A gas phase extraction device for removing and recovering residual fumigant in soil

Abstract

The invention discloses a gas phase extraction device for removing and recovering residual fumigant in soil, belongs to the technical field of soil fumigant recovery, comprises an extraction device which can be inserted into soil, comprises an extraction tube, the upper end of the extraction tube is connected with a vacuum pump and an activated carbon adsorption device in sequence, a portion of the extraction tube inserted into the soil is provided with a plurality of suction holes, the suction holes are arranged along the circumference of the extraction tube, an outer sleeve is provided on the outside of the extraction tube, a plurality of air inlet holes are provided on the circumferential side wall of the outer sleeve, a cavity between the outer sleeve and the extraction tube is filled with particles, air flow channels are provided between adjacent particles, the air flow channels are respectively connected with the suction holes and the air inlet holes, a sedimentation chamber is provided between the bottom wall of the extraction tube and the bottom wall of the outer sleeve, the sedimentation chamber is connected with the air flow channel, the flow path of the air flow in the cavity between the outer sleeve and the extraction tube is extended, the flow resistance of the soil entrained in the air flow is increased, and the probability of blockage of the air flow holes is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of soil fumigant recovery, in particular to a gas phase extraction device for removing and recovering residual fumigant in soil. Background Art

[0002] Soil fumigation is currently the most direct and effective way to prevent and control soil-borne diseases. It can significantly increase crop yields, improve the quality of agricultural products, and help farmers increase their yields and income. In agricultural production, plastic film is immediately covered on the soil surface after the fumigant is applied to prevent the fumigant gas from escaping into the atmosphere. This avoids the escape of fumigant gas, which reduces the prevention effect, and the environmental pollution caused by emissions. However, after the soil fumigation is completed, the traditional method is to remove the plastic film and open the soil to air so that the concentration of residual fumigants in the soil is reduced to a level safe for newly planted crops (this process is called the "waiting period"). During the waiting period, the residual fumigants in the soil will quickly desorb and be discharged into the air, posing a serious threat to human health, especially when accidentally inhaled by fumigant applicators, farmers, farm workers, and bystanders. In addition, the airing process requires a long cycle, generally two to three weeks, or even more than a month, which greatly reduces the utilization rate of the facility land and affects farmers' income.

[0003] The invention patent with application number 201110360143.X fumigates soil samples in a container. This fumigation method is only suitable for laboratories and is not suitable for fumigating land in the field. Moreover, the fumigant gas is directly discharged into the atmosphere after the fumigation, which will cause atmospheric pollution; the invention patent with application number 202010646936.7 is equipped with a chloroform absorption mechanism. After the fumigation is completed, the chloroform absorption mechanism is used to absorb the residual chloroform. Although this device can recover the fumigant after the fumigation is completed, this device is still only suitable for laboratories and cannot be used for land in the field.

[0004] The invention patent with application number 200810000036.4 is equipped with a soil air extractor, the upper end of which is connected to an air pump and an activated carbon adsorber, and the lower end of the soil air extractor is inserted into the soil. This device can extract gas from the soil, but in the process of extracting gas, soil particles will also enter the soil air extractor along with the gas, causing the soil air extractor to be blocked and affecting the extraction efficiency.

[0005] Therefore, the present invention provides a fumigant recovery device that can be applied to field land, which can effectively reduce the probability of blockage of the extraction device when extracting gas from the soil. Summary of the Invention

[0006] The purpose of the present invention is to address the defects and shortcomings of the prior art and provide a gas phase extraction device for removing and recovering residual fumigants in soil. By extending the flow path of the airflow in the cavity between the outer sleeve and the extraction tube, the flow resistance of the soil entrained in the airflow is increased, the flow velocity of the soil is reduced, and the sedimentation effect of the soil is improved, thereby reducing the soil content passing through the extraction holes and reducing the probability of the extraction holes being blocked.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] The present invention provides a gas phase extraction device for removing and recovering residual fumigant in soil, comprising an extraction device that can be inserted into the soil, the extraction device comprising an extraction tube, the upper end of the extraction tube being connected to a vacuum pump and an activated carbon adsorption device in sequence, a portion of the extraction tube inserted into the soil being provided with a plurality of air extraction holes, the air extraction holes being arranged along the circumference of the extraction tube, an outer sleeve being provided on the outside of the extraction tube, a plurality of air inlet holes being provided on the circumferential side wall of the outer sleeve, a cavity between the outer sleeve and the extraction tube being filled with particulate matter for blocking the passage of soil particles, an air flow channel being provided between adjacent particulate matter, the air flow channel being respectively connected to the air extraction holes and the air inlet holes, a sedimentation chamber being provided between the bottom wall of the extraction tube and the bottom wall of the outer sleeve, the sedimentation chamber being connected to the air flow channel;

