Centrifugal compressors axial thrust

Like centrifugal compressor, axial compressor needs shafr seal to reduce the gas leakage. It uses balance drum to reduce the axial hydraulic imbalance and thrust bearing for the remaining axial imbalance. Journal bearings are used for the radial hydraulic imbalance. 

Centrifugal compressor impellers, with the exception of the open impeller, are thrust unbalanced. The machine also has a requirement for a location device to maintain axial clearances. For these reasons, all centrifugal compressors use some form of thrust bearing. 

The bearings used in axial compressors are the same journal and thrust type used in the centrifugal compressor. Refer to Chapter 5 for a complete description of these bearings. 

Non-contact seals with defined narrow clearances, such as labyrinth seals in turbo-machines (Fig. 4.1-47 A), are less problematic owing to the relatively low differential pressures however, the fluid should not have an erosive effect. Differential pressures up to several hundred bar occur at the axial-thrust compensation pistons of centrifugal pumps and compressors, but the fluid expansion is distributed over the many labyrinth stages. 

Figure 8.3 Balancing piston resists axial thrust from the in-line impeller design of a centerline centrifugal compressor...

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