AC arc discharge gas heating system

Abstract

An alternating-current arc discharge gas heating system relates to the field of arc plasma heating and comprises an alternating-current arc heating assembly, a first mixing chamber, a second mixing chamber, a spray pipe, a power supply system, a test system, a control system, a water cooling system and a gas supply system. And mounting support is provided for the alternating-current arc heating assembly. The gas supply system provides a gas medium for the alternating-current arc heating assembly, the first mixing chamber and the second mixing chamber; the water cooling system provides cooling water for the alternating-current arc heating assembly, the magnet exciting coil, the first mixing chamber, the second mixing chamber and the spray pipe. Most of gas can be subjected to arc heating through the alternating-current arc discharge device, supersonic high-temperature airflow with a certain enthalpy value is obtained, meanwhile, low ablation of an alternating-current arc discharge electrode is achieved through the phase displacement control technology, pollution of electrode ablation copper ions to the airflow is reduced, and the service life of the electrode is prolonged. Meanwhile, systematic safe and stable control in the running process of the heater is achieved, and accidents are avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of arc plasma heating and relates to an AC arc discharge gas heating system. Background Art

[0002] An arc heating system uses a high-temperature arc to heat gas, which is then accelerated through a nozzle to create a high-temperature, high-velocity airflow environment. This system is used for arc heating tests for aircraft thermal protection. The arc heating system employs arc discharge to heat the gas, creating a high-temperature, high-velocity flow field for testing. The arc heater's operational stability and the quality of the test gas flow field significantly impact the ability of the test to simulate realistic flight conditions and improve the precision of the test. Arc heating systems also have extensive industrial applications. Arc heating of the gas can provide high-temperature plasma flows for a variety of applications, including power generation, environmental protection, metallurgy, and chemical engineering. Arc discharge can be either direct current (DC) or alternating current (AC). DC single-arc discharge uses the workpiece as the electrode, resulting in low electrode loss and high heating efficiency, but also low power and an uneven heating field. DC dual-arc or multi-arc discharge uses an asymmetric cathode and anode, resulting in excessive loss in a single electrode, which can lead to electrode ablation and contamination of the high-temperature gas jet.

[0003] Currently, arc heaters suffer from the following drawbacks: significant localized electrode burnout, a short service life, low reliability, and a high failure rate under high-power, long-duration conditions. This often results in tests being terminated due to arc heater failures, and even in the scrapping of models. AC arc discharge, due to its reduced electrode erosion and highly efficient electrical-to-heat conversion, offers greater industrial application value than DC arc plasma. Therefore, AC arc plasma can theoretically address all areas where DC arc plasma is currently used. Summary of the Invention

[0004] The technical problem solved by the present application is: to overcome the shortcomings of the existing technology and provide an AC arc discharge gas heating system, which can reduce the loss of heater electrodes, make the system operation safer and more reliable, and make the high-temperature airflow parameters adjustable for different application scenarios.

[0005] The technical solutions provided in this application are as follows:

[0006] An AC arc discharge gas heating system, comprising:

[0007] a first mixing chamber;

[0008] An AC arc heating assembly includes a plurality of arc discharge chambers, each arc discharge chamber including a tubular rear electrode, a first air inlet ring, a second air inlet ring, a contraction section, and an excitation coil. One end of the contraction section is connected to one end of the tubular rear electrode, and the other end of the contraction section is connected to a first mixing chamber. The first air inlet ring is located between the tubular rear electrode and the contraction section, and the second air inlet ring is located at the tail end of the tubular rear electrode. Both the first air inlet ring and the second air inlet ring are provided with air inlet holes for inputting gas into the tubular rear electrode. The excitation coil is wound around the outside of the tubular rear electrode.

[0009] a power supply system for supplying power to the tubular rear electrode and the excitation coil;

[0010] The air supply system is used to supply air to the first mixing chamber, the second mixing chamber, the first air intake ring and the second air intake ring.

[0011] Furthermore, the amount of gas introduced into the tubular rear electrode by the gas supply system through the first air inlet ring is 70-90% of the total air intake volume of the arc discharge chamber, and the amount of gas introduced into the tubular rear electrode by the gas supply system through the second air inlet ring is 10-30% of the total air intake volume of the arc discharge chamber.

[0012] Furthermore, the first air intake ring and the second air intake ring are both arranged with a series of tangential air intake holes along their own circumferential directions, and the number and circumferential tangential angle of the air intake holes of the first air intake ring and the second air intake ring are consistent.

