A PFA heater high temperature protection device and debugging method

Abstract

The present invention relates to a PFA heater high-temperature protection device and a debugging method, which are characterized by comprising: a PFA heater having a linear structure, an inlet and an outlet for a liquid to be heated, and a resistance wire with a built-in PFA shell; a heating element, the heating element having a heating section and a non-heating section, the heating section being located inside the PFA heater and externally provided with a PFA protective shell, the non-heating section being provided outside the PFA heater and used to fix the heating element; a thermocouple, the thermocouple being provided inside the heating element and measuring the temperature of the heating section; the heating element and the resistance wire being connected in series. By adopting this high-temperature protection device, the problem that the high-temperature protection device cannot be directly installed on the resistance wire of the PFA shell can be solved, thereby avoiding damage to the heater. By adopting this debugging method of the high-temperature protection device, the applicable scenarios of the high-temperature protection device are increased, and the universality is increased.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a PFA heater high temperature protection device and debugging method. Background Art

[0002] In the semiconductor industry, various acidic liquids are usually heated. Since heated acidic liquids are highly corrosive, in order to prevent the acidic liquid from corroding the resistance wire or heating element and to ensure the purity of the acidic liquid, corrosion-resistant PFA or PTFE is required as the outer shell of the resistance wire.

[0003] In addition, in the semiconductor industry, the water used for cleaning is mostly ultra-pure deionized water. In order to avoid contamination of pure water by the heating element, a resistance wire with a PFA shell is required. When the acid is heated, the acid releases gas as it heats up. When pure water is added, when the water flow suddenly stops, the large amount of heat inside the heater will melt, causing gas to be generated inside the heater. When the heater is powered on while the inside contains gas, the resistance wire will dry-burn in the gas and damage the FPA shell. Since liquids cannot come into contact with metal surfaces and are only allowed to come into contact with fluoroplastics, which are difficult to process, conventional high-temperature protection devices are strictly prohibited. Therefore, damage to acid heaters and pure water heaters is a common occurrence.

[0004] Acid or pure water heating typically uses a resistance wire with a PFA housing. However, due to the PFA housing, current technology prevents the simultaneous placement of a temperature sensor and the resistance wire within the PFA housing. Consequently, high-temperature protection using liquids is often employed, rather than the resistance wire itself. However, the liquid temperature does not represent the temperature of the resistance wire. Furthermore, heaters can dry-burn. If gas is present inside the heater, the liquid level falls below the liquid's high-temperature protection thermocouple, or the PFA-encased resistance wire is not fully submerged in the liquid, this can cause the PFA-encased resistance wire to partially dry-burn, leading to melting of the PFA.

[0005] In addition, when the acid is heated, gas is also generated, causing the internal PFA shell resistance wire to heat above the melting temperature of PFA, resulting in a decrease in the corrosion resistance of PFA. Summary of the Invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the problems of local dry burning of the PFA heater resistance wire and melting of the PFA shell in the prior art. Therefore, a PFA heater high-temperature protection device and debugging method are provided to solve the above technical problems. The present invention provides a PFA heater high-temperature protection device, comprising:

[0007] A PFA heater having a linear structure, an inlet and an outlet for the liquid to be heated, and a built-in resistance wire with a PFA housing;

[0008] A heating element, the heating element having a heating section and a non-heating section, the heating section being located inside the PFA heater and having a PFA protective shell outside, and the non-heating section being located outside the PFA heater and used to fix the heating element;

[0009] A thermocouple is provided inside the heating element to measure the temperature of the heating section;

[0010] The heating element and the resistance wire are connected in series.

[0011] In one embodiment of the present invention, the heating element is in the shape of a metal tube.

[0012] In one embodiment of the present invention, the heating element uses magnesium oxide powder as an insulating material to isolate the heating section from the non-heating section.

[0013] In one embodiment of the present invention, the heating section is shorter than the non-heating section.

[0014] In one embodiment of the present invention, the inlet and outlet of the PFA heater may be located at one end of the linear structure or at both ends of the linear structure.

[0015] In one embodiment of the present invention, the PFA heater further includes a temperature display device and a power adjustment device.

[0016] In one embodiment of the present invention, the power regulating device may regulate the power of the heating element by means of voltage regulation or by means of a micro solid-state relay.

[0017] To solve the above technical problems, the present invention further provides a debugging method using the above PFA heater high temperature protection device, comprising:

[0018] Step 1: Measure and draw the dry-heating temperature rise curve of the PFA shell of the resistance wire;

[0019] Step 2: Determine the temperature rise curve and heating power of the PFA shell of the heating element;

[0020] Step 3: Determine the maximum operating temperature of the PFA housing of the resistance wire in the liquid;

[0021] Step 4: Determine the thermocouple high temperature protection setting value;

[0022] Step 5: Install the high temperature protection interlock device.

