US20170023000A1

US20170023000A1 - Compact backup seal for a turbomachine housing

Info

Publication number: US20170023000A1
Application number: US14/651,007
Authority: US
Inventors: Jan Weule
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2012-12-17
Filing date: 2013-12-17
Publication date: 2017-01-26

Abstract

A turbomachine, having a housing pot and a housing cover which is arranged on the housing pot forming a common contact surface, and which is in particular, screwed counter to the housing pot forming a common contact surface, and comprising a seal which is arranged in the common contact surface for sealing the common contact surface and which includes a first sealing element and a second sealing element which is arranged radially offset to the first sealing element, is provided. In order to produce a compact and yet pressure-proof housing, the first and the second sealing elements are also arranged axially offset to each other in the common contact surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to PCT Application No. PCT/EP2013/076875, having a filing date of Dec. 17, 2013, based on DE 10 2012 223 462.4 having a filing date of Dec. 17, 2012, the entire contents of which are hereby incorporated by reference.

FIELD OF TECHNOLOGY

The following relates to a housing for a turbomachine, in particular for a compressor, having a housing barrel and a housing cover which is arranged on the housing barrel via a common contact surface, and having, arranged in the common contact surface, a seal for sealing the common contact surface with a first sealing element and a second sealing element that is arranged radially offset with respect to the first sealing element, wherein the first and second sealing elements are also arranged axially offset with respect to one another.

BACKGROUND

Compressors or fluid-compressing devices are used in various areas of industry for various applications involving the compression of fluids, especially (process) gases.
Known examples of this are turbocompressors in mobile industrial applications, such as in exhaust gas turbochargers or in jet engines, but also in static industrial applications such as geared compressors or geared turbocompressors for air fractionation.
DE 23 26 848 A1 discloses a seal arrangement of the type defined in the introduction.
In the case of such a—continuously working—turbocompressor, the pressure increase (compression) in the fluid is brought about by increasing an angular momentum of the fluid from inlet to outlet by means of a rotating rotor of the turbocompressor, this rotor having blades extending radially and this increase being brought about by the rotation of the blades. Here, i.e. in such a compressor stage, the pressure and temperature of the fluid increase while the relative (flow) speed of the fluid in the rotor or turborotor decreases.
In order to achieve a maximum possible pressure increase or compression of the fluid, it is possible for multiple such compressor stages to be connected in series.
The architectures of turbocompressors can be divided into centrifugal compressors and axial-flow compressors.
In the case of an axial-flow compressor, the fluid to be compressed, for example a process gas, flows in a direction parallel to the axis (axial direction) through the compressor. In the case of the centrifugal compressor, the gas flows axially into the rotor of the compressor stage and is then diverted outward (radially, radial direction). In the case of multistage centrifugal compressors, it is thus necessary to redirect the flow after each stage.
Combined architectures of axial-flow and centrifugal compressors draw in, with their axial stages, large volume flows which are compressed to high pressures in the subsequent centrifugal stages.
While use is generally made of single-shaft machines, in the case of (multistage) geared turbocompressors (in the following also just ‘geared compressors’ for short), the individual geared stages are grouped around a large gear, wherein multiple parallel (pinion) shafts, which each bear one or two rotors (turborotors arranged at free shaft ends of the pinion shafts) which are accommodated in pressurized volute housings that are created as housing fixtures and that bring about the incoming and outgoing flow to and from the compressor stages, are driven by a large drive gearwheel—a large gear—mounted in the housing.
In the pressurized volute housing (in a barrel-type embodiment also termed barrel volute housing), i.e. in a cylindrical bore in the volute housing (this part of the (barrel) volute housing is also often termed simply housing barrel or merely barrel), a volute insert is inserted aside from the rotor such that, in the cylindrical bore (of the (housing) barrel), there remains on the axial end face of the volute insert a space enclosed by the volute housing and the volute insert, what is termed an annular space, via which the fluid—coming from the rotor—flows away radially via a widening cross section.
The fluid then flows via plant piping, such as a pressure connector pipe which is arranged on the volute housing or on the (housing) barrel and has a pressure connector flange arranged thereon, from the annular space further out of the compressor stage.
The fluid flows into the volute housing via a barrel volute intake flange formed as an (axial end) housing cover (or also simply termed ‘cover’) which—screwed onto the barrel volute housing or onto the (housing) barrel by means of a (housing) cover screw connection via a common ‘radial’, i.e. extending radially, axial, contact surface (in the following also simply ‘radial’ contact surface for short)—closes the barrel volute housing or the (housing) barrel axially.
Such a geared compressor, a geared compressor manufactured by Siemens with the designation STC-GC and used for air fractionation, is known from http://www.energy.siemens.com/hq/de/verdichtung-expansion-ventilation/turboverdichter/getriebeturboverdichter/stc-gc.htm (retrieved 12.14.2012).
Documents WO 2011/076 704 A1, EP 0 723 143 B1, DE 41 27300 A1 and DE 102009012038 A1 each show generic housings.
In order to prevent/minimize pressure losses in such a barrel volute housing, for example through (leakage) fluid flowing out/escaping via the common radial contact surface between the (housing) cover and the barrel volute housing or the (housing) barrel, or in order to seal the (housing) cover, there is provided in the common radial contact surface a (double) seal or tandem seal formed as a backup seal.
To that end, two circumferential (seal) slots, arranged radially with respect to one another or radially one after the other, are introduced in an axial end side of the (housing) cover—at that point on the end side of the (housing) cover at the common radial contact surface—in particular two concentric circumferential seal slots turned axially into the cover and arranged radially one after the other, into which two sealing elements, for example O-rings and/or cup seals, are inserted.
For the purpose of monitoring the (tandem/backup) seal or for monitoring the sealing action of the radially inner seal/sealing element of the two seals/sealing elements, there is usually provided, between the two sealing elements, what is termed an interspace monitoring arrangement in the cover of the barrel volute housing. That is to say the sealing action of the radially inner sealing element is checked by the interspace monitoring arrangement.
To that end, there is provided a further circumferential (monitoring) slot which is introduced/turned axially in the end side of the cover, radially between the two seal slots, which slot forms an interspace to be monitored in the common radial contact surface between the cover and the barrel, i.e. in the common radial contact surface at that point radially between the two seals/seal slots.
A connection is established ‘out’ from the monitoring space to be monitored via a duct system leading through the cover from an axial bore which opens into the monitoring space, and a radial bore that connects to the axial bore and opens into a (connection) region on an outer circumferential surface of the cover.
At that point where the radial bore in the cover meets the outer circumferential surface of the cover, or rather in the connection region of the outer circumferential surface of the cover, a connection flange is welded or screwed to the cover which in turn is connected to a monitoring device, for example a sensor for the detection of leaks.
This seal or the double/tandem seal of the barrel volute housing leads to a large space requirement which has a disadvantageous effect on the component size of the barrel volute housing and thus also on the component size of the turbomachine. In addition, the (housing) cover screw connection is also far removed from the pressure force acting—from inside the volute housing—on the volute housing, such that the screw connection has to be made accordingly bigger in order to apply a respective necessary screw force.

