An experimental platform for plasma-assisted oxidation, pyrolysis and reforming of gas-liquid fuels

Abstract

The present invention discloses an experimental platform for plasma-assisted oxidation, pyrolysis and reforming of gas-liquid fuels, which includes an air intake system, a reaction system, a power supply system, an exhaust system and a product detection system. The air intake system provides a liquid fuel pump and an evaporation tank for liquid fuel sampling and evaporation; the reaction system includes a quartz flow tube with a double-layer dielectric barrier discharge structure and an electric heating furnace, which can obtain uniform, high-energy, high-density non-equilibrium plasma at different temperatures; the power supply system can meet the requirements of various discharge forms; the piston-type negative pressure gas collection device included in the product detection system can meet the needs of conducting experiments in a negative pressure environment. The present invention provides an experimental platform and method for plasma-assisted oxidation, pyrolysis and reforming in a wide pressure and temperature range and in a variety of power supply forms, which is helpful for the study of plasma-combustion chemical reaction kinetics of gas-liquid fuels and the development of related mechanisms.

Description

Technical Field

[0001] The invention belongs to the field of novel combustion technology, and in particular relates to an experimental platform for plasma-assisted oxidation, pyrolysis and reforming of gas-liquid fuels. Background Art

[0002] As the main power source for vehicles, ships, airplanes and other transportation vehicles, engines play an important role in modern transportation systems. The ignition and combustion of fuels have a great impact on the power, economy and emissions of engines. The energy trend of energy conservation and emission reduction and the development of clean alternative fuels has put forward new development directions for engine combustion technology. Plasma is the fourth state of matter different from gas, liquid and solid. The particles such as electrons, ions, active free radicals, excited state components contained in plasma can promote combustion through thermal effects, kinetic effects and transport effects. Plasma-assisted combustion, as a new technical means to regulate the ignition and combustion characteristics of engines, has great application value in broadening the ignition limit, shortening the ignition delay time, and improving flame stability. The most commonly used plasma in plasma combustion-assisted technology is non-equilibrium plasma, that is, the electron temperature is high, while the temperature of ions and neutral particles is low. This plasma can be generated by dielectric barrier discharge, sliding arc discharge, corona discharge and microwave discharge.

[0003] At present, more attention has been paid to experimental and simulation studies on plasma-assisted oxidation, pyrolysis and reforming of gaseous fuels, while relevant studies on liquid fuels are relatively lacking. In addition, the kinetic enhancement of nonequilibrium plasma on combustion is more significant under low temperature conditions, but due to the complex interaction between plasma reaction and combustion reaction, the current reaction kinetic model still has great uncertainty and requires the support of a large amount of experimental data. Summary of the invention

[0004] The purpose of the present invention is to provide an experimental platform for plasma-assisted oxidation, pyrolysis and reforming of gas and liquid fuels, specifically an experimental device that can detect and analyze the intermediate reaction products of gas or liquid fuels during plasma-assisted oxidation, pyrolysis or reforming reactions under different discharge forms and different reaction temperatures, which is beneficial to the study of plasma-combustion chemical reaction kinetics of gas and liquid fuels and the development of related mechanisms.

[0005] The present invention is implemented by the following technical solutions:

[0006] An experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming, which is used for the study of oxidation, pyrolysis and reforming of gaseous fuel and liquid fuel in plasma, and includes an air intake system, a reaction system, a power supply system, a product detection system and an exhaust system;

[0007] The air intake system is used to provide mixing and heating of the dilution gas and the fuel gas. When the fuel is liquid, the liquid fuel is first vaporized and then mixed with the dilution gas;

[0008] The reaction system is used to provide a reaction area with controllable temperature and pressure for the experimental process, and at the same time provide a double dielectric barrier discharge structure to generate uniform non-equilibrium plasma;

[0009] The power supply system is used to provide a continuous electric field, detect the voltage and current during the discharge process, and ensure the participation of non-equilibrium plasma in the reaction process;

[0010] Product detection system, used to collect constant volume of reaction products and detect them offline, to achieve diagnosis and analysis of microscopic components in the energy conversion process;

[0011] The exhaust system is used to control the pressure changes in the reactor and discharge the gas produced by the reaction out of the system.

