; this is more clearly shown in FIG 1 and 3. The three shoulders 30' on the stator part 30 in FIG 4 are evenly distributed around the periphery of the front surface of the stator part. The three shoulders are placed on the same radial distance from the centre axis of the stator part. The three shoulders 30' are symmetrically displaced from each other by an angle of about 120°, preferably.

FIG 5 only shows the shield device 20, the same part of the front surface of the compressor housing 40 shown in FIG 4, the supporting points 40' at the compressor housing, and the rivets 50. FIG 5 shows some of the parts associated with the invention during normal operation of the gas turbine unit 10, as seen in a view from the direction shown with arrows and line B-B in FIG 3. The rivets attach the shield device against the compressor housing. The shield device in this embodiment is attached with its left end 20" to the compressor housing 40 and supported from the outside at this end by six supporting points 40' on the front surface of the compressor housing. The six supporting points are in the form of shoulders ' , which are located symmetrically around the periphery of the compressor housing 40. These shoulders 40' extend a certain distance over the outer surface of the shield device 20 in the axial direction of the gas turbine unit 10, this is more clearly shown in FIG 1 and 3.

The shoulders 40' of the compressor housing 40 in FIG 5 are displaced from each other symmetrically around the periphery of the compressor housing. The angle between the shoulders' in this embodiment is preferably about 60°. This angle may be between 40° and 80° but are most preferably between 55° and 65° as is readily understood by a skilled person. The shoulders' 40' are placed on the same radial distance from the centre axis of the compressor housing. Each of the shoulders' 40' in this embodiment has a thickness that essentially corresponds to the thickness of the shield device 20. The thickness of the shoulders' 30' and 40' may of course have any other size than suggested, the most important is that the thickness fulfils the demands on durability. All six of the shoulders' 40' are placed opposite each other seen in a diametrical direction. Two of the shoulders are placed on the x-axis of a circle if the x-axis extends horizontally through the centre of the circle, and the outer diameter of this circle defines the radial position of each shoulder in FIG 5. This means that one of the shoulders is placed at an angle of 0° and the other is placed opposite at an angle of 180° on the outer contour of this circle.

FIG 6 only shows the shield device 20, the same part of the front surface of the turbine housing 30 shown in FIG 4, the three supporting points 30' at the turbine housing, and the three rivets 50. FIG 6 shows some of the parts associated with the invention during normal operation of the gas turbine unit 10, as seen in a view from the direction shown with arrows and line C-C in FIG 3. The shield device in this embodiment is attached with its right end 20' to the turbine housing 30 and supported from the inside at this end by the three supporting points 30' on the front surface of the turbine housing. The three supporting points are in the form of shoulders', which are located symmetrically around the periphery of the turbine housing 30, as explained with reference to FIG 4.

The number of shoulders 30' on the turbine housing 30, i.e. the stator part, and their positions are chosen so that the thermal expansion of the stator part will deform the right end 20' for the shield device 20 cyclic evenly around its periphery. This embodiment with each of the three shoulders 30' evenly distributed with an angle of 120° around the periphery of the stator part gives a maximum deformation at these positions for the shoulders 30', as seen in FIG 6. This means that three minimum deformation zones occur almost exactly between each of the shoulders. One of these minimum deformation zones is seen adjacent the lowest part of the shield device where the vertical centre line crosses the cross-section. Another minimum deformation zone is seen adjacent the line from the reference mark 20 to the right in FIG 6. A third minimum deformation zone is seen adjacent the line from the reference mark 40 to the left in FIG 6. All of this means that between the maximum and the minimum deformation zones on this right side 20' of the shield device 20 there are points or nodes that experience no deformation or deflection at all. This effect is utilised in the invention by placing all the shoulders 40' on the compressor housing 40 at these positions. Then, the left end 20" of the shield device 20 and the shoulders 40' are loaded as little as possible due to the thermal expansion for the stator part 30 at the other end, i.e. the right end 20' of the shield device. Depending on temperature, the thermal expansion coefficient, and the relationship between the diameter and thickness of the shield device 20 other positions than the nodal positions can be more favourable, as is readily understood by a skilled person. This means that, if e.g. the shield device has a large diameter and a small thickness, the shield device may be deformed in a bulging way during operation of the engine, so that more than six shoulders evenly distributed around the associated end would be required for achieving a satisfactory sealing and durability.

Alternatively, the shoulders 30' on the turbine housing 30, i.e. the stator part, could change places with the shoulders 40' on the compressor housing 40, as is readily understood by a skilled person.

The stator part 30 and the compressor housing 40 could of course be provided with any other number of shoulders 30' and 40', respectively. For example, the shield device 20 could be supported by three shoulders at one end and three shoulders at the other end. The shoulders could of course also have any other positions in the radial direction if required. The shoulders must then be displaced from each other with any other angle depending on the number of shoulders, as is envisaged by a skilled person, but fulfilling the demands of minimum, maximum and/or zero deformation or deflection and durability and sealing. Moreover, the shoulders 30' and/or 40' may also extend in the radial direction instead of the axial direction if designed as ears, lugs or flanges extending in the radial direction. This means for example that the shoulders at one end of the shield device 20 could extend in the axial direction and the shoulders at the other end could extend in the radial direction.

