JPH06133527A - Electromagnetic pump - Google Patents

Abstract

PURPOSE:To provide an improved electromagnetic pump having no possibility of crack in the coil insulating material even if the pump is operated in high temperature environment. CONSTITUTION:In an electromagnetic pump in which a conduit is formed of a coaxial double pipe comprising an outside pipe 2 and an inside pipe 3 with a plurality of laminated cores 4 being arranged on the outer peripheral surface of the outside pipe 2 and on the inner peripheral surface of the inside pipe 3 and a plurality of annular coils 5 are fitted in slots 4a made at least in the laminated core block 4, the annular coil 5 is constituted by covering the outer periphery of coil conductors 10 with an insulator holding cover 13 and filling the gap between the coil conductor 10 and the insulator holding cover 13 with a power or granular insulating material 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic pump for applying a traveling magnetic field to a conductive fluid from the outside to cause a pumping action of the conductive fluid.

[0002]

2. Description of the Related Art Liquid sodium is usually used as a coolant in liquid metal cooled nuclear reactors. Liquid sodium is chemically active and, in liquid metal cooled reactors, 30
It is used at a high temperature of 0 to 600 ° C. In recent years, particularly in liquid metal cooled nuclear reactors, it is expected that an electromagnetic pump will be adopted as a coolant circulation pump and that the entire electromagnetic pump can be immersed in high temperature liquid sodium for use. If the entire electromagnetic pump can be immersed in the circulating coolant in this way, the coolant circulation system becomes compact and the degree of freedom in design increases. In addition, the efficiency of the conventional electromagnetic pump was as low as 20 to 30%, but since the electromagnetic pump can be placed in liquid sodium, all the losses converted into heat etc. generated in the pump are converted to liquid sodium. It will be absorbed and the efficiency of the whole system will be greatly improved.

In a liquid metal cooled nuclear reactor, an annular linear induction type electromagnetic pump using three-phase alternating current is generally used. The annular linear type electromagnetic pump has an annular flow passage, so ALIP (Annular Linear I
It is called a nduction pump) and has a high reliability and safety of the pipeline or duct structure, so it is especially suitable for large capacity reactor coolant circulation pumps. The basic structure and structural characteristics of the three-phase AC type annular linear electromagnetic pump will be described below with reference to FIG.

(1) The pipe line 1 is an outer pipe 2 made of stainless steel,
It is an annular flow path formed by a concentric double tube including an inner tube 3. The shape of the pipe line is annular, and it has excellent strength.
It can be said that the pipeline structure has high reliability.

(2) The stator has a laminated core block on the outer peripheral surface of the outer tube 2 with the laminating direction being the circumferential direction and the laminating surface being the conduit 1.
A plurality of stator cores 4 arranged radially to face the
And a large number of annular coils 5 fitted into the slots 4a of the stator core 4.

(3) A plurality of laminated core blocks for forming a magnetic circuit are arranged on the inner peripheral surface of the inner tube 3 so that the laminated direction is the circumferential direction and the laminated surface faces the conduit 1. The internal iron core 6 is stored. (4) The liquid metal 7a flows from the fluid inlet 7 to the fluid outlet 8.

(5) Since the entire electromagnetic pump is used by immersing it in liquid sodium, the outer casing 9 is covered with a gas having a high electrical insulation and a low activity such as nitrogen. Encapsulate. In addition, in an electromagnetic pump for circulating a large capacity coolant,
The inner iron core 6 is also provided with an annular coil to strengthen the magnetic force acting on the coolant.

When the three-phase induction type annular linear type electromagnetic pump having such a structure is used by being immersed in a high temperature coolant, heat loss generated in the coil 5, the pipe line 1, the iron core 4 and the iron core 6 is lost. Need to escape to the fluid. For example, heat loss generated in the coil 5 needs to be transferred from the coil 5 to the stator core 4 and from the stator core 4 to the outer tube 2 and the outer jacket 9 to allow heat to escape into the fluid. In order to have as low a thermal resistance as possible, the structures are designed to be in close contact with each other during operation. Next, of the structures of the electromagnetic pump as described above, the structure of the coil 5 will be described in more detail below with reference to FIGS. 4 and 5.

