JPH08330060A - Electromagnetic induction heating device - Google Patents

Abstract

PURPOSE: To prevent the breakage of a pipe and uniformly heat a fluid. CONSTITUTION: This electromagnetic induction heating device is provided with a nonmagnetic pipe 6 where a fluid 14 flows in or out, a coil 7 wound on the pipe 6, a heating element 8 stored in the pipe 6 and heated by the coil 7 via electromagnetic induction, and a holding member 30 holding the heating element 8 to face the coil 7 from the inflow side A of the fluid 14. A circular gap Rs absorbing the thermal expansion difference in the radial direction between the heater element 8 and the pipe 6 is formed between the heater element 8 and the pipe 6. A gap Vs absorbing the thermal expansion in the axial direction of the heater element 8 is formed between the heater element 8 and the pipe 6 on the outflow side B of the pipe 6, and a stopper 35 coupled with the heater element 8 by the thermal expansion in the axial direction of the heater element 8 and capable of blocking the circular gap Rs from the outflow side B is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction heating apparatus for heating a heating element immersed in a fluid such as liquid or gas by electromagnetic induction heating and heating the fluid by direct heat transfer.

[0002]

2. Description of the Related Art For example, a distillation column is indispensable in a reaction / separation process in a chemical plant. This distillation column is
It is a device that separates the mixed liquids by the difference in the boiling points of the liquids that make up the distillate. A device for heating the distillate is attached to this distillation column. As the heating device, for example, an indirect heating device such as a sheath heater system is adopted. In this sheath heater system, a power source is turned on to the sheath heater to heat the heat transfer oil, and heat is exchanged between the heat transfer oil and the distillate with a heat exchanger.

In the sheathed heater system by indirect heating, since the heat transfer oil is first heated by the sheathed heater, the rise time is long and the heating device tends to be bulky. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 3-98286, a column or case through which a fluid passes is made of an insulator, and a heating element in which the fluid is stored is heated by electromagnetic induction. It has been proposed to incorporate a direct heating electromagnetic induction heating device into the pipeline. According to the electromagnetic induction heating device based on the direct heating, the heat transfer efficiency from the heating element to the fluid can be improved up to about 90% by increasing the heat transfer area of the heating element in which the fluid is immersed. Can be shortened.

[0004]

However, since the electromagnetic induction heating device proposed in Japanese Patent Laid-Open No. 3-98286 is small in size and capable of local heating, the thermal expansion of the heating element of the device and the column or the case. Due to the difference, that is, the thermal expansion of the heating element housed in the column or case becomes large, so that the heating element thermally expands during heating and exerts a stress that pushes the column or case to damage the column or case. There was a problem of doing. In this case, it is conceivable to form a gap that absorbs the difference in thermal expansion between the column or case and the heating element, but some fluid may pass through this gap without flowing into the heating element. Therefore, it is difficult to achieve uniform heating of the fluid by the heating element.

The present invention has been made to solve this problem, and an object of the present invention is to provide an electromagnetic induction heating device capable of preventing breakage of a pipe and achieving uniform heating of a fluid.

[0006]

In order to solve the above problems, in an electromagnetic induction heating apparatus of the present invention, a pipe made of a non-magnetic material into and out of which a fluid flows, a coil wound around the pipe, and the inside of the pipe. And a holding member that holds the heating element so as to face the coil from the inflow side of the fluid, and is disposed between the heating element and the pipe. An annular gap that absorbs a difference in radial thermal expansion between the heating element and the pipe is formed in the heating element, and a gap that absorbs thermal expansion in the axial direction of the heating element is provided on the outflow side of the pipe. And a stopper which is formed between the heat generating element and the heat generating element and is engaged with the heat generating element by the thermal expansion of the heat generating element in the axial direction so that the annular gap can be closed from the outflow side.

