CENTRIFUGAL COMPRESSOR

Abstract

A centrifugal compressor includes a housing having a part joint plane which extends parallel to or along a machine axis, and a shaft extending along the machine axis and having a first shaft end and a second shaft end. At least one impeller is mounted on the shaft. A collector helix is arranged downstream of the at least one impeller and collects the compressed fluid prior to an outflow into a following machine module. The collector helix is arranged on the first shaft end. A drive is arranged on the first shaft end. An axial intake at an overhang stage of the centrifugal compressor is provided on the shaft on the second shaft end. The collector helix is realized as a single piece in the circumferential direction and is flanged to the housing of the centrifugal compressor.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage of International Application No. PCT/EP2011/057660, filed May 12, 2011 and claims the benefit thereof. The International Application claims the benefits of German application No. 10 2010 020 891.4 DE filed May 18, 2010. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a centrifugal compressor having a shaft which extends along a machine axis, there being a drive on the side of a collector helix, which collects a compressed fluid downstream of at least one impeller upstream of an outflow into a following machine module, which drive is arranged on a shaft end which is guided out of a housing of the centrifugal compressor, wherein an axial intake is provided on an overhang stage of the centrifugal compressor on an opposite shaft end of the shaft.

BACKGROUND OF INVENTION

These types of compressors are used in particular for compressing large volume flows (e.g. 600,000 m³ per hour) at pressures of, for example, 8 bar. The advantage of the axial intake, in this case, is that the intake surface is particularly large and at the same time the maximum diameter of the impellers remains moderate such that the machine can be operated at higher speeds without overloading the materials of the rotating parts. Said machines are particularly preferred for air compression.

In the so-called collector helix, the compressed process fluid is collected behind the impeller and flows into a machine module downstream, for example a cooling unit. As a rule, such a collector helix is an annular chamber realized in a slightly helical manner, the cross sectional area of which widens in the circumferential direction as it gets closer to the outlet into the following unit in the direction of rotation. Said expensive geometry is due to the fact that unfavorable flow contours, which generate high pressure losses in the collector chamber, are also particularly damaging for the efficiency as a result of the increased density of said fluid. In the case of conventional compressors, the collector helix, just as the housing, has a horizontal part joint which either generates an unfavorable deposition in the flow contour of the collector helix, which leads to pressure losses, or requires expensive finishing which has to be carried out in a time-intensive, individualized manner on the element which is realized, as a rule, as a cast part.

Documents DE 38 35 341 A1 and U.S. Pat. No. 2,578,617 A already make known centrifugal compressors with an opening for compressing a fluid, said centrifugal compressors having a housing which has a part joint plane, which extends parallel to a machine axis and has a shaft which extends along the machine axis, having at least one impeller and one collector helix which is arranged downstream of the at least one impeller and collects the compressed fluid upstream of an outflow into a following machine module, wherein the collector helix is arranged on the first shaft end. In addition, the apparatuses disclosed in said documents include a drive which is arranged on the first shaft end, wherein an axial intake of the centrifugal compressor is provided on the second shaft end.

SUMMARY OF INVENTION

Consequently, it is the object of the invention to improve the centrifugal compressor defined in the introduction in such a manner that, on the one hand, production expenditure is reduced and, on the other hand, no high pressure losses are generated in the collector helix.

It is proposed as claimed in the invention that the helix is realized as a single piece in the circumferential direction and is flanged to the housing of the centrifugal compressor.

The advantage of the collector helix being realized in a single piece is that the helix, which is realized as a rule as a cast part, does not form any deposition generated by a part joint on the flow contour which either leads to unwanted pressure losses as a result of a disturbance in the flow or requires an expensive individualized finishing process.

Besides this, the advantage of realizing the helix in a single piece is that as a result of the high pressure of the outgoing fluid, the helix is deformed most extensively in a rotationally symmetrical manner and not, as in the case of conventional designs, severely distorted by the separation in a part joint. In particular, no part joint is opened as a result of the outgoing pressure and there is also no ovalizing of the flange or of the connecting diameter of the collector helix, realized as a rule in a round manner.

