CN104062154A - Sampling device of collaborative particulates of low-temperature plasma generator and sampling method - Google Patents

Abstract

The invention discloses a low-temperature plasma generator cooperative particulate matter sampling device and a sampling method, and relates to the technical field of purification treatment of harmful exhaust gases from automobiles. The device of the present invention includes a total air intake pipe (1), a bracket A (5), a plasma generator (6), an air intake pipe (7), a particle sampling device A (10), a particle sampling device B (14), and an exhaust pipe (17), bracket B (18), main exhaust pipe (20), base (21). In combination with the particle sampling device, the present invention can obtain a particle sample before low-temperature plasma treatment by opening valve A (8), and obtain a particle sample after low-temperature plasma treatment by opening valve B (16). It can be used to test and analyze the particle samples before and after the action of low-temperature plasma, so as to obtain the law of the action of low-temperature plasma on particles. The device of the invention provides convenient conditions for revealing the research on the action mechanism of the low-temperature plasma treatment of the particles.

Description

A low-temperature plasma generator cooperative particle sampling device and sampling method

technical field

The invention relates to the technical field of purification treatment of harmful exhaust gas from diesel engines.

Background technique

A few days ago, serious "smog" phenomenon appeared in many areas of China, causing significant negative impact on the environment, human health and economy. Studies have found that inhalable particulate matter is the main cause of "smog". Therefore, the primary task of solving "smog" pollution is to effectively control inhalable particulate matter. Studies have shown that low-temperature plasma can effectively reduce particulate matter emissions without causing secondary pollution. The low-temperature plasma generator is mainly composed of a plasma power supply, a high-voltage electrode, a dielectric layer and a low-voltage electrode. Among them, the high-voltage electrode is connected to the plasma power supply, the low-voltage electrode is grounded, and the dielectric layer is placed between the two electrodes, and a uniform and stable discharge phenomenon will be formed between the two electrodes.

Low-temperature plasma technology has been widely studied in the field of exhaust gas treatment. Chinese patent CN201110057179.0 provides a low-temperature plasma cooperative two-phase catalytic device and a method for treating harmful exhaust gases, which is suitable for the purification of harmful exhaust gases from diesel engines. Its technology consists of intake and exhaust ports, plasma generators, oxidation-phase catalytic devices, and reduction-phase catalytic devices. Its technology first passes the harmful exhaust gas through the oxidation phase catalytic device for oxidation phase catalysis, then divides the gas into three or more streams and enters the double dielectric barrier discharge low-temperature plasma generator respectively, performs low-temperature plasma dielectric barrier discharge on the gas, and finally passes the reduction The phase catalysis device performs reduction phase catalysis on the gas. Chinese patent CN200410039002.8 provides a low-temperature plasma fuel-saving tail gas purification device for various internal combustion engines. The device is composed of a high-frequency high-voltage pulse power supply, a plasma generator, a connection plate, an air pipe and a nozzle. The internal combustion engine is equipped with this device, which can promote rapid and complete combustion, eliminate black smoke, save fuel by 8%-20%, and reduce the total emission of carbon monoxide, hydrocarbons and nitrogen oxides by more than 50%. Chinese patent CN 200810235539 provides a honeycomb dielectric barrier discharge low-temperature plasma generator device. The device structure includes a shell, a composite high-voltage electrode, a quartz medium, a honeycomb-arranged low-voltage electrode and a catalytic chamber, and an air intake outside the shell. The outlet is the exhaust port at the bottom of the catalytic chamber. This technology can ensure the safe and reliable operation of the low-temperature plasma generator in the diesel engine exhaust bench test and research work, and has good shock resistance, but the residence time of the gas components in the plasma gas phase reaction zone is relatively short, and the chemical reaction is not very sufficient. . Chinese patent CN200410065415.3 provides an integrated low-temperature plasma catalytic reactor for tail gas purification, the device includes a shell, a honeycomb carrier catalyst, and a low-temperature plasma generator, and is characterized in that the honeycomb carrier catalyst is installed on the shell In the air outlet. The device uses the synergistic purification function between low-temperature plasma purification and catalyst purification, uses high-energy active substances generated by low-temperature plasma to improve the reactivity of the catalyst, reduces the light-off temperature of the catalyst, and improves the exhaust gas purification rate.

