Low-temperature plasma HgCl2 continuous generation device

Abstract

The application discloses a low-temperature plasma HgCl2 continuous generation device, which comprises a gas mixing chamber, a plasma reaction zone and a temperature reducing device. Gases are uniformly mixed in the gas mixing chamber. The first end of the plasma reaction zone is connected with the gas mixing chamber through a gas inlet pipe. The second end of the plasma reaction zone is connected with a gas outlet pipe. The plasma reaction zone comprises an inner medium and an outer medium. An annular reaction zone is formed between the inner medium and the outer medium. The gas in the gas mixing chamber enters the annular reaction zone. The temperature reducing device is used for reducing the temperature of the plasma reaction zone. The low-temperature plasma HgCl2 continuous generation device has the advantages of low energy consumption and stable reaction.

Description

Technical Field

[0001] This invention relates to the technical field of online monitoring of mercury pollutants from coal combustion, and in particular to a low-temperature plasma HgCl2 continuous generation device. Background Technology

[0002] Coal remains China's primary energy source, boasting high utilization value and wide applications. Industrial applications include power plant generation and boiler combustion for heating. However, coal combustion also produces a variety of pollutants, among which mercury and its compounds are highly toxic, exhibiting bioaccumulation and long-distance migration in the environment. Mercury can enter the body through inhalation, skin absorption, or ingestion, harming the central nervous system. Sources of mercury pollution primarily include natural releases, anthropogenic emissions, and secondary releases, with anthropogenic emissions accounting for approximately three-quarters. Coal-fired power plants are the world's largest anthropogenic source of mercury emissions.

[0003] Currently, the main methods for detecting mercury emission concentrations from coal-fired power plants include wet chemical methods (OHM), EPA-30B methods, and online mercury monitoring systems (Hg-CEMS). The first two methods are offline measurement methods, while the latter is an online measurement method. Currently, atomic absorption spectroscopy and atomic fluorescence spectroscopy for mercury detection can only determine Hg0; the determination of Hg2+ requires its conversion to Hg0 for indirect measurement. The generation of Hg2+ standard gas is one of the core technologies for accurate Hg2+ determination. Currently, commercially available Hg2+ standard gas generation technologies typically utilize a chlorine-containing gas source to react and obtain Hg2+ standard gas under high-temperature conditions. Using chlorine as the Cl source results in a reversible reaction at high temperatures; using HCl as the Cl source results in a high reaction temperature and a narrow temperature window. Both methods require the use of catalysts, but catalysts deactivate after a certain period of use, thus requiring periodic replacement. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of the present invention propose a low-temperature plasma HgCl2 continuous generation device, which has the advantages of low energy consumption and stable reaction.

[0005] According to an embodiment of the present invention, a low-temperature plasma HgCl2 continuous generator includes a mixing chamber, a plasma reaction zone, and a cooling device. Gases are uniformly mixed within the mixing chamber. A first end of the plasma reaction zone is connected to the mixing chamber via an inlet pipe, and a second end of the plasma reaction zone is connected to an outlet pipe. The plasma reaction zone includes an inner medium and an outer medium, forming an annular reaction zone between the inner and outer medium. Gases from the mixing chamber enter the annular reaction zone. The cooling device is used to reduce the temperature of the plasma reaction zone.

[0006] The low-temperature plasma HgCl2 continuous generator according to embodiments of the present invention has the advantages of low energy consumption and stable reaction.

[0007] In some embodiments, the mixing chamber has a first gas distribution pipe and a second gas distribution pipe, the first gas distribution pipe delivering Hg and the second gas distribution pipe delivering a Cl source.

[0008] In some embodiments, the depth to which the first gas distribution pipe enters the mixing chamber is greater than the depth to which the second gas distribution pipe enters the mixing chamber.

[0009] In some embodiments, there are two second gas distribution pipes, which are symmetrical about the first gas distribution pipe.

[0010] In some embodiments, a metal conductor mesh screen is provided at the first end of the plasma reaction zone.

[0011] In some embodiments, the distance between the inner medium and the outer medium is 0–8 mm, and the length of the plasma reaction zone is 0–1000 mm.

[0012] In some embodiments, the inner wall surface of the outer medium is provided with an internal thread structure, and the outer wall surface of the inner medium is provided with an external thread structure, wherein the internal thread structure and the external thread structure are positive spiral threads.

[0013] In some embodiments, an isolation element is also included, which is disposed below the intake pipe and above the exhaust pipe.

