JPS6212371A - Method and device for controlling flow rate of conductive fluid - Google Patents

Abstract

PURPOSE:To simplify the structure and to enhance the reliability by automatically controlling a brake force which acts on fluid in response to the fluid temperature. CONSTITUTION:Two conductive electrodes 5 and two permanent magnets 6 are opposed elevationally and laterally to form a rectangular duct, and to feed conductive fluid 7 therein. The direction of a magnetic field 8 of a permanent magnet 6 is crossed perpendicularly to the flowing direction, a current circuit 9 is provided between the electrodes 5, and a resistor 10 is associated. Then, a current 11 is generated in the fluid 7, and a brake force F depending upon a magnetic flux density B and a resistance (r) acts on the fluid 7. In this case, since the flow rate of the fluid 7 varies according to the magnitude of the force F [the magnitudes of the resistance (r) and the density B], the resistor 10 which varies in the resistance (r) by the temperature of the fluid 7 is associated in the circuit 9 or a magnetic material which varies in the magnetization rate is associated in the circuit to control the force F. Thus, when the temperature of the fluid 7 rises, the force F acting on the fluid 7 decreases to increase the flow rate.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is directed to a device that heats (or cools) a conductive fluid such as a liquid metal and causes it to flow, in which the flow rate of the fluid is controlled according to the temperature of the fluid. It is related to the device.

[Background of the invention]

Conventionally, in fast breeder reactors that handle liquid metal sodium, for example, when heating (cooling) fluid (sodium), the temperature of the fluid is constantly monitored and the flow rate of the fluid is increased or decreased according to temperature changes. functionality is required. One example is the function of controlling the flow rate through the reactor core. In this case, a control function is required that constantly monitors the core exit temperature and increases the flow rate in the core and lowers the exit temperature when the core exit temperature rises. Another example is the temperature control function of a cold trap. A cold trap cools sodium to a certain temperature to solidify and remove impurities in the sodium, but if the sodium is cooled too much, there is a risk that the sodium itself will solidify and block the flow path. To prevent this freezing, the cold trap requires a control function that constantly monitors the condenser outlet temperature and increases the sodium flow rate to restore the sodium temperature when the sodium temperature approaches the freezing point.

In order to obtain the above-described control functions, a control device as shown in FIG. 4 has conventionally been used. In this device, the outlet temperature of the heater (cooler) 1 is measured with a thermometer such as a thermocouple.
The temperature signal is fed back to the conductive fluid 7 , sodium flow controller 4 , via the cut unit 3 . An electric valve or an air-operated valve is used as the flow rate control lI4, and the opening degree of the valve can be adjusted according to the outlet temperature.

However, in the conventional control device, the temperature gauge 2° actuator 3. The flow rate controller 4 and electrical wiring connecting these are required, and the configuration of the device is complicated. Further, since the flow rate controller 4 uses equipment having movable parts such as valves, its operation has low reliability and the flow rate has poor responsiveness to temperature changes.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable flow control device that eliminates the drawbacks of the conventional devices described above, has a simple structure, and has no moving parts.

[Summary of the invention]

The present invention applies a magnetic field to the conductive fluid from a direction having an angle with the flow direction of the conductive fluid.

-'-,, t<at least an induced current passing through the conductive fluid: 'In the method of generating an induced current passing through the conductive fluid, the magnitude of the resistance in the flow path of the induced current or the A method for controlling the flow rate of a conductive fluid, characterized in that the magnitude of the induced current is adjusted by adjusting the magnitude of the magnetic field, and an apparatus for implementing this method.

[Embodiments of the invention]

FIG. 5 shows the principle of the present invention, in which two conductive electrodes 5 and two permanent magnets 6 are arranged facing each other vertically and horizontally to form a rectangular duct. A conductive fluid is allowed to flow within this rectangular duct. The direction of the magnetic field 8 created by the permanent magnet 6 is perpendicular to the flow direction of the fluid 7. A current circuit 9 is provided between the two electrodes 5, and a resistor 10 is incorporated therein.

Considering magnetohydrodynamically, a conductive fluid 7 moves inside a magnetic field 8.
crosses at right angles, there is a current 11 in the fluid, a magnetic field 8,
occurs perpendicular to the flow direction of the fluid 7. The magnitude of this current 11 is expressed by the following equation.

