An electric heater preheating system and method

Abstract

The present application relates to the technical fields of electric heater preheating, and particularly relates to an electric heater preheating system and method, comprising an electric heater and a preheating device. The electric heater comprises a shell, an electric heating tube and a junction box. The preheating device comprises a hot air module, a control module, a pressure sensor, a temperature and humidity sensor and a switch valve. The hot air module comprises a fan, a heating element and a connecting air pipe. The connecting air pipe is connected to a first pipe opening, so that the hot air generated by the hot air module is input into the shell through the first pipe opening. A second pipe opening is used for discharging air. The pressure sensor and the temperature and humidity sensor are arranged at the second pipe opening to detect the pressure value, the temperature value and the humidity value. The switch valve is arranged at the second pipe opening to adjust the opening and / or the opening degree of the second pipe opening. In the present application, the preheating device is connected to the electric heater to form a preheating system in the shutdown state of the electric heater. The preheating system does not need to rely on the energy of the molten salt system, and uses non-internal circulation air to realize the preheating and moisture removal of the electric heater.

Description

Technical Field

[0001] This invention relates to the field of electric heater preheating technology, and specifically to an electric heater preheating system and method. Background Technology

[0002] Molten salt thermal energy storage systems play a crucial role in the development of new energy fields, and the electric heater is the core equipment of such systems. Before starting a molten salt thermal energy storage system, if the electric heater has been stored for an extended period, it will be at room temperature, and moisture will accumulate inside. This makes it impossible to measure the insulation resistance of the electric heater in its hot state before use. Furthermore, if the molten salt thermal energy storage system is started directly under these conditions, the system temperature will be below the freezing point of the heat transfer medium, causing the medium to solidify. The resulting rapid temperature rise in the electric heater will lead to thermal stress concentration, affecting its lifespan. Additionally, the contact between moisture and molten salt increases the water content of the molten salt, potentially causing equipment corrosion, reduced thermal conductivity of the molten salt, and localized overheating or boiling of the molten salt.

[0003] Therefore, it is often necessary to preheat the electric heater, which has been stored for a long time, before starting the molten salt thermal storage system, in order to preheat and dehumidify the electric heater.

[0004] Currently, most existing preheating devices are integrated into molten salt thermal storage systems. They utilize the energy output of the molten salt system to produce hot air, which warms up the core equipment or pipelines of the system. After heat exchange, the hot air becomes cold air and is recycled back into the preheating device to reabsorb heat from the thermal storage system, thus creating a closed-loop air circuit. However, this design makes molten salt thermal storage systems relatively complex. When the molten salt system is operating normally, the pipeline valves of the preheating device must be closed; otherwise, there is a risk of leakage. Furthermore, its closed-loop nature means that it can only rely on the energy of the molten salt system and cannot preheat the system when the molten salt system is completely shut down. Summary of the Invention

[0005] To address the shortcomings of existing electric heater preheating solutions, this invention provides an electric heater preheating system and method. The system uses an external preheating device connected to the electric heater to form a preheating system. It utilizes non-internal circulating air to preheat and dehumidify the electric heater, enabling it to reach a preset temperature. This method does not rely on the energy of the molten salt system and can preheat and dehumidify the electric heater even when it is shut down.

[0006] The technical solution provided by this invention is as follows: an electric heater preheating system, comprising: an electric heater, the electric heater including a shell, an electric heating tube and a junction box, the electric heating tube extending from the junction box into the interior of the shell, the shell having a first port and a second port respectively at both ends, the first port being located above the shell and the second port being located below the shell; a preheating device, the preheating device including a hot air module, a control module, a pressure sensor, a temperature and humidity sensor and a switching valve, the control module being electrically connected to the hot air module, the pressure sensor and the temperature and humidity sensor, and the control module being used to supply power to the hot air module; the hot air module including a fan, a heating element and a connecting duct connected in sequence, the heating element being used to heat the air generated by the fan into hot air, the connecting duct being detachably connected to the first port so that the hot air generated by the hot air module is input into the shell through the first port; the second port being used to discharge air, the pressure sensor and the temperature and humidity sensor being located at the second port to detect pressure, temperature and humidity values, and the switching valve being located at the second port to adjust the opening and / or the opening degree of the second port.

