Seed density selecting and grading equipment and method

Abstract

The invention provides a seed density selecting and grading device and method.The device comprises a liquid quantitative preparation module, a density separation module, a liquid recycling module and a liquid suction filtration module, and the liquid quantitative preparation module is used for preparing liquid with the preset density and conveying the liquid to the density separation module; the density separation module is provided with a bin body for separating seeds with different densities, the density separation module conveys the separated seeds to the liquid recycling module, the liquid recycling module separates the seeds from liquid, and the separated liquid is conveyed to the liquid suction filtration module; and the liquid suction filtration module is used for filtering the liquid to realize recycling. The device is highly automatic, rapid seed-liquid separation, rapid seed drying and high-efficiency liquid recovery are realized, manual intervention is reduced, the working efficiency and accuracy are improved, and the labor intensity and the cost are reduced. By utilizing the buoyancy characteristic of liquid, the same batch of seeds can be accurately divided into a plurality of layers according to the density, and the germination uniformity of the seeds is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of seed selection and grading equipment, and in particular to a seed density selection and grading equipment and method. Background Art

[0002] Seed selection and grading is an important means to improve seed quality and is crucial to ensure the healthy growth and high yield of crops. In the tobacco planting industry, the quality of seeds is directly related to the quality and yield of tobacco leaves, so it is particularly important to accurately and efficiently sort tobacco seeds. At present, the selection of tobacco seeds mainly relies on two traditional methods: wind selection and screening.

[0003] However, these methods have obvious shortcomings: the sorting accuracy is poor, and it is difficult to achieve high-precision seed grading; it is easy to cause mechanical damage to the seeds, affecting their germination ability and later growth performance; especially for aging and deteriorating inventory seeds whose quality cannot be improved after repeated air separation and screening, seeds that cannot be stored due to physiological maturity, and rare and precious flowers and medicinal seeds, the effect of traditional methods is very limited.

[0004] How to achieve high-precision grading of tobacco seeds has become a difficult problem that restricts the development of tobacco seed processing technology. This issue is not only related to the further improvement of tobacco seed quality, but also involves the enhancement of precision processing capabilities, thereby promoting the high-quality development of the entire tobacco seed industry. At present, the industry lacks systematic, appropriate and widely popularizable density sorting technology and supporting equipment.

[0005] At present, the limitations of the above traditional methods can be effectively overcome through liquid density sorting technology. Static density sorting uses the buoyancy characteristics of liquid to naturally stratify seeds immersed in liquid according to their density - low-density seeds float on the upper part of the liquid, medium-density seeds are suspended in the middle, and high-density seeds sink to the bottom. This method can achieve highly fine grading of the same batch of seeds. However, although liquid density sorting technology has shown significant advantages, it is still in the laboratory stage and has not been put into actual production. There is no systematic, suitable, and popularizable density sorting technology and supporting sorting devices. To this end, a seed density selection and grading device and method are proposed to solve the above problems. Summary of the invention

[0006] In view of this, the present invention provides a seed density selection and grading device and method, aiming to solve the problem that the existing liquid density sorting technology in the background technology cannot achieve systematic and mass production.

[0007] The present invention provides a seed density selection and grading device, comprising a liquid quantitative preparation module, a density separation module, a liquid circulation recovery module and a liquid filtration module. The liquid quantitative preparation module is used to prepare liquid of preset density and transport it to the density separation module, the density separation module is provided with a bin for separating seeds of different densities, the density separation module transports the separated seeds to the liquid circulation recovery module, the liquid circulation recovery module separates the seeds from the liquid, and the separated liquid is transported to the liquid filtration module, the liquid filtration module filters the liquid to achieve the recycling of the liquid.

[0008] On the basis of the above scheme, it also includes a liquid storage module. The liquid filtration module stores the filtered liquid in the liquid storage module, and the liquid quantitative preparation module can also store the prepared liquid in the liquid storage module.

[0009] To further describe the above scheme, the liquid quantitative preparation module includes a mixing module, a metering pump, a n-hexane storage tank and a dichloromethane storage tank. The n-hexane storage tank and the dichloromethane storage tank are sealed to store n-hexane and dichloromethane respectively. Two metering pumps are provided, and n-hexane and dichloromethane are quantitatively pumped into the mixing module respectively. The mixing module includes a mixing motor, a mixing tank, and a paddle. The mixing motor drives the paddle to stir and mix the n-hexane and dichloromethane in the mixing tank.