SUMMARY

Embodiments of the invention relate to indicating a barrel volute housing for a turbomachine which permits a compact and yet pressure-resistant construction of the housing and thus also of the turbomachine.
An aspect relates to a housing for a turbomachine.
The housing of the turbomachine has a housing barrel and a housing cover which is arranged on the housing barrel via a common contact surface, in particular screwed onto the housing barrel via the common contact surface by means of a housing cover screw connection.
The housing of the turbomachine also has, arranged in the common contact surface, a seal for sealing the common contact surface. The seal is arranged as a double/tandem seal equipped with a first sealing element and a second sealing element (double/tandem seal) that is arranged radially offset or radially adjacent with respect to the first sealing element.
It is moreover provided that the first and second sealing elements—aside from or in addition to the radial offset—are also arranged axially offset with respect to one another or axially next to each other in the common contact surface.
In clear and simple terms, it is provided according to embodiments of the invention that the double/tandem seal is arranged with the two sealing elements, which are (otherwise only) arranged radially next to one another, both radially and also axially offset, i.e. ‘diagonally’ or ‘nested’ with respect to one another.
By virtue of embodiments of the invention, or by virtue of its diagonal arrangement/nesting of the sealing elements, it is thus possible for the sealing elements of the seal to be arranged in a (more) compact manner with respect to one another—and thus for a compact and yet pressure-resistant housing of the turbomachine to be produced.
This also makes it possible for the housing cover screw connection to sit closer to the sealing elements and thus also to the pressure surface—and can therefore be made smaller. In addition, this also improves a residual clamping force of the housing cover screw connection.
Embodiments of the invention thereby makes it possible to reduce wall thicknesses of the housing or of the housing barrel, which further leads to smaller components. Embodiments of the invention thus makes the housing more lightweight and more cost-effective.
Preferred developments of embodiments of the invention also emerge from the dependent claims.
According to one preferred embodiment, it is provided that the first sealing element is arranged in a first sealing element receiving portion and the second sealing element is arranged in a second sealing element receiving portion, wherein the first and second sealing element receiving portions are formed in the housing cover and/or in the housing barrel, but in particular in the housing cover.
Particularly preferably, it can in this context further be provided that the first and/or second sealing element receiving portion is formed as a circumferential bevel, in particular on the housing cover.
It can also be provided that the first sealing element receiving portion is formed as a circumferential bevel and the second sealing element receiving portion is formed as a circumferential, rectangular slot or a circumferential, rectangular recess, in particular on the housing cover.
Precisely by forming a sealing element receiving portion as a (triangular) bevel, i.e. in simple terms radially circumferential spaces (sealing element receiving portions) are beveled (also in short, triangular cross section shape of the bevel replaces—in the case of a rectangular slot—rectangular cross section shape of the slot), it is possible for more compact seal arrangements according to embodiments of the invention—and thus more compact and pressure-resistant turbomachine housings or turbomachines—to be produced. The housing cover screw connection can thus sit closer to the sealing elements and to the pressure surface—and can be made even smaller. In addition, the residual clamping force of the housing cover screw connection is further improved. Also, further reduced wall thicknesses of the housing or of the housing barrel are possible.
Moreover, such bevels are easy to produce, for example by chip-removing methods.
Together with the housing cover, it is also possible for a suction flange to be produced for an incident flow of a fluid into the turbomachine housing. Often, also, the housing cover is simply termed a suction flange or a (hat-shaped) barrel volute suction flange.
It can further be provided that the sealing elements are O-rings, cup seals, profile seals or other similar sealing elements, or combinations of these, in particular made of plastic, for example PTFE. O-rings, cup seals, profile seals or similar sealing elements, in particular made of plastic, for example PTFE—in diverse configurations—are amply known and proven in the prior art and are obtainable cost-effectively.
Particularly preferably, it can also be provided that the first sealing element is arranged radially outside the second sealing element and the first sealing element is an O-ring and the second sealing element is a cup seal.
In simple terms, the radially outer sealing element is an O-ring and the radially inner sealing element is a cup seal.
Particularly preferably, it can in this context further be provided that the cup seal sits in a rectangular slot in the housing cover and the O-ring sits in a bevel in the housing cover.
According to one preferred development, there is provided an interspace monitoring arrangement for the seal, in particular for a monitoring space formed in the common contact surface radially between the first and the second sealing element.
Thus, i.e. by means of this interspace monitoring arrangement (radially between the two sealing elements), it is possible for the sealing action of the radially inner sealing element of the two sealing elements, for example the cup seal, to be checked.
It can particularly preferably be provided that the interspace monitoring arrangement has a circumferential bevel which is formed on the housing barrel and delimits the monitoring space, and which is formed on the housing barrel such that it is arranged in the common contact surface, radially and axially between the first and second sealing elements.
Specifically also by forming the monitoring space by means of a bevel on the housing barrel, i.e. here too the radially circumferential space (monitoring space) is beveled (and it is possible to dispense with a slot for the monitoring space, as well as corresponding slots for the sealing elements), it is possible to produce still more compact monitored seal arrangements according to embodiments of the invention—and thus more compact and pressure-resistant turbomachine housings or turbomachines.
The housing cover screw connection can thus also in this case sit even closer to the sealing elements and to the pressure surface—and can be made even smaller. In addition, the residual clamping force of the housing cover screw connection is further improved in this context. Further reduced wall thicknesses for the housing or for the housing barrel are thus also possible.
Furthermore, it can also preferably be provided that the interspace monitoring arrangement has a bore which opens into the monitoring space in the region of the bevel, wherein the bore is formed perpendicular to the bevel.
This simplifies drilling when producing the ‘monitoring bore’, and—by virtue of a short ‘monitoring bore’ which can be created thereby and a drilling surface for the ‘monitoring bore’ which is at an angle to the sealing surface of the radially inner sealing element—damage to the sealing surface of the radially inner sealing element is substantially excluded.
According to a further preferred development, it is provided that the interspace monitoring arrangement further has a screw connection surface which is formed, in particular milled, on an outer circumferential surface of the housing barrel and which serves for screwing on a connection element for the interspace monitoring arrangement on the housing barrel.
Milled screw-connection surfaces of this type for components screwed on there can be produced simply and reliably, and thus ensure pressure-resistant component connections. Moreover, it is thus possible to avoid welded connections which are unreliable, more prone to defects, (more) difficult to produce and/or more complex.
A sensor system can be connected to the connection element, which sensor system detects leaks entering the interspace to be monitored, and thus checks the sealing action of the radially inner sealing element.
If, as provided by way of development, the interspace monitoring arrangement is thus created on the housing barrel, it is then furthermore possible for disassembly of the housing or of the housing cover to be simplified without dismantling the interspace monitoring arrangement—indeed because it is not necessary to dismantle the latter.
According to one further preferred development, there is provided a volute insert arranged in the housing barrel and having a common radial contact surface with the housing barrel and with the housing cover.
In other, clear and simple terms, this volute insert in the housing barrel is axially lengthened beyond the housing barrel, and thus provides—via its axially lengthened outer circumferential surface—a radial contact surface both with the housing barrel and for the housing cover. An easily-performed centering of the volute insert and of the housing cover (or also a (barrel volute) suction flange created together with the housing cover) is hereby possible.
Particularly preferably, it can in this context further be provided that the radially inner sealing element is arranged on the outer circumferential surface of the volute insert.
That is to say, the radial contact between the volute insert and the housing (housing barrel and housing cover) is used multiple times. In addition to the centering of the volute insert and the housing cover/suction flange, the radial contact also serves as a ‘support’ for the radially inner sealing element.
It is thus possible to reduce the number of fits for the housing, which makes it considerably easier to machine.
It can moreover be preferably provided that the housing is used in a compressor, in particular a compressor for carbon dioxide applications.
In that context, the compressor can be a single-shaft compressor.
The compressor can also be a geared turbocompressor. In other words, in a further preferred development, the housing according to embodiments of the invention is installed in a geared turbocompressor as a receiving portion for a rotor of a compressor stage and as a flow guide for a fluid in the compressor stage.
It can also be provided that the housing is used in an expander or a turbine.
The above description of advantageous refinements of embodiments of the invention contains numerous features which, in some cases, are reproduced in the individual dependent claims, combined with one another. However, a person skilled in the art will also expediently consider these features individually, and combine them to make worthwhile further combinations.