[0007] Optionally, the control module includes a power supply unit and a control terminal. The control terminal is electrically connected to the temperature and humidity sensor, the pressure sensor, the hot air module, and the power supply unit. The power supply unit is electrically connected to the junction box so that the heating element receives power.

[0008] Optionally, the switching valve is a manual valve; or, the switching valve is an electric valve, and the switching valve is electrically connected to the control module.

[0009] Optionally, the preheating device further includes a base that supports the hot air module and the control module, and the base is provided with casters to make the base movable.

[0010] An electric heater preheating method, applied to an electric heater preheating system as described above, the method comprising: Start-up phase: The switch valve at the second port is closed, the control module supplies power to the hot air module, the fan and heating element of the hot air module start, and hot air is input into the housing of the electric heater through the connecting air duct and the first port to pressurize and exchange heat inside the housing and reduce the heating dead zone; the opening and closing of the switch valve or the opening degree are adjusted to ensure that the pressure inside the electric heater is less than the threshold pressure during pressurization and heat exchange; the temperature value of the second port is detected when the switch valve is open, and when the temperature and humidity sensor detects that the temperature value of the second port has reached 80°C, the switch valve is completely closed; Steady-state phase: The hot air module is continuously running. When the pressure sensor detects a pressure above 8 kPa, the switching valve is continuously or intermittently opened at a specific opening degree to release pressure, so that the pressure inside the electric heater is kept above 8 kPa but not higher than the threshold pressure. The temperature and humidity sensors are observed to ensure that the temperature inside the electric heater continues to rise and the humidity continues to decrease. Final stage: When the temperature and humidity sensor detects that the temperature has reached 280℃ and the humidity has dropped to a stable value, the control module automatically performs a PID temperature control program to dynamically adjust the power of the fan and heating element in the hot air module, so that the temperature of the second pipe port is maintained at the set value, and the electric heater preheating is completed.

[0011] Optionally, the startup phase further includes: the control module supplying power to the junction box, and the heating element starting up to assist in heating the air inside the heating element.

[0012] Optionally, during the start-up phase, when pressurized heat exchange occurs in the electric heater, the switching valve is adjusted to an opening of 10%–20%, and the fan outputs a wind pressure of 7 kPa–9 kPa; or the switching valve is fully opened, and the fan outputs a wind pressure of 4 kPa–6 kPa, so as to continuously input hot air into the electric heater and ensure that the pressure inside the electric heater is less than the threshold pressure during pressurized heat exchange.

[0013] Optionally, during the start-up phase, when the electric heater is pressurized and heat exchanged, the power of the fan and heating element in the hot air module remains constant, and hot air is continuously supplied to the electric heater. When the pressure sensor detects that the pressure reaches 5 kPa, the switching valve is intermittently opened or opened to a specific degree to ensure that the pressure inside the electric heater is less than the threshold pressure during pressurized heat exchange.

[0014] Optionally, during the startup phase, when the electric heater is pressurized and heat exchanged, the control module supplies power to the junction box, and the electric heating tube is activated to assist in heating the air inside the housing, thereby improving the efficiency of cold air exhaust.

[0015] Optionally, during the steady-state phase, the control module supplies power to the junction box, and the heating element is activated to assist in heating the air inside the housing so that the temperature inside the electric heater continues to rise.

[0016] Optionally, the threshold pressure is 2 MPa.

[0017] Compared with the prior art, the technical solution provided by this invention has the following advantages: In view of the defects of the existing electric heater preheating scheme, this invention can use a detachable preheating device to connect to the electric heater to form a preheating system when the electric heater is stopped. It does not rely on the energy of the molten salt system, and uses non-internal circulation air to preheat and dehumidify the electric heater, so that the electric heater reaches the preset temperature and ensures that the electric heater can be put into subsequent operation more reliably. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an electric heater preheating system proposed in an embodiment of the present invention. Detailed Implementation

[0019] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0020] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. The terms "first," "second," etc., used in this invention are for the convenience of describing the technical solutions of the invention and have no specific limiting effect; they are all general terms and do not constitute a limitation on the technical solutions of the invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contradict or conflict, all of which are within the scope of protection claimed by this invention.

