Liquid three-phase power frequency double-loop electromagnetic induction and short circuit heating device

Abstract

The utility model relates to a three-phase power frequency double-loop electromagnetic induction and short circuit heating device for liquid. The heating device is provided with an iron core, and a three-phase primary winding is wound on a core column of the iron core; and the metal shell is arranged along the three-phase closed magnetic loop to form a double-loop shell structure which surrounds the iron core and the three-phase primary winding and is provided with ten secondary side short-circuit metal rings. During operation, short-circuit large current is induced and generated in the metal rings with the short-circuited secondary sides; each secondary side is conducted through the same metal shell to generate phase-to-phase and three-phase short-circuit heavy current; the short-circuit current directions of the inner and outer secondary sides of each phase are the same, and the magnetic leakage directions of the adjacent secondary sides are opposite to form a strong and stable three-phase power frequency alternating N-S magnetic field, so that the leakage magnetism is greatly reduced, and the temperature rise of the protective shell is greatly reduced; a medium flows through the heating device, and is magnetized by a strong alternating magnetic field without scaling while being heated; the surface load parameter is greatly reduced, and the single-machine design power is effectively expanded.

Description

Technical Field

[0001] The utility model relates to a power frequency electromagnetic induction and short circuit heating device and a heating method, more precisely to a liquid three-phase power frequency double-circuit electromagnetic induction and short circuit heating device and a heating method for heating liquid. Background Art

[0002] In the power transformer manufacturing industry, there is a recognized "6-degree rule", which means that if the temperature exceeds the rated temperature by 6°C, the life span will be shortened by half; if the temperature is below the rated temperature by 6°C, the life span will be doubled.

[0003] Chinese patent document CN1142706C (patent application number 01134187.4, hereinafter referred to as Patent Document 1) discloses a three-phase power-frequency electromagnetic induction and short-circuit heating device and method for liquid heating. Its operating principle is to provide low voltage and high current to the secondary side based on the primary-to-secondary turns ratio of the transformer. In the aforementioned patent, each secondary side has one turn and is short-circuited to form a loop, hence the term "short-circuit (single-loop) heating." In transformer terminology, the portion of the core with windings is called the core leg, while the portion of the core without windings that only forms a closed magnetic loop is called the yoke. The aforementioned patent innovatively utilizes a metal casing as the secondary side, enclosing the core and primary windings along the three-phase closed magnetic loop. This creates three short-circuited secondary metal rings on the core leg and four short-circuited secondary metal rings on the yoke, resulting in a heating device with seven secondary short-circuits (hereinafter referred to as the "seven-secondary short-circuit heating device").

[0004] When the primary side of the above-mentioned heating device is connected to a three-phase industrial frequency power supply, the secondary metal rings of the metal shell induce a short-circuit high current; the secondary metal rings of each phase are connected through the same metal shell to generate a short-circuit high current between phases and between three phases; the above two different short-circuit high currents cause the metal shell to be rapidly heated, and then the metal shell conducts the Joule heat to the surrounding liquid medium; the vector sum of the three-phase short circuit formed by the above-mentioned secondary sides is equal to zero, and it has zero potential during operation, which is safe.

[0005] The positive effects of the above patent are mentioned as follows: In thermal design, there is a surface load parameter, which means the heat dissipation (dissipation) power per unit area. The larger the surface area, the greater the margin of the design output power. Using the shell as the main heating element should achieve a design that maximizes power. Indeed, the above patent has achieved a maximized design, but its output power is not proportional to the shell surface area. This can be seen from the relationship between the core cross section S and the output power P in the patent. It can be understood that the greater the output power, the higher the surface load parameter, and the higher the temperature rise of the primary winding. When the temperature rise of the primary winding reaches the rated temperature rise, the maximization of the designed output power is limited. Furthermore, the temperature rise of each part of the above-mentioned metal shell is not uniform. From Experimental Example 2 No. 2, it can be seen that after cutting off the four secondary metal rings at the yoke part, the shell with three secondary sides at the core leg part is measured. Its output power accounts for 85.26% of the whole machine, while its surface area accounts for only 72.5% of the whole machine. It can be seen that the shell at the core leg part generates the most heat and has the highest surface load parameter.

