US2022682A - Vacuum pump - Google Patents

Description

Dec. 3, 1935. D. McDoNALD 2,022,682

VACUUM PUMP original Filed Jan. s, '195s 2 sheets-sheet 1 D. MGDONALD Decn 3, 195s.

VACUUM PUMP Original Filed Jam..l 3, 1935 2 Sheets-Sheet 2 R. m m V m a vacuum at the intake for said fluid medium, and discharging the fluid medium from the rotor at a pressure sufilcient to overcome external rei densed and collected in a closed housing which surrounds the rotor. f

The closed housing of the pump is shown at I, and a rotor is suspended therein from a shaft 2 which is journaled in the housing for rotation by a. motor 3 mounted on the housing. The rotor lcomprises a support for the inducing jet, and may consistvof vertically spaced discs 4 5, meeting at their outer peripheries as shown at 6 and with the center of the lower disc preferably having a depending annular collar forming an inlet 1. An intake pipe 8 projects upwardly into housing I in alinement and communicating with inlet 1; and a. liquid seal is provided between the stationary intake pipe and the rotor, and may be of the form disclosed and claimed in my co-pending application Ser. No. 639,627, led October 26, i932.

As an instance of this construction a bowl I0 may be 4suspended from disc 5 for rotation with the rotor, and a flange II may project laterally from the upper end of stationary pipe 8 in restricted vertically spaced relation below the disc 5 and just clearingr the inlet collar 1. The base of the bowl forms an inlet for fluid; and when the pump is in operation, with the bowl I0 turning with the rotor, fluid is forced upwardly by centrlfugal force along the inclined wall of the bowl and fills the outer peripheral portion of the space between flange II and disc 5, so as to provide a liquid seal surrounding the intake pipe 8. y The fluid which is forced upwardly by centrifugal force at the periphery of bowl I0, constitutes the motive fluid for the inducing jet which is mounted between discs 4 5; and the inducing jet preferably comprises a plurality of units of similar construction and preferably equidistantly circumferentially spaced and each comprising one or more jet elements. Each unit is shown as having a nozzle I2 mounted between the discs 4 5 with its bore I3 communicating at its lower end with the outer peripheral portion of bowl I0, and its outlet I4 opening radially outwardly into the space between discs 4 5. The motive fluid which is discharged through outlet I4 thus provides a jet action for entraining and ,radially impelling the uid medium which occupies the enclosed space between the discs 4 5 and surrounding the nozzles I2, and since this space is open to intake pipe 8 via the inlet collar 1, the entrained and radially impelled fluid medium reduces the pressure at the' intake pipe, so that with the motive fluid impelled at high velocity, and thereby entralning a large volume of the surrounding fluid medium and radially impelling the same at high velocity, the pressure at the intake 8.may be so lowered as to produce a high vacuum.

The centrifugal forceresulting from rotation of the rotor discharges the motive fluid through jet I4 at the desired velocity for entraining the surrounding fluid medium, and circumferential slippage of the rotating motive fluid may be decreased by impellers which are adapted to turn with the rotor. In the present embodiment, such impeller blades I5 are suspended from the disc 5 in the restricted vertical space between the rotor 5 and the flange II, the blades being circumferl entially spaced as shown in Fig. 2; and when the rotor is turned, the fluid which has been elevated in bowl I0 by centrifugal force, is thus forced radially outwardly through the jet I4.

When the motive fluid discharged from jet I4 has entrained the fluid medium from the surrounding space, the combined centrifugal flow is accelerated since the kinetic energy ofthe motive fluid is maintained by the centrifugal force resulting from continued rotation of the flow, thereby insuring high velocity of flow and entrainment of a large volume of the fluid medium; and the jet action is preferably compounded so that the kinetic energy of the motive fluid is utilized to its 20 maximum for entraining and impelling the surrounding fluid medium. As an instance of such compounding, a series of successive nozzles I6 are mounted between the discs 4 5 for cooperation with each of the jets I4; and the jet I4 discharges 25 into the flaring mouth of a combining tube I1 which tapers toward its outer end so as to form one of the nozzles I6, with each of the series of nozzles in turn discharging into the flaring mouth of the next succeeding combining tube. The fluid 30A discharged at each succeeding nozzle thus provides the motive uid whereby the fluid medium in the space between discs 4 5 is entrained at the flaring mouth of the next combining tube; and as a consequence the kinetic energy of the motive fluid, maintained by the centrifugal force resulting from rotation of the fluid, is successively expended at the multi-stage inducing Jet, for entraining a large volume of the fluid medium from the space between discs 4 5, and discharging the entrained fluid at high velocity.

