Control system and method for grain fumigation by using phosphorane mixed gas

Abstract

The invention relates to the technical field of phosphine mixed gas control, and particularly discloses a control system and method for grain fumigation through phosphine mixed gas, and the method comprises the following steps: S1, determining the optimal phosphine concentration required by grain in unit volume through experimental data, longitudinally layering a grain pile, and calculating the volume of each layer and the corresponding phosphine concentration requirement; s2, gas distribution points are evenly arranged in the fumigation bin, the proportion of mixed gas is determined according to the bin volume and the layered phosphine concentration requirement, the initial conveying time is calculated in combination with the initial gas outlet rate, and the phosphine mixed gas is conveyed in proportion; s3, monitoring points are arranged at the gas distribution points, the concentration change of phosphorane is monitored in real time, a gas flowing path is analyzed, and gas distribution parameters are dynamically adjusted to ensure the fumigation uniformity and effect; through layered calculation, dynamic monitoring and adjustment, precise control over the phosphine mixed gas is achieved, and the fumigation efficiency and safety are improved.

Description

Technical Field

[0001] This invention relates to the field of phosphine mixed gas control technology, specifically to a control system and method for using phosphine mixed gas for grain fumigation. Background Technology

[0002] In the food storage sector, ensuring food quality and safety is paramount, and pest infestation is one of the key factors affecting food quality. Grains, cereals, nuts, dried goods, and other food products are highly susceptible to pest damage during storage, causing not only economic losses but also potential spoilage and toxin production due to pest infestation, seriously threatening consumer health.

[0003] Traditional food storage fumigation processes often rely on the on-site reaction of metal phosphides (aluminum phosphide, magnesium phosphide, etc.) with water to produce phosphine. Aluminum phosphide itself is somewhat toxic, and its storage and transportation pose even higher safety risks in food storage environments. Leaks or improper handling can directly contaminate food. In practice, the reaction of aluminum phosphide with water to produce phosphine for fumigation generates a large amount of complex solid waste, increasing the cost of solid waste storage and treatment. If this solid waste is not properly treated, residual phosphides may indirectly affect the growth environment of food raw materials through soil and water, thus impacting food safety. Moreover, the reaction rate during on-site phosphine production is greatly affected by environmental factors and is difficult to precisely control, resulting in significant fluctuations in the concentration of the produced phosphine. Excessive concentration can easily lead to explosions and other safety accidents, damaging food storage facilities; insufficient concentration cannot effectively kill pests, failing to guarantee food storage safety.

[0004] Phosphine, as a highly effective fumigant, can rapidly kill various storage pests under ideal conditions. However, its flammable and explosive properties pose a significant obstacle in food storage environments. Food storage facilities typically store large quantities of flammable food ingredients, and the consequences of a phosphine explosion would be unimaginable. To control the risk, the concentration of phosphine must be strictly controlled when used alone. This means that in some food storage scenarios with high pest densities or complex environments, its highly effective insecticidal performance cannot be fully realized.

[0005] Traditional phosphine and CO2 mixing processes have serious drawbacks in the application of mixed gases. Due to a lack of precise mixing control technology, the ratio of the mixed gases is difficult to maintain stably, and stratification easily occurs during storage and transportation. This results in inconsistent gas concentrations in different areas during actual fumigation. In some areas, the phosphine concentration is too high, posing a safety hazard and potentially contaminating food; in other areas, the concentration is too low to effectively kill insects, leading to significant fluctuations in fumigation effectiveness and failing to provide continuous and stable protection for food storage. The mixed gas involved in this invention contains only phosphine and carbon dioxide, solving the above problems through an innovative process.

[0006] In summary, existing food storage fumigation technologies have many problems in terms of safety, environmental protection, cost control, and the stability of fumigation effects. There is an urgent need for an innovative technology to solve these problems. This invention is based on this background and involves in-depth research and development. Summary of the Invention

[0007] The purpose of this invention is to provide a control system and method for using phosphine mixed gas for grain fumigation, thereby solving the above-mentioned technical problems.