The coil 5 includes a conductor 10 wound in a required number of rings and provided with a heat-resistant electrical insulating material, and a ceramic system for covering the outer peripheral surface of the conductor 10 to form a main electrical insulating layer of the coil 5. And coil insulation material 11 of. In addition, as shown in FIG. 4, in the case of a three-phase induction type electromagnetic pump, three
The coil lead terminal 12 is pulled out from the place.

When used as a coolant circulation pump in a liquid metal cooled nuclear reactor, the coils assembled at room temperature are used in various high temperature environments of 300-600 ° C during operation. On the other hand, in order to increase the output of the electromagnetic pump,
The current passed through the coil must be increased, and therefore the allowable temperature rise of the coil is required to be as large as possible. In the coil of the conventional electromagnetic pump, copper or copper alloy is used as the coil conductor 10. Also,
Electromagnetic pumps used for coolant circulation pumps in liquid metal cooled nuclear reactors operate in high temperature environments of 300 to 600 ° C, so organic materials cannot be used as the coil insulation material 11, and ceramic-based materials and Mineral materials such as mica are used. The coefficient of thermal expansion of copper or copper alloy used as the coil conductor 10 of the electromagnetic pump is about 13 to 15 × 10 ⁻⁶ / ° C., while the coefficient of thermal expansion of the ceramic material used as the coil insulating material 11 is 3 to It is about 5 × 10 ^-6 / ° C. Therefore, when the coil assembled at room temperature is incorporated for use in an electromagnetic pump and operated, the amount of expansion due to thermal expansion of the coil conductor 10 becomes larger than the amount of expansion due to thermal expansion of the coil insulating material 11 when the temperature becomes high. Therefore, the occurrence of cracks in the coil insulating material 11 or peeling of the insulating layer may result in a loss of the electrical insulating function such as a decrease in the dielectric breakdown voltage.

[0011]

As described above, in the conventional electromagnetic pump, the expansion amount due to the thermal expansion of the coil conductor becomes higher than the expansion amount due to the thermal expansion of the coil insulating material at the time of high temperature. There is a possibility that the coil insulating material may be cracked or the insulating layer may be peeled off to lower the dielectric breakdown voltage and lose the electrical insulating function.

[0012]

DISCLOSURE OF THE INVENTION According to the present invention, a conduit is formed by a concentric double pipe consisting of an outer pipe and an inner pipe, and a laminated core block is formed on the outer peripheral surface of the outer pipe and the inner peripheral surface of the inner pipe. In the electromagnetic pump in which a plurality of laminated coils are arranged such that the laminating direction is the circumferential direction and the laminating surface faces the pipeline, and a large number of annular coils are inserted into slots provided in at least one of these laminated core blocks, the coils are The outer periphery of the coil conductor is covered with an insulating material holding cover, and a powdery or granular insulating material is filled between the coil conductor and the insulating material holding cover.

[0013]

The present invention has the above-mentioned structure, and by filling the powder conductor or the granular insulating material between the coil conductor and the insulating material holding cover, when the temperature becomes high, the coil conductor expands due to thermal expansion. The amount of the powder insulating material is absorbed by the appropriate movement of the powder insulating material to prevent excessive stress from being applied to the insulating material holding cover and the coil insulating material composed of the powdery or granular insulating material. It is possible to prevent cracks from occurring in the.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an electromagnetic pump according to the present invention will be described below with reference to FIGS. FIG. 1 shows a conceptual diagram of the structure of a coil used in an annular linear type electromagnetic pump operated in a high temperature environment such as a coolant circulation pump of a liquid metal cooling type nuclear reactor, and FIG. 2 shows A- of FIG. The arrow sectional drawing which follows the A line is shown. The coil 5 has a required number of coil conductors 10 made of heat-resistant insulated copper or copper alloy wound in an annular shape, and its outer peripheral surface is covered with an insulating material holding cover 13 made of a ceramic material. . Then, between the coil conductor 10 and the insulating material holding cover 13, a powder using a ceramic powder having excellent heat resistance such as magnesium oxide, aluminum oxide, zirconium oxide, or silicon nitride, which can withstand use in a high temperature environment. The body-shaped insulating material 14 is filled. Further, the outside of the insulating material holding cover 13 is wound with a protective tape 15 made of a ceramic material. The coil 5 is shown in FIGS. 2 (a) and 2 (b).
As shown in FIG. 5, the coil conductor 10 wound in an annular shape is housed together with the powdery insulating material 14 in an annular insulating material holding cover container 13a having a U-shaped cross section. Then, cover it with an annular insulating material holding cover lid 13b from above,
It is manufactured by winding a protective tape 15 on the surface thereof as shown in FIG. In the case of the three-phase induction type electromagnetic pump, the coil lead terminals 12 are drawn out from three places of the coil.

