EP2025882A1 - Casing assembly for a stationary turbo engine - Google Patents

Abstract

The arrangement has flange-shaped housing components (10, 12) that lie against each other and are screwed together. The component (12) has recesses (26, 28) for a screw connection (22). The screw connection has a tensioning bolt (24) that extends through the receptacles, where the bolt fits with a space (36) in the receptacles. The space is partially filled with a heat conductive filler material (42) e.g. metal wool, steel wool, copper wool or a metallic granulate. The filler material heat-technically couples a cylindrical surface (38) of the bolt and side walls (40) of the recesses.

Description

The invention relates to a housing arrangement for a stationary turbomachine, with two flange-like abutting, screwed together housing components, of which at least one of the two housing components for each one the two housing components together screwing a receptacle, each screw has a extending through the receptacle clamping bolt includes, which sits with a radial clearance in the recording.

Flange-like housing top and bottom parts of stationary turbomachines are known from the prior art, which are connected by a plurality of fittings tightly together. Each of these fittings includes a clamping bolt extending through aligned holes in the flanges. On both sides of the flanges, the clamping bolt is provided with nuts, whereby the two flanges are pressed firmly together. Possibly. There are still washers between the nuts and the flanges of the housing components. To achieve a positive connection, the two flanges, large preloads for the fittings are required so that the clamping bolt in the bolted state and without operating stress (without higher temperature and operating pressure) already reach their yield strength.

If relatively high temperatures occur inside the housing, the Flanschverschraubungen are mechanically and thermally stressed in a special way. The load is greater, the greater the difference of the wall thicknesses of the housing and the flanges. When heating the case of a cold start still cold housing of the turbomachine, the heat is distributed from inside out. Accordingly, the material expansions of the different massive housing areas during the heating process are different in size. The material areas of the housing immediately surrounding the interior are heated as first regions of the housing and therefore expand first. The outer layers of the housing are heated only gradually due to the cooler ambient temperature, so that their thermal expansions initially have a lesser extent. This effect is in the area of the flanges with their additional wall thickening resp. Material accumulations even stronger. The clamping bolts heat up only very delayed compared to the housing, since these are only connected via the nuts and the flanges with the heat source inside the housing. At the same time, the bolting surface between screw thread and nut represents the smallest contact surface and thus the largest heat flow resistance in the path from heat source to clamping bolt. Consequently, the bolt is heated much slower than the homogeneous material of a non-pierced flange in a comparable position. Due to the thermal expansions of the flanges of the housing components, the initially still cool clamping bolts are further stretched. This can at the first commissioning resp. during a cold start of the turbomachine cause the clamping bolts are stretched so that sets a plastic deformation. This is accompanied by a loss of bias, which can lead to leaks in the flange connection.

Further, due to the fact that the housing is delayed from inside to outside, a bending load of the prestressed bolts occurs, which further increases the overall load. Overall, the size of the contact pressure of the housing assembly is thereby reduced, so that in the worst case, the flange can also be leaking. Then losses occur in the housing guided working medium, which are to be avoided in principle.

In addition to the described overstretching of the clamping bolt and the resulting loss of bias, caused by the inhomogeneous thermal expansions also in the housing wall, respectively. in the flanges themselves, local voltage peaks. These can cause a fatigue crack to develop, which then progresses with each subsequent cold start.

In particular, the aforementioned symptoms occur in the housings of heavy stationary gas turbines and high pressure, medium pressure and low pressure steam turbines. These have the aforementioned housing arrangements, wherein the two housing components screwed together can be, for example, a lower housing half and an upper housing half. Likewise, the two screwed together housing components may also be parts thereof, for example, if the upper resp. the lower half of the housing along the axial direction of the turbomachine in two or more housing sections are further divided.

The object of the invention is therefore to provide a housing arrangement of the type mentioned, in which the leaks of screwed together housing components should be avoided while relieving the screw to keep the load occurring during a cold start as low as possible. Furthermore, as far as possible no fatigue cracks should arise in the housing arrangement.

