JP2009130996A - Rotary field electromagnetic pump having function for preventing back flow - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve stabilized flow rate-delivery pressure characteristics by setting the thickness of a partially tubular channel in the radial direction and the operational conditions optimally. <P>SOLUTION: In a rotary field electromagnetic pump wherein a channel 5 on the inflow side is connected to one end side of a partially tubular channel 1, a channel 6 on the outflow side is connected to the other end side thereof, and inductors 2 and 2' forming a field which moves rotationally from the channel 5 on the inflow side toward the channel 6 on the outflow side in the circumferential direction of the channel 1 are arranged in the partially tubular channel 1, thickness of the channel 1 in the radial direction from the inner circumferential side to the outer circumferential side thereof is set such that the ratio of flux density ΦB/ΦA on the inner circumferential side and the outer circumferential side becomes 70% or more. Alternatively, thickness of the channel 1 is set such that the ratio of flux density ΦB/ΦA on the inner circumferential side and the outer circumferential side of the channel 1 becomes 55% or more, and the rotary field electromagnetic pump is operated such that the slip value becomes 0.97 or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a conductive fluid induction type electromagnetic pump of a type that conveys a conductive fluid, and forms a magnetic field that rotates and moves in a circumferential direction in a cylindrical flow path, thereby providing conductivity in the flow path. The present invention relates to a magnetic field rotating electromagnetic pump that gives thrust by electromagnetic induction to a fluid, and in particular has an Ω-shaped flow channel in which an inflow channel and an outflow channel are connected to both ends of a partially cylindrical flow channel. .

  In a drive pump that applies a thrust to a conductive fluid such as molten metal and conveys it, a mechanical impeller is driven by rotating an impeller driven by a motor outside the flow path through a sealed bearing. An electromagnetic pump that applies a thrust to the conductive fluid and an electromagnetic field that does not require a seal portion that applies a moving magnetic field to the flow path and applies a thrust by the electromagnetic force to the conductive fluid in the flow path. There is a type pump.

  Mechanical pumps that require a seal portion have the disadvantage that conductive fluid leakage from the seal portion can occur. Most of the conductive fluids except mercury have a melting point of room temperature or higher, and when the molten metal has a high melting point, the seal bearing part has a limit in terms of heat resistance. On the other hand, the electromagnetic pump has no sliding parts such as a bearing with a seal that transmits a mechanical driving force to the impeller, and is therefore suitable for transporting molten metal at room temperature or higher.

  In particular, even in electromagnetic pumps, a magnetic field rotation that forms a magnetic field that rotates and moves in the circumferential direction in a cylindrical flow path, applies thrust to the conductive fluid in the flow path by electromagnetic induction, and conveys it. The electromagnetic pump has advantages such as a small installation space. As shown in FIG. 1, for example, the flow path of the electromagnetic pump of this type is such that the inflow side flow path 5 is connected to one end side of the partial cylindrical flow path 1 and the outflow side flow path 6 is connected to the other end side. Inductors 2, 2 ′ that form a magnetic field that continuously moves from the inflow side flow path 5 toward the outflow side flow path 6 in the circumferential direction of the flow path 1 in the partial cylindrical flow path 1. Is arranged. Since the flow path of such a magnetic field rotation type electromagnetic pump is such that the inflow side flow path 5 and the outflow side flow path 6 are connected to both ends of the partial cylindrical flow path 1, respectively. A flow path having a shape like that when contracted) is formed.

  The disadvantage of the magnetic field rotating electromagnetic pump having the Ω-shaped flow path is that the inflow side flow path 5 and the outflow side flow path 6 of the partial cylindrical flow path 1 interfere with each other and the outside of the partial cylindrical flow path 1. It is difficult to attach an inductor or a yoke for forming a magnetic path. For this reason, the magnetic resistance of the magnetic path of the magnetic field generated from the inductors 2, 2 ′ disposed inside the partial cylindrical flow path 1 increases with distance, and the inner circumferential side of the partial cylindrical flow path 1 is increased. There is a drawback that the magnetic field on the outer peripheral side becomes extremely weak compared to the magnetic field. An example of the distribution of magnetic flux density from the inner circumference side to the outer circumference side of the partial cylindrical flow path 1 is shown in FIG.

