Float tin bath electric heating transformer design method

Abstract

The invention discloses a method for designing an electric heating transformer of a float tin bath. The method comprises the following steps: determining a working voltage gear of the transformer based on temperature and resistance change characteristics of a silicon carbide rod and rated voltage; determining the high-temperature-resistant grade of the transformer based on the environment temperature of the top of the tin bath; and determining the capacity of the transformer based on the sum of rated powers of the silicon carbide rods connected to the downstream of the transformer. According to the method for designing the electric heating transformer of the float tin bath, the working voltage gear is determined based on the temperature and resistance change characteristics of the silicon carbide rod, the design precision of the obtained working voltage gear of the transformer is high, and meanwhile the influence of environment temperature and spontaneous heating on working of the transformer is considered; and the tin bath electric heating transformer meeting the requirements can be quickly and accurately designed.

Description

Technical Field

[0001] The invention relates to the technical field of float tin bath design, and in particular to a design method of a float tin bath electric heating transformer. Background Art

[0002] In the production process of high-end electronic cover glass, the glass formula is different from other ordinary glasses, and the thickness is relatively thin, so the molding process of this type of glass in the tin bath requires precise control. The temperature of each area in the tin bath is one of the important factors affecting glass molding. Since the area at the outlet of the tin bath directly affects the hardening degree of the glass when it leaves the tin bath, if the temperature is too high, the hardness of the glass is not enough, and tin will contaminate the transition roller when it leaves the tin bath, resulting in a large number of glass scratches, especially in the production of ultra-thin high-end cover glass. This phenomenon is more obvious. Therefore, the temperature control requirements near the outlet of the tin bath are more stringent. The electric heating of the float tin bath generally adopts the mode of power regulator, transformer, internal electrical inside the hood, and silicon carbon rod for heating to provide an adjustable heat source for the inside of the tin bath. Among them, the transformer is a key device in the heating circuit, and its design method is very important. It must meet the large range of changes in the resistance value of the silicon carbon rod from cold to hot.

[0003] At present, for the design of transformers for electric heating of float tin baths, a design method with a large margin is generally adopted, and the design accuracy is poor. Therefore, seeking a transformer design method that can meet the complex environment of electric heating of float tin baths to solve the current technical problem of poor design accuracy of electric heating transformers for float tin baths has become a technical problem that needs to be urgently solved by technical personnel in this field.

[0004] Based on this, the existing technology still needs to be improved. Summary of the invention

[0005] In order to solve the above technical problems, an embodiment of the present invention proposes a design method for an electric heating transformer for a float tin bath, so as to solve the technical problems existing in the design of an electric heating transformer for a float tin bath in the prior art.

[0006] In order to solve the above technical problems, some embodiments of the present invention disclose a method for designing a float tin bath electric heating transformer, comprising: Determine the working voltage level of the transformer based on the temperature and resistance variation characteristics of the silicon carbon rod and the rated voltage; Determine the high temperature resistance level of the transformer based on the ambient temperature at the top of the tin bath; The capacity of the transformer is determined based on the sum of the rated powers of the silicon carbon rods connected downstream of the transformer.

[0007] In some embodiments, the temperature and resistance variation characteristics of the silicon carbon rod satisfy the formula: R t =R0×K1×(T0 / t) 2 t≤T0 R t =R0×K2×(t / T0) 2 t>T0 Among them, R t is the resistance value at the current temperature; R0 is the minimum resistance value of the silicon carbon rod; T0 is the temperature at which the silicon carbon rod has the minimum resistance value; t is the current temperature; K1, K2 are empirical coefficients.

[0008] In some embodiments, K1 takes a value of 1 and K2 takes a value of 2.

[0009] In some embodiments, determining the operating voltage level of the transformer based on the temperature and resistance variation characteristics of the silicon carbon rod and the rated voltage includes: The calculation formula for the highest voltage level on the secondary side of the transformer is: V=k×U; k=1.7~4; in, V is the highest voltage level on the secondary side of the transformer. U is the rated voltage of the silicon carbon rod.

[0010] In some embodiments, the number of gears of the transformer increases as the maximum voltage gear of the secondary side of the transformer increases.

[0011] In some embodiments, k is equal to 2.

[0012] In some embodiments, determining the high temperature resistance level of the transformer based on the ambient temperature at the top of the tin bath includes: The insulation grade of the transformer shall not be lower than the sum of the maximum ambient temperature of the tin bath and the maximum temperature rise of the insulating material.