[0012] A further improvement of the present invention is that the air intake system includes a gas fuel, a mass flow meter, a flow meter controller, a liquid fuel, a liquid injection pump, a heating belt and an evaporation tank;

[0013] The gas fuel and dilution gas are connected to the stainless steel pipe through the mass flow meter for heating and mixing. The mass flow meter is powered by the flow meter controller and controls the flow rate.

[0014] If the fuel is liquid, the liquid is connected to the evaporator through a liquid injection pump for vaporization. The heating belt outside the evaporator is set to a temperature above the boiling point of the target fuel. The evaporated gas and the dilution gas are also heated and mixed in the stainless steel pipe.

[0015] A further improvement of the present invention is that the reaction system comprises an electric heating furnace, a quartz flow tube, a K-type thermocouple, a digital thermometer, a sealing flange, an external copper ring electrode, an internal copper rod electrode and a quartz tube coated on the copper rod electrode;

[0016] Both ends of the entire reaction structure are sealed by sealing flanges combined with rubber rings, and the reactor temperature is controlled by an electric heating furnace; the preset coaxiality is ensured between the four components of the external copper ring electrode, the quartz flow tube, the internal copper rod electrode and the quartz tube coated on the copper rod electrode, thereby forming a uniform discharge area; the reaction gas can enter the quartz flow tube from the air inlet end, flow through the discharge area, and flow out from the exhaust end; the K-type thermocouple is placed into the quartz flow tube through the opening on the sealing flange to monitor the reaction temperature in real time, and the probe is located at the end of the discharge area to avoid interference with the discharge.

[0017] A further improvement of the present invention is that the power supply system includes a voltage probe, a current probe, an oscilloscope and a discharge power supply;

[0018] The positive and negative poles of the discharge power supply are respectively connected to the external copper ring electrode and the internal copper rod electrode to provide voltage therefor. The discharge voltage and current are detected by the voltage probe and the current probe and displayed and recorded on the oscilloscope.

[0019] A further improvement of the present invention is that the experimental platform supports plasma discharges generated by a variety of discharge power sources.

[0020] A further improvement of the present invention is that the quartz flow tube has a double-layer dielectric barrier discharge structure, which can generate a more uniform discharge electric field.

[0021] A further improvement of the present invention is that the electric heating furnace provides a wide range of initial temperature conditions of 298K-1200K for the fuel reaction;

[0022] The placement of the K-type thermocouple enables it to monitor the actual reaction temperature of the fuel and plasma, and effectively avoids the influence of the thermocouple on the discharge electric field.

[0023] A further improvement of the present invention is that the product detection system includes a negative pressure gas collection device, a vacuum gauge, a gas chromatograph and a gas chromatograph / mass spectrometer and a computer;

[0024] The gas after the reaction is collected and compressed by a negative pressure gas collection device, and the pressure in the collection device is detected by a vacuum gauge. The compressed reaction gas enters the gas chromatograph and gas chromatography / mass spectrometer for component detection, and the results are fed back to the computer.

[0025] A further improvement of the present invention is that the use of a negative pressure gas collection device allows the reaction to be carried out under negative pressure conditions of 0-100 kPa absolute pressure.

[0026] A further improvement of the present invention is that the product exhaust system includes a micro-regulating valve and a vacuum pump;

[0027] By rotating and adjusting the micro valve, the amount of gas discharged from the vacuum pump into the atmosphere is controlled, and the pressure in the reaction structure is further controlled to keep it constant at a negative pressure state, and the excess product gas is discharged in time.

[0028] The present invention has at least the following beneficial technical effects:

[0029] The present invention provides an experimental platform for plasma-assisted oxidation, pyrolysis and reforming of gas and liquid fuels. The experimental platform first achieves mixing and intake of gas or liquid fuel and dilution gas through an intake system, and then applies an external voltage to generate plasma by discharging between the inner and outer electrodes of a quartz flow tube, which reacts with the gas flowing into the quartz tube. The product gas is collected by a negative pressure gas collection device and pressurized to above an atmospheric pressure, so that the product gas can smoothly enter the detection system for detection and analysis. In summary, the present invention has the following advantages:

[0030] 1. The present invention can be used for the study of oxidation, pyrolysis and reforming of gaseous fuels and liquid fuels in plasma.