The application of low-temperature plasma generators to reduce particulate matter emissions has become a research hotspot in the field of diesel engine aftertreatment, and some results have been achieved. However, the research on the mechanism of the reduction of particulate matter by low-temperature plasma technology is not deep enough, and the reduction mechanism is not clear enough. Diesel engine particulate matter has many and complex components. Studying the mechanism of action of low-temperature plasma on different components of particulate matter will help reveal the mechanism of action of low-temperature plasma technology to reduce particulate matter emissions.

Contents of the invention

The invention provides a low-temperature plasma generator cooperative particle sampling device and a sampling method, which is suitable for a full-flow diesel engine bench test, and can obtain particle samples before and after low-temperature plasma action. The particle sampling device is simple and easy to operate. The action mechanism of low-temperature plasma treatment of particulate matter provides favorable conditions.

The technical scheme adopted in the present invention is: before the plasma generator, a control valve A and a detachable particle sampling device A are installed behind the main air intake pipe; a control valve B and a detachable particle sampling device are installed before the main exhaust pipe. Sampling device B. In the discharge area, a structure in which three or more plasma generators work in parallel is adopted, and the brackets are separated from each other by a certain distance to prevent mutual influence between the electrodes of the generators. The material of the brackets is insulating and high-temperature-resistant polytetrafluoroethylene . This structure will generate a large number of active free radicals to chemically react with the harmful exhaust of the diesel engine during the discharge process, which can not only promote the chemical reaction, but also enable the rapid occurrence of chemical reactions that are difficult to produce under normal conditions, and enhance the reduction of harmful emissions from the diesel engine. effectiveness. The structure of three or more plasma generators working in parallel is suitable for full-flow bench tests, and can be adjusted according to different types of engines, which is more practical. In addition, this structure increases the residence time of exhaust gas components in the plasma gas phase reaction zone, has high energy utilization rate, and enhances the conversion efficiency of harmful gas components. Tests show that the device can effectively improve the conversion efficiency of the particulate emission of the diesel engine to more than 60%, and the fuel consumption corresponding to the increase of the diesel engine is within 5%.

The low-temperature plasma generator cooperative particle sampling device of the present invention includes a main air intake pipe, a support A, a particle sampling device A, a plasma generator, a particle sampling device B, an exhaust pipe, a support B, and a total exhaust pipe. The plasma generator consists of an intake pipe, a high-voltage electrode, a plug A, a dielectric layer, a low-voltage electrode, an exhaust pipe, and a plug B. The medium layer is a circular tube-shaped quartz glass tube; the circular tube-shaped quartz glass tube is arranged on the support A and the support B, and the tube walls at both ends of the quartz glass tube are respectively provided with an air inlet pipe and an exhaust pipe. The bracket A, the plug A and the base are made of polytetrafluoroethylene; the high-voltage electrode is a thin copper rod placed in a quartz glass tube, and the two ends of the high-voltage electrode pass through the two plugs respectively. The low-voltage electrode is a constantan electrode, and the low-voltage electrode is in the shape of a round tube, wrapped on the outside of the tube wall of the quartz glass tube, and grounded through a lead wire.

There are three or more plasma generators, which can be adjusted according to different types of engines. The total intake pipes and total exhaust pipes of three or more plasma generators are evenly arranged on the circumference.

The method for treating the harmful exhaust gas of the diesel engine in the present invention first passes the harmful exhaust gas through the main exhaust pipe, then divides the gas into three or more streams and enters the double dielectric barrier discharge low-temperature plasma generator respectively, and performs low-temperature plasma dielectric barrier discharge on the gas , and finally through the main exhaust pipe. After the gas enters the double dielectric barrier discharge low-temperature plasma generator, the gas flow direction is forcibly changed to prolong the residence time of the gas in the double dielectric barrier discharge low-temperature plasma generator. In addition, through the particle sampling device A and the particle sampling device B, the particle samples before and after the low-temperature plasma action can be obtained at any time, which is convenient for the later analysis and processing of the particles.