[0014] In some embodiments, the cooling device includes a temperature measuring device and a cooling fan, the cooling fan being electrically connected to the temperature measuring device, the cooling fan blowing air into the plasma reaction zone, and the temperature measuring device detecting the temperature at the end of the plasma reaction zone away from the mixing chamber.

[0015] In some embodiments, when the Cl source is hydrogen chloride or chlorine, the molar ratio of mercury vapor to hydrogen chloride is greater than 1:100; when the Cl source is a mixture of hydrogen chloride and chlorine, the molar ratio of mercury vapor to hydrogen chloride and chlorine is greater than 1:100, and the molar ratio of chlorine to hydrogen chloride is 1:10 to 1:50. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a low-temperature plasma HgCl2 continuous generator according to an embodiment of the present invention.

[0017] Figure 2 This is an enlarged schematic diagram of the cross-section along the AA direction of the low-temperature plasma HgCl2 continuous generator according to an embodiment of the present invention.

[0018] Figure 3 This is an enlarged schematic diagram of the cross-section along the BB direction of the low-temperature plasma HgCl2 continuous generator according to an embodiment of the present invention.

[0019] Figure 4 This is a comparison diagram of the HgCl2 generation rate and the circumferential gap thickness of the low-temperature plasma HgCl2 continuous generator according to an embodiment of the present invention.

[0020] Reference numerals: 1. Mixing chamber; 2. Inlet pipe; 3. Internal medium; 4. External medium; 5. Screen; 6. Isolation component; 7. First gas distribution pipe; 8. Second gas distribution pipe; 9. Outlet pipe; 10. Temperature measuring device; 11. Cooling fan; 12. Reaction zone. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] According to embodiments of the present invention, a low-temperature plasma HgCl2 continuous generation device, such as... Figures 1 to 4As shown, the low-temperature plasma HgCl2 continuous generation device includes a mixing chamber, a plasma reaction zone, and a cooling device. The gas is uniformly mixed within the mixing chamber. The first end of the plasma reaction zone is connected to the mixing chamber via an inlet pipe, and the second end is connected to an outlet pipe. The plasma reaction zone includes an inner medium and an outer medium, forming an annular reaction zone. Gas from the mixing chamber enters the annular reaction zone. The cooling device is used to lower the temperature of the plasma reaction zone. The inner and outer media are made of quartz or Al2O3 ceramic materials. The mixing chamber is made of quartz material. Mercury vapor and the Cl source are mixed within the mixing chamber. When the cooling device detects that the temperature of the plasma reaction zone exceeds a preset temperature, it automatically activates and lowers the temperature of the plasma reaction zone. Using plasma discharge to generate plasma results in a low-temperature chlorination reaction, low equipment energy consumption, and no catalyst deactivation during the reaction. The cooling device reduces the impact of temperature on reaction stability. This invention proposes a method for generating low-temperature plasma using dielectric barrier discharge to perform a chlorination reaction, achieving continuous and stable generation of HgCl2. This provides new ideas for the development of online monitoring technologies and devices for mercury in air pollutants emitted by my country's power and non-power industries.

[0023] The low-temperature plasma HgCl2 continuous generator according to embodiments of the present invention has the advantages of low energy consumption and stable reaction.

[0024] In some embodiments, such as Figure 1 and Figure 3 As shown, the mixing chamber has a first gas distribution pipe and a second gas distribution pipe. The first gas distribution pipe delivers Hg, and the second gas distribution pipe delivers Cl source.

[0025] Specifically, the first and second gas distribution pipes are made of quartz, and they deliver Hg and Cl sources, which are then uniformly mixed in the mixing chamber. The Cl source uses Cl2 and HCl gas; the mercury source uses Hg. 0 Mercury vapor is used as the mercury source, while an inert gas, such as N2 or Ar, is used as the carrier gas.

[0026] In some embodiments, such as Figure 1 As shown, the depth to which the first gas distribution pipe enters the mixing chamber is greater than the depth to which the second gas distribution pipe enters the mixing chamber.

[0027] Specifically, the first gas distribution pipe enters the mixing chamber at a greater depth than the second gas distribution pipe, which enables the mercury source and chlorine source to be positioned differently, resulting in more uniform gas mixing.

[0028] In some embodiments, such as Figure 1 and Figure 3 As shown, there are two second gas distribution pipes, which are symmetrical about the first gas distribution pipe.

