US 2319730 A
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Description (OCR text may contain errors)
May 18, 1943- G. H. GARRAwAY 2,319,730
Filed Sept. 26, 1941 2 Sheets-Sheet l w C? :s q w Q IMay 18, 1943.
G. vH.. GARRAWAY PUMP Filed Sept. 26, 1941 2 .Sheets-Sheet 2 #6L/vaag?, BaMa/Zim# Patented May 18, 1943 PUMP George H. Garraway, North Plainfield, J., as-
signor to Standard Oil Development Company, a corporation of Delaware Application September 26, 1941, Serial No. 412,359
This invention relates to pumps and more particularly relates to centrifugal pumps adapted for pumping volatile fluids.
In centrifugal pumps, leakage from the stuffing boxes is a frequent source of trouble. Also, it is dangerous when light inflammable products are pumped due to the escape of such products through the stuiiing boxes. It is especially difficult to prevent leakage when pumping volatile liquids such as liquid propane and butane because of the high pressures encountered.
Centrifugal pumps have been made without stufiing boxes but Where they are used to pump volatile liquids they are made to operate in a Well l or a hole in the ground as they are quite long and must be set vertically. These pumps also require elaborate seals for the rotors.
A centrifugal pump made according to my invention has n-o stuffing boxes through which the fluid handled may leak. The pump is integrally built with a motor for driving the pump. It is compact and may be used in a horizontal or a vertical position. The pump impellers or pumping elements are supported from the inside of the rotor instead of from a rotatable shaft and the diffuser members are stationary and secured to a stationary central shaft. Radial bearing liners and thrust bearings are provided for the ends of the rotating unit. A plurality of impellers is used in combination with a plurality of diffuser members to provide a multiple stage pump whereby high pressures may be obtained while retaining the compactness of the device.
Hydraulic balance of the rotatable unit or rotor is maintained by balancing the flow of uid through the radial thrust bearing at the discharge end of the pump with the pressure at the suction end of the pump. Some of the fluid which escapes around the bearing at the discharge end of the pump is utilized to cool the laminations on the stator and rotor and also serves to cool and/or lubricate the bearing at the suction end.
In the dIaWiIlgS Figure 1 represents a longitudinal section with parts broken away to facilitate the disclosure;
Figure 2 represents a transverse vertical section taken substantially on line II-II of Figure 1; and
Figure 3 represents a detail of an impeller member with the cover broken away to show the vanes in the impeller member.
Referring now to the drawings, the reference character I generally designates the pump having an inlet or suction nozzle I2 and an outlet or discharge nozzle I4. The front end of the pump is formed by a dished front cover I6. A similar dished back or rear end cover I8 is provided. The front cover has a flanged central opening 2li. The inlet I2 comprises a sleeve 2| provided with a iiange 22 at its outer end to which ls attached the flanged opening 20of the front cover I6 by bolts 24. The front cover I6 also has a flanged outer periphery 26 which is secured to the annular stator shell 28 by means of bolts 3l.
The stator shell 28 has vertical sides 33 which extend inwardly and stator laminations 34 and windings 36 are held in thestator shell in the channel formed by sides 33. A stator sealing and insulating lining 38 is provided for the stator windings and laminations to protect them from the action of the iiuid being pumped. The lining 38 is very thin to keep the gap between the stator and rotor laminations at an eflicient minimum.
The back cover I8 has a flanged central opening 42 which is secured to flange 44 on outlet member I4 by bolts 46.
The inner end of the inlet member I2 is provided with a hub 54 provided with radial arms or Webs 56 to provide openings 58. 'I'he openings 58 are streamlined to reduce the resistance of the inlet to the incoming fluid. A stationary shaft 62 is provided for the pump and the shaft is arranged substantially centrally of the pump. At the inlet end, the shaft 62 has a reduced cy1indrical extension 64 which extends .through the opening 65 in hub 54. The outer or free end of the extension 64 is threaded to' receive a nut 66 which abuts the outer surface of hub 54 whereby the shaft is rigidly held in non-rotatable position.
l If desired, extension 64 may be anchored or secured to hub 54 as by a key.