[0006] Chinese patent document CN102384577A (patent number ZL201110340219.2, hereinafter referred to as Patent Document 2) discloses a three-phase, industrial-frequency electromagnetic dual-induction heating device for liquids. Its operating principle is to utilize ferromagnetic metal plates, which possess both excellent magnetic conductivity and the ability to generate eddy currents and hysteresis, surrounding the seven-side short-circuit heating device to form a magnetically conductive frame. During operation, the magnetically conductive frame induces the short-circuit leakage magnetic flux generated by the seven-side short-circuit heating device to form a loop with it, inducing eddy currents and hysteresis within the magnetic conductive frame, thereby forming an eddy current heating device. This device, along with the seven-side short-circuit heating device, simultaneously heats the liquid medium flowing through it. Specifically, the seven-side short-circuit heating device is connected to a three-phase industrial-frequency power supply, and the liquid is heated by both the short-circuit and eddy current induction heating devices. This effectively controls and utilizes the short-circuit leakage magnetic flux within the magnetic conductive frame. The positive effects of the above patent are mentioned as follows: the output power is 131.09kw, and the temperature rise of the protective shell drops from 57k to 15k, which is indeed a significant drop. However, the temperature rise of the protective shell is almost proportional to the output power. The national standard for the temperature rise of the protective shell of a commercial heating device stipulates that it should not exceed 50k, so the designed output power is limited.

[0007] The single-loop power-frequency short-circuit magnetic flux leakage in the two aforementioned patents significantly impacts the temperature rise of the protective housing, but has limited magnetizing effect on the liquid medium flowing through it. This leads to soft scale buildup on the secondary housing over long-term operation. While this soft scale will naturally fall off, it will undoubtedly affect heat dissipation from the secondary housing, impact the temperature rise of the primary winding, and shorten its service life. However, despite the drawbacks of these two patents, the basic technical solutions they disclose are also an important component of this application. Utility Model Content

[0008] The purpose of this utility model is to overcome the shortcomings of the existing technology, and to further increase the output power of a single machine and reduce the kilowatt cost under the condition that the temperature rise of the winding and the temperature rise of the protective shell meet the relevant requirements of the national standard; under the condition of the same total installed capacity, the number of installed units is reduced, the expensive floor space is reduced, the initial investment cost is greatly reduced, and the commercial value is greater.

[0009] The technical solution for achieving the objectives of this utility model is as follows: This liquid-use three-phase power-frequency dual-circuit electromagnetic induction and short-circuit heating device comprises an EI-shaped core entirely constructed of laminated silicon steel sheets to form a closed three-phase magnetic circuit. A primary winding, i.e., a three-phase primary winding, is wound around each of the three core legs of the EI-shaped core. The three-phase primary windings, from left to right, are the U phase, the V phase, and the W phase. Its structural features are:

[0010] The EI-shaped core also includes a metal casing, comprising a first-circuit metal casing and a second-circuit metal casing. The first-circuit metal casing is arranged along the three-phase closed magnetic circuit, forming secondary metal rings for each phase surrounding the core and the primary windings of each phase. The second-circuit metal casing is arranged along the outer sides of the secondary windings of each phase on the three core legs of the first-circuit core. Thus, on the three core legs of the EI-shaped core, from the inside to the outside, the three-phase primary windings are surrounded, along with the three secondary metal rings for the first-circuit short-circuit (Ua, Va, and Wa, respectively, for the U, V, and W phases of the three-phase primary windings); the three secondary metal rings for the second-circuit short-circuit (Ub, Vb, and Wb, respectively, for the three secondary metal rings for the first-circuit short ...

