Mainline electric oil pump assembly and method for assembling same

Abstract

The mainline electric oil pump assembly relates to the field of assemblies for pumping oil in main oil pipelines. The aim of the present invention is to create a mainline electric oil pump assembly with improved technical and economic characteristics, reduced noise and vibrations, and increased reliability, service life and performance. The main distinguishing features of the proposed assembly which contribute to the achievement of the aforementioned aim are: the non-splined, zero-backlash seating of the impeller on a smooth shaft, the use of roller bearings seated in a non-splined, zero-backlash fashion on the smooth shaft, the use of mechanical seals seated in a non-splined, zero-backlash fashion on the smooth shaft, the use of self-correcting adjustable spherical supports under the supporting feet of the pump, and the boring of the seating surfaces of the pump housing for the rotor in a single set-up operation.

Claims

1. An electric pump assembly comprising a horizontal single-stage double-volute pump, an electric drive motor, a coupling connecting the pump and the motor, and a common or separated frames for mounting the pump and motor thereon, the pump comprising: a housing and a cover with two semi-volute inlets and a double-volute outlet, a rotor consisting of a shaft and an impeller being installed between the housing and the cover, the impeller being seated on the shaft by way of a double-sided collet clamping device having taper sleeves and screws, rotor mechanical seals being seated on the shaft by way of single-sided collet clamping devices having taper sleeves and screws, the double-sided and single-sided collet clamping devices being a combination of coaxial rings with tapered working surfaces with the coaxial rings being slidable by using one or more clamping screws along an axis of the shaft relative to each other to clamp the coaxial rings to the shaft, the rotor being mounted relative to the housing using roller bearings of two types: a double-row spherical roller bearing taking up axial load of the pump shaft, and a floating toroidal roller bearing, wherein the double-row spherical roller bearing and the floating toroidal roller bearing are mounted on the shaft using a pair of tapered adapter sleeves.

2. A pump assembly of claim 1, wherein mounting surfaces for pump feet of the pump are set to the level of a common central axis of a suction nozzle and a discharge nozzle of the pump.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a general view of electric pump assembly;

(2) FIG. 2 is a view of a pump with connected pipelines;

(3) FIG. 3 is a perspective view of upgraded mainline oil pump;

(4) FIG. 4 is a general side cross-sectional view of a pump;

(5) FIG. 5 is a gap-free double-sided clamping device for mounting impeller to a shaft;

(6) FIG. 6 is a gap-free single-sided clamping device of one of the two mechanical seals of the shaft;

(7) FIG. 7 is a bearing support (assembly) of the pump rotor with a toroidal roller bearing;

(8) FIG. 8 is a bearing support (assembly) of the pump rotor with a double-row spherical roller bearing;

(9) FIG. 9 is a mounting support under the pump foot and electric drive motor in a scaled-up side sectional view;

(10) FIG. 10 is a general longitudinal cross-section of compensating dual disc coupling between the pump shafts and the electric drive motor;

(11) FIG. 11 is a scheme of modified semi-volute pump inlet.

DESCRIPTION OF EMBODIMENT

(12) In the figures in total numbering of the positions are marked the following significant components and parts in large scale. The most significant components and parts of electric pump assembly are: a horizontal single-stage double-volute pump 1, an electric drive motor 2, a frame 3, mounting supports 4 under the feet 5 of a pump and a motor, and a coupling 6. The most significant components and parts of a pump: a cast housing 7 with two semi-volute inlets and a double-volute outlet and a cast cover 8 of the pump housing (with a common horizontal plane of the parting on the common central plane of symmetry of the holes for the pump rotor), a pump rotor consisting of balanced and machined shaft 9 and impeller 10, a double-sided collet clamping device 11 of the impeller on the shaft, two shaped sleeves 12 on the shaft to form the flow part of the pump, mechanical seals 13, single-sided collet clamping devices 14 on the shaft, two different roller bearings: double-row spherical roller bearing 15 and toroidal roller bearing 16, taper fastening sleeves 17, 18 for bearings 19, 20, tube-type bearing housings (console supports), bearing lubrication and sealing system, sets of fasteners (screws, bolts, nuts, pins, removable taper pins with threaded ends).

(13) To ensure a firm zero-backlash connection of the impeller and a shaft, a clamping element consisting of three major parts: a central ring into which identical side rings are drawn by the force of screw tightening, wherein the taper surfaces of the rings are pressed against the tapered surfaces of the ring, is used. The central ring and the side rings come into contact by taper surfaces. The connection is self-centering relative to the axis of rotation and is being an easily mounted pressure connection. The connection transmits considerable torque and axial forces.

(14) To secure the connection of the bearing housings, a taper ratio of removable taper pins is small, usually 1:50. To remove the pin its threaded end is used.

(15) Taper clamping sleeves of bearings are equipped with axial section to increase the flexibility of the sleeve body.

(16) The frame of the assembly is preferably manufactured of channels, under the engineering empirical recommendations the channel size is approximately 0.1 of the maximum overall size of the frame.

