US932849A - Enforced-flow elastic-fluid turbine. - Google Patents

Description

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ENFOROED FLOW ELASTIC FLUID TURBINE.

APPLICATION FILED JAN.21, 1907.

932,849, Patented Aug. 31, 1909.

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ENFORUED PLOW ELASTIC FLUID TURBINE.

APPLICATION FILED JAN. 21, 1907.

Patented Aug. 31, 1909.

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ENFORCED FLOW ELASTIC FLUID TURBINE.

APPLICATION FILED JAN. 21.1

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UNITED STATES PATENT OFFICE.

WILLIAI L. B... EIIET, OF SOHENEGTADY, NEW YORK, ASSIGNOB T0 GENERAL ELECTRIC GOIPANY, A CORPORATION OF NEW YORK.

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Specification 0! Letters Patent.

- Application filed January 21, 1907. Serial No. 353,195.

To all whom it may concern:

Be it known that I, WILLIAM L. R. EM- MET, a citizen of the United States, residing at Schenectady, countyof Schenectady, State of New York, have invented certain new and useful Improvements in Enforced- F low Elastic-Fluid Turbines, of which the following is a specification.

The present invention has for one of its objects to improve the-economy of the wellknown Curtis type of elastic-fluid turbine.

A further ob ectis to provide-a turbine of an improved construction for attaining the first-mentioned object.

In carrying out the invention the turbine is provided with as many stages as are necessary to effectively extract the energy from the steam or other elastic fluid. The stages may perform equal or unequal amounts of work as best suits the requirements. Between the initial source of supply and the first stage a certain predetermined drop in pressure exists, and between said stage and each of the succeeding stages the pressure drops step by step; In practice I find it desirable to have a greater pressure drop in the first stage than in each of the succeeding stages, so asto reduce the rotation losses,

and also to avoid imposing undue strains on the wheel casing and the diaphragm or partition between the first and second stages. In the high-pressure'stages only a portion of the wheel buckets are active while in one or more of the low-pressure stages all of the wheel buckets are active. The passages in the expanding nozzle discharging steam intothe first stage coveronly a portion of the wheel arc and are arranged to convert an amount of pressure represented by the drop in pressure between the source of, supply and the first stage compartment into velocity and to discharge the fluid against the wheel buckets. The pressure of the fluid striam at the discharge end of the nozzle may e the same as the stage compartment pressure so that the fluid acts solely by impact, or the pressure may be slightly above the stage compartment pressure so as to compensate for the losses due to the friction of-the fluid stream on the buckets. In other words there may be a slight drop in pressure of the fluid stream between the pdint where it enters and leaves the working passages of the wheel.- It is desirable to make this drop in pressure small since if the nozzle end pressure is Patented Aug. 31,1909.

materially greater than the stage compartment pressure, there will be excessive leakage through the clearances between the relativelymoving parts. the clearances in a given stage is lost to that stage because freely enters the chamber or, compartment in which the wheel is located,

provision being made to e utilize the pres-' sures on opposite-sides of t e wheel to prevent end thrust.

The velocity of the 'fluid stream is abstracted in each stage b successive opera- Any I fluid escaping through tions, suitable intermediate buckets being located between the rows pf wheel buckets to receive the fluid from one row and discharge-it against the next at .the proper angle. In the present embodiment of the invention two rows of wheel buckets with a partial row of intermediates are suflicient for the purpose, the said intermediates being located directly. in line with the nozzle. Where the velocity of the fluid stream is greater than in the present case, I may rovide a greater number of rows of wieel buckets and one or more additional rows of intermediate buckets in each stage. 'The same arrangement of parts 1s preserved 1n the later high-pressure stages, the arc. covered by the nozzle and the intermediates gradually, increasing b stages toward the exhaust to compensate or the increased volume of motive fluid due to its decreased pressure.