[0010] Furthermore, a liquid inlet pump and a liquid storage tank are arranged between the liquid quantitative preparation module and the density separation module. The liquid inlet pump draws the liquid in the mixing tank into the liquid storage tank. A valve is arranged at the bottom of the liquid storage tank and is connected to the pipeline of the density separation module to quantitatively transport the prepared liquid to the density separation module.

[0011] Further describing the above scheme, the density separation module includes a lower bin, a valve, and an upper bin. The valve is located between the lower bin and the upper bin to separate seeds of different densities. The lower bin is connected to the liquid circulation recovery module through a pipeline. Optionally, the valve between the lower bin and the upper bin adopts a three-way valve, which can discharge the seed liquid in the lower bin and the upper bin to the liquid circulation recovery module at the same time.

[0012] Furthermore, the lower bin of the density separation module is a double-conical container, and the upper bin is a conical container. An electric through valve is arranged between the lower bin and the upper bin. The lower bin and the upper bin also include a nozzle and a vibrator. The nozzle is connected to the liquid storage tank to spray the seeds attached to the inner wall of the bin to make them fall to the bottom of the container; the vibrator vibrates the liquid and seeds to promote the rapid stratification of seeds of different densities.

[0013] Further description of the aforementioned scheme, the liquid circulation recovery module includes a sealed tank, two collecting trays are arranged on both sides of the sealed tank, and a conical liquid collecting bucket is provided below the collecting tray, and the liquid collecting bucket is connected to the liquid filtration module; two feed pipes are arranged above the collecting tray, and the feed pipes are connected to the density separation module through a three-way valve, and the three-way valve distributes seeds of different densities to different collecting trays. The collecting tray drawer-type seals are installed on both sides of the sealed tank, and the collecting tray is provided with filter holes for separating seeds and liquids.

[0014] Optionally, the sealed tank is also connected to a drying system, the air inlet of the drying system is located above the collecting tray, and the air outlet is located on the side of the sealed tank, and the drying system dries the seeds on the collecting tray.

[0015] Further description of the above-mentioned scheme, the liquid filtration module includes a filter, and the filter is provided with at least a first filter cartridge and a second filter cartridge, filter cotton is arranged inside the first filter cartridge and the second filter cartridge, and three-way valves are arranged at both ends of the first filter cartridge and the second filter cartridge, the three-way valve at the liquid inlet end of the filter cartridge is connected to the liquid circulation recovery module, and the three-way valve at the liquid outlet end of the filter cartridge is connected to the liquid inlet pump.

[0016] The present invention also provides a seed density selection and grading method, comprising the above-mentioned seed density selection and grading device, comprising the following steps:

[0017] S1: The liquid quantitative preparation module pumps the n-hexane and dichloromethane stored in the liquid storage tank into the mixing tank of the mixing module, and the paddles inside the mixing tank stir and mix the liquids;

[0018] S2: The mixed liquid is pumped into a liquid storage tank for standby use;

[0019] S3: The seed tank puts a certain amount of seeds into the density separation module, and the liquid storage tank transports a certain amount of liquid to the density separation module;

[0020] S4: The vibrator vibrates the liquid and seeds in the density separation module, so that the seeds with different densities are quickly layered into the lower bin and the upper bin, and the straight-through valve closes the passage between the lower bin and the upper bin;

[0021] S5: The three-way valve at the bottom of the lower bin is switched to the side of the high-density seed collection plate, and the liquid and seeds in the lower bin are discharged to the high-density seed collection plate of the liquid circulation recovery module, and the nozzle sprays the wall of the lower bin to blow off the seeds attached to the inner wall of the bin; the three-way valve is switched to the side of the low-density seed collection plate, and the straight-through valve is opened to discharge the liquid and seeds in the upper bin to the low-density seed collection plate of the liquid circulation recovery module;

[0022] S6: The liquid in the liquid circulation recovery module enters the filter and passes through the liquid inlet pump, which pumps the filtered liquid to the liquid storage tank;

[0023] S7: The drying device dries the seeds in the collecting tray.