BRIEF DESCRIPTION

Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

FIG. 1 shows a longitudinal section through part of a compressor stage of a geared compressor, having a barrel volute housing with a compact backup seal;

FIG. 2 is a detail representation of FIG. 1, with a detail of the geared compressor having a barrel volute housing with a compact backup seal;

FIG. 3 is a detail representation of FIG. 1, with a detail of the geared compressor having a barrel volute housing with a compact backup seal;

FIG. 4 is a plan view of a geared compressor having a barrel volute housing with a compact backup seal; and

FIG. 5 is a detail representation of FIG. 1, with a detail of the geared compressor having a barrel volute housing with a compact backup seal.

DETAILED DESCRIPTION

FIG. 1 shows a longitudinal section through a represented part of a compressor stage 18 of a geared compressor 10, having a barrel volute housing 1 according to embodiments of the invention which accommodates the compressor stage 18.
The barrel volute housing 1 (in the following just ‘housing 1’) has a housing barrel 2 (in the following just ‘barrel 2’) and a housing cover 8 (in the following just ‘cover 8’ or also just ‘(barrel volute) suction flange 8’) which is screwed against the barrel 2 via a common contact surface 6 (between the barrel 2 and the housing cover 8) by means of a screw connection 19.
The compressor stage 18 is formed by a rotor shaft or pinion shaft (not shown for the sake of clarity) which is accommodated in an axial bore 15 in the barrel 2, and at one end of which there is attached a rotor (also not shown) located in the barrel 2.
(Axially) incident upon the rotor is an axial incident flow 12 of a fluid 11—which enters the barrel 2 via an axial flange 24 formed in the housing cover 8 (for that reason in the following the housing cover 8 is also termed the barrel volute suction flange 8), and the rotor urges the compressed fluid 11 radially outward into an annular space 23 (shown only schematically), wherein the fluid is also compressed.
The annular space 23 extending in the circumferential direction about the axis of rotation 22 is formed by the barrel 2 and by a volute insert 7 inserted into a receiving portion 9 or cylindrical bore 9 of the barrel 2.
The volute insert 7 is, as is shown in FIG. 1, fitted into the barrel 2 such that, on the axial end side of the volute insert 7, there remains an enclosed space which forms the annular space 23.
In order to seal the pressurized housing 1, a compact backup seal 3 is introduced in the common contact surface 6 between the barrel 2 and the cover 8, the sealing of which seal is monitored or checked by means of an interspace monitoring arrangement 13.
In addition to FIG. 1, FIGS. 2 and 3 (and also FIG. 5) show this backup seal 3 in detail with its interspace monitoring arrangement 13.
The backup seal 3 is, as shown in FIGS. 1-3 and 5, configured as a double/tandem seal with a first, radially outer sealing element 4, an O-ring, and a second sealing element 5, a cup seal, which is arranged radially inward of the first sealing element 4.
Both sealing elements/seals 4, 5, i.e. the O-ring and the cup seal, are arranged in corresponding sealing element receiving portions 14 and, respectively, 15 in the cover 8.
The two sealing element receiving portions 14 and 15 are, as also shown in FIGS. 1-3 and 5, introduced into the cover 8 such that the two sealing elements 4 and 5 are arranged offset both radially and axially with respect to one another (i.e. ‘diagonally’ or ‘nested’) in the cover 8 or in the common contact surface 6.
To that end, the cover 8 has—in the region of the common contact surface 6—an axial and radial step 25 or a step 25 forming an axial and a radial offset, on which step there are arranged or introduced two receiving portions/recesses 14, 15, i.e. sealing element receiving portions 14 and 15 for the two sealing elements (O-ring and cup seal) 14 and 15.
The receiving portion for the radially outer O-ring 4 takes the form of a (triangular) bevel 14 (radially outward) on the step 25; the receiving portion for the radially inner cup seal 5 takes the form of a rectangular slot 15 (radially inward) on the step 25.
The step 25, respectively its axial and radial offset in the cover 8, creates the diagonal arrangement or the nesting of the two sealing elements 4 and 5, respectively the O-ring 4 and the cup seal 5, which permits a compact setup of the backup seal 3 and thus of the housing 1 or of the compressor stage 18/of the turbomachine 10.
As further shown in FIGS. 1-3 and 5, the volute insert 7 introduced into the barrel 2 is axially lengthened (axial lengthening 30) such that it thus—by means of its axially lengthened outer circumferential surface 31 resulting from the axial lengthening 30—forms, with both the barrel 2 and with the cover 8, a common radial contact surface 21.
This radial outer circumferential surface 31 of the volute insert 7 serves, as shown in FIGS. 1-3 and 5, also as a support surface for the radially inner sealing element 5 or for the cup seal 5.
That is to say that the radial contact over the common radial contact surface 21 between the volute insert 7 and the housing 1, i.e. between the barrel 2 and the cover 8, is used multiple times. In addition to the centering 33 of the volute insert 7 and the cover 8, the radial contact also serves as a ‘support’ for the radially inner sealing element 5.
This allows the number of fits for the housing 1 to be reduced, which makes it substantially simpler to machine.
The interspace monitoring arrangement 13 provides, as shown in FIGS. 1-3, a monitoring space 26 arranged in the common contact surface 6, radially and axially between the first and the second sealing elements 4, 5.
This—radially circumferential—monitoring space 26 is formed by a bevel 27 on the barrel 2, i.e. at that point in the region of the (complementary) ‘counterstep’ of the barrel 2 to the step 25 on the cover 8.
Two bores 28, 29, i.e. an essentially axial first bore and, connecting thereto, an essentially radial second bore, in the barrel 2 or in its barrel wall 35, connect the interspace 26 to be monitored to the outside, i.e. to outside the housing 1.
The first bore 28, which opens in the region of the (monitoring space) bevel 27 in the monitoring space 26, is then oriented essentially perpendicular to the bevel 27.
In that context, drilling when producing the bore 28 is simplified, and—by virtue of a short bore which can be produced thereby and a drilling surface at an angle to the sealing surface of the radially inner sealing element 5 for the bore 28—damage to the sealing surface of the radially inner sealing element 5 is largely excluded.
The second bore 29 runs, as shown in FIGS. 1-3, radially outward—inclined at an angle of approximately 45°—in the barrel wall 35, where it meets, in the case of a milled surface 17 (see also FIG. 4), the outer contour of the barrel 2 toward the outside of the barrel 2.
This milled surface 17 on the outer contour of the barrel 2 serves for the screw connection 20 of a connection component (not shown) for the interspace monitoring arrangement 13.
There can be connected, to the connection element, a sensor system which detects leaks entering the interspace 26 to be monitored—and thus checks the sealing action of the radially inner sealing element 5 or of the cup seal 5.