The entrained fluid is directed along the normal path of travel of a rotating mass so as not to obstruct centrifugal discharge of the fluid;

and for this purpose each series of nozzles I6 is 45 curvilinear, and preferably defines an involute as shown in Fig. 2. As shown in Fig. 4 the series of nozzles may be formed by spirally twisting an elongated metal strip so that each convolution of the spiral tapers from the flaring mouth of a combining tube I1, to its opposite end which forms the restricted discharge orifice of a nozzle After compounding the jet action bythe multi-stageV inducing jetthe entrained flow is discharged from the periphery of the rotor; and the flow is preferably cross-sectionally restricted as it approaches the periphery of the rotor, so that it may be compressed for discharge at a pressure adapted to overcome external resistance. For this purpose the multi-stage jet terminates short of the outer periphery of the rotor, with the last nozzle I 6 preferably opening into an annular ring 20 which is mounted between discs 4 5; and a compression tube 2I which is mounted between discs 4 5, communicates with the last nozzle I6 at the ring 20, and extends to and opens through the outer periphery 6 of the rotor, with the tube continuing the involute of the multistage jet and tapering slightly toward its outer end which discharges externally of the rotor as shown at 22. The annular space between discs- 4 5 from which the uid medium is drawn Into thel multi-stage jet is thus closed at' its' outer peripheryby ring 20, so that suction resulting Cil aoaaeee 3 :from entrainment of the fluid medium reduces the pressure in the enclosed annular space for creating a vacuum at intake pipe ii; and the entrained fluid is compressed and discharged through the involute compression tube di so there is no resistance to ilow oi the duid along the normal path oi travel of a rotating mass,

and the :fluid is discharged under pressure from the compression tube into the surrounding housing i.

`The invention thus provides an elector for entraining a fluid medium by a motive rluld, so as to reduce the pressure at the intake for the :fluid medium and build up pressure at its discharge.

with the kinetic energy for the motive fluid produced by the centrifugal force resulting from rotation oi a rotor on which the inducing iet is mounted, and the inducing jet comprising a multi-stage jet whereby the centrifugal force of rotation maintains the kinetic energy of the motive duid for use at the successive jets, in order that its maximum energy may be utilized for entraining and irnpelling the :duid medium, thereby entraining such volume of the fluid niediinn and compressing the same and discharging it at such velocity as to respectively produce an appreciable vacum and an appreciable pressure at the intake and discharge of the rotor. Any suitable liquid may be employed as the inotive iiuid; and the invention is pamicularly adapted to pumping a duid medium such as a readily compressible gas, since such an entrained duid may be readily compressed at the successive jets, and thus insure eicient operation when the ejector is compounded to an appreciable plurality oi stages adapted to entrain such volume oi gas and impel the same at such velocity as to provide .a pump oi large capacity and adapted to produce a relatively high vacuum.

When the pump is employed ior withdrawing vapors through intake the entrained vapors which are compressed in tube 2i are 4to a large measure condensed in said tubebeiore discharge from the rotor into the closed housing i; and pressure is built up in the closed housing ior condensing any remaining vapors, and a cooling means may be provided in the closed housing for expeditlng condensation. The cooling means may be a coil 25 mounted in the lower portion of housing i and adapted for circulation of a cooling liquid via an intake 26 and a discharge 21; and the cooling liquid may be circulated by a rotary pump 28 which may be mounted on motor 3 with an extension oi' the motor shaft 'forming the pump shaft. `The intake 29 to the rotary ,pump is connected to a source o supply for a cooling medium such as water, and the outlet 30 of the pump is connected by pipe 3i to the intake 26 of the cooling coil. A pipe- 82 is connected to the discharge 2i of the cooling coil, and may lead to a usual tower; and the cooling medium is preferably adapted for circulation radially 'outwardly through successive annuli of its cooling coil, so that the coldest condensate is at the center of housing l.

