EP1895094B1 - Swirl cooled rotor welding seam - Google Patents

Abstract

The turbo machine has a rotor rotatably supported within a housing, where the rotor is formed of two partial rotors that are welded with one another to form a welding area. A cover strap (6) and spin bores (12) are provided for cooling the welding area, and a guide vane row with guide vanes (7) formed with the cover straps. The cover strap is designed with the spin bores for guiding flowing medium, which flows through the turbo machine during operation on the welding area. One of the partial rotor is formed from a chrome material.

Description

The invention relates to a turbomachine comprising a housing and a rotatably mounted within the housing rotor, wherein the rotor is formed of two part rotors and the two part rotors are welded together, whereby a welding area is formed.

In steam turbine construction, it is necessary to form steam turbines for steam inlet temperatures of over 600 ° C. Efforts are currently being made to form steam turbines for steam inlet temperatures of up to 700 ° C and pressures up to 350 bar. For these high-temperature steam turbines as an embodiment of a turbomachine increasingly welded rotors are used. The welded rotors are characterized by the fact that they have a highly heat-resistant alloy in a region which is subjected to high thermal loads and is exposed to lower thermal stresses in a region having a rotor material which has low heat-resistant properties and is thus more cost-effective.

To increase the efficiency of a steam turbine, the use of steam at higher pressures and temperatures helps. The use of steam with such a steam condition places increased demands on the corresponding steam turbine.

For the purposes of the present application, a steam turbine is understood to mean any turbine or sub-turbine through which a working medium in the form of steam flows. In contrast, gas turbines are traversed with gas and / or air as a working medium, but that is subject to completely different temperature and pressure conditions than the steam in a steam turbine. Unlike gas turbines instructs Steam turbines, for example, the working medium having the highest temperature, which flows to a partial turbine, at the same time has the highest pressure. An open cooling system, as in gas turbines, is therefore not feasible without external supply. A steam turbine typically includes a vaned rotatably mounted rotor disposed within a casing shell. When flowing through the flow space formed by the housing jacket with heated and pressurized steam, the rotor is set in rotation by the steam via the blades. The rotor-mounted blades are also referred to as blades. In addition, usually stationary guide vanes are mounted on the housing jacket, which engage in the intermediate spaces of the moving blades. A vane is typically held at a first location along an interior of the steam turbine casing. In this case, it is usually part of a vane ring, which comprises a number of vanes, which are arranged along an inner circumference on the inside of the steam turbine housing. Each vane has its blade radially inward. A vane ring at a location along the axial extent is also referred to as a vane row. Usually, a plurality of vane rows are arranged one behind the other.

An essential role in increasing the efficiency plays the cooling. In the previously known coolant methods for cooling a steam turbine housing is to distinguish between an active cooling and a passive cooling. In the case of active cooling, cooling is effected separately by means of a steam turbine, ie, in addition to the working medium, supplied cooling medium. In contrast, a passive cooling is done only by a suitable leadership or use of the working medium. A known cooling of a steam turbine housing is limited to a passive cooling. For example, it is known to flow around an inner casing of a steam turbine with cool, already expanded steam. However, this has the disadvantage that a temperature difference over the Innengehäusewandung remain limited otherwise, if the temperature difference were too great, the inner casing would thermally deform too much. Although a heat dissipation takes place in a flow around the inner housing, the heat removal takes place relatively far away from the point of heat supply. A heat dissipation in the immediate vicinity of the heat supply has not been realized in aüsreichenendem extent. Another passive cooling can be achieved by means of a suitable design of the expansion of the working medium in a so-called diagonal stage. However, this can only achieve a very limited cooling effect on the housing.

The rotatably mounted in the steam turbine steam turbine rotors are subjected to thermal stress during operation. The development and production of a steam turbine rotor is both expensive and time consuming. The steam turbine rotors are considered to be the most highly stressed and expensive components of a steam turbine.

A feature of the steam turbine rotor is that it has no significant heat sink. Therefore, the cooling of the blades arranged on the steam turbine rotor is difficult.

