FR2616853A1 - SELF-PRIMING CENTRIFUGAL PUMP FOR DANGEROUS LIQUIDS ESPECIALLY RADIOACTIVE - Google Patents

Abstract

The present invention relates to a vertical self-priming centrifugal pump, placed under a protective slab, consisting of a fixed bowl welded to the suction and discharge pipes and of mobile equipment extractable from above, characterized in that the hydraulic part consists of a wheel 13 with radial fins driven by a drive shaft, that said wheel rotates between a lower plate 14 provided with a suction hole and an upper partition 20 hollowed out, on the wheel side, with an oval groove 23 terminated by a hole 21 allowing the liquid to exit.

Description

Self-priming centrifugal pump for dangerous liquids in particular

  radioactive. Transfers of dangerous liquids, in particular radioactive liquids, between two containers (tanks, devices, etc.), - one being a low container and the other a high container, by means of a pump, require special precautions namely: a) the pump must be placed above the low container, damage to the pump leading to a leak does not cause all the liquid to spill from the container, b) the discharge line must not immerse in the liquid from the high container, a pump stoppage or a leak should not siphon the contents of the high container,

  c) the pump must be removable without interrupting the canali-

  sation between the two receptacles, d) when the pump is used, more especially on radioactive liquids, provision may be made to place the two receptacles,

  the pump and the pipes in a "cell".

  It is advantageous to place the pump on the cell ceiling, with the vertical motor shaft passing through the ceiling slab, the electric motor of the pump being thus outside the cell.

easily accessible.

  A pump allowing these liquid transfers and having these various advantages has been described in the French patent.

no. 76 24748.

  The pump described in this patent externally comprises a bowl on which the suction and discharge pipes are welded and an internal hydraulic part which is disposed

  (with seal) in said bowl and which can be disassembled verti-

securely under protection.

  The present invention is a pump whose configuration is that described in said French patent but which offers a different internal hydraulic part in particular better suited to the transfer of liquids with low flow rates (by

example of the order of 2 m3 / h).

  The present invention therefore relates to a self-contained centrifugal pump.

  vertical priming, placed under a concrete slab, consisting

  a fixed bowl welded to suction and discharge pipes-

  ment and fixed under said slab and of an internal hydraulic part disposed in a sealed manner in said bowl and extractable from above, characterized in that said hydraulic part consists of a wheel (13) with radial fins driven by a driving motor shaft said slab, said wheel rotating between a plate

  lower (14) provided with a suction hole and an upper partition

  lower (20) forming the bottom of a chamber (12) and hollowed out, wheel side, an oval groove (23) going around said partition, said groove being closed at one of its ends and terminated by a hole (21) at the other of its ends, said hole allowing

evacuation of the liquid.

  The invention will be better understood and the other characteristics of the invention will emerge more easily by referring to the nonlimiting example below which illustrates the invention. The

  pump according to the invention is shown in Figures 1 to 7.

  Said figures represent: - Figure 1: a general vertical section diagramming the positions of the pump and its motor in a concrete slab; - Figure 2: a vertical section of the pump; - Figure 3: an exploded perspective view of the hydraulic part; - Figure 4: a perspective view of the lower closure of the hydraulic part; - Figure 5: a vertical section of the removable crew; - Figure 6: an enlarged vertical section of the hydraulic part;

- Figure 7: a joint model.

  General layout (Figure 1) A concrete slab 3, horizontal, separates a tall cell 1

  and a lower cell 2. Cell 2 containing dangerous products-

  reux is inaccessible to personnel while cell 1 is

  intended to stay clean and accessible.

  Pump 4 is placed in the low cell while the

  drive motor 7 is located in cell 1.

  The assembly of the motor comprises a Lantern 8, The motor shaft 6 and a bearing box 5. A coupling is placed between the motor and the shaft. General constitution of the pump The pump consists of an external bowl with tubing, a removable equipment, a rotating hydraulic equipment,

  ball bearings, fixed seals, rotating seals.

  The pump therefore consists of a bowl 15, of generally cylindrical shape, the upper part of which, open, forms a collar

  fixed to the concrete slab 3 and the lower part of which is closed.