[0024] The seed density selection and grading device and method provided by the present invention have significant advantages and wide applicability:

[0025] High-precision grading: By utilizing the buoyancy characteristics of liquid, the same batch of seeds can be accurately divided into multiple layers according to density, significantly improving the uniformity of seed germination, which is especially important for crops such as tobacco seeds that require a high germination rate.

[0026] Reduce mechanical damage: Avoid physical damage to seeds that may be caused by traditional winnowing and screening processes, protect the integrity and germination ability of seeds, and are especially suitable for fragile seeds such as rare and precious flowers and medicinal seeds.

[0027] Environmental protection and economy: It realizes efficient recycling of sorting liquid, reduces resource consumption and environmental pollution, reduces the use of chemicals, and conforms to the development trend of green agriculture.

[0028] Wide scope of application: It is not only suitable for tobacco seeds, but can also be extended to other types of small-grain seeds, such as vegetables, grains, oil crops, etc. It has strong adaptability and broad application prospects.

[0029] High degree of automation: The entire process is highly automated, reducing manual intervention, improving work efficiency and accuracy, and reducing labor intensity and costs.

[0030] Easy and safe operation: Reasonable design of operating procedures and safety protection measures ensures the safety of operators and long-term stable operation of equipment, which is particularly suitable for large-scale industrial production.

[0031] Data traceability: Combined with modern information technology, the data of each sorting can be recorded and a detailed report can be generated to facilitate subsequent quality traceability and management, which helps to establish a complete seed quality management system.

[0032] In summary, the present invention provides a systematic, suitable and popularizable seed density selection and grading technology and supporting equipment, which provides an effective solution to the bottleneck problem in the current tobacco seed processing field and promotes the development of the tobacco seed industry and related fields to a higher level. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of 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 creative work.

[0034] Figure 1 A principle block diagram provided for an embodiment of the present invention;

[0035] Figure 2 , 3 An overall schematic diagram provided for an embodiment of the present invention;

[0036] Figure 4 A schematic diagram of a local structure provided by an embodiment of the present invention;

[0037] Figure 5 A schematic diagram of a filter and a liquid circulation recovery module provided in an embodiment of the present invention;

[0038] Figure 6 A schematic diagram of the structure of a density separation module provided in an embodiment of the present invention;

[0039] Figure 7 A cross-sectional view of a density separation module provided by an embodiment of the present invention;

[0040] Figure 8 A cross-sectional view of a liquid circulation recovery module provided in an embodiment of the present invention.

[0041] Among them, the reference numerals in the figure are:

[0042] 1. Density separation module; 11. Lower bin; 12. Straight-through valve; 13. Upper bin; 14. Nozzle; 15. Vibrator; 2. Liquid circulation recovery module; 21. Collection tray; 22. Three-way valve; 23. Feed pipe; 24. Liquid collecting bucket; 25. Discharge pipe; 3. Filter; 31. First filter cartridge; 32. Second filter cartridge; 33. Solenoid valve; 34. Recovery pipe; 4. Liquid inlet pump; 5. Liquid storage tank; 6. Seed tank; 7. Mixing module; 71. Mixing motor; 72. Mixing tank; 8. Metering pump; 9. Recovery barrel; 91. Hexane liquid storage tank; 92. Dichloromethane liquid storage tank.

[0043] The above drawings have shown clear embodiments of the present invention, which will be described in more detail below. These drawings and text descriptions are not intended to limit the scope of the present invention in any way, but to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0045] To make the technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0046] See also Figures 1 to 8 As shown, the present invention provides a seed density selection and grading device, which includes the following main modules: a liquid quantitative preparation module, a density separation module 1, a liquid circulation recovery module 2, a liquid filtration module, and a liquid storage module. Among them:

[0047] Liquid quantitative preparation module: used to configure liquid of preset density and transport it to density separation module 1. This module includes mixing module 7, metering pump 8, n-hexane storage tank 91 and dichloromethane storage tank 92. n-hexane and dichloromethane are sealed and stored in their respective storage tanks 5, and two independent metering pumps 8 quantitatively extract these two solvents into mixing module 7. Mixing module 7 is equipped with mixing motor 71, mixing tank 72 and paddles. Mixing motor 71 drives paddles to evenly stir the liquid in mixing tank 72. n-hexane and dichloromethane storage tanks 92 are made of stainless steel or high-density polyethylene HDPE. These materials can resist the erosion of solvents and ensure long-term stable use. All joints and joints of storage tank 5 must have good sealing performance to prevent liquid leakage or volatilization. Teflon lining or other forms of high-efficiency sealing devices can be used. Ventilation system: Appropriate exhaust holes or breathing valves should be installed on the top of storage tank 5 to adjust the internal pressure, and a gas detector should be equipped to monitor the gas concentration in the tank in real time to ensure safety. It should be noted that other inorganic and organic solvent liquid separation media of different densities can be selected. In this embodiment, only n-hexane and dichloromethane are used. The metering pump 8 is a diaphragm metering pump 8. The diaphragm metering pump 8 has the properties of high precision, safety, reliability, corrosion resistance, etc. The diaphragm design prevents the risk of chemical leakage, protects the safety of operators, can resist the erosion of n-hexane and dichloromethane, and prolongs the service life.

[0048] Density separation module 1: It is equipped with a special chamber to separate seeds of different densities. Figure 6 , 7As shown, the module includes a lower bin 11, a through valve 12, and an upper bin 13. The lower bin 11 is a double-conical container, and the upper bin 13 is a conical container. An electric through valve 12 is arranged between the lower bin 11 and the upper bin 13 to separate seeds of different densities. The lower bin 11 and the upper bin 13 are also equipped with a nozzle 14 and a vibrator 15. The nozzle 14 is connected to the liquid storage tank 5 to spray and remove the seeds attached to the inner wall of the bin; the vibrator 15 promotes the rapid stratification of the liquid and seeds. The vibrator 15 is usually a motor or an electromagnetic drive device as a vibration source. When the current passes through the coil, reciprocating motion or rotational motion is generated under the action of the magnetic field, which is then converted into vibration output. In order to effectively transmit the vibration to the seeds and liquid in the bin body, the vibrator 15 may be directly installed on the bin body wall, or indirectly connected through an elastic connector. This ensures that the vibration energy is evenly distributed in the entire separation space to avoid local over-vibration or under-vibration. In some embodiments, an ultrasonic vibrator 15 can also be used. The ultrasonic vibrator 15 converts electrical energy into high-frequency mechanical vibrations through a transducer, and the frequency is usually more than 20kHz. This vibration propagates into the liquid at an extremely high frequency, generating a small but efficient disturbance. When the ultrasonic wave propagates in the liquid, it forms tiny bubbles in the local area, i.e., cavitation. These bubbles expand and collapse rapidly, generating strong local shock waves and microjets, which help to destroy the surface tension of the liquid, accelerate the relative movement between seeds, and promote the rapid separation of seeds of different densities. It should be noted that in this embodiment, only the upper warehouse 13 and the lower warehouse 11 are provided. In other embodiments, more warehouses can be provided as needed to separate seeds of various densities. It should be noted that in other embodiments, a three-way valve can be provided between the lower warehouse 11 and the upper warehouse 13, so that the seeds and liquid in the upper warehouse 13 flow directly to the liquid circulation recovery module 2 through the three-way valve. At the same time, two separate collection tanks can be provided in the liquid circulation recovery module 2 for collecting seeds of different densities.

