US1375075A - gaumann - Google Patents

Description

BAUIVIANN.

STEAM TURBINE,

APPLICATION FILED AUG.24.1917.

Patented Apr. 19, 1921.

2 SHEETS-SHEET l \NVENTOR K. BAUMANN.

STEAM TURBINE.

APPLICATION FILED AUG.24, I917.

Patented Apr. 19, 1921.

2 SHEETS-SHEET 2 I INVE NTO R MJJW'MM UNITED STATES FATE '1 rina.

KARL BAUMANN, OF URMSTON, ENGLAND, AEBSIG-BTOR T9 THE BR SH WESTING- HOUSE ELECTRIC AND IvIANUFAGTUBING CGIQIEPANY, LIMITED, A COMPANY ORGANIZED UNDER THE LAWS OF GREAT BRITAIN.

STEAM-TURBINE.

Application filed August 24, 1917.

To all whom it may concern:

Be it known that I, KARL BAUMANN, a citizen of the Confederation of Switzerland, and a resident of Urmston, in the county of Lancaster, England, have invented a new and useful Improvement in or Relating to Steam-Turbines, of which the following is a specification.

This invention relates to steam turbines of the axial flow type.

As in a, steam turbine of this type the peripheral velocity of those parts of the moving blades which are nearer the shaft is less than that of the parts near the outer ends of the blades, the velocity of the steam leaving the inner portions of the blades 2'. 6. those portions nearer the turbine shaft is greater than that of the steam leaving the outer portions of the blades. It is, however, desirable that the whole of the steam leaving the moving blades should be at approximately the same velocity when it enters the exhaust casing.

This is accomplished, according to the present invention, by providing guide blades, nozzles, velocity converting passages or the like for partly reconverting into pressure energy the velocity energy of the whole or part of the steam passing from the moving blades to the exhaust, so designed that the steam from every part of the blading enters the exhaust at substantially the same velocity.

Where the turbine has only a single row of moving blades from which the steam passes to the exhaust such guide blades, nozzles or the like are so designed as to provide passages which diverge to a greater extent in a radial direction as they approach the turbine sha t.

In the case of a turbine in which the steam passes from a plurality of rows of moving blades to the exhaust it will be found that the leaving velocity of the steam passing from a row of moving blades near the high pressure end of the turbine is usually greater than that of the steam passing from a row of moving blades nearer the exhaust end of the turbine. Guide blades, nozzles or velocity converting passages are therefore provided through which the steam leaving some or all of the vrows of moving blades is caused to pass on its way to the Specification of Letters Patent.

Patented Apr. 19, 1921.

Serial No. 187,962.

exhaust and in which the remaining velocity energy ofthe steam is partly reconverted into pressure energy to such an extent that the steam leaving all the rows of blades will be at approximately the same velocity when it enters the exhaust casing.

It will sometimes be found suflicient to provide such velocity converting passages for the steam leaving only the row or rows of moving blades nearest the high pressure end of the turbine. Diverging passages may also advantageously be provided for the steam leaving the final row of moving blades similar to those hereinabove described for a turbine in which the steam passes from a single row only of moving blades to the exhaust.

In the accompanying drawings Figure 1 is a longitudinal section of a turbine of the axial flow steam type with one form of guide lades forming diverging passages for partly reconverting into pressure energy the velocity energy of the steam before it enters the exhaust casing constructed in accordance with the present invention, Figs. 2 and 3 be ing sections taken respectively on the lines II-II and II-IIII of Fig. 1. Fig 4 illustrates a turbine provided with means constructed in accordance with the present invention for partly reconverting the velocity energy of the steam leaving an inner portion only of the final row of moving blades, Fig. 5 being a section taken on the line V--V of Fig. 4.

In Fig. 1 the steam passes to the exhaust casing 6 from the outer portions of the rows of moving blades 7, 8 and 9 and from the whole of the final row of moving blades 10. A row of fixed guide blades 11 is located opposite the outer portion of the row of moving blades 7 which, as shown in Fig. 2, form between them diverging passages through which the steam leaving the outer portion of said row of moving blades 7 passes on its way to the exhaust casing 6. Said row of fixed blades 11 are inclosed at their outer ends by a shrouding or wall 12 which may conveniently be formed in conjunction with the shrouding or wall 13 for the fixed guide blades preceding the outer ends of the moving blades 8. The passages between the blades 11 also diverge in a radial direction. Similar fixed. guide blades 14;

mounted on the shrouding 15 for the fixed guide blades preceding the outer ends of the moving blades 9 and inclosed by a shrouding 16 are also provided in connection with the outer portion of the row of moving blades 8 to form, as shown in Fig. 3, diverging passages through which the steam leaving said outer portion of the blades 8 passes before reaching the-exhaust casing 6.