The shaft 62 near lthe outlet member I4 is also provided with a reduced cylindrical extension 6l similar tol extension 64 which extends through opening 68 in the hub S9 of the outlet member I 4. The hub 69 is provided with radial arms or webs 'I2 to provide openings I4 for conducting the pumped fluid from the interior of the pump to Ithe outlet member I4. The stationary shaft 62 is secured to the hub 69 by means of a nut 'I8 threaded on the outer or free end of the extension 16.
The rotor or rotatable unit generally designated comprises a bearing bracket 82 having a sleeve 83 which surrounds the sleeve 2l on the inlet member I2. Bracket 82 has an upstanding outer end ange 84 adjacent the flange 22 on sleeve 2|. A bearing liner or bushing 86 is provided between the bracket sleeve 83 and sleeve 2| on the inlet member I2. The bearing liner 86 extends between the upstanding end ange 84 and the ange 22 on the inlet member I2 and acts as a thrust bearing.
Bracket 82 has an outwardly dished body portion 88 provided with a flanged periphery 92 to which is secured a flat annular extension 93 on an impeller or pumping element 94 by bolts 96. Secured to the extension 93 by bolts 98 is an annular member or sleeve |02 to which are secured the rotorlaminations |04 and rotor bars |06. From this it will be seen that impeller 94 is secured to the sleeve |02 around its entire periphery. Rotor lining |68 is provided between the annular member |02 and rotor laminations |04 to hold the laminatlons as a unit. The annular member |02 extends for the length of the pump and will be referred to hereinafter. 'I'he impeller 94 forms part of the rotor and from the above description it will be seen that impeller 94 is secured to and supported from the inside of the rotor which is a squirrel cage type, instead of from a shaft. All impellers are similarly supported.
The impeller 94 is a hollow annular member mounted within the pump for rotation therein. The impeller 94 has an inlet opening |I2 at its inner end adjacent the openings 58 in the inlet member I2 and an outlet opening II4 adjacent its periphery through which fluid is propelled by centrifugal force. The opening I2 is larger than the outlet opening ||4. The opening ||2 is about the same size as the openings 58 in hub 54 and tapers down to the smaller outlet opening 4. Impeller 94 is provided with curved vanes |I6 shown in Figure 3.
Impeller 94 has an annular extension I8 which forms one sideof openingl ||2 and which projects over and rotates on the inner end portionv of sleeve 2| of the inlet member I2 and acts as a seal, and another spaced annular portion |2| which forms the other side of opening ||2 and which projects over and rotates on the inner portion of sleeve 2| and one end portion of the stationary shaft .62. Impeller 94 is shown in vertical position and has its rear wall |22 substantially at and its front wall |23 inwardly tapered.- In Figure 3 front wall |23 has been removed to show the vanes |6.
Impeller 94 is associated with an annular hollow diffuser member |24 which is stationary and has a hub portion |25 mounted on and secured to shaft 62 by means of keys |26. Diffuser member |24 has a curved outer periphery |28 in the shape of a U-bend which cooperates with the outer end or opening I4 of impeller 94 to receive pumped fluid therefrom. The inner portion of the curved periphery of diffuser member |24 has an inlet opening I3I which is arranged close to the outlet ||4 of impeller 94 to receive pumped fluid therefrom. The U-bend on diffuser member |24 changes the direction of flow of the pumped uuid. Diffuserv member |24 is provided with vanes or diifusers |32 (see Figure ,2) which act to reinforce the diffuser member |24 and also to direct the pumped fluid inward toward the outlet |34 in the diffuser member |24. The outlet |34 in the diffuser member I| 24 is larger than the inlet l|3| to the diffuser member and is arranged adjacent the stationary shaft 62. The. one wall |35 of the diffuser member is substantially fiat whereas the other wall |36 is tapered from top to bottom to provide the large opening |34.
As the impeller 94 is rotated, fluid is drawn into the pump through inlet member I2 and the fiuid is thrown outwardly from the outlet ||4 of the impeller 94 by centrifugal force. The fluid is then discharged into the open end I3| of the U-bend portion of diffuser member |24 which reverses the ow of the pumped fluid and converts the velocity energy added to the fluid by impeller 94 into pressure energy. From the drawings it will be seen that the vanes in impeller 94 are curved opposite to the vanes hi the diffuser member|24. From the diffuser member outlet |34 near shaft 62 the pumped fluid is discharged to the next impeller presently to be described. By providing a plurality of sets of impellers and diffuser members, the pressure on the fluid may be increased or built up as the uid is passed through the pump.
