US2111878A

US2111878A - Means for draining moisture from steam in steam turbines

Info

Publication number: US2111878A
Application number: US87566A
Authority: US
Inventors: Hermannus Van Tongeren
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-07-02
Filing date: 1936-06-26
Publication date: 1938-03-22
Anticipated expiration: 1955-03-22

Description

March .22, 1938. H. VAN TONGEREN ,1 3

MEANS FOR DRAINING MOISTURE FROM STEAM IN STEAM TURBINES Filed June 26, 1956 FIGS FIE-3.4

Patented Mar. 22, 1938 UNITED STATES MEANS FOR DRAINING MOISTURE FRQM STEAM IN STEAM TURBINES Hermannus van Tongeren, Heemstede, Netherlands 7 Application June 26,

1936, Serial No. 87,566

In the Netherlands July 2, 1935 3 Claims.

This invention relates to means for draining moisture from steam in steam turbines.

It is well known that in steam turbines, and especially in the low pressure stages thereof, part of the steam is condensed and that the water of condensation thus formed has a deteriorating action on the blades. The principal object of my invention is an improved construction whereby the water droplets, which are thrown by centrifugal force from the rotor or rotors, are collected--and thereafter discharged from the oas ing-in such a manner that they cannot possibly return into the blading.

With this object in view, I suggest to provide a circumferential groovein the inner wall of the casing, said groove being so disposed relative to the corresponding rotor that the droplets thrown radially outwards from the rotor can reach the body of water already present in the groove without contacting with any stationary part of the turbine. Since the body of water in the groove, owing to the impacts of the droplets thrown thereinto, has a circumferential speed not essentially smaller than that of the droplets, the latter will be caught thereby without considerable rebounding. It will easily be understood that such a gyrating mass of water surrounding the rotor is much better adapted to catch and hold the droplets than are stationary solid walls.

In order thatmy invention may be more fully understood by those skilled in the art, I shall now proceed to describe the same in further detail with reference to the annexed drawing, in which:

Fig. 1 is part of an axial section of an axial flow turbine,

Fig. 2 shows part of a cross-sectional view of said turbine, along the line II--II in Fig. 1,

Figs. 3, 4 and 5 illustrate parts of axial sections along the lines III--I1'I, IVIV and VV, respectively, in Fig. 2,

Fig. 6 shows a modification as part of an axial section of another axial flow turbine,

Fig. 7 is part of a cross-sectional view of said turbine, along the line VIIVII in Fig. 6, and

Figs. 8, 9 and 10 are parts of axial sections along the lines VIIIVIII, IX--IX and X--X, respectively, in Fig. 7.

InFigs. 1-5, a rotary blade wheel is designated by I, the turbine casing by 2. The numerals 3 and 4 indicate normally shaped fixed guide blade rims on either side of wheel I. The butt strap or sealing ring 5 of the moving blades is provided, on the right hand side, i. e. on the outlet side, with a drip rim or edge 6, from which the water droplets are radially thrown off. Surrounding said drip rim, the inner face of easing 2 has a circumferential collecting groove I machined therein. As shown, the depth of said groove is greatest in the radial plane passing through the drip rim, i. e. on the outlet side of the moving blades, and gradually decreases towards the radial plane passing through the inlet side of said blades. Through a small portion of the circumference, the sloping side wall of the groove 1 is recessed so as to form a sill II] located at a somewhat smaller distance from the turbine axis than the bottom of the groove. Secured to said sill as by screws 8a is a nozzle 8 fitted at the inner end of a passage 9 provided in the wall of the casing 2 and serving to discharge water collecting in the groove.

When the turbine is in operation, the groove I will after a certain period of time be filled with a gyrating, annular body of water, the more or less cylindrical inner surface of which will be substantially flush with the sill Ill. Any water flowing over said sill will be forced by its kinetic energy into the nozzle 8 and thus be discharged through the passage 9.

Figs. 3, 4 and 5 clearly show that any droplet thrown radially off the drip rim 6 will reach the level of the gyrating body of water in groove 1 and thus be caught and held by said water, with out coming into contact with the radial right hand side wall of said groove or with any other stationary part of the casing.

It is not necessary to provide every rotor element traversed by more or less wet steam with a draining device as described. For instance, a group of rotor elements or blade wheels, only the last wheel on the outlet side of such group to gether with the part of the casing surrounding such wheel may be provided with a draining device.

Figs. 6-10 of the drawing illustrate another embodiment of my invention, wherein the butt strap II is provided with two drip rims I2 and I3 on the inlet and on the outlet side, respectively. Said drip rims are surrounded by water collecting grooves I4 and I5, respectively, machined in the turbine casing 2. Also in this case the depth of each groove is greatest in the radial plane of the corresponding drip rim. The grooves are separated from one another by an annular ridge I6, which through a small portion of its length is recessed to form a sill II, to which the nozzle 8 of the discharge passage 9 is secured by screws 8a.

Secured to the inner face of the ridge I6 is a flat ring l8, the side edges of which are suitably spaced from the opposite radial walls of the grooves 14 and I5, respectively, so that any droplets thrown from the drip rims I2, I3 can freely pass through the narrow slots thus formed without coming into contact with said walls.

The strap l8 acts as a shield or baffie having for its effect greatly to reduce the circumferential speed of the steam carried along by the butt strap I I. Owing thereto, the levels of the bodies of water in the grooves I4, l5 are not seriously disturbed by wave motion.

What I claim is:

1. In a steam turbine, a casing, a rotor element provided with a radially directed drip rim, a circumferential water-collecting groove in the inner wall of the casing situated in radial alignment of said drip rim and with its bottom spaced from said rim and a water-discharging conduit opening into said groove substantially level with said drip rim, the groove being so disposed and formed as to permit water droplets thrown by centrifugal force from said drip rim to collect in said groove thus providing an annular body of water and to prevent said droplets from being thrown into direct contact with any stationary solid Wall.

2. In a steam turbine, a casing, a rotor element provided with a radially directed drip rim, a circumferential water-collecting groove in the inner wall of the casing situated in radial alignment of said drip rim and with its bottom spaced from said rim and a water-discharging conduit opening into said groove substantially level with said drip rim, the groove being so disposed and formed as to permit Water droplets thrown by centrifugal force from said drip rim to collect in said groove thus providing an annular body of Water and to prevent said droplets from being thrown into direct contact with any stationary solid wall, and an annular bafile secured to the casing partly closing said groove leaving only a narrow circumferential slot in the radial plane of said drip rim.

3. In a steam turbine, a casing, a rotor element provided with a drip rim at its inlet and outlet sides, a circumferential water-collecting groove in the inner wall of the casing opposite the inlet and outlet sides of said rotor element and in radial alignment with the respective drip rims, a circumferential ridge intermediate of said grooves, a recess in said ridge forming a sill and a Water-discharging conduit opening in said sill substantially level with the drip rims, the grooves being so dispose-d and formed as to permit water droplets thrown by centrifugal force from the respective rims to collect in the respective grooves thus providing annular bodies of water in the bottoms of the grooves, said droplets not coming in direct contact with any stationary solid wall.

HERMANNUS VAN TONGEREN.