Next, the operation of this embodiment will be described.
As described above, the electromagnetic pump of the present invention is used in a high temperature environment as a coolant circulation pump for a liquid metal cooled nuclear reactor, for example. The coefficient of thermal expansion of the copper or copper alloy used as the coil conductor 10 is about 13 to 15 × 10 ⁻⁶ / ° C., while the coefficient of thermal expansion of the ceramic material used as the coil insulating material is 3 to 5 × 10 ^−. It is about ⁶ / ° C. Therefore, in the conventional state where the two are in close contact with each other, the amount of expansion due to the thermal expansion of the coil conductor 10 becomes larger than the amount of expansion due to the thermal expansion of the coil insulating material when the temperature becomes high, and the conventional coil has cracks in the coil insulating material. May occur. However, when the coil according to the present invention is used, by filling the powdery insulating material 14 between the coil conductor 10 and the insulating material holding cover 13, the expansion due to the thermal expansion of the coil conductor 10 becomes high when the temperature becomes high. Insulating material holding cover arranged on the outer peripheral surface
Since the particles of the powdery insulating material 14 can move appropriately even when the expansion amount of the powdery insulating material 13 is larger than that of the coiled material 13, the powdery insulating material 14 absorbs the expansion amount of the coil conductor 10 due to the thermal expansion. Excessive stress is not applied to the insulating material holding cover 13. Further, the coil insulation composed of the two layers of the insulating material holding cover 13 and the powdery insulating material 14 can prevent the coil insulating material from being cracked. Although the coil in the above-described embodiment has been described as being inserted into the outer core, that is, the laminated core block on the outer peripheral surface of the outer pipe, the inner core, that is, the laminated core block on the inner peripheral surface of the inner pipe, has been described. The same applies to the inserted coil.

[0016]

As described above, the electromagnetic pump of the present invention does not cause cracks in the insulating material of the coil even when used in a high temperature environment. Therefore, when used as an electromagnetic pump, the safety of the plant is improved. The practical effect is great.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view of a coil applied to an embodiment of an electromagnetic pump according to the present invention.

2A is a sectional view taken along the line AA of FIG.
FIG. 2B is an explanatory view illustrating the manufacturing process in FIG.

FIG. 3 is a perspective view showing a conventional example of an annular linear electromagnetic pump.

4 is a partially cutaway perspective view showing a coil of the electromagnetic pump shown in FIG.

5 is a sectional view taken along the line BB of FIG.

[Explanation of symbols]

 1 ... Pipe line 2 ... Outer pipe 3 ... Inner pipe 4 ... Stator core 4a ... Slot 5 ... Coil 6 ... Inner core 7 ... Fluid inlet 7a ... Liquid metal 8 ... Fluid outlet 9 ... Envelope 10 ... Coil conductor 11 ... Coil Insulating material 12 ... Coil lead terminal 13 ... Insulating material holding cover 13a ... Insulating material holding cover container 13b ... Insulating material holding cover lid 14 ... Powder insulating material 15 ... Protective tape

Claims (1)

[Claims] 1. A pipe path is formed by a concentric double pipe consisting of an outer pipe and an inner pipe, and a laminated core block is laminated on the outer peripheral surface of the outer pipe and the inner peripheral surface of the inner pipe in a circumferential direction. In an electromagnetic pump in which a plurality of laminated surfaces are arranged so as to face a pipeline, and a plurality of annular coils are fitted in slots provided in at least one of the laminated iron core blocks, the coils are made of an insulating material around the outer circumference of the coil conductor. An electromagnetic pump characterized in that it is covered with a holding cover, and a powdery or granular insulating material is filled between the coil conductor and the insulating material holding cover.