As FIG. 5 also shows, an assembly securing means 32 for securing the volute insert 7 in the barrel 2 takes the form of a stud bolt (not shown). To that end, a corresponding tapped bore 32 is provided in the volute insert 7, as is a corresponding bore 32 in the barrel 2. The securing takes place when the cover 8 or the suction flange 8 presses the volute insert 7 into the barrel 2.
This backup seal 3, with its two diagonally positioned sealing elements 4, 5, and the beveled (14, 27) radially circumferential spaces in the case of the backup seal 3 and in the case of the interspace monitoring arrangement 13 thus permit a compact, simple-to-produce and pressure-resistant housing 1 in which the wall thicknesses 35 are reduced and also the housing cover screw connection 19 sits closer to the sealing elements 4, 5 and thus also closer to the pressure surface—and can thus also be made smaller. In addition, this also improves the residual clamping force of the housing cover screw connection 19.
Further, it is hereby also possible to reduce the number of fits in the housing 1 and to make centerings 33 in the barrel 2, the cover 8 and the volute insert 7 simple and efficient as they can be used more than once.
Disassembly of the housing 1 is also simpler as, when disassembling the cover 8/suction flange 8, it is not necessary to also disassemble the interspace monitoring assembly 13.
Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.
The invention relates to a housing for a turbomachine, in particular for a compressor, having a housing barrel and a housing cover which is arranged on the housing barrel via a common contact surface, and having, arranged in the common contact surface, a seal for sealing the common contact surface with a first sealing element and a second sealing element that is arranged radially offset with respect to the first sealing element.
Compressors or fluid-compressing devices are used in various areas of industry for various applications involving the compression of fluids, especially (process) gases.
Known examples of this are turbocompressors in mobile industrial applications, such as in exhaust gas turbochargers or in jet engines, but also in static industrial applications such as geared compressors or geared turbocompressors for air fractionation.
In the case of such a—continuously working—turbocompressor, the pressure increase (compression) in the fluid is brought about by increasing an angular momentum of the fluid from inlet to outlet by means of a rotating rotor of the turbocompressor, this rotor having blades extending radially and this increase being brought about by the rotation of the blades. Here, i.e. in such a compressor stage, the pressure and temperature of the fluid increase while the relative (flow) speed of the fluid in the rotor or turborotor decreases.
In order to achieve a maximum possible pressure increase or compression of the fluid, it is possible for multiple such compressor stages to be connected in series.
The architectures of turbocompressors can be divided into centrifugal compressors and axial-flow compressors.
In the case of an axial-flow compressor, the fluid to be compressed, for example a process gas, flows in a direction parallel to the axis (axial direction) through the compressor. In the case of the centrifugal compressor, the gas flows axially into the rotor of the compressor stage and is then diverted outward (radially, radial direction). In the case of multistage centrifugal compressors, it is thus necessary to redirect the flow after each stage.
Combined architectures of axial-flow and centrifugal compressors draw in, with their axial stages, large volume flows which are compressed to high pressures in the subsequent centrifugal stages.
While use is generally made of single-shaft machines, in the case of (multistage) geared turbocompressors (in the following also just ‘geared compressors’ for short), the individual geared stages are grouped around a large gear, wherein multiple parallel (pinion) shafts, which each bear one or two rotors (turborotors arranged at free shaft ends of the pinion shafts) which are accommodated in pressurized volute housings that are created as housing fixtures and that bring about the incoming and outgoing flow to and from the compressor stages, are driven by a large drive gearwheel—a large gear—mounted in the housing.
In the pressurized volute housing (in a barrel-type embodiment also termed barrel volute housing), i.e. in a cylindrical bore in the volute housing (this part of the (barrel) volute housing is also often termed simply housing barrel or merely barrel), a volute insert is inserted aside from the rotor such that, in the cylindrical bore (of the (housing) barrel), there remains on the axial end face of the volute insert a space enclosed by the volute housing and the volute insert, what is termed an annular space, via which the fluid—coming from the rotor—flows away radially via a widening cross section.
The fluid then flows via plant piping, such as a pressure connector pipe which is arranged on the volute housing or on the (housing) barrel and has a pressure connector flange arranged thereon, from the annular space further out of the compressor stage.
The fluid flows into the volute housing via a barrel volute intake flange formed as an (axial end) housing cover (or also simply termed ‘cover’) which—screwed onto the barrel volute housing or onto the (housing) barrel by means of a (housing) cover screw connection via a common ‘radial’, i.e. extending radially, axial, contact surface (in the following also simply ‘radial’ contact surface for short)—closes the barrel volute housing or the (housing) barrel axially.
Such a geared compressor, a geared compressor manufactured by Siemens with the designation STC-GC and used for air fractionation, is known from http://www.energy.siemens.com/hq/de/verdichtung-expansion-ventilation/turboverdichter/getriebeturboverdichter/stc-gc.htm (retrieved 12.14.2012).
Documents WO 2011/076 704 A1, EP 0 723 143 B1, DE 41 27300 A1 and DE 102009012038 A1 each show generic housings.
In order to prevent/minimize pressure losses in such a barrel volute housing, for example through (leakage) fluid flowing out/escaping via the common radial contact surface between the (housing) cover and the barrel volute housing or the (housing) barrel, or in order to seal the (housing) cover, there is provided in the common radial contact surface a (double) seal or tandem seal formed as a backup seal.
To that end, two circumferential (seal) slots, arranged radially with respect to one another or radially one after the other, are introduced in an axial end side of the (housing) cover—at that point on the end side of the (housing) cover at the common radial contact surface—in particular two concentric circumferential seal slots turned axially into the cover and arranged radially one after the other, into which two sealing elements, for example O-rings and/or cup seals, are inserted.
For the purpose of monitoring the (tandem/backup) seal or for monitoring the sealing action of the radially inner seal/sealing element of the two seals/sealing elements, there is usually provided, between the two sealing elements, what is termed an interspace monitoring arrangement in the cover of the barrel volute housing. That is to say the sealing action of the radially inner sealing element is checked by the interspace monitoring arrangement.
