RU2338095C1 - Centrifugal compressor - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: centrifugal compressor comprises a housing with covers, a shaft with impellers, a balance chamber, an inlet chamber with a separating rib and a gas duct communicating the inlet chamber with the behind-the-balance-chamber space. The said separating rib is furnished with an inner space, on one side communicating with the gas duct and, on the other side, via the channels arranged in the separating rib walls, primarily on the rotor shaft side, with the suction chamber. The gas blow-by from the increased pressure space into the reduced pressure space allow the main and by-passed gas flows direction coincide which rules out abnormal main flow disturbance, makes it symmetric and the speed field regular at the impeller inlet.

EFFECT: reduced drag, higher efficiency.

2 dwg

Description

The invention relates to mechanical engineering and can be used to create compressors, including compressors for the transport of natural gas.

In compressor engineering, to reduce the resulting force acting on the rotor of a multistage compressor, gas bypass (bypassing) from the cavity with increased pressure to the lower pressure cavity is widely used, for which the space behind the discharge piston (dummies) is communicated with the compressor suction pipe.

A compressor is known (USSR AS No. 324900, F04D 17/08, F04D 29/42, publ. 08.11.79), in which the gas is transferred from the cavity of the knee of the compressor diffuser into the annular gap between the wall of the diaphragm of the stator part and the cover disk of the worker wheels. Moreover, the bypass channel is located directly in the body of the stator part (diaphragm), and the bypass hole. located in close proximity to the labyrinth seal sleeve of the cover disk.

A centrifugal compressor is known (USSR AS No. 1455047, F04D 17/08, publ. 01/30/89), in which the gas is transferred from the conceptual discharge cavity of the centrifugal compressor to the cavity of the suction chamber using a pipe connecting the above cavities.

A common disadvantage of the known structures mentioned is that in the area of the opening of the bypass channel through which the compressed gas is bypassed due to the dummies cavity, a local disturbance (deviation) of the main gas flow occurs. When two gas flows interact, a redistribution of the pressure field occurs with the formation of a non-uniform velocity field in the suction chamber, which leads to uneven gas flow at the inlet to the first stage of the compressor and, consequently, leads to internal pressure losses and a decrease in the polytropic efficiency of the compressor.

A known centrifugal compressor (Rice V.F. Centrifugal compressor machines. Publishing house. "Mechanical Engineering". Moscow-Leningrad. 1964, p. 219, Fig.6.9), which contains a housing with nozzles. suction and discharge. A shaft with impellers and a dummy mounted on it is installed in the housing. Behind the dummis, an unloading cavity is formed in the housing, which is connected through the pipeline to the internal cavity of the suction pipe through an opening in the wall of the suction pipe to which the pipe is connected.

The disadvantage of such a design scheme for transferring the working gas to the suction cavity is the asymmetric local injection of part of the gas with increased pressure at a certain angle to the main stream. With asymmetric gas injection (through one hole), two flows interact with the disturbance of the main gas flow in the suction chamber with the formation of a local zone of increased pressure, which is an obstacle that the main gas flow is forced to overcome with a deviation. In this case, the velocity field of the flow is redistributed, which leads to its unevenness at the entrance to the first stage of the compressor, and, accordingly, to an increase in the volumetric internal losses of the compressor, which reduce its polytropic efficiency.

The technical task of the proposed technical solution is to remedy these disadvantages by improving the conditions for bypassing the secondary gas stream from the back-discharge discharge cavity into the suction cavity.

The technical result is achieved by the fact that in a centrifugal compressor containing a housing with covers, a shaft with impellers, a dummy, a suction chamber with a dividing rib, a gas duct communicating with a suction chamber with a ponderous cavity, the dividing rib is made with an internal cavity, which is connected on one side with gas duct, and on the other through the channels in the wall of the dividing rib, mainly from the side of the rotor shaft, with a suction cavity.

Figure 1 shows the meridian (longitudinal) section of the compressor, figure 2 is a view along the arrows section AA.

The centrifugal compressor comprises a housing 1, covers 2, 3 mounted in a housing on a shaft 4, impellers 5, 6 and dummies 7, forming a gap 9 with a labyrinth sleeve 8, a ponder cavity 10, which is connected to the side bosom 11 of the wheel 6 and communicates with the gas duct (internal bypass channels 12, 13 and pipe 14) with an internal cavity 15 of the dividing rib 16 through the exhaust channels 17 with the suction cavity 18. The cover 3 is connected to the elements of the discharge chamber 19.

When the compressor is operating, the main gas stream is sucked through the inlet pipe (not shown in FIG. 1) of the housing 1, enters the suction cavity 18, flowing around the surface of the cover 2 and the dividing rib 16, is compressed by the impellers 5, 6 mounted on the shaft 4 together with the dummis 7, and is sent to the discharge chamber 19, attached to the cover 3, and then from it to the outlet pipe (not shown in FIG. 1) of the housing 1. A part of the gas in a compressed state comes from the side sinus 11 of the wheel 6 through the gap 9 between the dummies 7 and labyrinth sleeve 8 into the conceptual stripes 10 in the cover 3. Next, the gas is directed through the bypass channels 12, 13 of the pipe 14 into the cavity 15 of the dividing ribs 16 and then through the exhaust channels 17 into the suction cavity 18.

Bypassed gas flow, passing the exhaust channels 17, is mixed along the path in the suction cavity 18 with the main gas stream and sent to the entrance to the first impeller 5. The cycle of bypassing a portion of the compressed gas from the concept chamber 10 to the suction cavity 18 is repeated.

The main and bypassed gas flows in the suction cavity are almost equally directed, there is no abnormal perturbation (deviation) of the main stream, the flow is symmetrical and the velocity field is uniform at the inlet to the impeller, which reduces internal volumetric pressure losses in the compressor and increases its efficiency.

Claims (1)

A centrifugal compressor comprising a housing with covers, a shaft with impellers, a dumis, a suction chamber with a dividing rib, a gas duct communicating with a suction chamber with a ponder cavity, characterized in that the dividing rib is made with an internal cavity that is connected to the gas duct on one side, and on the other, through channels in the wall of the dividing rib, mainly from the side of the rotor shaft, with a suction cavity.

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