[0011] In the above-mentioned three-phase power-frequency dual-circuit electromagnetic induction and short-circuit heating device for liquid, the first circuit metal housing comprises a first outer shell and two rectangular tubes. The second circuit metal housing comprises a second outer shell and two flow guides with folded fins at their front and rear ends. The height of the second outer shell is greater than the height of the folded fins of the flow guides, but less than the height of the first shell.

[0012] In the above-mentioned three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device for liquid, the guide member in the inner cavity of the rectangular tube has its upper and lower surfaces welded and fixed to the upper and lower inner folded fins of the rectangular tube, and the straight part of the guide member is spaced the same as the inner wall of the rectangular tube and is equal to the net height of the upper and lower inner folded fins of the rectangular tube; the folded fins in front and behind the guide member extend out of the front and rear end surfaces of the rectangular tube by a distance respectively, and are welded and fixed to the front and rear end surfaces of the rectangular tube.

[0013] In the above-mentioned liquid-use three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device, the rectangular tubes include a first rectangular tube and a second rectangular tube, and the left and right sides of the first rectangular tube and the second rectangular tube respectively form three short-circuited secondary metal rings (Ua, Va, Wa) surrounding the primary windings of each phase with the first shell; the flow guides include a first flow guide and a second flow guide, and the first flow guide and the second flow guide extend out of the front and rear end faces of the corresponding rectangular tubes by a distance, penetrate the front and rear faces of the second shell and are welded and fixed, and the second shell (4-2) is kept uniformly spaced from the four sides of the first shell; thus, the left and right sides of the two flow guides respectively form with the second shell on the outside of the three secondary short-circuited metal rings (Ua, Va, Wa) of the first circuit, and are parallel to the three short-circuited secondary metal rings (Ub, Vb, Wb) surrounding the three primary windings of the three phases to serve as the second main heating element.

[0014] By using the double-circuit structural method composed of the guide piece and the second shell of the three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device for liquid, a three-circuit or multi-circuit induction heating device with a larger single-unit capacity can be formed on the outside of the second shell.

[0015] In the above-mentioned three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device for liquid, the second shell and the flow guide are made of stainless steel plates with the same thickness as the first shell and the rectangular tube.

[0016] The technical solution for heating liquid using a three-phase power frequency dual-circuit electromagnetic induction and short-circuit heating device, which achieves the objectives of the present invention, is as follows: When the three-phase primary windings of the three-phase power frequency dual-circuit electromagnetic induction and short-circuit heating device are connected to a three-phase power frequency power supply, a high short-circuit current is induced in the ten short-circuited secondary metal coils of the dual-circuit metal casing. Each secondary winding of each phase is electrically conductive through the same metal casing, generating high short-circuit currents between phases and between the three phases. Under the combined action of these two high currents, the dual-circuit metal casing is rapidly heated, and the generated Joule heat is transferred to the surrounding liquid medium. The metal casing maintains a zero potential and serves as a protective casing and heat sink for the three-phase primary windings. The short-circuit currents on the inner and outer secondary windings of each phase of the dual-circuit circuit are directed in the same direction, while the magnetic flux leakage between adjacent secondary windings is directed in opposite directions. This creates a strong and stable three-phase power frequency alternating NS magnetic field loop, given the relatively short spacing between the inner and outer secondary windings of each phase of the dual-circuit circuit. This significantly reduces magnetic flux leakage and, consequently, the temperature rise of the protective casing. When the liquid medium flows through the dual-circuit secondary channel, it is simultaneously heated and magnetized by the powerful alternating magnetic field. The magnetized water does not form scale, and the magnetized oil does not form carbon. This dual-circuit induction short-circuit heating method significantly reduces surface load parameters and effectively increases the design power of a single unit.