[0009] Preferably, from top to bottom, the density of the air extraction holes gradually decreases, and the density of the air inlet holes gradually increases;

[0010] Preferably, an annular guide plate is provided between the outer sleeve and the particulate matter located at the lower end, the guide plate comprising an upper plate for guiding the airflow to flow obliquely upward and a lower plate for guiding the airflow to flow obliquely downward, and from bottom to top, the distance between the upper plate and the outer sleeve gradually increases, and the distance between the lower plate and the outer sleeve gradually decreases, an airflow gap is provided between the lower plate and the bottom wall of the outer sleeve, and the airflow gap is connected to the airflow channel;

[0011] Preferably, the upper plate and the lower plate are both straight plates;

[0012] Preferably, a protective net is further provided between the inner wall of the outer sleeve and the particles, the size of the protective net being adapted to the filling space of the particles, and the mesh of the protective net being smaller than the size of the particles;

[0013] Preferably, the upper plate and the lower plate are both fixedly arranged on the protective net;

[0014] Preferably, a plurality of sand shields are provided on the outer wall of the outer sleeve, the sand shields are located above the air inlet, and the sand shields are arranged obliquely downward;

[0015] Preferably, the particulate matter is quartz sand;

[0016] Preferably, the outer sleeve is detachably arranged on the outside of the extraction tube;

[0017] Preferably, the protective net is woven from a plurality of iron wires.

[0018] Compared with the prior art, the present invention has achieved the following technical effects:

[0019] 1. The present invention solves the problem of soil blocking the extraction holes when the extraction tube is inserted into the soil by providing an outer sleeve outside the extraction tube. Filling the space between the extraction tube and the outer sleeve with granules increases the flow resistance of the soil entrained in the air flow, reduces the flow velocity of the soil, and improves the soil settling effect, thereby reducing the amount of soil passing through the extraction holes and reducing the probability of the extraction holes being blocked.

[0020] 2. The present invention arranges the density of the air extraction holes to gradually decrease from top to bottom, while the density of the air inlet holes to gradually increase. A guide plate is provided near the lower air extraction holes to guide the air flow mainly from the lower part of the outer sleeve into the chamber between the outer sleeve and the extraction tube, and mainly from the upper part of the extraction tube into the interior of the extraction tube. This extends the flow path of the air flow, further increases the flow resistance of the soil entrained in the air flow, and reduces the probability of blockage of the air extraction holes.

[0021] 3. The present invention provides a sand barrier on the outside of the outer sleeve. The sand barrier is arranged at an angle downward on the upper part of the air inlet. The sand barrier blocks the air flow into the channel, thereby reducing the area of ​​the channel, reducing the soil content entering the inner part of the outer sleeve with the air flow, and further reducing the probability of blockage of the air extraction hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of the overall structure of the gas phase extraction device;

[0024] Figure 2 Schematic diagram of the structure of the extraction pipe without guide plates and sand retaining plates;

[0025] Figure 3 Schematic diagram of the structure of the extraction pipe with guide plates and sand retaining plates.

