US2276695A - Steam turbine - Google Patents

Description

March 17, 194 2 E. LAVARELLCS 2,276,695

STEAM TURBINE Filed Feb. 25. 1939 2 {if 2 I 24 at 111m 20 2 7 5 40 7 H 8 6 6 g i} i 9 i 2. i l I h H p i 3 324245 45 I o 35 we. El .1.

2o 1 5 1 21 L. H 8 40 i i 6 ii: i" 6 7 i M ERNESTO LAVARELLJO .g gg g WW I Patented Mar. 17, 1942 stares rarest or ies v STEAM TURBINE Ernesto Lavarello, Genoa, Italy application February 25, 1939, Serial'No. 258,352

7 Claims. (El. 253-165) The present invention refers to steam turbines in which not only the rotor but the element corresponding to the usual stator also rotates.

In known steam turbines (action turbine, reaction turbine, combined impulse and reaction turbine etc.) the outer casing is fixed and'carries towards the interior the nozzles and the guideblades, while the inner rotating element or rotor is fitted with moving blades hereinafter referred to as receiving blades. It is also known that usually the velocity of rotation of the inner element which carries the receiving blades, must be limited to a maximum value, for instance to a value such as to give a peripheral velocity of about 180 metres per second, because otherwise the centrifugal force exerted on the blades which are connected to the rotor is such as to endanger the rigid connection of the blades to the rotating element.

The impossibility of increasing said velocity of rotation causes the disadvantage that the efliciency of the turbine is lowered; moreover, the fact that the nozzles and the distributing blades are fixed causes the disadvantages of greater weight, larger dimensions, and higher cost of the turbine.

The present invention eliminates the aforesaid disadvantages owing to the fact that the turbine has two elements rotating in opposite directions, one element being hollow and carrying th nozzles and the guide-blades, while the other element is rotatable within the first element and carries the receiving blades; thus while the latter or in ner element which carries blades externally can be rotated up to said angular velocity,'which corresponds to a peripheral velocity of about 180 metres per second, the other hollow element which carries blades inwardly is not submitted to any dangerous condition of working, and cooperates in its turn to provide the most intensive utilization of the energy of the steam.

Other features of the invention will appear from the following description of two embodiments of the invention given only by way of example, with reference to the accompanying drawing, in which Figure 1 shows an axial section of a turbine made according to the invention, and arranged to have the steam travel in parallel paths past two sets of blades toward a common steam outlet chamber; while Figure 2 is also an axial section of a turbine likewise made according to the invention, but arranged to have the steam travel past the two sets of blades in series.

In thesefigures, the same references-indicate the same or like parts.

Referring particularly tdFigure 1, the steam is introduced in the directionof arrow J in the chamber I of the turbine, and feeds nozzles 2 carried by the fixed outer casing 3 and also nozzles t carried by'a rotating disc'5 ofthe unit or hollow rotating member which is constituted by saiddisc member 5 by a disc member 2! and by a ring 35 which connects the discs 5 and 21. The discs 5 and 2| are mounted by means of keys 5 on tubular shafts-1 which are supported by a central shaft 8011 which by means of a key 9 is mounted a rotating element or wheel 10. A gear H is mounted at one extremity of one of the tubular shafts I.

The steam which has'passe'd through the-nozzles 2 passes to the first row of receiving blades [2, externally of ring 35 and, continuing its course, acts on the guide-blades .l'3 carried'by the outer casing 3 and then on the receiving blades l4 carried by ring 35 and so on until it reaches the chamber 15, from which it is discharged in the direction of arrow l6. Similarly, the steam which has penetrated chamber I, after flowing through nozzles 4, drives the receiving blades I! mounted on the rotating wheel l0, then the guideblades I8 inwardly mounted on the ring 35, and then the receiving blades i9 mounted on the wheel Ill and so on until the steam passes through the openings 20 provided on disc 21 into the chamber [5 where it mixes with the steam from the nozzles 2 and is discharged in the direction of arrow It. I

From the foregoing description it will be understood that the casing 3 is fixed, and that the assembly forming the hollow rotatable member comprising the parts 5, 35 and 2!, togetherwith the blades mounted on the ring 35, thetubular shaft 1 and gear H, rotates in one direction, while the wheel or rotating element It, with the blades fixed on it and shaft 8 rotates in an opposite direction, so that the energy of the steam is exploited simultaneously by two elements, resulting in a higher efiiciency for'the turbine, less weight, smaller dimensions, and lower cost of same.

However, in this form of turbine, means may well be included for increasing the power of the turbine. Thus, a supporting member 29 secured to the left side 'of disc 5 carries receiving blades 30, while an annular member 3| is secured to the casing wall and provided with a nozzle 32 and also carrying guide blades 33, so that steam from said nozzle will alternately act on a receiving blade 30 and then on a guide blade 33 and so on. The net result is that the power produced by these blades as they are acted on by the steam will be added to the power already applied to the rotor consisting of discs 5 and 2| and ring member 35.

The drawing also shows other features which include the construction of the turbine supports, labyrinth, etc.

