Device and method for low-temperature controlled atmosphere pest killing

Abstract

The invention relates to the technical field of warehouse controlled atmosphere insect killing, in particular to a low-temperature controlled atmosphere insect killing device and method.The low-temperature controlled atmosphere insect killing device comprises a nitrogen making device, a mixing heat insulation chamber and a sealed warehouse which are sequentially connected in the air inlet direction, and the mixing heat insulation chamber is connected with a dry ice feeder; temperature control valves are arranged at the discharging end of the dry ice feeder and the gas outlet end of the nitrogen making device respectively, the feeding amount of dry ice and the gas inlet amount of nitrogen are controlled through the temperature control valves, the nitrogen is cooled through the dry ice, and the dry ice and the nitrogen form mixed modified atmosphere gas with the temperature lower than 10 DEG C and then enter the sealed warehouse; the oxygen concentration in the sealed warehouse is reduced to be smaller than or equal to 2% through the introduced mixed modified atmosphere gas, and the low-oxygen environment is maintained within 15 days. The low-oxygen environment formed by low-temperature and high-concentration nitrogen and carbon dioxide has a synergistic killing effect on grain or tobacco insect pests in the closed warehouse, and the treatment time of controlled atmosphere pest and disease killing is remarkably shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of controlled atmosphere pest control in warehouses, and in particular to a low-temperature controlled atmosphere pest control device and method. Background Art

[0002] The traditional method for pest control in stored materials like tobacco leaves and grain is biannual phosphine (PH3) fumigation. However, as tobacco beetles become increasingly resistant to phosphine fumigation, phosphine fumigation has the problem of incomplete pest control. Furthermore, phosphine is a flammable, explosive, and highly toxic substance that not only corrodes metal equipment but also poses significant safety and environmental risks.

[0003] In recent years, the use of nitrogen or nitrogen mixed with other rare gases for fumigation and pest control has rapidly developed. This technology, a green tobacco storage and maintenance technique, has gradually developed in recent years. Its main principle is to change the gas composition of the storage environment by injecting gases such as N2 or CO2, maintaining a low-oxygen state and suffocating tobacco pests. This nitrogen-filled, oxygen-reducing atmosphere is controlled by using specialized nitrogen generators to generate high-concentration nitrogen. This is then injected into a sealed container constructed of a specialized, high-barrier film. This method regulates the oxygen and carbon dioxide concentrations, as well as the relative humidity, within the sealed storage space to ensure safe tobacco storage.

[0004] In closed warehouses with small volumes, densely packed contents, and relatively low air volumes, nitrogen generation equipment operates relatively smoothly and normally. However, in closed warehouses with limited pest control time and large volumes (such as tobacco leaf storage vaults), the equipment must process a large volume of air, resulting in high loads and long periods of operation, significantly increasing the difficulty of nitrogen filling and air conditioning operations and the control of the equipment system. Furthermore, existing nitrogen filling and oxygen reduction methods for pest control take a long time. For example, in "Tests on the Application of Temperature-Controlled Nitrogen Air Conditioning for Insecticide," Lu Zongxi, Zhang Huayang, and Dong Yuantang reported that maintaining a 98% nitrogen concentration for 40 days achieved excellent pest control results. In "Experiments on the Control of Tobacco Beetles with Nitrogen Air Conditioning," Liu Jun reported that, when the ambient temperature was above 30°C, nitrogen filling and oxygen reduction to 1% oxygen for 20 days, or 2% oxygen for 30 days, achieved 100% mortality for both adult and larval tobacco beetles within tobacco stacks.

[0005] Chinese invention patent number CN113854350A discloses a method for improving the effect of controlled atmosphere and insect prevention in a closed chamber by relying on the sublimation effect of dry ice. The closed chamber is connected to the deoxygenation and nitrogen production equipment through a gas input pipe and a gas exhaust pipe to form a circulating deoxygenation and nitrogen filling system. At the same time, a "pressure equalization system" including flexible air bags inside and outside the chamber is constructed. Dry ice is introduced into the flexible air bag as a carbon dioxide gas source. When the deoxygenation and nitrogen production equipment is turned on to extract air from the closed chamber and separate it into oxygen and nitrogen, the volume of the air bag expands due to the sublimation of dry ice. Firstly, the pressure inside and outside the chamber is balanced during the operation of the circulating deoxygenation and nitrogen filling system. Secondly, the carbon dioxide inside the air bag is mechanically released into the closed chamber in a seamless manner, realizing the dual functions of "pressure equalization and load reduction" and "mechanical release" of carbon dioxide gas in the circulating nitrogen filling and insect prevention mode of the entire chamber. This insect repellent combines the dual oxygen-reducing effects of carbon dioxide and nitrogen, but its structure is complex and requires dry ice to be put into a closed compartment, which is not conducive to the sealing of the closed compartment. It also has a single effect on disinfecting pests in the closed space and takes a long time to kill insects.

