TURBINE HOUSING WITH WALL CLADDING

Abstract

A turbine housing for a turbine is provided. The turbine housing includes a wall cladding on an inner wall of the turbine housing. In a region of joint flanges, the wall cladding is arranged and embodied such that the wall cladding reduces convective heat transfer and thermal radiation in a region of the joint flanges.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of German Patent Application No. 10 2009 037 413.2 DE filed Aug. 13, 2009, which is incorporated by reference herein in its entirety.

FIELD OF INVENTION

The invention relates to a turbine housing, in particular a steam turbine, which consists of a turbine housing lower part and a turbine housing upper part, which are joined together in the assembled state and in this way each embody a joint at their joining areas, with each turbine housing part comprising a joint flange in the region of the joint, by way of which the turbine housing parts are screwed to one another by means of joint screws.

BACKGROUND OF INVENTION

The exterior housings of turbine housings are usually embodied in two parts and include a turbine housing lower part and a turbine housing upper part. The two part embodiment of the turbine housing facilitates assembly of the rotor. The turbine housing lower part and the turbine housing upper part are joined to one another in the assembled state by way of joining areas. The turbine housing lower part and the turbine housing upper part herewith each form a joint at their joining areas. In the region of the joint, the turbine housing parts comprise a joint flange, by way of which the turbine housing parts are screwed to one another by means of joint screws.

In the region of the joints, leakages frequently occur during operation of the turbine, so that in the case of a steam turbine, hot steam can escape outwards through the joint. The leakages herewith occur particularly between adjacent chambers of the turbine housing. The reasons behind the leakage are in particular the high temperature differences between the adjacent chambers, and as a result of the temperature distribution within the turbine housing parts. The component temperature distribution is influenced in a decisive fashion here by way of the fluid temperature, the convective heat transfer between the fluid and the housing parts and by way of the thermal radiation. The wall thickness of the housing parts is non-uniform on account of the joint flange, as a result of which a non-uniform temperature distribution and thus stresses appear in the component, which result in leakages in the joint area.

The problem was previously solved by way of the size, arrangement, material selection and pre-stressing of the joint screws and/or by changing the thermodynamic parameters.

SUMMARY OF INVENTION

An object of the invention is to achieve a sealing of the joints which is simpler and improved by comparison with the prior art.

The object is achieved by a turbine housing as claimed in the independent claim. Advantageous embodiments and developments, which can be used individually or in combination with one another, form the subject matter of the dependent claims.

The inventive turbine housing, including a turbine housing lower part and a turbine housing upper part, which are joined to one another in the assembled state, and herewith each faun a joint on their joining areas, with each turbine housing part in the region of the joint having a joint flange, by way of which the turbine housing parts are screwed to one another by means of joint screws, is characterized in that a wall cladding is provided on an inner wall of the turbine housing, in the region of the joint flange, said wall cladding being arranged and embodied such that it reduces the convective heat transfer and the thermal radiation in the region of the joint flange. The reduction in the convective heat transfer and the thermal radiation in the region of the joint flange results in a reduction in the axial temperature gradient and also enables a reliable sealing of the turbine housing in the region of the joints in the event of high temperature differences between adjacent chambers. The wall cladding is a simple and effective measure here.

An advantageous embodiment of the invention provides that the wall cladding essentially consists of a metallic material. The metallic material is cost-effective, can be easily manufactured and easily fastened to the inner wall of the turbine housing. If necessary, a damaged wall cladding can be easily replaced, since metallic materials are easy to obtain and to process on site.

A particularly preferred embodiment of the invention provides for the wall cladding to be fastened to the inner wall of the turbine housing by means of a thermoelastic fastening. The thermoelastic fastening of the wall cladding ensures that no stresses result in the wall cladding as a result of temperature gradients, which may possibly result in damage to the wall cladding and/or which may destroy and/or damage the fastening to the inner wall.

A particular embodiment of the invention provides for the thermoelastic fastening to take place by means of screwing. The screwing can be embodied very easily and provides for a durable and reliable fastening of the wall cladding to the inner wall of the turbine housing and/or turbine housing part.

The screwing particularly preferably takes place by means of at least one distance screw. The distance screw ensures that the wall cladding does not rest directly against the turbine housing part. A gap is herewith achieved between the wall cladding and the turbine housing, which provides for an improved shielding against convective heat transfer and thermal radiation.

