CN117848038A - Superconducting medium-frequency induction heating furnace - Google Patents

Abstract

The utility model provides a superconductive intermediate frequency induction heating furnace, including the furnace shell, the furnace shell inboard is provided with the low temperature insulating layer, the low temperature insulating layer inboard is provided with bakelite dewar casing, be provided with an annular inner chamber and a circular inner chamber in the bakelite dewar casing, the annular inner chamber is located the periphery of circular inner chamber, be provided with superconducting coil subassembly in the annular inner chamber of bakelite dewar casing, superconducting coil subassembly includes coil braced frame, the winding has superconducting coil on the coil braced frame, superconducting coil's both ends are connected with the current lead respectively, the injection has liquid nitrogen in the annular inner chamber of bakelite dewar casing, superconducting coil is immersed in liquid nitrogen, be provided with fire-resistant insulating layer in the circular inner chamber of bakelite dewar casing. The induction coil of the medium-frequency induction heating furnace is manufactured by adopting the high-temperature superconducting wire strip material, the copper cable coil used in the traditional medium-frequency furnace is replaced, the liquid nitrogen cooling superconducting wire strip material is used for replacing the traditional water cooling, the workpiece can be rapidly heated in a short time, and the generated loss is extremely low.

Description

A superconducting medium frequency induction heating furnace

Technical Field

The invention relates to the field of physics, in particular to a heating device, in particular to a superconducting medium frequency induction heating furnace.

Background technique

Medium frequency heating furnaces generally use medium frequency power supplies of 100-10000 Hz for induction heating, melting and heat preservation. They are the main equipment in casting, forging and heat treatment workshops. They are widely used in casting and melting. They can be used for melting and heating precious metals such as gold, silver, copper, iron, stainless steel, aluminum alloys and other metal materials. They are ideal equipment for precision casting processing. When melting metal, the medium frequency heating furnace uses a medium frequency power supply to establish a medium frequency magnetic field, so that induced eddy currents are generated inside the conductor and heat is generated, thereby achieving the purpose of heating the workpiece. The induction coil of the medium frequency furnace in the prior art uses a copper coil, which has resistance itself. Therefore, in the process of applying medium and high frequency currents to heat the workpiece, the furnace body itself will generate a large amount of heat and directly discharge it to the outside, resulting in a large amount of loss, resulting in a great waste of energy.

Summary of the invention

The object of the present invention is to provide a superconducting medium frequency induction heating furnace, which can solve the technical problem of large energy loss of medium frequency heating furnaces in the prior art.

A superconducting medium-frequency induction heating furnace of the present invention comprises a furnace shell, a low-temperature heat-insulating layer is arranged on the inner side of the furnace shell, a bakelite dewar shell is arranged on the inner side of the low-temperature heat-insulating layer, an annular inner cavity and a circular inner cavity are arranged in the bakelite dewar shell, the annular inner cavity is located at the outer periphery of the circular inner cavity, a superconducting coil assembly is arranged in the annular inner cavity of the bakelite dewar shell, the superconducting coil assembly comprises a coil support frame, a superconducting coil is wound on the coil support frame, current leads are connected to the two ends of the superconducting coil respectively, liquid nitrogen is injected into the annular inner cavity of the bakelite dewar shell, the superconducting coil is immersed in the liquid nitrogen, a refractory heat-insulating layer is arranged in the circular inner cavity of the bakelite dewar shell, the refractory heat-insulating layer is coaxially arranged with the superconducting coil, an opening is arranged on the upper side of the refractory heat-insulating layer, and a refractory heat-insulating cover is arranged on the opening.

Furthermore, copper terminal blocks are fixedly provided on both sides of the coil support frame, and two current leads are connected to two ends of the superconducting coil through the two copper terminal blocks, respectively. The copper terminal blocks and the current leads constitute a copper plate lead structure.

Furthermore, the coil supporting frame is made of stainless steel material.

Furthermore, the coil material of the superconducting coil is a superconducting wire or a superconducting tape having a critical temperature higher than the temperature of liquid nitrogen.

Furthermore, the material of the superconducting tape includes at least one of bismuth strontium calcium copper oxide and yttrium barium copper oxide.

Furthermore, the thickness of the superconducting layer of the superconducting tape composed of yttrium barium copper oxide is 1 μm, and the width of the superconducting tape composed of yttrium barium copper oxide is 4.8 mm.

Furthermore, a cylindrical crucible is coaxially arranged in the inner cavity of the refractory insulation layer.

Furthermore, the refractory heat-insulating layer and the refractory heat-insulating cover are both made of aluminum silicate refractory material.

Compared with the prior art, the present invention has a positive and obvious effect. The present invention uses high-temperature superconducting wire strips to make medium-frequency induction heating furnace induction coils, replacing the copper cable coils used in traditional medium-frequency furnaces, and uses liquid nitrogen to cool the superconducting wire strips instead of traditional water cooling, which can quickly heat the workpiece in a short time. Compared with traditional medium-frequency furnaces, the present invention has extremely low losses, greatly improving the problem of large losses in traditional medium-frequency furnaces, and has great significance for the field of medium-frequency furnace technology and the application of high-temperature superconductors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic cross-sectional view of a superconducting medium frequency induction heating furnace of the present invention.