[0007]

As described above, according to the electromagnetic induction heating apparatus of the present invention, when the fluid is flowed from the inflow side to the outflow side and the fluid is heated through the pipe and the heating element by the electromagnetic induction by the coil, the pipe and the heating element are separated. Although there is a difference in thermal expansion between the pipe and the heating element, an annular gap larger than the difference in thermal expansion is formed between the pipe and the heating element. The action of stress caused by abutting against the pipe and pushing is prevented, and the heat generating element also thermally expands in the direction in which the fluid flows, but this thermal expansion can be absorbed by the gap formed between the heating element and the stopper. .

Further, the fluid flowing into the inflow side flows into the heating element and is heated and flows to the outflow side. At the same time, a part of the fluid flows into the annular gap directly from the inflow side or from the heating element. Through the annular gap and try to flow to the outflow side, but the heating element heated by electromagnetic induction by the coil thermally expands and engages the stopper, blocking the outflow side of the annular gap and allowing the fluid to flow directly. To prevent it from flowing to the outflow side,
A pressure is generated in the annular gap by the flow of the fluid from the inflow side, and the fluid flowing into the annular gap can be caused to flow into the heat generating body by this pressure.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electromagnetic induction heating apparatus which is an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view of the electromagnetic induction heating device in this embodiment, and FIG. 2 is a structural diagram of a heating element used in the electromagnetic induction heating device in this embodiment.

In FIG. 1, the electromagnetic induction heating device 1 has flanges 2 and 3, short pipes 4 and 5, a pipe 6, a coil 7, a heating element 8 and pipes 9 and 10 as main parts. The holding member 30 and the ring-shaped stopper 35 are provided, and the fluid 14 flows from the lower side to the upper side in FIG. 1 and is installed in a pipeline 104 of a chemical plant or the like. The power unit 11 is connected in common to the coil 7 of each device 1 or the coils 7 of the plurality of devices 1, the power unit 11 is connected to the control unit 12, and the control unit 12 is connected to the temperature sensor 13. Constitutes a heating system.

The materials of the flanges 2 and 3 and the short tubes 4 and 5 are
It is necessary to have corrosion resistance to various fluids 14 handled in a chemical plant, and austenitic stainless steel such as non-magnetic SUS316 is used so that it is not easily affected by the magnetic flux formed by the coil 7. Although this austenitic stainless steel is generally considered to be non-magnetic, it is not completely non-magnetic and is slightly affected by magnetic flux. The flange 2 and the short pipe 4 are formed into a flange with a short pipe by welding or the like, and the flange 3 and the short pipe 5 are also formed into a flange with a short pipe by welding or the like. Each of the flanges 3 and 4 is bolted to the pipeline 104. The flanges with short pipes become the inflow side A or the outflow side B of the fluid 14 into the device 1 by joining with screws or the like. Further, in particular, the same SUS316 socket 4a is fixed to the short pipe 4 located on the outflow side B of the fluid 14 by welding or the like, and the fitting 13a for attaching the temperature sensor 13 can be screwed in. Then, by screwing the holding metal fitting 13b into the fitting 13a, the tip of the temperature sensor 13 can be fixed in a state of being positioned near the center of the short tube 4. The position of this socket 4a depends on the temperature sensor 13 such as the fitting 13a.
It is preferable that the parts are provided close to the flange 2 to the extent that they do not interfere with the flange 2. The flanges 2 and 3
The short pipes 4 and 5 are not limited to those attached by welding,
It may be integrally formed as a flange with a short pipe. The sensor attached to the short pipe 4 is not limited to the temperature sensor and may be another sensor such as a pressure sensor.

The pipe 6 is made of cement, glass, ceramics and other inorganic non-metallic materials such as ceramics, traditional ceramics such as nikko ware, ceramics containing fluorine (for example, the content ratio of ceramics: 95%, Fluorine: 5%) In addition to that, it is made of ceramics such as fine ceramics obtained by sintering alumina or silicon nitride. It is a non-magnetic material and has excellent heat resistance and corrosion resistance. Things are selected. The heating element 8 is housed in the pipe 6, and the coil 7 is wound around the pipe 6 at a position facing the heating element 8. Note that the pipe 6 may be a pipe having two or more splices due to manufacturing restrictions.

