JP2004048894A - Preheating method of non-cooled electromagnetic pump for liquid metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preheating method of a non-cooled electromagnetic pump for liquid metal, for maintaining the healthiness of the electromagnetic pump in preheating for charging the liquid metal, and attaining high safety and efficiency. <P>SOLUTION: This preheating method of the non-cooled electromagnetic pump for liquid metal has a duct forming a liquid metal passage; an electromagnetic coil; an iron core; a support structure for supporting the iron core; and a casing for sealing the electromagnetic coil, the iron core, and the support structure. In preheating the electromagnetic pump to charge a liquid metal, since the temperature rise rate at the time of preheating the duct, the electromagnetic coil, the iron core, the support structure, and the casing is set at ≤ 20 °C per hour, the temperature differences between the duct and the casing, and between the duct and the support structure can be restrained, thus preventing breakage to the support structure. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an uncooled electromagnetic pump applied as a coolant main circulation pump of a liquid metal cooled fast reactor and a method of preheating an uncooled electromagnetic pump for flowing liquid metal.
[0002]
[Prior art]
A conventional electromagnetic pump is a cooling type, and a cooling type electromagnetic pump is installed on an outer peripheral side of a duct, and an insulating material is provided between the duct, an iron core, and a coil. Therefore, even at the time of preheating in which the pipe is heated by the heater to fill the liquid metal, the temperature rise from the duct is shut off, and the temperature of the internal structure of the cooling type electromagnetic pump does not rise. Because there is no temperature difference between the duct and the casing, and between the duct and the supporting structure supporting the iron core, the cooling type electromagnetic pump uses the temperature difference between the duct and the casing, between the iron core and the supporting structure, and between the duct and the supporting structure. There was no need to consider the damage due to.
[0003]
However, an uncooled electromagnetic pump is installed immersed in liquid metal, and the Joule heat of the electromagnetic coil, the internal structure of the electromagnetic pump, and the heat generated by the eddy current of the duct and the eddy current of the iron core, make the electromagnetic coil sound and the core and In order to maintain the function of the supporting structure, heat is radiated into the liquid metal through the iron core, duct, internal gas and casing, but the non-cooling type electromagnetic pump is provided with insulating material between the duct, the iron core, and the coil that prevents this heat radiation. I didn't. However, at the time of preheating, the temperature of the duct rises due to the heating of the heater, and a temperature difference occurs between the duct and the support structure and between the iron core and the support structure. Further, at the time of preheating, the temperature of the casing hardly rises because there is no liquid metal, and a temperature difference occurs between the duct and the casing. Conventionally, no measures have been taken with respect to such a preheating method of the non-cooling type electromagnetic pump in consideration of the damage caused by the temperature difference between the duct and the casing, between the iron core and the support structure, and between the duct and the support structure.
[0004]
In a general three-phase induction type electromagnetic pump, three-phase windings are distributed and arranged in the order of each phase in the fluid flow direction and the axial direction of the electromagnetic pump. Then, a three-phase alternating current is passed through the three-phase winding to generate a traveling magnetic field in the flow direction of the current. By applying the so-called "Fleming's right-hand rule", an induced current is applied to the liquid metal, which is a conductive fluid. Shed. An interaction between the induced current and the traveling magnetic field generates an electromagnetic force, which acts as a force for flowing the liquid metal and acts as a pump. This electromagnetic force is the same as the torque generating force in the induction motor, the thrust in the linear motor, and the like. The three-phase induction type electromagnetic pump transfers liquid metal based on this principle.
[0005]
Here, a conventional electromagnetic pump will be described with reference to a partially cut-away perspective view of FIG. 5 and a cross-sectional view of FIG.
The electromagnetic pump 1 forms a concentric double duct structure with an outer duct 3 and an inner duct 4 in order to flow a conductive fluid 2 such as liquid metal, for example, liquid sodium. The conductive fluid 2 flows in an annular flow path 5 formed by the duct 4.