To that end, there is provided a further circumferential (monitoring) slot which is introduced/turned axially in the end side of the cover, radially between the two seal slots, which slot forms an interspace to be monitored in the common radial contact surface between the cover and the barrel, i.e. in the common radial contact surface at that point radially between the two seals/seal slots.
A connection is established ‘out’ from the monitoring space to be monitored via a duct system leading through the cover from an axial bore which opens into the monitoring space, and a radial bore that connects to the axial bore and opens into a (connection) region on an outer circumferential surface of the cover.
At that point where the radial bore in the cover meets the outer circumferential surface of the cover, or rather in the connection region of the outer circumferential surface of the cover, a connection flange is welded or screwed to the cover which in turn is connected to a monitoring device, for example a sensor for the detection of leaks.
This seal or the double/tandem seal of the barrel volute housing leads to a large space requirement which has a disadvantageous effect on the component size of the barrel volute housing and thus also on the component size of the turbomachine. In addition, the (housing) cover screw connection is also far removed from the pressure force acting—from inside the volute housing—on the volute housing, such that the screw connection has to be made accordingly bigger in order to apply a respective necessary screw force.
The invention is based on the object of indicating a barrel volute housing for a turbomachine which permits a compact and yet pressure-resistant construction of the housing and thus also of the turbomachine.
The object is achieved with a housing for a turbomachine having the features according to the respective independent claim.
The housing of the turbomachine has a housing barrel and a housing cover which is arranged on the housing barrel via a common contact surface, in particular screwed onto the housing barrel via the common contact surface by means of a housing cover screw connection.
The housing of the turbomachine also has, arranged in the common contact surface, a seal for sealing the common contact surface. The seal is arranged as a double/tandem seal equipped with a first sealing element and a second sealing element (double/tandem seal) that is arranged radially offset or radially adjacent with respect to the first sealing element.
It is moreover provided that the first and second sealing elements—aside from or in addition to the radial offset—are also arranged axially offset with respect to one another or axially next to each other in the common contact surface.
In clear and simple terms, it is provided according to the invention that the double/tandem seal is arranged with the two sealing elements, which are (otherwise only) arranged radially next to one another, both radially and also axially offset, i.e. ‘diagonally’ or ‘nested’ with respect to one another.
By virtue of the invention, or by virtue of its diagonal arrangement/nesting of the sealing elements, it is thus possible for the sealing elements of the seal to be arranged in a (more) compact manner with respect to one another—and thus for a compact and yet pressure-resistant housing of the turbomachine to be produced.
This also makes it possible for the housing cover screw connection to sit closer to the sealing elements and thus also to the pressure surface—and can therefore be made smaller. In addition, this also improves a residual clamping force of the housing cover screw connection.
The invention thereby makes it possible to reduce wall thicknesses of the housing or of the housing barrel, which further leads to smaller components. The invention thus makes the housing more lightweight and more cost-effective.
Preferred developments of the invention also emerge from the dependent claims.
According to one preferred embodiment, it is provided that the first sealing element is arranged in a first sealing element receiving portion and the second sealing element is arranged in a second sealing element receiving portion, wherein the first and second sealing element receiving portions are formed in the housing cover and/or in the housing barrel, but in particular in the housing cover.
Particularly preferably, it can in this context further be provided that the first and/or second sealing element receiving portion is formed as a circumferential bevel, in particular on the housing cover.
It can also be provided that the first sealing element receiving portion is formed as a circumferential bevel and the second sealing element receiving portion is formed as a circumferential, rectangular slot or a circumferential, rectangular recess, in particular on the housing cover.
Precisely by forming a sealing element receiving portion as a (triangular) bevel, i.e. in simple terms radially circumferential spaces (sealing element receiving portions) are beveled (also in short, triangular cross section shape of the bevel replaces—in the case of a rectangular slot—rectangular cross section shape of the slot), it is possible for more compact seal arrangements according to the invention—and thus more compact and pressure-resistant turbomachine housings or turbomachines—to be produced. The housing cover screw connection can thus sit closer to the sealing elements and to the pressure surface—and can be made even smaller. In addition, the residual clamping force of the housing cover screw connection is further improved. Also, further reduced wall thicknesses of the housing or of the housing barrel are possible.
Moreover, such bevels are easy to produce, for example by chip-removing methods.
Together with the housing cover, it is also possible for a suction flange to be produced for an incident flow of a fluid into the turbomachine housing. Often, also, the housing cover is simply termed a suction flange or a (hat-shaped) barrel volute suction flange.
It can further be provided that the sealing elements are O-rings, cup seals, profile seals or other similar sealing elements, or combinations of these, in particular made of plastic, for example PTFE. O-rings, cup seals, profile seals or similar sealing elements, in particular made of plastic, for example PTFE—in diverse configurations—are amply known and proven in the prior art and are obtainable cost-effectively.
Particularly preferably, it can also be provided that the first sealing element is arranged radially outside the second sealing element and the first sealing element is an O-ring and the second sealing element is a cup seal.
In simple terms, the radially outer sealing element is an O-ring and the radially inner sealing element is a cup seal.
Particularly preferably, it can in this context further be provided that the cup seal sits in a rectangular slot in the housing cover and the O-ring sits in a bevel in the housing cover.
According to one preferred development, there is provided an interspace monitoring arrangement for the seal, in particular for a monitoring space formed in the common contact surface radially between the first and the second sealing element.
Thus, i.e. by means of this interspace monitoring arrangement (radially between the two sealing elements), it is possible for the sealing action of the radially inner sealing element of the two sealing elements, for example the cup seal, to be checked.