[0013] In some embodiments, determining the capacity of the transformer based on the sum of the rated powers of the silicon carbon rods connected downstream of the transformer includes: The capacity of the transformer satisfies the formula: T=n×P Wherein, T is the transformer capacity; P is the sum of the rated powers of the silicon carbon rods connected to the transformer; and n is the amplification factor.

[0014] In some embodiments, n is in the range of 1.25-1.5.

[0015] In some embodiments, determining the operating voltage level of the transformer based on the temperature and resistance variation characteristics of the silicon carbon rod and the rated voltage includes: The voltage difference of the transformer tap position is between 7V-35V.

[0016] By adopting the above technical solution, the present invention has at least the following beneficial effects: The invention provides a float tin bath electric heating transformer design method, which determines the working voltage gear based on the temperature and resistance change characteristics of the silicon carbon rod, and the obtained transformer working voltage gear design has high precision. Meanwhile, the influence of the ambient temperature and self-heating on the operation of the transformer is considered, and a tin bath electric heating transformer that meets the requirements can be designed quickly and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the electric heating composition of the tin bath disclosed in some embodiments of the present invention; Figure 2 A schematic diagram of a transformer design disclosed in some embodiments of the present invention; Figure 3 Schematic diagram of resistance and temperature variation curve of silicon carbon rod disclosed in some embodiments of the present invention.

[0019] Description of reference numerals: 1. Power regulator; 2. Transformer; 3. Electrical inside the cover; 4. Silicon carbon rod; 21. Primary side coil; 22. Iron core; 23. First tap; 24. Second tap; 25. Third tap. DETAILED DESCRIPTION

[0020] The following is a further detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0021] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0022] It should be noted that, in the description of the present disclosure, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present disclosure 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 cannot be understood as a limitation of the present disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0023] In addition, the words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0024] It should also be noted that in the description of the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0025] All terms used in the present disclosure have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0026] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0027] like Figure 1 As shown, the electric heating of the float tin bath generally adopts the mode of power regulator 1, transformer 2, internal electric 3 and silicon carbon rod 4 for heating, providing an adjustable heat source for the inside of the tin bath. The design of the transformer 2 is as follows Figure 2As shown, it includes a primary side coil 21, an iron core 22, and multiple secondary side taps. There are three secondary side taps in the figure, namely a first tap 23, a second tap 24 and a third tap 25, which provide electrical energy for the silicon carbon rods. Since the insulation level of the transformer is closely related to the ambient temperature at the top of the tin bath, and at the same time, the change in the resistance value of the silicon carbon rod will cause the heat generated by it to fail to meet the requirements of the temperature field inside the tin bath, it is necessary to increase the output voltage of the secondary side of the transformer so that the heat generated by the silicon carbon rod can meet the temperature control range of production.

[0028] Therefore, when designing the electric heating transformer for the float tin bath, many factors need to be considered. Among them, the power regulator provides variable power electric energy to meet the regulation of the temperature field inside the tin bath; the transformer usually adopts a dry-type isolation transformer to convert high voltage into low voltage. Due to the long-term use of silicon carbon rods, the resistance of silicon carbon rods increases, and the heat generated cannot meet the requirements of the temperature field inside the tin bath. It is necessary to increase the output voltage of the secondary side of the transformer so that the silicon carbon rods can generate more heat; the internal electrical device is an energized connection device installed inside the large tin bath cover, which mainly transmits electrical energy; the silicon carbon rods generate heat by heating with electricity to meet the requirements of the temperature field inside the tin bath.

[0029] Some embodiments of the present invention disclose a design method for a float tin bath electric heating transformer, which determines the working voltage gear of the transformer based on the temperature and resistance change characteristics of the silicon carbon rod and the rated voltage; determines the high temperature resistance grade of the transformer based on the ambient temperature at the top of the tin bath; and determines the capacity of the transformer based on the sum of the rated powers of the silicon carbon rods connected downstream of the transformer. This embodiment determines the working voltage gear based on the temperature and resistance change characteristics of the silicon carbon rod, and the obtained transformer working voltage gear design accuracy is high. At the same time, considering the influence of ambient temperature and self-heating on the operation of the transformer, a transformer for electric heating of the tin bath that meets the requirements can be quickly and accurately designed.

