DE102011005105B4 - Outlet collecting housing for a centrifugal compressor - Google Patents

Abstract

The invention relates to a housing assembly for a radial compressor and a method for flow guidance of a flow medium in a centrifugal compressor.
This housing arrangement for the centrifugal compressor has a first, substantially radially oriented, annular cavity and a second, substantially axially aligned, annular cavity, which are connected to one another via a deflection arrangement. In the second, substantially axially aligned, annular cavity, a guide grid is arranged.
In the method for guiding the flow of a flow medium in a radial compressor, the flow medium is guided to the outside substantially in a radial direction. Subsequently, the flow medium is deflected substantially in an axial direction and continued substantially in the axial direction. Upon further flow of the flow medium in the substantially axial direction of the flow, a swirl is at least partially removed.

Description

The invention relates to a housing assembly for a radial compressor and a method for flow guidance of a flow medium in a centrifugal compressor.

Radial compressors are known, for example from the EP 1 356 168 B1 ,

Such centrifugal compressors consist of a compressor stage forming, rotating about a rotational axis impeller with a - with respect to the axis of rotation of the impeller - axial inlet and a radial outlet. Gas to be compressed flows axially into the impeller of the compressor stage and is then deflected outwards (radially or in the radial direction), emerging from the impeller at high speed and with swirling.

Kinetic energy of the high velocity and radially outgoing gas to be compressed is then (beneficially) converted into potential energy in the form of pressure in a diffuser.

Such a diffuser is usually formed by two non-rotating, an annular cavity or an annular space forming rings, which annular space radially adjoins the impeller outlet or which rings or annular walls / side surface radially adjoin the impeller outlet and usually perpendicular to Rotary axis of the impeller or stand at a very obtuse angle to this.

The gas emerging from the impeller is guided radially outward in this annular space between these two annular walls and reaches a collector and / or a spiral via which the compressed gas is collected and discharged from the centrifugal compressor.

Such a spiral, also called a spiral casing, continuously receives the gas to be discharged through a cross-section growing over a circumference of the spiral and leads it into an outlet connection, which is usually followed by a piping system for the forwarding or discharging of the compressed gas.

Due to the over the circumference growing cross-section in the spiral, the gas flowing through it is continuously collected. In the adjoining (conical) outlet diffuser, the flow is further retarded and thus part of its kinetic energy is converted into potential energy, ie. H. in pressure, converted (pressure gain or pressure recovery).

To further achieve the highest possible pressure increase or compression of the fluid, a plurality of such compressor stages can be connected in series, wherein for collecting and discharging the compressed gas from the last compressor stage or from a compressor stage to the next compressor stage also such a spiral is used as described.

While usually single-shaft machines are used, in (multi-stage) Getriebeturboverdichtern (shortly below only gear compressor), the individual compressor stages are grouped around a large wheel, with several parallel (pinion) shafts, each one or two - in such as housing attachments realized spiral housings recorded - run wheels (arranged at free shaft ends of the pinion shafts turbocharger wheels), are driven by a large, mounted in the housing drive gear, a large wheel.

Such a transmission compressor, a transmission compressor from Siemens called STC-GC, used for air separation, is out
http://www.energy.siemens.com/hq/en/compression-expansion-ventilation/turbo-compressor/transmission-boosting-coilers/stc-gc.htm (available on 18.02.2011).

However, such spirals or spiral housings used for the flow guidance and pressure recovery in single-stage or multistage centrifugal compressors have the disadvantage that they are technically complicated to manufacture.

Furthermore, so-called guide grids are known. Under Leitgitter be used in turbomachines, fixed grids understood profiled blades that either swirl a medium flowing in the turbomachine and thereby reduce a pressure (eg turbines) or withdraw the fluid flow a swirl and thereby increase pressure (pressure recovery ) (eg compressor).

From the DE 36 12 412 A1 , of the US 5 722 813 A and the DE 42 19 249 C2 Further different embodiments of radial compressors with housings are known.

The centrifugal compressor from the DE 36 12 412 A1 and the US 5 722 813 A each have a housing with a first radially aligned annular cavity and a second axially aligned annular cavity. The first radially directed, annular cavity and the second axially aligned, annular cavity are connected to one another via a deflection arrangement. By doing second, substantially axially aligned, annular cavity is also arranged a guide grid.

The US 5 722 813 A further discloses an annular plenum disposed at an axial outlet of the second axially aligned annular cavity.

The DE 42 19 249 C2 describes in the (radial compressor) volute a radially aligned outlet diffuser / discharge nozzle through which the compressed air coming from the spiral flows radially outward with the centrifugal compressor.