Referring now to Figure 2 the steam enters in the direction of arrow .f; flows through the -ad mission chamber 22, through the nozzles 4 carried by the rotating disc 5, and then acts on the receiving blades 11 of the wheel I0, on the guideblades l8 of the ring 35, on the receiving blades IQ of wheel l0 and so on, until it passes through holes into chamber 23. Here the steam travels in the direction of the arrow 24 and is caused to pass through the direction nozzles 25 carried by the casing 3; it then acts successively on the As the present invention has been based on what has been described above and illustrated, many variations and additions can be made in carrying the invention into effect. Thus it is to be noted that there are two elements, the first one comprising discs 5 and 2| and ring which u connected them, and the other one comprising wheel I 0. The guide elements, i. e. nozzles and guide-blades according to the embodiment, may be fitted externally of the wheel l0, internally or externally of ring 35; the same applies to the receiving blades.

Having now fully described my invention, I claim:

1. In an axial flow steam turbine having an exterior fixed casing and within the same a rotating element or wheel mounted upon a shaft so as to be rotatable within said casing, said rotating element'having at least two rows of receiving blades'projecting outwardly from the periphery thereof, and there being a steam-inlet port and an outlet port in said fixed casing, the combination of a hollow rotatable member surrounding said rotating element and having upon the interior thereof at least one row of guide blades projecting inwardly between said rows of receiving blades so as to cooperate therewith, said hollow member being rotatably mounted on said shaft and having nozzles in one side for directing jets of steam against said blades and outlet apertures on the other side allowing steam to escape from said blades, a plurality of rows of receiving blades projecting from the exterior of said hollow member, at least one corresponding row of stationary guide blades projecting in between said last mentioned receiving blades from the fixed casing, there being stationary nozzles fixed in said casing for directing jets of steam from one side against said stationary guide blades and the corresponding receiving blades,

and sealing means including a blade support projecting blade support and carrying a plurality of fixed guide blades cooperating with said receiving blades on the latter, said rigid annular blade supporting member also having a plurality of fixed nozzles disposed adjacent to said last mentioned receiving blades in positions effective to direct jets of steam against said latter receiving blades and the corresponding guide blades, in order to effect a maximum exhaustion of the energy from the steam used in said turbine.

2. An axial fiow steam turbine according to claim 1, wherein the hollow-rotatable member includes a pair of co-axial spaced disc members and a ring connecting said disc members, while the nozzles of said hollow member are disposed in one of said disc members and the outlet apertures of said hollow member are disposed in the other disc member.

3. An axial flow steam turbine according to claim 1, wherein the nozzles in the rigid annular blade supporting member are directed in opposite directions with respect to the directions in which the other nozzles are disposed.

4. An axial flow steam turbine according to claim 1, wherein the-dimensions and mutual locations and spacing of the nozzles and blades as well as the blade supporting members together forming the sealing means are all proportioned to be suificient and efiective to balance the axial thrust of the turbine when in operation.

5. An axial flow steam turbine according to claim 1, wherein the blade support projecting from one side of the hollow rotatable member has a portion, between the point of attachment to said member and the blades, which is spaced from said one side of said hollow member so as to 'form a rotating chamber which rotates with said hollow member, and wherein the nozzles in the latter member are located in the same side from which the blade support projects and disposed adjacent the bottom or deepest portion of said rotating chamber toward the shaft of the turbine in order to cause the steam entering said latter chamber to rotate and enter said nozzles free from any lamination or layer effects.

6. An axial flow steam turbine according to claim 1, wherein the receiving blades upon the hollow rotatable member project from the periphery thereof and the corresponding stationary guide blades in the casing project inwardly from the interior of its periphery while the casing has a steam chamber in one side and both said casing and said hollow rotatable member have their nozzles disposed at the same side so as to be fed simultaneously with steam from said chamber, and wherein the casing has a second steam chamber in the other side which is open directly to the receiving blades upon the periphery of the hollow rotatable member while the outlet apertures in the latter member open into said second steam chamber, so that steam from the blades within and without said hollow rotatable member pass in parallel paths from two sets of nozzles past two sets of blades toward said second steam chamber.

7. An axial flow steam turbine according to claim 1, wherein the receiving blades upon the hollow rotatable member project from the periphery thereof and the corresponding stationary guide blades in the casing project inwardly from the interior of its periphery while the casing has a steam supply chamber in the side corresponding to the side of the hollow rotatable member in which the nozzles of the latter are disposed so as to feed steam thereto from said steam supply chamber, there being a separate steam outlet chamber in the same side of said casing in which the hollow rotatable member is provided with its nozzles directly open to the exterior receiving blades upon the periphery of said hollow rotatable member, and wherein the casing has a further steam chamber in the other side with the nozzles in said casing disposed at the same side between said further steam cham her and said. exterior blades on the periphery of the hollow rotatable member, while the outlet apertures in the latter member open into said further steam chamber, so that the steam will pass through two sets of nozzles and blades in series within the turbine.

ERNESTO LAVARELLO.

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