Here, U: flow velocity (m/s), vector B: magnetic velocity density (
W/rI? ) , Vector Q: Distance between electrodes (m) r: Resistance in the current circuit (Ω) When the magnetic field 8 and the current 11 exist perpendicularly in a conducting current fluid in this way, according to Fleming's left-hand rule, Electromagnetic force F acts. That is, F=iXB
...(2) Substituting equation (1) into the above equation, r r equation (3)
As shown, the direction of the electromagnetic force F acting on the fluid is opposite to the fluid flow direction (flow velocity vector), and its magnitude depends on the magnetic flux density B and the resistance r in the current circuit. In other words, the magnitude of the braking force acting on the fluid depends on the magnetic flux density B and the resistance r, that is, the magnitude of the braking force acting on the fluid varies depending on the resistance r of the current circuit and the magnitude of the magnetic flux density B. The braking force is controlled by incorporating a resistor 10 whose electric resistance r changes into the current circuit 9, or by incorporating a magnetic material whose magnetic susceptibility changes depending on the fluid temperature into a part of the magnetic circuit. FIG. 5 shows an example in which a resistor lO having a positive gradient with respect to temperature is incorporated into the current circuit 9. In this case, as the temperature of the fluid increases, the electrical resistance r increases and the current i flowing through the current circuit 9 decreases.

Therefore, the braking force F acting on the fluid decreases, and as a result, the flow rate increases. Conversely, when the temperature of the fluid decreases, the electrical resistance decreases, resulting in an increase in current value and an increase in braking force.

The present invention will be explained in detail below using more specific examples. As shown in FIGS. 6 and 7, the first embodiment of the present invention
Two electrodes 5 are placed vertically facing each other, and two electrically insulating walls 12 are placed left and right.

The conductive fluid 7 is made to flow in a rectangular duct surrounded by these electrodes and an insulating wall. A permanent magnet 6 is arranged outside the insulating wall 12 so that a direct current magnetic field 8 enters at right angles to the flow direction of the fluid 7.

The two electrodes 5 are provided with a current circuit 9, a part of which
A resistor 10 is incorporated. As this resistor 1o, a resistor 1o is selected whose electrical resistance value changes greatly depending on the temperature.In order to change the resistance value according to the temperature of the fluid, the resistor 10 is either embedded in the electrically insulating wall 12 or Install it by inserting it directly inside. In the example shown in Figure 7,
A resistor 10 is embedded in an insulating wall 12. In this case, when the temperature of the fluid increases, the temperature of the electrically insulating wall 12 also increases due to heat conduction, and as a result, the electrical resistance value changes. The insulating walls 12 provided on the left and right electrically insulate the resistor 10 from the fluid 7, and allow all of the current generated in the fluid to flow perpendicularly to the flow direction of the fluid 7 and the magnetic field 8 to the surrounding area. serves to reduce leakage current. This reduces the amount of current that becomes ineffective for generating braking force.

As the resistor 10, choose one with different temperature characteristics depending on the purpose of use. Figure 8 shows the typical temperature characteristics. No. 81! Curves $1 and ■ have a positive gradient with respect to temperature, and are used when it is desired to flow more fluid as the fluid temperature increases. Among these, curve l
Curve 1 is used when you want to continuously increase the flow rate.Curve 1 is used when you want to keep the temperature unchanged until a certain temperature, but when you want to suddenly increase the flow rate once that temperature is reached. These resistor materials include:
The following types are available depending on the operating temperature range.

In Figure 8, the curve ■ has a negative slope with respect to temperature,
Used when it is desired to reduce the flow rate as the temperature of the fluid increases. Conversely, it is used when it is desired to increase the flow rate as the fluid temperature decreases. For example, it may be used to prevent freezing of a cold trap as described above. As this type of resistor material, the following materials are available in the temperature range from room temperature to 700°C.

