US1211682A - Steam-turbine. - Google Patents

Description

C. G. CURTIS.

STEAM TURBINE.

APPLICATION FILED MAR. 19, 1914.

1 %1 1 8%, Patented Jan. 9,1917.

2 SHEETSSHEET l.

E I 15 T J J6 5; l J9 I 9 E l 6 2i 3 H 1 i 1 :1 i I 1 1; 11 W2 :i l E :3 "Hi i JI 1 J LL, LJLLLL 7| Attorneys.

(In G. CURTIS.

STEAM TURBINE. APPLICATION FILED'MAR. 19.1914. 1,?91 1 6% menm m. 9,1917.

2 SHEETS-SHEET 2.

? Kflnvemfm CHARLES G. CURTIS, OF NEW YORK, N. Y.

STEAM-TURBINE.

Specification of Letters Patent.

Patented Jan. 9, 121?.

Application filed March 19, 1914. Serial No. 825,828.

' bines, of which the following is a specification.

My invention relates to that type of steam turbine which has a drum stage, and is particularly designed to secure as high an efliciency as possible and at the same time to avoid any excess of thrust on the drum head and any excessive end thrust on the shaft.

"In the drawings, in which similar reference characters designate the same parts in all of the figures, two embodiments of the invention are illustrated.

Figure 1 is a longitudinal section of the up er half of an elastic fluid turbine embo ying my invention employing two wheel stages and a drum stage; Fig. 2 is a transverse section on the line 2, 2 of Fig. 1; Fig. 3 is an end view of three segments of one member of the bafiie sleeve; Fig. a is a view similar to Fig. 1 of a modification, the view being taken on the line i, 4 of Fig. 5; and Fig. 5 is a transverse section on the line 5, 5 of Fig. 4.

Referring to Fig. 1, a turbine is illustrated having a high pressure wheel stage 1, an intermediate wheel stage 2, and a low pressure drum 3. These stages are contained within a casing 4:. High pressure steam is admitted to the stage 1 through one or more nozzles 5. A diaphragm 6 is interposed between the wheel stages 1 and 2. If the turbine is constructed without the wheel stage 1, then the head of the casing i will take the place of the diaphragm. The diaphragm carries one or more nozzles 7 for admitting steam to the intermediate stage 2. The buckets of the stage 2 are preferably carried by a wheel attached to the .drum 3, and are also preferably of greater diameter than the drum, as shown. A baffle sleeve 8 is provided in the space between the diaphragm 6 and the forward end of the drum 3, so as to limit or eliminate the thrust of the high pressure steam, which will depend upon the relative diameter of the sleeve and drum.

The drum 3 is provided with a pressure tad which receives th p e sure a 1;

steam as leaks through the baffle sleeve 8. Means are provided for utilizing this leakage steam, by introducing it into the working passage of the drum stage. The pressure of this steam is maintained at the requisite amount to secure the proper end thrust against the reversed pressure head, by admitting it to that portion of the working passage of the drum stage where the steam is of substantially the same pressure.

In Fig. 1, I show the wall of the drum as provided with a series of peripherally disposed ports 11 which constitute a conduit for passage ofthe steam. The location of these ports, relatively to the working steam passage of the drum, is determined by the pressure at which it is desired to maintain the steam which presses on the head 9.

The apparatus is so designed that the propeller thrust, of a marine turbine, in one direction, is counterbalanced or more or less overbalanced to the necessary extent by the turbine thrust, (pressure of the steam on the blades in the working passage), together with the pressure exerted by the leakage steam on the reversed pressure head.

In the embodiment of the invention chosen for illustration, let it'be assumed that there is a pressure of 90 lbs. in stage 1, and a pressure of 70 lbs. in the intermediate stage 2.

The. propeller thrust being known, the ports 11 will be so positioned with reference to the ends of the drum that the steam will escape from the space inside the drum to the steam passage of the drum stage, at a point where the pressure therein is equal to that at which it is desired to maintain the steam inside the drum,-say 30 lbs. At the same time the fluid escaping through the ports will perform useful work in that portion of the steam passage between the ports and the exhaust 10.

In Fig. 1, I show the head 9 placed at the exhaust end. In Figs. 4 and 5, I show the head located at the forward end of the drum and limiting the leakage steam space to that portion of the casing inside the baffle sleeve and between the reversed pressure head 9 and the diaphragm 6. The ports, in this embodiment of the invention are in the baflie sleeve and the leakage steam is conveyed to the steam or working passage of the dr m thro gh pipes 1a 011 th O t ide of the casing, such pipes constitutin a conduit. The pipes are each preferab ly provided with a valve 13, for varying the degree of steam pressure in the leakage space inside the sleeve, so as to regulate the amount of the thrust. When the valves are wide open the pressure Within the leakage steam space and against the reversed pressure head, will be equal to the pressure in that part of the working passage of the drum stage with which the conduit communicates. This pressure may be increased to any degree up to that of the intermediate stage, by closing the valves.

