US 1213889 A
Description (OCR text may contain errors)
I} F. LAWACZECK. TURBINE PUMP.0R COMPRESSOR.
APPLICATION FILED MAR. 28. I913. I
R Patented Jan. 30
FRANZ LAWACZEOK, 0F HALLE-ON-THE-SAALE, GERMA NY.
I TURBINE PUMP 0R COMPRESSOR.
Application filed March 28,
To all whom it may concern:
Be it known that I, FRANZ LAWACZECK, a subject of the King of Prussia, and residing at Halle-on-the-Sziale, Germany, have invented certain new and useful Improvements in Turbine Pumps or Compressors, of which the following is a specificationx Experience in the building of turbine. pumps shows that the eificiency of a rotor, or blade wheel, is much better in proportion as a greater part of the total energy transferred to the water (or other pumped fluid) by means ofthe rotor, exists in the form of potential energy at the outlet of the wheel, that is, the smaller the proportion of kinetic energy at the outlet of the rotor, because comparatively great losses are incident to the transformation of velocity into. pressure outside of the rotor wheel by .means of the so-called'distributer or diffuser. It is because of this fact that the impeller blades of centrifugal pumps are commonly bent backward so as to reduce the outlet velocity, although this shape, as compared with forward-bent blades, necessitates for a given discharge head, an increase of peripheral velccity of the rotor and ani-ncrease of the so-called outer wheel friction losses.
The-structure of the present invention attains great proportional potential energy at the outlet ofthe pump, and at the same time relatively small outer wheel friction losses. Fundamentally this structure is characterized by admission of the fluid at the peripliei'y of the rotor wheel and its central discharge, the impeller blades of the pump being so arranged as to increase the energy of the centripetally flowing impelled fluid. In sucha pump the absolute value of the outlet velocity can always be very small, since the most essential component of this velocity,the inner tangential velocity of the wheelis always much smaller thanthe outer. Because of this reduced outlet velocity, the kinetic energy of the discharge stream is likewise small, and a relatively simple difl'user suflices to transform the remaining kinetic energy of the stream into pressure. Indeed the diffuser may be dispensed with altogether, in machines constructed according to the invention if the stream leaving the wheel is directed radially.
The extent to which the characteristic peripheral admission feature of the invention makes-it possible to lessen the wheel friction Specification of Letters Patent.
I Patented Jan. 30, 1917. 1913. Serial No. 757,314.
will be apparent from the following considerations velocity of the fluid at the periphery of the blade wheel (whether directed inwardly or,
outwardly does not matter), and let its inclinatlon to the tangent to the periphery be denoted by a, the peripheral velocity of the wheel by u, the effective head. by H, the efficiency by n, the reciprocal of the efficiency, or l/n by e and the forceof gravity by 9. Then according to the fundamental equation of the turbine under the condition of a radially directed (inward or outward) absolute velocity of the fluid at the inner circumference of the wheel opening.
Y (5 11:1140. cos. a.
In the normal pump with central admission '10. cos. a-is always dependent to a very considerable degree upon the circumferential velocity u; for the design of the pump there is not much room left for the choice of the size of w. cos. a. Practically speaking, w. cos. a is about equal to u; greater than u with forward curved wheel blades and smaller with backward curved blades. In any case, however, and that is important,
in the-design of a pump haying peripheral.
front surfaces of the wheel) may be diminished at will without any loss of head. This effect can also be explained as a consequence of the opposing motion of the incoming stream and the circumferential velocity of the wheel. By the opposing motion of the stream entering with the velocity to the circumferential velocity of the wheel seems to be increased in relation to this stream, whereas the water particles streaming along the outside of the wheel can only produce a friction which corresponds to the real circumferential velocity u. Naturally also for-low heads the values u and w. cos. a can be chosen entirely independent of each other. The advantages of this and altogether those of the principle of the outer admission are especially noticeable in cooling Let w denote the absolute possmie, to sup water pumps for the condensation of large steam power plants. It is a criterion of those cooling water pumps that they have to deliver large quantities of waterat small heads (30 to 40 ft.) In such cases it is very desirable that these pumps should not be driven by an electric motor, but, for instance by a steam turbine, so that their working remains independent of the current generated by the power plant. In view of the high number of revolutions of the steam turbine and of the low head demanded, the diameters of the wheels, with central admission, must be chosen so small that the surplus of head, arising in any case with wheels with central admission, becomes as small as possible. As a rule, this surplus of head, which must be throttled, is economically quite inadmissible; besides the inner mouth of the wheel becomes so small on account of its necessarily small outer diameter, that in view of the low suction velocity, restricted because of the danger of tearing the suction column. only a very little quantity of water can be delivered bv each wheel, and for this reason several blade wheels (as a rule about 10) must be connected in parallel to handle the usually very great quantities of water. This circumstance has until now made it simply impossible to make use of the steam turbine. so that it has usually been necessary to use three phase induction motors with not more thanl450 R. M., in which case because of the still comparatively very large number of revolutions as many as 5 wheels mayv have to be connected in parallel. The peripheral admission of the invention does away in one stroke with all these ditficulties. Independently of the peripheral velocity it any desired head, no matter how small, can be obtained without throttling. Above all, however, the quantity of water which can be delivered by one wheel i's practically unlimited, since the suction section. which now lies in the outer circumference of the blade wheel and therefore can be made of any desired size, may always be so chosen that the suction velocity does not overstep the admissible value; whereas the quantity of water passing through the blade wheel can leave the small section of the inner mouth at any desired speed generated at will in the blade wheel. In the case of the usual blade wheels with central admission, as has been mentioned, the conditions in the case of large quantities of water are on the contrary as unfavorable as possible, for in this case the comparatively small inlet mouth of the blade wheel is available to ti incoming necessarily slow flowing water the suction secision, whereas at the same time the very rapidly outflowing water passes throu largest section of the I now it has been 1 7 pecially the bladewheels for them, for large quantities of water at small resistance heads and high number of revolutions, with the new wheel with the peripheral admission the quantity of water whicha single wheel can deliver independently of the pressure head to be generated is practically unlimited.