A further preferred embodiment of the invention provides that the respective wall cladding extends through a circumferential angle α of 30° to 60°, measured from the respective joint. A wall cladding embodied in such a way provides for adequate protection of the joint while simultaneously requiring minimal material usage. A wall cladding with a larger circumferential angle is nevertheless possible, but would however only contribute to an insignificant improvement. In the case of a smaller circumferential angle of the wall cladding, the protection in the region of the joint would only be insufficient, so that leakages in the region of the joint cannot be ruled out effectively and reliably.

A further preferred embodiment of the invention provides that the wall cladding extends in the axial direction across one to three divisions in the joint screws. An adequate coverage of the joint is herewith ensured and the material requirement is reduced to the necessary minimum. A larger wall cladding would not contribute to an improvement in the sealing in the joint region. By contrast, a reduction in the axial extension of the wall cladding would result in it not being possible to ensure a reliable sealing of the joint.

The idea underlying the inventive turbine housing is that the convective heat transfer and the thermal radiation from the fluid to the turbine housing wall can be effectively reduced by means of a simple wall cladding in the region of the joint, as a result of which leakages in the region of the joints can be prevented in a simple and cost-effective fashion. Such a wall cladding can be used in particular for steam turbine housings, where leakage problems frequently occur in the region of the joint and have to be reduced with significant effort.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments and further advantages of the invention are described below with the aid of the drawings, in which:

FIG. 1 shows a schematic representation of a three-dimensional section through an inventive turbine housing;

FIG. 2 shows a schematic representation of a radial section through the inventive turbine housing.

DETAILED DESCRIPTION OF INVENTION

The figures illustrate very simplified representations in each instance, in which only the essential components needed to describe the invention are shown. Identical and/or functionally identical components are provided with the same reference characters throughout all the figures.

FIG. 1 shows a three-dimensional section through an inventive turbine housing. The turbine housing 1 includes a turbine housing lower part 2 and a turbine housing upper part 3. The two turbine housing parts 2, 3 are joined to one another in the assembled state. Joints 4 thereby form on the joining areas in each instance. To ensure that no fluid can escape outwards from the interior of the turbine housing 1, the joints 4 must be closed in as tight a fashion as possible. To this end, the turbine housing lower part 2 and the turbine housing upper part 3 are fixedly screwed to one another. To enable a good screwing connection between the two turbine housings 2 and 3, both turbine housing parts comprise joint flanges 5, 6 in each instance. Joint screws 11 (not apparent in FIG. 1) are arranged in the joint flanges 5, 6. The turbine housing 1 is sealed by means of the screw connection of the two turbine housing parts 2, 3. Webs 12 for receiving the fixed blade carrier are provided at different points on the interior of the outer housing. Different chambers 13, 14 are embodied within the turbine housing 1 by means of the guide vanes. High temperature differences exist between the individual chambers 13, 14. The high temperature differences between adjacent chambers 13, 14 brings about a different component temperature and/or component temperature distribution, which result in different expansions of the components, as a result of which leakages occur in the region of the joint 4. The component temperature distribution is influenced in a decisive fashion by the fluid temperature, the convective heat transfer between the fluid and the components and by the thermal radiation. To prevent leakages as a result of the different expansions of the components, a minimization of the axial temperature gradient in the joint flange region is needed. The minimization of the axial temperature gradient in the joint flange region is achieved by means of a wall cladding 8. The wall cladding 8 is arranged and embodied such that it significantly reduces the convective heat transfer and thermal radiation in the region of the joint flange 5, 6. The different expansion of the components is herewith significantly reduced and a reliable sealing in the region of the joint flange 4 is achieved. The embodiment of the wall cladding 8 is shown in detail in FIG. 2 and is described in more detail below.

FIG. 2 shows a radial section through the turbine housing 1, as already described in more detail in FIG. 1. To minimize the axial temperature gradients in the joint flange region, a wall cladding 8 is provided on the inner wall 7 of the turbine housing 1, in the region of the joint flange 5, 6. The wall cladding 8 essentially consists of a metallic material. Other heat-resistant materials can naturally also be used. The wall cladding 8 is fastened to the inner wall 7 of the turbine housing parts 2, 3 by means of a thermoelastic fastening 9. The thermoelastic fastening 9 ensures that the wall cladding 8 is not damaged in the event of an expansion as a result of thermal expansion. In the present exemplary embodiment, the wall cladding 8 is embodied in two parts, with one wall cladding 8 being provided in each instance to shield a joint flange 5, 6.