  The bowl has three welded pipes (and welded to

  pipes): a suction pipe 18, a delivery pipe

  24 and a ventilation pipe (not shown). The tubing

  suction is welded to the pipe causing the fluid to be pumped.

  The delivery pipe is welded to the piping bringing

the pumped liquid.

  The ventilation pipe is connected to a general system of

ventilation.

  We must consider the bowl as fixed and constituting a whole

with piping.

  In the bowl takes place all the hydraulic part of the

  pump; this part is extractable and has a round crew

  nant and a mobile crew (the mobile adjective being there to remind

  that said moving assembly is extractable but, in the function-

  pump, said mobile assembly is of course fixed).

  The rotating assembly is shown, mounted in the bowl, in FIG. 2 and in exploded view for the winged wheel on the

figure 3.

  In FIGS. 2 and 3, one can see the rotating assembly which comprises: a driving shaft 6 guided in the upper part by the ball bearings 25, the seals (or rotating seals) 9, - at 13, at l 'lower end of the shaft, a fin wheel whose radially arranged fins are rectangular and regularly spaced. The arc of circumference between two consecutive fins is between 10 and 30 degrees and preferably around 15 degrees. Note that the impeller has

  a full central crown (34) (Figure 6) (not hollowed out in fins).

  In Figures 2, 3, 4, 5 and 6 we can also see the moving equipment which, with a few details, looks like

  a part of revolution around the axis of the motor shaft 6 (ver-

tical).

  The upper part of the movable assembly comprises flat parts which, being supported on corresponding flat parts of the bowl, make it possible to ensure sealing by means of two seals 30 and

32 (Figure 5).

  The lower part of the moving assembly forms a cylinder box.

  drique limited laterally by a wall 11, downwards by the

  removable base plate 14 (held in place by screws 33 -

  Figure 6) pierced with an orifice provided with the nozzle 16 and upwards by a plate 10 perforated with holes 29. The central part

  of this movable assembly surrounds the motor shaft 6, obviously leaving

  the necessary space for the seal (s) 9.

  Inside the cylindrical box is a horizontal partition-

  tale 20 which separates the interior of the box into two parts, a lower part which will contain the impeller 13 and a part

  high (12 Figure 7) forming the discharge chamber.

  Said partition 20 therefore delimits the lower chamber in which the impeller 13 is arranged; this partition and the rail it plays in the invention are described below with reference to

  more particularly in Figures 4 and 6.

  This partition has the shape of a thick circular disc hollowed out of a groove 23 on the underside. (It is recalled that Figure 4 shows the partition turned over to allow the groove to be seen).

  The groove ends with a hole 21 passing through the partition 20.

  A second hole 22 located on the same radius as the first hole 21,

  but closer to the center, also cross partition 20.

  At the top (see in particular Figures 2

  and 3), a small plate 17 separates the two holes 21 and 22.

  The groove 23 is surrounded by a flat part 35.

  Figure 6 shows that the groove 23 has the shape of a half

  oval and for example of a "basket handle". We also see in Figure 6 that the side wall 11 must, inside, have in the lower part, a concave profile

  31 extending the section of the groove 23.

  The relative dimensions (in diameter) of the groove 23 and of

  the impeller 13 are clearly indicated in FIG. 6:

  lette must occupy between 3/4 and 2/3 of the throat.

  By calling Ra the maximum radius of the impeller, Re the outside radius of the groove, Ri its inside radius, we should preferably have:

R - 1 (R -Ri)> R> R (R -Ri).

  e 4 e a eR 3-i By cons, the radius Rm of the hub 34 of the impeller 13 must be significantly smaller than the inner radius Ri of the groove. Figure 6 shows that there is a clearance between the impeller 13 and the partition 20 on the one hand and the base plate 14 on the other hand. This play must allow the free rotation of the wheel, but be weak enough for the capillary forces to ensure

  sealing of the two sides of the impeller.

  A play of 0.1 mm can be proposed as a preferred value.

  The correct functioning of the pump according to the invention

  implies, as the specialist imagines, that there is independent

  dance, that is to say preferably sealing, between the chamber

  suction 19 (Figures 2 and 7) between the bowl and the equi-

  mobile page and the discharge chamber 12 (FIG. 7).

