Introduction

A centrifugal compressor is a "dynamic" machine. It has a continuous flow of fluid which receives energy from integral shaft impellers. This energy is transformed into pressure partly across the impellers and partly in the stator section, i.e. in the diffusers.

This type of machine is composed (see fig. 1.1) on an outer casing (A) which contains a stator part, called a diaphragm bundle (B), and of a rotor formed

by a shaft (C), one or more impellers (D), a balance drum (E) and thrust collar (F).

The rotor is driven by means of a hub (G) and is held in position axially by a thrust bearing (I), while rotating on journal bearings (H). The rotor is fitted with labyrinth seals (L) and, if necessary, oil film end seals (M).