[0049] Liquid recycling module 2: Figure 5 , 8As shown, the liquid circulation recovery module 2 is responsible for separating the separated seeds from the liquid, and the collection tank collects seeds of different density levels. The module includes a sealed tank, and two drawer-type sealed collection trays 21 are arranged on both sides of the sealed tank, and a conical liquid collecting hopper 24 is arranged below. The bottom of the liquid collecting hopper 24 is connected to the liquid suction filtration module through a drain pipe 25. The feed pipe 23 is connected to the density separation module 1 through a three-way valve 22, and the three-way valve 22 is distributed to different collection trays 21 according to the seed density. The sealed tank is also connected to a drying system, and the air inlet of the drying system is located above the collection tray 21, and the air outlet is located on the side of the sealed tank. The drying system dries the seeds on the collection tray 21, which is not shown in the figure. It should be noted that a sealing ring is arranged between the collection tray 21 and the sealed tank to achieve a sealed installation to prevent leakage of n-hexane and dichloromethane. In other embodiments, the drying system is separately arranged and is not connected to the liquid circulation recovery module 2. When drying is required, the seeds of the collection tray 21 are taken out and placed in the drying system. In other embodiments, the liquid recycling module 2 may adopt a two-layer collection tank, wherein the upper layer has a nylon mesh bag for collecting seeds, and the lower layer liquid flows out of the mesh bag and is pumped into a liquid storage tank for recycling.

[0050] Liquid filtration module: Figure 5 As shown, the separated liquid is filtered to ensure that it can be recycled. The module includes at least two filter cartridges, a first filter cartridge 31 and a second filter cartridge 32, with filter cotton arranged inside and three-way valves 22 arranged at both ends. The three-way valve 22 at the liquid inlet end of the filter cartridge is connected to the liquid circulation recovery module 2, and the three-way valve 22 at the liquid outlet end is connected to the liquid inlet pump 4 through a recovery pipe 34, so as to draw the filtered liquid back to the liquid storage tank 5. The working principle of the filter 3 is as follows: firstly, the three-way valve 22 is set so that the liquid circulation recovery module 2 is connected to the first filter cartridge 31 and the liquid inlet pump 4 in turn. At this time, the second filter cartridge 32 is not connected to the system, and the filter cotton and filter element of the second filter cartridge 32 can be disassembled and cleaned; similarly, the liquid circulation recovery module 2 can be connected to the second filter cartridge 32 and the liquid inlet pump 4 in turn. At this time, the first filter cartridge 31 is not connected to the system, and the filter cotton and filter element of the first filter cartridge 31 can be disassembled and cleaned.

[0051] Liquid storage module: used to store filtered liquid to ensure a stable supply and safe storage of liquid. Liquid quantitative preparation module can also store prepared liquid in this module for subsequent use.

[0052] All modules of the equipment can be installed on a rack with rollers for easy movement, or they can be fixed on the bracket of the factory. It should be noted that during installation, a spacious operating space with ventilation and exhaust for density sorting and related supporting facilities must be established. The overall equipment has good airtightness to ensure that the sorted liquid will not leak.

[0053] In order to have a more thorough and comprehensive understanding of the disclosure of the present invention, the principle thereof is further explained below in conjunction with the usage method.

[0054] For tobacco seeds, according to previous studies, the seeds with a density of 1.00g / ml≤ρ<1.15g / ml have the highest germination potential and germination rate. Therefore, the operation method is to use n-hexane and dichloromethane to prepare a mixed liquid with a density of 1.00g / ml, and the liquid: seed volume ratio is >2:1; vibrate and stir, stand, and stratify the seeds, separate the seeds with a density of <1.00g / ml suspended in the upper and middle parts of the liquid, retain the seeds in the lower part, and pour out all the liquid. Use the above liquid to prepare a mixed liquid with a density of 1.15g / ml, add it to the seeds left in the lower part, the liquid: seed volume ratio is >2:1, stir, stand, and stratify the seeds again, retain the seeds with a density of ≤1.15g / ml suspended in the upper and middle parts, and remove the seeds that sink to the bottom >1.15g / ml, and the sorting can be completed. In the latter step, the seeds with a density of >1.15g / ml generally have very little content, and can be omitted according to actual conditions.

