US1944537A - Radial flow elastic fluid turbine - Google Patents

Description

Jan. 23, 1934. o. A. WIBERG ET AL 1,944,537

RADIAL FLOW ELASTIC FLUID TURBINE Filed June 2, 19:52

F1g.5. I

$19 zzadzuaf 2 45 m I J? Y L/ k7 ifi u ay Jwwzw Patented Jan. 23, 1934 j UNITED STATES PATENT OFFICE Swed Application June 2, 1932, Serial No. 614,989, and in Germany June 4, 1931 Claims.

This invention relates to radial flow elastic fluid turbines having either two members running in opposite directions and each supporting concentric series of blades, or one rotating mem- 6 ber supporting series of blades alternating with series of guide blades supported by a fixed member; Reference is made to our copending application Serial No. 614,190, filed May 28, 1932, and the application of Moller Serial No. 614,189, filed May 28, 1932.

In the standard forms of such turbines considerable losses arise on account of leakage, eddying and throttling when the elastic fluid flows through the concentric series of blades whereby the efficiency of the turbine is reduced. Such losses increase as the pressure of the elastic fluid and the diameter of the blade rings are increased. In order to reduce the said losses it has been proposed to use the radial flow turbine as a low pressure turbine combined with a high pressure axial flow turbine which latter has a greater efficiency than the radial flow turbine at high pressures and great speeds. Such combinations are, however, in many cases not desirable and actually, the development goes nowadays towards the manufacture of more and -more large units working with steam of ever greater pressures and higher temperatures, which causes special difiiculties in building radial flow turbines working with high efficiency. 9 It has already been proposed to build radial flow turbines in large units by constructing the turbine with two or more groups of blades axially displaced in relation to each other and operated in series by the steam. When the steam has passed through one group of blades from the centre outwards to the outer-most blade ring of said group it is again led inwards to the next group of blades, and so on. Said latter group may, of course, have the same or approximately the same diameter as the first one. The turbines of said type hitherto proposed have, however, the, drawback of still greater losses. due to leakage than the standard radial flow turbine on account of the increased numbers of leaks.

The chief object of this invention is to so con struct a radial flow turbine having two or more axially displaced sets of bladings to be operated in series by the steam that the losses due to leakage are reduced to a minimum.

A further object of the invention is to facilitate the supply of overloading steam and the discharge of bleeding steam.

A further object is to secure an effective balancing of the rotary members in a simple manner.

The invention consists, chiefly, in an improved journalling of the turbine disc or discs, as will be more fully described with reference to the accompanying drawing in which, Fig. 1 is an axial section of a part of a radial flow steam turbine according to the invention, Fig. 2 is an axial section of a complete steam turbine according to the invention, and Fig. 3 is an axial section of a steam turbine according to the invention having only one rotating member.

Referring now to Fig. 1 of the drawing, the steam turbine shown is of the type having blade wheels running in opposite directions, each rotating member comprising two sets of blades axially displaced in relation to each other and adapted to be operated by the steam in series. 1 and 2 are two shaft ends, each supporting a turbine disc 3 and 4, respectively, said discs being adapted to rotate in opposite directions. The shaft end 2 supports further a second turbine disc 5 which, preferably, is mounted on said shaft in such manner that it looks the disc 4 to the shaft end 2. The disc 3 supports at its periphery a disc 6 extending inwards. Between the discs 3, 5 and 4, 6 bladings 21 and 22 respectively of normal type are provided. Similar bladings may also, if desired, be provided between the discs 5 and 6. The shaft ends 1 and 2 are in usual manner surrounded by concentric steam chambers 7 and 9 respectively which in turn are surrounded by outer concentric chambers 8 and 10-respectively. Between the shaft ends 1, 2 and the chambers 7, 9 packings 11 and 12 respectively are provided. Labyrinth packings 13 and 14 to gether with their associate discs 15, 16 and 17, 18 respectively are provided between the steam chambers and the turbine discs. The chamber 7 is provided with a steam supply pipe-19 and openings 20 in the turbine disc connect the chamber 7 with the centre of the blading 21. Between the chambers 7 and 8 a valve is provided. Borings 23 in the discs 15, 16 and the turbine disc 3 are provided for connecting the chamber 8 with an intermediate stage of the blading 21.

