US3724967A

US3724967A - Moisture removal device for a steam turbine

Info

Publication number: US3724967A
Application number: US00193345A
Authority: US
Inventors: F Fischer
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1971-10-28
Filing date: 1971-10-28
Publication date: 1973-04-03
Anticipated expiration: 1990-04-03
Also published as: IT970011B

Abstract

A row of stationary blades of the steam turbine having interconnecting cavities in the base portions thereof to form an annular chamber which cooperates with inlet and outlet ports disposed adjacent the trailing edges of these blades and adjacent the casing and rotor respectively to remove water and steam from the stationary blades, to separate the water and steam, and to direct the steam toward an adjacent row of rotating blades and the water to a drain.

Description

United States Patent v 1191 Fischer [54] MOISTURE REMOVAL DEVICE FOR A STEAM TURBINE Y [75] Inventor: Frederick K. Fischer, Wawa, Pa. [73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa. [22] Filed: Oct. 28, 1971 211 Appl. No.: 193,345

52 US. Cl AIS/168, 415/010. 1 [51] Int. Cl. ..F0ld 25/32, FOld 15/00 [58] Field of Search ..4l5/DIG. 1,121 A, 168

[56] References Cited UNITED STATES PATENTS 741,776 10/1903 Dodge ..4l5/l68 2,lll,878 3/1938 Tongeren. ..4l5/l68 2,332,322 10/1943 Kraft ..4l5/l68 2,362,831 11/1944 Kraft. ..4l5/l68 2,399,009 4/1946 Doran ..415/l68 1/1967 Wood ..4l5/168 Primary Examiner-Henry F. Raduazo Attorney-A. T. Stratton et al.

ABSTRACT A row of stationary blades of the steam turbine having interconnecting cavities in the base portions thereof to form an annular chamber which cooperates with inlet and outlet ports disposed adjacent the trailing edges of these blades and adjacent the casing and rotor respectively to remove water and steam from the stationary blades, to separate the water and steam, and to direct the steam toward an adjacent row of rotating blades and the water to a drain.

'8 Claims, 2 Drawing Figures MOISTURE REMOVAL DEVICE FOR A STEAM TURBINE BACKGROUND OF THE INVENTION Since the tips of the leading edges of low pressure rotating blades are theprirnary erosion areas, it is a common practice to coator form the tips of these, blades with a hard erosion resistant material, such as Stellite. However, providing the erosion resistant lead-- encircling the rotor 3, an annular array of circumferentially spaced rotatable blades 7 fastened to the rotor 3, an annular array of circumferentially spaced stationary blades or nozzles 9 fastened to the casing and a device 11 disposed in the stationary blades 9 for removing water and steam from the motive steam as the water passes over the stationary blades, separating the steam from the water, returning the steam to perform additional work on the rotating blades 7 and directing the water to a drain 12.

Motive steam flows through the

blades

7 and 9 from left to right, as shown in the drawings, and the

blades

7 and 9 have a general air foil shaped cross section with the leading edges 13 and 14 on the left and the

trailing edges

15 and 16 on the right.

As shown in FIG. 1, the device 11 comprises an inlet or first port 17 disposed adjacent the casing 5 and trailing edge 15 of the stationary blades 9, an outlet or second port 19 disposed adjacent the rotor 3 and trailing edge 15 of the stationary blade 9, and a chamber 21 ing edge on the rotating blades is expensive and may and the stationary blades .will increase the velocity of the water droplets and reduce the impact velocity of the water droplets as they impinge on the rotating blades to reduce erosion. However, this increases the turbine length, weight, and cost.

SUMMARY OF THE INVENTION In general, a turbine operated by motive steam, when made in accordance withthis invention, has a rotor, a casing encircling the rotor, an annular array of circumferentially spaced rotatable blades, an annular array of 'circumferentially spaced stationary blades, a condensate drain and a device disposed in the stationary blades for removing water and steam from the motive placed in communication with the ports 17 and 19 by steam, separating the steam and water, returning the steam to perform additional work on the rotating blades, and directing the water to the drain.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in detail, FIGS. and 2 show a steam turbine 1 having a rotor 3, a casing 5 respectively, The

ducts

23 and 25 terminate in the chamber 21' and have short nozzles 27 and 29, respectively, which extend into the chamber 21 to prevent reentrainment of the water and steam which separate due to a reduction in the velocity of the mixture entering the chamber 21. Water separated from the mixture flows by gravity to the drain 12 and moisture-free steam flows to the outlet port 19 as a result of the difference in pressure between the inlet and outlet ports 17 and 19, resulting from their respective locations and the higher pressures which are created adjacent the casing due to the centrifugal forces acting on the motive steam. The same forces cause the moisture or water in the steam to be spun outwardly toward the cas- The arrangement of the

ducts

23 and 25 shown in FIG. 1 is such that there will be essentially no reentrainment of water droplets in the steam flowing through the discharge duct 25 irrespective of the radial orientation of the stationary blades.