The wheel friction depends not only upon the velocity u but also, as we know, upon the size of the moistened outer surface of the wheel. This surface is mainly composed of the outer front surfaces of the rotor wheel. In the usual form of the wheels these surfaces cannot be diminished. If, however, a wheel of the so far usual form, 5. e., one working with central admission, be combined with a wheel which according to the invention has peripheral admission, the one front surface of the usual wheel producing the friction is thus made somewhat smaller, at the same time, however, the head attainable'with such combination wheel is about doubled. In this arrangement the water is inverted after having passed through the familiar wheel with central admission and is led from theoutside to the second set of blades fixed on the same wheel body. In this manner the harmful surface of the wheel becomes, as mentioned, a little reduced, the useful work, however, is at the same time essentially increased. In consequence, the efficiency of the rotor as a whole is also considerably raised.
In the drawings, which illustrate single stage and multistage pumps embodying the invention and in which blade wheels having central admission are combined with the characteristic wheels having peripheral admission, l igure 1 is a section through a turbine piimp according to the invention with a single wheel of combination form. Fig. 2 shows a section through a pump with an inner difluser, Fig. 3 shows one mode of execution of a multistage pump wheel without inner diffuser, and Fig. 4 another similar form with inner diffuser. Fig. 5 is a radial section through a pump with a special form of theouter diffuser, and Fig. 6 is a section on AA of Fi 5.
The single stage pump of Fig. 1 has a blade or rotor wheel a driven in usual manner'by the shaft 6. The water or any other form (even gaseous) fluid is admitted to "the pump by the stand pipe 0 and in the example shown flows first into the usual set of blades d in direction or" the arrow, 0., from the inside or center of the wheel. The water or other fluid, after having been inverted in the diffuser e wherebv its velocity. as hereinafter will be more 'fully explained may have been partly transformed into 111. 5 sure, is admitted from the outside, periphery of the wheel, to ti a' other front r "i "'7 is c. noel.
fluid now flows through these blades i from the outside to the central outlet and leaves the pump by the pressure stand-pipe g. If an especially high head is to be attained by such single stage pump, then the set of wheel blades with peripheral admission must be so chosen that the water or other fluid does not flow out radially. In this case, the kinetic energy remaining in the discharged water is converted into pres- ;1.)1re in a centrally situated diffuser h (Fig. shown in this Fig. 2'does not differ from that of Fig. 1. Naturally the pump shown in Fig. 1, as well as that shown inFig. 2,
can be constructed as multistage pumps, so that the water or other fluid to be delivered flows through several blade wheels.- One example of this multistage form of a pump according to Fig. 2 is partially shown in Fig. 4. On a common shaft b are situated the different blade wheels a a and so on,
which are alternately arranged for central Between each and peripheral admission. set of blades with peripheral admission and the following set of blades with central admission there is placed adiffuser h, which transforms the kinetic energy, inherent in the fluid as it leaves the blades 7', into pressure and which at the same time deflect the fluid in the desired manner to enter the blades d i As the wheel with peripheral admission always occupies the space which in the form of pumps at present generally used is necessary for leading back the, water from the diffuser of one wheel to the suction mouth of the following wheel, the head generated by a pump built according to this invention of equal total length with the usual pumps will be about double that of the latter; or else for the same results the total length of the pump is reduced to about half by using the new sets of blades with peripheral admission.
The multistage pump of the invention has special advantages in those cases in which, instead of producing the highest possible pressure head per blade by means of the usual diffuser, this diffuser is omitted and the wheels with alternately central and peripheral admission are united to one single wheel drum, for instance, in the manner shown in Fig. 3. This form has the advanta ge in spite of the use of a very weak shaft of giving awheel body so strongly braced that its critical speed is an extremely high one.