[0030] In the design method of the electric heating transformer for the float tin bath disclosed in some embodiments of the present invention, based on the above embodiments, the temperature and resistance variation characteristics of the silicon carbon rod should satisfy the formula: R t =R0×K1×(T0 / t) 2 t≤T0 R t =R0×K2×(t / T0) 2 t>T0 Among them, R t is the resistance value at the current temperature; R0 is the minimum resistance value of the silicon carbon rod; T0 is the temperature at which the silicon carbon rod has the minimum resistance value; t is the current temperature; K1 and K2 are empirical coefficients. In some embodiments, K1 is 1 and K2 is 2. The temperature and resistance change characteristic formula of the silicon carbon rod provides accurate data support for determining the working voltage gear of the transformer, making the setting of the working voltage gear of the transformer more accurate, which is conducive to improving economic benefits.

[0031] In the above embodiment, on the basis of determining the temperature and resistance change characteristics of the silicon carbon rod, the working voltage level of the transformer is determined based on the temperature and resistance change characteristics of the silicon carbon rod and the rated voltage, and the rated voltage of the silicon carbon rod needs to be considered. Therefore, determining the working voltage level of the transformer based on the temperature and resistance change characteristics of the silicon carbon rod and the rated voltage should also include: The calculation formula for the highest voltage level on the secondary side of the transformer is: V=k×U; k=1.7~4, in some preferred embodiments, k can be 2; in, V is the highest voltage level on the secondary side of the transformer. U is the rated voltage of the silicon carbon rod.

[0032] Thus, the highest voltage level on the secondary side of the transformer can be determined, and then the number of transformer levels can be determined based on the highest voltage level on the secondary side of the transformer. Generally, the number of transformer levels increases with the increase of the highest voltage level on the secondary side of the transformer. It should be noted that the voltage difference of the transformer tap level should be between 7V and 35V.

[0033] In the design method of the electric heating transformer for the float tin bath disclosed in some embodiments of the present invention, based on the above embodiments, since the insulation level of the transformer is closely related to the temperature environment at the top of the tin bath, the insulation level of the designed transformer should be no lower than the maximum ambient temperature of the tin bath + the maximum temperature rise temperature of the insulating material. Therefore, determining the high temperature resistance level of the transformer based on the ambient temperature at the top of the tin bath includes: the insulation level of the transformer is no lower than the sum of the maximum ambient temperature of the tin bath and the maximum temperature rise temperature of the insulating material.

[0034] The float tin bath electric heating transformer design method disclosed in some embodiments of the present invention, based on the above embodiments, determines the capacity of the transformer based on the sum of the rated powers of the silicon carbon rods connected downstream of the transformer, including: the capacity of the transformer satisfies the formula: T=n×P Among them, T is the transformer capacity; P is the sum of the rated powers of the silicon carbon rods connected to the transformer; n is the amplification factor. In other words, the transformer capacity should not be less than the sum of the power of the silicon carbon rods in one partition × the factor, and the factor can be 1.25-1.5, that is, the value range of n is 1.25-1.5.

[0035] The design method of the float tin bath electric heating transformer disclosed in some embodiments of the present invention first needs to determine the working voltage level of the transformer based on the resistance change characteristics of the silicon carbon rod and the rated voltage. Silicon carbon rod manufacturers generally provide the rated resistance and current values ​​of the silicon carbon rods, and the rated voltage U is calculated by the formula U=IR. Figure 3 , the calculation formula for the highest voltage level on the secondary side of the transformer is as follows: V=k×UK Value range: 1.7-4 The larger the maximum voltage level V, the more levels are needed, and the higher the transformer cost. In addition, the voltage level on the secondary side of the transformer should take into account the aging of the silicon carbon rod. Good quality silicon carbon rods have a long service life and the resistance change can be controlled within 2 times, then K=2. On the contrary, if the resistance changes greatly, the cost issue cannot be considered when designing the transformer, and the process needs should be met first.

[0036] Secondly, the transformer design should meet the requirements of long-term high-temperature environment use. In float glass production, the ambient temperature at the top of the tin bath is generally 40℃-80℃, which is extremely inconvenient to repair and replace. The maximum ambient temperature at the top of the tin bath must be considered when designing the transformer, so a transformer with a high temperature resistance grade and suitable should be selected, F grade: maximum 155℃, H grade: maximum temperature 180℃, C grade: maximum temperature 220℃.