[0008] The objective of this invention can be achieved through the following technical solutions: A method for controlling the use of phosphine mixed gas in grain fumigation includes the following steps: Step S1: Obtain experimental data; based on the experimental data, obtain the optimal phosphine concentration required per unit volume of grain; obtain the grain pile in the fumigation chamber, divide the grain pile longitudinally into several layers, and obtain the volume of each layer of the grain pile; based on the volume of the grain pile layer and the optimal phosphine concentration, obtain the required phosphine concentration for each layer of the grain pile. Step S2: Set several air distribution points at equal intervals in the fumigation chamber, obtain the volume of the fumigation chamber, and obtain the mixed gas ratio according to the required phosphine concentration of each layer of the grain pile; obtain the initial delivery time according to the initial air output rate of the air distribution points and the mixed gas ratio; and deliver the phosphine mixed gas into the fumigation chamber for a specified time according to the mixed gas ratio. Step S3: Set up monitoring points at each gas distribution point to monitor phosphine concentration; set a monitoring time period and monitor the phosphine concentration at each monitoring point in real time during the monitoring time period to obtain phosphine concentration change data at each monitoring point; obtain the gas flow path in the fumigation chamber based on the phosphine concentration change data; adjust each gas distribution point according to the gas flow path.

[0009] As a further aspect of the present invention: the process of acquiring the experimental data includes: A unit volume of grain is collected and denoted as a unit grain pile. The number of pests in each unit grain pile is obtained. Several phosphine concentration values ​​are set, and a phosphine mixture of each concentration value is used to fumigate the unit grain pile. The survival rate of pests in the unit grain pile after fumigation is obtained.

[0010] As a further aspect of the present invention: the process of obtaining the survival rate includes: The survival rate Sr = n / Num × 100%, where n is the number of pests surviving in the unit grain pile after fumigation, and Num is the number of pests surviving in the unit grain pile before fumigation.

[0011] As a further aspect of the present invention: the process for obtaining the optimal phosphine concentration includes: Select all grain piles that have been fumigated with the same phosphine concentration value and record them as grain piles with the same concentration. Obtain the survival rate of each grain pile with the same concentration and obtain the average value of each survival rate, which is recorded as the average survival rate of the phosphine concentration value. Select the phosphine concentration value with the lowest average survival rate and record it as the optimal phosphine concentration per unit volume of grain.

[0012] As a further aspect of the present invention: the air distribution point includes an air inlet and an air outlet, the air inlet being used to deliver phosphine mixed gas into the fumigation chamber, and the air outlet being used to discharge the phosphine mixed gas from the fumigation chamber.

[0013] As a further aspect of the present invention: the process of obtaining the initial transport time includes: The required phosphine concentrations of each layer of the grain pile are summed to obtain the required total concentration c of the grain pile. 总 Using the volume of the chamber as the volume of carbon dioxide in the phosphine mixture, the volume of phosphine in the phosphine mixture, V, is obtained. 磷烷 =V 仓 ×c 总 V 仓 Let V be the volume of the silo, and the proportion of the phosphine mixture obtained be V. 磷烷 V 仓 ; The initial gas output rate represents the volume of phosphine mixture delivered to the fumigation chamber from the gas distribution point per unit time; based on the initial gas output rate v0, the delivery time T=V 仓 / v0.

[0014] As a further aspect of the present invention: the process of obtaining the gas flow path includes: Based on the phosphine concentration change data, the concentration gradient Cg = C / L of the monitoring point in three gradient directions is obtained, where C is the concentration difference between the monitoring point and its adjacent monitoring point in the gradient direction, and L is the distance between the monitoring point and its adjacent monitoring point in the gradient direction. The gradient direction is the direction from high concentration to low concentration along the coordinate axis, and the coordinate axis direction is the direction of the X-axis, Y-axis, and Z-axis in the coordinate system. The concentration gradient at each monitoring point is converted into a three-dimensional vector using a visualization tool to obtain the airflow vector field in the fumigation chamber. In the airflow vector field, the coordinates of the position with the highest phosphine concentration are obtained and recorded as the high concentration source. Starting from the high concentration source, the airflow trajectory is gradually traced along the gradient direction to generate a gas flow path.

