CN111556600A - Sleeve type transformer oil heating device and method based on electromagnetic induction heating principle - Google Patents
Sleeve type transformer oil heating device and method based on electromagnetic induction heating principle Download PDFInfo
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- CN111556600A CN111556600A CN202010569774.1A CN202010569774A CN111556600A CN 111556600 A CN111556600 A CN 111556600A CN 202010569774 A CN202010569774 A CN 202010569774A CN 111556600 A CN111556600 A CN 111556600A
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 96
- 230000005674 electromagnetic induction Effects 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000003921 oil Substances 0.000 claims description 121
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 230000008569 process Effects 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 7
- 230000006698 induction Effects 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000007769 metal material Substances 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 3
- 230000002500 effect on skin Effects 0.000 claims description 3
- 239000012208 gear oil Substances 0.000 claims description 3
- 238000003754 machining Methods 0.000 claims description 3
- 229910052755 nonmetal Inorganic materials 0.000 claims description 3
- 230000005855 radiation Effects 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 238000001035 drying Methods 0.000 description 12
- 229910000831 Steel Inorganic materials 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/02—Induction heating
- H05B6/06—Control, e.g. of temperature, of power
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/08—Cooling; Ventilating
- H01F27/10—Liquid cooling
- H01F27/12—Oil cooling
- H01F27/14—Expansion chambers; Oil conservators; Gas cushions; Arrangements for purifying, drying, or filling
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/02—Induction heating
- H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- General Induction Heating (AREA)
Abstract
The invention discloses a bushing type transformer oil heating device and method based on an electromagnetic induction heating principle.
Description
Technical Field
The invention relates to the technical field of transformer oil heating, in particular to a sleeve type transformer oil heating device and method based on an electromagnetic induction heating principle.
Background
Necessity of heating cycle of transformer oil: the water seepage of the transformer can be caused in the processes of transportation, installation and maintenance of the transformer and in a humid air environment, so that the insulativity of the transformer is reduced, and the breakdown voltage of the transformer is reduced. Therefore, before the transformer is put into use, the insulation of the transformer needs to be measured, and when the insulation of the transformer is judged to be not in accordance with the use standard, the transformer oil needs to be subjected to heating cycle drying treatment under vacuum conditions, the purpose is to heat the transformer body through the heating cycle of the transformer oil, so that the temperature in the transformer body is increased along with the heating cycle of the transformer oil, moisture existing in the transformer body and insulating substances is evaporated and dissolved in the transformer oil, the moisture is taken out of the transformer along with the circulation of the transformer oil and is separated from the transformer oil by other parts of a transformer oil heating cycle device, and during the circulation, the moisture in the transformer is gradually reduced, and the insulation of the transformer is recovered to a usable range.
The electromagnetic induction heating technology is characterized in that an alternating induction magnetic field generated by alternating current in a circuit passing through a coil is utilized, eddy current (induction current) can be generated when magnetic lines of the alternating induction magnetic field pass through the interior of a heated metal part, and the metal resistance of an eddy current loop is very small, so that the eddy current has very high current intensity and can generate very large Joule heat to heat the metal part.
Most of the research at present focuses on proposing a new drying method for transformers, however, the most important drying method for transformers at present is a hot oil circulation drying method, which has the disadvantages of low heating efficiency, poor drying effect of transformers using the drying method under extreme environments, and low energy utilization rate. There are also some researchers who have studied hot oil circulation drying methods related to electromagnetic induction heating, such as iron loss drying. Although the iron loss drying method utilizes the conservator of the transformer as a device heated by electromagnetic induction, the heating efficiency is low, the temperature uniformity of the transformer oil in the conservator is poor, and the oil is easy to deteriorate. The existing device and method for heating transformer oil by electromagnetic induction do not consider the heating uniformity of electromagnetic induction heating and the convection heat transfer strength of the transformer oil and the electromagnetic induction heating device, and the electromagnetic induction heating device is not designed from the angle of enhancing the flowing heat transfer characteristic of the transformer oil in the electromagnetic induction heating process.