[0037] For transformer capacity design, the tin bath electric heating transformer is generally installed on the steel structure at the top of the tin bath, which has high temperature, limited space and is not easy to maintain. Therefore, the designed transformer can operate stably for a long time. Whether the transformer can operate for a long time depends on the transformer capacity. During the transformer power-on process, the coil and the core will generate heat, causing the transformer temperature to rise. Especially when the transformer is operated at full load or overload for a long time, the transformer will heat up sharply. When the temperature exceeds the heat resistance level, the insulation layer will be damaged and a short circuit accident will occur. Therefore, the transformer capacity should follow the following formula: Transformer capacity T = n × P Among them, P is the total rated power of the silicon carbon rods connected under the transformer, and n is the amplification factor (value range: 1.25-1.5).

[0038] Example In the production of a 0.5mm ultra-thin glass, the highest temperature at the top of the tin bath is 75℃. Based on this, the transformer insulation level is selected as H level, the sum of the rated power of the silicon carbon rods in the electric heating zone is P=120KW, the transformer coefficient n=1.4, the transformer capacity T=120×1.4=168KVA, 168KVA is closest to 160KVA, so the transformer capacity is selected as 160KVA. The rated voltage of the silicon carbon rods in the electric heating zone is 60V, then the highest voltage level V=1.73×60=104 (V), and 2 levels can be designed between 60~104: 75V and 90V. The secondary side of the transformer has 4 voltage levels, namely: 60, 75, 90, and 104.

[0039] In summary, the float tin bath electric heating transformer design method disclosed in the embodiment of the present invention determines the working voltage level of the transformer according to the resistance change characteristics of the silicon carbon rod and the rated voltage, which can meet the use requirements of long-term high-temperature environment. At the same time, the transformer capacity design fully considers the ambient temperature at the top of the tin bath and the temperature rise under the operating state. The whole design process is simple and reliable, and a tin bath electric heating transformer that meets the requirements can be designed quickly and accurately, which can effectively reduce the economic benefit loss caused by the transformer design, and has a good market application prospect.

[0040] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0041] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A float tin bath electric heating transformer design method, characterized in that: include: Determine the working voltage level of the transformer based on the temperature and resistance variation characteristics of the silicon carbon rod and the rated voltage; Determine the high temperature resistance level of the transformer based on the ambient temperature at the top of the tin bath; The capacity of the transformer is determined based on the sum of the rated powers of the silicon carbon rods connected downstream of the transformer.

2. The float tin bath electric heating transformer design method according to claim 1, characterized in that: The temperature and resistance variation characteristics of the silicon carbon rod satisfy the formula: R t =R0×K1×(T0 / t) 2 t≤T0 R t =R0×K2×(t / T0) 2 t>T0 Among them, R t is the resistance value at the current temperature; R0 is the minimum resistance value of the silicon carbon rod; T0 is the temperature at which the silicon carbon rod has the minimum resistance value; t is the current temperature; K1, K2 are empirical coefficients.

3. The float tin bath electric heating transformer design method according to claim 2, characterized in that: The value of K1 is 1, and the value of K2 is 2.

4. The float tin bath electric heating transformer design method according to claim 1, characterized in that: The working voltage range of the transformer is determined based on the temperature and resistance change characteristics of the silicon carbon rod and the rated voltage, including: The calculation formula for the highest voltage level on the secondary side of the transformer is: V=k×U; k=1.7~4; in, V is the highest voltage level on the secondary side of the transformer. U is the rated voltage of the silicon carbon rod.

5. The float tin bath electric heating transformer design method according to claim 4, characterized in that: The number of transformer gears increases with the increase of the highest voltage gear on the secondary side of the transformer.

6. The float tin bath electric heating transformer design method according to claim 4, characterized in that: The value of k is 2.

7. The float tin bath electric heating transformer design method according to claim 1, characterized in that: The high temperature resistance level of the transformer is determined based on the ambient temperature at the top of the tin bath, including: The insulation grade of the transformer shall not be lower than the sum of the maximum ambient temperature of the tin bath and the maximum temperature rise of the insulating material.

8. The float tin bath electric heating transformer design method according to claim 1, characterized in that: The capacity of the transformer is determined based on the sum of the rated powers of the silicon carbon rods connected downstream of the transformer, including: The capacity of the transformer satisfies the formula: T=n×P Wherein, T is the transformer capacity; P is the sum of the rated powers of the silicon carbon rods connected to the transformer; and n is the amplification factor.

9. The float tin bath electric heating transformer design method according to claim 8, characterized in that: The value range of n is 1.25-1.

5.

10. The float tin bath electric heating transformer design method according to claim 1, characterized in that: The working voltage range of the transformer is determined based on the temperature and resistance change characteristics of the silicon carbon rod and the rated voltage, including: The voltage difference of the transformer tap position is between 7V-35V.

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