[0017] The utility model has the following positive effects: (1) The heating device of the utility model has a shell structure with a double-circuit structure, which greatly reduces the surface load parameters and reduces the temperature rise of the winding. Thus, the margin of the output power of the single unit can be greatly improved. (2) The short-circuit current direction of the inner and outer secondary sides of each phase of the double circuit is the same, and the leakage magnetic direction between the adjacent ones is opposite. In this way, a strong and stable three-phase power frequency alternating NS magnetic field loop is formed under the condition that the distance between the inner and outer secondary sides of each phase of the double circuit is relatively short. As a result, the leakage magnetic flux is greatly reduced, and the temperature rise of the protective shell is also greatly reduced, which is safe. (3) When the liquid medium flows through this channel between the inner and outer secondary sides of the double circuit, it is magnetized by the strong alternating magnetic field while being heated. The magnetized water does not scale and the magnetized oil does not carbonize, which is beneficial to the heat dissipation conditions of the secondary side shell remaining unchanged for a long time, which is beneficial to the temperature rise of the winding and reliable. (4) Under the condition that the total installed capacity remains unchanged, the output power of the single unit is doubled and the floor space is reduced by 50%; and the greater the output power of the single unit, the lower the manufacturing cost per unit power. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the core and winding structure of the liquid three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device of the present invention.

[0019] Figure 2 This is a structural diagram of the rectangular tube and flow guide in the three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device for liquid of the utility model.

[0020] Figure 3 This is a structural diagram of the liquid three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device of the present invention.

[0021] Figure 4 For application Figure 3 The structure diagram of a circulating heating device of the utility model is shown as a three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device for liquid.

[0022] Figure 5 This is a schematic diagram of a complete set of products for the three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device for liquid of the utility model.

[0023] The figure marks in the above drawings are as follows: iron core 1, three-phase primary winding 2, upper plate 3-1, lower plate 3-2, first shell 4-1, second shell 4-2, rectangular tube 5, first rectangular tube 5a, second rectangular tube 5b, terminal block 6, insulating plate 7, lead wire 8, insulating filler 9, flow guide 10, first flow guide 10a, second flow guide 10b, inlet circular tube 11, outlet 12, circulation box 13, first base 14, circular hole 15, main water inlet pipe 16, L-shaped branch pipe 17, magnetic frame 18, protective shell 51, inlet temperature sensor 52, pressure sensor 53, machine base 54, drain valve 55, second base 56, outlet temperature sensor 57, electrical control box 60.

[0024] Heating device 30A, circulation heating device 50A, complete set of commercial products 100A. DETAILED DESCRIPTION

[0025] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "height", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0027] It is particularly important to point out that in the description of this application, the directions or positional relationships indicated by various terms are based on the attached Figure 1 Center view or attached Figure 3 The orientation or positional relationship shown in the center view.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0029] The following describes in detail the liquid three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device and heating method according to the present application with reference to the accompanying drawings.

[0030] (Example 1)

[0031] See also Figure 1 , Figure 1 The front and side views of the device illustrate the structure of the core 1 and three-phase primary winding 2 of the three-phase, industrial-frequency, dual-circuit electromagnetic induction and short-circuit heating device for liquid heating according to the present invention. The core 1 is EI-shaped and constructed entirely of laminated silicon steel sheets to form a closed three-phase magnetic circuit. A primary winding, i.e., a three-phase primary winding 2, is wound around each of the three legs of the EI-shaped core 1. The three-phase primary windings 2 are arranged from left to right in phase sequence, designated U, V, and W. The three-phase primary windings 2 can be connected in either a Y-star (W) or delta (△) configuration; the figure shows a Y-star (W) configuration.

[0032] See also Figure 2 , Figure 2 The figure shows a rectangular tube 5 with semi-enclosed ends and inwardly folded fins on the upper and lower surfaces of the three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device for liquid of the present invention. One end of the rectangular tube 5 is provided with at least four inlet circular tubes 11 as its inlet, and the other end is provided with at least five square holes as its outlet. A flow guide 10 with folded fins on both ends is provided in the inner cavity of the rectangular tube 5. The main part of the flow guide 10 is a hollow tube. The straight portion of the hollow tube is spaced the same as the inner wall of the rectangular tube 5 and is equal to the height of the upper and lower inwardly folded fins of the rectangular tube. The upper and lower surfaces of the flow guide 10 are welded to the upper and lower inwardly folded fins of the rectangular tube 5. The folded fins at both ends of the flow guide 10 extend out of the front and rear ends of the rectangular tube 5 by a spacing, and are welded to the front and rear end surfaces of the rectangular tube 5.