[0006] According to the pest control needs of large-capacity warehouses such as tobacco warehouses, how to quickly achieve a low-oxygen environment in a closed warehouse environment and effectively shorten the fumigation and pest control time is a technical problem that needs to be solved urgently. Summary of the Invention

[0007] To solve the above problems, the present application provides a low-temperature controlled atmosphere pest control device and method, which uses dry ice to quickly cool nitrogen and form a mixed controlled atmosphere gas to shorten the low-oxygen environment ventilation time and pest control treatment time in a closed warehouse.

[0008] The technical solution adopted by the present invention to solve the technical problem is: The present application provides a low-temperature controlled atmosphere insecticide device, comprising a nitrogen generator, a mixing insulation chamber, and a sealed warehouse connected in sequence along the air inlet direction, wherein the mixing insulation chamber is connected to a dry ice feeder, and a discharge end of the dry ice feeder and an air outlet end of the nitrogen generator are respectively provided with temperature control valves, through which the feed amount of dry ice and the intake amount of nitrogen are controlled, and a mixed atmosphere of dry ice and nitrogen is formed in the mixing insulation chamber and introduced into the sealed warehouse.

[0009] As an improvement to the above solution, the nitrogen generator is connected to the mixing insulation chamber through a connecting pipe, the mixing insulation chamber is connected to the sealed warehouse through an air inlet pipe, and the air outlet end of the sealed warehouse is connected to the nitrogen generator through an exhaust pipe; The temperature control valve is arranged on the connecting pipe, and the air inlet pipe and the exhaust pipe are both provided with an electromagnetic control valve and a one-way check valve; The air inlet pipe is also provided with a temperature detector for detecting the temperature of the mixed gas entering the closed warehouse.

[0010] As an improvement to the above solution, a temperature sensor and a gas detector are provided in the sealed warehouse.

[0011] As an improvement to the above solution, the discharge end of the dry ice feeder extends into the interior of the mixing insulation chamber and is provided with a filter screen at its end, the bottom surface of the filter screen protrudes downward in a semi-rugby ball shape.

[0012] As an improvement to the above solution, the output end of the air inlet pipe is installed at the bottom of the sealed warehouse, and the input end of the exhaust pipe is installed at the top of the sealed warehouse.

[0013] As an improvement of the above-mentioned scheme, the dry ice feeder includes an insulation sealing cylinder, a sealing cover is provided on the top of the insulation sealing cylinder, a sealing valve plate is provided in the middle of the insulation sealing cylinder, the sealing valve plate divides the inner cavity of the insulation sealing cylinder into a feeding cavity and a discharging cavity, the middle part of the sealing valve plate is transmission-connected with a rotating shaft, one end of the rotating shaft extends to the outside of the insulation sealing cylinder and is provided with an operating handle, and the bottom end of the discharging cavity is connected to the mixing insulation chamber.

[0014] As an improvement of the above solution, the thermal insulation sealing cylinder includes an inner cylinder, and the outer wall surface of the inner cylinder is sequentially wrapped with a thermal insulation layer and an outer shell provided with a vacuum interlayer.

[0015] The present application also provides a low-temperature controlled atmosphere pest control method, which is applied to any of the low-temperature controlled atmosphere pest control devices described above. Dry ice is used to cool the nitrogen, so that a mixed gas formed by dry ice and nitrogen enters a sealed warehouse. The introduced mixed gas reduces the oxygen concentration in the sealed warehouse to ≤2% and maintains a low-oxygen environment for no more than 15 days; the temperature of the mixed gas is lower than 10°C.