[0006]
Outside the outer duct 3, an outer iron core 6 in which a number of electromagnetic steel sheets are stacked is arranged in a circumferential direction. A large number of annular outer electromagnetic coils 8 are arranged in the axial direction in slots 7 formed at the outer duct side end of each outer iron core 6 so that the three-phase alternating current forms a traveling magnetic field. Is connected to The outer iron core 6 has a configuration in which end plates are provided at both ends in the circumferential direction of a large number of magnetic steel sheets, and the electromagnetic steel sheets are fixed by fixing tools inserted into holes provided in the circumferential direction of the outer iron core 6. Inside the inner duct 4, an inner core 9 formed by stacking a number of electromagnetic steel sheets is arranged in the circumferential direction, and a number of inner electromagnetic coils 13 are arranged in a slot formed in each inner core 4 in the axial direction. Have been.
[0007]
The electromagnetic pump 1 configured as described above supplies a three-phase alternating current to the outer electromagnetic coil 8 so that the conductive fluid 2 flows through the annular flow path 5 from the fluid inlet 10 which is a suction port, and is a discharge port. The fluid is transferred from the fluid outlet 11 to the outside. The internal heat generated by the Joule loss generated in the outer electromagnetic coil 8, the iron loss generated in the outer iron core 6, the heat input from the conductive fluid 2, and the like are transferred to the casing 12 disposed on the outer peripheral side of the outer iron core 6. Generally, heat is removed by circulating a refrigerant from the inside to the outside.
[0008]
[Problems to be solved by the invention]
In a system such as an uncooled electromagnetic pump that radiates the heat generated by the Joule heat of the coil, the eddy current of the iron core, and the eddy current of the duct to the liquid metal during normal operation, the internal structure of the electromagnetic pump is the same as during preheating without liquid metal The temperature distribution of the internal structure differs from that during normal operation, and there is a temperature difference between the duct and casing, between the iron core and the support structure, and between the duct and the support structure, and there is a possibility that the duct, casing and support structure may be damaged. is there.
[0009]
That is, in the conventional non-cooling type electromagnetic pump, the duct is heated by the heater at the time of preheating, but the casing and the supporting structure are not heated by the heater, and since the casing has no liquid metal around, the same level as the atmosphere. Although a slight temperature rise can be expected with the temperature of the duct or the temperature of the duct, there is a problem that a temperature difference between the duct and the casing and between the duct and the support structure tends to be larger than in the normal operation.
[0010]
The present invention has been made in order to cope with the above situation, and an object of the present invention is to maintain the integrity of an electromagnetic pump during preheating for filling a liquid metal, to provide a highly safe, efficient liquid metal non-cooling type excitation. An object of the present invention is to provide a method for preheating a pump.
[0011]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 includes a duct that forms a liquid metal flow path, an electromagnetic coil, an iron core, a support structure that supports the iron core, and a support structure that supports the electromagnetic coil and the iron core. In the method for preheating an uncooled electromagnetic pump for liquid metal having a casing that seals a structure, when preheating the electromagnetic pump to fill liquid metal, the duct, the electromagnetic coil, the iron core, the supporting structure, and the casing The temperature rise rate during preheating is set to 20 ° C. or less per hour.
[0012]
According to a second aspect of the present invention, in the method for preheating the non-cooling type electromagnetic pump for liquid metal according to the first aspect, the temperature difference between the duct temperature and the casing temperature is 100 ° C. or less in the heating process and at the end of the heating. The temperature difference between the temperature and the support structure temperature is limited to 50 ° C. or less, and the temperature difference between the duct temperature and the support structure temperature is limited to 80 ° C. or less.
[0013]
According to the first and second aspects, the preheating method is to suppress the temperature difference between the duct and the casing and between the duct and the support structure by gradually increasing the temperature rise rate of the duct. Can be prevented.
[0014]
According to a third aspect of the present invention, in the method for preheating a liquid metal non-cooling type electromagnetic pump according to the first or second aspect, Joule heat of the coil and eddy current of the iron core generated by applying an alternating current to the electromagnetic coil. And the eddy current of the duct is used as a heating source.
[0015]
According to the third aspect, when the electromagnetic coil is energized, an eddy current flows through the duct, the iron core, and the like. Therefore, since the duct generates heat due to the duct eddy current in addition to the heater heating, the duct temperature can be suppressed from rising.
[0016]
According to a fourth aspect of the present invention, in the method for preheating a non-cooling type electromagnetic pump for liquid metal according to the third aspect, the frequency for energizing the electromagnetic pump is set to a rated frequency or less.
According to the fourth aspect, since the AC current frequency is set to be equal to or lower than the rated frequency of the electromagnetic pump, the temperature rise of the duct is suppressed.