In one ormore of the arrangement is entirely different. Here the nozzle extends entirely around the wheel and casing and all of the buckets adjacent thereto are-active. For'normal load condithe low-pressure stages tions, the motive fluid instead of expanding partially down, the remainder of the expansion taking place in the wheel and intermediate buckets, whereby the energy of the motive fluid is converted into use ul work by the impact of the fluid on the buckets and also by the reaction of the fluid on the buckets as it flows from one row to the next. Since the nozzle end pressure is materially above that of the flllld' stream exhausting from the bucketsit follows that the flow will be-enforc'ed by an amount determined by the pressure diflerence between the inlet and the exhaust. The amount of this pressure drop, where only the initial, or the initial and certain of the later stages are governed will vary to a greater or less extent with load changes, it being greatest at heavy loads. F rom'this it follows that at moderate loads the stage or stages thus arranged will work more after the fashion of a pure impulse machine while as the load increases to a maximum the stage or stages will work more and more as a combined impulse and reaction machine. In order to effectively abstract a large proportion of the energy in the fluid stream in the low pressure stage or stages I find it desirable to provide a greater number of rows of buckets in said stage or stages than in the high pressure stage or stages.

It is apparent that with a nozzle end pressure so much higher than the exhaust pressure of the wheel that unless special provision is made there will be excessive To prevent this carried by bases supported by the turbine casing, the said bases acting to prevent the free passage of motive fluid past the wheel buckets and cause it to" flow through the bucket spaces and perform useful work by im also and reaction.

'(gbviously the arrangement described creates a heavy end thrust on the shaft because the eflective pressure on the nozzle side of the wheel is that due to the area ofthe wheel times the nozzle end pressure, while on the other side it is that due to the area of the wheel times the exhaust pressure of the stage. I prefer to partially balance the thrust due to one or more wheels by that due to one or more other wheels oppositely arranged. This construction is particularly adapted-for vertical shaft machines, since the wheel exerting the greater thrust can be arranged'in a manner tending to lift the weight of the shaft and revolving elements carried thereby, and thus relieve the step bearing. Care should be taken to so arrange the parts that the upward thrust is never quite suflicient to overcome the downward thrust and .the weight of the revolving element, the latter commonly including the rotating member of a dynamo-electric machine. In carrying out this feature of my invention a vertical shaft is provided which is surrounded by a casing divided into wheel or stage compartments by diaphragms. In the high-pressure stage compartments the direction of steam flow is downward while in the first of the low-pressure stage compartments it is upward and in the second it is downward, the two stage compartments working in series. That is to say, the steam flows first through one, then reverses and flows through the other to the exhaust. In order to provide for this change in direction of the steam in its passage through the stage compartments, the casing has vertically disposed conduits some of which receive steam from a high pressure stage compartment and supply it to one of the annular or total flow stage compartments while the remaining conduits receive fluid from the said annular or total flow stage compartment and after reversing its direction of motion with respect to the shaft discharge it downwardly to the nozzle of the last stage. By varying the pressures existing at the ends of the nozzles in certain stages for a given load condition, the'lifting effect on the shaft can be made greater or less.

The admission of fluid to the turbine is controlled by a valve mechanism under the control of a speed governor. As shown separately actuatedvalves are'employed. I may use stage valves between the high pressurestages if desired, so as to vary the number of active nozzles or nozzle sections; As the buckets in the low pressure stages have to handle a large volume of fluid, it is impracticable to make the expansion on one side only, as in the us al construction, by slanting the covers of t e buckets, because the angle is so great that the motive fluid will not properly fill the bucket spaces. To overcome this I step the face of the Wheel and also that of the adjacent surface of the casing and mount the buckets on the steps thus formed. The covers and the portions of the bases between the buckets diverge, the angle of inclination to a plane parallel with the shaft being the same in both cases.

In the accompanying drawings which are illustrative of one of the embodiments of my invention, Figure 1 is a quarter longitudinal section of a turbine having high pressure I partial flow stages and low-pressure total flow or annular stages; Fig. 2 is a cross-section looking down on the diaphragm just above the first annular stage, with certain of the parts broken away; Fig. 3 is a partial axial section showing a conduit for conveying motive fluid from one annular stage to another; Fig. 4 is a cross-section taken just above the last diaphragm; and Fig. 5 is a detail view showin a step bearing for supporting the vertical shaft.