The novel low-temperature plasma generator cooperates with the particle sampling device, wherein the particle sampling device is equipped with a valve control, which is easy to operate, sealed by frosting, and the device is easy to disassemble, convenient and reliable. The device adopts an integral structure, which ensures the uniformity of the gas entering each plasma generator and has good working reliability. The total intake pipe, the total exhaust pipe and the exhaust device are connected with silicone tubes, so that in the actual application process, it can resist the impact of the violent vibration of the exhaust of the diesel engine, achieve the effect of anti-vibration and stable work, and ensure the reliability and accuracy of the work. .

The beneficial effect of the present invention is that the device is an integrated molding structure composed of three or more plasma generators, which can be controlled according to different engine displacements, and is suitable for full-flow treatment of various types of engine harmful gases emission. The particle sampling device can obtain the particle samples before and after the low-temperature plasma action at any time, which is convenient for the later analysis and processing of the particles. The invention is suitable for full-flow bench tests, suitable for different types of diesel engines, can effectively prolong the residence time of gas components in the plasma gas phase reaction zone, and ensure that the plasma active matrix and the harmful emission components of the diesel engine fully carry out chemical reactions; At the same time, combined with the particle sampling device, samples of particles before and after low-temperature plasma can be obtained at any time to analyze the changes in the morphology and composition of particles before and after low-temperature plasma, which provides favorable conditions for revealing the mechanism of low-temperature plasma reduction of particles. favorable conditions. The invention has compact structure and good applicability. 1) The angle between the exhaust pipe and the main exhaust pipe is 30°≤θ≤45°, the angle between the exhaust pipe and the main exhaust pipe is 30°≤θ≤45°, the angle is too low, There will be discharge interference between single low-temperature plasma generators, which will affect its discharge stability; if the angle is too large, it will cause greater resistance to the gas, increase the structure of the device, and reduce the economy. 2) The particle sampling system is easy to operate and easy to disassemble, which is convenient for real-time analysis of basic research on the impact of low-temperature plasma technology on particles. 3) The inlet and exhaust outlets are located on the same side and have an integrated structure. This structure can ensure the discharge stability and uniformity of a single plasma generator, so as to ensure the consistency and accuracy of experimental analysis. 4) The ratio of the distance L between the connection position of the total intake pipe and the intake pipe to the connection position of the total intake pipe and the particle sampling device A, and the inner diameter d of the total intake pipe is 1≤L/d≤2, and the ratio is too large Large, although it is easy to form turbulent vortices and collect more particles, but the internal resistance of the airflow in the intake and exhaust ports is relatively large, which limits the processing capacity of the system. If the ratio is too small, it is not easy to form a vortex vortex, the particles are blown out by the airflow, and it is not easy to collect the particles.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawings and examples.

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a schematic diagram of a single plasma generator of the present invention.

Fig. 3 is a schematic diagram of the structure of the low-temperature plasma discharge part of the present invention after the base and bracket are removed.

Fig. 4 is a schematic diagram of the low-temperature plasma discharge part of the present invention.

Fig. 5 is a particle sampling device of the present invention.

Fig. 6 is a schematic diagram of the main dimensions of the particle sampling device of the present invention.

Fig. 7 shows the flow field distribution of gas in the sampling device when the main dimension L/d of the particulate matter sampling device of the present invention is equal to 1.

Fig. 8 shows the flow field distribution of gas in the sampling device when the main dimension L/d of the particulate matter sampling device of the present invention is equal to 2.

In the figure, 1 main air intake pipe, 2 high voltage pole, 3 high voltage pole connecting rod, 4 plug A, 5 bracket A, 6 plasma generator, 7 air intake pipe, 8 valve A, 9 frosted sealing device A, 10 Particle sampling device A, 11 low voltage pole, 12 low voltage pole connecting rod, 13 lead wire, 14 particle sampling device B, 15 frosted sealing device B, 16 valve B, 17 exhaust pipe, 18 bracket B, 19 plug, 20 Total exhaust pipe, 21 floor.