The auxiliary heating device for the transformer oil based on electromagnetic induction and the control method (application number 201911046241.9) and the auxiliary heating device for the transformer oil based on the electromagnetic induction (application number 201621092915.0) provided by the national grid Ningxia electric power company overhaul company mainly utilize an electromagnetic induction coil to be wound on the surface of a steel oil pipe, utilize alternating current in a circuit to heat the steel oil pipe, and finally heat the transformer oil in the oil pipe. The patent provides a hot oil circulation drying loop combined with an oil filter device, but the heating uniformity of electromagnetic induction heating is not considered, the temperature of a steel oil pipe rises in the electromagnetic induction heating process, the steel oil pipe is always used for heating transformer oil on one side in the pipe, the temperature of the transformer oil near a heating wall surface is greatly different from that of the transformer oil in a flowing central area, the temperature uniformity is poor, meanwhile, the convection heat exchange effect of the transformer oil and the steel oil pipe is not considered from the perspective of heat transfer enhancement, and the heating performance of the steel oil pipe also has a space for improvement.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention aims to provide a bushing type transformer oil heating device and method based on an electromagnetic induction heating principle, wherein the bushing type transformer oil heating device can uniformly heat transformer oil flowing inside the heating device in the application of electromagnetic induction heating of the transformer oil, improve the temperature uniformity of the transformer oil in the heating process, improve the limit of maximum electromagnetic induction heating power under the condition that the heating temperature is lower than the deterioration temperature of the transformer oil, reduce the heating time of the transformer oil in the process of drying the transformer oil by hot oil circulation, and save the time cost.
In order to achieve the purpose, the invention adopts the following technical scheme:
a bushing type transformer oil heating device based on an electromagnetic induction heating principle comprises an outer pipe 1 and an inner pipe 2 which are of bushing type structures, wherein the inner pipe 2 is coaxially fixed on the inner wall surface of the outer pipe 1 through an insulating support 6, and an outer pipe electromagnetic induction coil 3 and an inner pipe electromagnetic induction coil 4 are respectively wound on the outer wall surfaces of the outer pipe 1 and the inner pipe 2; grooves are formed in the outer wall surface of the inner pipe 2 in a plurality of positions along the axial direction in an up-and-down mode and are used for installing an upper cover plate 7 and a lower cover plate 8 which are bent in a semicircular mode and provided with fins on the peripheries respectively, the upper cover plate 7 and the lower cover plate 8 form an integral columnar shape to wrap the inner pipe electromagnetic induction coil 4, the inner pipe electromagnetic induction coil 4 is isolated from transformer oil, and iron loss heat generated by the inner pipe 2 under the action of electromagnetic induction is transferred to the fins of the upper cover plate 7 and the lower cover plate 8 to heat the transformer oil between the outer pipe 1 and the inner pipe 2; according to the requirement of electromagnetic induction heating, different alternating currents and voltages are connected to realize the alternating change of the magnetic field in the sleeve structure, and joule heat is generated to increase the temperature of the outer pipe 1 and the inner pipe 2 of the sleeve structure so as to heat the transformer oil.
The inner wall surface of the inner pipe 2 is provided with a thread groove to enlarge the contact area between the inner wall surface of the inner pipe and the transformer oil flowing in the inner pipe, break the flowing boundary layer of the transformer oil, inhibit the growth of the boundary layer and improve the convective heat transfer intensity in the pipe.
The space between the outer wall surface of the inner tube 2 and the upper cover plate 7 and the lower cover plate 8, which is wound with the electromagnetic induction coil 4, is filled with a metal or non-metal material with high heat conductivity so as to reduce natural convection of air in the space and reduce thermal resistance of the outer wall surface of the inner tube 2 for transferring heat to the upper cover plate 7 and the lower cover plate 8.
The shape and structural size parameters of the upper cover plate 7 and the lower cover plate 8 are optimized, the convection heat transfer coefficient between the upper cover plate 7 and the transformer oil and between the lower cover plate 8 and the transformer oil are further improved, and the convection heat transfer is strengthened.
The contact surfaces of the outer wall surface of the inner tube 2 and the upper cover plate 7 and the lower cover plate 8 are coated with thermal interface materials, so that the contact thermal resistance caused by poor contact and machining precision is reduced, and the thermal resistance in the heat conduction process is reduced.
The upper cover plate 7 and the lower cover plate 8 are made of metal materials with high heat conductivity, and an inner lead hole 10 is drilled in the upper cover plate 7 to lead out the inner pipe electromagnetic induction coil 4; outer tube lead holes 9 are drilled in the outer wall surface of the outer tube 1, the inner tube electromagnetic induction coil 4 is led out to the external environment, and sealing parts 5 are installed at the positions of the outer tube lead holes 9 to prevent transformer oil from leaking from the outer tube lead holes 9.
The outer pipe 1 and the inner pipe 2 are made of low-resistance low-carbon steel materials.