For example, as shown in FIG. 3A, when the electromagnetic force on the outer peripheral side becomes extremely weak compared to the inner peripheral side of the partial cylindrical flow path 1, the partial cylindrical shape is changed as shown in FIG. A large flow velocity distribution difference is generated between the inner peripheral side and the outer peripheral side of the flow path 1, and a back flow phenomenon of the conductive fluid sometimes occurs on the outer peripheral side of the flow path 1, and the flow rate-discharge pressure characteristics of the conductive fluid are not good. It becomes stable. FIG. 4A is an example of a normal flow rate-discharge pressure characteristic in which no back flow occurs because the electromagnetic force on the outer peripheral side of the partially cylindrical flow channel 1 is sufficient. On the other hand, in FIG. 4B, the electromagnetic force on the outer peripheral side of the partially cylindrical flow path 1 is insufficient, and therefore an unstable flow rate-discharge pressure in which a reverse flow is generated on the outer peripheral side of the flow path 1. It is an example of a characteristic. A range SR in which the flow rate-discharge pressure relationship is unstable as shown in FIG. 4B is called a so-called pulsation range.
JP 2007-74837 A JP 2004-304893 A JP 05-42357 A

  In view of the problems in the conventional magnetic field rotary electromagnetic pump having such a conventional Ω-shaped flow path, the present invention can achieve a stable flow rate by optimally setting the radial thickness and operating conditions of the partial cylindrical flow path. -It aims at providing the magnetic field rotation type electromagnetic pump which can acquire discharge pressure characteristic.

  In the present invention, in order to achieve the above object, the maximum value and the minimum value of the magnetic flux density distribution in the radial direction from the inner peripheral side to the outer peripheral side of the partially cylindrical flow path 1, that is, in the thickness direction of the flow path 1. The ratio is set to a certain value or less, and measures are taken to limit the difference between the flow velocity of the conductive fluid and the velocity of the rotating magnetic field in the flow path 1. This stabilizes the flow rate-discharge pressure characteristics.

  That is, in the magnetic field rotating electromagnetic pump according to the present invention, the inflow side flow path 5 is connected to one end side of the partial cylindrical flow path 1, and the outflow side flow path 6 is connected to the other end side. In the magnetic field rotating electromagnetic pump in which the inductors 2 and 2 ′ that form a magnetic field that rotates and moves from the inflow side flow channel 5 toward the outflow side flow channel 6 in the circumferential direction of the flow channel 1 are arranged. The thickness of the flow path 1 in the radial direction from the inner peripheral side to the outer peripheral side of the flow path 1 is set so that the magnetic flux density ratio ΦB / ΦA between the inner peripheral side and the outer peripheral side is 70% or more. .

  The inventors of the present invention analyzed and examined how much the magnetic flux is reduced on the outer peripheral side of the partially cylindrical flow path 1 where the magnetic flux density is generally the smallest, and the above-described reverse flow phenomenon occurs. As a result, generally, if the ratio ΦB / ΦA of the magnetic flux density ΦA on the inner peripheral side of the flow path 1 with the highest magnetic flux density and the magnetic flux density on the outer peripheral side of the flow path 1 with the smallest magnetic flux density is 70% or more, Focused on the fact that the reverse current phenomenon does not occur. The present invention has been made with this attention.

  Furthermore, even if the ratio ΦA / ΦB of the magnetic flux density between the inner peripheral side and the outer peripheral side of the partial cylindrical flow path 1 is 70% or less, the ratio ΦB / ΦA is set to be 55% or more, and It was noticed that if the magnetic field rotating electromagnetic pump is operated so that the slip value becomes 0.97 or less, the current reverse flow phenomenon does not occur. Here, the slip value s is s = (vs−vf) / vs (vs: the peripheral speed of the rotationally moving magnetic field in the flow path 1, vf: the peripheral speed of the conductive fluid in the flow path 1), and the flow path 1 is the ratio of the speed at which the magnetic flux of the rotationally moving magnetic field traverses the conductive fluid in 1.

  As described above, in the magnetic field rotating electromagnetic pump according to the present invention, the ratio of the magnetic flux density between the outer peripheral side of the flow path 1 having the largest magnetic flux density and the inner peripheral side of the flow path 1 having the smallest magnetic flux density is large. The magnetic flux density in the radial direction of the flow path 1 is leveled so that the resulting back flow phenomenon does not easily occur. For this reason, the flow rate-discharge pressure characteristic does not become unstable, and a stable magnetic field rotating electromagnetic pump can be operated.

