US800230A - Elastic-fluid turbine. - Google Patents

Description

1 PATBNTED SEPT. 26, 1905.

W. T. MIXSBLL.

ELASTIC FLUID TURBINE. I APPLICATION FILED M AY 0, 1903. RENEWED FEB. 21.1906- 3 SHEETS-SHEET 1.

I A M PATENTED SEPT. 26, 1905.

w, T. MIXSELL.

ELASTIC FLUID TURBINE. APPLICATION FILED MAY 9, 1903. RENEWED FEB. 21.1905.

3 SHEETS-SHEET 2.

- PATENTED sEPT.,20, 1905.

W. T. MIXSBLL. ELASTIC FLUID TURBINE.

' APPLICATION FILED MAY 9, 1903. RENEWED FEB. 21.1905.

3 SHEETS-SHEET 3.

Q Q I//////IIIII/A (Z "W////// ///////A sufficient pressure remains to overcome fric- UN TE B AIES' PAT T o EIoE.

WARD TEMPLE MixsELL, OF WASHINGTON, DISTRICT OF COLUMBIA.

' ELASTIC-FLUID TURBINE.

' ings, forming a part of'this specification, and

to the letters of reference marked thereon.

This invention relates to improvements in turbines, and particularly such as are designed for converting pressure of an elastic medium into mechanical power, the objects of the in vention being to secure a greater percentage of mechanical power than heretofore obtained in impulse or reaction or in combined impulse and reaction turbines with the employment of an elastic medium under pressure.

In carrying the invention into practice the greatest possible momentum is imparted to the elastic medium with the least possible reduction in pressure, the momentum is con;-

verted into mechanical energy without further reduction in pressure or increase in expan-- sion, and the pressure at which the momentum is converted into mechanical energy is again utilized to lmpart momentum to the elastic medium, which momentum is converted into mechanical energy without further reduction 7 of pressure or increase in expansion, and this sequence is repeated until practically no fur} ther pressure remains to impart momentum to the medium. 3

I have discovered in the practical application of the present invention that if the pres, sure be utilized to impart momentum to the elastic medium by reduction to a pressure be-. tween fifty and sixty-five per cent. (specifically 58 per cent.) of the absolute initial pressure(or at a rate of expansion of 1: 1.624., specifically) and the momentum be converted into mechanical energy without further red uction'in pressure or increase in expansion and these steps be repeated a number of times or until no tional and other resistances the total percentage of energy of the elastic medium which may be converted into mechanical'energy is greater than where the pressure imparts momentum to the medium by a single, quick,

Specification of Letters Patent.

Patented Sept. 26, 1905.

Application filed May 9, 1903. Renewed'February 21, 1905. I Serial No. 246,778.

therefore, be contrasted with that type of turbine wherein the steam or other elastic medium is reduced .in pressure and expanded continuously or that type of compound turbine wherein the steam or elastic medium is" carrying into effect the method above set forth,

but may be utilized to good advantage in many types of turbines where simplicity, compactness, and a uniform and eflective control are desired.

In the structure illustrated the several movable elements or sets of vanes are mounted on a common shaft; but each is in a separate chamber, the chambers being formed by subdividing a relatively large casing or chamber, the several chambers being connected by passages controlled by a valve, whereby all of the passages may be simultaneously opened or closed.

In the accompanying drawings, Figure l is a vertical section through a turbine embodying the present improvements. Fig. 2 is a section on the line 2 2 of Fig. 1. Fig. 3 is a diagrammatic view of a preferred form of vane. larger nozzles. Fig. 5 is a diagrammatic View illustrating the proportional increase in the diameter and length of the orifices of the noz- Like letters of reference in the several fignres indicate the same parts.

In the apparatus illustrated a casingA is provided preferably an integral casting, having a cylindrical interior chamber somewhat larger in diameter than the'diameter of the vanewheels and having at one side avalve-chamber B, which for convenience of construction is tapering or conical, with the larger end toward the exhaust end of the turbine, wherebyithe valve may be ground, to a seat. The cylin Fig. 4 is a detailed view of one of the drical chamber of thecasing A is subdivided into smaller chambers by partitions O, preferably driven into the same steam-tight and each having a pro ecting annular peripheral titions are properly spaced and positioned, it being a comparatively easy matter to regulate the size of the chamber by making the wall 0 of greater or less width. A lining-diaphragm D is preferably provided on the inner side of each of the partitions, between which and the partition a packing D, of nonconducting material, is held to prevent loss of heat by radiation, and the casing may be jacketed for the same purpose. Each partition is formed with a central bearing, preferably having a conical seat (Z, in which fits a correspondingly-shaped journal E. The journals are all mounted on the drive-shaft F, preferably being held by friction and suitably packed by packing Gr, held in place in the journal by a gland g. The journals can move longitudinally on the shaft and will be so moved by the steam-pressure until each finds its seat in its bearing; but the packing will create sufiicient friction to insure the turning of each journal with the shaft. The journals will seat steamtight in their bearings, and the packing will prevent the leakage of steam along the shaft inside of the journals.