[0013] Furthermore, the excitation coil is a spiral coil made of a hollow copper tube, and both ends of the excitation coil are connected to cooling water pipe nozzles, which are used to introduce cooling water. The root of the cooling water pipe nozzle is connected to a cable wiring copper block, which is used to connect to the power supply system through a cable.

[0014] Furthermore, the power supply system includes a power supply, an inductor coil, a transformer, a high-voltage switchgear and a low-voltage switchgear. The three phases of the power supply are connected to the input end of the low-voltage switchgear through cables, and then the output end of the low-voltage switchgear is connected to the primary side of the transformer through cables, and then the secondary side of the transformer is connected to the input end of the high-voltage switchgear through cables, and then the output end of the high-voltage switchgear is connected to the inductor coil, and then the other end of the inductor coil is connected to one end of the excitation coil outside an arc discharge chamber through cables, and the other end of the excitation coil is connected to the connection terminal of the rear electrode of the next arc discharge chamber.

[0015] Furthermore, the plane perpendicular to the inner central axis of the first mixing chamber is a first plane, and the clockwise direction on the first plane, viewed from the side of the first mixing chamber facing away from the second mixing chamber, is the electrical connection direction;

[0016] One output end of the power supply is connected to one end of an excitation coil away from the first mixing chamber, and the other end of the excitation coil is connected to the electrode arm of the next tubular rear electrode in the electrical connection direction through a wire.

[0017] Furthermore, the end of the tubular rear electrode away from the contraction section is connected to a rear end cover, which is used to seal one end of the tubular electrode; an observation window is provided on the rear end cover, through which the movement of the arc root in the tubular rear electrode can be observed.

[0018] Furthermore, it also includes a testing system, which includes a pressure sensor, a temperature sensor, a spectrum, a Hall closed-loop zero-flux current sensor and a zero-flux high-withstand voltage sensor; the Hall closed-loop zero-flux current sensor and the zero-flux high-withstand voltage sensor are used to measure the arc current and arc voltage of the arc discharge chamber, obtain the arc power of each phase arc discharge chamber, and then obtain the total arc power of the AC arc heating assembly; the pressure sensor is used to measure the air conditioning pressure of the arc discharge chamber, the first mixing chamber, the second mixing chamber and the air supply system pipeline and the pressure data on the cooling water inlet and outlet pipes; the temperature sensor is used to measure the inductor coil temperature, the transformer temperature and the arc discharge chamber cooling water return temperature; the spectrum is used to measure the average temperature of the high-temperature airflow of the plasma at the nozzle outlet.

[0019] Furthermore, it also includes a control system, which includes a control computer, a PLC controller and a one-button circuit breaker device. The detection data collected by the test system is transmitted to the control system. When the detection data is abnormal, the control system disconnects the high-voltage switchgear and the low-voltage switchgear; the one-button circuit breaker device is connected to the high and low voltage switchgear.

[0020] Furthermore, the first mixing chamber is provided with an arc discharge chamber installation opening every 120° central angle along the circumferential direction, and the arc discharge chamber installation opening is used for installing the arc discharge chamber.

[0021] In summary, this application has at least the following beneficial technical effects:

[0022] The present invention provides an AC arc discharge gas heating system. This system generates arc discharge energy of varying power by constructing one or more AC arc heating assemblies within a first mixing chamber. Gas is then introduced into a second mixing chamber to achieve mixed heating of the arc and gas, which is then accelerated through a nozzle to produce a high-temperature, high-speed plasma gas jet. By utilizing a specially designed phase shift reduction between excitation and AC arc discharge, as well as the introduction of dual-channel synchronous rotating airflow, the arc's movement on the inner wall of the arc discharge chamber electrode is effectively controlled, reducing contamination of the high-temperature airflow caused by electrode ablation. Furthermore, a systematic, safe, stable, and reliable control system is developed, ensuring the safe and stable operation of the AC arc discharge gas heating system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the AC arc discharge gas heating system of the present invention.

[0024] Figure 2 Schematic diagram of the power supply system of the present invention.

[0025] Figure 3 This is a schematic diagram of the water supply system and gas supply system of the present invention.

[0026] Figure 4 Schematic diagram of the AC discharge assembly of the present invention.