The pump is provided with a plurality of spaced impellers and diffuser members. From the diffuser member |24 the iiuid is passed to the next impeller |42 which has a fiat extension |43 secured to the annular member |02 by means of bolts |44. Impeller`|42 has an inlet |46 adjacent the outlet |34 of diffuser member |24. Due to theconstruction of the pump, inlet opening ||2 on the first impeller 94 is different from the inlet |46 on the next impeller |42 in that inlet ||2 is provided substantially in the bottomyof the impeller 94 for cooperation with suction inlets 58 whereas impeller |42 has a lateral inlet opening |46 to cooperate with the outlet |34 of diffuser member |24. The intermediate impellers are of substantially the same construction.
The inlet |46 on impeller |42 is of substantially s the same size as the outlet |34 in the diffuser member |24. A close clearance is maintained between inlet |46 and outlet |34 to reduce recirculation of pumped fiuid to a minimum. Recirculation cools inside of rotor laminations. Impeller |42 has an outlet I 48 in its periphery adjacent the inlet opening of the next diffuser member |52 which is similar in construction to the diffuser member |24 hereinbefore described. Outlet |48 in the periphery of the impeller |42 is smaller than the inlet |46 in the impeller |42.
Diffuser member |52 has a curved outer periphery or U-bend |54 and an inlet |56 adjacent the outlet |48 in the impeller 42. Diffuser member |52 has a hub portion |51 which is secured to the stationary shaft 62/by keys |58 and is therefore held in a stationary position during the operation of the pump.
Diffuser members and impellers are alternated for the length of the pump and the desired number of sets installed to provide a pump which pumps fluid and places it under pressure as it passes through the pump from impeller to diffuser member. 'Ihe pumped uid under pressure passes through the last impeller |62 and last diffuser member |64 and then through outlet member I 4. The diffuser members are all of substantially the same construction except the last diuser member |64 which has a bottom outlet |65 to cooperate with the discharge openings 'I4 in discharge nozzle I4. Outlet I 65 is of substantially the same size as the discharge openings 14. Diffuser member |64 has a curved outlet |65 having an annular portion |65' which is supported on a portion of the discharge nozzle I4. The remaining diffuser members are of substantially the same construction. The last diffuser member |64 has a hub |66 which is keyed to the stationary shaft 62 by keys |61. The last impeller member |62 is secured to the annular member |02 vious impellers.
Bracket |68 on rotor 80 at the outlet end of the pump is similar to the bracket 82 hereinbefore described which is arranged near the inlet end of the pump. Bracket |68 has a :flanged outer end |12 adjacent flange 44 on the outlet member I4. A bearing liner or member |13 is positioned between sleeve |14 on bracket |60 and sleeve |15 on outlet member |4. A portion of the bearing member extends between the flange |12 on bracket |68 and the flange 44 on the outer end of the outlet member I4 and acts as a thrust bearmg.
Annular member I02 which forms part of the rotor or rotating element of unit 80 includes sections which are bolted together to make a large sleeve or annular member |02 and thev laminations |04, rotor bars I 06 and short circuiting rings |16 of the rotor are attached to the outer periphery of the annular member |02. From the above description it will be seen that the entire pump is formed of sections bolted together or otherwise secured together so that the entire pump may be readily assembled and disassembled and all the impellers and diffuser members removed or replaced. The annular member |02 is secured to the impeller members by means of ilat extension members as hereinbefore described. The laminations and rotor bars on the exterior of the annular member |02 and rotor 80 are arranged in close spaced relation to the laminations and windings on the stator 28. The arrangement of stator windings and rotor laminations forms an induction motor of the squirrel cage type for rotating the impellers. v
The pump inner casing together with the impellers and motor rotor forms a single rotating unit supported by radial bearings at both ends and with thrust bearings being provided for both ends. The bearings 8B and |13 rotate with the rotor as a unit.