[0021] Example 1 Combined with appendix Figure 1 This embodiment proposes an electric heater preheating system, including an electric heater 1 and a preheating device 2.

[0022] The electric heater 1 includes a housing 10, an electric heating tube 11, and a junction box 12. The electric heating tube 11 extends from the junction box 12 into the housing 10. The housing 10 has a first port 101 and a second port 102 at its two ends. The first port 101 is located above the housing 10, and the second port 102 is located below the housing 10.

[0023] The preheating device 2 includes a hot air module 21, a control module 22, a pressure sensor, a temperature and humidity sensor, and a switch valve 13. The control module 22 is electrically connected to the hot air module 21, the pressure sensor, and the temperature and humidity sensor, and the control module 22 is used to supply power to the hot air module 21.

[0024] The hot air module 21 includes a fan, a heating element and a connecting duct connected in sequence. The heating element is used to heat the air generated by the fan into hot air. The connecting duct is detachably connected to the first port 101 so that the hot air generated by the hot air module 21 is input into the housing 10 through the first port 101.

[0025] The second port 102 is used to discharge air. A pressure sensor and a temperature and humidity sensor are installed in the second port 102 to detect pressure, temperature and humidity values. A switching valve 13 is installed in the second port 102 to adjust the opening and / or opening degree of the second port 102.

[0026] The electric heater preheating system of this embodiment includes an electric heater 1 and an external preheating device 2. The electric heater 1 is a device in the molten salt energy storage system, and the preheating device 2 is an external device independent of the electric heater 1. The preheating device 2 can be detachably connected to the electric heater 1 through pipes and leads to flexibly form the electric heater preheating system. This preheating system does not rely on the energy of the molten salt system. The hot air module 21 in the preheating device 2 can introduce non-internal circulation hot air into the electric heater 1 when it is in a shutdown state to preheat and dehumidify the electric heater 1 module.

[0027] In this embodiment, the control module 22 further includes a power supply unit and a control terminal. The control terminal is electrically connected to the temperature and humidity sensor, the pressure sensor, the hot air module 21, and the power supply unit. The power supply unit can be electrically connected to the junction box 12 to provide power to the heating element 11. Therefore, based on the power supply unit, the control module 22 can not only supply power to the hot air module 21 but also connect to the junction box 12 of the electric heater 1 via a clamped power supply cable to provide 380V low-voltage electricity to the heating element 11 within the electric heater 1. Combined with the aforementioned method of using hot air for preheating and dehumidification, the electric heater preheating system can further utilize the heating element 11 of the electric heater 1 to assist in preheating and dehumidification.

[0028] Specifically, the structure of the electric heater preheating system in this embodiment is as follows: the outlet side of the hot air module 21 is connected to the first port 101 of the electric heater 1 via a connecting duct, and the second port 102 of the electric heater 1 is equipped with a temperature and humidity sensor, a pressure sensor, and a switching valve 13. The power supply unit of the control module 22 is connected to the junction boxes at both ends of the electric heater 1 via a power supply cable to supply power to the heating element 11 in the electric heater 1. The power supply cable has a high-current cable clamp at the end, making the connection simple and efficient, without the need to disassemble the power cord.

[0029] In this embodiment, the advantage of introducing hot air through the first port 101 located above the housing 10 is that hot air tends to rise. After entering the electric heater 1 through the first port 101, the hot air can first gather in the upper region of the electric heater 1, thereby suppressing the tendency of hot air to quickly leave the electric heater 1 through the second port 102, reducing the airflow short-circuiting phenomenon, increasing the residence time of hot air in the electric heater 1, and allowing the hot air to gradually diffuse from top to bottom. This design can reduce dead zones in the electric heater 1 and improve preheating uniformity, and also improve the heat exchange effect of hot air in the electric heater 1, thus improving the preheating effect of the electric heater 1.

[0030] In actual preheating work, if the heating element 11 is heated by low-voltage electricity supplied by the control module 22 without hot air is introduced, there is no medium around the heating element 11 to carry away the heat, which may cause the electric heater 1 to overheat. Therefore, in this embodiment, the electric heater preheating system uses hot air preheating as the main means and the self-heating of the heating element 11 as an auxiliary means to preheat the electric heater 1.