[0031] 2. The present invention generates a more uniform discharge electric field through a double-layer dielectric barrier discharge structure.

[0032] 3. The present invention supports plasma discharge generated by various power supply forms.

[0033] 4. The present invention provides a wide range of initial temperature conditions for fuel reaction through electric furnace heating.

[0034] 5. The placement of the thermocouple in the present invention enables it to monitor the actual reaction temperature of the fuel and plasma, and effectively avoids the influence of the thermocouple on the discharge electric field.

[0035] 6. The negative pressure gas collection device used in the present invention allows the fuel reaction to be carried out under negative pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a structural diagram of the experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming of the present invention.

[0037] Figure 2 It is a partial cross-sectional view of the discharge area of ​​the double-layer dielectric barrier discharge structure.

[0038] Figure 3 It is a left side cross-sectional view of the double-layer dielectric barrier discharge structure.

[0039] Description of reference numerals:

[0040] 1- gas fuel, 2- liquid fuel, 3- mass flow meter, 4- flow meter controller, 5- liquid injection pump, 6- evaporation tank, 7- heating belt, 8- electric heating furnace, 9- quartz flow tube, 10- thermocouple, 11- digital thermometer, 12- sealing flange, 13- voltage probe, 14- current probe, 15- oscilloscope, 16- discharge power supply, 17- micro regulating valve, 18- vacuum pump, 19- negative pressure gas collection device, 20- vacuum gauge, 21- gas chromatograph, 22- gas chromatograph / mass spectrometer, 23- computer, 24- external copper ring electrode, 25- internal copper rod electrode, 26- quartz tube. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings.

[0042] See also Figures 1 to 3 The present invention provides an experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming, wherein the air intake system is mainly composed of gas fuel 1, liquid fuel 2, mass flow meter 3, flow meter controller 4, liquid injection pump 5, evaporation tank 6 and heating belt 7; the reaction system is mainly composed of electric heating furnace 8, quartz flow tube 9, sealing flange 12, thermocouple 10 and digital thermometer 11, wherein the quartz flow tube 9 includes an external copper ring electrode 24, a built-in copper rod electrode 25 and a quartz tube 26 coated on the inner electrode; the power supply system is composed of a voltage probe 13, a current probe 14, an oscilloscope 15 and a discharge power supply 16; the exhaust system is composed of a micro-regulating valve 17 and a vacuum pump 18; the product detection system is composed of a negative pressure gas collection device 19, a gas chromatograph 21, a gas chromatograph / mass spectrometer 22 and a computer 23.

[0043] Under the action of an external electric field, the reaction system generates uniform plasma discharge in the discharge region of the flow tube through the copper rod electrode and the copper ring electrode placed inside and outside the quartz flow tube 9 and kept coaxial.

[0044] The air intake system includes an evaporator 6 for evaporating the liquid fuel 2. The outside of the evaporator 6 is heated by a heating belt 7 to keep the temperature inside the tank above the boiling point of the liquid fuel 2. Steel balls are added to the evaporator 6 to increase the heat exchange area, which promotes the evaporation of the liquid fuel 2 on the one hand and facilitates the mixing of the carrier gas and the gasified fuel on the other hand. The design of the evaporator 6 enables the present invention to be used not only for the research of gas fuel 1, but also for the research of liquid fuel 2. The heating process is to keep the liquid fuel in a gasified state at all times, while reducing the temperature gradient between the reaction system and the mixed reaction gas.

[0045] The reaction system adopts a double-layer dielectric barrier discharge structure, including a quartz flow tube body, an external copper ring electrode 24, an internal copper rod electrode 25, and a quartz tube 26 wrapped around the internal copper rod electrode 25, wherein the external copper ring electrode 24 and the internal copper rod electrode 25 ensure a certain coaxiality. A double-layer dielectric barrier discharge system is formed by inserting a double-layer insulating medium between the two discharge electrodes, which can obtain a non-equilibrium plasma with large flow, high energy and high density in a certain space, and is more conducive to the uniformity of discharge.