[0017]
According to a fifth aspect of the present invention, in the method for preheating a non-cooling type electromagnetic pump for liquid metal according to the third aspect, an alternating current supplied to the electromagnetic pump is set to 30% or less of a rated current.
According to the fifth aspect, the temperature increase of the duct is suppressed by setting the current supplied to the electromagnetic coil to 30% or less of the rated current.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an enlarged sectional view of a main part of an electromagnetic pump according to an embodiment (corresponding to claims 1 to 5) of the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG.
[0019]
In the electromagnetic pump 1, the outer core 6 is radially arranged around the outer duct 3, and the outer electromagnetic coil 8 is arranged so as to be axially sandwiched by the outer core 6. The iron core 6, the electromagnetic coil 8, and the support structure that supports the electromagnetic coil and the iron core are hermetically disposed in a casing 12. The material of the outer duct 3 and the casing 12 is a non-magnetic material which is hardly corroded by the conductive fluid (liquid metal) 2 and has a sufficient strength at a high temperature. The material of the iron core is a ferromagnetic material. Material is applied.
[0020]
Further, the radial support structure of the electromagnetic pump 1 of the present embodiment has a configuration in which both radial ends of the outer iron core 6 are sandwiched by side plates 14, and the pair of side plates 14 are sandwiched therebetween. A long alignment plate 15 extending along the axial direction is fitted to the projecting portions of the one outer core 6 and facing each other, and the opposed portions of the side plate 14 projecting portions are fitted and fastened by bolts 15a. ing. In order to make the thermal expansion of the side plate 14 and that of the alignment plate 15 the same, they are made of a material having the same thermal expansion coefficient, for example, the same material.
[0021]
Further on the outer peripheral side of the outer core 6, a frame 16 and a backing ring 17 for radially supporting from the outer peripheral surface side of the alignment plate 15 are arranged. The frame 16 and the backing ring 17 are fixed by bolts 17a, and a plurality of these are connected along the axial direction.
[0022]
Further, a radial spring plate 18 including a plurality of leaf springs is arranged on the back surface of the alignment plate 15. The radial spring plates 18 are fixed to the frame 16 by bolts 18a at the respective center portions, and both end portions elastically abut against a radial spring plate receiver 19 provided on the back surface of the alignment plate 15. Constitute a clamp mechanism. That is, the radial displacement between the outer core 6 and the alignment plate 15 is transmitted to the radial spring plate 18 via the radial spring plate receiver 19. Then, a reaction force is generated by the deformation of the radial spring plate 18, thereby forming a clamp mechanism.
[0023]
The electromagnetic pump 1 warms a pipe (duct) with a heater during preheating for filling the liquid metal 2. This heat is transferred to the iron core, the supporting structure, and the casing as the duct temperature rises. At this time, if the temperature of only the duct rises sharply due to the heating of the heater, the temperature of the iron core, the supporting structure and the casing does not follow, and the temperature between the duct temperature and the casing temperature, between the duct temperature and the iron core temperature, and between the duct temperature and the supporting structure temperature. There is a temperature difference between the two, and this temperature difference becomes a temperature at which the function of the internal structure cannot be maintained, and the duct, the casing, and the support structure may be damaged. In order to prevent such breakage, the rate of temperature rise with the internal structure is limited to ensure the soundness of the internal structure. That is, the internal temperature rise rate is set to 20 ° C./hour (0.3 ° C./minute) or less in order to gradually increase the core temperature, the electromagnetic coil temperature, the support structure temperature, and the casing temperature. Further, each temperature is monitored by a monitoring and control device so that each temperature becomes 20 ° C. or less, and when the temperature becomes 20 ° C. or more, ON / OFF control of a duct heater is performed by a control signal from the monitoring and control device. The temperature rise rate of the structure is controlled to be 20 ° C. or less per hour.