[0033] See also Figure 3 , Figure 3 The three views of the utility model show the three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device 30A for liquid. The three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device 30A for liquid has a first circuit metal shell and a second circuit metal shell. The first circuit metal shell is set along the three-phase closed magnetic circuit. It Figure 1 The core 1 and the primary winding 2 are all encapsulated in a metal shell composed of an upper plate 3-1, a lower plate 3-2, a first shell 4-1, a rectangular tube 5 and a terminal block 6; Figure 3In the figure, there are two rectangular tubes 5: a first rectangular tube 5a and a second rectangular tube 5b. Lead wires 8 for the three-phase primary windings extend from terminal blocks 6 through insulating plates 7. A certain insulation distance exists between the first circuit metal casing and the core 1 and primary winding 2. All spaces within the metal casing are filled with insulating filler 9, forming a fully enclosed entity. The second circuit metal casing consists of a second shell 4-2 and two flow guides 10 with folded wings at both ends. It is located along the outer side of the first circuit metal casing on the three core legs of the core 1.

[0034] Still see Figure 3 In this embodiment, except for the terminal block 6 and the inlet round tube 11, which are stainless steel tubes, the other parts of the metal shell are all made of stainless steel plates that are punched, pressed and then assembled; the preferred thickness of the stainless steel plates is 1.0 to 4.0 mm.

[0035] The terminal block 6 is welded to one side of the first shell 4-1; the upper plate 3-1 is welded to the upper end of the first shell 4-1, and the lower plate 3-2 is welded to the lower end of the first shell 4-1.

[0036] The rectangular tubes 5 include a first rectangular tube 5a and a second rectangular tube 5b. The first rectangular tube 5a and the second rectangular tube 5b are respectively arranged between the UV phase and the VW phase of the three-phase primary winding 2 and between the corresponding upper and lower yokes. The first rectangular tube 5a and the second rectangular tube 5b pass through the front and rear surfaces of the first shell 4-1, and the four sides of the front and rear ends are welded and fixed to the front and rear surfaces of the first shell 4-1 respectively. In this way, the upper surfaces of the two rectangular tubes 5, the first shell 4-1 and the upper plate 3-1 respectively form two short-circuited secondary metal rings surrounding the upper yoke; the lower surfaces of the two rectangular tubes 5, the first shell 4-1 and the lower plate 3-2 respectively form two short-circuited secondary metal rings surrounding the lower yoke. Figure 3 The figure shows two short-circuited secondary metal rings at the upper and lower parts of the UV phase.

[0037] See also Figure 3 The left and right surfaces of the first rectangular tube 5a and the second rectangular tube 5b and the first shell 4-1 respectively form three short-circuited secondary metal rings surrounding the primary winding 2 of each phase. The three secondary metal rings are Ua, Va, and Wa respectively.

[0038] The flow guide 10 comprises a first flow guide 10a and a second flow guide 10b. The folded wings of the first and second flow guides 10a and 10b extend a distance from the front and rear ends of the corresponding first and second rectangular tubes 5a and 5b, penetrate the front and rear surfaces of the second housing 4-2, and are welded to the housing. The spacing around the second housing 4-2 and the first housing 4-1 is uniform. The left and right sides of the two flow guides 10, along with the second housing 4-2, form three short-circuited secondary metal rings that surround the primary windings 2 of each phase in parallel with the first housing 4-1. These three secondary metal rings are designated Ub, Vb, and Wb, respectively, according to their phases. The metal housing of the heating device 30A is a dual-circuit housing structure with ten secondary metal rings. This significantly reduces surface load parameters and primary winding temperature rise while effectively increasing the design power of a single unit.