[0027] Description of reference numerals:

[0028] 11. First mixing chamber; 12. Second mixing chamber; 13. Nozzle;

[0029] 21. Inductor coil; 22. Transformer; 23. High-voltage switchgear; 24. Low-voltage switchgear;

[0030] 3. AC arc heating assembly; 31. Tubular rear electrode; 32. First air inlet ring; 33. Second air inlet ring; 34. Contraction section; 35. Excitation coil; 36. Observation window; 37. Rear end cover. DETAILED DESCRIPTION

[0031] To further clarify the objectives, technical solutions, and advantages of this application, the following detailed description of the embodiments disclosed herein is provided in conjunction with the accompanying drawings. By employing the power supply circuit connection method designed in the present invention, the excitation coil generates an alternating magnetic field within the electrode, which periodically magnetically confines the arc root within the electrode, causing it to rotate at high speed and reducing arc erosion of the electrode's inner wall.

[0032] The present application discloses an AC arc discharge gas heating system, such as Figure 1 As shown, it includes: an AC arc heating assembly 3, a first mixing chamber 11, a second mixing chamber 12, a nozzle 13, a power supply system, a test system, a control system, a water cooling system and an air supply system.

[0033] like Figure 3As shown, the second mixing chamber 12 is located downstream of the first mixing chamber 11, and the nozzle 13 is located downstream of the second mixing chamber 12. The first mixing chamber 11 is a hollow cylinder. Three arc discharge chamber mounting openings are arranged at 120° intervals along the circumference of a certain cross-section of the cylinder. The arc discharge chambers are used to mount the arc discharge chambers thereon, with the outlets of the arc discharge chambers located within the first mixing chamber 11. This cross-section forms a set of AC arc heating assemblies. Multiple sets of AC arc heating assemblies can be arranged as needed on different cross-sections of the first mixing chamber 11. Two through holes are provided on each of the two bottom surfaces of the cylinder of the first mixing chamber 11. One of the through holes is connected to the inlet of the downstream second mixing chamber 12, and a transparent quartz glass is installed above the other through hole for observing the arc state inside the first mixing chamber 11.

[0034] like Figure 3 As shown, the second mixing chamber 12 is an internal hollow cylinder, one end of which is connected to the outlet of the first mixing chamber 11, and the other end is connected to the downstream nozzle 13. A plurality of air inlets are evenly distributed along the circumferential direction at the middle position outside the second mixing chamber 12.

[0035] The nozzle 13 is a Laval nozzle 13 , and the inlet end of the nozzle 13 is connected to the outlet end of the second mixing chamber 12 .

[0036] like Figure 1 and Figure 2As shown, the first mixing chamber 11 is provided with several interfaces on the outside to provide mounting support for the AC arc heating assembly. The power supply system consists of a power supply, cables, an inductor 21, a transformer 22, a high-voltage switchgear 23, and a low-voltage switchgear 24. The A, B, and C phases of the power supply are connected to the input end of the low-voltage switchgear 24 via cables. The output end of the low-voltage switchgear 24 is then connected to the primary side of the transformer 22 via cables. The secondary side of the transformer 22 is then connected to the input end of the high-voltage switchgear 23 via cables. The output end of the high-voltage switchgear 23 is then connected to the inductor 21. The other end of the inductor 21 is then connected to one end of the excitation coil 35 outside an arc discharge chamber via cables. The other end of the excitation coil 35 is connected to the terminal of the rear electrode of the next arc discharge chamber. The connection direction is such that, viewed along the gas flow direction along the central axis of the first mixing chamber 11, the output end of the excitation coil 35 outside each phase arc chamber is connected to the electrode arm of the next arc chamber in a clockwise direction from the arc chamber. That is, the plane perpendicular to the central axis of the first mixing chamber 11 is the first plane, and the clockwise direction on the first plane, viewed from the side of the first mixing chamber 11 facing away from the second mixing chamber, is the electrical connection direction; in the power supply system, one output end of the inductor coil is connected to an end of an excitation coil 35 away from the first mixing chamber 11, and the other end of the excitation coil 35 is connected to the electrode arm of the next tubular rear electrode 31 in the electrical connection direction through a wire.

[0037] The test system includes current, voltage, temperature and pressure measurements, and the control system includes a control computer, a PLC controller and a one-button circuit breaker device.

