US1897989A - Tightening device for radial flow steam turbines - Google Patents

Description

Fe). 14,1933. A: LYSHQLM E 1,897,989

TIGHTENING DEVICE FOR RADIAL FLOW STEAM TURBINES Filed March 14, 1930 mmkwml /f ATTORNEY Patented Feb. 14, 1933 UNITED STATES PATENT oFFicKEvf] A'LF LYSHOLL, OF STOCKHOLM, SWEDEN, ASSIGNOB TO AKTIEIBOLAGET LJ'UNGSTRMS NGTURBIN, OF STOCKHOLM, SWEDEN, A JOINT-STOCK COMPANY OF SWEDEN TIGI-ITENING DEVICE FOR RADIAL FLOW STEAM IU'RBZINES` Application led March Vle, 1930, Serial No. 435,725, and in Germany March 22, 1929.

Radial flow gas or steam turbines have already been designed, in which a plurality of blade rings inserted in between each other each consists of two or several ring bonds hav- 5 ing blades iixed between the bonds.

It has already been proposedto reduce the leakage of the steam passing from the center of the turbine radially through the blade rings under pressure and heat drop, which leakage is caused by lack of tightness between the concentrically arranged blade rings, by means of a radially disposed tightening edge applied to each of the ring bonds. As the development in the technology of steam has 15 led to higher initial pressures of the ylive steam, which has caused certain modifications with respect to the dimensions of the various blades, the tightening devices hitherto known are no longer sucient, and a great portion of 29 the live steam can leak out in passing the various blades, whereby the` efhciencyof the turbine will be reduced.

The present invention relates to turbines of the above described type-and has for a principal object the provision of new and improved tightening means which materiallyre-V duces or eliminates the losses due to leakage. In accordance with one phase of the invention twofor more tightening edges, which individually may be of known type, are arranged on each of one or more of the ring bonds together with means between adjacent tightening edges forV creating turbulence of flow of steam in the direction of leakage. In accordance with another phase of the invention, the number and arrangement of the tightening edges is made different in different pressure stages of the turbine, as will be more fully described in the following description of suit- -0 able embodimentsof the invention, which by way of example are illustrated in the accomp anying drawing forming a part of this specification.

Fig. 1 shows a section through a turbine according to the invention.

Fig. 2 shows a detail of Fig. 1 on a` larger scale.

Fig. 3 shows a modification of a part of the detailed view shown in Fig. 2.

In Fig. 1, the center line of the turbine central space 6 has a tendency to pass not only i through the blade rings 7 a, 7 Z) and 70 but also to leak out through the stuffing boxes 11, the labyrinth packings 12 and between the blade rings, as indicated by the arrow 16. It can be assumed that the same amount of steam` is passing continuously through the various blade rings. If the blade system comprises a great number of blade rings, then the steam leaking out therethrough has to fo-llow a long-` er path with several throttling places, while L if the blade system comprises a less number of blade rings, this path will have less throttling places and be shorter. In previous constructions in which each ring bond only had one' tightening edge, the steam therefore had to pass a certain number of tightening places. As, however, nowadays a blade systemcan be constructed for the sameinitial pressure of the live steam but with aless numberof blade rings, because each blade ring can be produced having a greater radial extension, the steam leaking out has now to pass a less number of tightening places. According to the invention, especially thev intermediate blades 7b are provided withl two tighteningY dges which are more clearly illustrated in igr 2.

Referring to Fig. 2, 13 and 14 designate ring bonds to which `are aiiiXed in vknown manner the blades 15, these parts togetherA constituting a blade ring. Also in this figure there is to be observed the arrow 16 whichindicates the path of the yleaking steam between the blade rings. On each ringbond 13 or 11i are arranged two tightening edges. 17 and 18 extending towardstwo adjacent parts, in this case towards the ring bondof the bladeringwhich lies radially outsidethe former ring. yFliesetightening edges are of known type and united in Vknownfmanner with the ring bonds. In this form of embodiment the tightening edges may be arranged on the outside thereof, seen from the center of the turbine, and they extend then radially towards the ring bond situated on the outside thereof.