The annular chamber 21 is formed from interconriecting, registering cavities 29 in the base portions of the stationary blades 9. If required, peripheral seals or gaskets may be disposed between adjacent base portions to form a seal around the cavity to produce the annular sealed chamber 21.

FIG. 2 shows a modification, wherein the annular chamber 21 has an outer compartment 31 and an inner compartment 33. The inlet port 17 is brought into direct communication with the outer compartment 31 by the inlet duct 23 and the outlet port 19 is brought in direct communication with the inner compartment 33 by the outlet duct 25. Walls 35, separating the inner compartment 33 from the outer compartment 31, have a plurality of opening 37, which allow steam to flow freely from the outer to the inner compartment. The outer compartment 31 has a larger volume than the inner compartment 33, so as to allow the steam and water mixture entering through the inlet ports 17 and ducts 23 to slow down so that the water separates from the steam. The water then flows by gravity to the drain 12, while the steam flows into the inner compartment 33 and out the outlet ducts 25 and ports 19. The inlet and outlet ducts 17 and 19 may be disposed to cooperate with the inner and outer compartments 31 and 33 to foster centrifugal separation of the mixture of steam and water and thereby effectuate more complete separation.

The stationary blades with cooperatively associated chambers, ports, and ducts, hereinbefore described advantageously extract some steam with the moisture, which greatly enhances the effectiveness of the moisture removal from the blades and by separating the moisture from the steam and returning the steam to the main steam flow to perform additional work on the downstream rotating blade provides optimum moisture removal with a minimum loss of motive steam.

What is claimed is:

1. A turbine operated by motive steam and having a rotor, a casing encircling said rotor, an annular array of circumferentially spaced rotatable blades, an annular array of circumferentially spaced stationary blades, a condensate drain, and means disposed in said stationary blades for removing water and steam from the motive steam, separating the steam and water, returning the steam to perform additional work on the rotatable blades, and directing the water to the drain.

2. A turbine as set forth in claim 1, wherein the blades have a general air foil shaped cross section with leading and trailing edges and the removal and separating means comprises a first port disposed adjacent the trailing edge of the stationary blade and the casing, a second port disposed adjacent the rotor, and a chamber in communication with said ports, said chamber being sufficiently large to reduce the velocity of the steam and water mixture entering through the first port to cause separation thereof and the second port being disposed to allow steam to flow from said chamber to rejoin the motive steam.

3. A turbine as set forth in claim 2, wherein the second port is disposed adjacent the trailing edge of the stationary blade.

4. A turbine as set forth in claim 2, wherein interconnecting cavities in the stationary blades register to form the chamber.

5. A turbine as set forth in claim 2, wherein the first port communicates with said chamber through a first duct and. the second port communicates with said chamber through a second duct and said first and second ducts are so disposed with respect to the chamber that they cooperate with the chamber to provide separation of water and steam irrespective of the radial orientation of the stationary blades.

6. A turbine as set forth in claim 2, wherein the chamber comprises an inner compartment and an outer compartment there being a variety of openings between said compartments and the first port is in direct communication with said outer compartment and the second port is in direct communication with the inner compartment.

7. A turbine as set forth in claim 5, wherein the inner compartments register to form an inner annular chamber and the outer compartments register to form an outer annular chamber containing said inner annular chamber.

8. A turbine as set forth in claim 7, wherein the volume of the inner annular chamber is less than the volume of the outer annular chamber.

at a: 4 a t

Claims

5. A turbine as set forth in claim 2, wherein the first port communicates with said chamber through a first duct and the second port communicates with said chamber through a second duct and said first and second ducts are so disposed with respect to the chamber that they cooperate with the chamber to provide separation of water and steam irrespective of the radial orientation of the stationary blades.