[0015] As a further aspect of the present invention: the process of adjusting each air distribution point includes: After the monitoring period ends, the starting point of the airflow trajectory in the fumigation chamber is determined according to the gas flow path, and the layer of the grain pile corresponding to the starting point of the airflow trajectory is obtained and recorded as the source layer. Each monitoring point in the source layer is obtained and recorded as an intra-layer monitoring point; the phosphine concentration at each intra-layer monitoring point is obtained and recorded as the current phosphine concentration; the current phosphine concentration is compared with the required phosphine concentration of the layer to obtain a comparison result; the gas distribution point at the intra-layer monitoring point adjusts the phosphine concentration at the intra-layer monitoring point according to the comparison result; The comparison result is the concentration difference between the current phosphine concentration and the required phosphine concentration. If the current phosphine concentration is lower than the required phosphine concentration, the phosphine mixture is delivered through the outlet according to the concentration difference; if the current phosphine concentration exceeds the required phosphine concentration, the phosphine mixture is discharged through the exhaust port according to the concentration difference. Based on the gas flow path, predict the phosphine concentration at the remaining monitoring points along the gradient direction where the monitoring point in the layer is located, and denote it as the predicted phosphine concentration; compare the predicted phosphine concentration with the required phosphine concentration corresponding to the monitoring point, and adjust the predicted phosphine concentration.

[0016] A control system for using a phosphine mixture for grain fumigation, comprising: Optimal concentration calibration module: acquires experimental data, and based on the experimental data, obtains the optimal phosphine concentration required per unit volume of grain; acquires the grain pile in the fumigation chamber, divides the grain pile longitudinally into several layers, and obtains the volume of each layer of the grain pile; based on the volume of the grain pile layer and the optimal phosphine concentration, obtains the required phosphine concentration for each layer of the grain pile. Mixed gas ratio determination module: Several gas distribution points are set at equal intervals in the fumigation chamber, the volume of the fumigation chamber is obtained, and the mixed gas ratio is obtained according to the required phosphine concentration of each layer of the grain pile; the initial delivery time is obtained according to the initial gas output rate of the gas distribution points and the mixed gas ratio; and the phosphine mixed gas is delivered into the fumigation chamber for a specified time according to the mixed gas ratio. Concentration adjustment module: Monitoring points are set at each gas distribution point to monitor phosphine concentration; a monitoring time period is set, and the phosphine concentration at each monitoring point is monitored in real time during the monitoring time period to obtain phosphine concentration change data at each monitoring point; the gas flow path in the fumigation chamber is obtained based on the phosphine concentration change data; and the gas distribution points are adjusted according to the gas flow path.

