Molten Metal Transfer Pump

Abstract

(57) Molten metal transfer pump, in which a shaft (4) with the impeller (5) mounted on the shaft (4) is installed on the upper bearing (2) and the lower journal plain bearing (3). The lower journal plain bearing (3) has rotor (15) and stator (16) parts. The rotor part (15) is made in the form of two split bushings (17) mounted on the shaft (4), and the stator part (16) is made in the form of two split bushings (18) fixed in the cage (19) in axial alignment with the shaft (4). Bushings (17) (18) are fixed correspondingly with flat rings (24) (33) and composed of cylinder segments (20), (28) equidistantly placed in a circumferential direction, located correspondingly in the cylindrical groove (21) on the shaft and cylindrical groove (29) of the cage (19) and fixed with cone hold-down rings (22), (30) radially, and with spring rings (23), (31) axially.

Claims

1. The molten metal transfer pump comprises a case, in which a drive-connected shaft with the mounted impeller is installed on the upper bearing and lower journal plain bearing; the lower journal plain bearing comprises rotor and stator parts; the rotor part is made in the form of two bushings, mounted on the shaft, and the stator part is made in the form of two bushings fixed in the cage in axial alignment with the shaft; bushings of the rotor and stator parts have mating sliding surfaces and are made of silicon carbide based ceramics, the pump is characterized in that above the lower journal plain bearing in the opposite areas of the surface of the shaft and case multiple-thread oppositely directed helical grooves forming a labyrinth screw pump are milled; bushings of the rotor and stator parts are made in the form of split bushings fixed with flat rings and composed of cylinder segments equidistantly placed in a circumferential direction, located correspondingly in the cylindrical groove of the shaft and cylindrical groove of the cage and fixed with cone hold-down rings radially, and with spring rings axially, providing for axial pressing force.

2. The pump according to claim 1 is characterized in that the rotor part of the lower journal plain bearing is made with self-aligning segments, for which purpose each segment is resiliently pressed with a band spring located in the groove of the back surface of the segment and opposite groove of the shaft.

3. The pump according to claim 1 is characterized in that through radial slots are made in the flat ring of the stator part.

Description

BRIEF DESCRIBTION OF THE DRAWINGS

[0018] The present molten metal transfer pump is illustratively described in the drawing, where:

[0019] FIG. 1 shows a schematic general view of the molten metal transfer pump in longitudinal section;

[0020] FIG. 2 shows the lower journal plain bearing assembly in transverse section (assembly I, shown in FIG. 1);

[0021] FIG. 3 shows the transverse A-A section of the lower journal plain bearing assembly;

[0022] FIG. 4 shows an axonometric view of the stator part of the lower journal plain bearing;

[0023] FIG. 5 shows an axonometric view of the rotor part of the lower journal plain bearing assembled with the shaft.

DETAILED DESCRIPTION

[0024] The molten metal transfer pump (see FIG. 1) is intended for ensuring circulation of liquid metal coolant (for example, eutectic cerrobase) in the first circuit of nuclear reactor plant and comprises a case 1, in which the shaft 4 with axial-type impeller 5 mounted on the shaft 4 is placed on the water lubricant of the upper journal supporting bearing 2 and in the liquid metal coolant medium of the lower journal plain bearing 3; an axial-flow type impeller 5 is fixed on the shaft 4. In the case 1 above the impeller 5 an inlet guide vane 6 is located. Below the impeller 5 there is an outlet guide vane 7 with a baffle 8 meant for stabilization of liquid metal coolant flow coming out of the pump. Under the lower journal plain bearing 3 there is liquid metal coolant, formed by multiple-thread oppositely directed helical grooves, milled in the opposite areas of the surface of the shaft 4 and case 1. This liquid metal coolant flows through channel 10 to the labyrinth screw pump 9. Higher along the shaft 4 in case 1 the following components are located: thermal barriers 11, thermal protection unit 12, cooler 13 of the shaft 4 and magnetic liquid seal 14. The upper end of the shaft is connected to the drive, for example, by means of a coupling torsion sleeve (not shown in the drawing). The drive may be in the form, for example, of a gas-tight fire-safe electric motor. The lower journal plain bearing 3 has rotor part 15 (see FIG. 2) and stator part 16 (see FIG. 4). The rotor part 15 is made in the form of two split bushings 17 mounted on the shaft 4, and the stator part 16 is made in the form of two split bushings 18 fixed in the cage 19 in axial alignment with the shaft 4. Split bushings 17 of the rotor part 15 (see FIG. 5) are composed of cylinder segments 20 equidistantly placed in a circumferential direction (see 7 segments 20 in FIG. 3), located in the cylindrical groove 21 of the shaft 4 (see FIG. 2) and fixed with cone hold-down rings 22 radially, and with spring rings 23 axially, providing for axial pressing force. Between the split bushings 17 of the rotor part 15 there is a flat ring 24 meant for fixation of the bushings 17 with segments 20. Segments 20 of the rotor part 15 may be made in the form of self-aligning segments. In this embodiment each segment 20 can be resiliently pressed with a band spring 25 located in the groove 26 of the back surface of the segment 20 and in the opposite groove 27 of the shaft 4. Such design allows compensating the differences in thermal expansion of parts made of steel and ceramics. Split bushings 18 of the stator part 16 (see FIG. 4) are made in the form of split bushings and composed of cylinder segments 28 equidistantly placed in a circumferential direction (see 11 segments 28 in FIG. 3) located in the cylindrical groove 29 of the cage 19 and fixed with cone hold-down rings 30 radially, and with a spring ring 31 pressed with the upper bushing 32 axially. Between the split bushings 18 of the stator part 16 there is a flat ring 33 with through radial slots 34 meant for segments 28 fixation and providing for lubrication of segments 28 at the moment of pump startup. Segments 20, 28 of split bushings 17, 18 of the rotor and stator parts 15, 16 have mating sliding surfaces and are made of silicon carbide based ceramics.

[0025] The present molten metal transfer pump operates as follows. Prior to its filling with liquid metal coolant, the reactor monoblock unit is to be warmed. Then the first circuit of the reactor monoblock unit is filled with liquid metal coolant and drained. Chemically demineralized water with the temperature of 15-40° C. is supplied to the cooler 13 and the upper journal supporting bearing 2, after which the shaft 4 is switched on. By the action of the impeller 5 liquid metal coolant flows to the inlet guide vane 6 and then is fed by means of the impeller 5 to the outlet guide vane 7 with a baffle 8. At the same time liquid metal coolant coming through channel 10, is pumped with the labyrinth screw pump 9 to the end of the lower journal plain bearing 3, providing for reliable mode of liquid friction on the opposite surfaces of segments 20, 28 of split bushings 17, 18 of rotor and stator parts 15, 16 of the bearing 3 as well as for non-tearing operation of the bearing.