To solve the problem, an initially mentioned housing arrangement is proposed in which the radial clearance of at least one screw is filled with a thermally conductive filler. Preferably, the filler couples the cylindrical surface of the clamping bolt and the surface of this opposite side wall of the receptacle particularly thermally efficient. Overall, the invention is based on the recognition that the clamping bolt heats up comparatively late, compared to the housing and its flanges. As a result, the already pre-stretched clamping bolt stretched in the relatively cold state, which previously adjusted the plastic deformation. According to the invention, this time delay should be minimized. For this purpose, it is proposed that the clamping bolt is thermally coupled to the flange by a fill-filling the filler, which is particularly thermally conductive, establishes a further contact between the clamping bolt and recording in the recording. As a result, a thermal bridge can thus be provided, which leads to a significantly faster heating of the clamping bolt during cold start of the turbomachine. The heat flow is no longer done only via the thread of the nuts in the clamping bolt, but also on the housing flange and filler. Consequently, the clamping bolt expands as fast as the flanges, which can prevent plastic deformation of the clamping bolt. Accordingly, the initial introduced bias voltage can be maintained. Bias losses can thus be avoided both during initial operation of the turbomachine and in recurring operation.

Due to the avoidance of the bias losses of the clamping bolt and leaks between the two flange-adjacent housing components can be further avoided. This tends to increase the performance of the turbo machine as well as less demanding auxiliary system components since their thermal load also decreases with decreasing leakage.

Advantageous embodiments are specified in the subclaims.

Conveniently, the filler may be a solid material, a paste or a liquid. As a solid material, for example, metallic moldings, metal wool, or a metallic granules in question. As a paste, for example, thermal paste could be used. However, it is important to ensure that the eligible Materials are temperature resistant, ie can withstand the maximum occurring during operation in the flange connection temperatures. The heat-conducting filling can also be provided in the form of preformed half shells made of metal wool, wherein two half shells can engage around a clamping bolt. The dimensions of, for example, half shells are chosen so that a simple assembly is ensured while intimate connection of clamping bolt and wall of the recordings. For example, the inner diameter of the half-shell can be chosen so that it can snugly fit snugly on the cylindrical portion of the clamping bolt. The outer diameter of the half-shell may be slightly larger than the diameter of the receptacle in which the clamping bolt is seated. By the aforementioned construction, the radial clearance between the clamping bolt and its receptacle to achieve the aforementioned advantages can be completely filled with a thermally conductive filler.

Particularly advantageous is the embodiment in which the bracing of the screw, the filler is compressible, spreadable and / or deformable. For example, the length of the half-shells may be dimensioned somewhat larger than the clearance to be filled. The dimensions of the half-shells in the radial direction can then be slightly smaller than the dimensions of the clearance in the same direction. In order to compress or deform the filler while bringing into intimate contact with the clamping bolt and the side wall of the receptacles, the clamping bolt can be encompassed in the receiving area of two annular pressure rings, between which the filler is provided. The two pressure rings are applied to the nuts or to the washers and are moved simultaneously with these when screwing the nuts together, whereby a compression resp. Deformation of the filler can be achieved, which causes a thickening of the filler across it. Alternatively, it is conceivable that in addition pressure sleeves between the pressure rings and the washers are provided. Since the two pressure rings are moved toward each other during clamping of the clamping bolt, the optionally elastic filler can due to the forced transverse thickening of all surrounding him areas very large area and intimate, creating a particularly efficient thermal coupling of the flange can be achieved with the clamping bolt ,
Consequently, with a proposed construction, a particularly service- and installation-friendly invention can be specified, since in the cold, stress-free state, all components involved in the fitting can be positioned without further aids.

Overall, by providing the thermal bridge in the region of the receptacle, the heat conduction can be achieved to a similar extent as in the flange, so that the known from the prior art disadvantages, if at all, set only to a reduced extent. The plastic deformation of the clamping bolt can be avoided due to the relatively rapid heating and thus timely induced thermal expansion. At the same time the intermediate inclination of the bearing surfaces for the nut with the resulting bending stress of the clamping bolt is significantly reduced. This also reduces the amount of overstretch and the amount of bias loss. The tightness of the Teilfugenflansches or the flange can be significantly improved overall.

Conveniently, the receptacles are formed as arranged in flanges holes. Consequently, the area of the receptacles in which the thermal bridge can be provided is around the cylindrical sidewalls of the preferably drilled holes.