[0017] The beneficial effects of this invention are: This invention determines the optimal phosphine concentration through experimental data, calculates the required concentration for each layer of the grain pile layer, ensuring precise fumigant dosage. This avoids both insufficient concentration leading to insecticidal ineffectiveness and excessive concentration causing safety hazards. Dynamic monitoring and adjustment of the phosphine concentration, combined with gas flow path analysis, achieves uniform fumigation, significantly improving pest control efficiency. The use of a premixed gas of phosphine and carbon dioxide avoids the instability of traditional aluminum phosphide on-site reactions, reducing the risk of explosion. Real-time feedback and adjustment at gas distribution and monitoring points prevent localized concentration exceedances, ensuring the safety of storage facilities and operators. Direct use of the mixed gas avoids solid waste generation, reducing solid waste treatment costs and environmental pollution. Optimized gas delivery ratios and times reduce phosphine waste and lower overall fumigation costs. This invention boasts a high degree of automation, using three-dimensional airflow vector field visualization analysis to quickly locate and automatically adjust areas of abnormal concentration, reducing manual intervention. Historical data supports predictive adjustments, improving the stability and repeatability of the fumigation process. Through scientific calculation, real-time monitoring, and dynamic adjustment, this invention achieves high efficiency, safety, and environmental friendliness in phosphine fumigation, providing an innovative solution for pest control in grain storage. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic flowchart of a control method for using a phosphine mixed gas for grain fumigation according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 As shown, the present invention provides a method for controlling the use of phosphine mixed gas in grain fumigation, comprising the following steps: Step S1: Obtain a unit volume of grain, denoted as a unit grain pile, and obtain the number of pests in each unit grain pile; set several phosphine concentration values, and fumigate the unit grain pile with a phosphine mixture of each phosphine concentration value, and obtain the survival rate of pests in the unit grain pile after fumigation to obtain experimental data; based on the experimental data, obtain the optimal phosphine concentration required per unit volume of grain. Obtain the grain pile inside the fumigation chamber, divide the grain pile longitudinally into several layers, obtain the grain volume of each layer of the grain pile, and record it as the grain pile layer volume; based on the grain pile layer volume and the optimal phosphine concentration, obtain the required phosphine concentration for each layer of the grain pile; In a preferred embodiment of the present invention, the process of setting the phosphine concentration value includes: An initial concentration of phosphine is set, and a concentration interval threshold is set. The initial concentration is increased or decreased according to the concentration interval threshold to obtain several phosphine concentration values. In a preferred embodiment of the present invention, the process of obtaining the survival rate includes: The survival rate Sr = n / Num × 100%, where n is the number of pests surviving in the unit grain pile after fumigation, and Num is the number of pests surviving in the unit grain pile before fumigation. In a preferred embodiment of the present invention, the process of obtaining the optimal phosphine concentration includes: Select all grain piles that were fumigated with the same phosphine concentration value and record them as grain piles with the same concentration. Obtain the survival rate of each grain pile with the same concentration and obtain the average value of each survival rate, which is recorded as the average survival rate of the phosphine concentration value. Select the phosphine concentration value with the lowest average survival rate and record it as the optimal phosphine concentration per unit volume of grain. Understandably, the concentration with the lowest average survival rate is chosen as the optimal phosphine concentration to ensure maximum insecticidal efficiency. In a preferred embodiment of the present invention, the process of obtaining the required phosphine concentration for each layer of the grain pile includes the following: the required phosphine concentration Rcp = V × Ocp, where Ocp represents the optimal phosphine concentration and V represents the volume of the grain pile layer. Understandably, by setting different phosphine concentrations and conducting fumigation experiments on a unit grain pile (fixed volume grain sample), the survival rate of pests is recorded, and a quantitative relationship between phosphine concentration and insecticidal effect is established. This avoids the inaccuracy of estimating concentration based on experience in traditional fumigation, and ensures through experimental data that the amount of phosphine used is both highly effective in killing pests and does not exceed the safety threshold. Furthermore, the distribution of phosphine is dynamically adjusted according to the characteristics of different layers of the grain pile (e.g., the bottom layer is dense, the top layer is loose), improving the overall uniformity of fumigation and reducing blind spots. Step S2: Several air distribution points are set at equal intervals in the fumigation chamber. Each air distribution point includes an air inlet and an air outlet. The air inlet is used to deliver phosphine mixed gas into the fumigation chamber, and the air outlet is used to discharge the phosphine mixed gas from the fumigation chamber. The volume of the fumigation chamber is obtained and recorded as the chamber volume. The mixed gas ratio is obtained according to the required phosphine concentration of each layer of the grain pile. The initial delivery time T is obtained according to the initial gas output rate of the gas distribution point and the mixed gas ratio. The phosphine mixed gas is delivered into the fumigation chamber for a time T according to the mixed gas ratio. In a preferred embodiment of the present invention, the process of setting a plurality of air distribution points at equal intervals in the fumigation chamber includes: Set an air distribution interval threshold, and divide the wall of the fumigation chamber into equally spaced grids according to the air distribution interval threshold. Obtain all the intersection points in the grid and record them as air distribution points. In a preferred embodiment of the present invention, the process of obtaining the mixture ratio includes: The required phosphine concentrations of each layer of the grain pile are summed to obtain the required total concentration c of the grain pile. 总 Using the volume of the chamber as the volume of carbon dioxide in the phosphine mixture, the volume of phosphine in the phosphine mixture, V, is obtained. 磷烷 =V 仓 ×c 总 V 仓 Let V be the volume of the silo, and the proportion of the phosphine mixture obtained be V. 磷烷 V 仓 ; In a preferred embodiment of the present invention, the process of obtaining the initial delivery time includes: The initial gas output rate represents the volume of phosphine mixture delivered to the fumigation chamber from the gas distribution point per unit time; based on the initial gas output rate v0, the delivery time T=V 仓 / v0; It is understandable that gas distribution points (inlets and outlets) are set at equal intervals in the fumigation chamber to form a gas circulation network, ensuring that the phosphine mixture is evenly diffused to all areas of the grain pile; the mixture is injected through the inlet and the residual gas is discharged through the outlet to maintain dynamic airflow balance and avoid local concentrations that are too high or too low; the mixture is delivered at this time to ensure that the total amount of gas is precisely matched with the needs of the grain pile. It is worth noting that the lower explosive limit (LEL) and toxicity limit of phosphine are determined through preliminary experiments, and a safe concentration threshold is set. When calculating the required total concentration, the safety database is compared to ensure that the required total concentration is less than the safe concentration threshold. If the threshold is exceeded, an alarm is triggered and the concentration of each layer is automatically reduced. At the same time, the carbon dioxide content in the phosphine mixture is ≥60%, and inert gas is used to suppress the risk of phosphine combustion and explosion. Step S3: Set up monitoring points at each gas distribution point to monitor phosphine concentration; set a monitoring time period, and monitor the phosphine concentration at each monitoring point in real time during the monitoring time period to obtain phosphine concentration change data at each monitoring point; obtain the gas flow path in the fumigation chamber based on the phosphine concentration change data; adjust each gas distribution point according to the gas flow path. In a preferred embodiment of the present invention, the process of setting the monitoring time period includes: Acquire historical fumigation data, which includes the stable consumption time in the fumigation chamber when grain is fumigated in the past. The stable consumption time is the time elapsed from the initial moment to the stable moment. The initial moment is the moment when the phosphine mixture is delivered and the stable moment is the moment when the phosphine concentration at each monitoring point in the fumigation chamber remains unchanged. The maximum value of each stable consumption time in the historical fumigation data is obtained and recorded as the duration; the initial time in the fumigation chamber is obtained and recorded as the current initial time; and the monitoring time period is obtained based on the current initial time and the duration. In a preferred embodiment of the present invention, the phosphine concentration change data includes real-time monitoring of the phosphine concentration at each monitoring point, and the location coordinates of each monitoring point. The process of obtaining the location coordinates of the monitoring point includes: Choose any intersection point in the grid within the fumigation chamber as the origin, establish a coordinate system, and obtain the coordinates of the monitoring point on the coordinate system, which are recorded as the position coordinates. In a preferred embodiment of the present invention, the process of obtaining the gas flow path includes: Based on the phosphine concentration change data, the concentration gradient Cg = C / L of the monitoring point in three gradient directions is obtained, where C is the concentration difference between the monitoring point and its adjacent monitoring point in the gradient direction, and L is the distance between the monitoring point and its adjacent monitoring point in the gradient direction; the gradient direction is the direction from high concentration to low concentration along the coordinate axis, and the coordinate axis direction is the direction of the X-axis, Y-axis, and Z-axis in the coordinate system; the concentration gradient at each monitoring point is converted into a three-dimensional vector using a visualization tool to obtain the airflow vector field in the fumigation chamber; in the airflow vector field, the coordinates of the position with the highest phosphine concentration are obtained and recorded as the high concentration source, and the airflow trajectory is gradually traced along the gradient direction from the high concentration source to generate a gas flow path; In a preferred embodiment of the present invention, the process of adjusting each air distribution point includes: After the monitoring period ends, the starting point of the airflow trajectory in the fumigation chamber is determined according to the gas flow path, and the layer of the grain pile corresponding to the starting point of the airflow trajectory is obtained and recorded as the source layer. Each monitoring point in the source layer is obtained and recorded as an intra-layer monitoring point; the phosphine concentration at each intra-layer monitoring point is obtained and recorded as the current phosphine concentration; the current phosphine concentration is compared with the required phosphine concentration of the layer to obtain a comparison result; the gas distribution point at the intra-layer monitoring point adjusts the phosphine concentration at the intra-layer monitoring point according to the comparison result; Based on the gas flow path, predict the phosphine concentration at the remaining monitoring points along the gradient direction where the monitoring point in the layer is located, and denote it as the predicted phosphine concentration; compare the predicted phosphine concentration with the required phosphine concentration corresponding to the monitoring point, and adjust the predicted phosphine concentration accordingly; The process of adjusting the phosphine concentration at the monitoring points within the layer includes: The comparison result is the concentration difference between the current phosphine concentration and the required phosphine concentration. If the current phosphine concentration is lower than the required phosphine concentration, the phosphine mixture is delivered through the outlet according to the concentration difference; if the current phosphine concentration exceeds the required phosphine concentration, the phosphine mixture is discharged through the exhaust port according to the concentration difference. It should be noted that the process of adjusting the predicted phosphine concentration is the same as the process of adjusting the phosphine concentration at the monitoring point within the layer, and will not be described in detail here. Understandably, by using reverse airflow trajectory tracking technology, the source layer of gas diffusion can be accurately located; It is worth noting that the gas discharged from the exhaust port enters the buffer storage tank after passing through the catalytic purification unit (removing pest metabolic products) to obtain circulating gas; the concentration of phosphine in the circulating gas is detected in real time by a gas component analyzer, and the amount of fresh mixed gas to be replenished is calculated based on the real-time concentration difference, and the mixing ratio of new and old gases is controlled to ensure that the mixed gas in the circulating gas is always at the mixed gas ratio; the phosphine mixed gas delivered by the exhaust port includes the circulating gas.

