Steam turbine exhaust diffuser

Abstract

An axial flow steam turbine includes an exhaust diffuser in the form of a volute for diffusing the exhaust steam and turning the exhaust steam from a generally axial flow direction to a generally radial direction. The volute exit may be at the bottom or to one side of the steam turbine. The volute and casing are independently mounted relative to one another on a foundation with a flexible joint therebetween.

Description

[0001] The present invention relates to steam turbines and particularly relates to an exhaust diffuser in the shape of a volute. BACKGROUND OF THE INVENTION [0002] In prior steam turbines, the inner case of the steam turbine, for example a double flow down exhaust unit has an encompassing exhaust hood split vertically and extending along opposite sides and ends of the turbine. This large box-like structure houses the entire low pressure section of the turbine. The exhaust steam outlet from the turbine is generally conically shaped and the steam exhaust is redirected from a generally axial extending flow direction to a flow direction 90° relative to the axial flow direction. This 90° flow direction may be in any plane, downwardly, upwardly or transversely. Thus the prior exhaust hoods for steam turbines constitute a large rectilinear structure at the exit end of the conical section for turning and diffusing the steam flow at right angles. The steam flow path was thus tortuous resulti...

AI Technical Summary

Problems solved by technology

The steam flow path was thus tortuous resulting in losses and adverse pressure drop.

It will also be appreciated that access to various parts of the turbine, for example, the bearing for maintenance purposes was difficult in that it necessitated the removal of the upper half of the exhaust hood.

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