The condensate collecting in housing i may be withdrawn byoveriowing into a stand-pipe 35 which projects into the housing; and the motive iiuid for operating the pump may be a liquid :form oi the same fluid as that which the pump ls adapted to withdraw through the intake pipe 3, .so that the condensate collecting at the center of housing I below the level of the mouth of standpipev 35, andwhich is the condensate of lowest temperature, is the source of supply for the motive iluid which is drawn upwardly through bowl it when the pump is in operation, with the excess of said condensate overiiowing into the standpipe for ready recovery. i

The rotor of the pump is preferably driven at constant speed, with the pump regulated by controlling the supply of motive iiuid to the inducing jet; and for this purpose the intake at the lower end of bowl iii is provided with avalvular control. As an instance oi' 'this arrangement, a non-rotating sleeve 3B may project downwardly from the openI lower end oi' the bowl, with an ex-` ternal flange @l oi the sleeve in restricted vertically 'spaced relation above an internal` flange i3 of the bowl, so as to form a liquid seal between the rotating bowl and the non-rotating sleeve,

Vof the same type as that which is formed between harige il of stationary pipe 3 and the cooperating disc of the rotor. The sleeve it is preferably supported by a stationary annular baiiie 39 which surrounds bowl iii, with the annular baille suspended from a transverse partition plate t0 which is mounted in housing i below t the rotor and above the level of the fluid which .is contained in the housing. The plate 4i) may be suspended iron: radial fins Hi which project into housing i trom its peripheral wall, with the spaceabove and belowrthe transverse partition communicating at the circumferential spaces be-v tween the radial fins; and rotary agitation of the discharge from ports 22, which is collected and condensed in the lower portion of housing i, is thus arrested by the nns di, plate 40 and baille 39. Thermotive .duid which is drawn into bowl iii from the center of housing i, may be iiltered by an annular vertical filtering medium 42 extending irom plate i3 to the base of housing I and surrounding the inlet to the bowl; and the pressure in bowl iii and in housing i may be equalized through pipes 43 opening into the bowl below ange il, and communicating with that4 portion oi the housing i which is above plate f1 The vaivular control for the inlet to bowl Ill 45 :is mounted on sleeve 35; and may comprise a stationary disc i5 closing the inlet to the bowl and having an annular series of ports 46, with a cooperating disc il journaled on pipe 8 as shown at 43, and having an annular series oi' ports 49 adapted for variable alinement with ports 46 by rotatably adjusting the disc 4l with relation to the disc 35. The disc 41 may be rotatably adjusted by an operating connection projecting exteriorly of housing i, and shown as comprising a lug 50 depending from-disc 4l and adapted for engagement by a crank 5| of an operating rod @il which is iournaled in housing l as shown at 53, andwhich projects outside the housing where it is provided with an operating head 54.

The invention by providing a vacuum at intake pipel 8, and also providing for compressing and condensing the vapors which are drawn-on by the vacuum, is particularly applicable to either a solvent extracting plant or a mechanical reirigerating plant. For this purpose the intake pipe 8 may be connected to one side of the circulating system of such a plant by means of a coupling 5B, with the stand-pipe 35 connected to vthe opposite side of the circulating system by a coupling 5l. 'I'he housing i is nlled to the level of the mouth oir stand-pipe 35, with the solvent which is to be withdrawn and recovered from an extracting plant .or with the refrigerant which is to be evaporated and then compressed and 75 condensed for usual cycle of operation in a mechanical refrigerating system; and the solvent to be extracted, for example the solvent used in a dry cleaning plant, or the refrigerant for a refrigerating plant, may be trichlorethylene, in which case it is a body of this liquid which is contained in housing l. When the pump is in operation the coldest trichlorethylene from the center of' the housing I is drawn upwardly through bowl l by centrifugal force, and is impelled by centrifugal force and the blades l5 through the multi-stage jet of the rotor so as to create an appreciable vacuum at intake pipe 8. The trichlorethylene in which articles have been cleaned in a dry cleaning plant or the trichlorethylene employed as the refrigerant in a refrigerating plant, may thus be evaporated and drawn into pipe 8; and the trlchlorethylene vapors are to a large extent condensed in compression tube 2|, due to their compression in said tube and to the lower temperature of the cold trichlorethylene which is the impelling liquid and with which the entrained vapors are in intimate Contact, and condensation is then completed in housing I, so that the condensed trichlorethylene may be withdrawn through stand-pipe 35 and used over again in the plant.

