Insertable low temperature plasma array soil nitrogen fixation device

Abstract

Disclosed is a plug-in type low-temperature plasma array soil nitrogen fixation device, in which a plurality of low-temperature plasma reactors are arrayed and inserted into soil, a stainless steel pipe has a plurality of through holes uniformly distributed on the surface of the pipe, the bottom of the pipe is a circular table and is provided with an opening, the stainless steel pipe is inserted into the soil as a ground electrode, a connecting fastener is used to fix the lower end of the stainless steel pipe, a gas pipe is arranged on the side edge, a stainless steel electrode is fixed to the upper end, a metal electrode is arranged in the stainless steel pipe as a high-voltage electrode and is fixed via the connecting fastener, a quartz pipe is arranged in the stainless steel pipe and is sleeved on the outer surface of the metal electrode as a barrier medium, a power source is connected to the metal electrode and the stainless steel pipe, and a gas source is connected to the gas pipe.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nitrogen fixation application, and particularly relates to an inserted low-temperature plasma array soil nitrogen fixation device. BACKGROUND

[0002] Atmospheric pressure non-thermal plasma activation treatment of soil has broad application prospects in chemical conversion, green agriculture, food safety and the like, and soil fertility is closely related to physical and chemical components of discharge plasma. Inorganic nitrogen components in soil are main nitrogen sources absorbed by plants, mainly ammonium salt and nitrate, accounting for about 1% to 2% of nitrogen content in soil. Plasma generates active substances in gas phase, which directly acts on or is adsorbed in soil to further generate inorganic nitrogen compounds, bringing biological and chemical activity.

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

[0004] The interface between plasma and soil plays an important role in mass transfer and further reaction of active nitrogen oxide particles. The inserted plasma generator provides a larger interaction surface area, and at the same time, a larger scale of soil is treated, which can reduce energy consumption in the soil treatment process.

[0005] The information disclosed in the background section merely serves to enhance the understanding of the background of the present application, and therefore can contain information that does not constitute prior art that is already known to those of ordinary skill in the art. SUMMARY

[0006] In view of the deficiencies or defects of the prior art, an inserted low-temperature plasma array soil nitrogen fixation device is provided, which can stably increase inorganic nitrogen compounds in soil without relying on any raw material other than air, so that the plasma soil nitrogen fixation process reaches high mass transfer efficiency and low energy consumption cost, and at the same time, the activated soil activity is enhanced, and the nitrogen content of infertile soil is increased to the nitrogen content of fertile soil.

[0007] The object of the present application is achieved by the following technical solutions.

[0008] An inserted low-temperature plasma array soil nitrogen fixation device comprises,

[0009] a plurality of low-temperature plasma reactors which are arrayed and inserted into soil, the low-temperature plasma reactors comprising,

[0010] a stainless steel pipe which is uniformly provided with a plurality of through holes on the surface, has a circular truncated cone bottom and is provided with an opening, and is inserted into soil as a ground electrode,

[0011] a connecting fixture, a lower end of which is fixed to the stainless steel tube, and a side edge of which is provided with an air tube, and an upper end of which is fixed to the stainless steel electrode;

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

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

[0014] a power supply, which is connected to the metal electrode and the stainless steel tube;

[0015] an air source, which is connected to the air tube.

[0016] In the plug-in type low-temperature plasma array soil nitrogen fixation device, the through holes are uniformly distributed transversely around the tube wall and longitudinally along the tube wall, and the through holes vertically penetrate the tube wall.

[0017] In the plug-in type low-temperature plasma array soil nitrogen fixation device, the aperture of the through hole is 1 mm, and at least six through holes are transversely distributed around the tube wall.

[0018] In the plug-in type low-temperature plasma array soil nitrogen fixation device, the connecting fixture is a T-shaped variable-diameter tee joint, three side interfaces of which are matched with the diameters of the stainless steel tube, the metal electrode and the air tube respectively, and the connecting fixture is made of an insulating material.

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

[0020] In the plug-in type low-temperature plasma array soil nitrogen fixation device, a threaded structure is formed on the three side interfaces, at least one interface is placed in the inner part of a nut and is sleeved on the outside of the stainless steel tube, and the nut is screwed into the stainless steel tube to ensure air tightness.

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

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

[0023] In the plug-in type 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] The power supply is an alternating power supply, and the discharge voltage is at least 7kV, and the discharge frequency is at least 30kHz.

