US1343956A - Steam-turbine - Google Patents

Description

K. BAUMANN.

STEAM TURBINE.

APPLICATION FILED AUG-23, 1917.

1 ,343,956. Patented June 22, 1920.

INVENTOR axg ol K. BAUMANN.

STEAM TURBINE.

APPLICATION FILED AUG-23. 191?.

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INVENTOR $14M K. BAUMANN.

STEAM TURBINE.

APPLICATION FILED AUG-23, 1917.

Patented June 22, 1920.

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IN V EN TOR. 42

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umrsn STATES PATENT OFFICE.

KARL BAUMANN, OF URMSTON,- ENGLAND, ASSIGNOR TO THE BRITISH WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY LIMITED, A COMPANY ORGANIZED UNDER THE LAWS OF GREAT BRITAIN.

STEAM-TURBINE.

Specification of Letters Patent.

Patented J une 22, 1920.

- Application filed August 23, 1917. Serial No. 187,858.

' flow typein which the/steam flowing in substantially the same direction throughout a low pressure part of the turbine is segregated into annular portions which are expanded at different rates and pass from'a plurality of rows of movingblades totho exhaust. v

The present invention is a modification of that set forth in the above referred to patent spectively on the lines and according thereto the segregated annular portions of steam flowing through the turbine are either expanded at approx1- mately the same rate ofthe inner portion or portions of steam are expanded-at a slightly greater rate than the outer port1on or portions.

In order that the-invention may be clearly understood two forms in which it may be carried into eflect are shown by way of example in the accompanying drawings in which Figure 1 is a longitudinal vertical section of the upper half of a turbine embodying the invention and corresponds to Fig. 1 of the drawings accompanying the aforesaid patent.

Figs. 2'and 3 show sections of portions of the blading on an enlar ed scale taken re- --X and ZZ of Fig. 1. Figs. 4 and 5 are sections of the blading of a modified form of turbine, taken respectively on lines corresponding-to the lines X-X and ZZ of Fig. 1, showing an alternative design of blading which may be employed. a

Fig. 6 is a fragmental sectional view of a portion of the turbine illustrated in Fig. 1. Figs. 7 and 8 are expansion and yelocity diagrams respectively of the steam passing through the inner and outer tiers of blading shown in Fig. 6 and indicate the expansionand velocity of steam when the blade conditions are such that the steam is expanded at tion .23.

blades 14 in the diaphra a greater rate in the outer than in the inner tier, as described in the referred to application, and when the expansion through both the inner and outer tiers of stationary blades takes place at approximately the same rate.

Figs. 9 and 10 are respectively expansion and velocity diagrams of the steam when, in accordance with this invention, the expansion of the steam takes place at a greater rate in an inner than in an outer tier of blades.

Referring now to Fig. 1, the turbine cylinder is indicated at 1 and the exhaust casing at 2. The turbine shaft is indicated at 3 and the steam inlet at 4. The inlet nozzles are shown at 5 and the. first wheel at 6 provided with. moving blades 7 as usual. Said nozzles and moving-blades comprising the first stage are succeeded by further rows of stationary nozzles 8, 8 andmoving blades 9, 9, forming subsequent stages in-the usual way. The row of stationary blades 10 and cooperating moving blades 11 are each provided with a circumferential wall 12, 13'

respectively, which divide the blades 10, 11

into inner and outer portions. lhis dividing wall may be formed by providing the blades with lugs or flanges at an intermediate point in their length.-

The inner portion of blades 10 and 11, forming the'inner tier, namely, that tier nearest the turbine axis, is designed so as to expand the steam flowing through it at. a greater-rate than that at which the steam flowing through the outer tier of these blades, namely, that tier lying farthest from the axis, is expanded. The blades may also be designed so that the expansion will be equal in both tiers. The stationary and moving blades 10, 11 are followed by a further row of stationary blades 14 and cooperating moving blades 15, the former being here shown as consisting of two portions, a' main portion 22 and an outlet por- As illustrated, the stationary blades 14 are supported in position in a diaphragm 16 which is held in position by means of lugs 17, 18 engaging with a web 19 extending between the turbine cylinder 1 and a guide wall 20 in the exhaust casing 2. The outer 'ends of the stationary guide 16 are provided with an inclosing walIl ir rim 21 which separates the steam passing through the stationary blades 14 from that leaving the outer portions of the moving blades 11.

The operation of the turbine, constructed as above described, is as follows The steam admitted through the inlet nozzles 5 flows through the moving blades 7 and then passes through the several stages 8, 9, 8 9 and so on in succession in the usual way until it reaches the fixed guideblades 10 and moving blades 11 where the steam is divided into two portions by the c rcumferential walls 12, 13.

Referring to Figs. 6 to 8, the expansion of the steam passing through the outer tier of the blades 10, 11', and through the inner tier of these blades and the blades 14 and 15 of Fig. 1 in those cases in which the steam is expanded at a greater rate in the outer than in the inner tier, as described in the aforesaid specification, is respectively indicated in Fig. 7 by the dotted lines a and b, from which it will be seen from the dotted line a that the steam is expanded down to its final pressure in the outer tier of the stationary blades 10 and continues at the same pressure through the outer tier of moving blades 11, the blading shown in Fig. 1 being that of an impulse turbine. The expansion in the inner tier of the stationary blades 10 is, as shown by'the dotted line b, not continued so far but is completed in the secondary blades 14.