The method for heating the transformer oil by the bushing type transformer oil heating device based on the electromagnetic induction heating principle is characterized by comprising the following steps of: the method comprises the following steps:
(1) alternating current and voltage are introduced into the outer pipe electromagnetic induction coil 3 and the inner pipe electromagnetic induction coil 4, an alternating magnetic field is generated inside the induction coils due to self-induction of the outer pipe electromagnetic induction coil 3 and the inner pipe electromagnetic induction coil 4, the outer pipe 1 and the inner pipe 2 generate eddy current under the action of the alternating magnetic field, current density is mainly concentrated on the outer wall surfaces of the outer pipe 1 and the inner pipe 2 due to skin effect, joule heat is generated by the outer pipe 1 and the inner pipe 2, and the temperature of the outer pipe 1 and the temperature of the inner pipe 2 are increased;
(2) the temperature of the inner tube 2 rises, heat is transferred to the transformer oil flowing in the tube in a convection heat exchange mode, and the thread structure on the inner wall surface of the inner tube 2 enhances the heat exchange in the tube; the inner pipe 2 transmits a part of heat to the upper cover plate 7 and the lower cover plate 8 in a heat conduction mode, the temperature of the upper cover plate 7 and the lower cover plate 8 is raised, and the heat is transmitted to the transformer oil flowing between the inner pipe 2 and the outer pipe 1 in a convection heat exchange mode;
(3) the temperature of the outer pipe 1 rises, most of heat is transferred to the transformer oil flowing between the outer pipe 1 and the inner pipe 2 in a convection heat exchange mode, and a small part of heat is transferred to the surrounding environment in a natural convection and heat radiation mode of the outer wall surface of the outer pipe 1;
(4) the transformer oil flows in from the inlet of the heating device, and after being heated, the transformer oil flowing in the inner tube 2 is mixed with the transformer oil flowing between the outer tube 1 and the inner tube 2 at the outlet;
(5) the sleeve type transformer oil heating device is connected with the gear oil pump and the oil tank to form a circulating heating system, and the circulating heating of the transformer oil is completed.
Compared with the prior art, the invention has the following advantages:
1) according to the invention, a sleeve type structure is adopted, electromagnetic induction coils are wound on the outer wall surfaces of the outer pipe 1 and the inner pipe 2, under the action of alternating current and voltage, the outer pipe 1 and the inner pipe 2 generate joule heat to raise the temperature, so that the central region and the flowing boundary region of fluid in the process of flowing of transformer oil in the inner pipe and between the inner pipe and the outer pipe are simultaneously heated, the transformer oil is heated more uniformly, and the temperature uniformity in the process of heating the transformer oil is improved.
2) According to the invention, the upper cover plate 7 and the lower cover plate 8 are effectively contacted with the outer wall surface of the inner tube 2, so that heat generated by the inner tube 2 due to electromagnetic induction heating is transferred to the upper cover plate 7 and the lower cover plate 8, and on one hand, the heat exchange area is increased by utilizing the expansion surfaces of the fins of the upper cover plate 7 and the lower cover plate 8; on the other hand, the fin heights of the upper cover plate 7 and the lower cover plate 8 are utilized to transfer the heat on the upper cover plate 7 and the lower cover plate 8 to a central fluid area far away from the heating wall surface, so that the temperature uniformity of the central flow area and the heating wall surface of the transformer oil is improved, the flow of the transformer oil is disturbed, and the heat transfer performance is enhanced.
3) The invention utilizes the enhanced heat transfer performance, reduces the heat transfer thermal resistance, increases the convection heat transfer area and improves the temperature uniformity in the flowing heat transfer process of the transformer oil, and compared with the traditional electromagnetic induction heating device of the transformer oil, the invention can avoid the phenomenon of local high-temperature hot spots caused by small heat transfer area and large heat flow density and prevent the transformer oil from going bad, therefore, compared with the traditional electromagnetic induction heating device of the transformer oil, the device of the invention can apply larger power supply power, improve the electromagnetic induction heating power and save the time cost of the circulating drying of the hot oil of the transformer oil.
Drawings
Fig. 1 is a schematic diagram of an oil heating device of a bushing type transformer based on an electromagnetic induction heating principle according to the present invention.
Fig. 2 is an assembly relation diagram of the oil heating device of the bushing type transformer based on the electromagnetic induction heating principle.
Fig. 3 is a schematic view of the inner tube structure.