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

[0026] The inorganic nitride produced by the present application is only generated by the discharge device, does not require fossil fuels, and does not emit a large amount of greenhouse gases; when the same flow of gas is introduced, the initial discharge power of the reactor is only 6W, and about 30.5umol of nitrate is stably generated in each gram of soil during discharge, and the energy consumption can be as low as 0.49kWh / mmol. The entire device is compatible with solar energy, wind energy and other renewable energy sources, and is clean and environmentally friendly. It can be directly inserted into the soil for use without manual loading operation. The structure is simple and convenient to operate, and no additional manpower and material resources are required. Only by directly inserting into the soil through air discharge can the nitrogen content of the soil be improved, and the soil can be further modified by activation gas to solve the problems of soil hardening and poor air permeability, and soil acidification. The scale of the treated soil is large, and array operation can be realized. A single reactor can treat 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 shell is a grounded stainless steel pipe instead of a quartz pipe, a single layer of medium reduces the initial discharge voltage and power, and the center electrode structure realizes uniform dielectric barrier discharge.

[0027] The description is only a summary of the technical solutions of the present application, in order to make the technical means of the present application clearer and more understandable, to the extent that the contents of the description can be implemented by those skilled in the art, and in order to make the said and other purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0028] Various other advantages and benefits of the present application will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are for purposes of illustration only and are not to be construed as limiting the application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those of ordinary skill in the art. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0029] In the drawings:

[0030] Figure 1 The structure of the plasma reactor in the present application is shown in the figure;

[0031] Figure 2An array working schematic of the device of the present application;

[0032] Figure 3 A statistical diagram showing the change of the increased amount of nitrate nitrogen generated by the device of the present application with the soil depth and soil humidity.

[0033] The present application will be further explained in conjunction with the accompanying drawings and examples. DETAILED DESCRIPTION

[0034] The specific embodiments of the present application will be described in conjunction with the accompanying drawings. Although specific embodiments of the present application are shown in the drawings, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present application can be more thoroughly understood and so that the scope of the present application can be completely conveyed to those skilled in the art.

[0035] It should be noted that certain terms are used throughout the present specification and claims which have particular meanings as set forth below. Those skilled in the art will understand that not all terms are used as set forth below, but have meanings that are clear from the context in which they are used. The present specification and claims are not to be limited by the terms as set forth below, but are to be interpreted in light of the general principles set forth in the present specification and claims.

[0036] For the convenience of understanding the embodiments of the present application, the following will be further explained and described with reference to the accompanying drawings in conjunction with several specific embodiments, and each of the accompanying drawings does not constitute a limitation to the embodiments of the present application.

[0037] For a better understanding, Figures 1 to 3 as shown, an inserted low-temperature plasma array soil nitrogen fixation device includes,

[0038] a plurality of low-temperature plasma reactors which are arrayed and inserted into the soil, the low-temperature plasma reactors including,

[0039] a stainless steel tube having a plurality of through-holes uniformly distributed on the surface thereof, a bottom being a circular truncated cone and being provided with an opening, the stainless steel tube being inserted into the soil as a ground electrode,

[0040] a connecting fixture having a lower end fixed to the stainless steel tube, a side edge provided with an air pipe, and an upper end fixed to the stainless steel electrode;

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

[0042] a quartz tube is placed in the stainless steel tube and is sleeved on the outer surface of the metal electrode as a barrier medium;

[0043] a power source is connected to the metal electrode and the stainless steel tube;

[0044] a gas source is connected to the gas tube.

[0045] In the preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the through holes are uniformly distributed transversely around the tube wall and longitudinally along the tube wall, and the through holes vertically penetrate the tube wall.

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

[0047] In the preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the connecting fixture is a T-shaped variable-diameter tee joint, and the three side interfaces are matched with the diameters of the stainless steel tube, the metal electrode, and the gas tube, respectively. The connecting fixture is made of an insulating material.

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

[0049] In the 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 sleeved in a nut and outside the stainless steel tube, and the nut is screwed into the stainless steel tube to ensure airtightness.

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

[0051] In the 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 source through wire winding or a metal clamp, and the stainless steel tube is connected to the negative pole of the power source through wire winding or a metal clamp.

[0052] In the 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 the preferred embodiment of the insertable low-temperature plasma array soil nitrogen fixation device, the power source is an alternating power source, the discharge voltage is at least 7 kV, and the discharge frequency is at least 30 kHz.