FIG. 9 shows a second embodiment of the present invention. In this case, a rectangular duct 13 is made of a conductive material, and resistors 10 are arranged on the left and right inner surfaces of the duct. The conductive fluid flows inside the rectangular duct 13 while contacting the resistor 10. Permanent magnets 6 are arranged on the left and right outer sides of the rectangular duct so that a magnetic field 8 passes through at right angles to the flow direction of the fluid 7. As a result, as in the previous embodiment, a current 11 is induced in the fluid, and a braking force is applied in a direction opposite to the flow direction. As the resistor 10, one is selected whose electrical resistance value changes sensitively to changes in fluid temperature.

For example, a case will be described in which a resistor whose resistance value decreases (indicates conductivity) as the fluid temperature increases is attached.

Since the resistor 10 has a high electrical resistance while the fluid temperature is low, the resistor 10 acts like a kind of electrical insulation wall.
Therefore, the current 11 induced in the fluid is as shown in FIG.
As shown by the straight line, it flows straight up in the fluid and goes around the conductive duct 13 as a current circuit. In this case, all the currents in the fluid are perpendicular to the magnetic field 8, so the braking force is large. However, as the temperature of the fluid increases, the electrical resistance of the resistor 10 decreases and it becomes a conductive wall. come. For this reason, the current induced in the fluid does not flow vertically, as shown by the dotted line, but sinks into the side wall from the middle, so the current component perpendicular to the magnetic field 8 decreases.
The braking force will also decrease. On the other hand, if a resistor whose resistance increases as the temperature rises is used, the flow rate can be reduced in response to the rise in temperature.Using this embodiment, the duct 13 can also serve as a current circuit. , the device can be made more compact. In this embodiment, the resistor 10 is in direct contact with the fluid, so when handling highly corrosive fluids such as sodium, the surface of the resistor 10 should be covered with a thin metal foil or covered with nickel metal, etc. It is best to use it by vapor deposition.

A third embodiment is shown in FIGS. 1, 2, and 3.

In this embodiment, one circular pipe duct 13 and a cylindrical permanent magnet 6
Consisting of The permanent magnet 6 is a circular tube 14 made of stainless steel.
The 0-circular tube 14, which is enclosed with its magnetic poles facing each other, is arranged on the central axis of the duct 13. The duct 13 is made of ferromagnetic material. In this case, the lines of magnetic force spread radially from the N pole in the circular tube 14 to the outer duct 13, penetrate into the wall of the duct 13, and then return centripetally toward the S pole in the circular tube 14, as shown by the dotted line. get into the target. The magnetic pole of the permanent magnet is (
NN), (SS), (NN)..., the magnetic field 8 either radiates out from the circular tube 14 or converges centripetally to the circular tube 14, and its strength is the same as that of the adjacent magnetic field. It appears as the sum of the magnetic field strengths created by two permanent magnets.

A resistor 10 whose resistance value changes depending on the temperature of the fluid is installed between the duct 13 and the circular pipe 14. The conductive fluid 7 flows in a semicircular flow path surrounded by a duct 13, a circular pipe 14, and a resistor 10. As shown in FIG. 1, the direction of the magnetic field 8 extends radially outward from the center of the duct 13. In addition, since it converges in a centripetal manner at the center of the duct,
It is perpendicular to the flow direction of the fluid 7.

As a result, a loop current 11 is induced in the fluid that is perpendicular to the magnetic field and the flow direction. The interaction between the loop current 11 and the magnetic field 8 causes a braking force F to act on the fluid. The direction of the magnetic field changes alternately along the flow, but as shown in equation (3), the direction of the braking force F is determined only by the direction of the flow, regardless of the direction of the magnetic field 8. Further, the magnitude of the braking force is proportional to the magnetic flux density B and the magnitude i of the loop current 11.

In this embodiment, a resistor 1o whose resistance value changes depending on the temperature is incorporated into a part of the bus through which the loop current 11 flows. With this configuration, when the fluid temperature becomes high, the resistor 1
The resistance value of 0 becomes high, and it becomes possible to reduce the loop current 11 and reduce the braking force. In addition, reverse control is also possible.

Note that in this embodiment, when the loop current 11 enters the wall of the duct 13 and flows within the duct wall, the braking force acting on the fluid decreases. For this reason, if this embodiment is used, in which an electrical insulating wall 12 is attached to the inner surface of the duct 13 to prevent the current in the fluid from entering the duct 13, the piping, etc. Easily attaches to tubular equipment. In addition, the permanent magnet 6 is a ferromagnetic duct 13.
Since the duct itself forms part of the magnetic circuit, it has the advantage of reducing leakage of magnetic fields to the outside.