[0023] In one embodiment of the present invention, a temperature recorder is used to record the temperature rise process of the PFA housing and draw a temperature rise curve, and a temperature sensor is used to fix the PFA housing to measure the temperature of the PFA housing.

[0024] In one embodiment of the present invention, the high-temperature protection interlocking device includes: a heating element with a built-in thermocouple, a temperature controller and a contactor, the thermocouple signal is connected to the temperature controller, the thermocouple high-temperature protection setting value determined in step four is set on the temperature controller, the temperature controller signal is connected to the contactor, and the contactor is connected in series with the heating element.

[0025] The above technical solution of the present invention has the following advantages over the prior art:

[0026] The PFA heater high-temperature protection device of the present invention comprises a heating element and a resistance wire, both of which are encased in a PFA housing. Furthermore, the heating element has a built-in thermocouple. By connecting the heating element and the resistance wire in series, the temperature of the PFA housing of the resistance wire to be measured is indirectly measured by reading the temperature of the thermocouple. This solves the problem of a low liquid level alarm in the PFA heater and the problem of being unable to directly install a high-temperature protection device on the PFA housing.

[0027] The debugging method of the high-temperature protection device of the PFA heater described in the present invention measures the temperature of the PFA protective shell of the resistance wire, the temperature of the PFA protective shell of the heating element, and the temperature of the thermocouple, and determines the protection temperature of the PFA protective shell of the resistance wire and the protection temperature of the thermocouple according to the definition of thermal conductivity. This effectively solves the problem of dry burning of the PFA resistance wire of the heater and maximizes the protection of the normal operation of the heater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

[0029] Figure 1 It is a structural schematic diagram of the high temperature protection device of the PFA heater of the present invention;

[0030] Figure 2 is the dry heating temperature rise curve of the PFA heater in the present invention;

[0031] Figure 3 It is a flow chart of the debugging steps of the PFA heater in the present invention.

[0032] Explanation of the reference numerals in the specification: 1. PFA heater; 2. Heating element; 21. PFA housing of heating element; 22. Heating section; 23. Non-heating section; 3. Resistance wire; 31. PFA housing of resistance wire; 4. Thermocouple. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0034] Example 1

[0035] Reference Figure 1 As described above, this embodiment provides a PFA heater high temperature protection device, comprising:

[0036] The PFA heater 1 has a linear structure and an inlet and an outlet for a liquid to be heated, and has a built-in resistance wire 3 with a PFA shell. The liquid to be heated is typically an acidic liquid or ultrapure deionized water in the semiconductor industry. The liquid to be heated enters the PFA heater 1 through the inlet, flows through the resistance wire 3, and then flows out through the outlet after being heated. The PFA shell of the resistance wire 3 effectively prevents the resistance wire 3 from being corroded by the acidic solution or contaminating the ultrapure deionized water.

[0037] A heating element 2, the heating element 2 having a heating section 22 and a non-heating section 23. The heating section 22 is located inside the PFA heater 1 and is protected by a PFA shell to prevent the metal shell of the heating element 2 from directly contacting the liquid to be heated. The non-heating section 23 is provided outside the PFA heater 1 to secure the heating element 2.

[0038] Thermocouple 4 is provided inside the heating element 2 to measure the temperature of the heating section 22. When the PFA shell 21 of the heating element reaches the high temperature damage temperature, the temperature of the thermocouple 4 inside the heating element 2 is read. This temperature is used as the alarm temperature of the PFA shell of the heating element.

[0039] The heating element 2 and the resistance wire 3 are connected in series. Depending on the surface heat flux density of the resistance wire, their temperature rise rates during dry heating in air also vary. A higher heat flux results in a faster temperature rise, and the time required for dry heating to damage is relatively short. Therefore, based on the resistance wire's different heat flux densities, wire diameter, and PFA wall thickness, actual measurements can be used to determine the temperature rise curves of the resistance wire 3 and heating element 2 in air, as well as the time required to reach high-temperature damage. Therefore, the temperature rise rate of the heating element PFA housing 21 can be adjusted to be greater than or equal to the measured temperature rise rate of the resistance wire PFA housing 31. Since the heating element 2 and the resistance wire 3 are connected in series, the resistance wire 3 and the heating element 2 are simultaneously powered and heated during dry heating. When the heating element PFA housing reaches the high-temperature alarm temperature, the resistance wire PFA housing 31 will be below or equal to the alarm temperature. This approach prevents high-temperature damage to the resistance wire PFA housing 31, achieving the desired high-temperature protection for the resistance wire PFA housing 31.