  A joint can be placed between the wall 11 and the boss 39 of the bowl or, in a preferred manner, metal segments 38 are placed in grooves 36, 37 of the wall 11. The segments are preferably

2 in number.

  Note that it is imperative to leave a clearance between the throat bottom diameter and the inner diameter of the segment to

Allow the pump to be mounted.

26168-53

  We can tolerate a slight leak at the metal segments; its only drawback is to decrease (very little)

the pump flow.

  We will now briefly describe the operating mode-

  ment of the pump according to the invention which, as we recall, is a

self-priming centrifugal pump.

  We take as a starting point a stopped pump, containing

  enough liquid to immerse the wheel; there is air -

  in the suction pipe and in the upper part of the bowl.

  Upon rotation, the liquid present in the groove 23

  is pushed, through hole 21, into chamber 12.

  This volume of liquid is replaced by the same volume of air

from tubing 16.

  The rotation of the wheel mixes water and air and through hole 21 there comes out an unstable "emulsion". In zone 12 there is separation of the air which leaves through the holes 29 and the water which falls through the

hole 22 towards the wheel.

  The plate 17 separating the two holes prevents the emulsion

  fall back through hole 22 before the water-air separation.

  The same cycle is repeated until all the air from

  the suction line has been evacuated to the discharge.

  The liquid to be sucked then fills the pump which takes its normal hydraulic speed as a peripheral channel pump. We suck in the bottom of the bowl through the tubing 16, we push back through the hole 21

  in chamber 12 then through holes 29 in the discharge chamber

  12 'and the delivery pipe 24.

  We therefore put into operation a pump located above the liquid reservoir to be moved, without any valve which eliminates

the risk of leakage.

  For the dismantling of the pump, it should be noted that, by removing the motor, then the coupling, the entire interior of the pump can be extracted: mobile equipment and rotating part through the hole in the separation slab. The pump being placed above the tank and the pipes being welded to the remaining bowl

  in place, there is no spilled liquid.

6 16853

  It is necessary to protect personnel against the liquid remaining on the extracted part of the pump when the latter is radioactive. Finally, mention will be made of the dimensions and characteristics of one of the pumps that can be produced according to the invention: - impeller with a diameter of 90 mm; 10 mm thick and comprising 24 fins; - speed of rotation of the motor shaft 2 900 rpm; with said pump and by pumping cold water, the level of which is located 6.5 m below the pump, a flow rate of i 500 l / h is ensured if the water delivery level is at 46 m and from

  2,000 L / h if the delivery level is 25 m.

  This same impeller, used in a known centrifugal pump, would give a total head approximately 4 times more

low.

26 16853

Claims (5)

  1. Vertical self-priming centrifugal pump, placed under   a protective slab, consisting of a ballix welded to the pipes-   suction and discharge lines and mobile equipment extractable from above, characterized in that the hydraulic part consists of a wheel (13) with radial fins driven   by a drive shaft, that said wheel turns between a bottom plate   upper (14) provided with a suction hole and an upper partition (20) hollowed out, on the wheel side, with an oval groove (23) terminated by a   - 10 hole (21) allowing the liquid to exit.   2. Pump according to claim 1, characterized in that the upper closing partition (20) has a second hole (22) located practically on the same radius as the hole (21) but closer to the axis and than on the opposite face of the partition (20)   at the wheel (13) a plate (17) separates the holes (21) and (22). -   3. Pump according to claims 1 and 2, characterized in   that the groove (23) has a basket handle section and that the lower part (31) of the side wall (11) of the mobile equipment has a section continuously extending the section of the throat (23).   4. Pump according to claims 1 to 3, characterized in that   that the seal between the fixed bowl and the mobile equipment (11) is ensured by one or more metal segments each placed   in a groove (37) hollowed out in the side wall (11).   5. Pump according to any one of the preceding claims.   teeth, characterized in that the outer radius Ra of the impeller (13), the outer radius Re of the groove (23) and the inner radius Ri of said groove are linked by the inequality R -1 (R -Ri)> R> R - (R -Ri). e 4 e a e 3 e