Fig. 4 is a schematic view of the structure of the outer tube.
FIG. 5 is a schematic view of an electromagnetic coil wound around the outer wall of the inner tube.
Fig. 6 is a schematic diagram of an electromagnetic induction coil wound on the outer wall surface of the outer tube.
Fig. 7a is a schematic view of the upper cover plate contacted with the outer wall surface of the inner tube.
FIG. 7b is a schematic view of the lower cover plate contacting the outer wall surface of the inner tube.
Fig. 8 is a schematic view of the insulating support for fixing the inner tube.
Detailed Description
The invention is described in detail below with reference to the following figures and detailed description:
as shown in fig. 1, 2 and 3, a bushing-type transformer oil heating device based on an electromagnetic induction heating principle includes an outer tube 1 and an inner tube 2 of a bushing-type structure, the inner tube 2 is coaxially fixed on an inner wall surface of the outer tube 1 through an insulating support 6 (the structure of the insulating support 6 is shown in fig. 8), and an outer tube electromagnetic induction coil 3 and an inner tube electromagnetic induction coil 4 are respectively wound on outer wall surfaces of the outer tube 1 and the inner tube 2; as shown in fig. 7a and 7b, the outer wall surface of the inner tube 2 is provided with grooves (as shown in fig. 3) at a plurality of positions along the axial direction, which are used for installing an upper cover plate 7 and a lower cover plate 8 which are semi-circularly bent and have fins on the periphery, respectively, the upper cover plate 7 and the lower cover plate 8 form an integral column to wrap the inner tube electromagnetic induction coil 4, the inner tube electromagnetic induction coil 4 is isolated from the transformer oil, and the iron loss heat generated by the inner tube 2 under the action of electromagnetic induction is transferred to the ribs of the upper cover plate 7 and the lower cover plate 8 to heat the transformer oil between the outer tube 1 and the inner tube 2; according to the requirement of electromagnetic induction heating, different alternating currents and voltages are connected to realize the alternating change of the magnetic field in the sleeve structure, and joule heat is generated to increase the temperature of the outer pipe 1 and the inner pipe 2 of the sleeve structure so as to heat the transformer oil.
As shown in fig. 2, as a preferred embodiment of the present invention, the inner wall surface of the inner tube 2 is provided with a thread groove to enlarge the contact area between the inner wall surface of the inner tube and the transformer oil flowing in the inner tube, so as to break the boundary layer of the transformer oil flow, suppress the increase of the boundary layer, and improve the strength of the convection heat transfer in the tube.
In a preferred embodiment of the present invention, a space between the outer wall surface of the inner tube 2 and the upper cover plate 7 and the lower cover plate 8, in which the electromagnetic induction coil 4 is wound, is filled with a metal or non-metal material having a high thermal conductivity, so as to reduce natural convection of air in the space and reduce thermal resistance of the outer wall surface of the inner tube 2 in transferring heat to the upper cover plate 7 and the lower cover plate 8.
As a preferred embodiment of the invention, the shape and structural size parameters of the upper cover plate 7 and the lower cover plate 8 are optimized, the convection heat transfer coefficient between the upper cover plate 7 and the lower cover plate 8 and the transformer oil is further improved, and the convection heat transfer is enhanced.
As a preferred embodiment of the invention, the contact surfaces of the outer wall surface of the inner tube 2 and the upper cover plate 7 and the lower cover plate 8 are coated with thermal interface materials, so that the contact thermal resistance caused by poor contact and machining precision is reduced, and the thermal resistance in the heat conduction process is reduced.
In a preferred embodiment of the present invention, the upper cover plate 7 and the lower cover plate 8 are made of a metal material with high thermal conductivity, and as shown in fig. 7a, an inner lead hole 10 is drilled in the upper cover plate 7 to lead out the inner tube electromagnetic induction coil 4.
As shown in fig. 4, as a preferred embodiment of the present invention, an outer tube lead hole 9 is drilled on the outer wall surface of the outer tube 1, the inner tube electromagnetic induction coil 4 is led out to the external environment, and a sealing member 5 is installed at the position of the outer tube lead hole 9 to prevent the transformer oil from leaking from the outer tube lead hole 9.
In a preferred embodiment of the present invention, the outer tube 1 and the inner tube 2 are made of a low-carbon steel material having a low electric resistance.
As shown in fig. 5, the inner pipe electromagnetic induction coil 4 wound around the outer wall surface of the inner pipe 2 is composed of a plurality of electromagnetic induction coils by installing an upper cover plate 7 and a lower cover plate 8 on the inner pipe.