It is the object of the invention to provide an arrangement and a method which enables the highest possible pressure recovery in a centrifugal compressor. Also, the invention should be simple and inexpensive to implement, make optimal use of the available space and be flexibly adaptable to different flows in radial compressors or be used in different flows in centrifugal compressors.

The object is achieved by a housing arrangement for a radial compressor and a method for flow guidance of a flow medium in a centrifugal compressor with the features according to the respective independent claim.

The housing arrangement for the radial compressor has a first, substantially radially aligned, annular cavity and a second, substantially axially aligned, annular cavity, which are connected to one another via a deflection arrangement. In the second, substantially axially aligned, annular cavity, a guide grid is arranged.

In the method for guiding the flow of a flow medium in a radial compressor, the flow medium is guided to the outside substantially in a radial direction. Subsequently, the flow medium is deflected substantially in an axial direction and continued in the substantially axial direction. In this continuation or further flow of the flow medium in the substantially axial direction of the flow, a swirl is at least partially removed.

This kinetic energy withdrawn from the flow medium is converted into potential energy in the form of pressure, i. H. a (desired) pressure increase of the flow medium, converted. Therefore, it is desirable to withdraw the flow of all possible twist. D. h., According to the flow guide, the flow medium, for example, a process gas to be swirl-free.

The terms "radial" and "axial" are to be understood according to the invention with respect to an axis of rotation of an impeller of the radial compressor or the radial compressor stage. The term "substantially" is to be expressed according to the invention that the direction thus designated permits deviations, which may be in the range of up to 45 °.

Furthermore, according to the invention, the term "aligned" - used for example for the radially oriented, annular cavity or the axially aligned, annular cavity - in the sense of a flow direction, for example, defined by the cavity or realized flow direction of the flow medium to understand.

Thus, under the radial orientation of the radially aligned cavity means that this cavity is formed such, for example, over a substantially larger compared to its axial extent radial extent that forms a radial flow of the flow medium in this cavity or that this cavity through the Flow medium is flowed through radially. Accordingly, under the axial orientation of the axially aligned cavity means that this cavity is formed such, for example, over a much larger compared to its radial extent axial extent that forms an axial flow of the flow medium in this cavity or that this cavity through the Flow medium is flowed through axially.

The housing arrangement according to the invention and its developments are particularly suitable for the method according to the invention.

In this case, flows through the flow medium, usually a process gas, the first, substantially radially oriented annular cavity radially outward, is deflected by the deflection in the substantially axial direction and flows through the second, substantially axially aligned, annular cavity in the substantially axial direction , When flowing through this second cavity of the flow using the guide grid, a twist at least in part, if possible, largely to approximately completely, preferably completely removed.

The invention thus uses a (downstream) guide grille known, for example, from a recirculation stage in a multi-stage turbomachine, such as a multistage radial compressor. The Nachleitgitter or its profiling (blading) in this case causes the flow medium of the impeller of the centrifugal compressor impressed Swirl is removed and converted into pressure (conversion of kinetic into potential energy).

In this case, however, in the invention, the Nachleitgitter not - as in the known feedback stage - centripetally flows through, but according to the invention in the axial direction.

This proves to be particularly advantageous in the invention that can be deviated from the use of known, in structural conditions, such as space limitations, difficult to realize spirals or volute casings for flow guidance and pressure recovery - without having to do without a pressure recovery. Instead, the invention allows by their flow guidance or their structural design with pressure recovery in a limited space this efficiently using solution.

The invention also makes possible a considerably controlled treatment or guidance of the flow through its, compared to a spiral flow guide, simpler flow guidance of the flow medium.

Furthermore, the guide grid according to the invention of the swirl-affected flow can withdraw the swirl and implement this in an increase in pressure (pressure recovery), which is not able to a spiral or a volute casing. There remains the swirl - unused for pressure recovery - in the flow.

Furthermore, it proves to be advantageous in the invention that they provide a flexible adaptation of a radial compressor to different design cases, d. H. different volume flows in the flow medium allows. Thus, an adaptation to a specific volume flow of the flow medium can be carried out solely by means of an adaptation of the guide grid that is easy to implement. The housing of the centrifugal compressor itself can remain unchanged in each case for a machine size.

For example, over a leading edge angle of a profile used in the guide grid, this can be adapted to the flow or the flow over a channel height or over a height of the second cavity to the leading edge angle.

