EP1033478A2 - Casing for thermal turbomachine - Google Patents

Abstract

The turbomachine housing is divided into 2 housing halves in a plane parallel to the machine axis, each housing half having at least 2 parts (11,12,13) made of different materials which are welded together, having temperature and mechanical loading characteristics matched to the operation of the machine. The different parts of each housing half are positioned one after the other in the axial direction, the 2 housing halves held together by clamp rings (21,22,23), or via screws fitting through abutting flanges.

Description

Technical field

The invention relates to the field of turbine construction. It affects one Housing for a thermal turbo machine, which consists of different Materials.

State of the art

Cast steel housings for thermal turbomachinery are known, especially steam turbines. The housings preferably consist of low-alloyed CrMo or CrMoV cast steel grades. The use of 9 to 13% Cr alloys for turbine housings are also known. Usually are the housing or housing halves, what high temperatures exposed, cast as a whole, i.e. they consist of one Material. Intended production welding or occasionally required Repair welds are made with the same or a Housing material related material executed by the respective cast manufacturer.

Increasing medium temperatures require materials with increasing Alloy contents. On the one hand, this increases the costs for such components, on the other hand, depending on the alloy selected, you also toast Feasibility limits imposed by the casting technology or by the capacity of the Production facility can be given. Because in the future, for example, Steam turbine construction temperatures between 540 ° C and 850 ° C are expected The choice of the right alloy in the right place is a special one Importance too, especially in terms of cost, feasibility and technical Characteristics. The latter concerns, for example, the relative expansion behavior between adjacent parts, such as housing and rotor.

It is known, the rotor of turbomachinery from different disks, which may consist of different material, to weld together. The choice of material depends on the respective Requirements. Where high temperatures prevail, high alloys are used Discs used that are welded together with lower alloy discs as soon as the temperature and the loads allow it.

The disadvantage of using large housings or housing halves, which consist of a single material consists in that z. B. reaches the limits of feasibility when using Ni-based alloys. In addition, the costs are very high because the expensive high or High temperature resistant material is also used in the areas where whose use is not required at all.

Furthermore, the thermal expansions of such a housing harmonize not with those of the wave, with the disadvantage that the games between fixed and rotating parts become bigger than necessary during operation required, which has a negative impact on the efficiency of the machine.

Housings are known from turbine construction, the parts of which are made of different materials. These housing parts are screwed together, d. H. there is a non-positive connection. As For example, combined housings made of cast steel and Ductile iron components are called by means of a flange connection are connected.

The disadvantage of this housing screwed by means of flange connections is in that the flange fittings need space. They are also at Housings that are exposed to higher pressures and temperatures, costly and problematic to seal, especially with cross flanges.

Finally, there is a disadvantage of the known housing with parting line and Separating flanges, which are thicker than the shell, in that the housing through the asymmetrical shape when heated tend to ovalize what is unfavorable on the games between fixed and rotating parts and thus affects the efficiency of the machine.

Presentation of the invention

The invention tries to avoid all these disadvantages. You have the task to develop a turbomachine housing that is inexpensive is to be manufactured, in which the material selection corresponds to the respective Operating conditions is adjusted, the thermal differential expansions between the shaft and housing are minimized and in which an ovalization of the Housing parts can be largely avoided during operation.

According to the invention, this is the case with a turbomachine housing which consists of at least two housing parts made of different materials exists, achieved in that the at least two housing parts by means of a cohesive joining process are joined together and the type of used material the respective temperature requirements and mechanical loads during operation of the machine is adjusted.

The advantages of the invention include that Screw connections between the individual housing parts are eliminated. The joint are mechanically problem-free and tight under all operating conditions. As another Another advantage is that the housing according to the operating requirements is economical to manufacture with optimal materials and thermal Flexibility compared to the state-of-the-art solutions is increased.

It is particularly useful if the housing in the axial direction different materials. The materials for the housing are included matched to the choice of shaft material. This can be advantageous thermal differential expansions between the shaft and the housing are minimized become.

Furthermore, it is advantageous if the housing has different circumferences Materials with different coefficients of thermal expansion consists. This advantageously leads to a reduction in the signs of ovalization of the housing.

As a joining process are advantageous welding processes such. B. Electrode welding by hand, MIG (metal inert gas) and MAG (metal active gas) welding by hand or by machine, submerged arc welding, Electron beam welding or laser beam welding, but also soldering processes intended. Depending on the load and material, they are cohesive Connections of the housing parts can be produced economically.

Brief description of the drawing

In the drawing, several embodiments of the invention are based on single-shaft axially flow-through steam turbines shown.