[0029] Specifically, the first gas distribution pipe is located in the center of the two second gas distribution pipes, which enables the chlorine source to be fully mixed with the mercury vapor.

[0030] In some embodiments, such as Figure 1 As shown, a metal conductor mesh screen is provided at the first end of the plasma reaction zone.

[0031] Specifically, the metal conductor mesh screen can filter the gas entering the reaction zone and intercept large particulate impurities in the carrier gas.

[0032] In some embodiments, such as Figure 1 and Figure 2 As shown, the distance between the inner and outer media is 0–8 mm, and the length of the plasma reaction zone is 0–1000 mm.

[0033] Specifically, the distance between the inner and outer media determines the cross-sectional area of ​​the annular reaction zone. The length and cross-sectional area of ​​the plasma reaction zone should ensure that the specific energy density (SED) value is higher than the energy required for bond breaking of the chlorine source.

[0034] In some embodiments, the inner wall surface of the outer medium is provided with an internal thread structure, and the outer wall surface of the inner medium is provided with an external thread structure. The internal thread structure and the external thread structure are positive spiral threads.

[0035] Specifically, the use of a threaded structure between the inner and outer media can increase the dielectric barrier discharge intensity, ensuring the reaction intensity of the plasma reaction zone. The threaded structure can provide discharge tips, thereby increasing the local discharge intensity and reaction efficiency.

[0036] In some embodiments, such as Figure 1 As shown, it also includes an isolation component, which is located below the intake pipe and above the exhaust pipe.

[0037] Specifically, the isolation components are made of insulating and corrosion-resistant materials. There are two isolation components, which are installed in the inlet pipe and the outlet pipe to isolate the plasma reaction zone from the outside world and ensure the stability of the reaction.

[0038] In some embodiments, such as Figure 1 As shown, the cooling device includes a temperature measuring device and a cooling fan. The cooling fan is electrically connected to the temperature measuring device. The cooling fan blows air into the reaction zone, and the temperature measuring device detects the temperature at the end of the plasma reaction zone away from the mixing chamber.

[0039] Specifically, the temperature measuring device can be an infrared temperature measuring device, and the cooling fan can be automatically controlled by an automatic temperature control system. The infrared temperature measuring device measures the temperature of the upper part of the reaction zone in real time. According to the measurement results of the infrared temperature measuring device, when the temperature exceeds 140 degrees Celsius, the cooling fan is automatically turned on to cool the plasma reaction zone.

[0040] In some embodiments, when the Cl source is hydrogen chloride or chlorine, the molar ratio of mercury vapor to hydrogen chloride is greater than 1:100; when the Cl source is a mixture of hydrogen chloride and chlorine, the molar ratio of mercury vapor to hydrogen chloride and chlorine is greater than 1:100; and the molar ratio of chlorine to hydrogen chloride is 1:10 to 1:50.

[0041] Specifically, using Cl2, HCl, or a mixture of both as the Cl source increases the range of Cl source choices and facilitates the provision of oxidized mercury at the appropriate temperature.

[0042] Example 1: This invention provides a low-temperature plasma HgCl2 continuous generator. Both the inner and outer media thicknesses are 2.5 mm, the reaction zone length is 18 mm, and the annular gap thickness in the reaction zone can be 1.5 mm, 2.5 mm, or 3.5 mm. The Cl source is N2 and 20 ppm HCl, and the total gas flow rate is 2 L / min. Nitrogen is used as the inert gas. The media material is Al2O3 ceramic, and the reaction zone isolation element is a rubber ring. The automatic temperature control device is set to automatically turn on the fan when the temperature exceeds 140 degrees Celsius. HCl enters the mixing chamber through two peripheral secondary gas distribution pipes under nitrogen supply, while HgCl2... 0 Nitrogen gas is supplied through the first gas distribution pipe in the middle, entering the mixing chamber. The three gases mix in the mixing chamber, during which a partial oxidation reaction occurs to generate some HgCl2. The gas then enters the plasma reaction zone, where plasma is generated through dielectric barrier discharge. Within the reaction zone, the gas undergoes a chlorination reaction to generate HgCl2. The reacted gas flows out through the outlet pipe for use. During the reaction, an infrared thermometer measures the temperature of the upper part of the reaction zone in real time. Based on the temperature feedback, an automatic temperature control system from Huoyu Instrument Factory is used for control. When the temperature exceeds 140 degrees Celsius, the cooling fan automatically turns on to cool the device. The experimental results are shown in the figure. Figure 4 As shown.