I claim:

1. In combination, means for rotating a. mo-

'tive fluid for impelling the same b y centrifugal force, means for entralning a fluid medium by the impelled motive fluid, and means for regulating the supply of the motive fluid.

2. In combination, means for rotating a m0- tive fluid for impelling the same by centrifugal force, means for entralning a fluid medium by the impelled motive fluid, and means rotating with the fluid rotating means for delivering the entrained flow along a curvilinear path of travel.

3. In combination, means for rotating a motive fluid for impelling the same by centrifugal force, means for entralning a fluid medium by the impelled motive fluid, and means for delivering the entrained flow in a stream of reduced cross-sectional area.

4. In combination, means for rotating a motive fluid for centrifugally impelling the same, and means for entralning a fluid medium by the impelled motive fluid at successive points along the centrifugal path of travel of the motive fluid.

5. In combination, a multi-stage `iet for a motive fluid having its jet elements centrifugally one beyond another, means for rotating the jet for centrifugally impelling the motive fluid through the successive jet elements, and a combining tube cooperating with each element of the fluid medium by the impelled motive fluid, a stationary intake for said fluid medium, and a liquid seal between the rotor and the intake.

8. In combination, means for rotating a motive fluid for impelling the same by centrifugal force.

means for entralning a fluid medium by the impelled motive fluid, and means for confining and centrifugally delivering the entrained flow.

9. In combination, means for rotating a motive fluid for impelling the same by centrifugal force, 10 means for entralning a fluid medium by the impelled motive fluid, and means for confining and delivering the entrained flow along a path of travel extending radially outwardly and rearwardly curving with relation to the direction of l5 rotation.

10. In combination, means for rotating a motive fluid for impelling the same by centrifugal force, means for entralning a fluid medium by the impelled motive fluid, and means rotating with the fluid rotating means for confining and centrifugally delivering the entrained flow.

11. In combination, means for rotating a motive fluid for impelling the same by centrifugal force, means for entralning a fluid medium by 25.

the impelled motive fluid, and means for gradually restricting and delivering the entrained flow.

12. In combination, means for rotating a motive fluid for impelling the same by centrifugal force, means for entraining a fluid medium by the impelled motive fluid, and means gradually restricting and centrifugally delivering the entrained flow.

13. In combination, means for rotating a m0- tive fluid for impelling the same by centrifugal $5 force, means for entralning a fluid medium by the impelled motive fluid, and means rotating with the fluid rotating means for gradually restricting and centrifugally delivering the entrained flow.

14. In combination, means for rotating a moltive fluid for impelling the same by centrifugal force, means for entralning a fluid medium by the impelled motive fluid at successive points along the path of travel of the motive fluid, and means for confining-and centrifugally delivering the entrained flow.

15. In combination, means for rotating a motive fluid for impelling the same by centrifugal forcefmeans for entralning a fluid medium by the impelled motive uid at successive points along the path of travel of the motive fluid, and means for gradually restricting and delivering the entrained flow.

16. In combination, means for rotating a motive fluid for impelling the same by centrifugal force, means for entralning a fluid medium by the impelled motive fluid at successive points along the path of travel of the motive fluid, and

means for gradually restricting and centrifugally lll)A entralning a fluid medium by the impelled motive fluid at successive points along the path of travel of the motive fluid.

` DAN MCDONALD.

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