A further advantage of this construction will be seen in that the blade whee s at 2' and (Fig. 3) can be cast open and consequently can be easily tooled. The two sets of blades then. are covered by the doublecone m, which can also be very easily and completely tooled. such wheel body is to A. .eL
For the rest the form of the pump face becomes an axial plane; then more work is transferred to the water by the blades is before it reaches the bar than by the blades 5 following the bar. I
It is a further advantage of this construction that by the omission of sleeves which till now have been placed between the several stages and which have: the tendency to strike the turning shaft, the safety of working is essentially increased. If the clearance-pressure, as will be now fully described, on the outer periphery ofthe wheelbodies a is made constant for both sets of blades i and it; of each wheel,then the num ber of spaces to be tightened is reduced to half of that of usual pumps. For this purpose the outer diffuser 6 (see for instance Figs. 1 and 2) simply could be formed so that the velocity of the water produced in a set of blades with central admission is inverted without transformation into pressure, and is transferred immediately into the second wheel. This procedure would, however,
sometimes be impractical, since, as expenarrow space. To avoid this loss it is advantageous to convert the kinetic energy inherent in the water leaving the blades with central admission into pressure and to then invert the water after its velocity has become small enough. If this water, being under pressure, should-be directed immediately to the followingset of blades (f or k), the inconvenience of a considerable clearance pressure at the periphery of each wheel a would arise. The invention avoids this inconvenie'nce by bringing the pressure of the inverted water before its entrance at the periphery of the wheel, as closely as possible to the pressure of the water leaving the wheel ((1 or i) with central admission. The outwardly situated diffuser of this kind may be so constructed, that the diffuser, for instance, e of the drawing, first transforms in the usual manner the water velocity into the same time its velocity is increased to the required value. This double deflection of the water can be avoided, as shown in Figs. 5 and 6, by transforming the absolute velocity of the fluid .leaving the wheel having central admission, into pressure, deflecting the fluid and again transforming pressure into the initial velocity, all in the same plane. The absolute velocity of the fluid leaving the set of blades 2' of the blade wheel a is transformed into pressure in the nozzlelike part 7) of the diffuser 1'. The deflection is effected in the part 8, the fluid preferably being still under the guidance of the directing blades used in the part 72. Thus the fluid keeps its low velocity to the point t shortly before its entrance into the blades k of the wheel a. At this point t, where short guiding blades may be placed for securing the direction of entrance again, it is expedient that the fluid regain the same velocity it had at entrance into the diffuser 1". To guide the water entirely in the same plane situated in the direction of the absolute outlet velocity at the periphery of the wheel gives the lowest losses.
The pump or the invention may naturally also be used for delivering or compressing gaseous media after having been correspondingly altered.-
1. A turbinepump or compressor having a rotor with one set of impeller blades associated in the usual manner with a central inlet and peripheral outlet, another set of impeller blades arranged between a peripheral inlet and central outlet and adapted to increase the energy of the centripetally impelled fluid and a diffuser adapted to receive the discharge from the first set of blades, transform kinetic energy thereof into pressure, and subsequently invert the fluid for passage into the inlet of the second set of blades.
2. A turbine pump or compressor having a rotor with'one set of impeller blades associated in the usual manner with a central inlet and peripheral outlet, another set of impeller blades arranged between a peripheral inlet and central outlet and adapted to increase the energy of the centripetally impelled fluid and diffuser adapted to recci've the discharge from the first set of blades, transform kinetic energy thereof Into pressure, subsequently invert the fluid, and then increase. the velocity and reduce the pressure of the fluid as it passes into the inlet of the second set of blades.
3. A turbine pump or compressor having a rotor with one set of impeller blades associated in the usual manner with a central 'inletand peripheral outlet,.another set of impeller blades arranged between a peripheral inlet and central outlet and adapted to increase the energy of the centripetally impelled fluid and a diffuser adapted to receive the discharge from the first set of blades, transform kinetic energy thereof into pressure, subsequently invert the fluid, and then increase the velocity and reduce the pressure of the fluid as it passes into the inlet of the second set of blades, and directing vanes in the diffuser adapted to direct the entering water in the manner described.
4. A turbine pump or compressor having a rotor with one set of impeller blades associated in the usual manner with a central inlet and peripheral outlet, another set of impeller bladesarranged between a peripheral inlet and central outlet and adapted to increase the energy of the centripetally impelled fluid, and a diffuser adapted to receive the discharge from the first set of blades, transform kinetic energy thereof into pressure, subsequently invert the fluid in the same plane, and then increase the velocity and reduce the pressure of the fluid as it passes into the inlet of the second set of blades, and directing vanes in the diffuser adapted to direct the entering water in the manner described.
5. A turbine pump or compressor having a rotor witlpone set of impeller blades associated in the usual manner with a central inlet and peripheral outlet, another set of impeller blades arranged between a peripheral inlet and central outlet and adapted to increase the energv of the centripetally impelled fluid, a stationary chamber arranged to receive the discharge from the first set of blades and invert it for passage into the inlet of the second set of blades. and vanes in said chamber adapted to direct the fluid as it passes into the said inlet.
In testimony whereof, I aflix my signature in the presence of two witnesses.
Witnesses N. R. SNYDER, DORIS KRAHL.