[0026] Among them, 1. extraction tube; 2. vacuum pump; 3. activated carbon adsorption device; 4. exhaust hole; 5. outer sleeve; 6. air inlet; 7. particulate matter; 8. sedimentation chamber; 9. guide plate; 10. upper plate; 11. lower plate; 12. protective net; 13. sand retaining plate. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figures 1 to 3 As shown, the present invention provides a gas phase extraction device for removing and recovering residual fumigants in soil, including an extraction device that can be inserted into the soil, the extraction device including an extraction tube 1, the upper end of the extraction tube 1 is connected to a vacuum pump 2 and an activated carbon adsorption device 3 in sequence, the portion of the extraction tube 1 inserted into the soil is provided with a plurality of extraction holes 4, the extraction holes 4 are arranged along the circumference of the extraction tube 1, the outside of the extraction tube 1 is detachably connected to an outer sleeve 5, the circumferential side wall of the outer sleeve 5 is provided with a plurality of air inlet holes 6, the cavity between the outer sleeve 5 and the extraction tube 1 is filled with particles 7 for blocking the passage of soil particles, and air flow is provided between adjacent particles 7. Channel, the air flow channel is connected to the air extraction hole 4 and the air inlet hole 6 respectively, a sedimentation chamber 8 is provided between the bottom wall of the extraction tube 1 and the bottom wall of the outer sleeve 5, and the sedimentation chamber 8 is connected to the air flow channel; generally, after soil fumigation, the soil contains fumigant residue, the saturated vapor pressure of the fumigant is high, and the fumigant is a volatile organic compound. At this time, it is not easy to directly open the film covering the soil surface to discharge the fumigant directly into the air, so the present invention designs such a gas phase extraction device. After the soil fumigation is completed, the extraction tube 1 connected to the vacuum pump 2 and the activated carbon adsorption device 3 is inserted into the soil, the vacuum pump 2 is turned on to start exhausting, and the air flow in the soil is discharged according to the flow rate. Figure 1The fumigant in the soil flows in the direction indicated by the arrow in the middle. After volatilization and desorption, the fumigant in the soil flows out of the soil with the air flow and enters the interior of the activated carbon adsorption device 3, where it is adsorbed in the activated carbon. This solves the problem of directly discharging the fumigant gas into the air and causing atmospheric pollution. An outer sleeve 5 is provided on the outside of the extraction tube 1 to prevent the soil from clogging the extraction hole 4 when the extraction tube 1 is inserted into the soil. Particles 7 are filled between the extraction tube 1 and the outer sleeve 5. When the gas flows through the particles 7, the soil entrained in the air flow will be affected by the particles 7. The obstruction reduces the flow rate, so that the particles sink into the sedimentation chamber 8 under the action of gravity. This method can reduce the soil content passing through the suction hole 4, reduce the probability of blockage of the suction hole 4, and improve the utilization efficiency of the gas phase extraction device. As a specific embodiment of the present invention, the particulate matter 7 is quartz sand; the extraction tube 1 and the outer sleeve 5 are threadedly connected. After the extraction is completed, the outer sleeve 5 is removed from the extraction tube 1, and the particulate matter 7 filled between the extraction tube 1 and the outer sleeve 5 can be replaced or cleaned, and the soil in the sedimentation chamber 8 is taken out.

[0030] In order to reduce the amount of soil entering the outer sleeve 5, the present invention optimizes the arrangement of the air extraction holes 4 and the air inlet holes 6. Specifically, from top to bottom, the density of the air extraction holes 4 gradually decreases, and the density of the air inlet holes 6 gradually increases. This arrangement allows the airflow to mainly enter the cavity between the outer sleeve 5 and the extraction tube 1 from the lower part of the outer sleeve 5, and mainly enter the interior of the extraction tube 1 from the upper part of the extraction tube 1, extending the path of the airflow in the cavity between the extraction tube 1 and the outer sleeve 5, increasing the resistance to the soil during the flow process, reducing the soil content passing through the air extraction holes 4, reducing the probability of blockage of the air extraction holes 4, and improving the utilization efficiency of the gas phase extraction device.

[0031] As a further improvement of the present invention, an annular guide plate 9 is provided between the outer sleeve 5 and the particulate matter 7 located at the bottom. The guide plate 9 includes an upper plate 10 for guiding the airflow to flow obliquely upward and a lower plate 11 for guiding the airflow to flow obliquely downward. From bottom to top, the distance between the upper plate 10 and the outer sleeve 5 gradually increases, and the distance between the lower plate 11 and the outer sleeve 5 gradually decreases. By providing the upper plate 10, the airflow entering the chamber between the outer sleeve 5 and the extraction tube 1 through the air inlet 6 is guided to flow upward and eventually pass through the upper air extraction hole 4 instead of directly passing through the air extraction hole 4 opposite to the air inlet 6; an airflow gap is provided between the bottom of the lower plate 11 and the bottom wall of the outer sleeve 5, and the airflow gap is connected to the airflow channel. The lower plate 11 blocks the air extraction hole 4 at the bottom, so that no air flows along the upper plate 11. The upward-flowing airflow 10 flows downward along the inclined direction of the lower plate 11, and after bypassing the bottom end of the lower plate 11, it flows from bottom to top. Since there are fewer air extraction holes 4 near the bottom, the airflow flowing into the interior of the extraction tube 1 through the air extraction holes 4 here is less, and most of the airflow needs to continue to flow upward and flow into the interior of the extraction tube 1 from the upper air extraction holes 4. This arrangement can further extend the flow path of the airflow and enhance the soil sedimentation effect during the flow process; the upper surfaces of the upper plate 10 and the lower plate 11 can be flat or curved. As a preferred embodiment of the present invention, the upper surfaces of the upper plate 10 and the lower plate 11 are both flat to reduce the difficulty of processing; the upper plate 10 and the lower plate 11 can be formed independently first, and then the connecting parts are welded together, or they can be formed as a whole by stamping.

