KR960016790B1 - Centrifugal pump for handling danger liquid particularly adapted for automatic full liquid priming of radioactive liquid - Google Patents

Abstract

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Description

Self-priming centrifugal pumps for hazardous liquids, especially radioactive liquids

1 is a cross-sectional view schematically showing the position of a motor and a pump in a concrete slab.

2 is a cross-sectional view of the pump.

3 is an exploded perspective view of the hydraulic unit.

4 is a perspective view of a lower closure part of the hydraulic part.

5 is a cross-sectional view of a decomposable device.

6 is an enlarged cross-sectional view of the hydraulic unit.

7 is a seal design diagram.

* Explanation of symbols for main parts of the drawings

1,2: compartment 4: pump

7: drive motor 13: wheel

15: bowl 21, 22, 29: hole

31: recess 38: metal piece

The present invention relates to a self-priming centrifugal pump for dangerous liquids, in particular radioactive liquids.

Special care must be taken when transferring hazardous liquids, especially radioactive liquids, between the lower and upper vessels (tanks, devices, etc.) by means of a pump. That is: a) the pump should be placed on top of the lower container and all liquids in the container should not spill even if the pump causing the leak is sent. b) The discharge pipe shall not be submerged in the liquid of the upper container, and the stoppage or leakage of the pump shall not suck up the contents of the upper container. c) The pump must be detachable without blocking the pipe between the two containers. d) When pumps are used, especially when used for radioactive liquids, they should be configured to place two vessels, pumps and tubes in a "compartment".

It is advantageous to position the pump at the ceiling of the compartment with a vertical drive shaft passing through the ceiling slab, whereby the motor of the pump is external to the compartment and easily accessible.

A pump which enables this liquid transfer and offers several advantages is disclosed in French Patent No. 76 24748.

The pump disclosed in this patent has a bowl to which the suction and discharge pipes are welded, and an internal hydraulic part which is disposed in the bowl and is vertically separable for protection.

The present invention provides a pump similar to that disclosed in the French patent, but which presents a different hydraulic part which is more suitable for low flow (e.g. on the order of 2 m ³ / hr) liquid transfer.

Accordingly, the present invention is composed of a bowl fixed to the bottom of the slab and welded to the suction and discharge pipe, and an internal hydraulic part arranged to be extrudably disposed in the bowl and to be pulled out through the upper part and under the concrete slab. A vertical self-priming centrifugal pump positioned; The hydraulic part is constituted by a wheel (13) having radial vanes driven by a drive motor traversing the slab; The wheel rotates between a lower plate (14) having a suction hole and an upper partition (20) formed with an elliptical groove (23) formed at a side adjacent to the wheel and forming a bottom of the chamber; The groove provides a self-priming centrifugal pump passing through the partition wall and closed at one end and terminated by a hole 21 for discharging liquid at the other end.

Next, the present invention will be described in more detail with reference to the accompanying drawings.

In the figure, firstly, FIG. 1 shows a general arrangement, in which the horizontal concrete slab 3 separates the upper compartment 1 and the lower compartment 2. Compartments (2) containing dangerous goods are difficult for people to access, while compartments (1) are clean and accessible.

The pump 4 is located in the lower compartment 2, while the drive motor 7 is located in the upper compartment 1.

The motor assembly comprises a cage element 8, a drive shaft 6 and a ball bearing housing 5. The coupling is located between the motor and the shaft.

A typical pump consists of an outer bowl with a conduit, a detachable device, a rotary hydraulic device, a ball bearing, a fixed seal and a rotary seal.

The pump thus consists of a generally cylindrical bowl 15 with an open top forming a flange fixed to the concrete slab 3 and a closed bottom.

The bowl includes three welded conduits (and welded to the tubes): suction conduit 18, delivery conduit 24 and ventilation conduits (not shown), the suction conduits are welded to the tube leading the fluid to be pumped. .

The delivery conduit is welded to the pipe leading the pumped liquid.

Ventilation conduits are connected to the general ventilation system.

The bowl shall be judged as fixed and integral with the tubes.

The bowl is positioned with all hydraulic parts of the pump: this hydraulic part is designed to be pulled out and includes a rotating device and a moving device. (The moving device can be pulled out, but an additional moving part may be used to fix the pump. ).

The rotating device is mounted to the bowl as shown in FIG. 2, and the vane wheel is shown in exploded view in FIG.

2 and 3 show a rotating device comprising:

A drive shaft 6 guided from the top by a ball bearing 25. Packing (or rotary seal 9), vane-shaped wheel 13 with vanes arranged squarely at the bottom of the shaft and spaced at regular intervals, the arc between two neighboring vanes being 10 ° and 30 Preferably it is between ° and close to 15 ° The vane wheel includes a solid center ring 34 (without vanes) (206 degrees).

2, 3, 4, 5 and 6 also show the movable device, which is in the form of rotating about the axis of the (vertical) drive shaft 6.

The upper portion of the movable device includes flat portions adjacent the corresponding flat portions of the bowl and which ensure tightness thanks to the two seals 30, 32 (see FIG. 5).

The lower part of the mover forms a cylindrical box, which is in place by means of a removable foundation plate 14 (Fig. 6-screw 33) which penetrates into an orifice with a wall 11, a nozzle 16. Fixed), and the plate 10 in which the holes 29 are formed, the sides, the lower part and the upper part are restricted.

The central part of the actuator encloses the drive shaft 6, leaving the necessary space for each packing 9. Inside the cylindrical box there is a horizontal bulkhead 20, which is the lower part that will contain two parts, the vane wheel 13, inside the box and an upper part 12 forming a delivery chamber (FIG. 7). Divide by.