[0031] The switching valve 13 is used to control the airflow condition of the second port 102. Generally, the switching valve 13 can be a manual valve or an electric valve. In a preferred embodiment, when the switching valve 13 is an electric valve, the switching valve 13 is electrically connected to the control module 22. The control module 22 automatically controls the switching valve 13 based on the acquired data and its own program, which can reduce manual dependence and improve the level of automation. Generally, the control module 22 is a console containing a power supply unit, an interactive interface, and internal control circuitry, used to control the operation of the electric heater preheating system.

[0032] Furthermore, in a preferred embodiment, the preheating device 2 also includes a base 20, which supports the hot air module 21 and the control module 22, and the base 20 is provided with casters 201 to make the base 20 movable. Thus, the casters 201 provided at the bottom of the base 20 allow the preheating device 2 to move flexibly, so as to easily form an electric heater preheating system with different electric heaters 1.

[0033] Example 2 Combined with appendix Figure 1 This embodiment proposes a preheating method, which is applied to the electric heater preheating system described in the technical solution of Embodiment 1, to preheat the electric heater 1.

[0034] Specifically, the preheating method includes a start-up phase, a steady-state phase, and a termination phase. The preheating method will be explained in detail below.

[0035] First, it should be noted that the preheating schemes in the prior art mainly utilize the energy of the molten salt system and are only a part of the molten salt system. Therefore, the air in the system is internally circulated during hot air preheating. However, in the preheating system formed after the external preheating device 2 is connected in this embodiment, the air used for preheating is not internally circulated. Therefore, the original cold air in the electric heater 1 to be preheated does not participate in the preheating (a unique problem of the external preheating device 2). Instead, it will create a dead zone in the electric heater 1 due to its space occupation. Moreover, the cold air will absorb the heat of the hot air, causing the average temperature of the air in the electric heater 1 to drop significantly, resulting in a reduction in preheating efficiency.

[0036] Furthermore, when preheating begins, the electric heater 1 contains cold air. If the second port 102 of the electric heater 1 is open (i.e., the switch valve 13 is fully open), and the hot air has a certain power under the action of the fan, a short-circuit phenomenon of airflow is likely to occur. That is, the hot air entering the electric heater 1 travels directly toward the second port 102, resulting in more dead zones inside the electric heater 1.

[0037] Therefore, during the startup phase, the switch valve 13 at the second port 102 needs to be closed first. Then, the control module 22 supplies power to the hot air module 21, and the fan and heating element in the hot air module 21 start. The air discharged by the fan is heated by the heating element and enters the electric heater 1 through the connecting air duct from the first port 101 located above the housing 10. At this time, since the second port 102 is closed, the continuously input hot air gradually diffuses to all parts of the electric heater 1, so that the hot air is pressurized and heat-exchanged inside the housing 10 and the heating dead zone is reduced. The hot air transfers heat to all parts of the electric heater 1, achieving uniform preheating. During the above process, the switch valve 13 is completely closed to keep the second port 102 closed. The process of continuous diffusion of hot air is a process of pressurization and heat exchange within the electric heater 1.

[0038] Considering the presence of cold air inside the electric heater 1, if hot air is continuously supplied directly into the electric heater 1 without exhausting the air from the second port 102, it will obviously cause the internal pressure of the housing 10 to rise continuously and eventually exceed the bearing limit of its structure (such as housing 10, welds, seals, etc.), causing air pressure overload inside the electric heater 1, thereby causing equipment damage or safety accidents.

[0039] To avoid such pressure overload risks, corresponding preventive measures must be taken during the startup phase. In this embodiment, during pressurized heat exchange, the pressure inside the electric heater 1 is ensured to be less than the threshold pressure by adjusting the opening and closing of the switching valve 13. Generally, the preset pressure safety threshold pressure of the electric heater 1 is 2 MPa.

[0040] In conjunction with the aforementioned pressurization and heat exchange process, this preheating method is further designed in the startup phase as follows: when the switching valve 13 is opened, the temperature value of the second port 102 is detected. When the temperature and humidity sensor detects that the temperature value of the second port 102 has reached a stable 80°C, the switching valve 13 is completely closed, and the startup phase ends at this time.