When according to the present invention the expansion through boththe inner and outer tier of the stationaryblades 10 takes place at approximately the same rate, this is indicated by the full line 0 which coincides with the dotted line a, the steam remaining at the same pressure as it passes through the inner and outer tier of the moving blades 11 and through the stationary blades 14 and moving blades 15. WVith the steam expanded at a greater rate in the outer than in the inner tier of blades, as described in the referred to application and shown by the dotted lines a and b in Fig. 7, the corresponding velocity of the steam passing through the outer tier of the blades 10 and 11 is shown in Fig. 8 by the dotted line 6 from which it will be seen that a considerable part of the velocity is absorbed in the outer tier of the moving blades 11. The velocity-of the steam as it passes through the inner tier of the stationary blades 10 and moving blades 11 and through the stationary blades 14 and moving blades 15 follows the dotted line 01, indicating that the velocity of the steam leaving the inner tier of moving blades 11 is again increased in the stationary blades 14 and absorbed in the final row of moving blades 15.

In the present invention the velocity of the steam as it passes through the inner the steam takes place after leaving the stationary blades 10 the velocity being fractionally abstracted in the two rows of moving blades 11 and 15. The velocity of the steam in the outer tier of stationary blades 10 and noving blades ll'follows the full line e which coincides with the dotted line 6, which indicates the velocity in this tier of the blades withthe steam expansions as described in the above mentioned specification.

Figs. 9 and 10 are respectively expansion and velocity diagrams for the. case in which, in accordance with this invention, the expansion of the steam takes place at a greater rate in an inner than in an outer tier of blades. For the sake of comparison the expansions and velocities of the steam in which, as describe l'in the referred to application, Serial No. 105,409, the expansion takes place at a greater rate in an outer than in an inner tier of the blading are also shown in these figures by the dotted lines a, b,-d and e which are similar to those in Figs. 7 and 8.

The steamin passing through the inner tier of stationary blades 10 and moving blades 11 and through the stationary blades 14 and moving blades 15 expands, as indicated, by the full line k. In the outer tier of the stationary blades 10 and moving blades 11 the expansion of the steam takes place in accordance with the upper full line Z which coincides with the expansion in the outer tier of these blades as described in the aforesaid specification and indicated by the dotted line a.

Referring to Fig. 10, the velocity of the steam passing through the inner tier of the stationary blades 10 and moving blades 11 and through the stationary blades 14 andmoving blades 15 is indicated by the upper full line on from which it will be seen that the velocity resulting from the expansion of the steam in the inner tier of the stationary blades 10 is fractionally abstracted in the moving blades 11 and 15. Part of the velocity resulting from the expansion of the steam passing through the outer tier of the stationary blades 10 is abstracted only in the outer tier of the moving blades 11, as shown by the full line a.

It will be observed that as the expansion of the steam in the inner tier of stationary blades 10 is slightly greater than in the outer tier of these blades the stationary blades 14 are in this form of the invention designed to compress the steam passing through them as indicated by the rise in the line 70 in Fig. 9 in order that the steam may arrive at the exhaust at approximately the same pressure as the steam leaving the outer tier of moving blades 11. It will also be observed that the velocity of the steam correspondingly falls as it passes through the fixed blades 14, as shown by the downward inclination of the line m in Fig. 5, some of its velocity energy being .transformed into pressure energy as it passes through these blades.

The exit angles of both the inner and outer tiers of the moving blades 11 may either be the same or the exit angles of the inner tier may be greater than those of the outer tier. In either case the velocity of the steam leaving the inner tier of the moving blades is greater than that of the steam leaving the outer tier because the peripheral velocity of the inner tier is less than that of the outer tier of moving blades, and this difference in velocity is accentuated where. the exit angles of the inner tier of moving blades are greater than those of an outer tier.

With the blading constructed as shown in Figs. 2 and 3 in which the exit angles both of the inner and outer tier of the blades 11 are the same, the circumferential dividing walls 12, 13 shown in the drawings accompanying the specification of the aforesaid patent may be omitted either in the guide blades 10 or in the moving blades 11, or in both.

With the alternative design of blading shown in Figs. 4 and 5 the exit angles w'|-y of the inner tier of the moving blades 11, Fig. 5, are as shown greater than the exit angles 40 of the blades in the outer tier of the moving blades 11, Fig. 4. The velocity of the steam leaving the inner tier of the moving blades 11 will be greater than the velocity of the steam leaving the outer tier of these moving blades because the peripheral velocity of said inner tier is less than that of said outer tier and also because the blade angles are greater in the inner than in the outer tier of the moving blades 11. -The greater part of the remaining energy of the steam leaving the inner tier of the moving blades 11 will in this design of the blading also be abstracted in With blading of the kind shown in Figs.

4 and 5 the circumferential dividing walls 12, 13 are preferably retained although the dividing wall 13 in the moving blades may in some cases be dispensed with.

Although the invention has been hereinabove described in connection with a turbine constructed as shown in Fig. 1 of the drawings of the said Patent No. 1,302,282 it is to be understood-that any form of turbine constructed in accordance with theinvention set forth in the said patent and shown for example in Figs. 2, 3 and 4 of the drawings thereof may have its blading in accordance with the present invention.

It is also to be understood that the remaining energy of the steamdeaving an inner tier of moving blades may be fractionally abstracted in two or more succeeding rows of moving blades instead of being abstracted in a single row of moving blades only, as shown in the accompanying drawings.

It should be further understood that the various expansions of the steam and the velocities corresponding thereto indicated in the diagrams of Figs. 7 to 10 are given by way of example only in order that a clear understanding of the invention may be obtained and that the steam expansions and velocities may be varied considerably from those indicated in said diagrams without subscribed my name this tenth day of July,

KARL BAUMANN. Witnesses:

WILFRED MORRIS, FREDERICK NIXON.

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