GB2024328A

GB2024328A - Multi-stage centrifugal compressor

Info

Publication number: GB2024328A
Application number: GB7920908A
Authority: GB
Original assignee: Pumpen & Verdichter Veb K
Current assignee: Pumpen & Verdichter Veb K
Priority date: 1978-06-28
Filing date: 1979-06-15
Publication date: 1980-01-09
Also published as: FR2429912A1; JPS5517687A; DE2921965A1; IT7949494A0; IT1117240B; DD136876A1

Abstract

Each stage 1, 2, 3 is driven independently of any other stage by its own drive 4, 4', 4'', such as a D.C. electric motor fed with rectified A.C. current, an internal combustion engine or a turbine. Intercoolers 7, 7', an inlet silencer 5 and, it may be, an outlet silencer are provided. <IMAGE>

Description

SPECIFICATION A multi-stage radial centrifugal compressor unit The invention relates to a multi-stage radial centrifugal compressor unit having axial inlet pipes for its individual compressor stages, diffuser-like deflection chambers for guiding the medium being compressed into the next compressor stage, and intermediate coolers arranged between the compressor stages.

A multi-stage radial compressor of compact constructional form is known, the impellers of which are driven by a common gear. The pressure-conversion housing and the deflection chambers associated with the individual compressor stages are assembled to form a single structural part which forms that end wall of the compressor housing which is on the driving side and on which the gearbox is flanged. On that end face of the compressor housing which is opposite the gearbox and coaxially to the impeller axis of each compressor stage is flanged an independent cooler housing. The pressure-conversion housing of each compressor stage is constructed as a spiral housing, from the largest cross-section of which is led out tangentially a diffuser increasing uniformly in size and opening into the deflection chamber of the following stage (German Offenlegungsschrift 21 54 267).The disadvantage of this invention consists in that each impeller of the compressor is driven by a separate pinion shaft, as a result of which there are high bearing losses due to the large number of bearings, and compensation for axial thrust due to a possible opposite arrangement of the stages is lacking and, in addition, relatively high external losses due to leakage occur.

Another multi-stage, radial centrifugal compressor is known, in which a pair of impellers is arranged back to back on each pinion shaft only at one end on that side of the gear further from the drive means.

This arrangement is particularly suitable for use with even numbers of stages. However, with odd numbers of stages, it is also possible for a single impeller to be arranged on a pinion shaft on the side further from the drive means. The intermediate coolers can be arranged in vertical individual housings, or nests of intermediate coolers are arranged with the compressor stages in common housings (German Offenlegungsschrift 25 18 628). The disadvantage of this compressor consists in that the inlet flow to each one of the impellers arranged back to back is unfavourable and the wear on the compressor unit is relatively high because of the gear and of the oil aggregate which is connected therewith.

In contrast to the known radial centrifugal compressors, the purpose of the present invention is to develop a centrifugal compressor unit which is economically superior as regards its manufacture, purchase, installation and operation.

The purpose of the invention is to provide a multi-stage radial centrifugal compressor unit which can be better controlled, in which the inflow and outflow of the coolers and the supply to the next impeller have a substantially improved design, and which operates more reliably.

The invention provides a multi-stage radial centrifugal compressor unit having axial inlet pipes for its individual compressor stages, diffuser-like deflection chambers for guiding the medium being compressed into the next compressor stage, and intermediate coolers arranged between the compressor stages, wherein each compressor stage of the compressor is driven independently of any other stage by its own drive at a speed which is the optimum speed for that stage and which is either constant or variable.

Preferably the compressor is provided with an inlet silencer situated upstream of the first stage and/or outlet silences situated downstream of the last stage. The speed of each of said drives may be adjustable.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a plan view of a three-stage compressor unit, and Figure 2 is a side view of of a two-stage compressor unit with a variable arrangement of stages.

The centrifugal compressor unit shown in Figure 1 comprises a first stage 1 to the inlet of which is attached an inlet silencer 5 and the impeller of which is driven by a drive 4. The outlet of the first stage 1 is connected via a first deflection chamber 6, constructed similarly to a diffuser, to a first intermediate cooler 7 which is connected to the inlet of a second stage 2. The impeller of the second stage 2 is driven by a drive 4' which is independent on the drive 4. The outlet of the second stage is connected via second deflection chamber 6' to a second intermediate cooler 7' which is connected to the inlet of a third stage 3, which, in the illustrated embodiment, is the last stage. The impeller of the third stage is driven by a drive 4" which is independent on the drives 4 and 4'. The outlet of the third stage may be connected to an outlet silencer.The whole compressor unit is of a compact constructional form and is mounted on a base frame 8.

In operation the medium to be compressed, e.g.

air, is sucked in by the first stage 1 through the inlet silencer 5, is compressed and passes through the first deflection chamber 6 and first intermediate cooler 7 to the second stage 2 where it is further compressed and passes through the second deflection chamber 6' and the second intermediate cooler 7' to the third stage 3 where it is further compressed and supplied, e.g. through an outlet silencer, out of the compressor unit, e.g. to a device for storing the compressed medium.

The two-stage compressor unit illustrated in Figure 2 is similar to that illustrated in Figure 1 except that the individual compressor stages 1, 2 and their individual drives 4, 4' are arranged one higher than the other, preferably one above the other. The arrangement of all compressor stages and all drives on one side of the unit has advantages in certain applications.

In this specification and claims the noun "drive" as used in connection with a compression unit according to the invention means a driving device, such as a motor or engine.

The advantages of the invention consist in that it dispenses with the need for the customary gear and the necessary oil aggregate for supplying the gear, so that the reliability in operation is substantially improved due to the reduction of components which are subject to wear. In addition the installation and dismanting of separate structural groups is consid erably facilitated by the readily visible arrangement and good access to all structural groups.

Because the drives of the individual compressor stages are independent of one another and the impellers of the individual stages may run at a constant and/or a variable speed, the most important advantage consists in that it is possible to meet the specific requirements of the individual stages. So for instance the drive 4, and consequently the impeller of the low-pressure first stage 1 may rotate faster than the drive 4', and consequently the impeller of the high-pressure second stage 2. The favourable flow caused by the floatingly arranged impellers and resulting from the advantageous arrangement of the compressor stages leads to saving in energy consumption.

Claims

1. A multi-stage radial centrifugal compressor unit having axial inlet pipes for its individual compressor stages, diffuser-like deflection chambers for guiding the medium being compressed into the next compressor stage, and intermediate coolers arranged between the compressor stages, wherein each compressor stage of the compressor is driven independently of any other stage by its own drive at a speed which is the optimum speed for that stage and which is either constant or variable.

2. A compressor unit according to Claim 1 wherein an inlet silencer is situated upstream of the first stage andíor an outlet silencer is situated downstream of the first stage.

3. A compressor unit according to Claim 1 or 2 wherein the speed of each said drive is adjustable.

4. A compressor unit according to any one of Claims 1 to 3 wherein each said drive is å directcurrent motor fed through a diode orthyristor rec tifierfrom an alternating or three-phase current supply, a frequency-controlled three-phase motor, an internal combustion engine or a turbine.

5. A multi-stage radial centrifugal compressor unit constructed, arranged, and adapted to operate, substantially as herein described with reference to, and as shown in Figure 1 or Figure 2 of the accom panying drawings.