1 represents an upright shaft having a number of high pressure disk wheels and two or more low pressure wheels 3 and 4, said wheels and shaft together forming the rotor of the turbine. The wheels 3 and 4 are provided with wide rims or drums for carrying a number of rows of buckets. The turbine wheels are inclosed by a sectional caslng and are located in stagecompartments separated one from the other by diaphragms' The upper diaphragm 5 is made somewhat smaller than the other high pressure diaphragms owing to the high pressure to which it .is subjected. It is supported by an internal shoulder 6 on the inside of thecasing, the said shoulder also containing stage nozzles 7. The casing 8 for the high pressure stages forms one section of the whole and rests on thesection 9, the latter being mounted on a base section 10 containing a chamber communicating with the atmosphere condenser or other exhaust. The base section usually but not necessarily supports the ste bearing for theshaft which takes care 0 any de sired percentage of the weight and also any excess thrust due to the arrangement of the parts. The diaphragm 11 between the high and low pressure stage compartments rests on a shoulder 12 formed on an internal projection 13 on the casing section 9. This projection contains two sets of passages or conduits 14.- and 15, the former supplying motive fluid to next to the last wheel and the latter to the last wheel. The conduits 14 receive motive fluid from the annular chamber 16 bounded by the periphery of the diaphragm and the inner wall of the upper section'of the casing and discharge it to the annular chamber 17 formed in the internal projection 13. By reason of this chamber the pressure of the fluid from the several conduits is first equalized and then fed to all of the nozzle sections.

The conduits 15 receive motive fluid from the chamber 18 formed above the first low pressure wheel and discharge it in multiple into the annular chamber 19 that is also formed in the internal projection 13 of the casing. This annular chamber equalizes the pressures of the several streams issuing from the conduits 15 and also supplies it to all of the nozzle sections of the last wheel. The casing is provided with a head 20 which supports the valve chest 21 and also the packing 22. Between the shaft and each of the diaphragms is a self alining packing 23 to prevent the escape of'fluid.

Admission of fluid to the turbine is controlled by the separately actuated valves 24, the latter acting under the control of a suitable governing mechanism. I have not illustrated the stage valves which respond automatically to pressure changes because they are not in the plane of the section. Then one of the admission valves opens it supplies fluid to the chamber 25 which in turn delivers it to one or more sections of the inlet nozzle 26. This nozzle is arranged to convert a certain amount of pressure of the fluid into velocity and discharge it against in close proximity; to the under side ofthe wheel is afsegment '29 of a rim which roughly conforms to the shape of t e wheel near the .periphery and acts to prevent the motive fluid from rebounding on a fixed part of the casing and striking the wheel in a manner to.oppose,rotation. The ring is supported from the adjacent diaphragm by upright su ports 30. The same arrangement is fol owed in each of the high -'pressure stage compartments with'the exception that the arcs covered by the nozzles and intermediates successively increase as the pressures in the stages decrease. The cross-sectional areas of the nozzles and bucket spaces increase of course to. take care of the increased volume of motive fluid at the decreased pressure.

In Fig. 5 is shown a step bearing 35 mounted in a suitable casing 36 supported by the base of the machine or other support and a guide bearing 37.

In the Curtis type of turbine, over which my invention is an improvement, provision is made for overcoming losses due to friction, eddy currents, etc. by slightly enlarging the bucket spaces over that actually required to convey the motive fluid. This en-v largement of the bucket spaces results in a small drop in pressure between the inlet and discharge of the working passage in a given stage, but this is insuflicient to perform any actual work in driving the bucket wheel s. In my improved construction, however, provision is made in the low pressure annular V or total flow stages for causing the expansion of the steam in the bucket spaces to not only compensate for the frictional retardation but actually to perform work by reason of the reaction effect as the pressure decreases step-by-step in the'bucket spaces of the wheel and intermediates. In these buckets the velocity steps are small and are also equal under predetermined load conditions.

In accordance with the provisions of the patent statutes, I have described the principle ofoperation of my invention together with the apparatus which I now consider to represent the best embodiment thereofybut I desire to have it understood that the apparatus shown is only illustrative, .and that the invention can be carried out by other,

means.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is,--

1. An elastic fluid turbine comprising a plurality of stage compartments working at different pressures, va nozzle for a high pressure stage which converts the available pressure thereof into velocity, and whose end pressure is substantially the same as that of the exhaust from the stagecompartment, wheel buckets cooperating therewith to abstractthe velocity, an annularnozzle for a low pressure stage which partially converts I plurality of stage compartments working at different pressures, a nozzle which converts the available pressure of a high pressure stage into velocity, wheel and intermediate buckets which fractionally abstract the velocity of the fluid received from the nozzle, a wheel for the buckets which is balanced as to fluid pressures, an annular nozzle for a low pressure stage which converts only a certain percentage of the available stage pressure into velocity, wheel and intermediate buckets arranged in rows, all of which are active and cooperate with the nozzle to abstract the velocity from the fluid due to the nozzle and also to alternately create ve locity and abstract it as the fluid flowstoward the exhaust, and means for causing the fluid to flow in a reverse direction through certain of the stage compartments.

