JPH0476276A - Electromagnetic pump - Google Patents

Abstract

PURPOSE:To transmit heat generated in a stationary coil to the whole part of an electromagnetic pump efficiently and enable preheating evenly and rapidly by changing gas atmosphere in a casing upon preheating over inactive gas excellent in heat conductivity. CONSTITUTION:In a casing 9 a gas supplying nozzle 17 is arranged, and the fore-end thereof is extended in the vicinity of fluid inlet 7. The nozzle 17 is connected to a vacuum exhaust line 12, inactive gas supply line 13 and insulation gas supply line 14 respectively through solenoid valves 20 to 22. The inside of the casing 9 is made under gas atmosphere 11 to prevent discharge with a stationary coil 2 as well as oxidation. The gas atmosphere 11 is filled with insulation gas excellent in electric insulation upon operation, and under the condition an electromagnetic pump is immersed with fluid 10. During preheating operation, vacuum operation is carried out by the line 12 to make the vacuum gas atmosphere 11 in the casing 9, and thereafter inactive gas of high heat conductivity is supplied with the line 13.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention applies a traveling magnetic field to a conductive fluid from the outside to induce an induced current in the fluid, and the interaction between this induced current and the external magnetic field. This invention relates to a three-phase AC induction type electromagnetic pump that generates a pumping action.

(Prior art) In general, a three-phase AC induction type electromagnetic pump has three-phase AC windings distributed in the order of each phase in each direction of the flow of the electromagnetic pump, and when three-phase AC is caused to flow through these windings, , a traveling magnetic field is generated in the direction of the fluid flow. When this traveling magnetic field passes through a duct containing a conductive fluid, a voltage is induced in the fluid according to Fleming's right-hand rule, which causes an induced current to flow. This induced current and some components of the traveling magnetic field act to create an electromagnetic force, which acts as a pump by receiving force so that the fluid flows.

This electromagnetic force is the same as the torque in an induction motor and the thrust in a linear motor.

Three-phase AC induction electromagnetic pumps can be roughly divided into two types based on their structure: (1) flat linear electromagnetic pumps and (2) annular linear electromagnetic pumps.

Among these, the annual linear electromagnetic pump has an annular flow path cross section.
It is called "inear induction (abbreviation of I'ump)".

Electromagnetic pumps have become mainstream in recent years because of their highly reliable and safe duct structure.

Figure 2 shows the basic structure of ALIP. The structural features include the following.

(1) The duct through which the conductive fluid flows has a concentric double pipe structure with the outer duct 4 and the inner duct 5, and an annulus flow path 3 through which the fluid flows is formed between the two ducts 4 and 5.

(2) The stator has a plurality of laminated iron core blocks 1, each of which has slotted iron cores stacked in the circumferential direction, arranged outside the outer duct 4 in the circumferential direction to form a magnetic circuit for an alternating magnetic field. In this case, the laminated surface faces the duct and the slots are located inside, so that the entire core is radial.

A ring-shaped stator coil 2 is arranged within this slot. A large number of coils are arranged in the axial direction and wired so that the three-phase alternating current creates a traveling magnetic field.

(3) Inside the inner duct 5, a laminated inner core 6 for forming a magnetic circuit is housed.

(4) The fluid flows through the annulus channel 3 that enters the electromagnetic pump from the input lower, pressure is induced, and the fluid exits from the outlet 8.

(5) The stator coil 2 is cooled by gas circulated by an external fan.

In recent years, electromagnetic pumps have been made more compact and larger in capacity in order to eliminate restrictions on installation locations and improve the design of plants using electromagnetic pumps. It has become necessary to operate the device by immersing it in a fluid.

In order to satisfy the above requirements, instead of cooling the coil with forced gas as in the past, it is necessary to cool the surface of the coil without circulating cooling gas.

Doing this has many advantages:

(1) The space for circulating cooling gas is omitted, and the external dimensions can be reduced.

(2) No external device is required for circulating cooling gas.

(3) The immersion type has a great advantage because there is no need for piping to circulate cooling gas between the main body and the external device.

(4) In addition, if the jacket surface is cooled, if the machine has a certain large capacity, coils can be placed in the internal core, which was not possible with conventional machines, so the output of the electromagnetic pump will further increase. It can be made compact.