FIG. 2 is a three-dimensional schematic diagram of a superconducting medium-frequency induction heating furnace of the present invention.

FIG3 is a three-dimensional schematic diagram of a superconducting coil assembly in a superconducting medium frequency induction heating furnace of the present invention.

FIG4 is a schematic diagram of a portion to be heated in a superconducting medium frequency induction heating furnace of the present invention.

Explanation of reference numerals: 1-superconducting coil; 2-coil support frame; 3-copper plate lead structure; 4-bakelite dewar shell; 5-workpiece to be heated; 6-crucible; 7-refractory insulation layer; 8-refractory insulation cover; 9-low-temperature insulation layer; 10-furnace shell.

Detailed ways

The present invention is further described below in conjunction with an embodiment, but the present invention is not limited to the embodiment, and any similar structure and similar changes of the present invention should be included in the protection scope of the present invention. The use of directions such as up, down, front, back, left, and right in the present invention is only for the convenience of clear description and is not a limitation of the technical solution of the present invention.

As shown in Figures 1 to 4, a superconducting medium-frequency induction heating furnace of the present invention includes a furnace shell 10, a low-temperature thermal insulation layer 9 is arranged on the inner side of the furnace shell 10, a bakelite dewar shell 4 is arranged on the inner side of the low-temperature thermal insulation layer 9, an annular inner cavity and a circular inner cavity are arranged in the bakelite dewar shell 4, the annular inner cavity is located at the outer periphery of the circular inner cavity, a superconducting coil assembly is arranged in the annular inner cavity of the bakelite dewar shell 4, the superconducting coil assembly includes a coil support skeleton 2, a superconducting coil 1 is wound on the coil support skeleton 2, current leads are respectively connected to the two ends of the superconducting coil 1, liquid nitrogen is injected into the annular inner cavity of the bakelite dewar shell 4, the superconducting coil 1 is immersed in the liquid nitrogen, a refractory thermal insulation layer 7 is arranged in the circular inner cavity of the bakelite dewar shell 4, the refractory thermal insulation layer 7 is coaxially arranged with the superconducting coil 1, an opening is arranged on the upper side of the refractory thermal insulation layer 7, and a refractory thermal insulation cover 8 is arranged on the opening.

Furthermore, copper terminal blocks are fixedly provided on both sides of the coil support frame 2, and two current leads are connected to two ends of the superconducting coil through the two copper terminal blocks, respectively. The copper terminal blocks and the current leads constitute a copper plate lead structure 3.

Furthermore, the coil supporting frame 2 is made of stainless steel.

Furthermore, the coil material of the superconducting coil 1 is a superconducting wire or a superconducting tape having a critical temperature higher than the temperature of liquid nitrogen.

Furthermore, the material of the superconducting tape includes at least one of bismuth strontium calcium copper oxide (BSCCO) and yttrium barium copper oxide (YBCO).

Furthermore, the thickness of the superconducting layer of the superconducting tape composed of yttrium barium copper oxide is 1 μm, and the width of the superconducting tape composed of yttrium barium copper oxide is 4.8 mm.

Furthermore, a cylindrical crucible 6 is coaxially arranged in the inner cavity of the refractory insulation layer 7 .

Furthermore, the fire-resistant heat-insulating layer 7 and the fire-resistant heat-insulating cover 8 are both made of aluminum silicate refractory material.

Specifically, Dewar is a professional abbreviation for cryogenic Dewar flask or cryogenic Dewar container, which is specially used to hold or store cryogenic liquids. The structure requires good insulation and low-temperature performance. It belongs to the existing technology and is well known to technicians in the cryogenic field. Bakelite Dewar refers to a low-temperature Dewar container that is assembled from bakelite materials for special occasions. Bakelite has good low-temperature insulation and mechanical properties and is commonly used in low-temperature cylindrical and annular containers.

Specifically, the current lead, liquid nitrogen, low-temperature insulation layer 9, refractory insulation layer 7, copper plate lead structure 3, superconducting wire, superconducting tape, bismuth strontium calcium copper oxide (BSCCO), yttrium barium copper oxide (YBCO), aluminum silicate refractory material, etc. in this embodiment all adopt well-known solutions in the prior art, which are well understood by those skilled in the art and will not be described in detail here.

The working principle of this embodiment:

The superconducting coil 1, together with the copper plate lead structure 3, the current lead, and the coil support frame 2 are placed in the annular inner cavity of the bakelite dewar shell 4 to form a complete superconducting coil assembly. Liquid nitrogen is injected into the annular inner cavity of the bakelite dewar shell 4 to maintain a low-temperature environment for the superconducting coil 1 by contact. The workpiece 5 to be heated is placed in the crucible 6, and the crucible 6 is placed in the refractory insulation layer 7, and covered with a refractory insulation cover 8 to play a role in heat insulation and sealing, so that the workpiece 5 is isolated from the external environment and the heat transfer of the high-temperature heat source to the low-temperature environment and the outside world is suppressed. The crucible 6 is located in the central area of the superconducting coil 1, and the current lead excites the superconducting coil 1 through an external power supply to heat the workpiece 5 placed in the medium frequency furnace.