In the present invention, in order to achieve the above object, the inflow side flow path 5 is connected to one end side of the partial cylindrical flow path 1, and the outflow side flow path 6 is connected to the other end side. 1 is a magnetic field rotating electromagnetic pump in which inductors 2 and 2 ′ that form a magnetic field that rotates and moves from an inflow side flow path 5 toward an outflow side flow path 6 in the circumferential direction of the flow path 1. The ratio ΦB / ΦA and the slip value s of the magnetic flux density ΦA on the inner peripheral side of the flow path 1 having the highest magnetic flux density and the magnetic flux density on the outer peripheral side of the flow path 1 having the smallest magnetic flux density were set appropriately.
Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  FIG. 1 is a conceptual perspective view showing an example of a magnetic field rotating electromagnetic pump having a Ω-shaped channel (a channel shaped as when a scale insect contracts) according to the present invention. This type of magnetic field rotating electromagnetic pump is used to flow a low melting point conductive fluid such as mercury or molten lead bismuth.

  The magnetic field rotation type electromagnetic pump has a partially cylindrical flow path 1, an inflow side flow path 5 connected to one end side thereof, and an outflow side flow path 6 connected to the other end side. Reference numeral 3 is an inlet of the inflow side channel 5, and reference numeral 4 is an outlet of the outflow side channel 6. The inflow port 3 and the outflow port 4 are connected to front and rear flow paths (not shown). The lengths of the inflow channel 5 and the outflow channel 6 can be changed as appropriate.

  One of the illustrated inductors 2, 2 ′ is disposed in the central portion of the partial cylindrical flow path 1. The inductor 2 has a cylindrical or columnar shape, and has a structure in which permanent magnets are alternately arranged at a predetermined interval in the circumferential direction so that the magnetic poles S and N poles on the outer peripheral side are alternately arranged. The inductor 2 is disposed in the hollow portion of the partial cylindrical flow path 1 and rotated by the motor 7 to rotate and move in the circumferential direction in the partial cylindrical flow path 1. Create a magnetic field.

  The other inductor 2 ′ also has a cylindrical or columnar shape, and has a structure in which electromagnets are arranged at a predetermined interval in the circumferential direction. An alternating magnetic field by three-phase alternating current or the like is applied to the electromagnet to form a moving magnetic field that rotates and moves in the circumferential direction in the partially cylindrical flow path 1. The frequency of the alternating magnetic field is varied by an inverter not shown.

  FIG. 5 is a diagram showing an electromagnetic force distribution generated by the moving magnetic field in the partially cylindrical flow path 1. The maximum magnetic flux density on the inner peripheral side of the flow path 1 is ΦA, and the minimum magnetic flux density on the outer peripheral side of the flow path 1 is ΦB. When the ratio ΦB / ΦA between the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB is 70% or more, no backflow occurs in the conductive fluid flowing through the partial cylindrical flow path 1.

  Further, even if the ratio ΦB / ΦA between the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB is 70% or less, if the ratio ΦB / ΦA between the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB is 55% or more, If the magnetic field rotation type electromagnetic pump is operated within a slip value s of 0.97 or less, no backflow occurs in the conductive fluid flowing through the partially cylindrical flow path 1.

Therefore, if the width of the flow path 1, that is, the thickness in the radial direction from the inner peripheral side to the outer peripheral side of the flow path 1 is set to any one of these conditions, the backflow of the conductive fluid flowing in the flow path 1 Does not occur, and the flow rate of the conductive fluid is stabilized. Incidentally, when the conductive fluid is Hg, the radial direction from the inner peripheral side to the outer peripheral side of the partial cylindrical flow path 1 when the ratio ΦB / ΦA of the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB is 55%. The thickness dimension corresponds to 15 mm.

  The conductive fluid flowing through the partially cylindrical flow path 1 includes hydraulic pressure loss and magnetic flux loss of the flow energy of the conductive fluid with respect to the wall of the flow path 1, and these losses are obtained from the output of the electromagnetic pump. The subtracted amount is the effective output that can be used as an electromagnetic pump. FIG. 6 shows the relationship between the theoretical output of this electromagnetic pump and the effective output that can be used as an electromagnetic pump obtained by subtracting the flow energy loss from this theoretical output.