Fig. 1

einen Längsschnitt einer doppelschaligen Hochdruckturbine in einer ersten Ausführungsvariante der Erfindung;

Fig. 2

einen Querschnitt durch den Zudampf entlang der Linie II-II gemäss Fig. 1;

Fig. 3

einen Querschnitt in der Nähe des Abdampfes entlang der Linie III-III gemäss Fig. 1;

Fig. 4

einen Längsschnitt einer doppelschaligen doppelflutigen Turbine in einer zweiten Ausführungsvariante der Erfindung;

Fig. 5

ein Detail der Flanschverbindung in der Trennebene;

Fig. 6

einen Schnitt senkrecht zur Turbinenachse durch eine beschaufelte Partie eines Gehäuses in einer dritten Ausführungsvariante der Erfindung.

Show it:

Fig. 1

a longitudinal section of a double-shell high-pressure turbine in a first embodiment of the invention;

Fig. 2

a cross section through the vapor along the line II-II of FIG. 1;

Fig. 3

a cross section near the exhaust steam along the line III-III of FIG. 1;

Fig. 4

a longitudinal section of a double-shell double-flow turbine in a second embodiment of the invention;

Fig. 5

a detail of the flange connection in the parting plane;

Fig. 6

a section perpendicular to the turbine axis through a bladed portion of a housing in a third embodiment of the invention.

Only the elements essential for understanding the invention are shown.

Ways of Carrying Out the Invention

The invention is explained below using exemplary embodiments and FIG. 1 to 6 explained in more detail.

Fig. 1 shows in a longitudinal section with a double-shell high-pressure steam turbine a housing according to the invention in a first embodiment of the Invention while FIGS. 2 and 3 cross sections of the high pressure steam turbine represent along lines II-II and III-III in Fig. 1.

The steam turbine essentially consists of one, here four Disks 1, 2, 3, 4 composite shaft that carries the blades 51, an inner housing 11, 12, 13 which carries the guide vanes 50 and one Outer housing 41. The inner housing is in a horizontal plane separated into two housing halves by the turbine axis.

The discs 1, 2, 3 and 4 each consist of different materials. she are according to the known prior art by means of welding connected to one another, as in FIG. 1 using the wave weld seams 5, 6, 7 is recognizable. The disc 1, which highest temperatures (approx. 620 ° C) is made of a high-alloy 9 to 13% Cr steel, for example. The disc 2 is comparatively lower, but still high Exposed to temperatures (approx. 560 ° C). B. from one made of low-alloy CrMoV steel. The discs 3 and 4 only have to can withstand relatively moderate temperatures (approx. 450 ° C) and are therefore from one unalloyed steel.

According to the invention, the inner housing, like the shaft, is now made of different materials Parts, in the present exemplary embodiment from three parts 11, 12, 13 materially joined together, the housing part 11 with the housing part 12 is welded together to form a circular seam 15, and that Housing part 12 at its other end in turn with the housing part 13 below Formation of a housing weld seam (circular seam) 16 is welded together. Electrode welding by hand, MIG, can be used as the welding process and MAG by hand or by machine, submerged arc welding, Electron beam welding or laser beam welding for use come.

The housing part 11 for maximum temperature application consists, for. B. from a 9th up to 13% Cr steel, the housing part 12 is made for high temperature application e.g. B. from a low-alloy CrMoV steel and the housing part 13 for Low temperature application exists e.g. B. from an unalloyed steel. The The inner casing of the high-pressure steam turbine is thus out in the axial direction different materials, the type of material used the respective temperature requirements and mechanical loads in the Operation is adjusted.

The housing parts 11, 12, 13 can, depending on the design and requirements be cast or forged, with the parts 12 and 13 especially for Suitable for forging.

The housing parts can be in the foundry, in the forge or at one suitable suppliers are welded together.

The two housing halves of the inner housing are presented here Embodiment after welding, machining and assembling the Blading held together by shrink rings 21, 22, 23. The Shrink rings 21, 22, 23 are cooled by the exhaust steam flow, so that they do not have to consist of high-alloy expensive materials, but for example from inexpensive forged low-alloy CrMoV steels can exist.

• im Höchsttemperturbereich  (ca. 620...850 °C)   Ni- Basislegierung
• im Hochtemperaturbereich  (ca. 560...620 °C)   9 bis 13%iger Cr-Stahl
• im Niedertemperaturbereich  (ca. 450...560 °C)   CrMoV-Stahl.

When increasing the steam temperatures to z. B. 850 ° C, the individual parts 1, 2, 3, 4 of the shaft and the parts 12, 13, 14 of the inner housing advantageously consist of the following materials, wherein a manufacturing weld is provided between the individual parts:

• in the maximum temperature range (approx. 620 ... 850 ° C) Ni base alloy
• in the high temperature range (approx. 560 ... 620 ° C) 9 to 13% Cr steel
• in the low temperature range (approx. 450 ... 560 ° C) CrMoV steel.