It is desirable to have little or no steam thrust on the drum outside the sleeve, so that as great an amount of pressure as possible may be had on the pressure head, 'because in this way steam can be led into the working passage 0 the drum stage at a higher pressure and therefore at a point Where it can be utilized over a greater extent of the working passage of the drum stage and a greater amount of work extracted therefrom.

In the embodiment chosen for illustration, the baffle sleeve is of the same diameter as the drum. Should the diameter of the sleeve be less than that of the drum, that portion of the drum outside of the sleeve will'be acted on by the steam in the second stage and hence the pressure of leakage steam must be less to produce the same thrust on the reversed pressure head, and therefore the leakage steam must be admitted to the working passage at a point nearer the exhaust.

As shown in Figs. 1, 2 and 3 the baffle sleeve is constructed as follows: To the end of the drum 3' is rigidly secured an annular wall 14.- The diaphragm 6 is provided with an annular recess 15 within which is seated the inturned flange 16 of a rim 17. The interior face of the rim 17 of the baflie sleeve is provided with circumferential ribs 18 and grooves which tend to reduce the leakage and which provide narrow edges to wear ofi readily in case of actual contact.

The parts of the sleeve are so adjusted that there will be the minimum amount of clearance between the ribs 18 and the wall 14. The rim 17 is'composed of segmental sections and when placed in position in the recess 15 the ends of the sections will. be slightly separated. When steam is admitted to the turbine the heat will cause the segments to expand circumferentially, without I distorting the ring. The spaces between the segments will be closed and the ribs 18 and bafiie groove between them will completely encircle the wall 14. The segments may be held in position in any suitable manner, that shown in Figs. 1 and 2 being a face plate 19 secured to the diaphragm and holding the segments in position, but allowing for circumferential expansion of the segments.

The walls of the recess will prevent movement .of the segments radially.

In Figs. 4 and 5 the segments are shown ment thereof. The purpose of this arrangement is to allow the segments to expand without distorting. the alinement of the pipes 12.

The segments 17 of the baflie sleeve I construct of a material having a greater coefficient of expansion than that of the wall 14bronze' for example-while the drum and the wall are of steel. If for any reason the segments 17 come into contact with the wall 14 at any point, the heat generated by the friction will cause the segments 17 to expand away from thewall 14 and clear themselves. The element 17 is composed of the softer material and will wear to size in the event of coming into contact with the wall 14 and failing to separate therefrom.

Between the diaphragm 6 and the shaft 21 I provide a bafiie sleeve 22 to minimize stages, and means for utilizing the energy a of the leakage steam.

2. A steam turbine having, in combination, a drum stage, a wheel stage, a dia- "phragm, an annular wall carried by the drum, and an overhanging rim carried bythe diaphragm, said rim surrounding the wall, whereby if the rim comes in contact with the wall and thereby becomes heated it will expand and free itself.

3. A steam turbine having, in combination, a drum stage, two wheel stages, 2. diaphragm located between the wheel stages, an annular wall carried by the drum, and an overhanging rim carried by the diaphragm, said rim surrounding the wall, whereby if the rim comes in contact with the wall and thereby becomes heated it will expand and free itself.

4. A steam turbine having in combination a drum stage, two wheel stages, a diaphragm located between the wheel stages, an annular wall projecting from an end f the drum,

an adjustable rim projecting from the diaphragm and surrounding the wall, whereby, if the rim contacts with the wall and thereby becomes heated it will expand and free itself.

5. A steam turbine having a drum stage, an annular wall carried by the drum, a diaphragm, said diaphragm having an annular recess therein, a bafiling rim, made in segments, each segment carrying an inturned flange, said flanges lying Within the annular recess and there being spaces normally separating the adjacent ends of the segments, whereby the segments can expand circumferentially and still retain a circular shape.

, 6. A steamturbine having a dnum stage, an annular wall carried by the drum, a diaphragm, said diaphragm having an annular recess therein, a bailiing rim made in segments, each segment carrying an inturned flange, said flanges lying within the annular recess and there being spaces normally sepa rating the adjacent ends of the segments, whereby the segments can expand circumferentially and still retain a circular shape, said bafiling rinm overhanging the annular wall, whereby if the rim comes in contact with the wall and thereby becomes heated it will expand and free itself.

7. A steam turbine having a high pressurestage and a low pressure drum stage, a diaphragm between the stages, means for permitting leakage between the stages, and means for utilizing the energy of the leakage steam.

This specification signed and witnessed this 18th day of March, 1914.

CHARLES G. CURTIS.

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