In an advantageous manner, each housing component has, for each screw connection, in each case a receptacle lying opposite one another, through which the associated clamping bolt extends. Then both housing components can be clamped together by means of two screwed on both sides of the clamping bolt nuts. As a result, both housing components can be pressed under high tension particularly close to each other.

As an alternative to the aforementioned embodiment, it is possible for one of the two housing components to have a thread for each screw connection with clamping bolts directly screwed into it. The other of the two housing halves then has a thread opposite the receptacle for the clamping bolt. For clamping the two housing halves then only one nut is required, which are screwed to the thread opposite the end of the clamping bolt. This space-saving type of unilaterally screwed into the housing clamping bolt is also known as a stud.

Particularly advantageous is the embodiment in which several or each clamping bolt surrounded by a filler sits in its associated receptacles. Thus, each clamping bolt is particularly efficiently coupled to the flange thermally. Conveniently, the clamping bolt is designed as a screw bolt. Equally expedient is the use of the housing arrangement according to the invention in a stationary turbomachine such as a gas turbine or a steam turbine.

FIG 1

einen Ausschnitt durch den Querschnitt einer Gehäuseanordnung mit zwei flanschartig aneinander liegenden und miteinander verspannten Gehäusekomponenten,

FIG 2

einen Ausschnitt durch den Querschnitt einer Gehäuseanordnung mit geringfügig zueinander

FIG 3

versetzten Gehäusekomponenten und die Draufsicht auf den Ausschnitt gemäß FIG 2.

Further advantages and further features of the invention are set forth in a schematic drawing. It shows:

FIG. 1

a detail through the cross section of a housing assembly with two flange-like contiguous and clamped housing components,

FIG. 2

a section through the cross section of a housing assembly with slightly to each other

FIG. 3

offset housing components and the top view of the cutout according to FIG. 2 ,

The FIG. 1 shows the cross section through an assembly 8 of two flange-adjacent housing components 10, 12 of an axially flowed stationary gas turbine. The housing components 10, 12 are an upper housing part and a lower housing part. It could also be two housing sections of the upper part or of the lower part. In the interior 14 of the two housing components 10, 12 comprehensive housing 16 occurs during operation of the gas turbine, a comparatively high pressure at relatively high temperatures, so that the flange-like housing components 10, 12 for sealing their between the adjacent flanges 18, 20 formed Slits are firmly screwed together.

In principle, the housing arrangement 8 has a multiplicity of screw connections 22 in order to achieve the most dense and reliable flange connection possible.

The invention is explained in more detail by way of example on one of the screw connections 22, but it is understood that advantageously each of the two flanges 18, 20 can be configured to press one another screwed connections 22.

The screw 22 comprises a bolt designed as a clamping bolt 24 which extends through both flanges 18, 20 therethrough. For this purpose, the two flanges 18, 20 on opposite receptacles 26, 28, which are designed as substantially aligned holes. In order to press the two flanges 18, 20 along a contact surface 30 with a high biasing force against each other, a nut 32 is screwed onto the clamping bolt 24 on both sides of the clamping bolt 24, so that the Clamping bolt 24 is stressed in the bolted state to tensile stress. The tension is chosen so large that the clamping bolt 24 is stretched to just before its yield point. Between the nuts 32 and the flanges 18, 20, a washer 34 for better distribution of the contact pressure generated by the nuts 32 on the flange is provided in each case. The clamping bolt 24 has in its axial portion which lies within the receptacles 26, 28, a reduced diameter expansion shaft, so that a clearance 36 between its cylindrical surface 38 and a side wall opposite thereto 40 is present. The free space 36 is in cross section - based on the clamping bolt 24 - annularly formed around this.