[0046] The reaction system comprises an electric heating furnace 8 for heating the discharge structure, thereby providing a wide range of initial temperature conditions for the gas-liquid fuel reaction.

[0047] The thermocouple 10 used to monitor the reaction temperature is directly located inside the flow field of the gas flow, rather than being separated from the gas flow field by a layer of insulating medium. This placement allows the temperature monitored by the thermocouple 10 to truly reflect the actual temperature when the fuel molecules react with the plasma; and the probe of the thermocouple 10 is located at the end of the plasma discharge area, which effectively avoids the interference of the thermocouple 10 on the discharge field strength.

[0048] A negative pressure gas collection device 19 is used to collect negative pressure gas by evacuating the device, and the collected gas is smoothly introduced into the detection system by manual pressure increase. This negative pressure gas collection device 16 provides a wide range of initial pressure conditions for the gas-liquid fuel reaction, allowing the reaction to proceed in a negative pressure environment.

[0049] In the power supply system, the discharge power supply 16 can be easily replaced, and various forms of plasma discharge such as nanosecond pulse discharge, radio frequency discharge, direct current discharge, and alternating current discharge can be performed according to different research requirements.

[0050] Working process: First, turn on the electric heating furnace 8 to raise the temperature to the set value. When it is necessary to conduct research under a negative pressure environment, first evacuate the negative pressure gas collection device 19 and the quartz flow tube 9 through the vacuum pump 18. The gas fuel 1 is inhaled and mixed through the mass flow meter 3 controlled by the flow meter controller 4, and the liquid fuel 2 enters the evaporation tank 6 through the liquid injection pump 5. The heating belt 7 heats the temperature of the evaporation tank 6 to above the boiling point of the liquid fuel, so that the fuel evaporates and merges into the main gas path and enters the quartz flow tube 9. Turn on the vacuum pump 18, and adjust the micro-adjusting valve 17 to keep the inside of the quartz flow tube 9 in a constant negative pressure state. At this time, the negative pressure gas collection device 19 in a vacuum state has not started to collect gas. Then, by setting the parameters of the discharge power supply 16 such as voltage, frequency, pulse width, etc., a voltage is applied between the external copper ring electrode 24 and the internal copper rod electrode 26 to start discharge. The discharge voltage and discharge current are detected by the voltage probe 13 and the current probe 14 respectively and displayed and recorded on the oscilloscope 15. After the discharge process is stable, the negative pressure collection device 19 starts to collect the reaction gas, and the pressure in the device is detected and displayed by the vacuum gauge 20. After the gas collection is completed, the collected reaction gas is manually pressurized to enter the gas chromatograph 21 and the gas chromatograph / mass spectrometer 22 for product component detection, and the detection results are fed back to the computer 23. Through data analysis, the chemical reaction kinetic characteristics of gas fuel or liquid fuel in the plasma-assisted oxidation, pyrolysis and reforming process under certain temperature and pressure conditions can be obtained, which is helpful for the study of the plasma-combustion chemical reaction mechanism.