  As already described, the slip value s is s = (vs−vf) / vs (vs: the peripheral speed of the rotating magnetic field in the flow path 1 and vf: the peripheral speed of the conductive fluid in the flow path 1). The ratio of the flow velocity of the conductive fluid in the flow path 1 and the speed at which the magnetic flux of the moving magnetic field crosses the conductive fluid. When the conductive fluid flows in the flow path 1 and the peripheral speed vf of the conductive fluid is the same as the peripheral speed vs of the rotating magnetic field, the slip value s is zero. At this time, the rotational movement magnetic field (rotational movement magnetic flux) in the flow path 1 and the peripheral speed of the conductive fluid are the same, and no induced current is generated in the conductive fluid, so the output is zero. On the other hand, when the peripheral speed vf of the conductive fluid in the flow path 1 is 0, such as when the valve is closed, the peripheral speed vs of the rotationally moving magnetic field in the flow path 1 is at that speed in the flow path 1. The slip value s across the conductive fluid is s = 1, the output is maximized, and the pressure gradient from the inlet to the outlet of the Ω-type channel increases.

If the ratio of the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB of the partial cylindrical flow path 1 is too large, the electromagnetic force becomes small in the vicinity of the portion showing the minimum magnetic flux density ΦB, and the conductivity flowing in the flow path 1 Back flow occurs in the fluid. When this backflow occurs, the output characteristics of the electromagnetic pump are not stable. In particular, backflow tends to occur in the range where the slip s is close to 1, that is, in the range where the output of the electromagnetic pump is close to the maximum. In the range where the slip s is close to 0, the output of the electromagnetic pump is small and the pressure gradient is small, so that the back flow hardly occurs.

  For this reason, it is necessary to determine the thickness in the radial direction from the inner peripheral side to the outer peripheral side of the partial cylindrical flow path 1 so that the ratio of the magnetic flux densities ΦB and ΦA is as high as possible. From such a viewpoint, the flow rate of the conductive fluid is analyzed by means such as the finite element method, and the ratio between the minimum magnetic flux density ΦB and the maximum magnetic flux density ΦA of the partial cylindrical flow path 1 and the presence or absence of the backflow phenomenon. The relationship was examined. As a result, it has been found that when the ratio ΦB / ΦA of the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB is 70% or more, no backflow occurs in the conductive fluid flowing through the partial cylindrical flow path 1. Further, even if the ratio ΦB / ΦA between the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB is 70% or less, the thickness of the flow path 1 is such that ΦB / ΦA is 55% or more, and the above slip value. It has also been found that if the magnetic field rotating electromagnetic pump is operated at s of 0.97 or less, no back flow occurs in the conductive fluid flowing through the partially cylindrical flow path 1.

  FIG. 7 shows the boundary between the range in which the backflow phenomenon occurs and the range in which the backflow phenomenon does not occur when the slip value s is 0.97, as a curve indicated by an arrow “backflow phenomenon range of s = 0.97”. If the magnetic field rotating electromagnetic pump is operated in a state where the slip value s is suppressed below the indicated curve shown in FIG. 7, no back flow phenomenon occurs.

  Originally, an electromagnetic pump applies an electric current to the conductive fluid from the outside or generates an induced current in the conductive fluid by electromagnetic induction, and propulsion by an electromagnetic force using the current in the conductive fluid and the magnetic field acting on the conductive fluid. Generate power. Therefore, the conductive fluid generates heat due to eddy current loss or the like generated in the conductive fluid. Further, if the wall of the channel 1 is a conductive material such as metal, the wall of the channel 1 also generates heat due to eddy current loss.

  Therefore, setting the slip value s near 1 and increasing the speed at which the magnetic flux of the rotationally moving magnetic field crosses the conductive fluid in the flow path 1 causes heat generation of the flow path 1 and the conductive fluid in the flow path. This is not preferable because it causes high temperatures. For this reason, in general, in the magnetic field rotation type electromagnetic pump, an emergency operation range is provided in the vicinity of the slip value s = 1. The hatched range in FIG. 7 is this emergency operation range.

