Turbine exhaust hood

Patent metadata

Field	Value
Publication number	US-10989074-B2
Application number	US-201815860133-A
Country	US
Kind code	B2
Filing date	Jan 2, 2018
Priority date	Jan 17, 2017
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

An exhaust hood in an embodiment includes: an outer casing; and an annular diffuser which is provided on a downstream side of a final turbine stage and formed by a cylindrical steam guide and a cylindrical bearing cone provided inside the steam guide. The steam guide includes a curved guide and a flat-plate guide which is provided on a downstream side of the curved guide. When a cross section of the outer casing vertical to the rotation axis of the turbine rotor is viewed from the downstream side of the steam guide, expansion outward in the radial direction of the flat-plate guide is set based on D/H where a distance between the rotation axis of the turbine rotor and an inner surface of the outer casing is H and a distance between the rotation axis of the turbine rotor and a downstream end of the flat-plate guide is D.

First claim

What is claimed is:

1. A method for designing a turbine exhaust hood of a low-pressure turbine through which a working fluid flowing out of a turbine stage at a final stage of an axial flow turbine including a turbine rotor passes, the method comprising:
constituting the turbine exhaust hood by a casing;
providing an annular diffuser on a first downstream side of the turbine stage at the final stage, the annular diffuser being formed by a cylindrical guide and a cylindrical cone provided inside the cylindrical guide to discharge the working fluid passing through rotor blades of the turbine stage at the final stage outward in a radial direction, the cylindrical guide having a curved guide and a flat-plate guide provided on a second downstream side of the curved guide and vertical to a direction of a rotation axis of the turbine rotor, the curved guide being curved outward in the radial direction as going downstream, the flat-plate guide expanding outward in the radial direction;
when a cross section of the casing vertical to the rotation axis of the turbine rotor is viewed from the downstream side of the cylindrical guide, setting expansion outward in the radial direction of the flat-plate guide based on D/H such that setting the expansion outward in the radial direction of the flat-plate guide based on D/H is independent of the operating conditions and the blade length of the rotor blades at the final turbine stage where a first distance between the rotation axis of the turbine rotor and an inner surface of the casing is H and a second distance between the rotation axis of the turbine rotor and a downstream end of the flat-plate guide is D, and the D/H satisfies a following relational expression in a same radial direction:
0.6≤ D/H≤ 0.8.

2. The method according to claim 1 , further comprising:
including in the casing, an arc-shaped casing curved in a shape of protruding outward, and a box-shaped casing connected to the arc-shaped casing; and
on an arc-shaped casing side including two virtual straight lines each linking each of two connection points between the arc-shaped casing and the box-shaped casing and the rotation axis of the turbine rotor, the H being the first distance between the rotation axis of the turbine rotor and the inner surface of the arc-shaped casing.

3. The method according to claim 2 , further comprising:
locating the two virtual straight lines on a same straight line passing through the rotation axis of the turbine rotor.

4. The method according to claim 2 , further comprising:
extending the two virtual straight lines inclined to the arc-shaped casing side from the rotation axis of the turbine rotor.

5. The method according to claim 2 , further comprising:
extending the virtual straight lines inclined to a box-shaped casing side from the rotation axis of the turbine rotor.

6. The method according to claim 1 , the expansion outward in the radial direction of the flat-plate guide is non-uniform in a circumferential direction with respect to the rotation axis of the turbine rotor.

Assignees

• Toshiba Kk
• Toshiba Energy Systems & Solutions Corp

Inventors

• Mitsui Hiroaki
• Tashima Tsuguhisa
• Iwai Shogo
• Ono Takahiro
• Fukabori Daichi

Classifications

• F05D2250/71

  curved · CPC title

• F05D2240/14

  Casings or housings protecting or supporting assemblies within · CPC title

• F05D2220/31

  in steam turbines · CPC title

• F05D2250/52

  Outlet · CPC title

• F01D25/30 Primary

  Exhaust heads, chambers, or the like · CPC title