[0040] In one embodiment of the present invention, the heating element 2 is in the shape of a metal tube and simulates the diameter of the resistance wire and the wall thickness of the PFA shell, so that the variables affecting the temperature rise curves of the heating element 2 and the resistance wire 3 are reduced.

[0041] In one embodiment of the present invention, the heating element 2 uses magnesium oxide powder as the insulating material to separate the heating section 22 from the non-heating section 23. Magnesium oxide is an alkaline oxide and is therefore located outside the PFA heater to prevent contact with acidic solutions. Furthermore, magnesium oxide has a high melting point and is odorless, tasteless, and non-toxic, providing excellent flame retardancy in the event of a PFA heater failure and dry burning. However, other insulating materials, including but not limited to magnesium oxide powder, may be used in the present invention.

[0042] In one embodiment of the present invention, the heating section 22 is shorter than the non-heating section 23. The heating section 22 is located inside the PFA heater and is not the main component for heating the liquid. Instead, it serves as an alternative solution for conveniently detecting the temperature of the resistance wire. Therefore, there is no need for an overly long heating section 22.

[0043] In one embodiment of the present invention, the inlet and outlet of the PFA heater 1 may be located at one end of the linear structure or at both ends of the linear structure, and the selection may be made based on the principle of the PFA heater 1 .

[0044] In one embodiment of the present invention, the PFA heater 1 further includes a temperature display device and a power adjustment device. The temperature display device of the PFA heater 1 facilitates the observation of the temperature of the thermocouple 4 and the converted temperature of the heating wire PFA housing 21 at any time. The power adjustment device is used to adjust the power of the heating wire 3 and the heating element 2. The power is changed so that when the heating wire 3 is dry-burned, the heating element 2 reaches the high-temperature alarm temperature first and disconnects the circuit, thereby providing high-temperature protection.

[0045] In one embodiment of the present invention, the power regulating device may regulate the power of the heating element by means of voltage regulation or by means of a micro solid-state relay.

[0046] Specifically, according to the definition of thermal conductivity, when the high-temperature alarm is triggered by thermocouple 4 in heating element 2, the temperature field is a specific temperature field. At this time, the power of heating element 2 is adjusted to a constant value, and the thermal conductivity of the material is a constant, so the temperature difference is also a constant value. Therefore, the temperature of the heating element thermocouple can indirectly represent the temperature of the heating element's PFA casing. The temperature difference between the thermocouple inside the heating element and its PFA casing is a constant value.

[0047] refer to Figure 2For example, if the high-temperature protection temperature of the PFA housing 31 of the resistance wire is set to 120°C and the temperature of the PFA housing 21 of the heating element is measured at 147°C, the temperature of the thermocouple 4 built into the heating element 2 is 200°C. This means that if the temperature of the thermocouple measuring point is 200°C during a dry burn, the temperature of the PFA housing of the resistance wire is 120°C, triggering a high-temperature alarm to prevent further dry burn. If you need to increase the protection temperature of the PFA housing 31 of the resistance wire, simply adjust the corresponding high-temperature protection value of the thermocouple according to the curve.

[0048] When the liquid level just immerses the resistance wire 3 and the heating element is exposed to the gas, the heating element 2 will generate a high temperature alarm due to dry burning and will stop heating. It will continue heating after the gas is discharged.

[0049] By adopting this high-temperature protection device, the problem that the PFA shell resistance wire cannot be directly installed with the high-temperature protection device can be solved, thereby avoiding damage to the heater.

[0050] Example 2

[0051] refer to Figure 1 as well as Figure 2 The present invention also provides a debugging method using the above-mentioned PFA heater high temperature protection device, comprising:

[0052] Step 1: Measure and plot the dry-heating temperature curve of the PFA shell of the resistance wire. According to the design of the PFA heater, prepare the resistance wire and PFA shell. Install a temperature sensor in the PFA shell of the resistance wire. Apply a rated voltage to the resistance wire and dry-heat the resistance wire with the PFA shell in air. The melting temperature of the PFA material is greater than 350°C. Heating can be stopped when the PFA shell temperature reaches 200°C. Use a temperature recorder to record the temperature rise of the PFA shell and plot the temperature rise curve.

[0053] Step 2: Determine the heating curve and heating power of the PFA housing 21 of the heating element. Use a heating element with a built-in thermocouple 4. Install a PFA housing on the exterior of the heating element 2, and secure a temperature sensor to the PFA housing. Power the heating element while recording the heating curves of both the built-in thermocouple and the PFA surface temperature sensor. Adjust the voltage so that the heating rate of the PFA housing 21 of the heating element is exactly equal to the heating rate of the resistance wire PFA housing measured in Step 1. This generates the heating curves of the PFA housing 21 and the built-in thermocouple 4, and measures the heating power of the heating element at this point. This power is the rated power of the high-temperature protection heating element. This high-temperature protection heating element is manufactured based on the rated voltage of the resistance wire and the determined power.