[0041] In a preferred embodiment, during the startup phase, the control module 22 can supply power to the junction box 12, causing the heating element 11 to start and assist in heating the air inside the heating element. Referring to the aforementioned description of the startup phase, initially the second port 102 is closed, and the start-up of the heating element 11 allows the electric heater 1 to self-heat, thereby heating the original cold air to a certain extent. The heated cold air rises and joins the externally input hot air, together forming hot air that accumulates in the upper region of the electric heater 1, thus accelerating the downward diffusion of the hot air and improving the heating efficiency during the startup phase.

[0042] Furthermore, closing the switch valve 13 at the second port 102 at the beginning of the aforementioned start-up phase serves another purpose: to allow the hot air to remain in the electric heater 1 for a longer period of time. When the electric heater 1 self-heats, it can also reheat the hot air and spread the heat from the heating tube 11 to all parts of the electric heater 1, thereby improving the heating efficiency during the start-up phase.

[0043] Furthermore, as can be seen from the foregoing description, in order to avoid overload of the gas pressure inside the electric heater 1, the corresponding preventive measures taken during the start-up phase are as follows: during pressurized heat exchange, the pressure inside the electric heater 1 can be ensured to be less than the threshold pressure by adjusting the opening or closing of the switch valve 13.

[0044] Specifically, in a preferred embodiment, during the start-up phase, when the electric heater 1 is pressurized for heat exchange, the switch valve 13 is adjusted to an opening of 10%-20%, and the fan outputs a wind pressure of 7kPa-9kPa; or the switch valve 13 is fully opened, and the fan outputs a wind pressure of 4kPa-6kPa, so as to continuously input hot air into the electric heater 1 and ensure that the pressure inside the electric heater 1 is less than the threshold pressure during pressurized heat exchange.

[0045] Based on the characteristic that hot air enters from the first port 101 and first accumulates in the upper region of the housing 10 of the electric heater 1, this embodiment can gradually compress the cold air inside the electric heater 1 downwards and discharge it through the second port 102. This not only solves the problem of pressure overload inside the electric heater 1 and ensures safety, but also reduces the impact of cold air on preheating efficiency.

[0046] This implementation method achieves the effect of preventing hot air from being discharged while hot air is continuously input, so that hot air is evenly diffused to all parts of the electric heater 1, achieving preheating uniformity. It not only eliminates dead zones, but also improves the heat exchange efficiency between hot air and electric heater 1, thereby improving the preheating effect and efficiency.

[0047] This implementation method is generally not used in conjunction with the self-heating of the electric heater 1. The reason is that the hot air in the upper part of the electric heater 1 gradually pushes the cold air downwards and is discharged. The air in the electric heater 1 is in a circulating state, which makes it easy to carry away the heat from the heating element 11. However, when the air that has absorbed heat is quickly discharged from the second port 102, the cold air in the electric heater 1 may not be completely discharged, that is, the dead zone still exists. The temperature sensor at the second port 102 may mistakenly judge that the cold air has been completely discharged because the detected temperature value reaches the preset value. Therefore, in this implementation method, it is preferable that the self-heating of the electric heater 1 is not involved.

[0048] In another preferred embodiment, during the start-up phase, when the electric heater 1 is pressurized and heat exchanged, the power of the fan and heating element in the hot air module 21 remains constant, and hot air is continuously input into the electric heater 1. When the pressure sensor detects that the pressure reaches 5 kPa, the switch valve 13 is intermittently opened or the switch valve 13 is opened to a specific degree to release pressure and discharge some air, ensuring that the pressure in the electric heater 1 is less than the threshold pressure during pressurized heat exchange.

[0049] In this implementation, as hot air is continuously input, the cooled air inside the electric heater 1 is squeezed out, while the hot air is evenly diffused to all parts of the electric heater 1, achieving preheating uniformity. This eliminates dead zones and improves the heat exchange efficiency between the hot air and the electric heater 1, thereby enhancing the preheating effect and efficiency.

[0050] The advantage of this implementation method is that the hot air and cold air are mixed to reach a high pressure value first, and then the pressure is released to discharge the cooled air. Because the internal pressure is high, the rate of cold air discharge is high, which can improve efficiency.