  Since there is no problem even if the backflow phenomenon of the conductive fluid in the partial cylindrical flow path 1 occurs in this emergency operation range, the maximum magnetic flux density ΦA in the flow path 1 in which backflow does not occur outside this emergency operation range. And the minimum magnetic flux density ΦB, in other words, it is necessary to determine the thickness of the flow path 1 that satisfies this ratio. In FIG. 7, the optimum design is achieved by setting the thickness of the flow path 1 so as to bring the curve indicated by the hatched range and the “s = 0.97 reverse flow phenomenon range” arrow.

  According to the above-described flow analysis of the conductive fluid, the flow path when the slip value s below the line indicated by the arrow “s = 0.97 reverse flow phenomenon range” in FIG. 7, that is, s> 0.79. It was found that a reverse flow phenomenon occurred in the conductive fluid in 1. Therefore, when the ratio ΦB / Φ between the maximum magnetic flux density ΦA and the minimum magnetic flux density ΦB is set to 55% or more, an emergency as shown by hatching in FIG. 7 in the range between the slip value s = 0.97-1 The operating range will be determined.

  The present invention relates to a magnetic field rotary electromagnetic pump having an Ω-shaped flow path, and particularly to a magnetic field rotary electromagnetic pump used for flowing a low melting point conductive fluid such as mercury or molten lead bismuth. The present invention can be applied as a technique that can contribute to the stabilization of fluid flow characteristics.

It is a conceptual perspective view which shows one Example of the magnetic field rotation type electromagnetic pump which has the omega-shaped channel | path by this invention. It is a conceptual diagram which shows the example of the magnetic flux density distribution of the radial direction of the partial cylindrical flow path in the said magnetic field rotation type electromagnetic pump. It is the partial conceptual diagram of the flow path which shows the electromagnetic force distribution and flow velocity distribution of the radial direction of the said partial cylindrical flow path, respectively. It is a graph which shows the example of the relationship of the flow volume-discharge pressure of the state in which the flow of the electroconductive fluid of the said partial cylindrical flow path is normal, and the state in which a partial backflow state has arisen. It is the partial conceptual diagram of the flow path which shows the electromagnetic force distribution of the radial direction of the said partial cylindrical flow path. It is a graph which shows the example of the relationship between the theoretical output in the said magnetic field rotation type electromagnetic pump, and the effective output which can be utilized as an electromagnetic pump which deducted loss from this theoretical output. It is a graph which shows the example of the range of the range where a backflow phenomenon occurs when the slip value s is 0.97 in the magnetic field rotation type electromagnetic pump and the range where it does not occur, and the emergency operation range where overheating is likely to occur.

Explanation of symbols

1 Partially cylindrical flow path 2 Inductor 5 Inflow side flow path 6 Outflow side flow path

Claims (2)

An inflow side flow channel (5) is connected to one end side of the partial cylindrical flow channel (1), and an outflow side flow channel (6) is connected to the other end side of the partial cylindrical flow channel (1). Inductors (2) and (2 ') that form a magnetic field that rotates and moves from the inflow side flow path (5) toward the outflow side flow path (6) in the circumferential direction of the flow path (1). In the magnetic field rotation type electromagnetic pump, the thickness of the flow path (1) in the radial direction from the inner circumference side to the outer circumference side of the flow path (1) is the ratio of magnetic flux density ΦB / ΦA between the inner circumference side and the outer circumference side. A magnetic field rotating electromagnetic pump having a function of preventing backflow, characterized by having a function of preventing backflow in the pump by being set to be 70% or more. An inflow side flow channel (5) is connected to one end side of the partial cylindrical flow channel (1), and an outflow side flow channel (6) is connected to the other end side of the partial cylindrical flow channel (1). Inductors (2) and (2 ') that form a magnetic field that rotates and moves from the inflow side flow path (5) toward the outflow side flow path (6) in the circumferential direction of the flow path (1). In the conductive fluid induction type electromagnetic pump, the thickness of the flow path (1) in the radial direction from the inner circumference side to the outer circumference side of the flow path (1) is set to the ratio of the magnetic flux density ΦB / A magnetic field having a function of preventing backflow, characterized by having a function of preventing backflow in the pump by setting ΦA to be 55% or more and operating at a slip value s of 0.97 or less. Rotary electromagnetic pump.

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