PFA heater high-temperature protection device and debugging method

Abstract

The invention relates to a PFA heater high-temperature protection device and a debugging method, and is characterized in that the PFA heater high-temperature protection device comprises a PFA heater and a resistance wire which is provided with a linear structure, an inlet and an outlet of liquid to be heated and is internally provided with a PFA shell; the heating element is provided with a heating section and a non-heating section, the heating section is located in the PFA heater and externally provided with a PFA protective shell, and the non-heating section is arranged outside the PFA heater and used for fixing the heating element; the thermocouple is arranged in the heating element and is used for measuring the temperature of the heating section; by adopting the high-temperature protection device, the problem that the resistance wire of the PFA shell cannot be directly installed on the high-temperature protection device can be solved, the damage of the heater is avoided, and by adopting the debugging method of the high-temperature protection device, the application scene of the high-temperature protection device is increased, and the universality is improved.

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 a debugging method thereof. Background Art

[0002] In the semiconductor industry, various acid liquids are usually heated. Since heated acid liquids are highly corrosive, in order to avoid corrosion of the resistance wire or the heating element by the acid liquid and to ensure the purity of the acid 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 will release gas as it heats up. When pure water is added, when the water flow suddenly stops, a 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 gas is inside, the resistance wire will dry burn in the gas and damage the FPA shell. Since the liquid cannot come into contact with the metal surface, it is only allowed to come into contact with fluoroplastics, which are difficult to process and conventional high-temperature protection devices are strictly prohibited. Therefore, damage to the acid heater and pure water heater often occurs.

[0004] For acid or pure water heating, a resistance wire with a PFA shell is usually used. Since the resistance wire uses a PFA shell, according to current technology, it is impossible to place the temperature sensor and the resistance wire in the PFA shell at the same time. Therefore, resistance wire high temperature protection is usually not used, but liquid high temperature protection is used, and the liquid temperature cannot represent the resistance wire temperature. In addition, the heater has a dry-burning condition. When there is gas inside the heater, or the liquid level is lower than the liquid high temperature protection thermocouple, or the PFA shell resistance wire is not completely immersed in the liquid, it will cause the PFA shell resistance wire to dry burn locally, causing the PFA to melt.

[0005] In addition, when the acid is heated, gas is also generated, causing the internal PFA shell resistance wire to be heated higher than 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 a 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 and an inlet and an outlet for the liquid to be heated, and having a built-in resistance wire with a PFA housing;

[0008] A heating element, wherein the heating element has a heating section and a non-heating section, wherein the heating section is located inside the PFA heater and is provided with a PFA protective shell, and the non-heating section is provided outside the PFA heater and is used to fix the heating element;

[0009] A thermocouple, which is arranged inside the heating element and measures 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 and 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 the outlet of the PFA heater may be located at one end of the linear structure at the same time or at two ends of the linear structure respectively.

[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 can regulate the power of the heating element by means of voltage regulation or by means of a micro solid-state relay.

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

[0018] Step 1: Measure and draw the PFA shell dry-burning temperature rise curve 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 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.

[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 temperature controller is set with the thermocouple high temperature protection setting value determined in step four, 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 compared with the prior art:

[0026] The PFA heater high temperature protection device of the present invention is provided with a heating element and a resistance wire, the heating element and the resistance wire are both wrapped with a PFA shell, and the heating element has a built-in thermocouple, and the temperature of the resistance wire PFA shell to be measured is indirectly measured by reading the temperature of the thermocouple by connecting the heating element and the resistance wire in series, thereby solving the problem of low liquid level alarm of the PFA heater and the problem that the high temperature protection device cannot be directly installed on the PFA shell;

[0027] The debugging method of the high temperature protection device of the PFA heater described in the present invention determines the protection temperature of the resistance wire PFA protection shell and the protection temperature of the thermocouple according to the definition of thermal conductivity by measuring the temperature of the resistance wire PFA protection shell, the temperature of the heating element PFA protection shell and the temperature of the thermocouple, thereby effectively solving the problem of dry burning of the heater PFA resistance wire and protecting the normal operation of the heater to the maximum extent. 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 according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

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

[0030] Figure 2 is the dry-burning 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 is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but 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 resistance wire 3 with a PFA shell built in. The liquid to be heated is usually an acidic liquid and ultrapure deionized water in the semiconductor industry. The liquid to be heated enters from the inlet of the PFA heater 1, flows through the resistance wire 3, and then flows out from the outlet after being heated. The resistance wire 3 has a PFA shell, which can effectively prevent the resistance wire 3 from being corroded by an acidic solution or contaminating the ultrapure deionized water.