A fourth embodiment of the present invention is shown in FIGS. 10 and 11. In this example, the permanent magnet 6 is placed outside the duct 13, and the ferromagnetic material 15 is placed in the center of the duct 13. The permanent magnet 6 has magnetic poles in the axial direction of the duct 13 (NN, SS, NN/
) are placed facing each other. The ferromagnetic material 15 in the center of the duct is made of a ferromagnetic material plate as shown in Figs. 10 and 11.
As shown in the figure, they are laminated radially and sealed in a circular tube 14. This circular pipe 14 and duct 13 are
Made of a material with high magnetic permeability, such as stainless steel. In this example as well, the direction of the magnetic field 8 is the same as in the previously described embodiment (FIG. 1), as shown by the dotted line. However, the magnetic field lines originate from the north pole of the outer permanent magnet, penetrate the duct 13, cross the fluid at right angles, and enter the ferromagnetic body 15 in the center.

Why was the ferromagnetic material 15 laminated radially?

This is to make it easier for the magnetic field in the fluid to spread radially.

In this embodiment as well, a resistor 10 is incorporated between the duct 13 and the central circular tube 14 as in the previous embodiment (FIG. 1). The conductive fluid 7 is configured to flow through a semicircular space surrounded by the central circular pipe 14 of the duct 13 and the resistor 10. The method of controlling the braking force is the same as in the other embodiments described above. Note that when this embodiment is used, the permanent magnet 6
It has the advantage of being easy to assemble and repair.

In six embodiments, a fifth embodiment of which is shown in FIGS. 12, 13, and 14, electromagnets are used instead of permanent magnets. The configuration and operation are almost the same as the embodiment shown in FIG.

The duct 13 is made of ferromagnetic material, and the electromagnet 16 is placed in the center of the duct 13.
It is arranged. The electromagnet consists of a coil 18 wound around an iron core 17 arranged at equal intervals. Each iron core 17
The directions in which the coils are wound around the iron core are alternated in order to make the magnetic poles generated in the iron core face each other in the manner (NN, SS, NN, SS...). The coil 18 is surrounded from the outside by a circular tube 14 made of stainless steel. In addition, the coil 1 wound around the iron core 17
A material whose resistance value is sensitive to changes in surrounding temperature is used as the material of No. 8. In addition, a DC power supply 20 is used as an excitation power supply.
Use. As a result.

When the temperature of the liquid rises and the temperature around the coil increases,
The resistance of the coil increases and the excitation current 19 decreases. Therefore, the strength of the magnetic field, that is, the magnetic flux density B, decreases and the braking force decreases, and vice versa. When this embodiment is used, since a temperature-sensitive resistor is used in the excitation coil itself, there is an advantage that the configuration is simple.

The sixth embodiment is shown in FIGS. 15 and 16. In this example,
An electromagnet 16 is used instead of the permanent magnet used in the embodiment shown in FIG. A ferromagnetic material 15 is placed on the outside of the duct 13, and a coil 18 is wound inside the ferromagnetic material 15.The cross section of the ferromagnetic material 15 is cut into a comb shape, and the coil 18 is inserted into the concave part.

It is wound in the circumferential direction of the duct 13. The purpose of this comb-like shape is to make it easier for the magnetic field 8 to enter the duct 13 radially from the convex portion of the comb, as shown by the dotted line in FIG. Further, in order to make the magnetic flux distribution in the circumferential direction inside the duct 13 uniform, no notch is provided in the circumferential direction of the ferromagnetic material 15.
A circular tube 14 similar to that of the embodiment shown in FIG. 7 is arranged on the central axis of the duct 15, and a ferromagnetic material 15 laminated radially is enclosed within the circular tube 14. As the coil 18, a coil whose resistance value changes sensitively depending on temperature is selected.

Similar to the embodiment of FIG. 8, when the temperature of the fluid 7 increases,
The resistance of the coil 18 increases and the excitation current 19 decreases. Therefore, the strength of the magnetic field 8 is reduced, and the braking force is reduced. The reverse control is also possible.