Similar fixed guide blades may a-so be provided for the steam leaving the outer portion of the row of moving blades but as the leaving velocity of the steam passing from the rows of moving blades 7 and 8 is usually greater than that of the steam passing from the moving blades 9 and 10, the provision of diverging passages for the steam leaving the rows of moving blades 7 and 8 will usually be found suiiicient to insure that the steam leaving all the rows of moving blades 7, 8, 9 and 10 will be at approximately the same velocity when it enters the exhaust casing 6.

In Figs. 4: and 5 a row of fixed guide blades 17 is provided supported on adrum 18 attached to the exhaust casing 6 and in closed by a circumferential wall or shrouding 19. In this construction the fixed blades 17 are of such a height that only the steam leaving the inner portion of the final row of moving blades 20 passes through the diverging passages formed between the fixed blades 17 and the drum 18 and shrouding 19. As the peripheral velocity of the inner portion of the inner row of moving blades 20 is less than that of the outer portion oi": said row of blades the velocitv of the steam leaving the inner portion of said blades is higher than that leaving the outer portion thereof. The higher velocity energy of the steam l aving the inner portion of the moving blades 20 will be partly reconverted into pressure energy by the diverging passages formed as aforesaid, with the result that the steam leaving the outer portion of the row of blades 20 and that leaving the fixed blades 17 will be at approximately the same velocity on entering the exhaust casing 6. The absolute pressure immediately behind the moving blades 20 will be lower in the inner portion than in the outer portion, and in order to prevent leakage and other losses it is advisable to separate the inner tier from the outer tier of the moving blades by dividing lugs 21, and to provide dummy strips 22 to obtain a small clearance between the lugs and the wall 19.

Diverging passages constructed as describedwith reference to Figs. 4 and 5 may advantageously be employed not only in turbines having one row only of moving blades from which the steam passes to the exhaust but also in connection with the final row of moving blades of turbines in which the steam passes to the exhaust from a plurality of rows of moving blades as illustrated for example in Fig. 1 of the accompanving drawings.

By adding the above described row or rows of guide blades, nozzles, or diverging passages the leaving energy in the exhaust steam will be partly reconverted into pressure immediately after leaving a row or rows of moving exhaust blades and before the steam enters the exhaust casing or passages, thus-increasing the erficiency of the turbine.

The invention is not limited to the constructional forms herein described and illustrated which have been given by way of example only as the diverging passages may be formed in various other ways lying within the scope of the invention as hereinafter definel by the appended claims.

I am aware that it is not broadly new to provide means for partially reconverting into pressure energy the velocity energy of the steam passing from the blading of a turbine to the exhaust and I make no such claim.

I claim as my invention:

1. Inan axial flow steam turbine, a steam receiving chamber adapted to receive the steam passing through the turbine stages upon a plurality of annular, deflecting surfaces, the angle of deflection of each surface varying proportionally with the velocity of the steamreceived thereupon.

2. In an axial flow steam turbine, a plurality of vanes and passages formed in the turbine casing for the steam leaving difi'ercnt annular portions of said vanes, adapted to convert the respective velocity energy of the'steam from each of said portions into. a standard velocity energy.

3. In an axial fiow steam turbine having an exhaust chamber and a moving row of blades adapted to discharge thereinto means for converting the velocity energy of the steam leaving a portion of said blades into a velocity energy equal to that of the steam leaving another portion of said blades.

4. In an axial flow steam turbine having an exhaust chamber and a final row of moving blades conversion devices arranged to receive the steam issuing from the inner porlions of said blades and adapted to convert some of its velocity energy into pressure energy so that the velocity of the steam issuing from said devices will be substantially the same as the velocity of the steam leaving the outer ends of said blades.

In. an axial flow steam turbine; an ex haust' chamber and a final row of blades and conversion devices carried within said exhaust chamber and positioned to receive the steam issuing from those portions of said blades nearest the turbine shaft; said conversion devices being proportioned so as to convert sufficient of the velocityienergy of the steam passing therethrough into pressure energy so that the velocity energy of the steam issuing therefrom will be substantiallv equal to the velocity energy of the steam leaving the outer ends of said blades.

6. In an axial flow steam turbine, vanes, a steam receiving chamber adjacent said vanes and annular guides in said chamber arranged concentrically with the axis of the turbine and with their surfaces inclined 1 with respect to said axis, the angle of in clination of the respective guides decreasing from said axis to the circumference of said chamber.

In testimony whereof I have hereunto subscribed my name this tenth day of July, 5

KARL BAUMANN. Witnesses WILFRED MORRIS, F REDERIOK NIXON.

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