The both ends of the pipe 6 and the short pipes 4 and 5 are not directly joined but are joined via the pipes 9 and 10. A high-strength heat-resistant alloy such as Fe-Ni-Co alloy is selected as the material of the tubes 9 and 10. Further, generally, the coefficient of thermal expansion of ceramics is small, and the coefficient of thermal expansion of austenitic stainless steel is large. Therefore, when ceramic is used for the pipe 6 and austenitic stainless steel is used for the short pipes 4 and 5, a large thermal stress occurs when the pipe 6 and the short pipes 4 and 5 are directly joined. Therefore, the thermal expansion coefficient of the pipes 9 and 10 interposed between the pipe 6 and the short pipes 4 and 5 is selected to be intermediate between the thermal expansion coefficients of ceramic and austenitic stainless steel. Also, the short pipe 4,
Between the pipe 5 and the pipe 9,10 and the pipe 9,10 and the pipe 6
The gap between the two is performed by fusion using silver solder or nickel solder.

Although the pipe 10 is straight, the pipe 9 is corrugated and is expandable and contractable in the axial direction. When the fluid 14 is heated via the heating element 8 in the device 1,
Due to the thermal expansion, not only the device 1 but also the pipeline 104 extends in the axial direction. Therefore, when the device 1 is incorporated into the pipeline 104 by flange joining, unexpected thermal stress may be generated in the weakest part of the device 1, so that a corrugated shape for escape of thermal expansion is provided in the device 1. A tube 9 was provided. The corrugated pipe 9 can also absorb manufacturing errors in the axial direction and the axial center direction of the pipeline 104 and the apparatus 1. Further, since this corrugated tube 9 is also bendable, it is possible to absorb the deviation of the parallelism between the flanges 2 and 3.

As the coil 7, a coil having as little copper loss as possible is used. A coiled litz wire or a copper tube such as a round tube, a semi-circular tube or an elliptic tube is used. The power unit 11 connected to the coil 7 is, for example, 200V, 50/60
AC / power source 11a of
It is composed of a DC rectification unit, a non-smoothing filter, and a high power factor high frequency inverter unit.
It is converted into the alternating power source 11b which is oscillated at high frequency within the waveform of 0 Hz. The control unit 12 includes a temperature adjustment unit and a phase shift control unit, and the phase shift control unit changes the phase difference to change the phase difference.
1 for adjusting the output voltage from the temperature control unit 1, and the temperature adjustment unit changes the phase difference of the phase shift control unit according to the output from the temperature sensor 13. The power unit 11 and the controller 12 can output an output voltage of 0 to 100% and a high frequency of at least 15 to 150 KHz to the coil 7.

It is preferable that the heating element 8 has a magnetic permeability that allows electric power to easily enter, heat exchange with the fluid 14 easily, and corrosion resistance with respect to the fluid 14. As such a material, martensite type stainless steel such as SUS447J1 is used. Further, the detailed structure of the heating element 8 will be described with reference to FIG. FIG. 2A shows a heating element 8.
2B is a perspective view showing the structure of the heating element 8. FIG.

