Inner casing for steam turbine engine

Patent metadata

Field	Value
Publication number	US-10094245-B2
Application number	US-201313886204-A
Country	US
Kind code	B2
Filing date	May 2, 2013
Priority date	Jan 23, 2013
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

A system includes a steam turbine. The steam turbine includes an outer casing and an inner casing disposed within the outer casing. The inner casing is horizontally split in an axial direction into an upper inner casing portion and a lower inner casing portion. The steam turbine also includes an impulse stage disposed within the inner casing, wherein the inner casing is configured to provide full arc admission of a fluid to the impulse stage. The steam turbine further includes at least one reaction stage having multiple blades. The at least one reaction stage is integrated within the inner casing.

First claim

The invention claimed is:

1. A system, comprising:
a steam turbine comprising:
an outer casing;
an inner casing disposed within the outer casing, wherein the inner casing is horizontally split in an axial direction into an upper inner casing portion and a lower inner casing portion, wherein the inner casing a retainer includes a retainer that interfaces with a portion of the outer casing to block movement of the inner casing relative to the outer casing in response to an axial force generated during operation of the steam turbine, and a flange comprising an upper flange portion and a lower flange portion, wherein the retainer comprises, an upper retainer portion that only partially extends circumferentially relative to a rotational axis of the steam turbine about a first outer surface of the upper inner casing portion, and a lower retainer portion that only partially extends circumferentially relative to the rotational axis about a second outer surface of the lower inner casing portion, and wherein the upper retainer portion and the lower retainer portion are located at a same axial location relative to the rotational axis, the upper retainer portion and the lower retainer portion form gaps extending circumferentially between terminal ends of the upper retainer portion and the lower retainer portion relative to the rotational axis at the same axial location between the outer casing, and the inner casing, and the retainer extends circumferentially relative to the rotational axis about an outer perimeter of the inner casing at the same axial location;
a first cavity radially disposed between the outer casing and the inner casing upstream of the retainer;
a second cavity radially disposed between the outer casing and the inner casing downstream of the retainer, wherein the first cavity is fluidly coupled to the second cavity via the gaps;
an impulse stage disposed within the inner casing, wherein the inner casing is configured to provide full arc admission of a fluid to the impulse stage;
at least one reaction stage comprising a plurality of blades, wherein the at least one reaction stage is integrated within the inner casing, and the retainer is disposed about the at least one reaction stage at the same axial location; and
at least one steam duct comprising an upper stream duct portion disposed in the upper inner casing portion and a lower steam duct portion disposed in the lower inner casing portion configured to form a sealed interface between the upper and lower flange portions to block leakage of fluid through the sealed interface, the sealed interface comprising an annular seal ring and an anti-rotation mechanism disposed through a portion of the annular seal ring to block rotation of the annular seal ring relative to the upper and lower steam duct portions.

2. The system of claim 1 , wherein the impulse stage is disposed within the inner casing upstream of the at least one reaction stage.

3. The system of claim 1 , wherein the inner casing comprises a plurality of steam ducts that define a fluid flow path through the upper and lower inner casing portions, and the fluid flow path is configured to provide full arc admission of the fluid to the impulse stage via the fluid flow path.

4. The system of claim 1 , wherein the flange is horizontally split in the axial direction.

5. The system of claim 1 , wherein the sealed interface comprises a first annular groove disposed within a first end of the upper steam duct portion and a second annular groove disposed within a second end of the lower steam duct portion and vertically aligned with the first annular groove, and wherein the annular seal ring is disposed between the upper and lower steam duct portions within the first and second annular grooves so that the first and second annular grooves when the first end abuts the second end enclose the annular seal ring within the first and second ends and the annular seal ring directly contacts both the upper and lower steam duct portions.

6. The system of claim 1 , wherein the upper and lower retainer portions each form a groove configured to receive respective portions of the outer casing.

7. A system, comprising:
a steam turbine inner casing configured to be disposed within an outer casing of a steam turbine, wherein the steam turbine inner casing is horizontally split in an axial direction into an upper inner casing portion having an upper flange portion and a lower inner casing portion having a lower flange portion, the upper and lower flange portions forming a horizontally split flange, the steam turbine inner casing is configured to be disposed about an impulse stage and to provide full arc admission of a fluid to the impulse stage, and the steam turbine inner casing is configured to be integrated with and disposed about at least one reaction stage having a plurality of blades, and wherein the steam turbine inner casing comprises a plurality of steam ducts that define a fluid flow path through the upper and lower inner casing portions, and the fluid flow path is configured to provide full arc admission of a fluid to the impulse stage via the fluid flow path, and wherein at least one steam duct of the plurality of steam ducts comprises an upper steam duct portion disposed in the upper inner casing portion and a lower steam duct portion disposed in the lower inner casing portion, and the upper steam duct portion and the lower steam duct portion form a sealed interface between the upper and lower flange portions to block leakage of fluid through the sealed interface, and wherein the sealed interface comprises a first annular groove disposed within a first end of the upper steam duct portion and a second annular groove disposed within a second end of the lower steam duct portion and vertically aligned with the first annular groove, and the sealed interface comprises an annular seal ring disposed between the upper and lower steam duct portions within the first and second annular grooves so that the first and second annular grooves when the first end abuts the second end enclose the annular seal ring within the first and second ends and the annular seal ring directly contacts both the upper and lower steam duct portions, wherein the sealed interface comprises an anti-rotation mechanism disposed through a portion of the annular seal ring to block rotation of the annular seal ring relative to the upper and lower steam duct portions.

8. The system of claim 7 , wherein the steam turbine inner casing is configured to be disposed about the impulse stage upstream of a location of the at least one reaction stage.

9. The system of claim 7 , wherein the inner casing comprises a retainer that interfaces with a portion of the outer casing to block movement of inner casing relative to the outer casing in response to an axial force generated during operation of the steam turbine.

10. The system of claim 9 , wherein the retainer comprises an upper retainer portion that only partially extends circumferentially relative to a rotational axis of the steam turbine about a first outer surface of the upper inner casing portion, and a lower retainer portion that only partially extends circumferentially relative to the rotational axis about a second outer surface of the lower inner casing portion, and wherein the upper retainer portion and the lower retainer portion are located at a same axial location relative to the rotational axis, the upper retainer portion and the lower retainer portion form gaps extending circumferentially between terminal ends of the upper retainer portion and the lower retainer portion relative to the rotational axis at the same axial location, and the retainer extends circumferentially relative to the rotational axis about an outer perim

Assignees

• Nuovo Pignone Srl

Inventors

• Imparato Enzo
• Grilli Marco
• Giusti Enrico

Classifications

• F01D1/16 Primary

  characterised by having both reaction stages and impulse stages · CPC title

• F01D9/04

  forming ring or sector · CPC title

• F01D17/18

  varying effective number of nozzles or guide conduits {, e.g. sequentially operable valves for steam turbines} · CPC title

• F01D1/023

  the working-fluid being divided into several separate flows (F01D3/02 takes precedence); several separate fluid flows being united in a single flow; the machine or engine having provision for two or more different possible fluid flow paths · CPC title

• F05D2220/31

  in steam turbines · CPC title