US1950088A - Turbine - Google Patents

Description

March 6, 1934. F. LJUNGSTROM TURBINE Filed Oct. 15, 1932 2 Sheets$heet l INVENTOR ATTORNEYS.

March 6, 1934. F. LJUNGSTROM TURBINE Filed Oct. 15. 1932 2 Sheets-Sheet 2 dam turbines of this type Patented Mar. 6, 1934 UNITED STATES TURBINE Fredrik Lju'n'gstriim,

corporation of Sweden Application October 15,

Lidingo, Sweden, assignor to Aktiebolaget Spontan,

Stockholm, Sweden, 2.

1932, Serial No. 638,025

In Sweden October 17, 1931 6 Claims.

My present invention relates to radial flow steam or gas turbines of the double rotation type, i. e., with rotors running in opposite directions.

It has previously been a common opinion that are not adapted to effect high power output or for handling admission steam of high pressure.

The principal object of my invention is to provide an economically working radial flow double rotation turbine which may be built for the highest initial pressures used, i. e., for pressures of 50-100 atm., and for very large capacities, for instance 100,000 or more at 3,000 revolutions per minute, without necessitating the division of the turbine into a plurality of sections with a plurality of outlet areas for the exhaust steam as has been necessary hitherto for turbines of such capacities.

A further object of my invention is to provide a turbine of the type referred to, the blades of which are of such shape and its outlet conduits so devised that large steam passages are to be found within the turbine and its tapping or extraction conduits, while requiring only a limited axial extension of the turbine system, thus eliminating injurious vibrations in spite of very high power and high numbers of revolution.

For this reason I provide the turbine with a plurality of chambers in the side plates communicating with different tapping or extraction points within the turbine, from which chambers I conduct the steam quantities withdrawn from difierent temperature levels of the turbine to a plurality of feed-water preheaters for the steam gen erators of the plant, i. e., the steam boiler said preheaters being connected in series. The extraction lines extending from said chambers are divided into a plurality of conduits, particularly for the lowest extraction stage, where large steam volumes are to be handled, and said conduits lead to a common annular collection chamber inside the turbine casing, from which chamber the extraction steam is led by a single conduit to the outside of the turbine casing.

The invention will be more fully described with reference to the accompanying drawings in which connection also other features characterizing my invention will be set forth.

In the drawings:--

Fig. l is a side view of the main parts of a steam turbine plant showing my improved turbine interconnected between two electric turbo-generators;

Figs. 2 and 3 are sectional views taken along the lines 2-2 and 3-3, respectively, of Fig. 1, and

Fig. 4 is an axial section through part of the turbine system from which will be seen not only the blading of the turbine but also the connection of the inlet and outlet conduits for the same.

In the drawings reference character 2 designates the total inner system of the turbine (see Fig. 1). This system consists mainly of two socalled side plates 3 and 4 (see Fig. 4) which are in a known manner connected to the end covers 7 and 8 of the generators 5 and 6 and thus through the generators to the cover or housing 9 surrounding the turbine aggregate. The side plates 3 and 4 are provided with so-called labyrinth plates 10 and 11 cooperating with corresponding plates 12 and 13 connected with turbine discs 14 and 15, respectively, which in turn are rigidly connected to the shafts of the generators. Each one of these turbine discs are in known manner provided with a number of blade rings or blade rows which are so devised and arranged relatively to each other that on passing of the steam through the turbine system said discs are caused to rotate in opposite directions relatively to each other, i. e. a double rotation is obtained.

Each one of the side plates 3 and 4 is provided with two chambers separated from each other, i. e. the side plate 3 with'chambers 16 and 17 and plate 4 with chambers 18 and 19. These chambers, as will be more fully described in the following, communicate with different stages of the turbine system by means of channels through the turbine discs or labyrinth plates, respectively, and a number of conduits are connected to said chambers as will be seen from Figs. 2, 3 and 4, through which steam is admitted to or withdrawn from the turbine. In order to increase the thermal efliciency of a steam plant of the kind referred to, it is desirable to provide a plurality of preheaters (not shown in the drawings) in which the feed water is successively heated from one temperature to another by means of steam withdrawn from the turbine at different stages of expansion therein, so that the first preheating of the feeding water takes place by steam withdrawn from one of the lower pressure stages of the turbine, i. e. relatively to the expansion of the steam one of the last stages, and the further preheating is done by steam withdrawn from expansion stages near to the centre of the turbine, i. e. by steam of increasing temperature.