In the heating element 8, flat plate-shaped first sheet materials 21 and corrugated second sheet materials 22 are alternately laminated so that the first sheet materials 21 are located at both ends of the side surface, and the whole is circular. It is formed in a columnar shape. The wave crests (or troughs) 23 of the second sheet material 22 are arranged so as to be inclined by an angle α with respect to the central axis 24, and the wave crests of the adjacent second sheet material 22 with the first sheet material 21 interposed therebetween ( (Or valley) 23 is arranged so as to intersect. Then, the adjacent second sheet material 22
At the intersection 25 of the wave mountain (or valley) 23 in
The first sheet material 21 and the second sheet material 22 are welded by spot welding so that they can be electrically conducted. Also, the second
The surface of the sheet material 22 is provided with holes 26 for causing turbulent flow of the fluid 14. Instead of or in addition to the holes 26, it is also effective to apply a satin finish to the first sheet material 21 and / or the second sheet material 22 to make the surface rough. In short, the first sheet material 21 and the second sheet material 22 are arranged substantially parallel to the diametrical direction D passing through the central axis 24 of the heating element 8, and are electrically parallel to the diametrical direction D (peripheral portion). Is the easiest to flow.
Then, the skin effect (a state in which only the outer peripheral portion of the heating element 8 is heated) that appears in electromagnetic induction is broken, and the central portion of the heating element 8 is also heated. The heating element of the type in which the central portion of the heating element 8 is heated is not limited to the laminated structure of the sheet materials 21 and 22, and may be a heating element formed by assembling a large number of small diameter tubes. In this case, the surface of each of the small-diameter pipes is heated, and a heating element capable of heating substantially uniformly as a whole is obtained.

Further, the heating element 8 at the beginning of molding has a diameter D so as to form an annular gap Rs between the outer peripheral surface thereof and the inner peripheral surface of the pipe 6, so that the axial center and the heat generation inside the pipe 6 are generated. Body 8
It is loosely fitted so that the shaft centers of the two are aligned, inserted into the pipe 6, and held by the holding member 30. The diameter D of the heating element 8 is not less than the difference in thermal expansion between the amount of thermal expansion of the pipe 6 in the radial direction and the amount of thermal expansion of the heating element 8 in the radial direction when the fluid 14 is heated by the device 1. The annular gap Rs is determined to be provided between the heating element 8 and the pipe 6. In addition, the holding member 30 is arranged so that the metal bar 31 which is welded to the short pipe 5 on the inflow side A by welding or the like and extends in the radial direction, and the tip of the metal bar 31 coincides with the axial center of the heating element 8. It is composed of a fixed non-magnetic holding rod 32. And
The holding rod 32 is made of ceramic or the like that is excellent in non-magnetism, heat resistance, and corrosion resistance and extends from the inflow side A to the outflow side B. The tip of the holding rod 32 positions the heating element 8 at a position relative to the coil 7. And hold. Reference numeral 35 denotes a ring-shaped stopper, which is made of non-magnetic, heat-resistant and corrosion-resistant ceramic or the like, and is fitted into the pipe 6 from the outflow side B of the fluid 14 and between the heat generating body 8. The heating element 8
Vs that is the same as or slightly less than the amount of thermal expansion in the axial direction of
Has been fixed. In addition, the ring-shaped stopper 35
Is located on the heating element 8 across the annular gap Rs from the outflow side B in the radial direction, and is engaged with the heating element 8 due to the thermal expansion of the heating element 8 and the annular gap Rs from the outflow side B. Block.

When the fluid 14 flows from the inflow side A to the outflow side B of the apparatus 1 and the fluid 14 is heated via the pipe 6 and the heating element 8 by electromagnetic induction by the coil 7, the pipe 6 and the heating element 8 are separated from each other. Although there is a difference in the thermal expansion in the radial direction, an annular gap Rs larger than the thermal expansion difference is formed between the pipe 6 and the heating element 8. Therefore, the thermal expansion difference is absorbed while narrowing the annular gap Rs. As a result, the action of stress due to the heating element 8 coming into contact with and pushing the pipe 6 is prevented, and the heating element 8 also thermally expands in the axial direction. It is absorbed by thermally expanding the gap Vs formed in the.

At this time, from the pipeline 104 to the device 1
The fluid 14 that has flowed into the inflow side A flows into the heating element 8 and is heated and flows to the inflow side B, and a part of the fluid 14 flows directly from the inflow side A or from the heating element 8. Although it tries to flow into the gap Rs, pass through the annular gap Rs, and flow toward the inflow side B, the heat generating body 8 engages with the ring-shaped stopper 35 by thermal expansion in the axial direction, so that the outflow side B of the annular gap Rs. Is blocked to prevent the fluid 14 from directly flowing to the outflow side B, so that the flow of the fluid 14 from the inflow side A causes a pressure to be pushed to the outflow side B in the annular gap Rs.
The fluid 14 flowing into the annular gap Rs can be caused to flow into the heating element 8 by this pressure.