Claims

1. An experimental platform for plasma-assisted oxidation, pyrolysis and reforming of gas and liquid fuels, characterized in that: This experimental platform is used to study the oxidation, pyrolysis and reforming of gaseous fuels and liquid fuels in plasma, including the intake system, reaction system, power supply system, product detection system and exhaust system; An air intake system is used to provide mixing and heating of dilution gas and fuel gas. When the fuel is liquid, the liquid fuel is first vaporized and then mixed with the dilution gas. The air intake system comprises a gas fuel (1), a mass flow meter (3), a flow meter controller (4), a liquid fuel (2), a liquid injection pump (5), a heating belt (7) and an evaporation tank (6). The gas fuel (1) and the dilution gas are connected to a stainless steel pipe through a mass flow meter (3) for heating and mixing. The mass flow meter (3) is powered by the flow meter controller (4) and controls the flow rate. If the fuel is liquid, the liquid is connected to the evaporation tank (6) through a liquid injection pump (5) for vaporization. The heating belt (7) provided outside the evaporation tank (6) is set to a temperature above the boiling point of the target fuel. The evaporated gas and the dilution gas are also heated and mixed in the stainless steel pipe. The reaction system is used to provide a reaction area with controllable temperature and pressure for the experimental process, and at the same time provide a double dielectric barrier discharge structure to generate uniform non-equilibrium plasma; The power supply system is used to provide a continuous electric field, detect the voltage and current during the discharge process, and ensure the participation of non-equilibrium plasma in the reaction process; Product detection system, used to collect constant volume of reaction products and detect them offline, to achieve diagnosis and analysis of microscopic components in the energy conversion process; An exhaust system, used to control the pressure change in the reactor and discharge the gas generated by the reaction out of the system; The product exhaust system includes a micro-regulating valve (17) and a vacuum pump (18); by rotating and regulating the micro-valve (17), the amount of gas discharged from the vacuum pump (18) into the atmosphere is controlled, and the pressure in the reaction structure is further controlled to be constant in a negative pressure state, and the excess product gas is discharged in time.

2. The experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming according to claim 1, characterized in that: The reaction system comprises an electric heating furnace (8), a quartz flow tube (9), a K-type thermocouple (10), a digital thermometer (11), a sealing flange (12), an external copper ring electrode (24), an internal copper rod electrode (25), and a quartz tube (26) coated on the copper rod electrode; The two ends of the entire reaction structure are sealed by sealing flanges (12) combined with rubber rings, and the temperature of the reactor is controlled by an electric heating furnace (8); the four components of the external copper ring electrode (24), the quartz flow tube (9), the internal copper rod electrode (25) and the quartz tube (26) coated on the copper rod electrode are ensured to have a preset coaxiality, thereby forming a uniform discharge area; the reaction gas can enter the quartz flow tube (9) from the air inlet end, flow through the discharge area, and flow out from the exhaust end; the K-type thermocouple (10) is placed in the quartz flow tube (9) through the opening on the sealing flange (12) to monitor the reaction temperature in real time, and the probe is located at the end of the discharge area to avoid interference with the discharge.

3. The experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming according to claim 2, characterized in that: The power supply system comprises a voltage probe (13), a current probe (14), an oscilloscope (15) and a discharge power supply (16); The positive and negative poles of the discharge power supply (16) are respectively connected to the external copper ring electrode (24) and the internal copper rod electrode (25) to provide voltage thereto. The discharge voltage and current are detected by the voltage probe (13) and the current probe (14) and displayed and recorded on the oscilloscope (15).

4. The experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming according to claim 3, characterized in that: The experimental platform supports plasma discharge generated by a variety of discharge power sources (16).

5. The experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming according to claim 2, characterized in that: The quartz flow tube (9) has a double-layer dielectric barrier discharge structure, which can generate a more uniform discharge electric field.

6. The experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming according to claim 2, characterized in that: The electric heating furnace (8) provides a wide range of initial temperature conditions of 298K-1200K for the fuel reaction; The placement position of the K-type thermocouple (10) enables it to monitor the actual reaction temperature of the fuel and plasma, and effectively avoids the influence of the thermocouple on the discharge electric field.

7. The experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming according to claim 1, characterized in that: The product detection system comprises a negative pressure gas collecting device (19), a vacuum gauge (20), a gas chromatograph (21), a gas chromatograph / mass spectrometer (22) and a computer (23); The gas after the reaction is collected and compressed by a negative pressure gas collecting device (19), and the pressure in the collecting device is detected by a vacuum gauge (20). The compressed reaction gas enters a gas chromatograph (21) and a gas chromatograph / mass spectrometer (22) for component detection, and the results are fed back to a computer (23).

8. The experimental platform for plasma-assisted gas-liquid fuel oxidation, pyrolysis and reforming according to claim 7, characterized in that: The use of the negative pressure gas collection device (19) allows the reaction to be carried out under negative pressure conditions of 0-100 kPa absolute pressure.

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