[0051] Based on this preferred embodiment, the junction box 12 can also be powered simultaneously via the control module 22, causing the heating element 11 to start and assist in heating the air inside the housing 10, thereby improving the efficiency of cold air discharge. At this time, the electric heater 1 self-heats and intervenes, which can accelerate the heating and pressurization inside the electric heater 1, quickly increase the temperature level inside the electric heater 1, and quickly increase the pressure (to 5 kPa). Subsequently, during the depressurization process, the air is quickly discharged and the internal air is quickly heated, improving efficiency.

[0052] When the temperature and humidity sensor detects that the temperature value of the second port 102 has reached a stable 80°C, it indicates that the cold air has been completely discharged in the initial stage, and the hot air with a relatively uniform temperature has been evenly diffused inside the electric heater 1, so that the hot air and the electric heater 1 can exchange heat fully. At this time, the switch valve 13 can be closed, the start-up stage ends, and the steady state stage begins.

[0053] During the steady-state phase, the hot air module 21 is continuously activated. When the pressure sensor detects a pressure above 8 kPa, the switching valve 13 is continuously or intermittently opened at a specific opening degree to release pressure, so that the pressure inside the electric heater 1 is maintained above 8 kPa but not above the threshold pressure. The temperature and humidity sensors are observed to ensure that the temperature inside the electric heater 1 continues to rise and the humidity continues to decrease.

[0054] Clearly, in the steady-state phase, the electric heater 1 is entirely filled with hot air. Hot air is continuously input into the first port 101 and continuously discharged from the second port 102 (the temperature decreases after heat exchange). This means the entire preheating system maintains a steady flow of hot air, thus achieving continuous and stable preheating of the electric heater 1. Furthermore, with the stable input and output of hot air, the moisture inside the electric heater 1 can be effectively expelled, achieving dehumidification while preheating.

[0055] Furthermore, during the steady-state phase, the air inside the electric heater 1 maintains a steady flow, which can stably remove the heat from the heating element 11 and avoid the risk of overheating. Therefore, during the steady-state phase, it is preferable that the control module 22 supplies power to the junction box 12, and the heating element 11 is activated to assist in heating the air inside the housing 10 so that the temperature inside the electric heater 1 continues to rise. At this time, the self-heating of the electric heater 1 continues to intervene, and the hot air entering the electric heater 1 is reheated. The hot air is used as a medium to diffuse the heat to all parts of the electric heater 1, thereby improving the preheating efficiency and effect during the steady-state phase, as well as improving the dehumidification effect.

[0056] Finally, the process enters the final stage. When the temperature and humidity sensor reaches 280℃ and the humidity drops to a stable value, the control module 22 automatically executes the PID temperature control program, dynamically adjusting the power of the fan and heating element in the hot air module 21 to maintain the temperature of the second port 102 at the set value, thus completing the preheating of the electric heater 1. The PID temperature control program is a conventional temperature control program, and its control logic is as follows: comparing the difference between the set temperature and the actual temperature, and then dynamically adjusting the temperature by adjusting the power of the fan and heating element in the hot air module 21, and / or the opening degree of the switching valve 13, etc.

[0057] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. An electric heater preheating system, characterized in that, include: An electric heater (1) includes a housing (10), an electric heating tube (11), and a junction box (12). The electric heating tube (11) extends from the junction box (12) into the interior of the housing (10). The housing (10) has a first port (101) and a second port (102) at its two ends. The first port (101) is located above the housing (10), and the second port (102) is located below the housing (10). The preheating device (2) includes a hot air module (21), a control module (22), a pressure sensor, a temperature and humidity sensor, and a switch valve (13). The control module (22) is electrically connected to the hot air module (21), the pressure sensor, and the temperature and humidity sensor, and the control module (22) is used to supply power to the hot air module (21). The hot air module (21) includes a fan, a heating element and a connecting duct connected in sequence. The heating element is used to heat the air generated by the fan into hot air. The connecting duct is detachably connected to the first port (101) so that the hot air generated by the hot air module (21) is input into the housing (10) through the first port (101). The second port (102) is used to discharge air. The pressure sensor and the temperature and humidity sensor are located at the second port (102) to detect pressure, temperature and humidity values. The switch valve (13) is located at the second port (102) to adjust the opening and closing of the second port (102) and / or the opening degree.