According to the invention, two or more tightening edges may, however, also be positioned, as shown in Fig. 3, on that side vof the ring-'bond which is directed towards the center of the turbine and extend then radially towards the ring bond situated on the inside thereof. According to the invention there are, however, also arranged uneven grooves, ridges or the like between the tightening edges, which in such a case should be positioned in opposition to the direction of the steam passage, so that eddies will be yproduced to the greatest possible extent in the space between the tightening edges. InFig. 2 grooves 20 in the ring bonds have been shown for Ithis purpose. As already pointed out preferably only the-ring bonds of the blade rings yintermediate with respect to `the direction ofthe steam passage are provided with `double tightening@ while one or more of the first and the last ring bondsof the blade rings are provided with one tightening edge only. The double tightening edges therefore are arranged ,at such places in the turbine, .at which the steam pressure in relation to the length of the tightening edge offers the possibility of greater leakage between the blades.

The invention is not to be limited to the .single embodiment shown for the purpose of illustration, since several forms according to this invention `are conceivable. For example, the invention does not depend upon the typeof blades or ring bonds, or whether the turbine is a combined axial and radial flow system. Furthermore, it is immaterial whether the turbine is of the radial flow type having one rotating shaft or turbine disc or two.

Vhat I claim as new and desire to secure by.`Letters Patent of the United States of America. is

1. In Va radial flow elastic uid turbine, a

f plurality of radially spaced relatively rotatable ring bonds for carrying the turbine blades, tightening means comprising a plurality of axially spaced tightening edges extending in generally radial direction from one'bond toward an adjacent bond and means for creating turbulence in the flow of fluid a-xially between said edges.

2. In a radial flow elastic fluid turbine, a plurality of radially spaced relatively rotatable ring bonds for carrying the turbine blades, tightening means comprising a plurality of axially spaced tightening edges extending 'i'n generally radial direction from one bond toward an adj acentbond and means comprising an irregular surface on one of `one bond toward an adjacent bond and means comprising a circumferential groove in said adjacent ring bond and axially between two adjacent tightening edges for .creating turbulence in the flow of fluid axially between said edges.

4. In a radial {flow elastic fluid turbine, :a plurality of radially spaced relatively rotatable pairs of ring bonds for .carrying the turbine blades, each ring bond of one or more of f said pairs being provided with atleast itwo tightening edges/extending in .generally radial direction toward adjacent ring bonds, and circumferential grooves in said adjacent ring bonds, there being a Agroove axially ,between each two of said tightening edges.

3. In a `multiple-stage radial flow elastic fluid turbine, a plurality of radially spaced relatively rotatable ring bonds for `carrying the turbine blades, the ring bonds in the high L pressure stages and low pressure stages yeach having a single tightening edge extending therefrom in generally radial direct-ion toward an adjacent ring bond and the ring bonds in the intermediate pressure stages each having a plurality of tightening edges extending therefrom in ,generally radial direction toward Van adjacent ring bond, and

means for creating turbulence in the .flow of fluid axially kbetween adjacent tightening edges in said intermediate pressure stage.

6. In aA multiple-stage radial flow kelastic fluid turbine, a plurality of radially spaced relatively rotatable ring bonds for carrying the turbine blades, the ring bonds in the high pressure stagesfand the low pressure stages each having a single tightening edge Yextending therefrom in generally radial direction toward an adjacent ring bond, the ring bonds in the intermediate pressure stages each having a plurality of tightening edges extending therefrom in generally radial direction toward an adjacent ring bond and circumferential grooves in the ring bonds of the intermediate pressure stages, said grooves being l disposed ,axially between adjacent tightening edges.

ALF LYSHOLM.

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