High-purity helium oil cracking device

Abstract

The utility model provides a high-purity helium oil cracking device. The high-purity helium oil cracking device comprises a base, a shell, a filter element, an enrichment cavity, an electromagnetic coil, a thermocouple and a temperature controller, the base and the shell are made of high-thermal-conductivity red copper or aluminum materials and are in sealed connection through a limiting step, and a filter element with a multi-layer stainless steel micropore structure is vertically fixed in the base and the shell to form an enrichment cavity; the electromagnetic coil is uniformly wound on the outer wall of the cavity, and alternating current is dynamically adjusted by combining a high-heat-conduction material and a temperature controller, so that temperature uniformity and constant-temperature precision of the cavity are realized. Sample gas enters an enrichment cavity through a sealed pipeline, oil steam is captured by a filter element and then sequentially subjected to preheating dehydration, high-temperature cracking and photoacoustic spectrum detection, the oil content is reversely deduced through a calibration curve, and the detection resolution can reach ppb level. According to the device, through global induction heating, pressure difference control and closed-loop temperature control, the problems of non-uniform temperature and oil vapor migration of traditional single-end heating are solved, and the ultra-trace detection of trace oil in high-purity gas in the fields of semiconductors and spaceflight is met.

Description

Technical Field

[0001] This utility model relates to the field of gas analysis technology, specifically a high-purity helium oil cracking device based on overall electromagnetic heating, used to uniformly crack ppb-grade oil vapor into methane and perform quantitative detection. Background Technology

[0002] In modern industry, high-purity helium is a crucial industrial gas widely used in high-precision fields such as semiconductor manufacturing, superconducting equipment, and cryogenic refrigeration. However, high-purity helium often contains trace impurities such as water (H2O), nitrogen (N2), hydrocarbons (CxHy), and oil. Among these, the detection of trace oil vapor (ppb level) in high-purity helium is crucial for the stability of industrial equipment. When used as the working fluid in Gifford-McMahon (GM) refrigerators, its cold-end operating temperature can be as low as 4K or even lower. If the oil content exceeds the standard, oil vapor will condense and accumulate in the working fluid circulation pipeline, leading to increased flow resistance and reduced refrigeration efficiency, which can then cause serious equipment failure.

[0003] Currently, the common method for detecting trace oil vapor impurities in high-purity helium is the indirect measurement method of converting oil vapor into methane through cracking. Traditional cracking devices mostly use single-end resistance heating, which has problems such as large temperature gradient, pressure imbalance and low cracking efficiency. For example, 1. Single-end heating leads to an axial temperature difference of more than 50°C, and the temperature difference between the high-temperature zone and the low-temperature zone is extremely large. The residence time of oil vapor in the cracking zone is insufficient, which easily leads to incomplete cracking or over-cracking (causing coking); 2. Gas expansion in the high-temperature zone causes pressure imbalance, which will push uncracked oil vapor to diffuse to the low-temperature zone, resulting in a cracking loss of more than 30%; 3. Local thermal inertia differences may cause temperature fluctuations, resulting in insufficient cracking products (methane), making it difficult to meet the detection resolution requirements of ppb level. Utility Model Content

[0004] Therefore, this utility model provides a high-purity helium oil cracking device based on overall electromagnetic heating. The cracking chamber is directly heated by electromagnetic coils, and combined with flow control and temperature feedback, a gradient-free temperature field and dynamic pressure balance are achieved, thereby improving cracking resolution and detection accuracy.

[0005] This utility model provides a high-purity helium oil cracking device, mainly comprising: a base, a shell, a filter element, an enrichment cavity, an electromagnetic coil, a thermocouple, and a temperature controller. The base has an air inlet at its lower end and an air inlet pipe penetrating through the middle, with a first limiting step and a second limiting step symmetrically arranged at both ends. The shell is a hollow structure with an air outlet at its top and an air outlet pipe penetrating through the middle. The shell is sealed to the base via the first limiting step. The filter element is vertically fixed inside the shell and axially positioned to the base via the second limiting step. An enrichment cavity is formed between the filter element, the base, and the shell. The electromagnetic coil is evenly wound around the outer wall of the base and the shell to form a heating unit, with the number of coil turns evenly distributed. The thermocouple is in close contact with the outer wall of the filter element to monitor the temperature of the enrichment cavity. The temperature controller is connected to the thermocouple and the electromagnetic coil via signal lines. After receiving the temperature signal, it dynamically adjusts the frequency and amplitude of the alternating current of the electromagnetic coil to control the heating power of the enrichment cavity and achieve closed-loop temperature control.