As a result, even if the heating element 8 is heated by electromagnetic induction by the coil 7, damage to the pipe 6 due to thermal expansion of the heating element 8 can be prevented and the thermal expansion of the heating element 8 can be absorbed. Even if the annular gap Rs is formed, the heating element 8 thermally expands and engages with the ring-shaped stopper 35 to close the annular gap Rs from the outflow side B, and the fluid 14 flowing out into the annular gap Rs is heated. Since the fluid 14 can be made to flow into the heating element 8, the fluid 14 can be uniformly heated by the heating element 8.

In the electromagnetic induction heating apparatus of this embodiment, the heating element 8 is held by the metal bar 31 and the holding rod 32 from the inflow side A of the fluid 14, but the structure is not limited to this. Alternatively, as shown in FIG. 3, the heating element 8 may be held by providing a plurality of protrusions 40 projecting from the pipe 6 in the circumferential direction thereof, either integrally or separately.

[0023]

As described above, according to the electromagnetic induction heating apparatus for a pipeline of the present invention, when the fluid is caused to flow from the inflow side to the outflow side and the fluid is heated through the pipe and the heating element by the electromagnetic induction by the coil, Although there is a difference in the thermal expansion in the radial direction between the pipe and the heating element, an annular gap larger than the difference in thermal expansion is formed between the pipe and the heating element. By absorbing, the effect of stress caused by the heating element coming into contact with and pushing the pipe is prevented, and
The heating element also thermally expands in the axial direction, but this thermal expansion is absorbed by thermally expanding the gap formed with the stopper, and the pipe is not affected by the thermal expansion of the heating element. Therefore, the pipe is not damaged.

The fluid flowing into the inflow side flows into the heating element and is heated and flows to the outflow side, and a part of the fluid flows into the annular gap directly from the inflow side or from the heating element. Through the annular gap and try to flow to the outflow side, but the heating element heated by electromagnetic induction by the coil thermally expands and engages the stopper, blocking the outflow side of the annular gap and allowing the fluid to flow directly. Since it is possible to prevent the fluid that has flowed into the annular gap from flowing into the heat generating body by flowing into the heat generating body, it is possible to allow all the fluid from the inflow side to pass through the heat generating body and to uniformly heat the fluid by the heat generating body. Can be achieved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electromagnetic induction heating apparatus according to an embodiment of the present invention.

2A and 2B are structural views of a heating element used in an electromagnetic induction heating apparatus according to an embodiment of the present invention, in which FIG. 2A is a top view showing the structure of the heating element, and FIG. It is a perspective view.

FIG. 3 is an enlarged view of a main part showing a modified example of the electromagnetic induction heating apparatus in the embodiment of the present invention.

[Explanation of symbols]

 1 Electromagnetic Induction Heating Device 6 Pipe 7 Coil 8 Heating Element 30 Holding Member 35 Ring Stopper (Stopper) Rs Annular Gap Vs Gap

Claims (1)

[Claims] 1. A pipe made of a non-magnetic material through which a fluid flows in and out, a coil wound around the pipe, a heating element housed in the pipe and heated by electromagnetic induction by the coil, and the heating element. A holding member that holds the coil so as to face the coil from the inflow side of the fluid, and an annular shape that absorbs a difference in radial expansion between the heating element and the pipe between the heating element and the pipe. A gap is formed, a gap for absorbing thermal expansion in the axial direction of the heating element is formed on the outflow side of the pipe between the heating element and the heat generation due to the thermal expansion in the axial direction of the heating element. An electromagnetic induction heating device comprising a stopper arranged to engage with a body so as to close the annular gap from the outflow side.