(17) Factors affecting the characteristics of a conventional assembly, primarily parameters of its vibration and noise are the following: mechanical: rotor imbalance; shaft length of the rotor, its profile with key grooves and keyed connection with gaps; bearing supports; pump shaft and drive motor misalignment; the degree of non-rigid fixing of the assembly to the frame; hydrodynamic: blade vibration and off-design (unrated) operation of the pump.

(18) The main technical design solutions that improve the performance of the referred characteristics of the pump assembly reducing in the first place vibration and noise of the pump assembly are: the use of non-splined zero-backlash seating of the impeller on a smooth shaft, the use of tailored roller bearings seated in a non-splined and zero-backlash fashion on a smooth shaft, the use of mechanical seals seated in a non-splined and zero-backlash fashion on a smooth shaft; the use of self-correcting height-adjustable spherical mounting supports under the feet of the pump and motor;

(19) and the main technological solution: in the process of assembling the pump: boring of the seating surfaces of the pump housing for the rotor in a single set-up operation.

(20) The main advantage of using collet clamping devices with taper sleeves and screws is a complete replacement of splined connections, and thus removing the source of dangerous stress concentrators of rotor shaft that is guaranteed to have impact on reducing the vibration activity and increasing the resource of the pump rotor and the pump assembly as a whole. Collet clamping device has no backlash, does not damage the surface of the shaft and the hub, easily installed and removed of the clamping connection.

(21) The main advantage of the use of tailored roller bearings, allowing floating the rotor shaft without bending (toroidal roller bearing) and easily perceiving changes of the length of the shaft caused by thermal displacements (double-row spherical roller bearing) is the possibility of significant shortening (15-20%) of the length of the shaft with bearings with increasing rigidity and a corresponding decrease in its vibration activity. In addition, the tubular bearing housings instead of demountable semi-tubular bearing housings also improve the stiffness characteristics of the pump.

Detailed Assembling of the Pump

(22) Before assembling the pump, perform boring of holes with a boring bar on a boring machine in the housings in a single set-up operation (when boring of the said holes the empty hearing housings must be secured on the pump housing by screws and fixed by the pairs of removable taper pins).

(23) Next, connect the rotor shaft and impeller by double-sided collet clamping connection with taper sleeves and screws. Secure position of the impeller relative to the shaft through a tool in the form of a tube with precise measuring length with disc and screw holes at the end. When installing the impeller, put the tube on the shaft all the way until the disc stops at the end of the shaft and through the hole in the disc attach it to the end of the shaft by screw. Tighten the screws of the collet connection in three bypass tightening torque 0.3T, 0.7T and T.

(24) Set dummy screws to connect the impeller with a shaped sleeve on the side opposite main screws of collet connection.

(25) Set the shaped sleeves on both sides of the impeller, secure them with nuts and lock nuts.

(26) Lower the shaft with pre-installed rings (centering rings) into the pump housing and install the rings in the grooves of the housing.

(27) By displacing the shaft along the axis achieve gap equality between the impeller and the rings, insert temporary spacers (gauges) into these gaps for axial fixation of the shaft relative to the pump housing.

(28) Separately, on mounting table assemble two bearing assemblies. When assembling the bearing assembly with a double-row spherical roller bearing insert the bearing into the bearing housing and fix it by dummy cap. Similarly, assemble another bearing assembly with a toroidal roller bearing.

(29) On both sides of rotor shaft install machine seals, brass seal sleeves (they may be sealed with a screw) and compensating rings (not shown in the figures).

(30) Install the bearing assembly on the shaft, insert a taper sleeve into the bearing (from the bearing kit) and secure with a nut. Install the screws to connect the bearing housing to the pump housing. Screwing up the said screws by hand and using the mounting gaskets ensure that mating planes of bearing housing and the pump are parallel. Measure with a gauge the clearance between the mating plane of the hearing housings and the pump housing. Having dismantled the bearing assembly, remove the ring and reduce its thickness by the amount of clearance that will allow in final assembling to provide a corrected clearance between the mating planes of the bearing housings and the pump housing close to zero.

(31) Remove temporary spacers from the axial (side) gaps.

(32) Install the pump cover to the pump housing. To do this, having lubricated the contacting surfaces with a liquid gasket (anaerobic sealant-monomer), gently lower the cover of the pump onto the pump housing, install the pins and secure it to the housing, turning the nuts in a few rounds. Make sure that when the lid is lowered projections of the rings were in response grooves of the pump cover. Leave the construction alone for a time sufficient to polymerize the sealant.

(33) Assemble mechanical seals, having installed them so that one of the openings for washing of the mechanical seal was drawn towards the upper opening in the pump cover. Secure the mechanical seal on the pump housing by pins and on the shaft in the axial direction by a single-sided collet clamping device. Disassemble spring clips of mechanical seals.

(34) Install the bearing assembly on the shaft, having pre-set a ring, a sleeve and a compensating ring (not shown). Install between the bearing and the shaft a taper clamping sleeve, tighten the nut by standardized torque and lock it. Tighten the screws by hand and, using the mounting screw, align the pin holes in the bearing housing with the mating holes in the pump housing. Install tapered pins, tighten and lock the screws.