The choice of material for the parts 12, 13, 14 of the inner housing is thus on Choice of shaft material, d. H. parts 1 to 4. For example, goes from Fig. 2, the cross section through the vapor, that the wave washer 1 and part 11 of the inner casing of the steam turbine the same Temperature conditions (highest temperature) are subject and therefore off should be made of the same material, e.g. B. a Ni-based alloy. Fig. 3 shows a cross-section in the vicinity of the exhaust steam, from which shows that the wave washer 3 the same temperature conditions (low temperature) is subjected as the inner housing part 13 and therefore the Parts 3 and 13 advantageously made of the same material, e.g. B. a low-alloy CrMoV steel should be made.

The advantages of the invention are that thermal turbomachines can be built economically at the highest pressures and temperatures. The use of expensive high-alloy materials is to a minimum reduced. The castings are of comparatively modest dimensions, which improves delivery times and has a positive impact on feasibility, Means costs and lead times. In addition, many parts can be advantageous be forged. Technically speaking, parts that pass through Welding is associated with the highest demands.

4 and 5 show a second exemplary embodiment of the invention on the basis of a double-shell, double-flow steam turbine, FIG. 4 a longitudinal section the turbine and Fig. 5 shows a detail of the flange connection in the Dividing plane shows. The steam turbine shown can be both high pressure and also be a medium pressure turbine.

As with the first embodiment described above, each of the Turbines essentially from one of several parts 1, 2, 3, 4 composite shaft, which carries the blades 51, an inner housing 11, 12, 13, which carries the guide vanes 50 and an outer housing 41 Shaft parts 1, 2, 3, 4 are each by means of the weld seams 5, 6, 7 put together while the various housing parts of the inner housing 11, 12, 13 by means of the housing weld seams denoted by 15 and 16 are put together. In contrast to the first embodiment the housing halves not by shrink rings, but by Flange fittings 43 held together. The screw material is in Dependence on the housing material selected. The screw material and that Housing material should have the same coefficient of expansion as possible.

The coat must be welded all around. For welding work to save and ensure the necessary flexibility, the Flange parts not welded through, which can be seen well in FIG. 5.

6 finally shows a third embodiment variant of the invention in a section perpendicular to the turbine axis through a bladed part of a housing. A flange 42 is welded to a housing wall 14 by means of a longitudinal housing seam 17. Depending on requirements, this longitudinal seam 17 can extend over part of the housing length or over the entire length. The thick and thus thermally inert flange parts 42 consist of a material with a higher thermal expansion coefficient than the relatively thin housing wall 14. As a possible example, it should be mentioned here that the separating flange 42 is made of a CrMoV steel with a thermal expansion coefficient of approximately 13x10 ^-6 K ^-1 and the housing wall 14 consist of a 9 to 13% Cr steel with a thermal expansion coefficient of about 11x10 ^-6 K ^-1 . By using materials with different coefficients of thermal expansion over the circumference of the housing, the ovalization effects are at least partially compensated for and an undesired increase in the play between rotating and stationary parts of the machine is prevented.

Of course, the invention is not limited to that described Embodiment limited. The different housing parts can For example, instead of using welding, also joined by soldering his. It is also conceivable for such housings also for others Turbomachinery, e.g. B. gas turbines or axial compressors.

Reference list

1

Shaft part for maximum temperature application

2nd

Shaft part for high temperature application

3rd

Shaft part for low temperature application

4th

Shaft part for low temperature application

5

Corrugated weld

6

Corrugated weld

7

Corrugated weld

11

Housing part for maximum temperature application

12th

Housing part for high temperature application

13

Housing part for low temperature application

14

Housing wall

15

Housing weld seam (circular seam)

16

Housing weld seam (circular seam)

17th

Housing weld seam (longitudinal seam)

21

Shrink ring

22

Shrink ring

23

Shrink ring

41

Outer housing

42

Horizontal separating flange

43

screw

50

Guide blading

51

Barrel blading

Claims (8)

Housing for a thermal turbo machine, which in one plane separated into two housing halves approximately parallel to the machine axis is, each housing half of at least two housing parts (11, 12, 13, 14, 42) consists of different materials, characterized in that the at least two housing parts (11, 12, 13, 14, 42) joined together by means of an integral joining process are and the type of material used each Temperature requirements and mechanical loads during operation is adjusted. Housing for a thermal turbomachine according to claim 1, characterized characterized in that the housing (11, 12, 13) in the axial direction different materials. Housing for a thermal turbomachine according to claim 1, characterized characterized in that the housing (14, 42) over the circumference different materials, each with different thermal Expansion coefficient exists. Housing for a thermal turbomachine according to claim 1, characterized characterized that the joining process is a welding process. Housing for a thermal turbomachine according to claim 1 thereby characterized that the joining process is a soldering process. Housing for a thermal turbomachine according to claim 4, characterized characterized that as the welding process electrode welding by Manual, MIG and MAG by hand or by means of automatic machines, submerged arc welding, Electron beam welding or laser beam welding are provided. Housing for a thermal turbomachine according to claim 1, characterized characterized that the housing halves with the help of shrink rings (21, 22, 23) are held together. Housing for thermal turbomachinery according to claim 1, characterized characterized that the housing halves by means of flange fittings (43) are held together.

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