It can particularly preferably be provided that the interspace monitoring arrangement has a circumferential bevel which is formed on the housing barrel and delimits the monitoring space, and which is formed on the housing barrel such that it is arranged in the common contact surface, radially and axially between the first and second sealing elements.
Specifically also by forming the monitoring space by means of a bevel on the housing barrel, i.e. here too the radially circumferential space (monitoring space) is beveled (and it is possible to dispense with a slot for the monitoring space, as well as corresponding slots for the sealing elements), it is possible to produce still more compact monitored seal arrangements according to the invention—and thus more compact and pressure-resistant turbomachine housings or turbomachines.
The housing cover screw connection can thus also in this case sit even closer to the sealing elements and to the pressure surface—and can be made even smaller. In addition, the residual clamping force of the housing cover screw connection is further improved in this context. Further reduced wall thicknesses for the housing or for the housing barrel are thus also possible.
Furthermore, it can also preferably be provided that the interspace monitoring arrangement has a bore which opens into the monitoring space in the region of the bevel, wherein the bore is formed perpendicular to the bevel.
This simplifies drilling when producing the ‘monitoring bore’, and—by virtue of a short ‘monitoring bore’ which can be created thereby and a drilling surface for the ‘monitoring bore’ which is at an angle to the sealing surface of the radially inner sealing element—damage to the sealing surface of the radially inner sealing element is substantially excluded.
According to a further preferred development, it is provided that the interspace monitoring arrangement further has a screw connection surface which is formed, in particular milled, on an outer circumferential surface of the housing barrel and which serves for screwing on a connection element for the interspace monitoring arrangement on the housing barrel.
Milled screw-connection surfaces of this type for components screwed on there can be produced simply and reliably, and thus ensure pressure-resistant component connections. Moreover, it is thus possible to avoid welded connections which are unreliable, more prone to defects, (more) difficult to produce and/or more complex.
A sensor system can be connected to the connection element, which sensor system detects leaks entering the interspace to be monitored, and thus checks the sealing action of the radially inner sealing element.
If, as provided by way of development, the interspace monitoring arrangement is thus created on the housing barrel, it is then furthermore possible for disassembly of the housing or of the housing cover to be simplified without dismantling the interspace monitoring arrangement—indeed because it is not necessary to dismantle the latter.
According to one further preferred development, there is provided a volute insert arranged in the housing barrel and having a common radial contact surface with the housing barrel and with the housing cover.
In other, clear and simple terms, this volute insert in the housing barrel is axially lengthened beyond the housing barrel, and thus provides—via its axially lengthened outer circumferential surface—a radial contact surface both with the housing barrel and for the housing cover. An easily-performed centering of the volute insert and of the housing cover (or also a (barrel volute) suction flange created together with the housing cover) is hereby possible.
Particularly preferably, it can in this context further be provided that the radially inner sealing element is arranged on the outer circumferential surface of the volute insert.
That is to say, the radial contact between the volute insert and the housing (housing barrel and housing cover) is used multiple times. In addition to the centering of the volute insert and the housing cover/suction flange, the radial contact also serves as a ‘support’ for the radially inner sealing element.
It is thus possible to reduce the number of fits for the housing, which makes it considerably easier to machine.
It can moreover be preferably provided that the housing is used in a compressor, in particular a compressor for carbon dioxide applications.
In that context, the compressor can be a single-shaft compressor.
The compressor can also be a geared turbocompressor. In other words, in a further preferred development, the housing according to the invention is installed in a geared turbocompressor as a receiving portion for a rotor of a compressor stage and as a flow guide for a fluid in the compressor stage.
It can also be provided that the housing is used in an expander or a turbine.
The above description of advantageous refinements of the invention contains numerous features which, in some cases, are reproduced in the individual dependent claims, combined with one another. However, a person skilled in the art will also expediently consider these features individually, and combine them to make worthwhile further combinations.
The figures shows exemplary embodiments of the invention, which will be explained in more detail below. Identical reference signs in the figures relate to technically identical elements. Arrows clarify directions of movement of objects or elements.
In the figures:
FIG. 1 shows a longitudinal section through part of a compressor stage of a geared compressor, having a barrel volute housing according to the invention with a compact backup seal,
FIG. 2 is a detail representation of FIG. 1, with a detail of the geared compressor having a barrel volute housing according to the invention with a compact backup seal,
FIG. 3 is a detail representation of FIG. 1, with a detail of the geared compressor having a barrel volute housing according to the invention with a compact backup seal,
FIG. 4 is a plan view of a geared compressor having a barrel volute housing according to the invention with a compact backup seal and
FIG. 5 is a detail representation of FIG. 1, with a detail of the geared compressor having a barrel volute housing according to the invention with a compact backup seal.
Compact backup seal for a barrel volute housing of a compressor stage in a geared compressor
FIG. 1 shows a longitudinal section through a represented part of a compressor stage 18 of a geared compressor 10, having a barrel volute housing 1 according to the invention which accommodates the compressor stage 18.
The barrel volute housing 1 (in the following just ‘housing 1’) has a housing barrel 2 (in the following just ‘barrel 2’) and a housing cover 8 (in the following just ‘cover 8’ or also just ‘(barrel volute) suction flange 8’) which is screwed against the barrel 2 via a common contact surface 6 (between the barrel 2 and the housing cover 8) by means of a screw connection 19.
The compressor stage 18 is formed by a rotor shaft or pinion shaft (not shown for the sake of clarity) which is accommodated in an axial bore 15 in the barrel 2, and at one end of which there is attached a rotor (also not shown) located in the barrel 2.