In the case of jacket surface cooling, it is necessary to transfer the heat loss generated in the coil from the coil to the core, and from the core to the duct or frame to release the heat into the fluid. Therefore, it is important to minimize the thermal resistance from the coil to the fluid, and for this purpose, it is important to ensure that these structures are in contact with each other during operation.

(Problems to be Solved by the Invention) However, in order to increase the output of the electromagnetic pump as much as possible, a large amount of current is passed through the coil.

For this reason, the temperature rise in the coil must be as small as possible. Also, since conductive fluids are generally used at high temperatures, electromagnetic pumps immersed in them must be operated at high temperatures. Become.

Electromagnetic pumps are assembled at room temperature and operated at various temperatures up to 600'C. Therefore, at any temperature, it is necessary to efficiently release the heat generated in the coil to the fluid without being subjected to stress due to differences in thermal expansion between the structures.

When trying to increase the pump capacity and make the pump more compact with such an electromagnetic pump, it is necessary to increase the current flowing through the stator coil as much as possible by efficiently dissipating the heat generated in the stator coil, which is the heat generating part, to the fluid. becomes important.

In conventional electromagnetic pumps, the heat generated by the coil is transferred to the outer duct 4 via the laminated core block 1, and from the outer duct 4 into the conductive liquid. Additionally, the inside of the casing is filled with nitrogen gas to prevent oxidation and discharge in the coil. However, this makes it difficult to uniformly raise the temperature of the electromagnetic pump because the temperature rise speed at the bottom of the casing is slow during preheating, and a large temperature difference occurs between the upper and lower external ducts.

The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide an electromagnetic pump that can be easily preheated without creating a large temperature difference within the electromagnetic pump during preheating. .

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, an electromagnetic pump according to the present invention has a double cylindrical pump that allows conductive fluid to flow through an annulus flow path formed between an outer duct and an inner duct. A duct, a plurality of laminated core blocks having slots arranged on the outer periphery of the double cylindrical duct, and creating a traveling magnetic field in the annulus channel arranged in the slots of the laminated core block and in which the conductive fluid is present. In an electromagnetic pump equipped with a large number of stator coils that flow a three-phase alternating current, the gas atmosphere inside the casing housing the laminated iron core block and stator coils is changed to an insulating gas with good electrical insulation during operation. It is characterized by being configured so that it can be switched to an inert gas with high thermal conductivity during preheating.

(Function) In the electromagnetic pump having the above configuration, by switching the gas atmosphere inside the casing to an inert gas with good thermal conductivity during preheating, the heat generated in the stator coil can be efficiently transferred to the electromagnetic pump. This makes it possible to spread the heat throughout the entire area, making it easy to preheat uniformly and rapidly.

(Example) Hereinafter, one embodiment of the present invention will be described based on FIG.

Note that the same reference numerals as in FIG. 2 will be used to describe parts that are the same as or correspond to the conventional configuration.

In FIG. 1, a plurality of laminated core blocks 1 are arranged in a casing 9 at approximately equal intervals in the circumferential direction, and inside this laminated core block 1, a large number of stator coils 2 are arranged in the axial direction. There is. Further, inside the laminated core block 1, an outer duct 4 and an inner duct 5 forming an annulus flow path 3 are arranged in a double cylindrical duct structure. An internal core 6 is inserted into the internal duct 5. The lower side of the annulus flow path 3 shown in FIG. 1 is a fluid lower part into which the conductive fluid flows, and the upper side thereof is a fluid lower part 8 through which the fluid flows out.

A gas injection nozzle 17 is disposed within the casing 9, and its tip extends in the axial direction of the casing 9 to the vicinity of the fluid entry lower part. This injection nozzle 17 is connected to a solenoid valve 20.
21 and 22 respectively to the vacuum evacuation line 12.
It is connected to an inert gas supply line 13 such as helium gas and an insulating gas supply line 14 such as nitrogen gas. The interior of the casing 9 is a gas atmosphere 11 to prevent oxidation and discharge in the stator coil 2. During operation, this gas atmosphere 11 is filled with an insulating gas having good electrical insulation properties, such as nitrogen gas, and the electromagnetic pump is immersed in the fluid 10 in this state.