As shown in fig. 6, the inner pipe electromagnetic induction coil wound around the outer wall surface of the outer pipe 1 is an integrated electromagnetic induction coil.
The invention provides a bushing type transformer oil heating device based on an electromagnetic induction heating principle, taking a transformer oil heating process as an example, the bushing type transformer oil heating device comprises the following heat transfer processes:
(1) alternating current and voltage are introduced into the outer pipe electromagnetic induction coil 3 and the inner pipe electromagnetic induction coil 4, an alternating magnetic field is generated inside the induction coils due to self-induction of the outer pipe electromagnetic induction coil 3 and the inner pipe electromagnetic induction coil 4, the outer pipe 1 and the inner pipe 2 generate eddy current under the action of the alternating magnetic field, current density is mainly concentrated on the outer wall surfaces of the outer pipe 1 and the inner pipe 2 due to skin effect, joule heat is generated by the outer pipe 1 and the inner pipe 2, and the temperature of the outer pipe 1 and the temperature of the inner pipe 2 are increased;
(2) the temperature of the inner tube 2 rises, heat is transferred to the transformer oil flowing in the tube in a convection heat exchange mode, and the thread structure on the inner wall surface of the inner tube 2 enhances the heat exchange in the tube; the inner pipe 2 transmits a part of heat to the upper cover plate 7 and the lower cover plate 8 in a heat conduction mode, the temperature of the upper cover plate 7 and the lower cover plate 8 is raised, and the heat is transmitted to the transformer oil flowing between the inner pipe 2 and the outer pipe 1 in a convection heat exchange mode;
(3) the temperature of the outer pipe 1 rises, most of heat is transferred to the transformer oil flowing between the outer pipe 1 and the inner pipe 2 in a convection heat exchange mode, and a small part of heat is transferred to the surrounding environment in a natural convection and heat radiation mode of the outer wall surface of the outer pipe 1;
(4) the transformer oil flows in from the inlet of the heating device, and after being heated, the transformer oil flowing in the inner tube 2 is mixed with the transformer oil flowing between the outer tube 1 and the inner tube 2 at the outlet;
(5) the sleeve type transformer oil heating device is connected with the gear oil pump and the oil tank to form a circulating heating system, and the circulating heating of the transformer oil is completed.
Claims (8)
1. The utility model provides a bushing type transformer oil heating device based on electromagnetic induction heating principle which characterized in that: the electromagnetic induction type electromagnetic induction heating pipe comprises an outer pipe (1) and an inner pipe (2) which are of a sleeve type structure, wherein the inner pipe (2) is coaxially fixed on the inner wall surface of the outer pipe (1) through an insulating support (6), and an outer pipe electromagnetic induction coil (3) and an inner pipe electromagnetic induction coil (4) are respectively wound on the outer wall surfaces of the outer pipe (1) and the inner pipe (2); grooves are formed in the outer wall surface of the inner pipe (2) at a plurality of positions along the axial direction in an up-and-down mode and are used for installing an upper cover plate (7) and a lower cover plate (8) which are bent in a semicircular mode and provided with fins on the peripheries respectively, the upper cover plate (7) and the lower cover plate (8) form an integral column to wrap the inner pipe electromagnetic induction coil (4), the inner pipe electromagnetic induction coil (4) is isolated from transformer oil, and iron loss heat generated by the inner pipe (2) under the action of electromagnetic induction is transferred to the fins of the upper cover plate (7) and the lower cover plate (8) to heat the transformer oil between the outer pipe (1) and the inner pipe (2); according to the requirement of electromagnetic induction heating, different alternating currents and voltages are connected to realize the alternating change of the magnetic field in the sleeve structure, and joule heat is generated to increase the temperature of an outer pipe (1) and an inner pipe (2) of the sleeve structure so as to heat transformer oil.
2. The bushing type transformer oil heating apparatus based on electromagnetic induction heating principle of claim 1, wherein: the inner wall surface of the inner tube (2) is provided with a thread groove to enlarge the contact area between the inner wall surface of the inner tube and the transformer oil flowing in the inner tube, break the flowing boundary layer of the transformer oil, inhibit the growth of the boundary layer and improve the convective heat transfer intensity in the tube.