The invention nevertheless also includes one-piece wall claddings, which extend across both joint flanges 5, 6. In contrast to the one-part embodiment, the two part embodiment is only advantageous in terms of a simpler assembly and disassembly of the turbine housing upper part 2 and the turbine housing lower part 3. The thermoelastic fastening 9 takes place by means of a screw connection 10. The screw connection 10 takes place here at one end of the wall cladding 8. The other end of the wall cladding 8 can be directly welded to the corresponding housing part. The screw connection 10 takes place here by means of at least one distance screw 11. The use of a distance screw 11 achieves a certain distance between the wall cladding 8 and the inner wall 7 of the turbine housing 1. The heat transfer from the wall cladding 8 to the joint flange 5, 6 is significantly reduced by the intermediate space between the wall cladding 8 and the inner wall 7 of the turbine housing 1. A heat transfer can thus only take place by way of the distance screw 11 and the welding point. The thermal radiation from the wall cladding to the joint flange 5, 6 is significantly less than thermal radiation without the wall cladding.

The wall cladding 8 therefore significantly reduces both the convective heat transfer and also the thermal radiation in the region of the joint flange, as a result of which the axial temperature gradient in the joint flange region is minimized and a reliable sealing of the joint 4 is achieved. The respective wall cladding 8 extends, in the case of a two part embodiment, preferably through a circumferential angle α of approximately 30° to 60°, measured from the respective joint 4. With a smaller circumferential angle α of the wall cladding, the thermal shield is reduced, as a result of which a reliable sealing of the joint 4 cannot be ensured. Larger circumferential angles α of above 60° do not bring out about appreciable advantage relative to the shielding. In the axial direction, the wall cladding 8 should extend across approximately one to three divisions of the joint screws in order to ensure a reliable shielding and thus sealing of the joints 4. The wall cladding 8 is arranged axially between 2 chambers of the turbine housing 1 in each instance.

By means of the inventive turbine housing 1 having a wall cladding 9 arranged on the inner wall 7 of the turbine housing 1, it is thus possible to minimize the axial temperature gradients in the joint flange region by means of an inner thermal shielding in a simple and cost-effective fashion. The leakage of the joint 4 is herewith increased considerably and the operational reliability is improved. The turbine housing 1 with the wall cladding 8 can be used particularly effectively for steam turbines. It is however basically suited to any type of turbine housing. Retrofitting of the already existing turbine housing is possible.

Claims

1.-7. (canceled)

8. A turbine housing, comprising:

a turbine housing lower part and a turbine housing upper part, each turbine housing part foaming a joint at a joining area when the turbine housing part are in an assembled state,

wherein each turbine housing part comprises a joint flange in a region of the joint, and wherein the turbine housing parts are screwed to one another by joint screws via the joint flanges; and

a wall cladding on an inner wall of the turbine housing, wherein the wall cladding is arranged and embodied in the region of the joint flanges such that the wall cladding reduces a convective heat transfer and a thermal radiation in the region of the joint flanges.

9. The turbine housing as claimed in claim 8, wherein the wall cladding essentially consists of a metallic material.

10. The turbine housing as claimed in claim 8, wherein the wall cladding is fastened to the inner wall of the turbine housing part by a thermoelastic fastening.

11. The turbine housing as claimed in claim 9, wherein the wall cladding is fastened to the inner wall of the turbine housing part by a thermoelastic fastening.

12. The turbine housing as claimed in claim 10, wherein the thermoelastic fastening comprises a screw connection.

13. The turbine housing as claimed in claim 11, wherein the thermoelastic fastening comprises a screw connection.

14. The turbine housing as claimed in claim 12, wherein the screw connection includes at least one distance screw.

15. The turbine housing as claimed in claim 13, wherein the screw connection includes at least one distance screw.

16. The turbine housing as claimed in claim 8, wherein the wall cladding extends across a circumferential angle α of 30° to 60°, measured from the respective joint.

17. The turbine housing as claimed in claim 8, wherein the wall cladding extends in an axial direction across one to three divisions of the joint screws.