Also, the invention, in particular in combination with a collecting housing, a structurally advantageous and simpler as well as more economical solution for collecting and discharging a flow medium from a radial compressor with pressure recovery as a spiral or as a spiral housing. Thus, a frequently cast version of the spiral requires long delivery times. In addition, high flow losses occur in a welded spiral, which can be reduced by the simple flow guidance in the invention.

Preferred developments of the invention will become apparent from the dependent claims.

In a preferred embodiment, a radial outlet of an impeller of the radial compressor or of a compressor stage of the radial compressor is connected to a radial inlet of the first, substantially radially oriented, annular cavity. Thus, the accelerated and swirling flow - coming from the impeller - can be discharged radially outward.

In this first, substantially radially aligned, annular cavity, in short, only annular space or diffuser, the accelerated by the impeller flow medium, for example, a process gas having a high kinetic energy, slowed due to a radially expanding cross-section of the diffuser and the kinetic energy of the flow medium is converted into pressure.

For this purpose, it can further be provided that this annulus has an optionally adjustable blading through which the pressure recovery can be increased.

In a further preferred embodiment, it is provided that an, in particular annular, collecting space, in particular with a constant over a circumference of the annular collecting space cross section is arranged at an axial outlet of the second, substantially axially aligned, annular cavity (concentric arrangement). Also, a collecting space with over the circumference changing cross sections is possible (eccentric arrangement). The swirl-free or nearly swirl-free flow coming from the secondary lattice is absorbed in the collecting chamber.

Furthermore, the invention provides that at a predetermined circumferential position of the collecting space an outlet diffuser (discharge nozzle), in particular a substantially radially aligned outlet diffuser, is connected to the collecting space. Preferably, the outlet diffuser is conical.

It is also provided according to the invention that a barrier rib is arranged at a predetermined circumferential position of the collecting space, which divides a flow entering into the collecting space into two approximately equal flows.

In a further preferred development of this outlet diffuser, in particular using an outlet flange, connected to a piping system, whereby the compressed flow medium from the centrifugal compressor off and can be forwarded. In this case, the flow medium usually has a predetermined or desired pressure, for example 6 to 8 bar. It is also provided that the flow medium with a predetermined flow rate from the centrifugal compressor off or enters the piping system. This specification of a flow velocity can be based on structural boundary conditions, such as load limits in the pipeline system.

An adaptation of the flow guidance to different volume flows in the flow medium is preferably provided by using or via the (after-) guide grid.

Thus, it can be provided here preferably that a profile of the guide grid or a Leitgitterbeschaufelung is adapted over a leading edge angle of the profile to a flow of a flow medium in the second, substantially axially aligned annular cavity and / or that the flow over a cross section or a (channel) height of the second, substantially axially aligned, annular cavity is adapted to the leading edge angle of the profile of the guide grid.

Preferably, the housing assembly can be used in a single or multi-stage radial compressor. Such a multi-stage centrifugal compressor can also be realized as a transmission compressor.

Although the housing is described in relation to a radial compressor, the invention can be used everywhere in turbomachines where a flow medium is to be led radially out of or into a turbomachine. For example, in radial turbines, where the flow direction of the flow medium is then adjusted accordingly. D. h., The flow medium flows through there first the second cavity, is then deflected in the radial direction and flows through the first cavity radially inwardly.

In figures, embodiments of the invention are shown, which are explained in more detail below.

Show it

1 Sketch in section of a radial compressor;

2 Sketch in a sectional view through an outlet collecting housing of a centrifugal compressor according to an embodiment;

3 Sketch in section through the outlet header of the centrifugal compressor after 2 ;

4 Sketch in section through an outlet collecting housing of a centrifugal compressor according to another embodiment;

5 Sketch in section through an outlet collecting housing of a centrifugal compressor according to another embodiment;

6 Sketch in a sectional view through an outlet collecting housing of a centrifugal compressor according to another embodiment.

Embodiments: Radial compressor and outlet header of radial compressors

1 shows a centrifugal compressor 100 , its outlet header 1 according to one embodiment in the 2 and 3 is shown in more detail.

This radial compressor 100 , as in 1 shown, has an impeller 10 up, about an axis 11 rotated at high speed. The impeller 10 owns a hub 12 and radially projecting blades 13 ,

That - with flow direction 101 - axially incoming gas is through the impeller 10 set in rotation and leaves the impeller 10 in the radial flow direction 101 to the axis 11 and at an obtuse angle to the axis 11 at high speed and with a twist.

