Plug-in low-temperature plasma array soil nitrogen fixation device

Abstract

According to the plug-in type low-temperature plasma array soil nitrogen fixation device, a plurality of low-temperature plasma reactors are inserted into soil in an array mode, a plurality of through holes are evenly distributed in the surface of a stainless steel pipe, the bottom of the stainless steel pipe is a circular truncated cone, and an opening is formed in the bottom of the stainless steel pipe; the stainless steel pipe is fixed at the lower end of the connecting firmware, the air pipe is arranged on the side edge of the connecting firmware, and the stainless steel electrode is fixed at the upper end of the connecting firmware; the metal electrode is arranged in the stainless steel tube as a high-voltage electrode and is fixed by the connecting firmware; the quartz tube is arranged in the stainless steel tube and sleeves the outer surface of the metal electrode to serve as a barrier medium; the power supply is connected with metal electrodes and stainless steel tubes; the air source is connected with the air pipe.

Description

Technical Field

[0001] The invention relates to the technical field of nitrogen fixation applications, in particular to an inserted low-temperature plasma array soil nitrogen fixation device. Background Art

[0002] Soil activated by atmospheric pressure non-thermal plasma has broad application prospects in chemical transformation, green agriculture, food safety, etc. Its soil fertility is closely related to the physical and chemical composition of the discharge plasma. The inorganic nitrogen component in the soil is the main source of nitrogen absorbed by plants, mainly ammonium salts and nitrates, accounting for about 1% to 2% of the nitrogen content in the soil. Plasma generates active substances in the gas phase, which directly act on or adsorb in the soil, further generating inorganic nitrides, bringing biological and chemical activity.

[0003] Therefore, the plasma soil nitrogen fixation process is a mass transfer process, and the active particles in the gas phase (especially short-lived particles) can only penetrate into the gas-solid interface to a very limited extent. Therefore, the key issue facing soil nitrogen fixation is to enhance the diffusion of active particles and gas-solid mass transfer.

[0004] The interface between plasma and soil plays an important role in the mass transfer and further reaction of reactive nitrogen and oxygen particles. The plug-in plasma generator provides a larger interaction surface area and a larger soil treatment scale, which can reduce the energy consumption during soil treatment.

[0005] The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0006] In view of the shortcomings or defects of the above-mentioned prior art, an insertable low-temperature plasma array soil nitrogen fixation device is provided, which can stably increase the inorganic nitrides in the soil without relying on any raw materials other than air, so that the plasma soil nitrogen fixation process can achieve high mass transfer efficiency and low energy consumption cost, while enhancing the activity of the activated soil and increasing the nitrogen content of poor soil to that of fertile soil.

[0007] The purpose of the present invention is achieved through the following technical solutions.

[0008] An insertable low-temperature plasma array soil nitrogen fixation device comprises:

[0009] A plurality of low-temperature plasma reactors are inserted into the soil in an array, wherein the low-temperature plasma reactors include:

[0010] The stainless steel pipe has multiple through holes evenly distributed on its surface, and the bottom is a truncated cone with an opening. The stainless steel pipe is inserted into the soil as a ground electrode.

[0011] The connecting fixture has a stainless steel pipe fixed at the lower end, an air pipe provided on the side, and a stainless steel electrode fixed at the upper end;

[0012] A metal electrode, which is placed in the stainless steel tube as a high-voltage electrode and fixed via the connecting piece;

[0013] A quartz tube, which is placed inside the stainless steel tube and sleeved on the outer surface of the metal electrode as a blocking medium;

[0014] A power source, which connects the metal electrodes and the stainless steel tube;

[0015] An air source is connected to the air pipe.

[0016] In the insertable low-temperature plasma array soil nitrogen fixation device, the through holes are evenly distributed around the tube wall in the transverse direction and are also evenly distributed along the tube wall in the longitudinal direction, and the through holes vertically penetrate the tube wall.

[0017] In the insertable low-temperature plasma array soil nitrogen fixation device, the diameter of the through hole is 1 mm, and at least 6 through holes are distributed laterally around the tube wall.

[0018] In the insertable low-temperature plasma array soil nitrogen fixation device, the connecting fixture is a T-shaped variable diameter three-way joint, and the three-side interfaces respectively match the diameters of the stainless steel pipe, the metal electrode and the air pipe, and the connecting fixture is made of insulating material.

[0019] In the insertable low-temperature plasma array soil nitrogen fixation device, the connecting fixture is made of polytetrafluoroethylene.