The furnace shell 10 protects and fixes the internal components. The superconducting coil 1 is supported by the coil support frame 2, which does not affect the magnetic flux distribution. The entire superconducting coil 1 should maintain a low temperature environment of 77 K.

Each group of superconducting coils 1 composed of yttrium barium copper oxide is wound by 100 turns of superconducting tape, with a total of 10 groups. The workpiece 5 is a copper ingot with a radius of 150 mm and a height of 42 mm, and is induction heated by a 300 Hz medium frequency power supply. An alternating current less than the critical current of the superconducting tape is passed through each turn of the superconducting coil 1 for excitation, and an alternating current with an amplitude of 150 A is applied. The initial temperature T ₀ =300 K. When the radius of the workpiece 5 is 150 mm, the time for the edge of the workpiece 5 to be heated to 1000°C is 5.05 s, the maximum heating power of the copper ingot reaches 182 kW, and the instantaneous maximum AC loss corresponding to the superconducting coil 1 is 1.1 kW. When a conventional medium frequency furnace coil (taking a copper coil as an example) of the same size as the superconducting coil 1 of this embodiment is used, the AC loss generated under the same circumstances is 655 kW, which greatly reduces energy loss.

High-temperature superconducting materials have great application prospects in the power, magnet, energy storage, power, nuclear fusion and other industries due to their advantages such as large current carrying capacity, high critical magnetic field and high critical temperature. Superconducting materials can be widely used in large-scale power equipment due to their unimpeded high current density characteristics, which can greatly reduce losses. With the continuous rise of green energy-saving and environmental protection industries, the performance, output and stability of superconducting tapes are constantly improving. It is generally believed that high-temperature superconducting materials will soon usher in large-scale applications.

The present invention adopts high-temperature superconducting wire strips to make induction coils of medium-frequency induction heating furnaces, replacing copper cable coils used in traditional medium-frequency furnaces, and uses liquid nitrogen to cool superconducting wire strips instead of traditional water cooling, so that workpieces can be quickly heated in a short time. Compared with traditional medium-frequency furnaces, the present invention has extremely low losses, greatly improves the problem of large losses in traditional medium-frequency furnaces, and has great significance to the technical field of medium-frequency furnaces and the application of high-temperature superconductors.

Claims (8)

1. A superconducting medium frequency induction heating furnace, characterized in that it includes a furnace shell, a low-temperature insulation layer is arranged on the inner side of the furnace shell, a bakelite Dewar shell is arranged on the inner side of the low-temperature insulation layer, an annular inner cavity and a circular inner cavity are arranged in the bakelite Dewar shell, the annular inner cavity is located at the outer periphery of the circular inner cavity, a superconducting coil assembly is arranged in the annular inner cavity of the bakelite Dewar shell, the superconducting coil assembly includes a coil support frame, a superconducting coil is wound on the coil support frame, current leads are connected to the two ends of the superconducting coil respectively, liquid nitrogen is injected into the annular inner cavity of the bakelite Dewar shell, the superconducting coil is immersed in the liquid nitrogen, a refractory insulation layer is arranged in the circular inner cavity of the bakelite Dewar shell, the refractory insulation layer is coaxially arranged with the superconducting coil, an opening is arranged on the upper side of the refractory insulation layer, and a refractory insulation cover is arranged on the opening. 2. A superconducting medium frequency induction heating furnace according to claim 1, characterized in that: copper terminal blocks are fixedly provided on both sides of the coil support frame, and two current leads are connected to the two ends of the superconducting coil through the two copper terminal blocks respectively, and the copper terminal blocks and the current leads constitute a copper plate lead structure. 3. A superconducting medium frequency induction heating furnace according to claim 1, characterized in that the coil support frame is made of stainless steel. 4. A superconducting medium frequency induction heating furnace according to claim 1, characterized in that the coil material of the superconducting coil is a superconducting wire or a superconducting tape whose critical temperature is higher than the temperature of liquid nitrogen. 5. A superconducting medium frequency induction heating furnace according to claim 4, characterized in that the material of the superconducting tape comprises at least one of bismuth strontium calcium copper oxide and yttrium barium copper oxide. 6. A superconducting medium frequency induction heating furnace according to claim 5, characterized in that the thickness of the superconducting layer of the superconducting tape composed of yttrium barium copper oxide is 1 μm, and the width of the superconducting tape composed of yttrium barium copper oxide is 4.8 mm. 7. A superconducting medium frequency induction heating furnace according to claim 1, characterized in that a cylindrical crucible is coaxially arranged in the inner cavity of the refractory insulation layer. 8. A superconducting medium frequency induction heating furnace according to claim 1, characterized in that the refractory insulation layer and the refractory insulation cover are both made of aluminum silicate refractory material.