[0016] When the temperature of the mixed gas is lower than 10°C, the low temperature will reduce the enzyme activity in the pests, thereby affecting their normal physiological and biochemical reaction rates, slowing down their metabolic activities, and prolonging their development cycle, thereby significantly affecting the physiology of tobacco pests. Based on the effect of low temperature on tobacco pests, the inventors have proposed an improvement to the existing gas-conditioning method for tobacco leaves. Dry ice is used to quickly cool the nitrogen used in the gas-conditioning, which will increase the density of the nitrogen entering the closed warehouse. The carbon dioxide gas formed after the dry ice is vaporized can also be quickly mixed with the nitrogen and then enter the closed warehouse, further increasing the density of the mixed gas-conditioning gas. Therefore, the cooled mixed gas-conditioning gas will sink and accumulate at the bottom of the closed warehouse, thereby promoting the air in the closed warehouse to be discharged from the top of the closed warehouse. Compared with the existing gas-conditioning method that uses nitrogen filling and / or carbon dioxide to reduce oxygen at room temperature, the gas replacement efficiency is significantly improved, and the ventilation cycle for reaching a low-oxygen environment in the gas-conditioning method is shortened. Secondly, the cooled mixed gas is transported and filled into a closed warehouse, which will lower the temperature inside the closed warehouse, thereby enhancing the physiological inhibition of the low-oxygen environment on tobacco pests, accelerating the damage to the cell structure and the imbalance of water balance, etc., and promoting the disinfecting effect of low oxygen on tobacco pests. The applicant has verified through experiments that: low temperature and low oxygen environment have a significant synergistic promoting effect on the disinfecting effect of tobacco pests, further shortening the action cycle of low oxygen conditioning.

[0017] As an improvement to the above solution, the following steps are included: Step 1: Preset a target temperature value T of the mixed gas formed by dry ice and nitrogen; wherein the target temperature value is ≤5°C; Step 2: Obtain the mass ratio of the dry ice and nitrogen mixture according to the target temperature value T; Step 3: A mixed gas is formed according to the mass ratio of dry ice and nitrogen. The nitrogen is cooled with dry ice and properly regulated so that the mixed gas reaches the preset target temperature before entering the sealed warehouse. Step 4: The mixed gas introduced will reduce the oxygen concentration in the sealed warehouse to ≤2% and maintain the low oxygen environment for less than 8 days.

[0018] As an improvement to the above solution, in step 2, the mass ratio of dry ice to nitrogen is calculated as follows: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)] Wherein, C1 is the specific heat capacity of nitrogen = 1.040 J / g·°C, T1 is the temperature of nitrogen (in this embodiment, the nitrogen temperature is room temperature 25°C), γ is the latent heat of vaporization of dry ice = 335 kJ / kg, and C2 is the specific heat capacity of dry ice particles = 0.846 J / (g·°C).

[0019] As an improvement to the above scheme, considering that both carbon dioxide and nitrogen can be used as controlled atmosphere gases (CAGs) simultaneously, the two can work together, and combined with practical experience in controlled atmosphere pest control with tobacco leaves, the temperature of the mixed CAG gas is controlled by controlling the mass ratio of dry ice to nitrogen. The mass ratio of dry ice and nitrogen mixed in the mixing insulation chamber is controlled between 1:15 and 1:40. Specifically, when the mass ratio of dry ice to nitrogen is 1:15, the temperature of the nitrogen is at room temperature, 25°C, and the preset temperature of the mixed CAG gas is 0°C. When the mass ratio of dry ice to nitrogen is 1:40, the temperature of the nitrogen is 10°C, and the preset temperature of the mixed CAG gas is 0°C.

[0020] The beneficial effects brought by the present invention are: The present application provides a method for low-temperature controlled atmosphere pest control, which uses dry ice to quickly cool nitrogen and form a mixed controlled atmosphere, so that the density of the mixed controlled atmosphere increases and is greater than the density of the residual air in the closed warehouse. The mixed controlled atmosphere introduced from the bottom of the closed warehouse quickly accumulates at the bottom of the closed warehouse and squeezes the residual air in the closed warehouse to be discharged from the exhaust pipe at the top thereof, thereby accelerating the replacement rate of the mixed controlled atmosphere with the air in the closed warehouse, and shortening the ventilation time of the low-oxygen environment required for controlled atmosphere pest control; compared with the normal temperature nitrogen-filled and oxygen-reduced controlled atmosphere method, due to the decrease in gas temperature, the mixing rate of the filled nitrogen and the residual air is reduced, and the replacement efficiency of the nitrogen and the residual air in the closed warehouse is improved; compared with the method of introducing heated carbon dioxide to achieve a low-oxygen environment in the prior art, it omits the heating gas heater, and reduces the energy consumption and operating costs during the ventilation process of the low-oxygen environment.

[0021] Since low temperatures can slow down the biochemical reactions of pests and diseases, damage cell structures, and inhibit the nervous system, high concentrations of carbon dioxide can cause tobacco pests to suffocate in an oxygen-deficient environment and cause acidosis in the body (such as tobacco beetles), and high concentrations of nitrogen can cause an oxygen-deficient environment, inhibit the biochemical reactions of pests and diseases, and interfere with the nervous system. Therefore, the present invention combines the synergistic disinfecting effect of low temperatures, high concentrations of nitrogen and carbon dioxide to form a low-oxygen environment on grain or tobacco pests in closed warehouses, significantly shortening the processing time for controlled atmosphere pest control.