[0022] A control system for using a phosphine mixture for grain fumigation, comprising: Optimal concentration calibration module: acquires experimental data, and based on the experimental data, obtains the optimal phosphine concentration required per unit volume of grain; acquires the grain pile in the fumigation chamber, divides the grain pile longitudinally into several layers, and obtains the volume of each layer of the grain pile; based on the volume of the grain pile layer and the optimal phosphine concentration, obtains the required phosphine concentration for each layer of the grain pile. Mixed gas ratio determination module: Several gas distribution points are set at equal intervals in the fumigation chamber, the volume of the fumigation chamber is obtained, and the mixed gas ratio is obtained according to the required phosphine concentration of each layer of the grain pile; the initial delivery time is obtained according to the initial gas output rate of the gas distribution points and the mixed gas ratio; and the phosphine mixed gas is delivered into the fumigation chamber for a specified time according to the mixed gas ratio. Concentration adjustment module: Monitoring points are set at each gas distribution point to monitor phosphine concentration; a monitoring time period is set, and the phosphine concentration at each monitoring point is monitored in real time during the monitoring time period to obtain phosphine concentration change data at each monitoring point; the gas flow path in the fumigation chamber is obtained based on the phosphine concentration change data; and the gas distribution points are adjusted according to the gas flow path.