[0037] A heating element 2, wherein the heating element 2 has a heating section 22 and a non-heating section 23, wherein the heating section 22 is located inside the PFA heater 1 and is provided with a PFA protective shell to prevent the metal shell of the heating element 2 from directly contacting the liquid to be heated, and the non-heating section 23 is provided outside the PFA heater 1 to fix the heating element 2;

[0038] Thermocouple 4 is arranged inside the heating element 1 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, and 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. According to the different heat flux density on the surface of the resistance wire, the heating speed of the resistance wire during dry burning in the air is also different. The larger the heat flux density, the faster the heating speed. The time required for dry burning to damage will be relatively short. Therefore, according to the different heat flux densities of the resistance wire, the diameter of the resistance wire and the wall thickness of PFA, according to actual measurements, the heating curve of the resistance wire 3 and the heating element 2 in the air and the time required to reach high temperature damage can be obtained. Therefore, the heating speed of the heating element PFA shell 21 can be adjusted so that its heating speed is greater than or equal to the actual measured heating speed of the resistance wire PFA shell 31. Since the heating element 2 is connected in series with the resistance wire 3, the resistance wire 3 and the heating element 2 are powered on and heated at the same time during dry burning. When the heating element shell PFA reaches the high temperature alarm temperature, the resistance wire PFA shell 31 will be lower than or equal to the alarm temperature. In this way, the high temperature damage of the resistance wire PFA shell 31 can be avoided, and the high temperature protection purpose of the resistance wire PFA shell 31 can be achieved.

[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 an insulating material to isolate the heating section 22 and the non-heating section 23. Magnesium oxide is an alkaline oxide, so it is arranged outside the PFA heater to avoid contact with the acidic solution. At the same time, magnesium oxide has a high melting point, is odorless, tasteless, and non-toxic, and can play a good flame retardant role when the PFA heater fails and burns dry. However, the present invention can select other insulating materials including but not limited to magnesium oxide powder.

[0042] In one embodiment of the present invention, the heating section 21 is shorter than the non-heating section 22. The heating section 21 is located inside the PFA heater and is not the main component for heating the liquid, but is an alternative solution for conveniently detecting the temperature of the resistance wire. Therefore, an excessively long heating section 21 is not required.

[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 at the same time or at both ends of the linear structure respectively, which may be specifically selected according to 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 can be used to observe the temperature of the thermocouple 4 and the temperature of the heating wire PFA shell 31 obtained after conversion at any time. The power adjustment device is used to adjust the power of the heating wire 3 and the heating element 2. When the power is changed, when the heating wire 3 is dry-burned, the heating element 2 reaches the high temperature alarm temperature first and disconnects the circuit, thereby playing a role of high temperature protection.

[0045] In one embodiment of the present invention, the power regulating device can 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 of the thermocouple 4 of the heating element 2 is sounded, the temperature field is a specific temperature field. At this time, the power of the heating element 2 is adjusted to a fixed value, the thermal conductivity of the material is a fixed value, and therefore the temperature difference is also a fixed value. Therefore, the temperature of the heating element thermocouple can indirectly represent the temperature of the PFA shell of the heating element, and the temperature difference between the thermocouple inside the heating element and its PFA shell is a fixed value.