The connecting channel 24 between the blading 21 and the blading 22 is at its smallest diameter connected with the chamber 9 by means of openings 25 in the turbine disc 4. Between the chamber 9 and the chamber 10 a valve 26 is provided and from the chamber 10 borings 27 lead through the discs 18, 1'7 and the turbine disc 4 to an intermediate stage of the blading 22. A pipe 28 is connected to the chamber 9. To the chambers 8 and 10 pipes 29 and 30 respectively may be connected, said pipes being normally shut oif by valves (not shown).

The high pressure steam is supplied to the chamber 7 through the pipe 19, flows through the openings 20 to the blading 21 and flows radially outwards through said-blading. When the valve '70 is opened high pressure steam is supplied to .the chamber 8 and from'the latter through the borings 23 to an intermediate stage of the blading 21, if an overload is required. When the valve 70 is closed steam may be discharged from said intermediate stage of the blading and conducted to any desired place through the pipe 29.v

After the steam has passed the connecting channel 24 inwards the whole steam quantity,

or, if desired, a part thereof only flows outwards through the blading 22. If only a part of the steam is supplied to the blading 22, the remainder is discharged through the openings the chamber 9 and the pipe 28. On the other hand, the chamber 9 may be used to supply overloading steam to the blading 22 through the pipe 28.

A further possibility of overloading the turbine is afforded by the valve 26, in as much as a part of the steam supplied to the chamber 9 may be supplied to the chamber 10 and from the latter to an intermediate stage of the blading 22 through the boring 2'7.

Aturbine as above described is of a simple and reliable construction and when arranged as a bleeder the bleeding pressure may be varied within wide limits. The lowpressure part of the turbine represented by the blading '22 should, however, in such case never be completely inactive. The turbine may be used as back-pressure turbine or as condensing turbine, at will.

In order to secure a good balancing of the rotating parts the labyrinth packing of the low pressure part represented by the blading 22 should be provided with larger plates than the packing belonging to the high pressure part. The dimensions of the labyrinth packing belonging to the low pressure part may be reduced, if means for a pressure equalizing between the packings 13 and 1-4 is provided. According to Fig. 1 such pressure equalizing is effected by means of openings 50 in the disc 15, a collecting chamber 51, a pipe 52, a collecting chamber 53 and openings 54 in the disc 18. I

By the use of free bearing shaft ends in a similar manner as in a standard radial flow turbine with blade wheels running in opposite directions it is possible, in spite of the blading being divided in two or more groups axially d-isplaced in relation to each other, to avoid any increase of the losses due to leakage, in as much as only two leaks on each side of the turbine are present.

In Fig. 2 the arrangement of the turbine in its housing is shown. The construction of the turbine shown in Fig. 2 differs from that shown in Fig. 1 only in this that moving blades 31 are provided between the discs 5 and 6. Also in this embodiment a one-sided steam supply is shown though, of course, it would be possible also to have a double-sided steam supply. The outer packing discs 15 and 18 form in a similar manner as in the embodiment above described the inner walls of steam-chambers which latter are connected'to the turbine housing 34 by means of expansion rings 32, 33.

In order to improve the balancing and to reduce the blade leakage as regards the first blade ring on the high pressure side of the turbine,

- said blade ring is formed as a box 35 secured to the turbine disc 3 and closed towards the turbine ing balancing when-steam is supplied from an intermediate stage through borings in the turbine disc and the labyrinth disc to the labyrinth packing, means are provided in Fig. 2 for the purpose of supplying steam of different pressure as balancing steam to the labyrinth packing 14, said means consisting of borings 36 in the turbine disc 5 and in the shaft end 2.

