GB2281592A

GB2281592A - Exhaust gas diffuser for gas turbines

Info

Publication number: GB2281592A
Application number: GB9416985A
Authority: GB
Inventors: Michael Hock
Original assignee: ABB Management AG
Current assignee: ABB Management AG
Priority date: 1993-09-02
Filing date: 1994-08-23
Publication date: 1995-03-08
Anticipated expiration: 2014-08-23
Also published as: GB9416985D0; DE4329623A1; GB2281592B

Description

- I - 2281592 Exhaust gas diffuser

Technical field

The invention relates to an exhaust gas 5 diffuser for gas turbines.

Prior art

Such exhaust gas diffusers are known. They 10 consist of a support structure and a hot-gas guidance structure which prevents the support structure from being heated excessively. The support structure is formed from an inner cylinder and an outer cylinder which are connected together by radial or tangential is struts. The hot-gas guidance structure lines the space between the two cylinders, including the struts. it must therefore be configured, during manufacture, to correspond with the shape of the support structure and must be joined together, during assembly, from two or a plurality. of parts by means of welded connections or plug-in connections.

An essential disadvantage of the known exhaust gas diffusers consists in the fact that the hot-gas guidance structure has to be fitted into the existing support structure during assembly. This takes place by inserting the parts of the prefabricated sheet-metal shell of the hot-gas guidance structure into the sup port structure and -only subsequently joining them together.

Manufacturing the exhaust gas diffuser in such a way is very labour-intensive. In addition, the com ponents of the hot-gas guidance structure can only be welded from the hot-gas side and this raises access problems with respect to the welding work to be carried out and therefore also with respect to its quality. In the case of a plug- in connection, the hot-gas structure is segmented and there are, therefore, a large number of individual hot-gas guidance parts which can only be sealed and joined together within the support structure at great expense& This likewise frequently causes quality problems. These quality shortcomings can have negative effects on the functional reliability of the exhaust gas diffuser.

A further disadvantage of the known exhaust gas diffusers, manufactured in the manner described, con sists in the fact that they cannot be non-destructively opened for inspection and repair purposes.

Description of the invention

The invention attempts to avoid all these disadvantages. It is based on the object of creating a functionally reliable exhaust gas diffuser for gas tur- bines which is relatively easy to assemble and which can also be non- destructively dismantled.

In accordance with the invention, this is achieved in that the support structure consists of a plurality of segments, which form the outer cylinder, are connected together so that they can be released and are each shaped to include at least one strut, and of an inner cylinder which is connected to the struts so that it can be released. The hot-gas guidance structure is provided with openings for the struts.

The advantages of the invention consist mainly in the f act that it is no longer necessary to join together the multi-part hot-gas guidance structure in the assembled condition of the exhaust gas diffuser, as was previously usual. Instead of having to join the hot-gas guidance structure together by welded connections or plug-in connections at locations with difficult access within the exhaust gas diffuser, as was previously the case, this work can now be undertaken before the assembly of the exhaust gas diffuser and, therefore, at locations which can be reached much more easily. In this way, a well-sealed hot-gas guidance structure is obtained for both types of connection and this structure can be installed as a complete unit. After the hot-gas guidance structure has been applied to the inner cylinder, the struts of the outer segments are inserted into the openings of the hot-gas guidance structure and are fastened, so that they can be released, in the inner cyl inder of the support structure. As a consequence of the configuration of the support structure according to the invention, the assembly joints occurring during the final assembly of the exhaust gas diffuser have been displaced from the hot-gas guidance structure into the relatively cold support ' structure where their sealing can be substantially better.

It is particularly expedient for each strut to have, at its free inner end, a spigot which engages, in the assembled conditionr in a correspondingly config- ured assembly groove of the inner cylinder. This also permit s simple and non-destructive dismantling of the exhaust gas diffuser.

Flange connections, known per se, are arranged at the periphery of the outer cylinder between the respectively adjacent segments. In this way. the segments are fastened so that they can be easily released and this likewise contributes to the possibility of non-destructive dismantling of the exhaust gas diffuser.

Brief description of the drawing

An embodiment example of the invention is represented in the drawing, using an annular exhaust gas diffuser.

In the drawing:

Fig. 1 shows a longitudinal section through the exhaust gas diffuser; 35_ Fig. 2 shows a' section through the exhaust gas dif- fuser along the line A-A in Fig. 1.

Only the elements essential to understanding the invention are shown. Not shown, for example, are the gas turbine and the chimney connected to the exhaust gas diffuser and the gas turbine shaft bearing system arranged within the inner cylinder - The flow direction of the working medium is indicated by arrows.

Method of carrying out the invention The exhaust gas diffuser 1 consists of a support structure 2 and a hot- gas guidance structure 3.

The support structure 2 is f ormed from a plurality of segments 4, which are connected together so that they can be released and which each have a strut 5, and an inner cylinder 6 which is connected to the struts 5 so that it can be released. The outer cylinder 7 consists of the totality of the segments 4 when they are connected together. The hot-gas guidance structure 3 is provided with openings 8 for the struts 5 (Fig. 2). Each strut 5 has,, at its free inner end,, a spigot 9 which engages, in the assembled condition, in a correspondingly configured assembly groove 10 of the inner cylinder 6 (Fig. 1).

The adjacent segments 4 are held together in the peripheral direction by means of flange connections 11. These each consist of two flanges 14 which, in the assembled condition, are located immediately adjacent to one another, are provided with holes 12 and are connected together by bolts 13.

Because the support structure 2 is arranged so that it can be released, the hot-gas guidance structure 3 can be joined together in a well-sealed condition before the final assembly of the exhaust gas diffuser 1 and can be installed as a complete unit. Af ter the hot-gas guidance structure 3 has been applied to the inner cylinder 6, as is represented in Fig. 2,, the struts 5 of the segments 4 are inserted into the openings 8 of the hot- gas guidance structure 3 and are fastened by means of the spigots 9 of the struts 5 into the assembly grooves 10 of the inner cylinder 6. In order to form a stable outer cylinder 7, the connection 93/105 of the segments 4, which are arranged adjacent to one anotherr then takes place by introducing the bolts 13 into the holes 12 of the flanges 14.

Dismantling the exhaust gas diffuser 1 for inspection and repair purposes takes place in the reverse order.

List of designations 1 Exhaust gas diffuser 2 Support structure 3 Hot-gas guidance structure 4 Segment Strut 6 Inner cylinder 7 outer cylinder 8 Opening 9 Spigot Assembly groove 11 Flange connection 12 Hole 13 Bolt 14 Flange 93/105 -4 -

Claims

1. Exhaust gas diffuser for gas turbines, which consists of a support structure and a hot-gas guidance structure, the support structure being formed from one inner and one outer cylinder connected together by radial. or tangential struts and the hot-gas guidance structure lining the space between the two cylinders, including the struts, characterized in that the support structure consists of a plurality of segments F which form the outer cylinder I are connected together so that they can be released and are each shaped to include at least one strut, and of an inner cylinder which is connected to the struts so that it can be released, and in that the hot-gas guidance structure is provided with openings for the struts

2. Exhaust gas diffuser according to Claim 1, characterized in that each strut has, at its free inner end, a spigot which engages, in the assembled condition, in a correspondingly configured assembly groove of the inner cylinder

3. Exhaust gas diffuser according to Claim 1 and 2, characterized in that flange connections, known per se, are arranged at the periphery of the outer cylinder between the respectively adjacent segments

4. A gas turbine exhaust gas diffuser substantiaffy as herein described with reference to the accompanying drawings.