[0006] Furthermore, one end of the inlet pipe is connected to the sample gas, and the other end is connected to the enrichment chamber. The outlet pipe is divided into two paths via a tee: the first outlet pipe is equipped with a first outlet valve and a first flow meter, and is connected to the methane analyzer; the second outlet pipe is equipped with a second outlet valve and a second flow meter, and is connected to the exhaust port. The inlet pipe, enrichment chamber, outlet pipe, and methane analyzer are sealed together, so that the sample gas to be tested flows through the inlet pipe and enrichment chamber in sequence for cracking reaction, and then enters the methane analyzer for detection through the first outlet pipe, while water vapor is discharged through the second outlet pipe.

[0007] Furthermore, the base and housing are made of copper or aluminum profiles or other materials with good thermal conductivity. When the electromagnetic coil is heated, the heat is radially diffused through the base and housing to the enrichment cavity, so as to achieve uniform heating of the cavity.

[0008] Furthermore, the filter element is made of multi-layer high-temperature sintered stainless steel wire mesh with a uniformly distributed microporous structure, which is used to capture oil vapor in the sample gas and achieve efficient enrichment.

[0009] Furthermore, the electromagnetic coils are designed with uniform distribution, and the base and housing are made of copper or aluminum profiles with high thermal conductivity to ensure consistent axial temperature of the cavity.

[0010] Furthermore, the temperature controller controls the induction heating intensity of the electromagnetic coil by adjusting the frequency and amplitude of the alternating current, thus solving the problem of excessive temperature gradient in traditional single-end heating.

[0011] The working process of the high-purity helium oil cracking device of this utility model is as follows:

[0012] 1. Enrichment stage: Open the inlet valve, close the first outlet valve and the second outlet valve. The sample gas (high-purity helium) enters the enrichment chamber through the inlet pipe and then the inlet valve is closed. The oil vapor in the sample gas is captured and enriched by the microporous structure of the filter element. The enrichment time and sample gas flow rate are controlled by preset parameters of the temperature controller.

[0013] 2. Preheating and dehydration: After enrichment, start the electromagnetic coil to heat to the set temperature and keep it at the set temperature for a preset time to completely vaporize the water in the enrichment chamber (during the enrichment stage, the water in the sample gas may condense at the microporous structure of the filter element due to the throttling cooling). After the temperature is kept constant, open the inlet valve and the second outlet valve, and use the second flow meter to control a certain sample gas flow rate to purge for several seconds to discharge the water (water vapor) enriched in the enrichment chamber through the exhaust port to ensure that the pyrolysis environment is water-free.

[0014] 3. High-temperature pyrolysis: After dehydration, the inlet valve and the second outlet valve are closed, and the electromagnetic coil continues to heat up to the pyrolysis temperature. The oil vapor in the enrichment chamber is pyrolyzed into gaseous hydrocarbons (CxHy) in an oxygen-free environment. The temperature controller maintains a constant temperature until the pyrolysis reaction is complete.

[0015] 4. Product Detection: After the pyrolysis process is completed, the inlet valve and the first outlet valve are opened, and a certain sample gas flow rate is controlled by the first flow meter to enter the enrichment chamber. The pyrolysis product (CxHy) is sent to the methane analyzer through the outlet pipe. After the methane concentration is measured based on the photoacoustic spectroscopy principle, the original total oil vapor content is deduced based on the pre-stored calibration curve of oil vapor concentration and methane response value (established by calibration with known oil vapor concentration). The detection resolution can reach the ppb level.

[0016] The beneficial effects of this invention are as follows: The device has a simple structure and directly heats the cavity through an integrated electromagnetic coil, eliminating the heat conduction delay of traditional resistance heating and achieving a temperature uniformity of 99.5%, thus completely solving the problem of local overheating or insufficient pyrolysis caused by single-end heating; the stainless steel microporous filter element in the enrichment cavity has an oil vapor capture efficiency of ≥99.9%, and combined with the overall heating design, the pressure difference in the cavity is <0.05kPa, eliminating oil vapor migration and achieving a pyrolysis stability of ±0.5%; the high-precision temperature control environment with balanced pressure significantly improves the pyrolysis efficiency, ultimately enabling the detection resolution of trace oil in high-purity helium to reach the ppb level, meeting the requirements of ultra-trace analysis. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the pyrolysis device of this utility model.

[0018] Figure 2 This is a cross-sectional view of the filter element of the pyrolysis device of this utility model.

[0019] Figure 3 This is a cross-sectional view of the base of the pyrolysis device of this utility model.

[0020] Figure 4 This is a cross-sectional view of the shell of the pyrolysis device of this utility model.

[0021] Symbol explanations in the diagram: 1. Base, 101. Air inlet, 102. Air inlet pipe, 103. Air inlet valve, 104. First limiting step, 105. Second limiting step, 2. Housing, 201. Air outlet, 202. Air outlet pipe, 3. Filter element, 4. Enrichment chamber, 5. Electromagnetic coil, 6. Thermocouple, 7. Temperature controller, 8. T-junction, 203. First air outlet pipe, 204. First air outlet valve, 205. First flow meter, 206. Second air outlet pipe, 207. Second air outlet valve, 208. Second flow meter, 9. Methane analyzer, 10. Exhaust port. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described herein are only some examples of this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.