The discharge end bearing |13 acts as a bearing liner and also as a rotating pressure breakdown device. The pressure at the discharge end of the pump near outlet |4 is of course at a higher pressure than the inlet end and some of the uid under pressure escapes around bearing |13. To equalize the pressures at the ends of the pump a bleed line may be provided. The outlet end cover I8 is provided with an opening |18 for receiving a bleed 'line (not shown) for connection with the interior of the inlet member I2. The bleed line may be connected with the suction line or the vessel from which the pump takes suction. The bleed line acts to equalize the pressures at the discharge end and inlet end of the pump and axial balance is maintained in this Way.
Some of the fluid which escapes around the radial bearing |13 does not return to the suction end I 2 through the bleed line but passes through the clearance between flange |12 and flange 44 at the discharge end of the pump and goes up and around to the squirrel cage rotor, passing between and serving to cool the laminations on both the stator and the rotor. It then passes through suction end bearing (thus cooling and lubricating it) and returns to suction of rst stage.
The operation of the device will now be described. A volatile liquid such as propane or butane under superatmospheric pressure is led from a source of supply to the inlet member I2. Electricity is supplied to the induction motor to cause rotation of the rotor 80 comprising the impellers 94, |42, |62, etc. Brackets 82 and |68 and sleeves 83 and |14 rotate with the impeller members as a unit. As the impellers rotate, they draw in liquid propane through their inlets and throw it outwardly by centrifugal force through their outlets. In this way velocity energy is added to the liquid propane and it is thrown outwardly from the outer periphery of the impeller into the diffuser member. In the diffuser member the velocity energy is converted to pressure energy and the propane is placed under greater pressure. From the diiuser member '|24 the liquid propane is passed to the next impeller |42 Where the liquid propane is again thrown out by centrifugal force and Velocity energy is added to the liquid propane. From here the liquid propane is passed to the next diffuser member |52 where the liquid propane is placed under a greater pressure.
The liquid propane is passed through the pump in this manner passing from each impeller to the next diffuser member until it reaches the last diffuser member |64 at which time the liquid propane is under the desired pressure. From here the liquid propane under pressure passes through outlet member I4 to a suitable tank or other distributing point.
From the above disclosure it will be seen that I have provided a centrifugal pump which has no stuiling boxes and in which leakage losses are avoided. The pump is relatively simple and of compact construction due to the inclusion of the pumping element inside of the motor rotor. The rotating impellers are supported from the outside periphery of the pump rather than on the central shaft. The size of the shaft can be greatly reduced in diameter because the only load on the shaft is the static load of the diffuser members rather than the dynamic load of impellers and associated parts as used in ordinary centrifugal pumps. The pump is in hydraulic balance and as a result thrust loads will be very small.
While I have shown a preferred form of my pump, it is to be understood that this showing is by way of illustration only and various changes and modications may be made without departing from the spirit of my invention.
1. A centrifugal pump without stuffing boxes including a stator shell and a rotor each provided with laminations to form an electric motor, relatively short stationary inlet and outlet members, said inlet and outlet members each having a hub at their inner ends, dished front and back cover members for xedly connecting said inlet and outlet members to said stator. a stationary shaft extending longitudinally of the pump along its axis, means for securing one end of said shaft to said hub in said inlet member and the other end of said shaft to said hub in said outlet member, said rotor including a relatively large cylinder concentric with said shaft and having dished bearing brackets provided with sleeves rotatably mounted on said inlet and outlet; members, bearing means between said sleeves and said inlet and outlet members, said rotor also including open ended hollow and annular impeller members having circumferential extensions connected to said cylinder and being concentric with said shaft, each impeller member having an inlet adjacent said shaft and an outlet adjacent said cylinder, a plurality of open ended, stationary hollow annular diffuser members I'lxedly held on and concentric with said stationary shaft, each diffuser member having an inlet near the outlet of one impeller member and an outlet adjacent said shaft and near the inlet of the next impeller member, whereby rotation of said rotor causes uid to pass through said inlet member, then an impeller member, then a diiuser member and successive impeller and diffuser members until the fluid is discharged through said outlet member at a higher pressure than it was at the inlet member.
2. A pump according to claim 1 wherein each of said inlet and outlet members has an outer flange and each of said dished bearing brackets has an end ange adjacent each of said flanges I on said inlet and outlet members and bearing liners between each outer flange and end ange to act as thrust bearings.
' GEORGE H. GARRAWAY.