Fig. 3 shows a modification of the turbine having one rotating member only and adapted to be .used as an auxiliary turbine or as an independent turbine. The housing 39 of a toothed gear, an electric generator or a turbine with a shaft 40 journalled in a bearing 41 supports the turbine housing 42. To the shaft 40 are secured two turbine discs 43, 44, of which the disc 43 has blade rings on both sides. The guide blades are supported by the turbine housing 42. Steam may be supplied through the pipe 45 and discharged through the pipe 46. In order to secure an effective tightening against the atmosphere and a balancing of the axial thrust, thrust discs with or without an intermediate labyrinth packing 47 are provided. In the latter case a shaft packing 48 similar to that shown in Fig. 1 is required. Fig. 3 shows in the upper half the packing 48 and in thelower half the labyrinth packing 4'7, but it should be understood that said means are alternative modes of effecting the tightening shown in the same embodiment of the turbine.

Turbines of the kind described having freebearing shaft ends and one-sided steam supply, which latter is to be preferred though also a double-sided supply may be used, have the advantage of a reduced leakage in the labyrinth packings and the shaft packings and also the advantage of a reduced blade leakage. The lastmentioned effect is attained on account of the reduced diameter of a greater number of blade rings in comparison with a standard radial flow turbine. In other words, in the high pressure part of a turbine of the kind described the sums of the squares of the peripheral speeds of the said blade rings, the sum 10 is less than in a standard radial flow turbine. The efficiency, is, therefore, greater than in the standard radial flow turbine under the same conditions of operation. The turbine constant C which is equal to wherein G is the steam quantity, 1) the specific volume of the steam and p the steam pressure, may be reduced in the turbines described to such a value that it amounts only to of the constant of the standard radial flow turbine and the efficiency will be better than hitherto also with the smallest value of the turbine constant.

The axial thrusts remain constant also at over-,

loading. As regards the bleeder, either it is constructed as back pressure turbine or as condensing turbine, it is possible to choose the value of the sum 11. which is most suitable for the bleeding pressure and notwithstanding to secure small losses due to leakage in the packings before the low pressure part.

It is evident that the constructional features of the invention may be modified without departing from the scope of the invention. For in-,

stance, more than two groups of blades may be used in which case the discs of one direction of rotation are connected to each other at their periphery, while the discs of the other direction shaft.

What we claim is:

1. In a radial flow elastic fluid turbine having blade discs rotating in opposite directions, steam chambers on both sides of the turbine, labyrinth packings in connection with said steam chambers, and a connection between intermediate points of said labyrinth packings adapted to secure a pressure equalizing between said packings.

2. In a radial flow elastic flow turbine having blade discs rotating in opposite directions, means forming a steam chamber on the high pressure side of the turbine, a labyrinth packing in connection with this steam chamber, a labyrinth packing for balancing purposes on the low pressure side of the turbine, and a connection between inner stages of the turbine blading and the inner periphery of the labyrinth packing on the low pressure side of the turbine.

3. In a radial flow elastic fluid turbine having blade discs rotating in opposite directions, means forming a steam chamber on the high pressure side of the turbine, a labyrinth packing in connection with this steam chamber, a labyrinth packing for balancing purposes on the low pressure side of the turbine, and one turbine disc having passages formed therein and in its shaft, said passages connecting inner stages of the turbine blading and the inner periphery of the labyrinth packing on the low pressure side of the turbine.

4. A radial flow elastic fluid turbine, comprising two free-bearing shaft ends adapted for rotation in opposite directions, a plurality of axially spaced discs of substantially the same outer and inner diameters forming annular spaces therebetween and forming channels between said spaces alternately at the inner and outer periphery thereof, every second disc, including one end disc, being connected to one shaft end at its inner periphery, the other end disc being connected to the other shaft end at its inner periphery, and the remaining discs being carried by said other end discs at their outer peripheries, and concentric bladings carried by a surface of each disc.

5. In a radial flow elastic fluid turbine, axially spaced discs of substantially the same outer and inner diameters forming a plurality of axially spaced annular spaces between themselves and forming channels between said spaces alternately at the inner and outer peripheries thereof, a free-bearing shaft end carrying every second disc, another free-bearing shaft end to carry the other discs, concentric bladings in every second space, means forming a chamber on the outer side of each end disc in communication with the inner periphery of the respective end space for supplying fluid to the turbine, means forming another chamber, borings through an end disc communicating with said other chamber and said end space providing for fluid transfer between said chamber and said end space, said borings being located between the inner and outer peripheries of said end disc.

OSCAR ANTON WIBERG.

OLOV MLLER.

Images