[0054] Step 3: Determine the maximum operating temperature of the resistance wire PFA housing 31 in the liquid. According to the use requirements of the PFA heater 1, measure the maximum surface temperature of the resistance wire PFA housing when the PFA heater is operating normally. Also measure the maximum temperature of the resistance wire PFA housing when the liquid is at rest and the liquid is heated to the required temperature. The maximum of the two maximum temperatures is the maximum operating temperature of the resistance wire FPA housing 21.

[0055] Step 4: Determine the thermocouple's high-temperature protection setpoint. Multiply the highest temperature determined in Step 3 by a safety factor of 1.2 to 1.5 to obtain the protection temperature of the PFA housing 31 of the resistance wire. Based on the temperature curve drawn in Step 2, find the corresponding temperature of the thermocouple inside the heating element. This temperature is the temperature controller's high-temperature protection setpoint.

[0056] Step 5: Install the high temperature protection interlock device.

[0057] In one embodiment of the present invention, the high-temperature protection interlocking device includes: a heating element with a built-in thermocouple, a temperature controller and a contactor, the thermocouple signal is connected to the temperature controller, the thermocouple high-temperature protection setting value determined in step four is set on the temperature controller, the temperature controller signal is connected to the contactor, and the contactor is connected in series with the heating element.

[0058] Specifically, the built-in thermocouple 4 of the heating element 2 is connected to a high-temperature protection temperature controller. The high-temperature protection temperature value set in step 4 is set on the temperature controller. The temperature controller is connected to a contactor, and the power cord of the heater is connected to the contactor. When the built-in thermocouple of the heating element reaches the high-temperature protection set value, that is, when the PFA housing of the resistance wire reaches the high-temperature protection temperature, the contactor is disconnected, and the heater stops heating, thus preventing damage to the heater. After the gas inside the heater is discharged through exhaust and the temperature of the heating element drops below the safe temperature, the heater is restarted.

[0059] By using the above steps, high temperature protection devices of PFA heaters can be manufactured and installed for different types of PFA heaters. At the same time, different resistance wire PFA protection temperatures and thermocouple protection temperatures can also be selected according to different heating liquids.

[0060] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A PFA heater high temperature protection device, characterized in that, include: A PFA heater having a linear structure, an inlet and an outlet for the liquid to be heated, and a resistance wire with a built-in PFA housing; A heating element, the heating element having a heating section and a non-heating section, the heating section being located inside the PFA heater and having a PFA protective shell outside, and the non-heating section being located outside the PFA heater and used to fix the heating element; A thermocouple is provided inside the heating element to measure the temperature of the heating section; The heating element and the resistance wire are connected in series; The debugging method applied to the PFA heater high temperature protection device includes: Step 1: Measure and draw the dry-heating temperature rise curve of the PFA shell of the resistance wire; Step 2: Determine the temperature rise curve and heating power of the PFA shell of the heating element; Step 3: Determine the maximum operating temperature of the PFA housing of the resistance wire in the liquid; Step 4: Determine the thermocouple high temperature protection setting value; Step 5: Install the high temperature protection interlock device.

2. The PFA heater high temperature protection device according to claim 1, characterized in that: The heating element is in the shape of a metal tube.

3. The PFA heater high temperature protection device according to claim 2, characterized in that: The heating element uses magnesium oxide powder as an insulating material to isolate the heating section from the non-heating section.

4. The PFA heater high temperature protection device according to claim 1, characterized in that: The heating section is shorter than the non-heating section.

5. The PFA heater high temperature protection device according to claim 1, characterized in that: The inlet and outlet of the PFA heater may be located at one end of the linear structure or at both ends of the linear structure.

6. The PFA heater high temperature protection device according to claim 1, characterized in that: The PFA heater further includes a temperature display device and a power adjustment device.

7. The PFA heater high temperature protection device according to claim 6, characterized in that: The power regulating device can regulate the power of the heating element by adopting a voltage regulating method or a micro solid-state relay.

8. The PFA heater high temperature protection device according to claim 1, characterized in that: A temperature recorder is used to record the temperature rise process of the PFA shell and draw a temperature rise curve, and a temperature sensor is used to fix the PFA shell to measure the temperature of the PFA shell.

9. The PFA heater high temperature protection device according to claim 1, characterized in that: The high-temperature protection interlocking device includes: a heating element with a built-in thermocouple, a temperature controller and a contactor. The thermocouple signal is connected to the temperature controller. The thermocouple high-temperature protection setting value determined in step 4 is set on the temperature controller. The temperature controller signal is connected to the contactor, and the contactor is connected in series with the heating element.

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