(35) Remove the dummy cover and install the cover in its place. By adjusting gasket thickness ensure the absence of the axial bearing clearance relative to its body.

(36) When installing the support with toroidal roller bearing fit of the flanges of the bearing housing and the pump will be provided by the axial mobility of the roller bearing rings. However, to optimize the conditions of its operation, it is necessary to mate the end face planes of inner and outer rings, which is ensured by adjusting thickness of a compensating ring (not shown). To do this, install and secure the bearing assembly on the pump housing by tightening the screws by hand, set a tapered clamping sleeve into the bearing and tighten the nut. Measure the relative displacement of the outer and inner bearing rings and adjust the thickness of compensating ring against the displacement. Then finally install and secure the bearing assembly.

(37) Check freedom of rotation of the assembled pump.

(38) The assembling of the pump is over. If necessary, bearings and mechanical seals of the rotor shaft may be replaced without disconnecting the cover and the pump housing.

(39) Further is a description of the assembling process of the pump assembly in the following sequence of techniques: mounting of a common frame or individual frames to a foundation, horizontal levelling of their support surfaces at two levels, and finally mounting the frames to the foundation, fitting mounting of the pump and/or electric motor to the frame or individual frames on mounting supports; producing general through holes in the supports, feet and the corresponding mounting surfaces of the frame and presetting of mounting bolts in produced through holes, welded or flanged connection of pump nozzles with pipelines; adjustment and final installation of all mounting supports under the pump and the electric motor, simultaneously using laser for precise alignment of the pump and electric motor shafts; final tightening of the mounting bolts of supports; connection of the pump and electric motor shafts exhibited coaxially aligned and spaced apart from each other by installing a compensating dual disc coupling with the intermediate shaft.

(40) The assembling of the pump assembly is over. If necessary, the sleeve between the shafts can be removed without moving the pump or electric motor.

(41) An example of assessing the benefits of a method for assembling the pump assembly.

(42) Preliminary tests of the pump assembly prototypes and expert evaluation showed the following relative values of impact of the proposed technical solutions, primarily to reduce the vibration of the pump assembly, shown in the table on a separate sheet.

(43) Thus, as a result of all proposed inventive improvements of the pump assembly (its vibration activity and noise are reduced, and resource is increased), its performance will be substantially improved, and hence the main aim of the present invention achieved.

(44) TABLE-US-00001 Table of technical solutions to reduce vibration of electric pump assemblies having pumps of type NM 1250 . . . 10000 Technical solution reducing vibration Non-splined, Use of roller Use of mechanical Use of self-correcting Boring of the seating zero-backlash beaings seated in a seals seated in a adjustable spherical surfaces of the pump seating of the non-splined, zero- non-splined, zero- supports under the housing for the Factors influencing impeller on a backlash fashion on backlash fashion on supporting feet rotor in a single vibration parameters smooth shaft the smooth shaft the smooth shaft of the pump set-up operation Mecanical Rotor imbalance Speed n and 2 n * Speed n and 2 n * Speed n, 2 n Speed n and 2 n * Speed n and 2 n * Reduced by 15-20% Reduced by 20-25% Reduced by 3% Reduced by 25-50% Reduced by 20-25% Shaft length and Speed n and 2 n * Speed n and 2 n * Speed n and 2 n Speed n and 2 n * its profile Reduced by 5-10% Reduced by 20-25% Reduced by 1-3% Reduced by 5% Sliding bearing Speed 0.5 n and n * Speed 0.5 n and n * Speed 0.5 n and n* supports Reduced by 10-15% Reduced by 20-25% Reduced by 1-3% Misalignment of Speed n and 2 n * Speed n and 2 n * Speed n and 2 n * Speed n and 2 n * pump and drive Reduced by 5-10% Reduced by 10% Reduced by 25-50% Reduced by 10% motor shafts Mounting rigidity Speed 0.5 n and n * Speed 0.5 n and n * Speed n and 2 n * Speed n and 2 n * of the assembly Reduced by 3-5% Reduced by 5-10% Reduced by 25-50% Reduced by 5% to a frame Hydrodynamic Blade vibration Speed k*n; 2*k*n; Speed k*n; 2*k*n; Speed k*n; 2*k*n; Speed k*n; 2*k*n; 4*k*n 4*k*n 4*k*n 4*k*n Reduced by 10% Reduced by 10% Reduced by 5% Reduced by 5% Operation of the Speed k*n; 2*k*n; Speed k*n; 2*k*n Speed k*n; 2*k*n; Speed k*n; 2*k*n; Speed k*n; 2*k*n; pump in non- 4*k*n 4*k*n 4*k*n 4*k*n 4*k*n design mode Reduced by 5% Reduced by 5% Reduced by 3% Reduced by 10-20% Reduced by 5% Symbols: nrotor speed, Hz (usually 50 Hz = 3000 rev/min) knumber of impeller blades (in proposed pump k = 7) factor 2of availability of keys in conventional versions of mainline oil pump factor 0.5of availability of bearings in conventional versions of mainline oil pump