[0024]
Further, in the electromagnetic pump 1, the radial spring plate 18 deforms the alignment plate 15 on the back of the core to deform the spring plate 18 because Joule heat generated by the electromagnetic coil during the normal operation of the electromagnetic pump radiates to the liquid metal 2 through the iron core. It is pressed by the reaction force generated by. Further, the gap between the outer core 6 and the outer duct 3 tends to be wider during the operation of the pump than at the time of assembly. Therefore, the radial spring is preliminarily deformed at the time of assembly to generate a reaction force. When the system, that is, the duct piping is evacuated, an external pressure is applied to the duct, and the reaction force of the radial spring plate 18 that has been deformed in advance and the radial thermal expansion of the duct due to the heating of the heater are applied, which may cause the duct to buckle. is there. For this reason, the temperature difference between the duct temperature and the temperature of the supporting structure is controlled to 80 ° C. or less from the viewpoint of preventing duct buckling during system evacuation.
[0025]
Next, at one axial end (upper part in FIG. 1) of the outer iron core 6, the iron core retainer 20 is fixed to the alignment plate 15 by bolts (not shown). On the same end side of the frame 16, an upper holding plate 21 is fixed by bolts 21a. Further, the upper iron core presser 20 and the upper presser plate 21 are positioned in the circumferential direction and the radial direction by the key 22. An axial spring plate 24 made of an elastic plate is sandwiched and fixed between the outer surface of the upper holding plate 21 and the flange 23 of the frame 16 by bolts 23a. An axial spring plate receiver 26 mounted on the upper iron core retainer 20 is in contact with the axial spring plate 24.
[0026]
With such a structure, the axial displacement between the outer core 6 and the alignment plate 15 is transmitted to the axial spring plate 24 via the upper core retainer 20 and the axial spring plate receiver 26, and the axial displacement of the axial spring plate 24 is prevented. The deformation generates a reaction force, and constitutes a clamp mechanism. The axial spring plate 24 limits the temperature difference between the iron core temperature and the temperature of the supporting structure (the alignment plate is a part of the supporting structure) to 50 ° C. or less from the viewpoint of maintaining the stress.
[0027]
FIG. 3 is a vertical sectional view of the electromagnetic pump showing the fluid circulation according to the embodiment of FIG. As shown in the figure, the electromagnetic pump 1 has a bellows 28 installed above ducts 3 and 4, and connects the duct and the casing 12. The bellows 28 absorbs the thermal expansion displacement of the temperature of the casing 12 and the temperatures of the ducts 3 and 4.
[0028]
Next, the operation method of the present embodiment will be described.
Since the electromagnetic pump 1 is immersed in the liquid metal 2 during the normal operation of the electromagnetic pump 1, the temperature of the casing 12 also becomes substantially the same as the temperature of the surrounding liquid metal 2 like the duct, and the temperature difference between the duct temperature and the casing temperature. I can hardly get it. At the time of preheating, only the duct temperature rises, and the heat of the duct gradually transfers heat to the casing 12, but the temperature difference between the duct temperature and the casing temperature becomes larger during preheating than during normal operation. The axial thermal expansion of the duct is absorbed by the bellows 28 installed at the upper end of the electromagnetic pump 1 in the axial direction. However, if the temperature difference increases, the thermal expansion of the bellows 28 will be exceeded and the bellows 28 will be damaged. There is fear. In order to prevent the bellows 28 from being damaged, the temperature difference between the duct temperature and the casing temperature is controlled to 100 ° C. or less.
[0029]
In addition to heating the duct, a 3-phase alternating current is supplied to the electromagnetic coil, and the Joule heat of the electromagnetic coil, the eddy current of the iron core, and the heat generated by the eddy current of the duct are used to generate the temperature of the iron core, the supporting structure, and the casing 12. To rise. By applying a three-phase alternating current to the electromagnetic coil, the same effect as the presence of a heater inside the electromagnetic pump 1 is obtained, and the duct temperature and the core temperature, the duct temperature and the supporting structure temperature, the duct temperature and the casing 12 temperature are controlled. This has the effect of reducing the temperature difference. Further, by performing the temperature control by increasing the temperature of the internal structure, the temperature increase rate and the temperature difference restriction can be satisfied, and the preheating time can be shortened.
[0030]
When applying a three-phase alternating current to the electromagnetic coil, the duct also generates heat due to the eddy current, and the temperature difference between the duct temperature and each structure temperature increases. Therefore, the alternating current frequency is set to be equal to or lower than the rated frequency of the electromagnetic pump 1 from the viewpoint of suppressing a rise in the duct temperature.
