Anchorage system for the rotors of a rotating fluid machine

Abstract

An anchorage system is described for a rotor (18) of a rotating fluid machine (10). The rotor (18) has a profile which comprises a first front surface (24) substantially concave and a second rear surface (26) substantially convex, opposite to the first front surface (24). The rotor (18) also has a central portion (28), configured for being constrained with interference on a rotating shaft (14) of the machine (10) and equipped with a shank (30) connected with the second rear surface (26). The system comprises at least one check ring (32) assembled by interference on the shank (30) of the rotor (18). The check ring (32) has a first internal circumferential surface (34), coupled by interference with the shank (30), and a second internal circumferential surface (36), coupled by interference with the shaft (14), to increase the torque which can be transmitted from the shaft (14) to the rotor (18).

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an anchorage system for the rotors of a rotating fluid machine and, more specifically, to an anchorage system between a rotor and rotating shaft of a compressor of the centrifugal type.[0003]2. Background of the Invention[0004]It is known that a compressor is a machine capable of raising the pressure of a compressible fluid (gas) with the use of mechanical energy. Among the various types of compressors used in industrial process plants, so-called centrifugal compressors can be mentioned, in which the energy is supplied to the gas in the form of centrifugal acceleration due to the rotation, generally driven by a driver (electric motor or vapour turbine), of an organ called rotor or turbine wheel.[0005]Centrifugal compressors can be provided with a single rotor, in the so-called single-phase configuration, or with several rotors situated in series, in this case called multiphase compressor...

AI Technical Summary

Benefits of technology

"The invention provides an anchorage system for the rotors of a rotating fluid machine that can guarantee the transmission of power by interference between shaft and rotor, especially in the case of the use of rotors made of aluminum alloys. The system allows the assembly of rotors made of aluminum alloys also along the shaft of a compressor of the multiphase type and not only in correspondence with one of its ends, guaranteeing adequate centering and torque transmission. The system includes a rotor with a profile that comprises a first front surface substantially concave and a second rear surface substantially convex, opposite to the first front surface, and a shank connected with the second rear surface of the rotor. The system further includes at least one check ring assembled by interference on the shank of the rotor, which increases the torque which can be transmitted from the shaft to the rotor."

Problems solved by technology

One of the problems which arise with rotors of the known type, especially if made of light metallic alloys (for example aluminum) rather than steel in order to be able to operate with particular fluids, is maintaining a sufficient interference with the shaft during the functioning of the compressor.

The radial dilation of the rotor hub, especially if made of an aluminum alloy, due to thermal dilation and also to the effect of centrifugal forces, is in fact extremely high with respect to the same end-products made of steel, consequently facilitating the total or partial loss of interference, and in any case insufficient for transmission of the torque.

In particular, rotors made of light aluminum alloy cannot be simply fitted onto the shaft, as these aluminum alloys have a low elastic modulus, which corresponds to a low rotor hub-shaft specific contact pressure and a high thermal dilation coefficient, which causes a major loss in interference during the functioning of the rotor.

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