[0039] Still see Figure 3 The left side of the first rectangular tube 5a in the first circuit metal casing is the secondary short-circuit metal ring for the U phase, while the right side is the secondary short-circuit metal ring for the V phase. These two short-circuited secondary short-circuits are connected via the top, bottom, and front, back, and sides of the first rectangular tube 5a, forming a phase-to-phase short circuit between the secondary sides of the U and W phases. The secondary short-circuit metal rings for the V and W phases are connected via the top, bottom, and front, back, and sides of the second rectangular tube 5b, forming a phase-to-phase short circuit between the secondary sides of the V and W phases. The secondary short-circuit metal rings for the U and W phases are connected via the first housing 4-1, forming a phase-to-phase short circuit between the secondary sides of the U and W phases. These short-circuited secondary short-circuits are connected via the same metal casing, forming a three-phase short circuit, the sum of the three-phase short circuit vectors equaling zero. This means that the first circuit metal casing is at zero potential. It can be seen from this that the second shell 4-2 of the second circuit should be higher than the height of the folded wing of the flow guide 10 to reduce the influence of the electric field and magnetic field caused by the UW two-phase and three-phase short circuit.

[0040] Method for heating liquid using three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device 30: See also Figure 3, the liquid is immersed in the liquid with a three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device 30A except for the outlet of the terminal block. When its three-phase primary winding 2 is connected to the three-phase power frequency power supply, a large current is induced in the 10 short-circuited secondary metal rings of the inner and outer circuits; the secondary sides of each phase are connected through the same metal shell to generate a short circuit between phases and a three-phase short-circuit large current; under the combined action of the above two large currents, the double-circuit metal shell is rapidly heated, and the Joule heat generated thereby is transferred to the dielectric liquid around it, and the metal shell is at zero potential, and it is also the protective shell and heat sink of the three-phase primary winding 2; the double-circuit The short-circuit currents on the inner and outer secondary sides of each phase are in the same direction, while the leakage flux between adjacent sides is in opposite directions. Thus, under the condition that the spacing between the inner and outer secondary sides of each phase of the double circuit is relatively short, a strong and stable three-phase power frequency alternating NS magnetic field circuit is formed. As a result, the leakage flux is greatly reduced, and the temperature rise of the protective shell is also greatly reduced. When the liquid medium flows through the channel of the inner and outer secondary sides of the double circuit, it is magnetized by the strong alternating magnetic field while being heated. The magnetized water does not scale, and the magnetized oil does not carbonize. Compared with the original single-circuit heating method, this double-circuit heating method greatly improves the output power of the whole machine and significantly reduces the temperature rise of the winding while keeping the core cross-section unchanged.

[0041] (Application Example 1)

[0042] See also Figure 4 , Figure 4 The three views in the figure show a circulating heating device 50A assembled using the present invention. The three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device 30A for liquid of the present invention in Example 1 is taken and fixed on the first base 14 in the circulation box 13 with the magnetic frame 18. The water to be heated in the water tank (not shown in the figure) is pumped into the circulation box 13 through the main water inlet pipe 16 by the circulation pump and then discharged in three ways; one way is sprayed downward through the circular hole 15, diffused and then upward; the other two ways are through two L-shaped branches 17, through the 8 inlet circular tubes 11 of the three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device 30A for liquid of the present invention, enter the gap between the two rectangular tubes 5 and their respective guide members 10, and then discharged from the outlet at the other end of the two rectangular tubes 5. The three water flows pass through the inner and outer surfaces of the double-circuit metal shell of the liquid three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device 30A of the present invention, undergoing sufficient heat exchange, and the Joule heat generated is discharged from the outlet 12 along with the heated water and returned to the water tank. This cycle is repeated to heat the water in the water tank to the required temperature, thereby forming a circulating heating device 50A.