In the EP 1 536 102 discloses a rotor for a steam turbine, wherein the rotor consists of at least two rotor parts. The two rotor parts are welded together, wherein cooling means are provided for cooling the weld area.

The CH 353 218 discloses a runner composed of individual disks designed as a blade carrier of an axial turbine.

The EP 1 013 879 also discloses a shaft of a heat engine with a cavity.

In the US 2003/084568 a method of manufacturing a rotor is shown.

The piston and inflow areas are particularly thermally stressed in the steam turbine rotors. Piston area is to be understood as the area of a thrust balance piston. The thrust balance piston acts in a steam turbine such that a force caused by the working medium force is formed on the rotor in one direction counter-force in the opposite direction.

It would be desirable to be able to form a rotor for a turbomachine that requires as few amounts of expensive high-temperature alloy, thereby becoming cheaper to manufacture.

At this point, the invention begins, whose task is to specify a turbomachine, which can be manufactured inexpensively.

The object is achieved by a turbomachine, comprising a housing and a rotatably mounted within the housing rotor, wherein the rotor is formed of two part rotors and the two part rotors are welded together, whereby a welding area is formed, wherein cooling means are provided for cooling the welding area ,

The turbomachine comprises at least one row of guide vanes having vanes formed with shrouds, the shroud having swirl bores for guiding a flow medium flowing in operation through the turbomachine to the weld area.

The invention therefore provides for a turbomachine with a rotor, which is formed from two part rotors. During operation, the two sub-rotors experience different thermal stresses. One of the two sub-rotors can be used in a particularly thermally loaded area, whereas the second sub-rotor is to be used in a comparatively less thermally stressed area. The welding must be done at a suitable place. Care must be taken to ensure that the thermal load on the welding area during operation is not too great. Therefore, efforts are made to move the welding area as possible to a point that is relatively less thermally stressed. According to the invention, it is proposed to arrange the welding area entirely in a region of higher thermal stress. In order for the rotor to withstand the thermal stresses, coolant for cooling the weld area is provided according to the invention.

Thus, the welding area can be arranged in an area on the rotor, which is exposed to higher thermal loads. Due to the cooling according to the invention, the weld can nevertheless be arranged in this thermally loaded area. As a result, the heat-resistant material to be used in the thermally stressed area can be saved, since the weld is arranged as far as possible in the thermally stressed area. In the less thermally loaded area can be a cheaper, less heat-resistant material can be used. Due to the material savings of expensive high-temperature resistant material finally the production of such a turbomachine is cheaper.

Particularly cost-saving, the invention has an effect if the sub-rotor, the high thermal loads of about 700 ° C is exposed, made of a nickel-based alloy. The material price of these alloys is a factor of three to four higher than that of material X12 (i.e., a 9% chromium steel) used for the part rotor exposed to low thermal stresses.

In addition, the allowable dimensions of the forgings are limited. The maximum billet weight of a nickel-based alloy forging is currently 6 t, whereas the maximum billet weight of a forged billet of X12 is> 12 t.

Any reduction of the partial rotor of the nickel-based alloy already by a few centimeters leads to significant cost savings and, moreover, such a part rotor can be procured easily. According to first estimates, such a rotor designed according to the invention could save up to 20% or up to 50 cm of the length of this partial rotor not designed according to the invention.

Advantageous developments are specified in the subclaims.

It is inventively provided that a shroud with swirl holes for guiding a flowing during operation by the flow machine flow medium is carried out on the welding area. During operation, the flow medium flows through the swirl bores. Due to the accelerating effect in the swirl bore, the temperature of the flow medium in the swirl hole is reduced. This means that after exiting the swirl hole, the flow medium acts as a cooling medium. With the thus cooled flow medium finally the welding area of the rotor is cooled.

So it is advantageous if the shroud is arranged above the welding area. It has a favorable effect if the shroud is arranged in the immediate vicinity above the welding area. The flowing out of the swirl holes flow medium acts as a cooling medium and should therefore be placed as close to the welding area.

Advantageous in the context of the invention is when the swirl hole in a region of the shroud, which is seen in the flow direction in front of the Leitschaufelvorderkante is arranged.