(Axially) incident upon the rotor is an axial incident flow 12 of a fluid 11—which enters the barrel 2 via an axial flange 24 formed in the housing cover 8 (for that reason in the following the housing cover 8 is also termed the barrel volute suction flange 8), and the rotor urges the compressed fluid 11 radially outward into an annular space 23 (shown only schematically), wherein the fluid is also compressed.
The annular space 23 extending in the circumferential direction about the axis of rotation 22 is formed by the barrel 2 and by a volute insert 7 inserted into a receiving portion 9 or cylindrical bore 9 of the barrel 2.
The volute insert 7 is, as is shown in FIG. 1, fitted into the barrel 2 such that, on the axial end side of the volute insert 7, there remains an enclosed space which forms the annular space 23.
In order to seal the pressurized housing 1, a compact backup seal 3 is introduced in the common contact surface 6 between the barrel 2 and the cover 8, the sealing of which seal is monitored or checked by means of an interspace monitoring arrangement 13.
In addition to FIG. 1, FIGS. 2 and 3 (and also FIG. 5) show this backup seal 3 in detail with its interspace monitoring arrangement 13.
The backup seal 3 is, as shown in FIGS. 1-3 and 5, configured as a double/tandem seal with a first, radially outer sealing element 4, an O-ring, and a second sealing element 5, a cup seal, which is arranged radially inward of the first sealing element 4.
Both sealing elements/seals 4, 5, i.e. the O-ring and the cup seal, are arranged in corresponding sealing element receiving portions 14 and, respectively, 15 in the cover 8.
The two sealing element receiving portions 14 and 15 are, as also shown in FIGS. 1-3 and 5, introduced into the cover 8 such that the two sealing elements 4 and 5 are arranged offset both radially and axially with respect to one another (i.e. ‘diagonally’ or ‘nested’) in the cover 8 or in the common contact surface 6.
To that end, the cover 8 has—in the region of the common contact surface 6—an axial and radial step 25 or a step 25 forming an axial and a radial offset, on which step there are arranged or introduced two receiving portions/recesses 14, 15, i.e. sealing element receiving portions 14 and 15 for the two sealing elements (O-ring and cup seal) 14 and 15.
The receiving portion for the radially outer O-ring 4 takes the form of a (triangular) bevel 14 (radially outward) on the step 25; the receiving portion for the radially inner cup seal 5 takes the form of a rectangular slot 15 (radially inward) on the step 25.
The step 25, respectively its axial and radial offset in the cover 8, creates the diagonal arrangement or the nesting of the two sealing elements 4 and 5, respectively the O-ring 4 and the cup seal 5, which permits a compact setup of the backup seal 3 and thus of the housing 1 or of the compressor stage 18/of the turbomachine 10.
As further shown in FIGS. 1-3 and 5, the volute insert 7 introduced into the barrel 2 is axially lengthened (axial lengthening 30) such that it thus—by means of its axially lengthened outer circumferential surface 31 resulting from the axial lengthening 30—forms, with both the barrel 2 and with the cover 8, a common radial contact surface 21.
This radial outer circumferential surface 31 of the volute insert 7 serves, as shown in FIGS. 1-3 and 5, also as a support surface for the radially inner sealing element 5 or for the cup seal 5.
That is to say that the radial contact over the common radial contact surface 21 between the volute insert 7 and the housing 1, i.e. between the barrel 2 and the cover 8, is used multiple times. In addition to the centering 33 of the volute insert 7 and the cover 8, the radial contact also serves as a ‘support’ for the radially inner sealing element 5.
This allows the number of fits for the housing 1 to be reduced, which makes it substantially simpler to machine.
The interspace monitoring arrangement 13 provides, as shown in FIGS. 1-3, a monitoring space 26 arranged in the common contact surface 6, radially and axially between the first and the second sealing elements 4, 5.
This—radially circumferential—monitoring space 26 is formed by a bevel 27 on the barrel 2, i.e. at that point in the region of the (complementary) ‘counterstep’ of the barrel 2 to the step 25 on the cover 8.
Two bores 28, 29, i.e. an essentially axial first bore and, connecting thereto, an essentially radial second bore, in the barrel 2 or in its barrel wall 35, connect the interspace 26 to be monitored to the outside, i.e. to outside the housing 1.
The first bore 28, which opens in the region of the (monitoring space) bevel 27 in the monitoring space 26, is then oriented essentially perpendicular to the bevel 27.
In that context, drilling when producing the bore 28 is simplified, and—by virtue of a short bore which can be produced thereby and a drilling surface at an angle to the sealing surface of the radially inner sealing element 5 for the bore 28—damage to the sealing surface of the radially inner sealing element 5 is largely excluded.
The second bore 29 runs, as shown in FIGS. 1-3, radially outward—inclined at an angle of approximately 45°—in the barrel wall 35, where it meets, in the case of a milled surface 17 (see also FIG. 4), the outer contour of the barrel 2 toward the outside of the barrel 2.
This milled surface 17 on the outer contour of the barrel 2 serves for the screw connection 20 of a connection component (not shown) for the interspace monitoring arrangement 13.
There can be connected, to the connection element, a sensor system which detects leaks entering the interspace 26 to be monitored—and thus checks the sealing action of the radially inner sealing element 5 or of the cup seal 5.
As FIG. 5 also shows, an assembly securing means 32 for securing the volute insert 7 in the barrel 2 takes the form of a stud bolt (not shown). To that end, a corresponding tapped bore 32 is provided in the volute insert 7, as is a corresponding bore 32 in the barrel 2. The securing takes place when the cover 8 or the suction flange 8 presses the volute insert 7 into the barrel 2.
This backup seal 3, with its two diagonally positioned sealing elements 4, 5, and the beveled (14, 27) radially circumferential spaces in the case of the backup seal 3 and in the case of the interspace monitoring arrangement 13 thus permit a compact, simple-to-produce and pressure-resistant housing 1 in which the wall thicknesses 35 are reduced and also the housing cover screw connection 19 sits closer to the sealing elements 4, 5 and thus also closer to the pressure surface—and can thus also be made smaller. In addition, this also improves the residual clamping force of the housing cover screw connection 19.
Further, it is hereby also possible to reduce the number of fits in the housing 1 and to make centerings 33 in the barrel 2, the cover 8 and the volute insert 7 simple and efficient as they can be used more than once.
Disassembly of the housing 1 is also simpler as, when disassembling the cover 8/suction flange 8, it is not necessary to also disassemble the interspace monitoring assembly 13.
Although the invention has been illustrated and described in detail by means of the preferred exemplary embodiments, the invention is not limited by the disclosed examples and other variations may be derived herefrom by a person skilled in the art without departing from the scope of protection of the invention.