3. An elastic fluid turbine comprising a plurality of stages workin at successively decreasing pressures, nozz es for the high pressure stages that convert the available pressure of each of the high pressure stages into velocity, wheel buckets cooperating therewith which abstract the energy of the fluid without imparting velocity thereto, annular nozzles for the low pressure stages which convert only a limited portion of the available pressure of each stage into velocity, wheel and intermediate buckets arranged to abstract the velocity of the fluid as received from the annular nozzles and also to'create supports cooperating. to prevent the fluid from flowing from a point of high to a oint of low pressure without passing throng the bucket spaces, and means for causing the fluid to flow in a reverse direction through certainiof the low pressure stages.

4. An elastic fluid turbine comprising a casing, high and low pressure diaphragms for dividing the casing into stage compartments, bucket wheels for the high pressure stage compartments, bucket wheels for the low pressure stage compartments havingv agreater number of rows of buckets than those of the high pressure stages, expanding nozzles for high pressure stages, intermediate buckets therefor, the nozzles and buckets covering less than the full circumference of the wheel, annular nozzles. for the low pressure stages which convert a portion only of the available stage pressure into velocity, intermediate low pressure buckets, the wheel and intermediate buckets of the low pressure stages being constructed and arranged to work by impact of the motive fluid undercertain load conditions and to work by impact and reaction under other load conditions, and means for causing the fluid to flow in a reverse direction through certain of the low' pressure stages.

5. An elastic fluid turbine comprising a 'pluralityof stages through which the motive fluid flows one after the other in series, buckets therefor, fluid discharging devices for the different stages, the buckets and said device of one of the intermediate pressure stages being reversed with respect to those of the remaining stages, a casing for the turbine, an annular chamber in the casing which is in communication with said reversed device, conduits formed in the casing which convey motive'fluid exhausting from the preceding stage to said chamber, and

' other conduits in the casing for conveying motive fluid exhausting from the reversed stage to the next stage.

6. An elastic fluid turbine comprisin a casing, diaphragms for dividing the easing into a plurality of stages each containing a bucket wheel and fluid discharging means, the motive fluid flowing through said stages in series and one of said stages being reversed in position with respect to the others, a wall within the casing surrounding the reversed stage and cooperating with the two adjacent diaphragms to inclose said stage, and conduits arranged in the space between the Wall and the casing for com ing motive fluid to and from said stage.

7. An elastic fluid turbine comprising partial flow impact stages, low pressure stages acting by impulse and reaction, nozzles for the high pressure stages that convert the available stage pressure into velocity, wheel buckets acted upon by motive fluid from the nozzles, annular nozzles for plurality of stages each containing a bucket wheel and a fluid discharging means, one of said stages being reversed in position with respect to the others, conduits formed in the casing which receive fluid from one stage,

convey it past the reversed stage in a given direction and deliver it to said means, and a second set of conduits formed in the casing and arranged in alternate relation to the first set for receiving fluid exhausting from the reversed stage, conveying it past saidstage in the opposite direction to the flow through the first set of conduits, and delivering it to another stage.

9. An elastic fluid turbine comprising a plurality of stages, each containing a bucket wheel and a sectionalized fluid dlscharging device, one of said stages being reversed in position with respect to the others, annular chambers which equalize the pressure of the fluid supplied to certain of the discharging devices, a conduit which receives fluid from one stage and discharges it into one of the annular chambers, and a second conduit which receives the fluid exhausting from the reversed stage, convey s it past said stage and discharges it into a second annular chamber.