[0038] like Figure 4As shown, the AC arc heating assembly is composed of three identical arc discharge chambers, each of which is connected to a tubular rear electrode 31, a first air inlet ring 32, a second air inlet ring 33, a contraction section 34, and a housing. The contraction section 34 is connected to one end of the tubular rear electrode 31. The diameter of the contraction section 34 along the end away from the tubular rear electrode 31 is smaller than the diameter of the connection end of the contraction section 34 and the tubular rear electrode 31. The small diameter section of the contraction section 34 is connected to the first mixing chamber 11. The first air inlet ring 32, located between the tubular rear electrode 31 and the constricted section 34, forms the primary air inlet channel for the arc discharge chamber, receiving 90% of the total air intake from the air supply system. The second air inlet ring 33, located at the rear end of the tubular rear electrode 31, forms the secondary air inlet channel for the arc discharge chamber, receiving 10% of the total air intake from the air supply system. The air intake of the first and second air inlet rings 32, 33 is achieved by arranging a series of tangential air inlet holes along the circumference of the ring. The number of holes and the tangential angles of the holes are consistent in both rings. The air intake settings of the first and second air inlet rings 32, 33 protect the rear end cover 37 and the observation window 36, preventing the arc root from approaching the rear end cover and burning it.

[0039] The excitation coil 35 is a hollow copper tube wound into a spiral coil with a specific radius (larger than the outer diameter of the arc discharge chamber). A cooling water nozzle is welded to each end of the spiral coil. A copper block with a hollow circular hole for cable connection is welded to the base of the nozzle, forming a solenoid water-electricity connection device at each end of the excitation coil 35. The excitation coil 35 is located outside the arc discharge chamber, coaxially and in the same section as the tubular rear electrode 31.

[0040] Water cooling is achieved through the excitation coil 35 , which can accelerate the rotation of the arc root inside the tubular rear electrode 31 and reduce the burning of the arc root on the inner surface of the electrode.

[0041] The test system uses a Hall closed-loop zero-flux current sensor and a zero-flux high-withstand voltage sensor to measure the arc current and arc voltage of the arc discharge chamber, obtains the arc power of each phase of the arc discharge chamber, and then obtains the total arc power of the heater; uses a pressure sensor to obtain the air conditioning pressure of the arc discharge chamber, the first mixing chamber 11, the second mixing chamber 12, and the air supply system pipeline and the pressure data on the cooling water inlet and outlet pipes; uses a temperature sensor to obtain the temperature data of the inductor coil 21, the transformer 22, and the cooling water return temperature data of the arc discharge chamber, and uses spectroscopy to obtain the average temperature of the plasma high-temperature airflow at the nozzle 13 outlet.

[0042] The gas supply system is respectively connected to the first air inlet ring 32, the second air inlet ring 33, the first mixing chamber 11 and the second mixing chamber 12 inside the arc discharge chamber of the AC arc heating assembly, and the air intake flow of each path is controlled by arranging a sonic nozzle on the air inlet pipe.

[0043] The control system consists of a control computer, a PLC controller and a one-button circuit breaker device, which transmits the current, voltage, temperature and pressure parameters collected by the test system to the control system. When one of the arc chamber pressure, the first mixing chamber 11 pressure, the second mixing chamber 12 pressure, and the pressure on the cooling water inlet and outlet pipes is abnormal, or when the inductor coil 21, the transformer 22 and the arc chamber return water temperature are abnormal, the high and low voltage switch cabinets 24 are automatically disconnected through the control system to stop the heater operation.

[0044] The one-button circuit breaker device is directly connected to the high and low voltage switch cabinet 24. Through a one-button button, the high and low voltage switch cabinet 24 can be directly disconnected in an emergency such as a power outage or a system crash of the control system, thereby stopping the heater operation in an emergency.

[0045] The temperature and pressure fluctuations refer to the temperature or pressure changes being greater than a preset relative change rate within 200ms when the working gas, current and voltage remain unchanged during the operation of the AC arc discharge gas heating system.

[0046] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

[0047] The present application has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art will appreciate that, without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present application, all of which fall within the scope of the present application. The scope of protection of the present application shall be determined by the appended claims.

Claims

1. An AC arc discharge gas heating system, characterized in that: include: a first mixing chamber (11); An AC arc heating assembly (3) includes a plurality of arc discharge chambers, each arc discharge chamber including a tubular rear electrode (31), a first air inlet ring (32), a second air inlet ring (33), a contraction section (34) and an excitation coil (35), one end of the contraction section (34) being connected to one end of the tubular rear electrode (31), the other end of the contraction section (34) being connected to a first mixing chamber (11), the first air inlet ring (32) being located between the tubular rear electrode (31) and the contraction section (34), the second air inlet ring (33) being located at the tail end of the tubular rear electrode (31), the first air inlet ring (32) and the second air inlet ring (33) both being provided with air inlet holes for inputting gas into the tubular rear electrode (31); and the excitation coil (35) being wound around the outside of the tubular rear electrode (31); A power supply system for supplying power to the tubular rear electrode (31) and the excitation coil (35); An air supply system is used for supplying air to the first mixing chamber (11), the second mixing chamber (12), the first air intake ring (32) and the second air intake ring (33).

