US1119731A - Multistage elastic-fluid turbine. - Google Patents

Description

P. SPIESS.

MULTISTAGE ELASTIC FLUID TURBINE.

APPLCi-ATIQN P1LBDAUG.31, 1914.

1,119,731. Patented 116011914,

4maTTED sTATEs PATENT OFFICE.

PAUL SPIESSIOF ZURICH. SWITZERLAND, ASSIGNOB. TO ESCHER, WYSS & CO., A CORPORATION 0F SWITZERLAND.

MULTISTAGE' ELASTIC-FLUID TURBINE.

Speclcatlon-of Letters Patent..

Patented Dec. 1, 1914.

Application tiled August-3l, 1914. Serial No. 859,328.

To all 'whom it may concern:

Be it known that I, PAU!l Spiess, a citizen of the Republic of Switzerland, residing at Zurich, in the Republic of Switzerland, have invented certain new and useful Improvements in Multistage Elastic-Fluid Turbines, of which the following is a full, clear, and exact specification. y

This invention relates to multi-stage axial working elastic (luid impulse turbines which are especially intended to deliver large power at high speeds. Aandavhich are required to have a good etliciency at full as well as partial loads. y

The turbine to which this invention is applicable, consists of bigband low pressure stages in series, the mean rotor dialnet-er in the high pressure stages being less than that in the low pressure stages so that the friction of the wheels, and thetotal pressure on the diaphragmwalls and casing ln the high pressure stages shall not be too, great. In the vlow ressure portions the mean rotor diameter is made as large as possible so that the angles ,ofjthe stationary and moving blades may not be excessive within the permissible limits of lblade length, whereby the energy of the steamshall be lmost efliciently utilized without the use of special exhaust ditinsers.

In axial working elastic fluid turbines of the impulse type at present known` having wheels in the low pressure stages of reater mean diameter than those in the hig pressure stages, the transition from one diameter to another is abrupt. That is, instead of the steam llowin in a generally straight path parallel to tie axis, as it does in passing from one stage to another ofthe same diameter, the steam is diverted in passing from a stage of a certain diameter to a stage of lar er diameter from an axial path to a radin path outwardly, and then again turned parallel to the axis, so as to pass in a straight ine through the wheels of larger diameter. These two right-angled changes in the path of the steam result in considerable losses. Because of changing the direction of the steam from axial to radial and then a ain to axial, the exhaust velocity at the wlieel of lower diameter cannot be used in the following stage, and moreover,there are considerb e energy losses owing to change of direction, eddies and pressure drops. In some constructions where the mean rotor diameter increases from stage to stage, the diameter of the rotor disk relatively to the next following guide channel or nozzle varies abruptly, the mean diameter constant within the following guide channel orfnozzle. This also involves an appreciable energy loss in each stage, duc to loss of exhaust velocity, abrupt changes in the direction of the steam, eddies, etc.

It is the object of this invention to minimize these drawbacks, due to a great diti'erence between the mean rotor diameter of one stage and the mean rotor diameter of the fol lowing'stage, and between the outer diameter. of a rotcr and the following guide channel or nozzle for the next larger rotor, by avoiding abrupt changes in the direction of the steam flow, either between one wheel and the next. larger wheel. or between one wheel and the guide channel o r the nozzle for the next. larger wheel. This is accomplished at least in the low pressure stages or in all of the pressure stages where the mean rotor diameter increases from stage to stage, by evenly increasing not only the mean diameter or the runner wheels but also the diameter of the guide channels between their inlet sides and their exhaust sides. Theseincreases of rotor and guide channel or nozzle diameters from stage to stage are preferably made uniform, but of course this is not absolutely essential so long as abrupt turns in the steam path are avoided. According to thisinventiomtherefore, the path of the steam from the high pressure stages with small diameter wheels to the low pressure stages with large diameter wheels is not exactly parallel tothe axis, with successive abrupt changes. but is divergent in the channels and preferably in approximately a straight line.

The invention is chiefly applicable in the low pressure portion of an axial working elastic tluid impulse turbine, Whether steam or gas. in order to take caro of the rela,- tivoly large volume of exhaust fluid. The high pressure stages may, according to the present practice, have a constant mean diameter, and the remaining low pressure stages have a substantially uniform increasing diameter.- In very large units, hOW- ever, operating at; high speed and espe cally where already the high pressure stages ecause of the necessity of keeping -lnii' f'uiladmissionof lfluid, the invention ulnuid `be:advantageously applied to all stages. A

In the accompanying drawings, Figure 1 a* longitudinal section through an eight stage turbine in which the first four stages haveaconstant mean diameter, and the remaining stages an' increasing diameter ac cording t this invention, and Fig. Q is a longitudinal s ection through a multistage turbine in whichthere 'is an increased diameter from the lrst stage on. In Fig. `1, the mean diameter D steadily increasesbetween stages V and VIII, so that for. instance, the mean diameter D--VIIA is greater than D-VL and also iii each latter stage the exhaust diameter of the guide channel is greater than the inlet diameter E thereof. Thus A-VI is greater than E-VL In this'manner, the steam is carried evenly and without appreciable eddies and pressure losses from one runner wheel to the somewhat larger succeeding runner wheel.

In Fig. 2, is sliownan example wherein the mean wheel diameters successively increase between the first and the last stages, and the inlet and exhaust sides of the guide channel successively increase, as explained above in connection with stage VIof Fig. l. In Fig. Q the first wheel F has lalready full admission through guide channels N. In Fig. l however the last four'stages V, VI, VII, VIII have full admission. It may be stated here, that the runiier wheels may be fitted with one/ yor more rows of buckets. as wheel .F VII in Fig. 2. f j.

By this invention, it will be seen that.

there will be no abrupt changes in the direction of uid flow Iwitli consequent loss of exhaust velocity in passing from the exhaust side of one runner wheel through the suc ceeding guide channels or nozzles to the inlet side of the next runner wheel of larger diameter. Eddies, and pressure drops are likewise avoided, thereby securing increased eleiency.

Having thus' described my invention, I declare that what I claim as new and desire to secure by Letters Patent, is:

1. A multi-stage axial 4workingelastic fluid impulse turbine comprising at least some low pressure stages whose runnerwheel-mean-diameter evenly and .steadily increases from 'stage to stage and whose guide-channel-outer-diameter increases between tlie fluid inlet and exhaust.

9.. A multi-stage axial working impulse (luid turbine comprising a series of stages whose runner-wheel-mean-diameter evenly and steadily increases from stage to stage'v and whose guide=channelouterdiameter increases between the fluid inlet and exhaust. 3. A multistage axial working elastic fiuid impulse turbine comprising at least.

some low pressure stages whose runner- \\lieelnieandiaineter evenly and steadily increases from stage to stage and whose guide-channel-outer-diaineter increases betw-een the fluid inlet and exhaust, certain of the runner wheels having at least two rows of buckets.

In testimony whereof I allix my signature, in presence of two witnesses.

i PAUL SPIESS. 'Witnesses z i HL'LoiiiziCii KELLER,

CARL GUiiLEiz.

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