[0054] In one embodiment, in Figure 1As shown, the stainless steel tube surface has a 1mm diameter hole through which activation gas escapes. In this invention, there are at least six 1mm holes, which can be oriented in any direction and are not limited to those shown in the figure; in another embodiment of the invention, the number of holes is 60, evenly distributed on the surface of the stainless steel tube. Figure 1 As shown, the upper interface of the connector connects to the gas pipeline, and the left side connects to the quartz tube. All three interfaces of the connector are bolted and threaded. The connector should be made of insulating material; in a preferred embodiment of the invention, the connector is made of polytetrafluoroethylene (PTFE). Good airtightness of the connector is achieved through the fit between the ferrule and the bolt.

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

[0056] The metal electrodes in this device can be made of common metals, including but not limited to 304 stainless steel and tungsten carbide. It is important to note that the metal electrodes should have smooth and flat surfaces to ensure uniform and stable DBD discharge and extend their service life.

[0057] In this device, metal electrodes and a stainless steel tube are connected, and the power supply providing voltage for discharge is not limited to a fixed type. In a preferred embodiment of the invention, a high-frequency AC power supply is used, with a voltage of 7kV or higher and a frequency of 30kHz or higher.

[0058] The following describes the practical effects of a specific embodiment of the present invention:

[0059] In the above specific implementation method, the input gas is air. When the gas flow rate is 1L / min, the plasma activation gas directly acts on the soil in the pipe or diffuses out of the pipe through the small hole to achieve in-situ soil nitrogen fixation. Figure 3 The figure shows the statistical variation of nitrate nitrogen increase with soil depth under different soil moisture conditions. The variation of nitrate nitrogen increase with soil depth exhibits a volcanic curve pattern. Overall, nitrogen fixation is most effective at 13% soil moisture, with the highest increase in nitrate nitrogen at a depth of 4 cm, approximately 427 μg. N ·g -1 soil The increase in nitrate nitrogen decreases as the soil depth and shallower.

[0060] In one embodiment, the air gap between the quartz tube and the stainless steel tube is 1 mm. The stainless steel tube is 2 mm thick, and the radius of the metal electrode is 3.5 mm. The quartz tube is 0.5 mm thick.

[0061] In one embodiment, to ensure uniform soil treatment, partial discharge should be avoided, and a power supply with a power of at least 30W should be selected.

[0062] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0063] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An insertable low temperature plasma array soil nitrogen fixation device, characterized in that, It comprises, a plurality of low-temperature plasma reactors which are arrayed and inserted into the soil, the low-temperature plasma reactors comprising, a stainless steel tube with a plurality of through-holes distributed on the surface, the stainless steel tube being inserted into the soil as a grounding electrode, a connecting fixture with a lower end fixed to the stainless steel tube and a side edge provided with an air pipe, a metal electrode placed in the stainless steel tube as a high-voltage electrode and fixed via the connecting fixture, a quartz tube placed in the stainless steel tube and sleeved on the outer surface of the metal electrode as a barrier medium, a power source connected to the metal electrode and the stainless steel tube, an air source connected to the air pipe, the metal electrode being a finely ground solid round bar with uniform thickness, the stainless steel tube having a thickness of 2 mm, the metal electrode having a radius of 3.5 mm, the outer shell being a grounded stainless steel tube instead of a quartz tube, the single-layer medium reducing the starting discharge voltage and power, and the metal electrode structure realizing uniform dielectric barrier discharge.

2. The plug-in low temperature plasma array soil nitrogen fixation device of claim 1, wherein, The through-holes vertically pass through the tube wall.

3. The plug-in low temperature plasma array soil nitrogen fixation device of claim 1, wherein, The aperture of the through-holes is 1 mm.

4. The insertable low temperature plasma array soil nitrogen fixation device of claim 1, wherein, The connecting fixture is a T-shaped variable-diameter tee joint.

5. The plug-in low temperature plasma array soil nitrogen fixation apparatus of claim 4, wherein, The connecting fixture is made of polytetrafluoroethylene material.

6. The plug-in low temperature plasma array soil nitrogen fixation apparatus of claim 1, wherein, The metal electrode is connected to the positive pole of the power source by wire winding and metal clamps, and the stainless steel tube is connected to the negative pole of the power source by wire winding and metal clamps.

7. The insertable low temperature plasma array soil nitrogen fixation device of claim 1, wherein, The inner diameter of the quartz tube is adapted to the outer diameter of the metal electrode to fix the quartz tube.

8. The insertable low temperature plasma array soil nitrogen fixation device of claim 1, wherein, The power source is an alternating power source.

9. The plug-in low temperature plasma array soil nitrogen fixation apparatus of claim 1, wherein, The discharge voltage is at least 7 kV, and the discharge frequency is at least 30 kHz.

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