In order to facilitate the arrangement of a plurality of such tapping or extraction points, my turbine is, as above mentioned, so devised that the admission of steam thereto takes place through one of its side plates only. As apparent from the drawings, plate 3 is provided with a chamber 16 to which the high pressure steam from the steam boilers (not shown in the drawings) is introduced through conduit 26 and its branches 21, 22 and 27. From. chamber 16 the steam is conducted through channels 20 in the turbine disc 14 to the high pressure stage 29 of with respect to its temperature, comes next to the temperature of the steam boilers. The turbine discs 14 and 15 are divided into a number of annular parts so that the different parts of the discs may freely expand under the influence of different temperatures. Such divisions are preferably arranged at the places where the passages 31, 36 and 35 for the extraction of steam are provided.

The remaining steam which has not been withdrawn from the turbine through chamber 18, forming the main'part of the admission steam, fiows through the said first medium pressure stage 30 thereby giving off part of its energy by expansion to the lower temperature and lower pressure prevailing in the annular chamber 33 between the first medium pressure stage 30 and the second medium pressure stage 34. Said chamber 33 communicates, by channels 35 penetrating the turbine disc 14 and the labyrinth plates 12 and 10, with chamber 17 in side plate 3. From chamber 17 conduits 36, 37 and 38 conduct the steam withdrawn from chamber 33 to a common conduit 39 leading to another feed water preheater 'on a temperature level corresponding to the temperature of the steam in chamber 33.

The quantity of steam which has not been withdrawn from chamber 33 in the turbine flows through the second medium pressure stage 34 thereby giving off energy to the rows of blades forming said stage. Further quantities of steam may thereafter be withdrawn from the turbine through channels 36 penetrating the turbine disc 15 and the labyrinth plates 13 and 11 and leading to chamber 19 in side plate 4. To this chamber a number of conduits 40 are connected which, as will be seen from Fig. 3, radially extend therefrom and connect chamber 19 with a collector 41 in the form of an annular chamber or conduit for steam extracted from said chamber 19. From collector 41 a conduit 42 connected thereto leads the collected steam to the feed water preheater of the lowermost temperature level.

By arranging the tapping or extraction conduits as above described so that a plurality of conduits are connected to the tapping chambers of the side plates, the advantage has been obtained, especially as far as concerns the last, i. e. the outmost positioned tapping of the turbine where the specific volume of the steam is very 5? great, that in spite of great steam volumes considerable steam quantities may be withdrawn while maintaining relatively small diameters of the tapping conduits from the turbine system. By this arrangement the axial extension of the turbine system may be kept small so that long shaft ends and long bearing distances may be eliminated which otherwise at high turbine capacities and high numbers of revolution may cause vibrations in the system of such magnitude that the safe running thereof will decrease.

, The collecting chamber 41 for steam withdrawn from chamber 19 through conduit 40 is, as will be seen from Fig. 1, arranged outside the turbine system at a place where sufficient space therefor is available. The arrangement shown in Figs. 1 and 3 of the said collector, which is annularly shaped and axially displaced some distance from the turbine system, is of great advantage as by such arrangement heat conducting connections between the collector and the generator cover or the turbine housing 9, respectively, are eliminated. By said arrangement partial heating of the said generator cover or turbine housing is eliminated which otherwise may cause heat stresses inconvenient for the correct supporting of the turbine.

The remaining steam quantity which has not been withdrawn from chamber 19 further expands in the low pressure stage 45 of the turbine and finally in the last blade row 46 of said stage having arch-curved blades. The blades of the last blade rows of the turbine are constructed in accordance with the principles set forth in my copending application Serial No. 386,241 of August 16, 1929, Patent Number 1,397,172. The last blade row (see Fig. 4) is provided with flexible blades which are curved outwards and obtain their operating shape due to centrifugal force, as has been described in my copending application Serial No. 561,565 of September 8, 1931, by means of which construction up to 30% of the heat drop of the admitted steam may be extracted in the last row of blades. Hereby a high percentage of moisture of the steam in the inner system is prevented whereby Wear of the blades within saidinner system due to water particles contained in the steam is reduced. Instead, said wear will be concentrated at the last blade row where the last great drop of pressure occurs. However, since most of the expansion in this stage takes place at the outside of the blades, the larger part of the moisture has no effect on these blades. Further, since blades of the kind referred to easily may be made replaceable in their blade rings, new blades may without difficulty be inserted if considerable wear should occur.