The shovels 13 are on a common back plate 14 the hub 12 attached. The impeller 10 is located in a housing 15 whose wall 16 the outer contour of the impeller 10 is adjusted. That of the impeller 10 formed blower has an axial inlet 17 and one around the circumference of the impeller 10 extending radial outlet 18 on. The impeller 10 can also be provided with a final cover plate (not shown) on the outer contour.

At the outlet 18 joins how the next 2 and 3 show an annulus 2 or diffuser 2 on, with the case 15 firmly connected and not rotated.

The annulus or diffuser 2 has a substantially radial support wall 21 on, on the wings 22 (Diffuser paddle) as shown which are the outlet 18 direct passing flow.

The radial support wall 21 of the annulus or diffuser 2 axially spaced apart there is another substantially radial wall 23 , whereby the annulus or the diffuser 2 an annular, occasionally with the blading 22 occupied, radially aligned cavity or channel forms. The wings 22 are substantially radial to the axis 11 ,

The task of the diffuser 2 is that of the impeller 10 accelerated gas, which has a high kinetic energy, and to convert the kinetic energy into pressure. Here, a substantial conversion of the existing swirl into pressure energy only takes place when the diffuser is bladed.

As the 2 and 3 show the compressed gas after flowing through the bladed annulus or diffuser 2 first by means of a bow 4 deflected by 90 ° in the axial or axial direction.

Subsequently, this is in an axial annular channel 3 further flowing gas through an over a circumference of the axial annular channel 3 distributed, and adapted to a flow angle of the gas, profiled Nachleitgitter 5 the spin almost completely removed and converted into pressure energy (pressure recovery).

The adaptation takes place via a front edge angle 27 one on the radially inner wall 28 of the secondary lattice 5 arranged profile or blade profiles 26 ,

The axial ring channel 3 has an (annular) outlet opening 25 through which the compressed and now spin-free gas in an annular cross-section 6 , a collection room 6 , entry.

In the collection room 6 the now swirl-free flow is absorbed and further radially outward into the discharge nozzle or conical outlet diffuser 7 guided.

About the outlet diffuser 7 the gas will continue through an outlet flange 8th (not shown) in a piping system 9 (Not shown) with the desired pressure of, for example, 6 to 8 bar directed at the desired exit velocity. The gas flow is generally further retarded in the outlet diffuser, which results in a further pressure increase in this component.

4 to 6 show further embodiments of the outlet collection housing 1 of the centrifugal compressor 100 , Identical components are denoted the same and, if not explained in more detail above, are designed according to the above.

According to the in 4 illustrated outlet collection housing 1 is the collection room 6 such with the axial annular channel 3 connected to the annular outlet opening 25 at the radially innermost point of the collecting space 6 in the collection room 6 empties. Put simply, the gas or the (twist-free) flow occurs directly at the bottom of the plenum 6 in this one. A further radially inward turn of the flow in the plenum 6 this is not possible. In the collection room 6 the swirl-free flow is absorbed and further radially outward into the discharge nozzle or conical outlet diffuser 7 guided.

An execution after 4 is implemented, if probably still a residual twist after the guide grid 5 is available. Ensures that the swirl through the baffle 5 completely deprived, a more compact design can after 2 be selected, in which the collection space 6 continue to the axis 11 is offset.

5 shows an outlet header 1 in which the collection room 6 the axial ring channel 3 Concentrically "surrounds" over the circumference of the same cross-section. Put simply, in the collection room 6 trained annular channel has constant cross-sections over the circumference. In other words, the collection room 6 is concentric with the axial ring channel 3 arranged (concentric arrangement).

Furthermore, in the outlet header housing 1 to 5 in the collection room 6 a radial barrier rib 24 provided, which, how 5 shows, so in the plenum 6 arranged that for an approximately equal division (about 50% / 50%) of the in the collecting space 6 inflowing swirl-free flow is provided in a right or left flowing or guided gas flow. About the discharge nozzle or the conical outlet diffuser 7 Both currents are discharged radially outward.

According to the in 6 illustrated outlet header 1 is the collection room 6 eccentric to the axial ring channel 3 arranged (eccentric arrangement). This can be easily realized by a jacket plate of the plenum 6 is arranged offset. Here, too, how 6 shows the plenum 6 the barrier rib 24 for dividing the flow into two approximately equal flows.

A special feature of this centrifugal compressor 100 or its housing 1 after the 1 to 6 lies in the use of a known from a feedback stage ago Nachleitgitters, here Nachleitgitter 5 , together with the collection box 6 ,

The tracking grid 5 this causes the flow of the impeller 10 any swirling and swirling of the diffuser blown through, if any, is removed (conversion of kinetic energy into potential energy).