[0055] The specific steps are as follows:

[0056] S1: The liquid quantitative preparation module pumps the n-hexane and dichloromethane stored in the liquid storage tank 5 into the mixing tank 72 of the mixing module 7 by means of a diaphragm metering pump 8, and the paddles inside the mixing tank 72 stir and mix the liquids;

[0057] S2: The mixed liquid is pumped into the liquid storage tank 5 by the liquid inlet pump 4 for standby use. It should be noted that a quantitative liquid dispensing device is provided below the liquid storage tank 5 to deliver a quantitative amount of liquid to the density separation module 1;

[0058] S3: The seed tank 6 puts a certain amount of seeds into the density separation module 1, and the liquid storage tank 5 transports a certain amount of liquid to the density separation module 1;

[0059] S4: The vibrator 15 vibrates the liquid and seeds in the density separation module 1, so that the seeds of different densities are quickly layered into the lower bin 11 and the upper bin 13. After 3-5 minutes, the through valve 12 closes the passage between the lower bin 11 and the upper bin 13. Figure 7 As shown;

[0060] S5: The three-way valve 22 at the bottom of the lower bin 11 is switched to the side of the high-density seed collection tray 21, and the liquid and high-density seeds in the lower bin 11 are discharged to the high-density seed collection tray 21 of the liquid circulation recovery module 2, and the nozzle 14 sprays the wall of the lower bin 11 to blow off the seeds attached to the inner wall of the bin body; then, the three-way valve 22 is switched to the side of the low-density seed collection tray 21, and the through valve 12 is opened to discharge the liquid and seeds in the upper bin 13 to the low-density seed collection tray 21 of the liquid circulation recovery module 2;

[0061] S6: After the liquid in the liquid recycling module 2 enters the filter 3, the filtered liquid is pumped to the liquid storage tank 5 through the liquid inlet pump 4. It should be noted that the liquid inlet pump 4 has two liquid inlet pipes, which are respectively connected to the filter 3 and the mixing tank 72, and valves are installed on the two liquid inlet pipes. The liquid inlet pump 4 can selectively suck the liquid in the liquid recycling module 2 or the liquid in the mixing tank 72;

[0062] S7: The drying device dries the seeds in the collection tray 21. The air inlet of the drying system is located above the collection tray 21 and blows downward, and the air outlet is located on the side of the sealed tank. The drying system dries the seeds on the collection tray 21. It should be noted that the drying system can be set up separately and is not connected to the liquid recycling module 2. When drying is required, the seeds in the collection tray 21 are taken out and placed in the drying system.

[0063] Among them, two pipes are arranged below the liquid storage tank 5 , which are respectively connected to the density separation module 1 and the recovery barrel 9 , and solenoid valves are arranged on the pipes to control the flow direction of the liquid in the liquid storage tank 5 .

[0064] It should be noted that the present device and method can be used to separate not only tobacco seeds, but also flowers, medicinal seeds, etc.

[0065] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the present invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the claims above.

[0066] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A seed density selection and grading device, characterized in that: The invention comprises a liquid quantitative preparation module, a density separation module (1), a liquid circulation recovery module (2) and a liquid filtration module, wherein the liquid quantitative preparation module is used to prepare liquid of a preset density and transport it to the density separation module (1), the density separation module (1) is provided with a bin body for stratifying seeds of different densities, the density separation module (1) transports the separated seeds to the liquid circulation recovery module (2), the liquid circulation recovery module (2) separates the seeds from the liquid, and the separated liquid is transported to the liquid filtration module, and the liquid filtration module filters the liquid.

2. A seed density selection and grading device according to claim 1, characterized in that: It also includes a liquid storage module, and the liquid filtration module stores the filtered liquid in the liquid storage module.

3. The seed density selection and grading device according to claim 1, characterized in that: The liquid quantitative preparation module comprises a mixing module (7), a metering pump (8), a n-hexane storage tank (91) and a dichloromethane storage tank (92); the n-hexane storage tank (91) and the dichloromethane storage tank (92) are sealed to store n-hexane and dichloromethane respectively; two metering pumps (8) are provided to pump n-hexane and dichloromethane quantitatively into the mixing module (7) respectively; the mixing module (7) comprises a mixing motor (71), a mixing tank (72) and a paddle; the mixing motor (71) drives the paddle to stir and mix the n-hexane and dichloromethane in the mixing tank (72).

4. A seed density selection and grading device according to claim 3, characterized in that: A liquid inlet pump (4) and a liquid storage tank (5) are provided between the liquid quantitative preparation module and the density separation module (1); the liquid inlet pump (4) pumps the liquid in the mixing tank (72) into the liquid storage tank (5); a valve is provided at the bottom of the liquid storage tank (5) and is connected to the pipeline of the density separation module (1) to quantitatively transport the prepared liquid to the density separation module (1).