10. An elastic fluid turbine comprising a plurality of stages, each containing a bucket wheel and a sectionalized fluid discharging device, one of said stages being reversed in position with respect to the others, annular chambers which equalize the pressure of the fluid supplied to certain of the discharging devices, a plurality of conduits which receive fluid from one stage, convey it past the reversed stage and discharge it into one of the annular chambers where the pressure of the several streams is equalized, and a second set of conduits which receive motive fluid after it passes through the reversed stage and discharge it into a second annular chamber where the pressure of the several streams is equalized.

11. An elastic fluid turbine comprising a plurality of stages, some of which are partial flow and the remainder total flow, one of the total flow stages being reversed with respect to the others, nozzles for the artial flow stages which convert the available stage pressure into velocity, nozzles for the total flow stages that convert only a portion of the available stage pressure into velocity, wheel and intermediate buckets for the partial flow stages that abstract the energy of the fluid stream without imparting velocity thereto, rows of intermediate and wheel buckets for the total flow stages that alternately convert the pressure of the fluid into velocity and abstract it, conduits for conveying fluid past the reversed stage" to the dis charging devices of said stage, and other conduits which receive the fluid exhausting from said reversed stage and convey it past said stage to the discharging devices of another totalflow stage.

12. An elastic fluid turbine comprising a casing, diaphragms for dividing into stages, one of said stages belng reversed with respect to the others to reduce the axial thrust, a set of conduits formed in the casing which convey fluid past the reversed stage and deliver it to the discharging devices thereof, a second set of conduits also formed in the casing which receive fluid exhausting from the reverse stage convey it past said stage and deliver it to the discharging devices of a stage of lower pressure.

13. An elastic fluid turbine comprising a casing, diaphragms for dividing the casing into stages, wheel buckets therefor one of which acts in a reversed manner with respect to the others, an internal projection on the casing having shoulders which support diaphragms, independent annular chambers formed in the casing which supply motive fluid to certain stages, a set of conduits formed in the projection between the shoulders and the outer wall of the casing which convey motive fluid to oneof the annular chambers and its stage, and a second set of conduits also formed in the projection between the shoulders and the wall of the easing which convey motive fluid from the last mentioned stage to another annular chamber and to its stage.

14:. An elastic fluid turbine comprising a casing, diaphragms for'dividing the easing into stages, one of which is reversed with respect to the others, an internal rojection on the casing having shoulders 0 different diameters formed on the projection to support diaphragms, the diaphragm of higher pressure being smaller than the one of lower pressure, conduits and annular chambers formed in the projection, discharging devices receiving fluid from the chambers, and wheel and intermediate buckets receiving fluid from said devices.

15. An elastic fluid turbine comprising a plurality of high pressure stages working on the partial flow plan, low pressure stages working on the total flow plan, nozzles for the high pressure stages, rows of wheel buckets therefor, nozzles for the low pressure stages, rows of wheel buckets therefor which alternately convert the pressure of the fluid into velocity and extract it, the number of rows of wheel buckets being greater in the low pressure stages than in the casing I the high, and means for causing the elastic rality of stages each provided with a nozzle,

and wheel and intermediate buckets, one or more of said stages constructed and arranged to exert a thrust in the downward direction and one or more of said stages constructed and arranged to exert a thrust in the upward direction which partially balances the combined effect of the weight of the moving parts and the said downward thrust, a vertical shaft carrying, the wheel buckets, and a step-bearing that 'takes up the remaining thrust and weight on the shaft.

18. In a turbine, the combination of stages each of which is provided with a nozzle and wheel and intermediate buckets for abstracting the velocity of the fluid by successive operations, the said stages being balanced as to end thrust, stages each of which is provided with a nozzle and wheel and intermediate buckets acting by impact and reaction to convert the energy of the motive fluid into work, the said stages being reversed with respect to each other so that the thrust of one balances the other to a greater or less extent, and a means for taking up the unbalanced. thrust.

19. A turbine comprising a stator, a compound rotor consisting of a disk wheel and drums, means for introducing the operating fluid to the operative surface of the rotor,

means for causing the whole of such fluid to flow in one direction along a portion of the length of the operative surface of the rotor, means for causing the Whole of such fluid to flow in the reverse direction along another portionof the length of the operative suri face of the rotor, and means for conveying such fluid away from the turbine.

In witness whereof, I have hereunto set my hand this 18th day of January, 1907.

WILLIAM L. R. EMMET. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

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