Also, during preheating, the vacuum is evacuated by the vacuum exhaust line 12,
After the gas atmosphere 11 inside the casing 9 is evacuated, for example, helium gas is supplied as an inert gas with high thermal conductivity from the inert gas supply line 13 such as helium gas. Filled. The filling pressure of this helium gas is 2 to 4 kg/cnf
It was set as G. After preheating is completed, the inside of the casing 9 is evacuated again by the vacuum exhaust line 12, and then the insulating gas supply line 1
For example, nitrogen gas is supplied as an insulating gas having good electrical insulation from No. 4 to create a nitrogen gas atmosphere.

Furthermore, a gas purge line 16 is connected to the casing 9, and a gas discriminator 15 and a solenoid valve 23 are attached to the gas purge line 16 to determine whether the atmosphere is an inert gas atmosphere such as helium gas or an insulating gas atmosphere such as nitrogen gas. There is. The discrimination signal of the gas discriminator 15 is sent to the control device 18, and the control device 18 controls the solenoid valves 20, 21, 22 and 23.
It is designed to output open/close signals. Note that the relationship between the inner duct 5 and the inner core 6 is the same as that of the conventional structure, so a description thereof will be omitted.

Next, the operation of this embodiment will be explained.

Since a high voltage is applied to the electromagnetic pump during operation, an insulating gas with good electrical insulation, such as nitrogen gas, is filled to prevent stator coil 2 from discharging. Therefore, an inert gas having a better thermal conductivity than nitrogen gas, for example, helium gas, which has a thermal conductivity about 7 times better than nitrogen gas, is used. moreover,
By pressurizing the introduced helium gas to several atmospheres, the heat generated in the stator coil 2 is transmitted to the entire inside of the casing 9 via the helium gas, making it easy to uniformly preheat the inside of the electromagnetic pump.

In addition, a helium gas (inert gas) atmosphere or nitrogen gas (
The gas discriminator 15 monitors whether the atmosphere is an insulating gas (insulating gas) atmosphere, and even if a voltage higher than the preheating setting voltage is applied to the electromagnetic pump in a helium gas atmosphere, the control device 18 issues an interlock signal and the electromagnetic pump control panel 19 is made so that the voltage does not exceed the set voltage. Furthermore, by switching the mode of the control device 18 from preheating to operation, the solenoid valve 20.21 is automatically closed, and by opening the solenoid valve 22.23, the inside of the casing 9 is purged with nitrogen gas as an insulating gas. starts, and when the gas discriminator 15 confirms that the gas has been replaced with nitrogen gas, the solenoid valves 22 and 23
is closed, the gas purge is completed, and the interlock of the control device 18 is released. In this way, application of high voltage in an atmosphere of helium gas as an inert gas due to malfunction can be prevented and switching from preheating to operation can be easily prevented.

As described above, according to this embodiment, since the pressure of the inert gas such as helium gas in the casing 9 is increased to several atmospheres for preheating, it becomes easy to uniformly preheat the inside of the electromagnetic pump.

〔Effect of the invention〕

As explained above, according to the present invention, the heat generated in the stator coil is efficiently transmitted throughout the casing using an inert gas with high thermal conductivity, and the electromagnetic pump can be preheated easily and rapidly. This has the effect that the preheating time can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional system diagram showing an embodiment of an electromagnetic pump according to the present invention, and FIG. 2 is a partially cutaway perspective view of a conventional electromagnetic pump. 1... Laminated iron core block, 2... Stator coil, 3
...annulus flow path, 4...outer duct, 5...
Inner duct, 6...Inner core, 9...Casing,
11... Inert gas atmosphere, 13... Helium gas supply line, 14... Nitrogen gas supply line, 15...
- Gas discriminator, 18...control device. young prisoner

Claims (1)

[Claims] A double cylindrical duct that allows conductive fluid to flow through an annulus flow path formed between an outer duct and an inner duct, a plurality of laminated iron core blocks having slots arranged on the outer periphery of the double cylindrical duct, and this laminated core block. An electromagnetic pump comprising a large number of stator coils that are arranged in slots of an iron core block and that flow a three-phase alternating current to create a traveling magnetic field in the annulus flow path in which the conductive fluid exists, the laminated iron core block and An electromagnetic pump characterized in that the gas atmosphere inside a casing housing a stator coil can be switched to an insulating gas with good electrical insulation during operation and an inert gas with high thermal conductivity during preheating.