[0043] (Application Example 2)

[0044] See also Figure 5 , Figure 5The two views show a complete commercial product 100A using the three-phase power-frequency dual-circuit electromagnetic induction and short-circuit heating device for liquids of the present invention. The circulating heating device 50A of Application Example 1 is mounted on a base 54 with a protective housing 51. It is also mounted on the same second base 56 as the electrical control box 60, forming a fixed structure. An insulation layer (not shown) is provided between the circulating heating device 50A and the protective housing 51. A drain valve 55 is provided at the bottom of the circulating heating device 50A. An inlet temperature sensor 52 and a pressure sensor 53 are provided on the main water inlet pipe 16 of the circulating heating device 50A, and an outlet temperature sensor 57 is provided on the pipe at its outlet 12. The low-voltage electrical components selected for the accompanying electrical control box 60 can effectively detect fault signals such as short circuits, overcurrents, and leakage in the electrical system. Signals such as the outlet water temperature, the inlet and outlet water temperature difference, and the pressure detected by the aforementioned sensors are sent to a PLC program controller, which then issues control or alarm signals according to the compiled program, achieving unmanned, safe, and automatic operation.

[0045] (Test Example 1)

[0046] The single-circuit heating device described in Patent Document 2 mentioned in the background technology and the liquid-use three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device manufactured by the present invention were subjected to winding temperature rise tests and protective housing temperature rise tests respectively. The main test data are shown in Table 1 and Table 2 respectively:

[0047] Table 1 (single circuit)

[0048] Specifications (kw) 350 420 500 600 800 1100 Winding temperature rise (k) 51.7 60.1 67.8 73.9 80.5 88.2 Protective shell temperature rise (k) 39.0 47.5 55.6 67.6 89.5 112.8

[0049] The protective housing here refers to the protective housing 51 of the single-circuit heating device described in Patent Document 2.

[0050] Table 2 (Dual Circuit)

[0051] Specifications (kw) 500 600 800 1100 Winding temperature rise (k) 61.5 66.3 71.7 73.8 Protective shell temperature rise (k) 26.6 27.1 29.8 32.5

[0052] The protective shell refers to the protective shell 51 of the dual-circuit heating device in Application Example 2 of the present invention.

[0053] Winding temperature rise: resistance method detection, see national standard GB1094.2 Power Transformer Part 2, the enterprise standard temperature rise should not exceed the rated 75k.

[0054] Temperature rise of protective casing: Detected by surface point thermometer, the temperature rise should not exceed the rated 50K.

[0055] As shown in Table 1, the single-circuit heating device described in Patent Document 2 can operate satisfactorily up to 420 kW. Table 2 shows that, compared to Table 1, the winding temperature rise of the same specification has been significantly reduced, which is roughly consistent with the reduction in the dual-circuit surface heat load. Therefore, the winding temperature rise meets the rated requirements, and the protective housing temperature rise has been significantly reduced.

[0056] (Test Example 2)

[0057] A scaling comparison test was conducted on a single-circuit heating device described in Patent Document 2 and a three-phase power frequency dual-circuit electromagnetic induction and short-circuit heating device for liquid use manufactured by the present invention. Using the same hot water storage tank and heating water temperatures ranging from 45 to 90°C, the devices were returned to the factory for disassembly after 16 months of operation. The relevant data is shown in Table 3:

[0058] Table 3 (scaling test comparison)

[0059] Heating device Specifications (kw) cosφ Reactive power (KVAR) Visual inspection of scaling (secondary housing surface) Single circuit 1000 0.9805 38.7 Soft scale: light brown, the entire secondary shell is scarred and peeling Dual circuit 1000 0.9702 58.7 No scale: There is no trace of scale on the entire secondary shell

[0060] In Table 3, cosφ is the measured value, and the power is calculated based on the rated value, so that the output reactive power comparison is clearer. The experiment confirmed the positive effects (2) and (3) mentioned above.