3. The bushing type transformer oil heating apparatus based on electromagnetic induction heating principle of claim 1, wherein: and a space between the outer wall surface of the inner pipe (2) and the upper cover plate (7) and the lower cover plate (8) and wound with the electromagnetic induction coil (4) is filled with a metal or non-metal material with high heat conductivity so as to reduce natural convection of air in the space and reduce thermal resistance of the outer wall surface of the inner pipe (2) for transferring heat to the upper cover plate (7) and the lower cover plate (8).
4. The bushing type transformer oil heating apparatus based on electromagnetic induction heating principle of claim 1, wherein: the shape and the structural size parameters of the upper cover plate (7) and the lower cover plate (8) are optimized, the convection heat transfer coefficient between the upper cover plate (7) and the lower cover plate (8) and the transformer oil is further improved, and the convection heat transfer is strengthened.
5. The bushing type transformer oil heating apparatus based on electromagnetic induction heating principle of claim 1, wherein: and a thermal interface material is coated on the contact surface of the outer wall surface of the inner pipe (2) and the upper cover plate (7) and the lower cover plate (8) so as to reduce the contact thermal resistance caused by poor contact and machining precision and reduce the thermal resistance in the heat conduction process.
6. The bushing type transformer oil heating apparatus based on electromagnetic induction heating principle of claim 1, wherein: the upper cover plate (7) and the lower cover plate (8) are made of metal materials with high thermal conductivity, and an inner lead hole (10) is drilled in the upper cover plate (7) to lead out the inner tube electromagnetic induction coil (4); outer tube pin hole (9) have been bored on outer tube (1) outer wall, in drawing out outer environment with inner tube electromagnetic induction coil (4), install sealing member (5) in outer tube pin hole (9) position, prevent that transformer oil from revealing in outer tube pin hole (9).
7. The bushing type transformer oil heating apparatus based on electromagnetic induction heating principle of claim 1, wherein: the outer pipe (1) and the inner pipe (2) are made of low-resistance low-carbon steel materials.
8. The method of heating transformer oil of the bushing type transformer oil heating apparatus based on the electromagnetic induction heating principle as set forth in any one of claims 1 to 8, wherein: the method comprises the following steps:
(1) alternating current and voltage are introduced into the outer pipe electromagnetic induction coil (3) and the inner pipe electromagnetic induction coil (4), the outer pipe electromagnetic induction coil (3) and the inner pipe electromagnetic induction coil (4) enable the induction coil to generate an alternating magnetic field due to self-induction phenomenon, the outer pipe (1) and the inner pipe (2) generate eddy current under the action of the alternating magnetic field, current density is mainly concentrated on the outer wall surfaces of the outer pipe (1) and the inner pipe (2) due to skin effect, the outer pipe (1) and the inner pipe (2) generate joule heat, and the temperature of the outer pipe (1) and the temperature of the inner pipe (2) are increased;
(2) the temperature of the inner tube (2) rises, heat is transferred to the transformer oil flowing in the tube in a convection heat exchange mode, and the thread structure on the inner wall surface of the inner tube (2) enhances the heat exchange in the tube; the inner pipe (2) transmits a part of heat to the upper cover plate (7) and the lower cover plate (8) in a heat conduction mode, the temperature of the upper cover plate (7) and the temperature of the lower cover plate (8) are increased, and the heat is transmitted to transformer oil flowing between the inner pipe (2) and the outer pipe (1) in a heat convection mode;
(3) the temperature of the outer pipe (1) rises, most of heat is transferred to the transformer oil flowing between the outer pipe (1) and the inner pipe (2) in a convection heat exchange mode, and a small part of heat is transferred to the surrounding environment in a natural convection and heat radiation mode of the outer wall surface of the outer pipe (1);
(4) the transformer oil flows in from the inlet of the heating device, and after being heated, the transformer oil flowing in the inner pipe (2) is mixed with the transformer oil flowing between the outer pipe (1) and the inner pipe (2) at the outlet;
(5) the sleeve type transformer oil heating device is connected with the gear oil pump and the oil tank to form a circulating heating system, and the circulating heating of the transformer oil is completed.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010569774.1A CN111556600A (en) | 2020-06-20 | 2020-06-20 | Sleeve type transformer oil heating device and method based on electromagnetic induction heating principle |
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| CN202010569774.1A CN111556600A (en) | 2020-06-20 | 2020-06-20 | Sleeve type transformer oil heating device and method based on electromagnetic induction heating principle |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113075009A (en) * | 2021-03-23 | 2021-07-06 | 中北大学 | Die inductive-resistant choke device formed by extrusion molding of Gleeble-3500 testing machine |
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