The flow conditions of the flow medium in the turbomachine are such that it is favorable that the swirl bore is arranged before the flow medium enters the guide vane row. Thus, it is possible to divert a high volume flow of the flow medium into the swirl bores.

In an advantageous development, the swirl bore is inclined at an angle α to the flow direction. The angle α has values between 30 ° and 90 °. This makes it possible, due to the flow conditions in the flow channel, to divert a high yield of volume flow from the flow medium in the flow channel into the swirl bore.

In a further advantageous embodiment, the swirl bore is inclined at an angle β to the tangents of the Leitschaufeldeckbandoberfläche. The angle β has values between 0 ° and 60 °. As tangential of the Leitschaufeldeckbandoberfläche is essentially a straight line to understand that leads perpendicular to a connecting line from the rotor center to the swirl hole and branches off from the swirl hole. This makes it possible to achieve the so-called swirl cooling, which is reinforced by the inventive inclination of the swirl bore. In addition, the swirl cooling is caused by the interplay between a moving reference system (rotating rotor) and a stationary reference system (Leitschaufelreihe).

In an advantageous development, a rotor seal is arranged in the front region of the shroud. As a result, it is possible for as little as possible flow medium to flow with loss between the shroud and the rotor surface. This has the advantage that on the one hand the overall efficiency of the turbomachine is increased and secondly, the hot flow medium would be kept away from the welding area.

In the following an embodiment of the invention will be described in more detail with reference to a drawing. In this case, mutually equivalent components have the same reference numerals.

FIG 1

eine Querschnittsansicht eines Teiles einer Strömungsmaschine,

FIG 2

eine Querschnittsansicht (in Strömungsrichtung) gesehen eines Teiles der Strömungsmaschine,

FIG 3

eine Draufsicht auf eine aufgewickelte Leitschaufelreihe,

FIG 4

eine vergrößerte Querschnittsansicht eines Teiles aus FIG 1.

Show it

FIG. 1

a cross-sectional view of a part of a turbomachine,

FIG. 2

a cross-sectional view (in the flow direction) of a part of the turbomachine,

FIG. 3

a plan view of a wound Leitschaufelreihe,

FIG. 4

an enlarged cross-sectional view of a part FIG. 1 ,

In the FIG. 1 is a cross-sectional view of a turbomachine 1 is shown. A turbomachine 1 is z. B. a gas turbine or a steam turbine. The turbomachine comprises a housing 2. The housing 2 may be formed as an inner housing or as an outer housing. Furthermore, the turbomachine 1 has a rotatably mounted within the housing 2 rotor 3. The rotor is one in the FIG. 1 not shown in detail rotation axis 24 rotatably mounted. The rotor 3 has a first part rotor 3a and a second part rotor 3b. The rotor 3 is welded together in a welding area.

The turbomachine 1 comprises at least one row of guide vanes 5, the row of vanes 5 having vanes 7 formed with shrouds 6.

In the FIG. 1 shown turbomachine has a plurality of vane rows 5 ', 5'',5''' on. Between the guide blade rows 5, 5 ', 5'',5''' blade rows 8 are arranged, which are formed from individual blade 9. In operation, a flow medium flows through the turbomachine 1 in a flow direction 10. The flow medium flows through a flow channel 11.

The flow medium may be, for example, a live steam having temperatures of up to 700 ° C and a pressure of 350 bar. In particular, the turbomachine 1 can be designed as a high-pressure steam turbine.

The shroud 6 is formed with swirl bores 12 for guiding a flow medium flowing through the turbomachine 1 during operation onto the welding region 4. This creates the so-called swirl cooling in the area of the welding area 4 and cools it effectively.

The shroud 6 is arranged above the welding area 4.

In the FIG. 4 is an enlarged view of a part of FIG. 1 illustrated turbomachine 1. In particular, the shroud 6 is shown. The vane 7 comprises a vane profile 13. In the FIG. 3 the guide blade profile 13 can be seen only as a projection on a plane parallel to the flow direction 10. The vane profile 13 is projected at the character level, so to speak. The shroud 6 has a length 14 which is longer than the projection 15 of the guide blade profile 13 on a plane parallel to the flow direction 10.

