Cooling for a fluid flow machine

Abstract

A fluid flow machine, in particular a steam turbine, is provided having a piston-equalizing line which conducts a vapour from a fresh vapour region of a second flow duct to a thrust-equalizing piston, wherein the surface of the piston-equalizing line is enlarged, and wherein the inner surface of the piston-equalizing line is enlarged.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is the US National Stage of International Application No. PCT / EP2012 / 065103 filed Aug. 2, 2012, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP11179311 filed Aug. 30, 2011. All of the applications are incorporated by reference herein in their entirety.FIELD OF INVENTION[0002]The invention relates to a turbomachine comprising a rotor mounted rotatably about an axis of rotation, an inner housing arranged about the rotor and an outer housing arranged about the inner housing, wherein a first flow region and a second flow region, formed in the opposite flow direction to the first flow region, are arranged between the rotor and the inner housing, wherein the rotor has a thrust-equalizing piston, wherein a piston-equalizing line is formed for introducing steam between the inner housing and the thrust-equalizing piston.BACKGROUND OF INVENTION[0003]In turbomachines, s...

AI Technical Summary

Benefits of technology

[0009]A substantial consideration of the invention is thus to extract energy from the hot steam which issues from the second flow duct and is guided via the piston-equalizing line. This occurs, according to the invention, such that the piston-equalizing line outer surface is embodied enlarged with respect to a pipe of identical diameter. This means that, by virtue of the enlarged surface area of the piston-equalizing line, improved heat exchange with the surroundings is possible, as a result of which the temperature of the steam in the piston-equalizing line can drop. Equally, the piston-equalizing line inner surface of the piston-equalizing line is embodied such that it is enlarged with respect to a conventional pipe inner surface which is embodied smooth, as is known. By virtue of this enlarged surface area, improved thermal interaction between the steam in the piston-equalizing line and the piston-equalizing line occurs here, too.

[0010]In a first advantageous development, outer cooling ribs are arranged on the piston-equalizing line outer surface. The embodiment with cooling ribs, wherein as many cooling ribs should be used as possible, makes excellent thermal equalization possible. In this context, it is also to be considered that the larger the surface area of these outer cooling ribs, the better the thermal interaction.

[0011]In a further advantageous development, the outer cooling ribs are arranged in series in the direction of the piston-equalizing line. It is also the case here that the more outer cooling ribs there are, the better the thermal interaction. Advantageously, the outer cooling ribs are formed as annular disks extending in the radial direction with respect to the direction of the piston-equalizing line. Annular disks are characterized by two surfaces arranged parallel to each other and are thus simple to produce. In an advantageous development, the annular disks are arranged at regular intervals.

[0012]Thermal equalization thus takes place in a homogeneous fashion and, in addition, such a piston-equalizing line can have a simpler and less expensive design.

[0013]In a further advantageous development, inner cooling ribs are arranged on the piston-equalizing line inner surface. These inner cooling ribs are arranged in series in the inner circumferential direction and are embodied in such a manner that they do not markedly influence the flow properties of the steam flowing in the piston-equalizing line. For this reason, these inner cooling ribs are embodied as plates, projections or disks in the longitudinal direction or twisted about the longitudinal direction, arranged at regular intervals in an inner circumferential direction. In this case, too, it is important to consider that the greater the surface area achieved by means of the inner cooling ribs, the better the thermal equalization between the steam flowing in the piston-equalizing line and the piston-equalizing line itself.

Problems solved by technology

Modern steam turbines have steam temperatures of over 600° C. Such high temperatures place increased demands on the materials to be used.

However, this entails that the hot steam from the second flow region is guided in part over the thrust-equalizing piston and thus impinges on the outer housing.

The outer housing is thus subject to high thermal loading at this point.

It would not be possible to use a standard material for the outer housing at this point.

Therefore, more expensive materials, for example GGGSIMO, would have to be used at this point.

Such materials are generally comparatively expensive and, moreover, are not easily cast, leading to material defects.

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