[0023] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for controlling the use of phosphine mixed gas in grain fumigation, characterized in that, Includes the following steps: Step S1: Obtain experimental data; based on the experimental data, obtain the optimal phosphine concentration required per unit volume of grain; obtain the grain pile in the fumigation chamber, divide the grain pile longitudinally into several layers, and obtain the volume of each layer of the grain pile; based on the volume of the grain pile layer and the optimal phosphine concentration, obtain the required phosphine concentration for each layer of the grain pile. Step S2: Set several air distribution points at equal intervals in the fumigation chamber, obtain the volume of the fumigation chamber, and obtain the mixed gas ratio according to the required phosphine concentration of each layer of the grain pile; obtain the initial conveying time according to the initial air output rate of the air distribution points and the mixed gas ratio. According to the specified gas mixture ratio, a phosphine mixture is supplied to the fumigation chamber for a specified period of time. Step S3: Set up monitoring points at each gas distribution point to monitor phosphine concentration; set a monitoring time period, and monitor the phosphine concentration at each monitoring point in real time during the monitoring time period to obtain phosphine concentration change data at each monitoring point; obtain the gas flow path in the fumigation chamber based on the phosphine concentration change data; adjust each gas distribution point according to the gas flow path.

2. The method for controlling the use of phosphine mixed gas for grain fumigation according to claim 1, characterized in that, In step S1, the process of acquiring the experimental data includes: A unit volume of grain is collected and denoted as a unit grain pile. The number of pests in each unit grain pile is obtained. Several phosphine concentration values ​​are set, and a phosphine mixture of each concentration value is used to fumigate the unit grain pile. The survival rate of pests in the unit grain pile after fumigation is obtained.

3. The method for controlling the use of phosphine mixed gas for grain fumigation according to claim 2, characterized in that, In step S1, the process of obtaining the survival rate includes: The survival rate Sr = n / Num × 100%, where n is the number of pests surviving in the unit grain pile after fumigation, and Num is the number of pests surviving in the unit grain pile before fumigation.

4. The method for controlling the use of phosphine mixed gas for grain fumigation according to claim 2, characterized in that, In step S1, the process of obtaining the optimal phosphine concentration includes: Select all grain piles that have been fumigated with the same phosphine concentration value and record them as grain piles with the same concentration. Obtain the survival rate of each grain pile with the same concentration and obtain the average value of each survival rate, which is recorded as the average survival rate of the phosphine concentration value. Select the phosphine concentration value with the lowest average survival rate and record it as the optimal phosphine concentration per unit volume of grain.

5. The method for controlling the use of phosphine mixed gas for grain fumigation according to claim 1, characterized in that, In step S2, the air distribution point includes an air inlet and an air outlet. The air inlet is used to deliver phosphine mixed gas into the fumigation chamber, and the air outlet is used to discharge the phosphine mixed gas from the fumigation chamber.

