Turbine arrangement

Patent metadata

Field	Value
Publication number	US-2016146013-A1
Application number	US-201514932089-A
Country	US
Kind code	A1
Filing date	Nov 4, 2015
Priority date	Nov 21, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

The invention relates to a turbine for generating work by a stagewise expansion of a gas, such as steam wherein a downstream stage guide average height is less than an adjacent upstream stage runner average height.

First claim

1 . A turbine for generating work by a stagewise expansion of a gas, the turbine having an axial direction corresponding to an expansion flow of the gas and a radial direction and further comprising:
a casing inner surface; a hub, a first axial stage including:
a first guide fixed to the casing inner surface:
a first runner fixed to the hub downstream of the first guide, having:
a first runner tip radially distal from the hub,
a first runner average radial height between the first runner tip and the hub along an axial midpoint of the first runner;

a second axial stage, downstream of the first axial stage, including:
a second guide, fixed to the casing inner surface, having;
a second guide tip distal from the casing inner surface;

a second guide average radial height between the second guide tip and the casing inner surface along an axial midpoint of the second guide; and
a second runner, fixed to the hub downstream of the second guide, wherein the second guide average height is less than the first runner average height.

2 . The turbine of claim 1 , wherein the hub has a hub radius and the hub radius in a region extending between and including the first guide and the second runner is constant.

3 . The turbine of claim 1 , wherein the hub has a hub radius and the hub radius in a region extending between and including the first guide and the second runner is variable such that the hub radius both increases and decreases.

4 . The turbine of claim 1 further comprising:
a second runner tip radially distal from the hub, wherein:
a first runner radial height between the hub and the first runner tip increases along the axial direction such that a hade angle formed by the first runner tip is constant along the axial direction; and
a second runner radial height increases along the axial direction such that a hade angle formed by of the second runner tip is constant along the axial direction.

5 . The turbine of claim 1 , wherein the first guide, along the casing inner surface in the axial direction, forms a bellmouth shape and the second guide, along the casing inner surface in the axial direction, forms a bellmouth shape.

6 . The turbine of claim 1 further comprising
a first guide tip distal from the casing inner surface, wherein:
a first guide radial height between the casing inner surface and the first guide tip decreases along the axial direction such that the first guide tip forms a bellmouth shape along the axial direction; and
a second guide radial height between the casing inner surface and the second guide tip decreases along the axial direction such that the first guide tip forms a bellmouth shape along the axial direction.

7 . The turbine of claim 1 wherein a K value of the first runner varies from 0.25 at the hub to 0.16 at the first runner tip.

8 . The turbine of claim 7 wherein the K value of the second guide varies from 0.15 at casing inner surface to 0.25 at the second guide tip.

9 . The turbine of claim 1 , wherein the turbine is a steam turbine and the first axial stage is a first axial stage of the turbine configured with a root reaction of 30%.

10 . The turbine of claim 9 wherein a back surface deflection of the first runner, the second runner or both the first runner and the second runner is between 25 degree and 35 degrees.

11 . The turbine of claim 9 wherein the first axial stage is configured such that in normal operation a ratio of a disc circumferential speed at the hub and a velocity equivalent of stage isentropic total to status heat drop lies in a range of 0.5 to 0.56.

12 . The turbine of claim 9 wherein a ratio of a second guide tip radius to a hub radius is less than 1.3.

13 . The turbine of claim 1 wherein the turbine is a gas turbine and a back surface deflection of the first runner and/or the second runner is between 25 degrees and 30 degrees.

Assignees

• Alstom Technology Ltd

Inventors

• Haller Brian Robert

Classifications

• F01D5/145

  Means for influencing boundary layers or secondary circulations (for compressors F04D29/68) · CPC title

• F05D2250/80

  Size or power range of the machines · CPC title

• F05D2220/32

  in gas turbines · CPC title

• F01D5/147

  Construction, i.e. structural features, e.g. of weight-saving hollow blades (F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18) · CPC title

• F01D9/041

  using blades (F01D5/148 takes precedence) · CPC title