The turbine-Wheels H, having the vanes h I thereon, are located one in each of the chamance with the center of the shaft as an axis it is the design of the present construction to provide a means whereby they may find their own centers when rotating, and to permit of this there is interposed between the hub of the 'Wheels and the journals a sleeve, bushing, or

equivalent connecting means K which will yield or be slightly elastic--as, for instance, asbestos fiber. The hubs of the Wheels may, if desired, be slightly conical or threaded for holding the sleeves or bushings, and the journals may be correspondingly formed. The Wheels may be connected with the shaft by pins or other means, which will permit the journals to seat properly in their bearings independently of the wheels and the wheels to find their proper centers of rotation. As shown in the drawings, pins L pass through the wheel-hub and into the shaft with suflicient play in the shaft to permit of the results stated. The vanes are preferably of the crosssectional shape shown in Fig. 3 t'. e., the inner and outer surfaces are arcs of circles eccentric to each other. Thus the periphery of the wheels may be made in the form of thick rims and the vanes cut therefrom by simple mechanism, the capacity being governed by the depth or width of the rim and depth of the cuts. After the vanes are formed a cover plate or ring M may be secured over their ends to properly direct the steam or elastic medium through the vanes, inasmuch as acousiderable space is preferably left on the inner and under sides of the same, as shown in Fig. l. The admission-nozzles for directing the steam or elastic medium against the vanes are indicated by the dotted lines N to N, inclusive, Figs. 1 and 5, one of said nozzles, that lettered N, being shown in cross-section in Fig. 2. They are set at a slight right angle to the periphery of the wheels. Thus, as shown, the angle of the nozzles and the set of the vanes are such as to avoid friction against the rear faces of the vanes and to secure the maximum effect in bringing the steam or elastic medium to a state of rest as it leaves the vanes, whereby practically its entire momentum is imparted to the rotating wheel. Said nozzles, which will be hereinafter more speeifieally described, are supplied through passages O, leading from the valve-chamber, and said passages communicate through parts in the valve with supply-passages, the first one, 0, leading from the source of pressure-supply and the others, from the next preceding chamber, as shown clearly in Fig. 1. The elastic medium will thus flow through the valve and first nozzle into the first chamber, thence through the valve and second nozzle into the second chamber, and so on through all of the chambers, and finally to exhaust. With this construction a movement of the valve will control or cutoff the pressure from all of the wheels alike and will maintain pressure in all of the chambers save the last, and if no condensation has taken place in the interim when the valve is reopened a simultaneous'torque is developed by all the wheels instead of a successive action and loss in refilling the chambers, as would be the case if a valve for controlling the flow to or from a single one of the chambers were employed. The bore or passages through the nozzles are preferably cylindrical, and the nozzles are usually of smooth refractory metal, such as nickel, driven into the passages in the casing, the latter passages, for convenience, being drilled in from the outer side of the casing and subsequently plugged. A branch leading from the valve-chamber and all of the passages both in the valve and casing are of such capacity as not to restrict the flow from the pressure-sumily or from the chambers to the nozzles. The area and length of the restricted passage in each nozzle control, first, the momentum imparted to the elastic medium as it leaves the nozzle, and,

secondly, the relative pressure in adjacent chambers, and consequently the relative pressure which can be available for imparting momentum to the elastic medium. The nozzles are so proportioned relatively to each other as to permit onlyof a reduction in pressure to between fifty and sixty-live (preferably approximately fifty-eight) per cent. of the absolute initial pressure, and for this purpose not only may the pressure in the generator be considered the initial pressure, but

the pressure in each chamber may be considered as the initial pressure in so far as the next succeeding nozzle and chamber are concerned.

' The proportions may be determined by calculation, thus: The increase in diameter of the succeeding nozzles should be as the square root of the ratio of expansion, which at fiftyeight, per cent. reduction is approximately on throughout the series.