FIG. 17 shows a seventh embodiment, which is a modification of the embodiment shown in FIG. Two conductive electrodes 5 are arranged vertically and two permanent magnets 6 are arranged horizontally facing each other. A single coil 19 connects between the two electrodes 5,
A portion of the coil 19 is wound around the permanent magnet 6. For this coil 19, choose one whose resistance value changes sensitively when the temperature changes.In this embodiment, the fluid 7
The magnetic flux density B of the magnetic field 8 inside is the sum of that due to the permanent magnet 6 and that due to the electromagnet generated when a current flows through the coil 19. -Simply put, when a coil is wound around a permanent magnet and a current i is passed through the coil, the magnetic flux density B becomes the first
It changes as shown in Figure 8.

The magnetic flux density B when the current i is 0 is the magnetic flux density of the permanent magnet itself, and increases by ΔB when the current i is applied.

p) 1, ','',,': i$ In the embodiment shown in Fig. 17, fluid 7
Assuming that the temperature of '-h'a increases, the temperature of the coil wound around the permanent magnet 6 increases, and the electrical resistance value increases. For this reason, the current i flowing through the coil 19 decreases, and the increase in magnetic flux density AR also decreases, as can be seen from equation (2).

When current i and magnetic flux density B decrease simultaneously, braking force F
decays faster than when only either the current or the magnetic flux density decreases. That is, in this embodiment, since the synergistic effect of the current i and the magnetic flux density B is used, the responsiveness of the flow rate control to the temperature change of the fluid becomes faster.

Above, we have described an example in which a resistor is used in which the electrical resistance and therefore the current in the fluid changes when the temperature of the fluid changes.However, when the temperature of the fluid changes, the magnetic flux density B
It is also possible to consider an embodiment in which the values are changed. This can be done by incorporating a substance whose magnetic properties change depending on temperature into a part of the magnetic circuit through which the fluid passes. For example, Figures 1 and 6
In the illustrated embodiment, the permanent magnet 6 is made of a material whose coercive force changes with temperature (for example, MnFe104
? An example may be where CoFez()4*NiHCo, etc.) is selected. Also, in place of the ferromagnetic material 15 placed in the center of the duct 13 in FIGS. 10 and 13,
An example is possible in which a material whose magnetic susceptibility changes sensitively depending on temperature (for example, a rare earth iron garnet ferromagnetic material) is attached. In either example, the magnitude of the magnetic flux density B perpendicular to the fluid changes with the fluid temperature, which modulates the braking force.

Naturally, a resistor whose resistance value changes depending on the fluid temperature may be incorporated into the current circuit, and at the same time, a substance whose magnetic properties change depending on the fluid temperature may be incorporated into the magnetic circuit.
In this case, as mentioned above, a synergistic effect of the current and the magnetic field makes it possible to create a flow control device with quick response.

19 and 20 show an example in which a flow rate control device according to the eighth embodiment of the present invention is attached to a device for heating (or cooling) a conductive fluid. It is attached to the outlet piping. In the heater 1, the conductive fluid 7 is heated by the heater 22, but due to some abnormality,
When the temperature of the fluid at the outlet of the heater 1 becomes high, the electromagnetic braking force of the flow rate control device 21 is weakened, acting to increase the flow rate of the fluid. This can prevent excessive fluid heating accidents.

FIG. 21 shows a ninth embodiment, which has the same operating principle as the embodiment shown in FIG. However, the structure is simpler. A permanent magnet 6 is incorporated between the upper and lower two conductive electrodes 5. An insulating wall 12 is attached to the inner surface of the permanent magnet 6.

The conductive fluid 7 flows perpendicularly to the plane of the paper as in FIG. As the permanent magnet 6, as shown in FIG. 22, a permanent magnet is selected that has the characteristics that as the temperature increases, the holding force B0 of the permanent magnet decreases and the electric resistance r increases.
While the fluid temperature is low, the holding force B0 is large and the resistance is small, so the magnitude i of the induced current 11 is large. Therefore,
The electromagnetic braking force is large, but as the fluid temperature increases, the holding force B decreases and the resistance increases (the current value i decreases), so the electromagnetic braking force decreases.