2. The electric heater preheating system according to claim 1, characterized in that, The control module (22) includes a power supply unit and a control terminal. The control terminal is electrically connected to the temperature and humidity sensor, pressure sensor, hot air module (21) and power supply unit. The power supply unit is electrically connected to the junction box (12) so that the heating tube (11) can obtain power.

3. The electric heater preheating system according to claim 1, characterized in that, The switching valve (13) is a manual valve; or, the switching valve (13) is an electric valve, and the switching valve (13) is electrically connected to the control module (22).

4. The electric heater preheating system according to claim 1, characterized in that, The preheating device (2) also includes a base (20), which carries the hot air module (21) and the control module (22), and the base (20) is provided with casters (201) so that the base (20) can be moved.

5. A method for preheating an electric heater, characterized in that, Applied to an electric heater preheating system as described in any one of claims 1-4, the method comprises: Start-up phase: Close the switch valve (13) at the second port (102), the control module (22) supplies power to the hot air module (21), the fan and heating element of the hot air module (21) start, and hot air is input into the housing (10) of the electric heater (1) through the connecting air pipe and the first port (101) so that the hot air is pressurized and heat exchanged inside the housing (10) and the heating dead zone is reduced; and the pressure inside the electric heater (1) is less than the threshold pressure when the pressure is increased and heat exchanged by adjusting the opening or closing of the switch valve (13); when the switch valve (13) is open, the temperature value of the second port (102) is detected, and when the temperature and humidity sensor detects that the temperature value of the second port (102) has reached 80°C, the switch valve (13) is completely closed; Steady-state phase: The hot air module (21) is continuously started. When the pressure sensor detects that the pressure is above 8 kPa, the switch valve (13) is continuously opened or intermittently opened at a specific opening degree to release pressure so that the pressure inside the electric heater (1) is kept above 8 kPa but not above the threshold pressure. The temperature and humidity sensor is observed to ensure that the temperature inside the electric heater (1) continues to rise and the humidity continues to decrease. End stage: When the temperature and humidity sensor detects that the temperature reaches 280℃ and the humidity drops to a stable value, the control module (22) automatically performs the PID temperature control program, dynamically adjusts the power of the fan and heating element in the hot air module (21), so that the temperature of the second port (102) is maintained at the set value, and the electric heater (1) is preheated.

6. The electric heater preheating method according to claim 5, characterized in that, The startup phase also includes: the control module (22) supplies power to the junction box (12), and the heating element (11) is started to assist in heating the air inside the heating element.

7. The electric heater preheating method according to claim 5, characterized in that, During the start-up phase, when the electric heater (1) is pressurized for heat exchange, the switch valve (13) is adjusted to 10%-20% opening and the fan outputs a wind pressure of 7kPa-9kPa; or the switch valve (13) is fully opened and the fan outputs a wind pressure of 4kPa-6kPa, so as to continuously input hot air into the electric heater (1) and ensure that the pressure inside the electric heater (1) is less than the threshold pressure during the pressurized heat exchange.

8. The electric heater preheating method according to claim 5, characterized in that, During the start-up phase, when the electric heater (1) is pressurized and heat exchanged, the power of the fan and heating element in the hot air module (21) remains constant, and hot air is continuously input into the electric heater (1). When the pressure sensor detects that the pressure reaches 5 kPa, the switch valve (13) is opened intermittently or the switch valve (13) is opened to a specific degree to ensure that the pressure in the electric heater (1) is less than the threshold pressure during the pressurized heat exchange.

9. A preheating method for an electric heater according to claim 8, characterized in that, During the start-up phase, when the electric heater (1) is pressurized and heat exchanged, the control module (22) supplies power to the junction box (12), and the electric heating tube (11) is activated to assist in heating the air inside the housing (10) in order to improve the efficiency of cold air discharge.

10. A preheating method for an electric heater according to claim 5, characterized in that, During the steady-state phase, the control module (22) supplies power to the junction box (12), and the heating element (11) is activated to assist in heating the air inside the housing (10) so that the temperature inside the electric heater (1) continues to rise.

11. A preheating method for an electric heater according to claim 5, characterized in that, The threshold pressure is 2 MPa.

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