1.624, so that the succeeding nozzles to dis charge a similar volume at the reduced pres' sure should be as 1:1.275,1.275 being the square root of 1.624. For instance, if the first nozzle is one inch in diameter the second should be approximately 1.275 inches, the third approximately 1.624 inches, and'so With this rate of reduction in pressure or expansion of the elastic medium the greatest momentum may be imparted to the medium with the least possible reduction in pressure, and it is utilized with the greatest efliciency and economy by making the restricted passages of the nozzles of such length without enlargement or contraction that the expansion or reduction in pressure occurs before the medium leaves the said passage, no further expansion or reduction in pressure occurring during the impact of the medium against the reaction-wheel or in its passage through the vanes, subsequent reduction in pressureor expansion only taking place in the next succeeding nozzle'. The length of the passage in the nozzle is therefore such that the elastic-medium is delivered to the reaction-wheel at the moment when the greatest momentum has been ac.-

quired by the medium and before its acquired aperture.

momentum has been lessened by frictional resistance against'the wall of .the nozzle. The length may be determined empirically or by calculation and should be approximately 1.624 times the diameter of the nozzle- To prevent eddying or consumption of energy by friction, the approaches to the nozzles should be curved in accordance with the well-known laws governing the flow of one pound of steam at a velocity of four-- teen hundred and forty feet per second, as is obtained by a fifty-eight-per-cent. reductionthrough each nozzle delivered on the vanes of the wheels equal to thirty-two thousand two 6' hundred and thirty-eight foot-pounds,-(theoretically,) the total for six expansions, being one hundred and ninety-three thousand four hundred and twenty-eight foot-pounds, oratthe rate of 10.24 pounds of steam per horsepower per hour, or this same engine can utilize steam at one hundred and fifty pounds pressure absolute, with the same efficiency re- :ducing the pressure throughsix expansions,

as one hundred and fifty to eighty-seven, &c., pounds, generating the same energy-one hundred and ninety-three thousand four hundred and twenty-eight foot-pounds, as in the-former series of expansions from three hundred and ninety pounds absolute to atmospheric pressure. Thereas'on thatfifty-eight-per-cent. reduction of pressure induces such a high velocity for the diiference of pressure isthat the maximum "pressure that will exist in a I nozzle isfifty-eight per cent. of the initial pressure for any reduction of pressure ex-- ternal to the nozzle of fifty-eight per cent. or less. Consequently it becomes necessary when a ,greaterrate of reduction is employed to make the nozzle outwardly diverging, so as 'toincrease the specific area of the nozzles,

mentum of a single velocity, which might be acquired if the initial velocity could be augmented proportionately to the absolute ratio of expansion.

Fig. 5 shows approximately the proportions of the nozzles for? six expansions of the steam, and from this figure it will be seen that each nozzleis of the same proportions, and throughout its effective part the Walls are approximately cylindrical.

Inasmuch as efiiciency requires that the di-v ameter and length of the nozzles should be coordinated-and as'it is impracticable to vary; these dimensions uniformly and in unison, separate sets of nozzles are preferably provided forgiving the diiferentpowers desired and a reverse set or sets of nozzles may beprovided for reversing the'direction of rotation of the reaction-wheels." Thus in Fig. 2 it will be seen that a second set of nozzles -O is providedof less length and diameter than the first set, and consequently delivering a less weight of steam in aiigiven time, although IIO the pressures in the "generator and several chambers will remain as before. The valve has its passages so disposed that one set of nozzles is cut out and the other in when it is desired to vary the power, and consequently thesteam will be used at the highest eificiency throughout the whole range of expan- 'sion' regardless of whether the mechanical ment of as many nozzles as desired, avoids any complication of ducts for the reception of the steam passing from the vanes, and also prevents loss due to the escape of pressure between nozzles and vanes, as such pressure combines with that in the chamber and is available in the next nozzle of the series.

It will be particularly noted that the mechanical construction is exceedingly simple and compact, and the bearings are self-adjust ing in that the journals are held to their seats by the pressure in the chambers, and wear will not cause .a leakage from a chamber of higher into a chamber of lower pressure.

The upper surfaces of the partitions C are preferably slightly convex, so as to permit the water of condensation to stand around the shaft-bearings for the purpose of lubrication. The inclination is preferably very slight, as will be seen by reference to Fig. 1, where the top surfaces of the partitions are slightly lower at S than at S.

Having thus described myinvention, what I claim as new, and desire to secure by Letters Patent, is

1. In an elastic-fluid turbine, the combination of a series of relatively short substantially cylindrical nozzles adapted to receive the elastic fluid in succession, the relation of the length to the diameter of the aperture of each nozzle being uniform in all the nozzles to permit of uniform reductions of pressure in the nozzles, the succeeding nozzles in the series being of increased length and increased diameter to impart uniform velocity to the same weight but increased volume of the elastic medium, a separate chamber of relatively large capacity for receiving the discharge from each nozzle and from which the elastic medium is delivered to the next nozzle of the series and a set of movable vanes in each chamber against which the elastic medium is delivered by the nozzle for converting the momentum of the medium into mechanical energy; substantially as described.