An advantageous further development of the invention provides that the helix is realized as support of a shaft bearing for the bearing arrangement of the shaft. As a result, on the one hand a particularly compact design is achieved and, on the other hand, the tolerance chain between the impellers of the shaft and opposite inside surfaces of the housing is particularly short.

Additionally advantageous is a design of the collector helix as carrier of a shaft seal on the side of that shaft end on which the drive of the centrifugal compressor is arranged and the shaft is guided out of the housing of the centrifugal compressor. In particular in combination with the design of the helix as carrier of the bearing, there is a particularly short tolerance chain between the bearing arrangement of the shaft and the surfaces of the seal which are opposite the shaft such that particularly small seal clearances can be realized or the seal has a particularly low degree of laxity.

In an expedient manner, the collector helix is realized as a component closing off the housing of the centrifugal compressor on the one side similar to a cover. The number of components is reduced correspondingly.

The directional specifications—axially, radially and circumferential direction—always relate to the machine axis.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below in more detail by way of a special exemplary embodiment with reference to a drawing, further possibilities of the conversion of the invention presenting themselves to the expert apart from said exemplary embodiment in particular from an arbitrary combination of the features defined in the dependent sub-claims. In which drawing:

FIG. 1 shows a schematic representation of a longitudinal section through a compressor as claimed in the invention.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a schematic longitudinal section through a compressor CO as claimed in the invention. Essential component parts of the compressor CO are a housing C, a shaft SH, the impellers IM—only one of which is shown and supports an overhang stage ST, a collector helix CC which is flanged to the housing C and a drive D which rotates the shaft SH.

The shaft SH extends along a machine axis AX which is at the same time the axis of rotation of the drive D. A process fluid F is sucked in axially by the compressor CO and enters into an overhang stage ST, continues to be compressed downstream by means of the impellers IM and enters into a last stage LST in order to be collected finally in the collector helix CC for entry into the machine module downstream. The shaft SH is mounted in two radial bearings BE1, BE2. The shaft SH has a first shaft end SE1 and a second shaft end SE2, the first shaft end SE1 being driven by the drive D and the second shaft end SE2 carrying the overhang stage ST. The term shaft end SE1, SE2 in the invention refers to a region of the shaft which extends from the respective end of the shaft in the direction of the shaft center, approximately a third of the overall shaft length being designated in each case as the shaft end in the terminology of the invention. Apart from the torque-transmitting connection to the drive D, the collector helix CC, the second radial bearing BE2 and a shaft seal SHS are also arranged in the region of the first shaft end SE1. Whilst the housing C has a part joint in the extension of the machine axis AX, the collector helix CC is in one piece in the extension of the machine axis or parallel thereto and is flanged to the housing C by means of first fastening elements SM1. At the same time, the collector helix CC is carrier of the second radial bearing BE2 and of the shaft seal SHS. The advantage of the one-piece design of the collector helix, which is realized as a cast part, is that said collector helix in the circumferential direction does not have any deposition, brought about otherwise by a part joint which could cause flow losses. The fastening of the second radial bearing BE2 and of the shaft seal SHS to the collector helix CC results in as short a tolerance chain as possible between the radial bearing BE2 and the shaft seal SHS such that radial clearances of the shaft SH in the shaft seal SHS, necessary for example for thermal expansion, are able to be minimal. Particularly good efficiency can be achieved in this way.

Claims

1-2. (canceled)

3. A centrifugal compressor for compressing a fluid, the centrifugal compressor comprising:

a housing which has a part joint plane which extends parallel to or along a machine axis,

a shaft which extends along the machine axis and has a first shaft end and a second shaft end,

at least one impeller which is mounted on the shaft,

a collector helix which is arranged downstream of the at least one impeller and collects the compressed fluid prior to an outflow into a following machine module, wherein the collector helix is arranged on the first shaft end, and

a drive which is arranged on the first shaft end,

wherein an axial intake at an overhang stage of the centrifugal compressor is provided on the shaft on the second shaft end,

wherein the collector helix is realized as a single piece in the circumferential direction and is flanged to the housing of the centrifugal compressor.

4. The centrifugal compressor as claimed in claim 3, wherein the collector helix is realized as support of a radial bearing for the bearing arrangement of the shaft.