The swirl bore 12 is arranged in a region 16 of the shroud 6, which is seen in the flow direction 10 in front of the guide blade leading edge 17.

The swirl bore 12 is inclined at an angle α to the flow direction 10. Starting from the flow direction 10, the swirl bore 12 is rotated in the mathematically negative sense by the angle α. The angle α here takes on values between 30 ° and 90 °.

When the drilling operation is carried out from the bottom of the cover plate, the angle α may be 90 °. The airfoil causes no restriction.

The shroud 6 has a projection 18 which faces towards the rotor surface 19. In the front region of the shroud 6, a seal 20 is arranged. The seal 20 may be formed as a labyrinth seal 21 or as a brush seal 22.

In the FIG. 2 is a cross-sectional view (seen in the flow direction 10) of the turbomachine 1 is shown. The rotor 3 rotates in a direction of rotation 23. The direction of rotation 23 points in a clockwise direction. The rotation takes place about a rotation axis 24. The swirl bore 12 is inclined at an angle β to a tangential 25 of the Leitschaufeldeckbandoberfläche 26. The angle β can have values between 10 ° and 60 °.

In the FIG. 3 is a wound Leitschaufelreihe 5, so to speak. The swirl hole 12 is designed as a bore. However, other embodiments of the swirl bore 12 can be considered. The swirl hole 12 may also have a curved course.

The first part rotor 3a is formed of a high heat resistant 1% chromium material. The second partial rotor 3b may be formed of a less thermally loaded and cheaper material.

Claims (14)

1. Turbomachine (1), comprising a housing (2) and a rotor (3) rotatably mounted inside the housing (2), the rotor (3) being formed from two part-rotors (3a, 3b), and the two part-rotors (3a, 3b) being welded to one another, with the result that a weld region (4) is formed, coolant (6, 12) for cooling the weld region (4) being provided, the turbomachine (1) comprising at least one guide-vane row (5), the guide-vane row (5) having guide vanes (7) formed with shrouds (6), characterized in that the shroud (6) is designed with swirl bores (12) for guiding onto the weld region (4) a flow medium which flows through the turbomachine (1) during operation.
2. Turbomachine (1) according to Claim 1, the shroud (6) being arranged above the weld region (4).
3. Turbomachine (1) according to Claim 1 or 2, the length (14) of the shroud (6), as seen in the direction of flow (10), being longer than the length of the projection (15) of the guide-vane profile (13) onto a plane parallel to the direction of flow (10).
4. Turbomachine (1) according to Claim 3, the swirl bore (12) being arranged in a region of the shroud (6) which lies upstream of the guide-vane leading edge (17), as seen in the direction of flow (10).
5. Turbomachine (1) according to either one of Claims 3 and 4, the swirl bore (12) being inclined at an angle α to the direction of flow (10).
6. Turbomachine (1) according to Claim 5, the angle α having a value of between 30° and 90°.
7. Turbomachine (1) according to one of Claims 1 to 6, the swirl bore (12) being inclined at an angle β to a tangential line (25) of the guide-vane shroud surface.
8. Turbomachine (1) according to Claim 7, the angle β having a value of between 10° and 60°.
9. Turbomachine (1) according to one of Claims 1 to 8, the shroud (6) having at the front region (16), as seen in the direction of flow (10), a projection (18) which points towards the rotor surface (19).
10. Turbomachine (1) according to Claim 9, the front region (16) comprising a rotor seal (20).
11. Turbomachine (1) according to Claim 10, the rotor seal (20) being designed as a labyrinth seal (21) or brush seal (22).
12. Turbomachine (1) according to one of the preceding claims, the first part-rotor (3a) being formed from a heat-resistant 1% chrome material.
13. Turbomachine (1) according to one of the preceding claims, designed as a steam turbine.
14. Turbomachine (1) according to one of the preceding claims, the turbomachine (1) being designed as a high-pressure steam turbine.

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