[0043] Example 2: This invention provides a low-temperature plasma HgCl2 continuous generation device, where both the inner and outer media thicknesses are 2.5 mm, the reaction zone length is 180 mm, the annular slit thickness of the reaction zone is 3.5 mm, and the Cl source is N. 2、 The reaction mixture consists of 1.25 ppm Cl₂ and 50 ppm HCl, with a total gas flow rate of 2 L / min. Nitrogen is used as the inert gas. Al₂O₃ ceramic is used as the reaction medium, and rubber rings are used to isolate the reaction zone. An automatic temperature control system activates the fan when the temperature exceeds 140 degrees Celsius. HCl enters the mixing chamber via two external secondary gas distribution pipes, supplied by nitrogen. Hg 0Nitrogen gas is supplied through the first gas distribution pipe in the middle, entering the mixing chamber. The three gases mix in the mixing chamber, during which a partial oxidation reaction occurs to generate some HgCl2. The gas then enters the plasma reaction zone, where plasma is generated through dielectric barrier discharge. Within the reaction zone, the gas undergoes a chlorination reaction to generate HgCl2. The reacted gas flows out through the outlet pipe for use. During the reaction, an infrared thermometer measures the temperature of the upper part of the reaction zone in real time. Based on the temperature feedback, an automatic temperature control system from Huoyu Instrument Factory is used for control. When the temperature exceeds 140 degrees Celsius, the cooling fan automatically turns on to cool the device.

[0044] Under the experimental conditions of the above embodiments, the chlorination reaction efficiency (above 90%) and the degree of corrosion of the reaction zone are controlled to a certain extent. It can achieve a high continuous and stable HgCl2 generation rate under low temperature conditions, and has the advantages of low energy consumption and small equipment size.

[0045] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0049] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0050] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A low-temperature plasma HgCl2 continuous generation device, characterized in that, include: The gas mixing chamber is where the gas is mixed evenly. The plasma reaction zone has a first end connected to the mixing chamber via an inlet pipe and a second end connected to an outlet pipe. The plasma reaction zone includes an inner medium and an outer medium, and an annular reaction zone is formed between the inner medium and the outer medium. The gas from the mixing chamber enters the annular reaction zone. A cooling device, wherein the cooling device is used to reduce the temperature of the plasma reaction zone; The mixing chamber has a first gas distribution pipe and a second gas distribution pipe, the first gas distribution pipe delivers Hg, and the second gas distribution pipe delivers Cl source; The first gas distribution pipe enters the mixing chamber at a greater depth than the second gas distribution pipe, which enables the positional difference between the Hg source and the Cl source, resulting in more uniform gas mixing.

2. The low-temperature plasma HgCl2 continuous generation device according to claim 1, characterized in that, There are two second gas distribution pipes, which are symmetrical about the first gas distribution pipe.

3. The low-temperature plasma HgCl2 continuous generation device according to claim 1, characterized in that, The first end of the plasma reaction zone is equipped with a metal conductor mesh screen.

4. The low-temperature plasma HgCl2 continuous generation device according to claim 1, characterized in that, The distance between the inner medium and the outer medium is 1.5 to 8 mm, and the length of the plasma reaction zone is 18 to 1000 mm.

5. The low-temperature plasma HgCl2 continuous generation device according to claim 1, characterized in that, The inner wall of the outer medium is provided with an internal thread structure, and the outer wall of the inner medium is provided with an external thread structure. The internal thread structure and the external thread structure are positive spiral threads.

6. The low-temperature plasma HgCl2 continuous generation device according to claim 1, characterized in that, It also includes an isolation element disposed below the intake pipe and above the exhaust pipe.

7. The low-temperature plasma HgCl2 continuous generation device according to claim 1, characterized in that, The cooling device includes a temperature measuring device and a cooling fan. The cooling fan is electrically connected to the temperature measuring device and blows air into the plasma reaction zone. The temperature measuring device detects the temperature at the end of the plasma reaction zone away from the mixing chamber.

8. The low-temperature plasma HgCl2 continuous generation device according to claim 1, characterized in that, When the Cl source is hydrogen chloride or chlorine, the molar ratio of mercury vapor to hydrogen chloride is greater than 1:

100. When the Cl source is a mixture of hydrogen chloride and chlorine, the molar ratio of mercury vapor to hydrogen chloride and chlorine is greater than 1:100, and the molar ratio of chlorine to hydrogen chloride is 1:10 to 1:50.

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