Multistage Compressor

Abstract

The axial-flow low pressure section and radial-flow or diagonal-flow high pressure section are separated by a recooler in which the working fluid is first deflected outwardly from the rotor, spread fanwise in a channel around and perpendicularly of the rotor, then deflected towards the rotor and fed perpendicularly through a channel to the compressor axis. In addition, a cooling element is disposed in one of the channels for cooling of the working fluid.

Description

This invention relates to a multistage compressor.

Heretofore, multistage compressors have been known to have a rotor on which an axial-flow low-pressure section is disposed with stages for compressing a working fluid without cooling to a maximum permissible temperature. The low-pressure section has been followed by a radial-flow (or diagonal-flow) high-pressure section while a recooler has been disposed in the fluid flow path between the low-pressure section and high-pressure section. Compressors, of this kind are known, for instance from Motortechnische Zeitschrift, Jahrgang 13, Nr. 2, February 1952.

However, these known compressors have been of relatively long dimensional lengths. As a result, such has resulted in excessive whirling. Also, the number of radial-flow stages has been limited.

Accordingly, it is an object of the invention to provide a compressor of very small dimensions.

It is another object of this invention to reduce whirling in a compressor.

It is another object of this invention to be able to use two or more consecutive radial-flow stages without axial reversal of the working fluid.

Briefly, the invention provides a multistage compressor having a rotor, an axial-flow low-pressure section and a radial-flow high pressure section with a means for deflecting a working fluid leaving the low-pressure section first away from the rotor and then towards the rotor for entry perpendicularly into the radial-flow high pressure section as well as a cooling element for cooling the working fluid flowing into the high-pressure section. The means for guiding the working fluid between the low-pressure and high-pressure sections includes a first deflector section, a first channel, a second deflector section and a second channel, in that order. The first deflector section deflects the working-fluid flow outwardly away from the rotor. The first channel spreads the flow out fanwise around and perpendicularly to the compressor axis. The second deflector section deflects the flow back towards the shaft and the second channel supplies the flow to the high-pressure section entry perpendicularly to the compressor axis. At least one of the two channels has at least one cooling element disposed therein.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

The drawing illustrates a cross-sectional view of a multistage compressor according to the invention.

Referring to the drawing, the multistage compressor has a rotor 1 on which six axial sets 2-7 of axial-flow blades are mounted in a first section and three radial-flow rotors 8-10 in a second section. Extending around rotor 1 is a casing 11 having an entry channel 12 for the entry of fluid for compression. A channel 13 is disposed at the opposite end for exiting of compressed fluid. The axial-flow section of the compressor comprises a blade carrier 14 in which seven sets 15-21 of guide blades are mounted. Each individual blade of the sets 15-21 has a root which is mounted in the blade carrier and on which bent levers 24, engaging in circular grooves 22 in adjustment cylinder 23, are disposed. A toothed rack 25 is positioned at the bottom of the cylinder 23 to enable the cylinder 23 to be adjusted to suit operating requirements by means of a pinion 26 of a motor 27.

In addition, the adjustable guide blades 15-21 which are adjustable around a radial axis are followed by at least one axial-flow stage having an adjustable exit guide blade 21 and a non-adjustable entry guide blade for the channel 29.

Disposed between the last set 21 of axial-flow rotor blades and the first radial-flow rotor 8 is a deflector part 28 which is connected to the casing 11 and in which the axial flow from the first section of the compressor is converted into an outwardly directed radial flow. Following section 28 is a channel 29 which is directed radially outwards and which acts as a diffusor and through which the fluid flows to go through a second deflector section 30 into a second channel 31. The second channel 31 extends radially inwards. After further deflection, the flow enters the first radial flow rotor 8. The inwardly directed channel 31 has cooling elements 32 which reduce the heat of compression acquired by the fluid in the axial-flow section of the compressor. There is, therefore, recooling of the fluid being compressed, and so a very high compression ratio can be used as early as the first radial-flow stage before any further cooling is given by elements 33. After compression in the next rotor 9, the fluid is recooled by elements 34 before being compressed to its final pressure by rotor 10.

The cooling elements 32 together have a larger cooling area than do the elements 33, 34, since the axial-flow section of the compressor compresses the fluid to the maximum permissible temperature, whereas in a radial-flow stage only the greatest pressure difference, with a reduced temperature rise occurs.

The diffusor type radial-flow channel 29 can have appropriate guide elements which can also be devised as cooling elements.

The invention thus provides a compressor which can be constructed of relatively short lengths. Because of this, the rotor bearings can be closely spaced with a resultant reduction of whirling. Also, a number of radial-flow stages can be used as there is no axial reversal of the working fluid flow.

Claims

1. A multistage compressor comprising

a casing;

a rotor within said casing;

an axial-flow low-pressure section having a plurality of stages about said rotor for compressing a working fluid without cooling to a maximum permissible temperature;

a radial-flow high-pressure section downstream of said low-pressure section on said rotor;

means within said casing between said low-pressure section and said high pressure section including a first deflector section for deflecting the working fluid perpendicularly outwardly away from said rotor, a first channel for thereafter spreading out the working fluid flow fanwise around and perpendicularly to said rotor, a second deflector section for deflecting the fluid perpendicular to said rotor towards said rotor and thereafter into said high-pressure section; and

at least one cooling element in said means for cooling the working fluid passing through said means to reduce the heat of compression acquired by the flow in said axial-flow section and to achieve a very high compression

2. A multistage compressor as set forth in claim 1 wherein said cooling

3. A multistage compressor as set forth in claim 1 wherein said stages includes axial flow blades for compressing the working fluid without

4. A multistage compressor as set forth in claim 3 wherein said blades of

5. A multistage compressor as set forth in claim 5 wherein at least one stage downstream of said adjustable blades includes non-adjustable blades.

6. A multistage compressor as set forth in claim 1 wherein said high-pressure section includes at least two radial-flow rotors and a second cooling element between said radial flow rotors for cooling the

7. A multistage compressor as set forth in claim 1 which further includes an adjustable exit guide blade downstream of said stages of said low-pressure section and a non-adjustable entry guide blade between said exit guide blade and said means.