The shield device 20 could of course also be attached with bolts, cylindrical pins or clamping devices instead of rivets against the stator part 30 and the compressor housing 40, as is readily understood by a skilled person. The shield device could of course also have partial flanges at one or even both ends for attachment . The stator part and the compressor housing and associated supporting points, shoulders and/or surfaces may also be press fitted against the shield device. Alternatively, only the stator part 30 or the compressor housing 40 could be press fitted against one end of the shield device 20 while the other end is attached with fastening elements, such as bolts, rivets 50 or cylindrical pins. Associated connecting points or surfaces, especially the shoulders 30' and 40', may also have interlocking designs, e.g. ribs fitting into grooves or bulbs fitting into dents.

Moreover, the shield device 20 could be equipped with the shoulders 30' and 40' instead of attaching them on the stator part 30 and the compressor housing 40, respectively. Then, the stator part and the compressor housing must be provided with grooves or holes for fitting in of the shoulders on the shield device. Furthermore, the stator part and/or the compressor housing can be provided with a complete cylindrical support, i.e. the whole periphery of the supported end 20' and/or 20", instead of only a partial support as in this embodiment .

Optionally, the shield device 20 may also be supported by means of double support as explained earlier, i.e. it could be supported either at one or both ends at both the inside and outside surface, which is readily understood by a skilled person.

Yet another solution for creating a satisfactory sealing at each end 20' and 20" of the shield device 20 is achieved by pressing the turbine housing 30, i.e. the stator part, against the compressor housing 40 or vice versa in the axial direction. This means that when mounting the shield device in the gas turbine unit 10 the fitting between the shield device and adjacent components should be loose so that the mounting is simple. The pressure would keep each end 20', 20" of the shield device tight against its associated part or sealing surface. The prestress or preload against the turbine housing and/or the compressor housing may be achieved by means of springs or high pressure created by gas or air driven devices acting on the associated housing. The springs could be in the form of helical springs, plate or leaf springs or devices similar to preloaded bellows or bilges.

Claims

1. A support/shield device (20) for a gas turbine unit (10) is used for connecting a turbine housing (30) with a compressor housing (40) , the shield device supporting and centering the turbine housing and forming a heat and/or pressure barrier between the turbine housing and the compressor housing, characterised in that the shield device (20) is an essentially rotary symmetrical hollow element attached with a first end (20') to the turbine housing (30) by supports (30') being symmetrically distributed around a front surface of the turbine housing, and in that the supports (30') protrude past the first end (20') of the shield device (20) in the axial direction of the shield device and are in the vicinity of the inner and/or outer surface of the shield device .

2. The support/shield device (20) according to claim 1, wherein the shield device (20) is attached with its second end (20") to the compressor housing (40) by supports (40') being symmetrically distributed around a front surface of the compressor housing, and the supports protrude past the second end of the shield device in the axial direction of the shield device and are in the vicinity of the inner and/or the outer surface of the shield device.

3. The support/shield device (20) according to claim 1 or 2 , wherein the shield device (20) is a hollow element with a small thickness, i.e. the thickness is about 1 to 20% of the diameter of the shield device.

4. The support/shield device (20) according to claim 1, wherein the shield device (20) is a hollow thin cylinder, i.e. the thickness is about 1 to 20% of the diameter of the shield device.

5. The support/shield device (20) according to claim 1, wherein the shield device (20) is attached to the turbine housing (30) by at least two shoulders (30').

6. The support/shield device (20) according to claim 2, wherein the shield device (20) is attached to the compressor housing (40) by at least two shoulders (40') .

7. The support/shield device (20) according to claim

5, wherein the shield device (20) is attached to the turbine housing (30) by means of three shoulders (30') .

8. The support/shield device (20) according to claim

6, wherein the shield device (20) is attached to the compressor housing (40) by means of six shoulders (40') .

9. The support/shield device (20) according to any of the preceding claims, wherein the shield device (20) is attached to the shoulders (30', 40') of the turbine housing (30) and the compressor housing (40) by non-detachable elements, e.g. in the form of rivets (50) .

10. The support/shield device (20) according to any of the claims 1 to 8 , wherein the shield device (20) is attached to the shoulders (30', 40') of the turbine housing

(30) and the compressor housing (40) by detachable elements, e.g. in the form of bolts and/or clamps (50) .

11. The support/shield device (20) according to any of the claims 1 to 8 , wherein the shield device (20) is attached against the turbine housing (30) and the compressor housing (40) by press fitting.

12. The support/shield device (20) according to any of the claims 1 to 8 , wherein the shield device (20) is mounted against the turbine housing (30) and the compressor housing (40) with loose fitting.