In this way, by using a substance in which the coercive force B0 and the resistance value r change simultaneously, the structure can be obtained by a simple (Pb) substitution method.

〔Effect of the invention〕

As described above, according to the present invention, since the braking force acting on the fluid can be automatically controlled according to the fluid temperature, a self-control type flow rate control device can be provided. Further, there is no need for a thermometer, an actuator, or a controller for flow rate control, which greatly simplifies W construction. Furthermore, since there are no moving parts such as valves, the reliability of the device itself is high and the responsiveness of flow rate control to temperature changes is fast. Therefore, the present invention can improve the reliability of plants that handle conductive fluids and contribute to cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a duct according to a third embodiment of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, FIG. 3 is a schematic perspective view of the duct in FIG. 5 is a perspective view showing the basic structure of the present invention. FIG. 6 is a perspective view of a duct according to the first embodiment of the present invention.
6 is a cross-sectional view of the duct shown in FIG. 6, FIG. 8 is a graph of the temperature-electrical resistance characteristic of the resistor shown in FIG. 7, and FIG. 9 is a sectional view of the duct according to the second embodiment of the present invention. 10 is a cross-sectional view of a duct according to a fourth embodiment of the present invention, FIG. 11 is a cross-sectional view taken along the line B-B in FIG. 10, and 12rM is a cross-sectional view of a duct according to a fifth embodiment of the present invention. 13 is an enlarged sectional view of the main part of FIG. 12, FIG. 14 is a vertical sectional view of FIG. 12, and FIG. 15 is a partially cutaway perspective view of a duct according to a sixth embodiment of the present invention. , FIG. 16 is a cross-sectional view of the duct in FIG. 15, FIG. 17 is a cross-sectional view of the duct according to the seventh embodiment of the present invention, and FIG. 18 is a graph showing the current flowing through the coil and the magnetic flux density of the magnet in FIG. FIG. 19 is a graph diagram showing the relationship between the above and FIG. 19, which is an eighth embodiment of the present invention, and FIG. is a sectional view taken along the line C-C in FIG. 19, FIG. 21 is a sectional view of a duct according to the ninth embodiment of the present invention, and FIG. 22 is a variation relationship between resistance value and holding force with respect to temperature in FIG. 21. FIG. 1... Heater, 5... Electrode, 6... Permanent magnet, 7
... Conductive fluid, 8... Magnetic field, 9... Current circuit,
DESCRIPTION OF SYMBOLS 10... Resistor, 11... Current, 12... Insulating wall, 13... Duct, 14... Inner tube, 16... Electromagnet, 17... Iron core, 18... Coil , 19... Excitation current, 20... DC power supply, 22... Heater.

Claims (1)

[Claims] 1. From a direction having an angle with the flow direction of the conductive fluid,
In the method of generating at least an induced current passing through the conductive fluid by applying a magnetic field to the conductive fluid, the magnitude of the resistance in the flow path of the induced current or the magnetic field depends on the temperature of the conductive fluid. 1. A method for controlling the flow rate of a conductive fluid, comprising adjusting the magnitude of the induced current. 2. A device comprising a magnetic field generation circuit and a conductive fluid flow path installed in a magnetic field generated by the magnetic field generation circuit so that its flow direction forms an angle with the direction of the magnetic field,
At least one of the flow path of the induced current generated in the conductive fluid, the magnetic field generation circuit, or the magnetic flow path created by the magnetic field generation circuit is arranged to undergo a temperature change of the conductive fluid. 1. A conductive fluid flow rate control device characterized by interposing a material whose electrical resistance changes depending on temperature. 3. In an apparatus comprising a magnetic field generation circuit and a conductive fluid flow path installed in a magnetic field generated by the magnetic field generation circuit so that the flow direction forms an angle with the direction of the magnetic field, the magnetic field generation circuit A material whose magnetic properties change depending on the temperature is interposed in at least one of the circuit or the magnetic flow path created by the magnetic field generating circuit, in a position where the conductive fluid undergoes temperature changes. conductive fluid flow control device. 4. In claim 2, at least one of the magnetic field generation circuit and the magnetic flow path formed by the magnetic field generation circuit is arranged to undergo temperature changes of the conductive fluid, A conductive fluid flow rate control device characterized by intervening a material whose magnetic properties change.