Detailed ways

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

The invention is a novel low-temperature plasma generator cooperative particle sampling device for treating harmful emissions from diesel engines. During the test, first connect the high-voltage electrodes 2 and low-voltage electrodes 11 of three or more plasma generators in parallel by soldering or winding connecting rods, then connect the high-voltage electrodes to the variable-frequency and variable-voltage plasma power supply, and ground the low-voltage electrodes to Plasma is generated. The total exhaust pipe 1, the total exhaust pipe 20 are connected with the exhaust device with a silicone tube. The exhaust gas of the diesel engine is first connected to the main exhaust pipe 1, the valve A8 is rotated, the valve A8 is opened, and the particle sampling device A10 starts to obtain the particle sample. Particulate matter samples before low-temperature plasma action can be obtained; the gas is divided into three or more streams and enters the double dielectric barrier discharge low-temperature plasma generator respectively, and the gas is subjected to low-temperature plasma dielectric barrier discharge, and then the harmful exhaust gas first enters the main exhaust pipe 20 , by rotating the valve B16, the valve B16 is opened, and the particle sampling device B14 starts to obtain the particle sample. After waiting for a certain period of time, the particle sampling device B14 obtains the required particle sample, and then removes the particle sampling device B14 to obtain the particle sample after the low-temperature plasma action .

It can be seen from Fig. 6 that when L/d is equal to 1, the flow field distribution of the gas in the sampling device is generally uniform, and only a small turbulent vortex exists at the connection with the inlet pipe 7 . When L/d is equal to 2, there are larger and more turbulent eddies in the flow field of the gas in the sampling device. It can be seen from this that if the L/d ratio is too small, it is not easy to form a vortex vortex, the particles are blown out by the airflow, and it is not easy to collect the particles. If the ratio is too large, although it is easy to form turbulent vortices and collect more particles, the internal resistance of the airflow in the intake and exhaust ports is relatively large, which limits the processing capacity of the system.

The low-temperature plasma generator 6, the intake pipe 7, the exhaust pipe 17, the total intake pipe 1 and the total exhaust pipe 20 are integrally formed; between the particulate matter sampling device A10 and the total intake pipe 1, the particulate matter sampling device B14 It is a detachable device with the total exhaust pipe 20.

The angle between the intake pipe 7 and the total intake pipe 1 is 30°≤θ≤45°, the angle between the exhaust pipe 17 and the total exhaust pipe 20 is 30°≤θ≤45°; three or more The plasma generators are evenly arranged on the circumference around the total intake pipe 1 and the total exhaust pipe 20 .

The ratio of the distance L between the connection position of the total intake pipe 1 and the intake pipe 7 to the connection position between the total intake pipe 1 and the particulate matter sampling device A10, and the inner diameter d of the total intake pipe 1 is 1≤L/d≤2; The distance L between the connection position of the total exhaust pipe 20 and the exhaust pipe 17 and the connection position between the total exhaust pipe 20 and the particle sampling device B14 is in the range of 1≤L/ d≤2.

Claims (8)

