Turbine diaphragm construction

Patent metadata

Field	Value
Publication number	US-9840928-B2
Application number	US-201313863685-A
Country	US
Kind code	B2
Filing date	Apr 16, 2013
Priority date	Apr 26, 2012
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

An axial flow turbine diaphragm is constructed without welding or other metal fusion or melting techniques. Static blade units are attached to inner and outer diaphragm rings by radially inner platform portions that engage the radially inner ring, and radially outer platform portions that engage the radially outer ring, the inner platform portions being elongate in the circumferential direction of the turbine diaphragm and the outer platform portions being elongate in a direction compatible with the stagger angle of the aerofoils. The outer circumference of the radially inner ring has a blade unit retaining feature of complementary shape and orientation to the inner platform portions of the static blade units, and the inner circumference of the radially outer ring is provided with a plurality of blade unit retaining features of complementary shape and orientation to corresponding outer platform portions of the static blade units.

First claim

The invention claimed is:

1. An axial flow turbine diaphragm comprising:
(a) a radially inner diaphragm ring having a circumferential direction;
(b) a radially outer diaphragm ring having a circumferential direction;
(c) a plurality of static blade units arranged between the radially inner diaphragm ring and the radially outer diaphragm ring, each static blade unit of the plurality of static blade units comprising:
an aerofoil portion;
a radially inner platform portion that engages the radially inner diaphragm ring; and
a radially outer platform portion that engages the radially outer diaphragm ring; wherein:
(i) the radially inner diaphragm ring is provided with blade unit retaining means that retains the radially inner platform portions to the radially inner diaphragm ring;
(ii) the radially outer platform portion includes a length and a width, the length being greater than the width, and the length being disposed on the radially outer diaphragm ring so as to elongate in a direction oriented to match a placement direction of the aerofoil portion that is generally transverse to the circumferential direction of the radially outer diaphragm ring; and
(iii) an inner circumference of the radially outer diaphragm ring is provided with a plurality of blade unit retaining features, each blade unit retaining feature being of complementary shape and orientation to the corresponding radially outer platform portion of the each static blade unit of the plurality of static blade units, thereby to retain the radially outer platform portion to the radially outer diaphragm ring, wherein the radially inner platform portion of each of the plurality of static blade units includes a length and a width, the length of the radially inner platform portion being greater than the width of the radially inner platform portion, and the length of the radially inner platform portion being disposed on the radially outer diaphragm ring so as to elongate in the circumferential direction of the radially inner diaphragm ring, and
wherein the length of the radially outer platform portion of each of the plurality of static blade units is elongate in a direction transverse to the length of the radially inner platform portion.

2. The axial flow turbine diaphragm according to claim 1 , in which the radially outer platform portions of the plurality of static blade units alternate in the circumferential direction with exposed portions of the inner circumference of the radially outer diaphragm ring.

3. The axial flow turbine diaphragm according to claim 1 , in which the radially inner platform portions of the plurality of static blade units are elongate in the circumferential direction of the axial flow turbine diaphragm and an outer circumference of the radially inner diaphragm ring is provided with a blade unit retaining feature of complementary shape and orientation to the radially inner platform portions of the plurality of static blade units, whereby the radially inner platform portions are retained to the radially inner diaphragm ring.

4. The axial flow turbine diaphragm according to claim 3 , in which the radially inner platform portions of the plurality of static blade units are flanked on axially opposed sides of the radially inner platform portions by exposed portions of the outer circumference of the radially inner diaphragm ring.

5. The axial flow turbine diaphragm according to claim 3 , in which confronting ends of the radially inner platform portions butt up to each other when inserted into the blade unit retaining means of the radially inner diaphragm ring, such that the radially inner platform portions extend continuously around the outer circumference of the radially inner diaphragm ring of the axial flow turbine diaphragm in the circumferential direction.

6. The axial flow turbine diaphragm according to claim 1 , in which the radially inner platform portions and the radially outer platform portions of the plurality of static blade units have radial cross-sections shaped to fit the blade unit retaining features in the form of slots or grooves having radial cross-sections with undercut or re-entrant shapes.

7. The axial flow turbine diaphragm according to claim 6 , in which the radially inner platform portions of the plurality of static blade units are T-shaped in cross-section, the cross-bar of the T-shape being positioned radially inwards of the stem of the T-shape.

8. The axial flow turbine diaphragm according to claim 6 , in which the radially outer platform portions of the plurality of static blade units are T-shaped in cross-section, the cross-bar of the T-shape being positioned radially outwards of the stem of the T-shape.

9. The axial flow turbine diaphragm according to claim 1 , in which the radially inner diaphragm ring and the radially outer diaphragm ring each comprises at least two segments.

10. The axial flow turbine diaphragm according to claim 9 , in which the radially inner diaphragm ring has an even number of segments comprising at least four segments.

11. The axial flow turbine diaphragm according to claim 10 , wherein each of the at least four segments of the radially inner diaphragm ring comprises an arc of ninety degrees.

12. The axial flow turbine diaphragm according to claim 9 , in which the segments of the radially outer diaphragm ring are united with each other on joint planes at diametrically opposed sides of the radially outer diaphragm ring.

13. The axial flow turbine diaphragm according to claim 9 , in which the segments of the radially outer diaphragm ring are united with each other on joint planes that are angled to be compatible with the direction of the aerofoil portions of the plurality of static blade units.

14. The axial flow turbine diaphragm according to claim 9 , in which the segments of the radially outer diaphragm ring are united with each other by bolted joints.

15. A method of assembling the axial flow turbine diaphragm of claim 9 , comprising the steps of:
(a) attaching the plurality of static blade units to the segments of the radially outer diaphragm ring by sliding the radially outer platform portions of the plurality of static blade units into the blade unit retaining features in the inner circumference of the segments of the radially outer diaphragm ring, each such segment having a plurality of static blade units attached thereto;
(b) attaching the segments of the radially inner diaphragm ring to the radially inner platform portions of the plurality of static blade units, the plurality of the static blade units attached to the segments of the radially outer diaphragm ring, by sliding the blade unit retaining means of the radially inner diaphragm ring onto the radially inner platform portions of the plurality of static blade units, the segments of the radially outer diaphragm ring having the plurality of static blade units and at least one segment of the radially inner diaphragm ring attached thereto; and
(c) completing assembly of the axial flow turbine diaphragm by joining together the separate segments of the radially outer diaphragm ring with the plurality of static blade units and the segments of the radially inner diaphragm ring attached thereto.

16. The axial flow turbine diaphragm according to claim 1 , in which the radially outer platform portions of the plurality of static blade units and/or the blade unit retaining features of the radially outer diaphragm ring are provided with stop features operative against movement of the radially outer platform portions relative to the blade unit retaining features of the radially outer diaphragm ring under the influence of a pr

Assignees

• Alstom Technology Ltd
• General Electric Technology Gmbh

Inventors

• Brummitt-Brown Angus Robert
• Mistry Kanu
• Lord Adrian Clifford

Classifications

• F05D2240/80

  Platforms for stationary or moving blades · CPC title

• F05D2250/314

  the axes being inclined in relation to each other · CPC title

• F01D25/246

  Fastening of diaphragms or stator-rings · CPC title

• F05D2220/31

  in steam turbines · CPC title

• F01D9/042 Primary

  fixing blades to stators (fixing stator-rings in the casing or to each other F01D25/246) · CPC title