This is the Nachleitgitter 5 but not - as in the known feedback stage - centripetally flows through, but in the axial direction 101 in the axial annular channel 3 ,

The profile used 26 of the secondary lattice 5 can over the leading edge angle 27 to the flow or the flow over the height of the axial annular channel 3 at the leading edge angle 27 be adjusted.

The described flow guide or the described housing 1 represents an advantageous alternative to the use of a spiral, if this is difficult to realize due to structural conditions.

An adaptation to different design cases (different volume flows) in the centrifugal compressor 100 can alone on the adaptation of the secondary lattice 5 be done while the case 1 even for one machine size remains the same.

This and the fact that the Nachleitgitter 5 in combination with the collection housing 6 the structurally simpler (housing) solution relative to the spiral represents the housing described 1 both technically and economically advantageous.

In the following, various alternatives of the described embodiment are mentioned.

Thus, the described flow guide or the housing described 1 also be used in multi-stage centrifugal compressors. There it can - as described above - are used to flow behind the last stage of such a multi-stage centrifugal compressor as well as each between two stages of such a multi-stage centrifugal compressor.

In this case, such a multi-stage centrifugal compressor can also be a transmission compressor.

Claims (9)

Centrifugal compressor ( 100 ) with a housing arrangement ( 1 ) with a first, substantially radially aligned, annular cavity ( 2 ) and a second, substantially axially aligned, annular cavity ( 3 ), which first substantially radially oriented annular cavity (FIG. 2 ) and which second substantially axially aligned annular cavity (FIG. 3 ) via a deflection arrangement ( 4 ) are connected to each other and with a in the second, substantially axially aligned annular cavity ( 3 ) arranged Leitgitter ( 5 ) and with one at an axial outlet ( 25 ) of the second, substantially axially aligned, annular cavity (FIG. 3 ), annular collecting space ( 6 ), characterized in that at a predetermined circumferential position of the collecting space ( 6 ) a barrier rib ( 24 ), which divides a flow entering the collection space into two approximately equal flows. Centrifugal compressor ( 100 ) according to the preceding claim, characterized in that a radial outlet ( 18 ) of an impeller ( 10 ) of the radial compressor ( 100 ) with a radial inlet ( 19 ) of the first, substantially radially oriented, annular cavity (FIG. 2 ) connected is. Centrifugal compressor ( 100 ) according to at least one of the preceding claims, characterized in that the collecting space ( 6 ) with a over a circumference of the annular collecting space ( 6 ) is formed constant cross-section. Centrifugal compressor ( 100 ) according to at least the preceding claim, characterized in that at a predetermined circumferential position of the collecting space ( 6 ) an outlet diffuser ( 7 ) (Discharge nozzle), in particular a substantially radially aligned outlet diffuser ( 7 ), with the collecting space ( 6 ) connected is. Centrifugal compressor ( 100 ) according to claim 4, characterized by an outlet flange ( 8th ), by means of which the outlet diffuser ( 7 ) with a piping system ( 9 ) is connectable. Centrifugal compressor ( 100 ) according to at least one of the preceding claims, characterized in that a profile ( 26 ) of the guide grid ( 5 ) over one Leading edge angle ( 27 ) of the profile ( 26 ) to a flow of a flow medium in the second, substantially axially aligned, annular cavity (FIG. 3 ) and / or that the flow over a cross section (height) of the second, substantially axially aligned annular cavity ( 3 ) to the leading edge angle ( 27 ) of the profile ( 26 ) of the guide grid ( 5 ) is adjusted. Centrifugal compressor ( 100 ) according to at least the preceding claim, characterized in that the first substantially radially oriented, annular cavity ( 2 ) a blading ( 22 ) having. Centrifugal compressor ( 100 ) according to at least one of the preceding claims designed as a single or multi-stage centrifugal compressor ( 100 ). Method for guiding the flow of a flow medium in a radial compressor ( 100 ) according to at least one of the preceding claims, characterized in that the flow medium in the first, substantially radially aligned annular cavity ( 2 ) is guided to the outside in a radial direction, the flow medium in the deflection arrangement ( 4 ) is then deflected substantially in an axial direction, in the second, substantially axially aligned annular cavity ( 3 ) is continued in the substantially axial direction, wherein the flow of a swirl is at least partially removed, the flow medium through the axial outlet ( 25 ) of the second, substantially axially aligned, annular cavity (FIG. 3 ) into the collection room ( 6 ) and at the barrier rib ( 24 ) of the collection space ( 6 ) is divided into two approximately equal flows.

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