[0031]
When a three-phase AC current is applied to the electromagnetic coil, the internal temperature of the electromagnetic pump 1 increases due to Joule heat of the electromagnetic coil and heat generated by eddy currents of the iron core and the duct. At this time, if the energizing current value is set to the rated current of the electromagnetic pump 1, the temperature rise rate of the internal structure may be higher than the duct temperature rise rate, and the temperature rise rate limitation and the temperature difference limitation are not satisfied. In order to satisfy the limitation of the temperature rise and the limitation of the temperature difference, the current supplied to the electromagnetic coil is set to 30% or less of the rated current, and the temperature of each structure during preheating is controlled.
[0032]
FIG. 4 shows a preheating characteristic diagram in which the outer stator portion of the electromagnetic pump is preheated in consideration of the above preheating method. From this preheating characteristic diagram, it can be seen that the soundness of the duct, the iron core, the supporting structure, and the casing can be sufficiently satisfied.
[0033]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent breakage of a duct, an iron core, a supporting structure supporting an iron core and an electromagnetic coil at the time of preheating for filling liquid metal, and to shorten a preheating time for filling liquid metal. Therefore, it is possible to provide a method for preheating a liquid metal non-cooling type electromagnetic pump that maintains the integrity of the electromagnetic pump at the time of preheating for filling the liquid metal, has high safety, and is efficient.
[Brief description of the drawings]
FIG. 1 is an enlarged view of a main part of an embodiment of the present invention.
FIG. 2 is a sectional view taken along the line II-II of FIG.
FIG. 3 is a longitudinal sectional view of the electromagnetic pump showing the fluid circulation according to the embodiment of FIG. 1;
FIG. 4 is a diagram showing a preheating characteristic of an outer stator portion of the electromagnetic pump.
FIG. 5 is a partially cutaway perspective view of a conventional electromagnetic pump.
FIG. 6 is a transverse sectional view of FIG. 6;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electromagnetic pump, 2 ... Conductive fluid (liquid metal), 3 ... Outer duct, 4 ... Inner duct, 5 ... Annular flow path, 6 ... Outer core, 7 ... Slot, 8 ... Outer electromagnetic coil, 9 ... Inner core Reference numeral 10: fluid inlet, 11: fluid outlet, 12: casing, 13: inner electromagnetic coil, 14: side plate, 15: alignment plate, 15a, 17a, 18a, 21a, 23a: bolt, 16: frame, 17: backing Ring, 18: radial spring plate, 19: radial spring plate receiver, 20: upper iron core retainer, 21: upper retainer plate, 22: key, 23: flange, 24: axial spring plate, 25: bolt, 26 ... Axial spring plate receiver, 27 ... tank, 28 ... bellows, 29 ... outer stator, 30 ... inner stator.

Claims (5)

Non-cooling type electromagnetic pump for liquid metal having a duct forming a liquid metal flow path, an electromagnetic coil, an iron core, a support structure for supporting the iron core, and a casing for sealing the electromagnetic coil, the iron core and the support structure In the preheating method, when preheating the electromagnetic pump to fill the liquid metal, the temperature rise rate at the time of preheating the duct, the electromagnetic coil, the iron core, the support structure, and the casing is set to 20 ° C. or less per hour. Characteristic method of preheating an uncooled electromagnetic pump for liquid metal. 2. The method for preheating a non-cooling type electromagnetic pump for liquid metal according to claim 1, wherein a temperature difference between a duct temperature and a casing temperature is 100 ° C. or less, and a temperature difference between an iron core temperature and a support structure temperature in a heating process and at the end of the heating. And a temperature difference between the temperature of the duct and the temperature of the supporting structure is set to 80 ° C. or less. 3. A method for preheating a non-cooling type electromagnetic pump for liquid metal according to claim 1 or 2, wherein a Joule heat of the coil, an eddy current of the iron core and an eddy current of the duct caused by applying an alternating current to the electromagnetic coil are heated. A method for preheating a non-cooling type electromagnetic pump for liquid metal, characterized in that it is used as a liquid metal. 4. The method for preheating a non-cooling type electromagnetic pump for liquid metal according to claim 3, wherein a frequency for energizing the electromagnetic pump is set to a rated frequency or less. 4. A preheating method for an uncooled electromagnetic pump for liquid metal according to claim 3, wherein an alternating current supplied to the electromagnetic pump is set to 30% or less of a rated current. Method.

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