2. The AC arc discharge gas heating system according to claim 1, characterized in that: The amount of gas introduced into the tubular rear electrode (31) by the first air inlet ring (32) from the air supply system is 70-90% of the total air intake volume of the arc discharge chamber, and the amount of gas introduced into the tubular rear electrode (31) by the second air inlet ring (33) from the air supply system is 10-30% of the total air intake volume of the arc discharge chamber.

3. The AC arc discharge gas heating system according to claim 1, characterized in that: The first air intake ring (32) and the second air intake ring (33) are both provided with a series of tangential air intake holes along their own circumferential directions, and the number of air intake holes and the circumferential tangential angles of the air intake holes of the first air intake ring (32) and the second air intake ring (33) are consistent.

4. The AC arc discharge gas heating system according to claim 1, characterized in that: The excitation coil (35) is a spiral coil wound around a hollow copper tube. Both ends of the excitation coil (35) are connected to cooling water nozzles for introducing cooling water. The root of the cooling water nozzle is connected to a cable connection copper block for connecting to a power supply system via a cable.

5. The AC arc discharge gas heating system according to claim 1, characterized in that: The power supply system comprises a power supply, an inductor (21), a transformer (22), a high-voltage switch cabinet (23) and a low-voltage switch cabinet (24), wherein the three phases of the power supply are connected to the input end of the low-voltage switch cabinet (24) through cables, and then the output end of the low-voltage switch cabinet (24) is connected to the primary side of the transformer (22) through cables, and then the secondary side of the transformer (22) is connected to the input end of the high-voltage switch cabinet (23) through cables, and then the output end of the high-voltage switch cabinet (23) is connected to the inductor (21), and then the other end of the inductor (21) is connected to one end of an excitation coil (35) outside an arc discharge chamber through cables, and the other end of the excitation coil (35) is connected to the connection terminal of the rear electrode of the next arc discharge chamber.

6. The AC arc discharge gas heating system according to claim 5, characterized in that: The plane perpendicular to the central axis of the first mixing chamber (11) is a first plane, and the clockwise direction on the first plane, viewed from the side of the first mixing chamber (11) facing away from the second mixing chamber, is the electrical connection direction; One output end of the inductor coil (21) is connected to one end of an excitation coil (35) away from the first mixing chamber (11), and the other end of the excitation coil (35) is connected to the electrode arm of the next tubular rear electrode (31) in the electrical connection direction through a wire.

7. The AC arc discharge gas heating system according to claim 1, characterized in that: The end of the tubular rear electrode (31) away from the contraction section (34) is connected to a rear end cover (37), and the rear end cover (37) is used to seal one end of the tubular electrode (31); the rear end cover (37) is provided with an observation window (36), through which the movement of the arc root in the tubular rear electrode (31) can be observed.

8. The AC arc discharge gas heating system according to claim 1, characterized in that: It also includes a test system, which includes a pressure sensor, a temperature sensor, a spectrum, a Hall closed-loop zero-flux current sensor, and a zero-flux high-withstand voltage sensor; The Hall closed-loop zero-flux current sensor and the zero-flux high-voltage withstand voltage sensor are used to measure the arc current and arc voltage of the arc discharge chamber, and then obtain the arc power of each phase arc discharge chamber and then obtain the total arc power of the AC arc heating assembly (3); the pressure sensor is used to measure the gas pressure of the arc discharge chamber, the first mixing chamber (11), the second mixing chamber (12) and the gas supply system pipeline and the pressure data on the cooling water inlet and outlet pipes; the temperature sensor is used to measure the temperature of the inductor coil (21), the temperature of the transformer (22) and the return water temperature of the arc discharge chamber cooling water; the spectrum is used to measure the average temperature of the plasma high-temperature airflow at the nozzle (13) outlet.

9. The AC arc discharge gas heating system according to claim 1, characterized in that: The invention also includes a control system, which includes a control computer, a PLC controller and a one-button circuit breaking device. The detection data collected by the test system is transmitted to the control system. When the detection data is abnormal, the control system disconnects the high-voltage switch cabinet (23) and the low-voltage switch cabinet (23); the one-button circuit breaking device is connected to the high-voltage and low-voltage switch cabinets (24).

10. The AC arc discharge gas heating system according to claim 1, characterized in that: The first mixing chamber (11) has a plurality of arc discharge chamber installation openings uniformly arranged along the circumference, and the arc discharge chamber installation openings are used for installing the arc discharge chamber.

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