In order to withstand the wear of the blades due to said moisture or water particles contained in the steam I propose to manufacture the blades from so-called nitrated steel and expose the same to a nitrating process, i. e. a nitration hardening which makes their surfaces very resistant to such wear.

Y In the arrangement shown in the drawings, the tapping or extraction conduits belonging to the inner system of the turbine may, if desired at high load, be used as admission conduits for supplying additional high pressure steam to the turbine.

By the arrangement of the steam admission to the turbine through only one of its side plates I reduce the loss due to leakage along the turbine shaft as the high admission pressure in my turbine is prevailing only on the one packing of the shaft which in Fig. 4 is designated by 50. On the other shaft packing 51 a pressure is prevailing corresponding to that of the first tapping chamber 18. This reduction of the leakage losses serves to increase the economy of the steam plant rel ferred to, i. e. in turbines of high admission pressure, for instance amounting to 50-100 atm., for which pressures my turbine is applicable. The shaft packings 50 and 51 are in known manner constructed as labyrinth. packings and, as indicated by dotted lines in Fig. 4, connected with exhaust conduits for leakage steam or with conduits through which sealing steam in known manner is supplied to the packings.

Though steam is admitted to my turbine through one of its side plates only, suiiicient admission areas are obtained for creating 50,000 100,000 kw output in the turbine due to the specific volume of the admission steam at said high pressures being very small. The provision of sufficiently large admission areas in the turbine disc 14, i. e. sufliciently wide channels 20 therein, is facilitated by my method of fastening the turbine discs on the shaft ends shown in Fig. 4. Due to the arrangement of the tapping chambers in both side plates of the turbine, the channels for tapping steam will penetrate the turbine discs or the labyrinth plates, respectively, at different radial distances from the centre of rotation of the turbine.

What I claim is:-

1. A steam or gas turbine of the double rotation type having in combination with the turbine casing, a collector chamber inside the turbine casing and axially displaced from the central plane of the turbine, and a plurality of tapping or extraction chambers for fluid from difierent pressure and temperature stages of the turbine, the tapping chamber corresponding to the lowermost pressure stage being provided with a plurality of tapping conduits connecting said chamber with said collector chamber.

2. A steam or gas turbine of the double rotation type having in combination with the turbine casing, an annular collector chamber inside the turbine casing, and a plurality of annular tapping or extraction chambers for fluid from different pressure and temperature stages of the turbine, the tapping chamber corresponding to the lowermost pressure stage being provided with a plurality of tapping conduits extending radially therefrom to said collector chamber.

3. A steam or gas turbine of the double rotation type comprising in combination with the rotatable blade-carrying members a plurality of tapping or extraction chambers at the sides of said blade-carrying members respectively in communication with different pressure and temperature stages of the turbine, an annular collection chamber for a fluid of relatively low temperature and pressure, and a plurality of radially disposed conduits distributed around the axis of the turbine and in communication with said collection chamber and the tapping chamber which corresponds to the lowermost pressure stage.

4-. A steam or gas turbine of the double rotation type comprising in combination with the rotatable blade-carrying members a plurality of tapping or extraction chambers at the sides of said blade-carrying members respectively in communication with different pressure and temperature stages of the turbine, an annular collection chamber for a fluid of relatively low temperature and pressure, and a plurality of radially disposed conduits distributed around the axis of the turbine and in communication with said collection chamber and the tapping chamber which corresponds to the lowermost pressure stage, said collection chamber being displaced both axially and radially with respect to said blade-carrying members.

5. A steam or gas turbine of the double rotation type comprising, in combination with rotatable blade-carrying members, an annular tapping or extraction chamber adjacent to one of said members and in communication with a relatively low pressure stage of said turbine, an annular collection chamber of larger diameter than said tapping or extraction chamber for collecting fluid from said tapping or extraction chamber, and a plurality of conduits connecting said tapping or extraction and said collection chambers.

6. A steam or gas turbine of the double rotation type comprising, in combination with rotatable blade-carrying members and a casing enclosing the same, an annular tapping or extraction chamber adjacent to one of said members and in communication with a relatively low pressure stage of said turbine, an annular collection chamber for collecting fluid received from said tapping or extraction chamber, and a plurality of conduits connecting said tapping or extraction and said collection chambers, said collection chamber being displaced axially and radially from the blade-carrying members but disposed within the turbine casing in surrounding relation with the end of the machine driven thereby.

FREDRIK LJUNGSTRDM.

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