[0032] A protective net 12 is further provided between the inner wall of the outer sleeve 5 and the particulate matter 7. The size of the protective net 12 is adapted to the filling space of the particulate matter 7. The mesh of the protective net 12 is smaller than the size of the particulate matter 7, that is, the overall size of the protective net 12 is not less than the contact area between the particulate matter 7 and the outer sleeve 5. The provision of the protective net 12 can prevent the particulate matter 7 from overflowing from the air inlet 6. At the same time, in order to prevent the particulate matter 7 from passing through the air extraction hole 4 and entering the extraction tube 1, the maximum aperture of the air extraction hole 4 is set to be smaller than the minimum particle size of the particulate matter 7. As a specific embodiment of the present invention, The protective net 12 is woven from a plurality of iron wires, and the upper plate 10 and the lower plate 11 are fixedly mounted on the protective net 12. Specifically, the upper plate 10 and the lower plate 11 can be welded to the protective net 12, or arc-shaped flanges can be provided at the ends of the upper plate 10 and the lower plate 11, through which the upper plate 10 and the lower plate 11 are hung on the protective net 12, respectively. Through holes can also be provided at the ends of the upper plate 10 and the lower plate 11, through which thin iron wire, steel wire rope, or other indestructible rope-like structures are passed and tied to the protective net 12. The upper plate 10 and the lower plate 11 are preferably made of a metal material with high structural strength.

[0033] As a further improvement of the present invention, a plurality of sand guards 13 are provided on the outer wall of the outer sleeve 5. The plurality of sand guards 13 are located at the upper part of the air inlet 6, and the sand guards 13 are arranged tilted downward. By arranging the sand guards 13, the soil content entering the inner part of the outer sleeve 5 through the air inlet 6 can be further reduced. The sand guards 13 are also preferably made of metal material with higher structural strength. In order to improve the connection firmness between the sand guards 13 and the outer sleeve 5, the present invention welds the sand guards 13 to the outer wall of the outer sleeve 5.

[0034] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all perspectives, the embodiments should be regarded as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description. It is intended that all changes that fall within the meaning and range of equivalents of the claims be included in the present invention, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

Claims

1. A gas phase extraction device for removing and recovering residual fumigant in soil, characterized in that: The invention comprises an extraction device which can be inserted into the soil, the extraction device comprises an extraction tube, the upper end of the extraction tube is connected to a vacuum pump and an activated carbon adsorption device in sequence, a portion of the extraction tube inserted into the soil is provided with a plurality of air extraction holes, the air extraction holes are arranged along the circumference of the extraction tube, an outer sleeve is provided on the outside of the extraction tube, a plurality of air inlet holes are provided on the circumferential side wall of the outer sleeve, a cavity between the outer sleeve and the extraction tube is filled with particles for blocking the passage of soil particles, an air flow channel is provided between adjacent particles, the air flow channel is respectively connected to the air extraction holes and the air inlet holes, a sedimentation chamber is provided between the bottom wall of the extraction tube and the bottom wall of the outer sleeve, the sedimentation chamber is connected to the air flow channel; From top to bottom, the density of the air extraction holes gradually decreases, and the density of the air inlet holes gradually increases.

2. The gas phase extraction device according to claim 1, characterized in that: An annular guide plate is provided between the outer sleeve and the particles located at the lower end, and the guide plate includes an upper plate for guiding the airflow to flow obliquely upward and a lower plate for guiding the airflow to flow obliquely downward. From bottom to top, the distance between the upper plate and the outer sleeve gradually increases, and the distance between the lower plate and the outer sleeve gradually decreases. An airflow gap is provided between the lower plate and the bottom wall of the outer sleeve, and the airflow gap is connected to the airflow channel.

3. The gas phase extraction device according to claim 2, characterized in that: The upper plate and the lower plate are both straight plates.

4. The gas phase extraction device according to claim 3, characterized in that: A protective net is also provided between the inner wall of the outer sleeve and the particles. The size of the protective net is adapted to the filling space of the particles, and the mesh of the protective net is smaller than the size of the particles.

5. The gas phase extraction device according to claim 4, characterized in that: The upper plate and the lower plate are both fixedly arranged on the protective net.

6. The gas phase extraction device according to claim 5, characterized in that: A plurality of sand baffles are arranged on the outer wall of the outer sleeve, the sand baffles are located at the upper part of the air inlet, and the sand baffles are arranged to be inclined downward.

7. The gas phase extraction device according to claim 1, characterized in that: The particulate matter is quartz sand.

8. The gas phase extraction device according to claim 1, characterized in that: The outer sleeve is detachably arranged outside the extraction tube.

9. The gas phase extraction device according to claim 4, characterized in that: The protective net is woven from a plurality of iron wires.

Images