[0061] In the present application, the basic structural method of the double circuit composed of the guide member 10 of the liquid three-phase industrial frequency double-circuit electromagnetic induction and short-circuit heating device and the second shell 4-2 is applied. A three-circuit or multi-circuit induction heating device with a larger single-unit capacity can be formed on the outside of the second shell 4-2. All of these are extensions of the present application and are within the scope of protection of the present application.

[0062] Although embodiments, application examples, and test examples of the present application have been shown and described herein, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to these technical solutions without departing from the principles and objectives of the present application. The scope of the present application is defined by the claims and their equivalents. For example, the description of "liquid" herein only refers to "water," but it can also be changed to "oil" or other liquid substances and still fall within the scope of protection of the present application.

Claims

1. A liquid-use three-phase power-frequency double-circuit electromagnetic induction and short-circuit heating device, comprising an EI-shaped core (1) entirely composed of laminated silicon steel sheets forming a closed three-phase magnetic circuit, a primary winding (2) wound around each of the three core legs of the EI-shaped core (1); characterized in that: The invention also has a metal shell, which includes a first loop metal shell and a second loop metal shell; the first loop metal shell is arranged along the three-phase closed magnetic circuit to form a secondary metal ring of each phase surrounding the iron core (1) and the primary winding (2) of each phase; the second loop metal shell is arranged along the outer side of the secondary side of each phase on the three core columns of the first loop iron core (1); thus, on the three core columns of the EI-shaped iron core (1), from the inside to the outside, the three-phase primary winding (2), the three secondary metal rings (Ua, Va, Wa) of the first loop short circuit, the three secondary metal rings (Ub, Vb, Wb) of the second loop short circuit, and the four secondary metal rings of each short circuit respectively surrounding the left and right parts of the upper and lower yokes of the iron core (1) are formed; thus, the metal shell forms a double-loop shell structure with 10 short-circuited secondary metal rings at the inner and outer two main heating elements of the core column of the iron core (1).

2. The liquid three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device according to claim 1 is characterized in that: The first circuit metal shell is composed of a first shell (4-1) and two rectangular tubes (5); the second circuit metal shell is composed of a second shell (4-2) and two flow guides (10) with folded fins at the front and rear ends; the height of the second shell (4-2) is higher than the height of the folded fins of the flow guide (10) and lower than the height of the first shell (4-1).

3. The liquid three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device according to claim 2 is characterized in that: The guide member (10) in the inner cavity of the rectangular tube (5) has its upper and lower surfaces welded to the upper and lower inner folded fins of the rectangular tube (5), and the straight portion of the guide member (10) is spaced the same as the inner wall of the rectangular tube (5) and is equal to the net height of the upper and lower inner folded fins of the rectangular tube (5); the front and rear folded fins of the guide member (10) extend out of the front and rear end surfaces of the rectangular tube (5) by a distance respectively, and are welded to the front and rear end surfaces of the rectangular tube (5).

4. The liquid three-phase power frequency double-circuit electromagnetic induction and short-circuit heating device according to claim 2 or 3, characterized in that: The rectangular tube (5) comprises a first rectangular tube (5a) and a second rectangular tube (5b), and the left and right sides of the first rectangular tube (5a) and the second rectangular tube (5b) respectively form three short-circuited secondary metal rings (Ua, Va, Wa) surrounding the primary windings (2) of each phase with the first shell (4-1); the flow guide (10) comprises a first flow guide (10a) and a second flow guide (10b), and the first flow guide (10a) and the second flow guide (10b) extend out of the corresponding first rectangular tube (5a) and the second rectangular tube. The front and rear end faces of (5b) are each separated by a distance, penetrate the front and rear faces of the second shell (4-2) and are welded and fixed, and the spacing around the second shell (4-2) and the first shell (4-1) is kept uniform; thereby, the left and right sides of the two said guide members (10) and the second shell (4-2) are respectively formed on the outside of the three short-circuited secondary metal rings (Ua, Va, Wa) of the first circuit, and are parallel to the three short-circuited secondary metal rings (Ub, Vb, Wb) of each primary winding (2) of the three phases to serve as the second main heating element.

Images