In the prior art, the heat occurring during operation of the gas turbine from the interior 14 was passed into the clamping bolt 24 via the following path. The housing components 10, 12 warm up during cold start from the inside to the outside, so that the heat conduction reaches the free ends of the flanges 18, 20. Due to the flat contact of the washers 34 on the flanges 18, 20 and the voltage applied to the washers 34 nuts 32, the heat passes through the interlocking thread 33 of nuts 32 and clamping bolt 24 further into this, so that in the receptacles 26, 28th located portion due to the Wärmeleitwiderstandes in terms of time as the last section is heated from both ends ago. In order to keep the delay of the heating of the expansion as low as possible, the invention proposes that the free space 36 resp. Spielraum with a particularly thermally conductive filler 42 is partially or completely filled. The filler 42 couples the cylindrical surface 38 of the clamping bolt 24 to the side wall 40 of the receptacles 26, 28, so that now during the cold start of the gas turbine, a particularly rapid heating of the central portion of the clamping bolt 24 can take place. According to the invention, in particular that portion of the clamping bolt 24, which within the receptacles 26, 28 is now heated much faster compared to a known from the prior art bolted connection. In particular, this makes it possible to avoid plastic deformation of the clamping bolt during a cold start of the gas turbine, so that the applied during assembly of the clamping bolt preload can be permanently obtained.

In order to achieve a particularly compact and large-area connection of the filler 42 to the side wall 40 and to the cylindrical surface 38, the clamping bolt 24 may be encompassed in the region of the receptacles 26, 28 of two annular pressure rings 46, between which the filler 42 is provided. In the preparation of the screwing or screwing the nuts 32 on the clamping bolt 24, the two pressure rings 46 can be moved towards each other by, for example, between the washers 34 and the flanges 18, 20 provided compression sleeves 48, whereby the filler 42 is compressed or deformed is that he particularly intimately to the surfaces 38, 40 nestles. Through the intimate contact of filler 42 and the surfaces 38, 40, the heat transfer resistance between the material of the housing components 10, 12 and the filler 42 and the latter and the clamping bolt 24 can then be advantageously reduced, so that a particularly rapid heating of the clamping bolt 24 in Range of shots 26, 28 is achieved during cold start.

As filler 42, for example, steel wool, copper wool or metallic granules can be used. Depending on the design of the housing assembly 8 but it is also possible to use a paste or liquid as a filler.

The filler 42 can be introduced as a preformed element in the game room. For example, the preformed element may be formed in two parts and half-shell-shaped, and this may be provided with a slight excess.

In FIG. 2 is a similar clipping too FIG. 1 shown, however, the two holes 26, 28 in which the clamping bolt 24 is seated, manufacturing and / or tolerances not completely aligned. In order nevertheless to achieve an intimate heat coupling, a total of four metallic rings 50, 52, 54, 56 are provided, of which two as ring pair 51, 55, the thermal connection of the expansion of the upper and lower housing components 10, 12 are intended. Each ring pair 51, 55 comprises an outer ring 50, 54, which each have an outer, cylindrical lateral surface 58 and an inner, conical inner surface 60. The respective second ring 52, 56 of each ring pair 51, 55 is in the outer ring 50, respectively. 54, and each has an outer, conical lateral surface 62 and an inner, cylindrical inner surface 64. The two rings 50, 52 resp. 54, 56 of each pair 51, resp. 55 are arranged so that the outer cone 62 of the inner ring 52, 56 abuts against the inner cone 60 of the outer ring 50, 54. The inclination of the cones is chosen so that when tightening the screw a - viewed in the axial direction of the clamping bolt 24 directed - force on the rings 50, 52, 54, 56 exercise, so that they are pressed into each other. Due to the conical contact surface resulting from a radially directed force, which is for a particularly intimate contact of clamping bolt 24 to the inner rings 52, 56, of inner rings 52, 56 to the outer rings 50, 54 and outer rings 50, 54 at the side walls 40 of the receptacles 26, 28 ensures, so that a particularly efficient thermal bridge can be achieved. Another advantage is the use of spring elements, such as coil springs 66, between the rings 50, 52 respectively. 54, 56 and the printing sleeves.

How on FIG. 3 It can be clearly seen that the inner cylindrical inner surface 64 of the inner rings 52, 56 and / or the inner conical inner surface 60 of the outer rings 50, 54 eccentrically, that is eccentrically arranged so that in particular in non-aligned receptacles 26, 28 respectively a particularly large area connection between touching parts can be reached. In order to achieve a simple assembly, the rings 50, 52, 54, 56 may each be formed from two ring halves, as this FIG. 3 shows.