[0020] In the insertable low-temperature plasma array soil nitrogen fixation device, threaded structures are formed on the three side interfaces, and at least one interface is placed inside a nut and sleeved on the outside of a stainless steel pipe, and is screwed into the stainless steel pipe through the nut to ensure air tightness.

[0021] In the insertable low-temperature plasma array soil nitrogen fixation device, the metal electrode is a finely ground solid round rod with uniform thickness.

[0022] In the insertable low-temperature plasma array soil nitrogen fixation device, the metal electrode is connected to the positive pole of the power supply through a wire winding and a metal clip, and the stainless steel tube is connected to the negative pole of the power supply through a wire winding and a metal clip.

[0023] In the insertable low-temperature plasma array soil nitrogen fixation device, the inner diameter of the quartz tube is adapted to the outer diameter of the metal electrode to fix the quartz tube.

[0024] In the plug-in low-temperature plasma array soil nitrogen fixation device, the power supply is an alternating power supply with a discharge voltage of at least 7 kV and a discharge frequency of at least 30 kHz.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The inorganic nitride produced by the present invention is produced only by the discharge device, does not require fossil fuels, and does not emit a large amount of greenhouse gases; when the same flow rate of gas is introduced, the initial discharge power of the reactor is only 6W, and about 30.5μmol of nitrate is stably produced in each gram of soil during discharge, and the energy consumption can be as low as 0.49 kWh / mmol. The entire device is compatible with renewable energy sources such as solar energy and wind energy, and is clean and environmentally friendly. It can be directly inserted into the soil for use without manual filling operation. The structure is simple and easy to operate, and no additional manpower and material costs are required. It only needs to be directly inserted into the soil to increase the nitrogen content of the soil through air discharge. The activated gas may further modify the soil and solve the problems of soil compaction and airtightness and soil acidification. The scale of soil treatment is large, and array operation can be realized. A single reactor can process more than 400g of soil at a power of 30W, and the number of discharge units can be flexibly changed to realize array operation. The discharge is uniform and stable. The outer shell is a grounded stainless steel tube instead of a quartz tube, the single-layer dielectric reduces the starting discharge voltage and power, and the central electrode structure realizes uniform dielectric barrier discharge.

[0027] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to achieve the extent that those skilled in the art can implement it according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0029] In the attached picture:

[0030] Figure 1 It is a schematic diagram of the structure of the plasma reactor in the present invention;

[0031] Figure 2It is a schematic diagram of the array operation of the device of the present invention;

[0032] Figure 3 This is a statistical diagram showing the variation of the increase in nitrate nitrogen produced by the device of the present invention with soil depth and soil moisture.

[0033] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0035] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0036] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0037] For a better understanding, Figures 1 to 3 As shown, an insertable low-temperature plasma array soil nitrogen fixation device comprises:

[0038] A plurality of low-temperature plasma reactors are inserted into the soil in an array, wherein the low-temperature plasma reactors include:

[0039] The stainless steel pipe has multiple through holes evenly distributed on its surface, and the bottom is a truncated cone with an opening. The stainless steel pipe is inserted into the soil as a ground electrode.

[0040] The connecting fixture has a stainless steel pipe fixed at the lower end, an air pipe provided on the side, and a stainless steel electrode fixed at the upper end;

[0041] A metal electrode, which is placed in the stainless steel tube as a high-voltage electrode and fixed via the connecting piece;

[0042] A quartz tube, which is placed inside the stainless steel tube and sleeved on the outer surface of the metal electrode as a blocking medium;

[0043] A power source, which connects the metal electrodes and the stainless steel tube;

[0044] An air source is connected to the air pipe.

[0045] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the through holes are evenly distributed around the tube wall in the transverse direction and also evenly distributed along the tube wall in the longitudinal direction, and the through holes vertically penetrate the tube wall.

[0046] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the diameter of the through hole is 1 mm, and at least 6 through holes are distributed laterally around the tube wall.

[0047] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the connecting fixture is a T-shaped variable diameter three-way joint, and the three-side interfaces respectively match the diameters of the stainless steel pipe, the metal electrode and the air pipe, and the connecting fixture is made of insulating material.

[0048] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the connecting piece is made of polytetrafluoroethylene.

[0049] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, a threaded structure is formed on the three-side interfaces, and at least one interface is placed inside a nut and sleeved on the outside of a stainless steel pipe, and is screwed into the stainless steel pipe through the nut to ensure air tightness.

[0050] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the metal electrode is a finely ground solid round rod with uniform thickness.

[0051] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the metal electrode is connected to the positive pole of the power supply through a wire winding and a metal clip, and the stainless steel tube is connected to the negative pole of the power supply through a wire winding and a metal clip.