Accordingly, the partition wall 20 forms a lower chamber in which the vane wheel 13 is disposed. Such a partition and the role of such a partition in the present invention will be described next with reference to FIGS. 4 and 6.

This partition is a thick disc with a groove 23 formed on its lower surface (FIG. 4 shows the partition inverted to show such a groove).

The groove ends in a hole 21 across the partition wall 20. The second hole 22, which is closer to the center and on the same radius as the first hole 21, also crosses the partition 20.

At the top (for example in particular the second and third views), the small plate 17 separates the two holes 21, 22.

The groove 23 is surrounded by the flat portion 35.

6 shows that the groove 23 is in the form of a semi-ellipse, for example a "basket handle."

Similarly, FIG. 6 shows that the side wall 11 provides a recess 31 which extends into the groove 23 portion in the lower part of the inside.

The relative dimensions (in diameter) of the groove 23 and the vane wheel 13 are clearly shown in FIG. The vanes should occupy between 3/4 and 2/3 of the groove.

When the maximum radius Ra of the vane wheel, the outer radius Re of the groove, and the inner radius Ri are the following formulas are preferable.

In contrast, the radius Rm of the hub 34 of the vane wheel 13 is significantly smaller than the inner radius Ri of the groove.

6 shows a gap formed between the bay wheel 13 and the partition wall 20 on the one hand and the vane wheel 13 and the base plate 14 on the other hand. This gap should allow the free rotation of the wheel, but should be small enough that the capillary force enables the tightness of the two sides of the vane wheel.

The gap is preferably 0.1 mm.

As will be readily appreciated by the expert, the improved operation of the pump according to the present invention comprises the suction chamber 19 (second and seventh) and the discharge chamber 12 (seventh) contained between the bowl and the actuator. Independence, preferably withstand resistance between the figures).

The seal may be located between the boss 39 of the bowl and the wall 11, or the metal piece 38 may be preferably located in the grooves 36, 37 in the wall 11. It is preferable that two metal pieces exist.

In order to be able to assemble the pump, a gap is necessarily required between the inner diameter of the metal piece and the diameter of the groove bottom.

A slight leak can withstand the level of metal pieces. The only drawback here is that the flow rate of the pump is reduced but only slightly.

Next, the operation mode of the pump according to the present invention, which is a self-priming centrifugal pump, will be briefly described.

The starting point is a stationary pump that contains enough liquid to submerge the wheel. There is air in the upper part of the bowl and in the suction line.

In rotation, the liquid in the grooves 23 is transferred to the chamber 12 through the holes 21. This amount of liquid is replaced by the same amount of air exiting conduit 16.

The rotation of the wheel mixes water and air, and an unstable "emulsion" exits through the hole 21. In zone 12 it is separated into water falling into the wheel via a hole 22 of air exiting through the hole 29.

The plate 17 separating the two holes prevents the emulsion from falling through the holes 22 before being separated into water and air.

The same cycle is repeated until all the air in the suction line is discharged and exhausted. The sucked liquid is then filled in a conventional hydraulic pump, such as a peripheral channel pump. Suction occurs at the bottom of the bowl via conduit 16, and delivery occurs via hole 21 in chamber 12 and hole 29 and delivery conduit 24 in delivery chamber 12 '. .

Thus, the pump is located above the container of the liquid to be removed without requiring another valve, thus eliminating the risk of leakage. To disassemble the pump, by removing the motor and removing the coupling, the interior of the pump, including the actuator and the rotating part, can be pulled out through a hole in a separate slab. The pump is located on top of the container and the tube is welded to the bowl in place so that no liquid spills.

When the liquid has radioactivity it is necessary to protect the person from the liquid remaining in the extraction section of the pump.

Finally, the dimensions and features of one pump according to the present invention are as follows.

A vane wheel having a diameter of 90 mm and a thickness of 10 mm and including 24 vanes:-rotational speed of the drive shaft: 2900 / rpm; By the pump for pumping the coolant having a level of 6.5 m below the pump, a flow rate of 1500 l / hr is possible when the discharge level of water is 46 m, and a flow rate of 2000 l / hr is possible when the discharge level is 25 m.

These same wheels, when used in known centrifugal pumps, provide about four times lower total pressure lift.

Claims (5)

It is formed by a bowl fixed to the suction conduit and a discharge conduit, and a movable device which is formed to be pulled through the upper portion and is disposed with a high resistance to the bowl to form a suction chamber and a discharge chamber separated from each other, A vertical self-priming centrifugal pump positioned below, wherein the hydraulic part of the pump is constituted by a wheel having radial vanes driven by a drive shaft; The wheel is rotated between a base plate having a suction hole in communication with the suction chamber, and an upper partition having a groove in a circular shape on a side adjacent to the wheel; The circular groove is formed to have a semi-elliptical cross section and terminates in a hole for discharging liquid into the delivery chamber; The upper partition wall comprises a second hole located substantially on the same radius as the hole but closer to the axis, and a plate separating the hole from the opposite side of the wheel; A lower portion of the side wall of the movable device has a portion extending continuously with a portion of the groove. The self-priming centrifugal pump according to claim 1, wherein the tightness between the fixed bowl and the movable device is ensured by at least one metal piece respectively located in a groove provided in the side wall of the movable device. The outer radius Ra of the vane wheel, the outer radius Re of the groove, and the inner radius Ri of the groove,

Self-priming centrifugal pump, characterized in that to satisfy the inequality of. The self-priming centrifugal pump according to claim 1, wherein the delivery chamber is divided into two zones by a plate having a hole. 2. The self-priming centrifugal pump according to claim 1, wherein said tightness between said bowl and said movable device is ensured by packing around said drive shaft.

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