2. In an elastic-fluid turbine, the combination with a series of chambers of successivelyincreasing capacity, a set of movable vanes located in each chamber for converting the momentum of the elastic fluid into mechanical energy, of relatively short substantially cylindrical nozzles located in position to direct the elastic fluid against and through between the vanes into the chambers, the relation of the length to the diameter of the aperture of each nozzle being uniform in all the nozzles to permit of uniform reductions in pressure in the nozzles, the succeeding nozzles in the series being of increased length and increased diameter to impart uniform velocity to the same weight but increased volume of elastic fluid, adjacent nozzles of the series respectively one discharging into and the other receiving the elastic medium from the same chamber; substantially as described.

3. In an elastic-fluid turbine, the combination with a series of chambers of successivelyincreasing capacity, a set of movable vanes located in each chamber for converting the momentum of the elastic fluid into mechanical energy, of nozzles located in position to direct the elastic fluid inwardly into said chambers and against the movable vanes, the relation of the length to the diameter of the aperture of each nozzle being uniform in all the nozzles to permit of uniform reductions in pressure in the nozzles, the succeeding nozzles in the series being of increased length and increased diameter to impart uniform velocity to the same weight but increased volume of elastic fluid, a passage extending from each chamber through a valve to the next nozzle of the series, said passages being of greater capacity than the nozzle to which it extends; substantially as described.

4. In an elastic-fluid turbine, the combination with a series of nozzles adapted to receive the elastic fluid in succession, the relation of the length to the diameter of the apertures of each nozzle being uniform in all the nozzles, the succeeding nozzles in the series, being of increased length and increased diameter and separate sets of movable vanes for converting the momentum of the fluid into mechanical energy, of a second and correspondingly-proportioned series of smaller nozzles for delivering decreased volumes of elastic fluid but at the same velocity to the vanes and valve mechanism for simultaneously cutting out or in all of the nozzles of either series; substantially as described.

5. In an elastic-fluid turbine, the combination with the casing having the cylindrical interior, the series of diaphragms having peripheral flanges, fitting in said casing and resting one on the other to form a series of chambers, and vaned wheels located in said chambers on a shaft common to all the wheels, of an inwardly-directed nozzle opening into each chamber and a passage leading from each chamber remote from the vanes to the nozzle of the next succeeding chamber; substantially as described.

6. In an elastic turbine the combination with the series of chambers, a shaft extending through said chambers, a vaned wheel on the shaft in each of the chambers and a cone-journal for the shaft in each of the chambers on the side toward the adjacent chamber of lower pressure and held to its seat by the pressure of the elastic fluid in the chamber; substantially as described.

7. In an elastic-fluid turbine the combination with the series of chambers shaft passing through all of said chambers, vaned wheels mounted on said shaft and nozzles for directing the elasticmedium against the vanes and into the chamber, of cone journals for the shaft having their bearings in the walls of the chambers and capable of a movement longitudinally of the shaft, whereby each journal is held to its seat and escape of fluid prevented by the pressure Within the chamber; substantially as described.

8. In an elastic-fluid turbine, the combination with the series of chambers, shaft'passing through all of said chambers, vaned wheels v mounted on said shaft and nozzles for directing the elastic fluid against the vanes and into the chambers, ofcone-journals having bearings in the walls of the chamber, and packing interposed between the journals and shaft, said journals being movable longitudinally independently of the shaft and of each other; substantially as described. 7

9. In an elastic-fluid turbine the combinati'on with the series of adjacent chambers for receiving the fluid successively, a shaft extending through said chambers and a vaned wheel in each chamber mounted on the shaft, of a journal movable longitudinally on the shaft located in each chamber and having a bearing in the wall of the chamber toward the next succeeding chamber of the series; substantially as described.

10. In an elastic-fluid turbine the combinationwith the series of adjacent chambers located one above the other and having their bottom walls inclined toward the center, of a vertical shaft extending through said chambers, and journaled in said chamber-walls,

vaned wheels on the shaft, inlet-nozzles forv directing the elastic fluid against the vanes and passages for the discharge of the elastic fluid; substantially as described.

WARD TEMPLE MIXSELL.

Witnesses: I

ALEXANDER S. STEWART, MELVILLE D. CHURCH.

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