[0023] like Figure 1-2 As shown, the present invention provides a high-purity helium oil cracking device, mainly comprising: a base 1, a shell 2, a filter element 3, an enrichment chamber 4, an electromagnetic coil 5, a thermocouple 6, and a temperature controller 7. The base 1 has an air inlet 101 at its lower end and an air inlet pipe 102 penetrating through the middle, and a first limiting step 104 and a second limiting step 105 symmetrically arranged at both ends. The shell 2 is a hollow structure, with an air outlet 201 at its top and an air outlet pipe 202 penetrating through the middle. The shell 2 is sealed to the base 1 through the first limiting step 104. The filter element 3 is vertically fixed to the shell. Inside the body 2, the filter element 3 is axially positioned with the base 1 via the second limiting step 105. An enrichment cavity 4 is formed between the filter element 3, the base 1, and the housing 2. The electromagnetic coil 5 is evenly wound around the outer wall of the base 1 and the housing 2 to form a heating unit. The number of coil turns is evenly distributed. The thermocouple 6 is in close contact with the outer wall of the filter element 3 to monitor the temperature of the enrichment cavity 4. The temperature controller 7 is connected to the thermocouple 6 and the electromagnetic coil 5 via signal lines. After receiving the temperature signal, it dynamically adjusts the frequency and amplitude of the alternating current of the electromagnetic coil 5 to control the heating power of the enrichment cavity 4 and achieve closed-loop temperature control.

[0024] The inlet pipe 102 and outlet pipe 202 are divided into two paths by a tee 8: the first outlet pipe 203 is equipped with a first outlet valve 204 and a first flow meter 205, and is connected to the methane analyzer 9; the second outlet pipe 206 is equipped with a second outlet valve 207 and a second flow meter 208, and is connected to the exhaust port 10; the inlet pipe 102, enrichment chamber 4, outlet pipe 202 and methane analyzer 9 are sealed together, so that the sample gas to be tested flows through the inlet pipe 102 and enrichment chamber 4 in sequence for cracking reaction, and then enters the methane analyzer 9 for detection through the first outlet pipe 203, and water vapor is discharged through the second outlet pipe 206. The sealed design of the entire pipeline ensures that the pressure difference is <0.05kPa.

[0025] The base 1 and the shell 2 are made of copper or aluminum profiles or other materials with good thermal conductivity. When the electromagnetic coil 5 is heated, the heat is radially diffused through the base 1 and the shell 2 to the enrichment cavity 4, so as to achieve uniform heating of the cavity.

[0026] Furthermore, the filter element 3 is made of multi-layer high-temperature sintered stainless steel wire mesh, with a uniformly distributed microporous structure, high filtration accuracy, and stable pores, which can effectively capture oil vapor in the sample gas and achieve efficient enrichment.

[0027] The electromagnetic coil 5 is evenly wound around the outer wall of the base 1 and the shell 2, and works in conjunction with the high thermal conductivity of the copper material to ensure that the axial temperature uniformity of the cavity reaches 99.5%.

[0028] The thermocouple 6 is attached to the outer wall of the filter element 3, monitors the temperature of the enrichment chamber 4 in real time and feeds it back to the temperature controller 7. The temperature controller 7 dynamically controls the heating power by adjusting the frequency (1-50kHz) and amplitude (0-100A) of the alternating current to achieve a constant temperature accuracy of ±0.3℃.

[0029] The working process of the pyrolysis device using high-purity helium as the sample gas provided by this utility model is as follows:

[0030] 1. Enrichment stage: Open the inlet valve 103, close the first outlet valve 204 and the second outlet valve 207. The sample gas (high-purity helium) enters the enrichment chamber 4 through the inlet pipe 102 and then the inlet valve 103 is closed. The oil vapor in the sample gas is captured and enriched by the microporous structure of the filter element 3. For trace oil detection, there is a corresponding calculation relationship between the enrichment time and the sample gas flow rate. If a flow rate of 18L / min is used, the enrichment time is 1118S. Under this flow rate and time, the total mass of the helium sample gas passing through the enrichment chamber is 150g.

[0031] 2. Preheating and dehydration: After enrichment, start the electromagnetic coil 5 and heat the enrichment chamber 4 to 110°C for 30 seconds. Then, keep the temperature constant for 30 seconds to completely vaporize the water in the enrichment chamber 4. After the temperature is constant, open the inlet valve 103 and the second outlet valve 207 and purge with sample gas at a rate of 1 L / min controlled by the second flow meter for 45 seconds. The water (water vapor) enriched in the enrichment chamber 4 is discharged through the exhaust port 10 to create an anhydrous environment for the subsequent pyrolysis reaction.