5. The seed density selection and grading device according to claim 1, characterized in that: The density separation module (1) comprises a lower bin (11), a valve, and an upper bin (13); the valve is located between the lower bin (11) and the upper bin (13) to separate seeds of different densities; the lower bin (11) is connected to a liquid circulation recovery module (2) via a pipeline.

6. The seed density selection and grading device according to claim 5, characterized in that: The lower bin (11) of the density separation module (1) is a double-conical container, and the upper bin (13) is a conical container. An electric through valve (12) is provided between the lower bin (11) and the upper bin (13). The lower bin (11) and the upper bin (13) further include a nozzle (14) and a vibrator (15). The nozzle (14) is connected to a liquid storage tank (5) to spray seeds attached to the inner wall of the bin to make them fall to the bottom of the container. The vibrator (15) vibrates the liquid and the seeds to quickly separate the seeds into layers with different densities.

7. The seed density selection and grading device according to claim 1, characterized in that: The liquid circulation recovery module (2) comprises a sealed tank, two collecting trays (21) are arranged on both sides of the sealed tank, a conical liquid collecting hopper (24) is arranged below the collecting tray (21), and the liquid collecting hopper (24) is connected to the liquid filtration module; two feeding pipes (23) are arranged above the collecting tray (21), and the feeding pipes (23) are connected to the density separation module (1) through a three-way valve (22), and the three-way valve (22) distributes seeds of different densities to different collecting trays (21), and the collecting trays (21) are installed on both sides of the sealed tank in a drawer-type sealing manner.

8. The seed density selection and grading device according to claim 7, characterized in that: The sealed tank is also connected to a drying system, the air inlet of the drying system is located above the collecting tray (21), and the air outlet is located on the side of the sealed tank. The drying system dries the seeds on the collecting tray (21).

9. The seed density selection and grading device according to claim 1, characterized in that: The liquid filtration module comprises a filter (3), wherein the filter (3) is provided with at least a first filter cartridge (31) and a second filter cartridge (32), wherein filter cotton is provided inside the first filter cartridge (31) and the second filter cartridge (32), and three-way valves (22) are provided at both ends of the first filter cartridge (31) and the second filter cartridge (32), wherein the three-way valve (22) at the liquid inlet end of the filter cartridge is connected to the liquid circulation recovery module (2), and the three-way valve (22) at the liquid outlet end of the filter cartridge is connected to the liquid inlet pump (4).

10. A seed density selection and grading method, comprising the seed density selection and grading device according to claims 1 to 9, characterized in that: The following steps are included S1: The liquid quantitative preparation module pumps n-hexane and dichloromethane stored in the liquid storage tank (5) into the mixing tank (72) of the mixing module (7) in a quantitative manner, and the paddles inside the mixing tank (72) stir and mix the liquids; S2: The mixed liquid is pumped into a liquid storage tank (5) for standby use; S3: The seed tank (6) puts a certain amount of seeds into the density separation module (1), and the liquid storage tank (5) transports a certain amount of liquid to the density separation module (1); S4: the vibrator (15) vibrates the liquid and seeds in the density separation module (1), so that the seeds of different densities are quickly layered into the lower bin (11) and the upper bin (13), and the through valve (12) closes the passage between the lower bin (11) and the upper bin (13); S5: the three-way valve (22) at the bottom of the lower bin (11) is switched to the side of the high-density seed collection plate (21), and the liquid and seeds in the lower bin (11) are discharged to the high-density seed collection plate (21) of the liquid circulation recovery module (2), and the nozzle (14) sprays the wall of the lower bin (11) to blow off the seeds attached to the inner wall of the bin; the three-way valve (22) is switched to the side of the low-density seed collection plate (21), and the through valve (12) is opened, and the liquid and seeds in the upper bin (13) are discharged to the low-density seed collection plate (21) of the liquid circulation recovery module (2); S6: The liquid in the liquid recycling module (2) enters the filter (3) and passes through the liquid inlet pump (4), and the liquid inlet pump (4) pumps the filtered liquid into the liquid storage tank (5); S7: The drying device dries the seeds in the collecting tray (21).

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