Of course, the in FIG. 2 and FIG. 3 shown embodiment are also applied in the use of a directly screwed into the housing component 10 or 12 stud bolts. It goes without saying that due to the presence of only one recording 26 resp. 28 then only a ring pair 51, respectively. 55 is necessary. Also in FIG. 1 illustrated embodiment of a thermal bridge can be designed as a stud execution.

Due to the improved flange connection of the housing components 10, 12, the leakage flow along a contact surface 30 can be prevented or reduced. This tends to result in a higher overall efficiency of the gas turbine. At the same time a reduced technical complexity for the high temperature resistant auxiliary system components can be achieved. This results in a reduced technical complexity for their construction. Also can be specified by the invention, a more reliable housing connection. In principle, a smaller diameter of the clamping bolt 24 is possible by the use according to the invention or less expensive materials can also be used.

Overall, with the present housing assembly 8, a significantly improved flange connection is indicated, in which the otherwise highly stressed clamping bolts 24 have improved material utilization while at the same time improving the sealing of the flange connection. In order to achieve this, the housing assembly 8 of a stationary turbomachine is bolted to clamping bolts 24 extending through bores or receptacles 26, 28. The radial clearance 36 or clearance 36 between the clamping bolt 24 and the bore is at least in a screw with a thermally conductive Filler 42 at least partially filled to achieve a thermal bridge between that portion of the clamping bolt 24 and the flanges 18, 20, which lies within the holes.

Claims (15)

Housing arrangement (8) for a stationary turbomachine, with two housing components (10, 12) screwed together in a flange fashion, of which at least one of the two housing components (12) is screwed together for each of the two housing components (10, 12) ) has a receptacle (26, 28), wherein each screw (22) comprises a through the receptacle (26, 28) extending clamping bolt (24) which sits with a clearance (36) in the receptacle (26, 28),
characterized in that the clearance (36) at least one screw (22) with a thermally conductive filler (42) is at least partially filled. The housing assembly (8) of claim 1, wherein the filler (42) thermally couples the cylindrical surface (38) of the tension bolt (24) and the side wall (40) of the seat (26,28) opposite that surface (38). A housing assembly (8) according to claim 1 or 2, wherein the filler (42) is a solid material, a paste or a liquid. A housing assembly (8) according to claim 1, 2 or 3, wherein the filler (42) is metal wool, steel wool, copper wool or metallic granules. Housing arrangement (8) according to one of claims 1 to 4, wherein when clamping the screw (22) of the filler (42) is compressible, spreadable or deformable. Housing assembly (8) according to any one of claims 1 to 5, wherein the filler (42) is formed as a preformed element, which is one or more parts with slight oversize or undersize in the receptacles (26, 28) is inserted. Housing arrangement (8) according to one of claims 1 to 6, wherein the clamping bolt (24) in the region of the receptacles (26, 28) by two annular pressure rings (46) is encompassed, between which the filler (42) is provided. Housing arrangement (8) according to one of claims 5 and 7, in which for compression respectively. Deformation of the filler (42) each screw (22) has two on the pressure rings (46) adjacent pressure sleeves (48), the pressure rings (46) moves towards each other during clamping of the screw (22). Housing arrangement (8) according to one of claims 1 to 9, wherein the receptacle (26, 28) as in flanges (18, 20) arranged hole or recess is formed. Housing arrangement (8) according to one of claims 1 to 9, wherein each housing component (10, 12) for each screw (22) each have a respective opposite receptacle (26, 28) through which the clamping bolt (24) extends and in which the housing components (10, 12) by means of two screwed on both sides of the clamping bolt (24) screw nuts (32) are clamped together. Housing assembly (8) according to any one of claims 1 to 9, wherein one of the two housing component (10) for each screw (22) has a thread with screwed therein clamping bolt (24) and the clamping bolt (24) at its end opposite the thread a Nuts (32) for clamping the two housing halves (10, 12) with each other is screwed on. Housing arrangement (8) according to claim 8 and 10, wherein in addition between the pressure ring (46) and nut (32), a spring element is provided. Housing arrangement (8) according to one of claims 1 to 12, with a plurality of clamping bolts (24) which are each at least partially surrounded by the filler (42). Housing arrangement (8) according to one of claims 1 to 13, wherein the clamping bolt (24) is designed as a screw bolt. Stationary turbomachine with a housing arrangement (8) according to one of claims 1 to 12.

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