1. A low-temperature plasma generator cooperative particle sampling device, characterized in that it includes a total air intake pipe (1), bracket A (5), three or more low-temperature plasma generators (6), and an air intake pipe (7) , particulate matter sampling device A (10), particulate matter sampling device B (14), exhaust pipe (17), bracket B (18), total exhaust pipe (20), base (21); the total intake pipe (1 ) and the total exhaust pipe (20) are circular tubes, and the axes are on the same straight line; one end of the total air intake pipe (1) is an air inlet, and the other end is provided with a particle sampling device A (10); the general exhaust One end of the air pipe (20) is an exhaust port, and the other end is provided with a low-temperature plasma generator (6), an air intake pipe (7), and a particle sampling device A (10); three or more plasma generators surround the main air intake pipe (1) and the total exhaust pipe (20) are evenly arranged on the circumference; the plasma generator consists of a high-voltage electrode (2), a plug A (4), a dielectric layer (6), a low-voltage electrode (11) and a head B (19), the medium layer (6) is a circular tube-shaped quartz glass tube, and the tube walls at both ends of the quartz glass tube are respectively provided with an air inlet pipe (7) and an exhaust pipe (17), and the air inlet pipe (7) It is connected to the side wall of the total air intake pipe (1), and the exhaust pipe (17) is connected to the side wall of the total exhaust pipe (20); the high voltage electrode (2) is a thin copper rod, placed In the quartz glass tube, the two ends of the high-voltage electrode (2) pass through two plugs respectively; the low-voltage electrode (11) is a constantan electrode, and the low-voltage electrode (11) is a round tube wrapped in quartz glass The outer side of the tube wall; the circular tube-shaped quartz glass tube is set on the bracket A (5) and the bracket B (18); the bracket A (5) and the bracket B (18) are fixed on the base (21); the said The material of bracket A (5), bracket B (18), base, plug A (4) and plug B (19) is polytetrafluoroethylene; the three or more low-temperature plasma generators (6) The high-voltage electrode (2) is connected by soldering or winding through the connecting rod (3), the low-voltage electrode (11) is connected by soldering or winding through the connecting rod (12), and grounded through the lead wire (13). 2. The low-temperature plasma generator cooperative particle sampling device according to claim 1, characterized in that the low-temperature plasma generator (6), the intake pipe (7), the exhaust pipe (17), and the total intake pipe (1) and the main exhaust pipe (20) are integrally formed; between the particle sampling device A (10) and the main air intake pipe (1), the particle sampling device B (14) and the main exhaust pipe (20) are Detachable unit. 3. The low-temperature plasma generator cooperative particle sampling device according to claim 1 or 2, characterized in that the angle between the inlet pipe (7) and the total inlet pipe (1) is 30°≤θ≤ 45°, the angle between the exhaust pipe (17) and the total exhaust pipe (20) is 30°≤θ≤45°. 4. The low-temperature plasma generator cooperative particle sampling device according to claim 3, characterized in that a valve A (8) is provided at one end of the main air intake pipe (1) connected to the particle sampling device A (10) , open the valve A (8), the gas flows into the particle sampling device A (10), and the particle sampling device A (10) obtains a particle sample; at the end of the main exhaust pipe (20) connected to the particle sampling device B (14) A valve B (16) is provided. When the valve B (16) is opened, the gas flows into the particle sampling device B (14), and the particle sampling device B (14) obtains a particle sample. 5. The low-temperature plasma generator cooperative particle sampling device according to claim 3, characterized in that, the connection position between the total intake pipe (1) and the intake pipe (7) is connected to the total intake pipe (1) and the particulate matter sampling The ratio of the distance L between the connection positions of the device A (10) to the inner diameter d of the total intake pipe (1) is in the range of 1≤L/d≤2. 6. The low-temperature plasma generator cooperative particle sampling device according to claim 3, characterized in that, the connecting position of the total exhaust pipe (20) and the exhaust pipe (17) is to the total exhaust pipe (20) The range of the distance L between the connection position of the particle sampling device B (14) and the inner diameter d of the total exhaust pipe (20) is 1≤L/d≤2. 7. The low-temperature plasma generator cooperative particulate matter sampling device according to claim 3, characterized in that, the particulate matter sampling device A (10) and the particulate matter sampling device B (14) are respectively connected to the main intake pipe (1) and the main The exhaust pipe (20) is connected through a frosted sealing device (9) and a frosted sealing device (15); the frosted sealing device (9) and the frosted sealing device (15) are sealed and connected through a frosted auxiliary gasket, or through a hinge Make a sealed connection. 8. A particulate matter sampling method utilizing the low-temperature plasma generator as claimed in claim 4 in conjunction with the particulate matter sampling device, wherein the particulate matter samples before the low-temperature plasma action and after the low-temperature plasma action are obtained at any time, the specific steps are: : Harmful exhaust gas first enters the main intake pipe (1), rotates the valve A (8), the valve A (8) opens, and the particle sampling device A (10) starts to collect particulate matter samples. After a certain period of time, the particle sampling device A (10) obtains all After the particle sample is required, remove the particle sampling device A (10) to obtain the particle sample before the low-temperature plasma; Harmful exhaust gas first enters the main exhaust pipe (20), and through the rotary valve B (16), the valve B (16) is opened, and the particle sampling device B (14) starts to obtain particulate matter samples, and the particle sampling device B (14) waits for a certain period of time After obtaining the required particle samples, remove the particle sampling device B (14) to obtain the particle samples after the low-temperature plasma action.