Assembly and method of attaching stub shaft to drum of axial compressor rotor shaft

Abstract

An assembly and method for an axial compressor includes an axial shaft extending between an inlet casing and a discharge casing along the longitudinal length of a compressor housing. The axial shaft assembly includes a first stub shaft, a second stub shaft, and a hollow shaft drum having a longitudinal axis. The first stub shaft and the second stub shaft are coupled to opposing ends of the shaft drum along its longitudinal axis. A plurality of keys is disposed in a radial arrangement near the outer circumference of the first and second stub shafts and the shaft drum. A plurality of pins engage the plurality of keys, whereby the pins prevent the shaft drum from rotating axially relative to the first stub shaft and the second stub shaft and prevent the shaft drum from axially and radially separating from the stub shafts.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates, in general, to axial compressors and, more particularly, to a method of attaching a stub shaft to a drum of an axial flow compressor rotor shaft.[0003]2. Description of the Related Art[0004]Turbo machines, such as centrifugal flow compressors, axial flow compressors, and turbines are utilized in various industries. Axial flow compressors, in particular, have a widespread use in power stations, jet engine applications, gas turbines, and automotive applications. Axial flow compressors are also commonly used in large scale industrial applications, such as air separation plants and hot gas expanders used in the oil refinery industry.[0005]Axial flow compressors generally include a rotating shaft coupled to a central drum having a number of airfoil blades circumferentially arranged and spaced apart in multiple rows along the axial length of the drum. The airfoil blades rotate between a corresponding n...

AI Technical Summary

Benefits of technology

The patent describes an assembly and method for attaching the stub shaft to the shaft drum of an axial flow compressor. The assembly and method eliminates the need for through-bolts to prevent relative motion between the shafts, reducing manufacturing costs and maintenance expenses. The assembly includes a plurality of keys and pins that prevent the shaft drum from rotating axially relative to the first and second stub shafts and prevent the shaft drum from axially and radially separating from the stub shafts.

Problems solved by technology

The magnitude of radial expansion of the stub shaft is usually smaller than the magnitude of radial expansion of the hollow drum, which reduces the effectiveness of the interference fit.

Numerous disadvantages are associated with the use of these conventional devices to prevent relative movement between the stub shaft and the shaft drum.

In embodiments where through-bolts are used, the bolts are subject to harmonic imbalance and resonance as the axial flow compressor is brought up to operating speed because the bolts must be of substantial length to extend along the entire stub shaft length.

High speeds at which stub shafts are usually rotated further complicate these problems.

Additionally, the through-bolts are fastened under a very high pre-stretch condition, which tends to weaken the bolts as the axial flow compressor is operated in multiple cycles.

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