6. The method for controlling the use of phosphine mixed gas for grain fumigation according to claim 1, characterized in that, In step S2, the process of obtaining the initial delivery time includes: The required phosphine concentrations of each layer of the grain pile are summed to obtain the required total concentration c of the grain pile. 总 Using the volume of the chamber as the volume of carbon dioxide in the phosphine mixture, the volume of phosphine in the phosphine mixture, V, is obtained. 磷烷 =V 仓 ×c 总 V 仓 Let V be the volume of the silo, and the proportion of the phosphine mixture obtained be V. 磷烷 V 仓 ; The initial gas output rate represents the volume of phosphine mixture delivered to the fumigation chamber from the gas distribution point per unit time; based on the initial gas output rate v0, the delivery time T=V 仓 / v0.

7. The method for controlling the use of phosphine mixed gas for grain fumigation according to claim 1, characterized in that, In step S3, the process of obtaining the gas flow path includes: Based on the phosphine concentration change data, the concentration gradient Cg = C / L of the monitoring point in three gradient directions is obtained, where C is the concentration difference between the monitoring point and its adjacent monitoring point in the gradient direction, and L is the distance between the monitoring point and its adjacent monitoring point in the gradient direction. The gradient direction is the direction from high concentration to low concentration along the coordinate axis, and the coordinate axis direction is the direction of the X-axis, Y-axis, and Z-axis in the coordinate system. The concentration gradient at each monitoring point is converted into a three-dimensional vector using a visualization tool to obtain the airflow vector field in the fumigation chamber. In the airflow vector field, the coordinates of the position with the highest phosphine concentration are obtained and recorded as the high concentration source. Starting from the high concentration source, the airflow trajectory is gradually traced along the gradient direction to generate a gas flow path.

8. The method for controlling the use of phosphine mixed gas for grain fumigation according to claim 5, characterized in that, In step S3, the process of adjusting each air distribution point includes: After the monitoring period ends, the starting point of the airflow trajectory in the fumigation chamber is determined according to the gas flow path, and the layer of the grain pile corresponding to the starting point of the airflow trajectory is obtained and recorded as the source layer. Each monitoring point in the source layer is obtained and recorded as an intra-layer monitoring point; the phosphine concentration at each intra-layer monitoring point is obtained and recorded as the current phosphine concentration; the current phosphine concentration is compared with the required phosphine concentration of the layer to obtain a comparison result; the gas distribution point at the intra-layer monitoring point adjusts the phosphine concentration at the intra-layer monitoring point according to the comparison result; The comparison result is the concentration difference between the current phosphine concentration and the required phosphine concentration. If the current phosphine concentration is lower than the required phosphine concentration, the phosphine mixture is delivered through the outlet according to the concentration difference; if the current phosphine concentration exceeds the required phosphine concentration, the phosphine mixture is discharged through the exhaust port according to the concentration difference. Based on the gas flow path, predict the phosphine concentration at the remaining monitoring points along the gradient direction where the monitoring point in the layer is located, and denote it as the predicted phosphine concentration; compare the predicted phosphine concentration with the required phosphine concentration corresponding to the monitoring point, and adjust the predicted phosphine concentration.

9. A control system for using a phosphine mixture for grain fumigation, characterized in that, include: Optimal concentration calibration module: acquires experimental data, and based on the experimental data, obtains the optimal phosphine concentration required per unit volume of grain; acquires the grain pile in the fumigation chamber, divides the grain pile longitudinally into several layers, and obtains the volume of each layer of the grain pile; based on the volume of the grain pile layer and the optimal phosphine concentration, obtains the required phosphine concentration for each layer of the grain pile. Mixed gas ratio determination module: Several gas distribution points are set at equal intervals in the fumigation chamber, the volume of the fumigation chamber is obtained, and the mixed gas ratio is obtained according to the required phosphine concentration of each layer of the grain pile; the initial conveying time is obtained according to the initial gas output rate of the gas distribution points and the mixed gas ratio. According to the specified gas mixture ratio, a phosphine mixture is supplied to the fumigation chamber for a specified period of time. Concentration adjustment module: Monitoring points are set at each gas distribution point to monitor phosphine concentration; a monitoring time period is set, and the phosphine concentration at each monitoring point is monitored in real time during the monitoring time period to obtain phosphine concentration change data at each monitoring point; the gas flow path in the fumigation chamber is obtained based on the phosphine concentration change data; and the gas distribution points are adjusted according to the gas flow path.

Images