[0032] 3. High-temperature pyrolysis: After dehydration, the inlet valve 103 and the second outlet valve 207 are closed. The electromagnetic coil 5 continues to heat to the preset pyrolysis temperature (set according to the type of oil, such as 450℃ for mineral oil). After reaching the pyrolysis temperature, the oil vapor in the enrichment chamber 4 is pyrolyzed into gaseous hydrocarbons (CxHy) in an oxygen-free environment. At this time, the temperature is switched to constant temperature mode and kept constant for 60 seconds to ensure that the pyrolysis reaction is completed and to provide pure pyrolysis products for subsequent product detection.

[0033] 4. Product Detection: After the pyrolysis process is completed, the inlet valve 103 and the first outlet valve 204 are opened. The sample gas is controlled by the first flow meter 204 to enter the enrichment chamber 4 at a flow rate of 1 L / min. The pyrolysis product (CxHy) is sent to the methane analyzer 9 through the outlet pipe 202. The methane concentration is detected based on the photoacoustic spectroscopy principle. The original oil content is deduced by combining the pre-stored calibration curve of oil vapor concentration and methane response value. Standard oil vapor with a known concentration of 5-100 ppb is introduced into the device, and the output signal of the methane analyzer 9 is recorded. According to the formula: Methane concentration (ppb) = 0.98 * oil content (ppb) + 0.2 (R 2 =0.999), its detection resolution reaches 1ppb, and the error rate is ≤5%.

[0034] The design of this invention allows for precise control of the heating process and pyrolysis reaction, improving the efficiency of oil vapor pyrolysis and the accuracy of methane component detection in the measuring chamber.

[0035] The device achieves a stable pyrolysis environment with temperature uniformity ≥99.5% and pressure difference <0.05kPa through uniform heating by electromagnetic coil 5, high thermal conductivity materials, and closed-loop temperature control strategy. Combined with photoacoustic spectroscopy detection and calibration curves, it enables the detection resolution of trace oil in high-purity helium to reach the ppb level, meeting the ultra-trace analysis needs of the semiconductor and aerospace fields.

[0036] The foregoing description only illustrates certain exemplary embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high purity helium oil cracking unit, comprising essentially of: The base, the shell, the filter core, the enrichment cavity, the electromagnetic coil, the thermocouple and the temperature controller are characterized in that: the base is provided with an air inlet at the lower end and an air inlet pipe penetrating the middle part, and the first limiting step and the second limiting step are symmetrically arranged at both ends; the shell is a hollow structure, and is provided with an air outlet at the top and an air outlet pipe penetrating the middle part; the shell is sealingly connected with the base through the first limiting step; the filter core is vertically fixed in the shell and is axially positioned with the base through the second limiting step; the filter core, the base and the shell form the enrichment cavity; the electromagnetic coil is uniformly wound on the outer wall of the base and the shell to form a heating unit, and the number of turns of the coil is uniformly distributed; the thermocouple is closely attached to the outer wall of the filter core to monitor the temperature of the enrichment cavity; and the temperature controller is connected with the thermocouple and the electromagnetic coil through signal lines and dynamically adjusts the frequency and amplitude of the alternating current of the electromagnetic coil after receiving the temperature signal to realize closed-loop temperature control.

2. The high purity helium oil cracking device according to claim 1, characterized in that: One end of the air inlet pipe is in communication with the sample gas, and the other end is in communication with the enrichment cavity; the air outlet pipe is divided into two paths through a three-way pipe; the first path air outlet pipe is provided with a first air outlet valve and a first flowmeter and is connected with a methane analyzer; the second path air outlet pipe is provided with a second air outlet valve and a second flowmeter and is connected with an air outlet; and the air inlet pipe, the enrichment cavity, the air outlet pipe and the methane analyzer are sealingly connected, so that the measured sample gas flows through the air inlet pipe, the enrichment cavity for cracking reaction, and then enters the methane analyzer through the first path air pipe for detection, and the water vapor is discharged through the second path air pipe.

3. The high purity helium oil cracking device according to claim 1, characterized in that: The base and the shell are made of red copper or aluminum profile; when the electromagnetic coil is heated, the heat is radially diffused to the enrichment cavity through the base and the shell to realize uniform heating of the cavity.

4. The high purity helium oil cracking device of claim 1, wherein: The filter core is made of multiple layers of high-temperature sintered stainless steel wire mesh, and the microporous structure is uniformly distributed.

5. The high purity helium oil cracking device of claim 1, wherein: The electromagnetic coil is uniformly distributed, and cooperates with the high thermal conductivity of the base and the shell to ensure that the temperature of the cavity is uniform and consistent in the axial direction.

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