[0052] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the inner diameter of the quartz tube is adapted to the outer diameter of the metal electrode to fix the quartz tube.

[0053] In a preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the power supply is an alternating power supply with a discharge voltage of at least 7 kV and a discharge frequency of at least 30 kHz.

[0054] In one embodiment, Figure 1As shown in the figure, there is a millimeter hole on the surface of the stainless steel tube, and the hole diameter is 1mm, and the activated gas escapes from this hole. In the present invention, there are at least 6 millimeter holes, which can be selected to face any direction and are not limited to those shown in the figure; in another example of the present invention, the number of holes is 60, which are evenly distributed on the surface of the stainless steel tube. Figure 1 As shown in the figure, the upper interface of the connecting fixture is connected to the gas pipeline, and the left side is connected to the quartz tube. The three side interfaces of the connecting fixture are all the cooperation of bolts and threaded structures. The connecting fixture should be made of insulating material. In a preferred embodiment of the present invention, the connecting fixture is made of polytetrafluoroethylene. The good air tightness of the connecting fixture is achieved by the cooperation of the ferrule and the bolt structure.

[0055] exist Figure 1 As shown in , the gas introduced by the gas pipeline can be external gas or a gas cylinder, and a gas mass flow controller is required to control the flow rate to be stable. In a preferred embodiment of the present invention, the gas flow rate is controlled at 1L / min.

[0056] The metal electrodes in this device can be made of common metals, including but not limited to 304 stainless steel, tungsten steel, etc. It should be noted that the metal electrodes should have a smooth surface to ensure uniform and stable DBD discharge and extend its service life.

[0057] In this device, the metal electrode and the stainless steel tube are connected to provide a power source for the discharge voltage without any restrictions. In a preferred embodiment of the present invention, a high-frequency AC power source is used, and its voltage should be above 7kV and the frequency should be above 30kHz.

[0058] The practical effects of a specific embodiment of the present invention are listed below:

[0059] According to the above specific implementation method, the input gas is air, and when the gas flow rate is 1L / min, the plasma activated gas directly acts on the soil in the tube, or diffuses from the small holes to the outside of the tube, achieving in-situ soil nitrogen fixation. Figure 3 The figure shows the statistics of the increase of nitrate nitrogen with soil depth under different soil moisture. The increase of nitrate nitrogen with soil depth shows a volcanic curve. The nitrogen fixation effect is best at 13% soil moisture, and the increase of nitrate nitrogen at 4cm is the highest, about 427μg. N ·g -1 soil , the increase in nitrate nitrogen in deeper or shallower soils decreases.

[0060] In one embodiment, the gas length between the quartz tube and the stainless steel tube is 1 mm, the thickness of the stainless steel tube is 2 mm, the radius of the metal electrode is 3.5 mm, and the thickness of the quartz tube is 0.5 mm.

[0061] In one embodiment, in order to treat the soil uniformly and avoid partial discharge, the power source is selected to have a power of at least 30W.

[0062] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0063] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. An insertable low-temperature plasma array soil nitrogen fixation device, characterized in that: These include, A plurality of low-temperature plasma reactors are inserted into the soil in an array, wherein the low-temperature plasma reactors include: The stainless steel pipe has multiple through holes on its surface. The stainless steel pipe is inserted into the soil as a ground electrode. A connecting fixture, the lower end of which is fixed with a stainless steel pipe and the side is provided with an air pipe; A metal electrode, which is placed in the stainless steel tube as a high-voltage electrode and fixed via the connecting piece; A quartz tube, which is placed inside the stainless steel tube and sleeved on the outer surface of the metal electrode as a blocking medium; A power source, which connects the metal electrodes and the stainless steel tube; An air source is connected to the air pipe.

2. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: Preferably, the through hole vertically penetrates the tube wall.

3. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: The diameter of the through hole is 1 mm.

4. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: The connecting fixture is a T-shaped variable diameter three-way joint.

5. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 4, characterized in that: The connecting piece is made of polytetrafluoroethylene.

6. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: The metal electrode is a finely ground solid round rod with uniform thickness.

7. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: The metal electrode is connected to the positive electrode of the power source through a wire winding and a metal clip, and the stainless steel tube is connected to the negative electrode of the power source through a wire winding and a metal clip.

8. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: The inner diameter of the quartz tube is adapted to the outer diameter of the metal electrode to fix the quartz tube.

9. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: The power source is an alternating current source.

10. The insertable low-temperature plasma array soil nitrogen fixation device according to claim 1, characterized in that: The discharge voltage shall be at least 7 kV and the discharge frequency shall be at least 30 kHz.

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