[0047] refer to Figure 2For example, the high temperature protection temperature of the PFA shell 31 of the resistance wire is set to 120°C. At this time, the temperature of the PFA shell 21 of the heating element is measured, and the temperature is 147°C. At this time, the temperature of the built-in thermocouple 4 of the heating element 2 is 200°C. In other words, when the temperature of the thermocouple measuring point is 200°C, the temperature of the PFA shell of the resistance wire is 120°C. At this time, the high temperature alarm is activated to prevent the resistance wire from continuing to dry burn. If you need to increase the protection temperature of the PFA shell 31 of the resistance wire, you only need to adjust the high temperature protection value corresponding to 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 draw the PFA shell dry-burning temperature rise curve of the resistance wire. According to the design of the PFA heater, make the resistance wire and the PFA shell, install the temperature sensor on the PFA shell of the resistance wire, apply the rated voltage to the resistance wire, and dry-burn the resistance wire with the PFA shell in the air. The melting temperature of the PFA material is greater than 350°C. When the FPA shell temperature reaches 200°C, the heating can be stopped. Use a temperature recorder to record the temperature rise process of the PFA shell and draw the temperature rise curve.

[0053] Step 2: Determine the temperature rise curve and heating power of the PFA shell 21 of the heating element. Use a heating element with a built-in thermocouple 4. Install a PFA shell on the outside of the heating element 2. Fix a temperature sensor on the PFA shell. Connect the power to the heating element and record the temperature rise curves of the built-in thermocouple of the heating element and the PFA surface temperature sensor at the same time. By adjusting the voltage, the temperature rise rate of the PFA shell 21 of the heating element is exactly equal to the temperature rise rate of the PFA shell of the resistance wire measured in step 1. In this way, the temperature rise curve of the PFA shell 21 of the heating element and the temperature rise curve of the built-in thermocouple 4 can be obtained, and the power of the heating element at this time can be measured. This power is the rated power of the heating element used for high temperature protection. According to the rated voltage of the resistance wire and the determined power, this high temperature protection heating element is made.

[0054] Step 3: Determine the maximum operating temperature of the resistance wire PFA shell 31 in the liquid. According to the use requirements of the PFA heater 1, measure the maximum surface temperature of the resistance wire PFA shell when the PFA heater is operating normally. Also measure the maximum temperature of the resistance wire PFA shell when the liquid is heated to the required temperature when the liquid is stationary. The maximum value of the two maximum temperatures is the maximum operating temperature of the resistance wire FFA shell 31.

[0055] Step 4: Determine the high temperature protection setting value of the thermocouple. The highest temperature determined in step 3, multiplied by a safety factor of 1.2 to 1.5, is the protection temperature of the resistance wire PFA housing 31. According to the temperature curve drawn in step 2, find out the temperature of the thermocouple inside the heating element corresponding to this temperature. The temperature of the thermocouple inside this element is the high temperature protection setting value of the temperature controller.

[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 temperature controller is set with the thermocouple high temperature protection setting value determined in step four, 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 of step 4 is set on the temperature controller, the temperature controller is connected to the 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, the PFA shell of the resistance wire reaches the high-temperature protection temperature, the contactor is disconnected at this time, and the heater stops heating, avoiding damage to the heater. After the gas is discharged from the heater through exhaust, and the temperature of the heating element drops below the safe temperature, the heater is restarted.

[0059] By adopting the above steps and methods, a high temperature protection device of a PFA heater 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 heated liquids.

[0060] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still 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 and an inlet and an outlet for the liquid to be heated, and a resistance wire with a built-in PFA housing; A heating element, wherein the heating element has a heating section and a non-heating section, wherein the heating section is located inside the PFA heater and is provided with a PFA protective shell, and the non-heating section is provided outside the PFA heater and is used to fix the heating element; A thermocouple, which is arranged inside the heating element and measures the temperature of the heating section; The heating element and the resistance wire are connected in series.

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 the outlet of the PFA heater may be located at one end of the linear structure at the same time or at two ends of the linear structure respectively.

6. The PFA heater high temperature protection device according to claim 1, characterized in that: The PFA heater also 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 means of voltage regulation or by means of a micro solid-state relay.

8. A high temperature debugging method for a PFA heater, characterized in that: The PFA heater high temperature protection device according to any one of claims 1 to 7 comprises: Step 1: Measure and draw the PFA shell dry-burning temperature rise curve 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.

9. The high temperature debugging method of a PFA heater according to claim 8, 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.

10. The high temperature debugging method of a PFA heater according to claim 8, 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 temperature controller is set with the thermocouple high temperature protection setting value determined in step 4, the temperature controller signal is connected to the contactor, and the contactor is connected in series with the heating element.

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