Claims

1-12. (canceled)

13. A housing for a turbomachine comprising:

a housing barrel and a housing cover which is arranged on the housing barrel via a common contact surface; and

a seal, arranged in the common contact surface, for sealing the common contact surface with a first sealing element and a second sealing element that is arranged radially offset with respect to the first sealing element, wherein the first sealing element and the second sealing element are also arranged axially offset with respect to one another;

wherein the housing has an interspace monitoring arrangement which monitors, for the seal, a monitoring space formed in the common contact surface radially between the first sealing element and the second sealing element.

14. The housing as claimed in claim 13, wherein the first sealing element is arranged in a first sealing element receiving portion and the second sealing element is arranged in a second sealing element receiving portion, wherein the first sealing element and the second sealing element receiving portions are formed in the housing cover.

15. The housing as claimed in claim 14, wherein the first sealing element and/or the second sealing element receiving portion is formed as a circumferential bevel on the housing cover, or that the first sealing element receiving portion is formed as a circumferential bevel and the second sealing element receiving portion is formed as a circumferential, rectangular slot or a circumferential, rectangular recess on the housing cover.

16. The housing as claimed in 13, wherein the first sealing element and the second sealing element are O-rings and/or cup seals.

17. The housing as claimed in claim 13, wherein the first sealing element is arranged radially outside the second sealing element and the first sealing element is an O-ring and the second sealing element is a cup seal or a profile seal.

18. The housing as claimed in claim 13, wherein the interspace monitoring arrangement has a circumferential bevel which is formed on the housing barrel and delimits the monitoring space, and which is formed on the housing barrel such that it is arranged in the common contact surface, radially and axially between the first sealing element and the second sealing element.

19. The housing as claimed in claim 18, wherein the interspace monitoring arrangement has a bore which opens into the monitoring space in a region of the bevel, wherein the bore is formed perpendicular to the bevel.

20. The housing as claimed in claim 13, wherein the interspace monitoring arrangement has a screw connection surface which is formed, on an outer circumferential surface of the housing barrel and which serves for screwing on a connection element for the interspace monitoring arrangement on the housing barrel.

21. The housing as claimed in claim 13, further comprising a volute insert arranged in the housing barrel and having a common radial contact surface with the housing barrel and with the housing cover.

22. The housing as claimed in claim 21, wherein one of the two sealing elements, in particular the radially inner sealing element of the two sealing elements, is arranged on an outer circumferential surface of the volute insert.

23. The housing as claimed in claim 13, used in a compressor, in particular a single-shaft or geared turbocompressor, further in particular for a carbon dioxide application, an expander or a turbine.

24. The housing as claimed in claim 13, wherein the housing cover is screwed onto the housing barrel via the common contact surface.

25. The housing as claimed in claim 20, wherein the screw connection surface is milled on the outer circumferential surface of the housing barrel.