[0022] The low-temperature controlled atmosphere pest control device provided in this application controls the nitrogen intake and dry ice feed through a temperature control valve, thereby achieving fine control of the temperature in a closed warehouse, accurately controlling the temperature and low-oxygen environment of the low-temperature controlled atmosphere pest control, thereby achieving the purpose of extremely fast controlled atmosphere pest control and significantly shortening the operation time and cost of controlled atmosphere pest control. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attachment Figure 1 Schematic diagram of the structure of the low-temperature controlled atmosphere insecticide device in Example 1; Attachment Figure 2 is a schematic structural diagram of the dry ice feeder in Example 1; Attachment Figure 3 is a bottom view of the gas distribution device in Example 1; Attachment Figure 4 Schematic diagram of the structure of the low-temperature controlled atmosphere insecticide device in Example 7; Attachment Figure 5 It is a structural schematic diagram of the low-temperature controlled atmosphere insecticide device in Example 8.

[0024] In the figure: 1. Nitrogen generator; 2. Connecting pipe; 3. Temperature control valve; 4. Filter; 5. Mixing insulation chamber; 6. Dry ice feeder; 601. Feed chamber; 602. Sealing valve plate; 603. Operating handle; 604. Discharge chamber; 6041. Discharge port; 605. Outer shell; 606. Thermal insulation layer; 607. Inner cylinder; 608. Inner cover; 609. Outer cover; 7. Air inlet pipe; 8. PLC controller; 9. Membrane cover; 10. Insulation cover; 11. Temperature sensor; 12. Exhaust pipe; 13. Gas detector; 14. Bottom membrane; 15. Gas distribution device; 1501. Gas distribution hole; 16. Storage warehouse; 1601. Track for movement of cigarette stack trays; 17. Exhaust device. DETAILED DESCRIPTION

[0025] 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.

[0026] In the description of the present invention, it should be understood that the terms "upper side", "lower side", "upper end", "two ends", "width", "height", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0027] In the present invention, unless otherwise expressly specified or limited, terms such as "disposed," "installed," "connected," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections, mechanical connections, direct connections, or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0028] Example 1 Reference Figure 1-5 A low-temperature controlled atmosphere insecticide device includes a PLC controller 8, and a nitrogen generator 1, a mixing insulation chamber 5, and a sealed warehouse connected in sequence along the air inlet direction. A dry ice feeder 6 is connected above the mixing insulation chamber 5. The discharge end of the dry ice feeder 6 and the air outlet end of the nitrogen generator 1 are respectively provided with a temperature control valve 3. The PLC controller 8 controls the temperature control valve 3, thereby controlling the feeding speed and time of the dry ice, that is, the total feed amount of dry ice, and the intake flow rate of nitrogen, forming a mixed atmosphere of dry ice and nitrogen in the mixing insulation chamber 5 and passing it into the sealed warehouse.

[0029] The nitrogen generator 1 is connected to the mixing and insulating chamber 5 via a connecting pipe 2. The mixing and insulating chamber 5 is connected to the sealed warehouse via an air inlet pipe 7. The air outlet of the sealed warehouse is connected to the nitrogen generator 1 via an exhaust pipe 12, realizing gas recycling. A temperature control valve 3 is provided on the connecting pipe 2 to control the intake of nitrogen. Both the air inlet pipe 7 and the exhaust pipe 12 are provided with an electromagnetic control valve and a one-way check valve. The electromagnetic control valve is electrically connected to a PLC controller 8 and is used to control the transmission speed of the mixed gas into the sealed warehouse and the speed at which the residual gas in the sealed warehouse is discharged, thereby maintaining the air pressure balance in the sealed warehouse.

[0030] A temperature detector is also provided on the air inlet pipe 7, which is connected to the PLC controller 8 and is used to detect the temperature of the mixed gas entering the sealed warehouse. According to the temperature detected by the temperature detector, the feed amount of dry ice and the intake flow rate of nitrogen in the mixing insulation chamber 5 are appropriately adjusted so that the mixed gas reaches the preset target temperature value before entering the sealed warehouse.

[0031] A temperature sensor 11 and a gas detector 13 are provided in the sealed warehouse, and the temperature sensor 11 and the gas detector 13 are electrically connected to the PLC controller 8 .

[0032] The mixing insulation chamber 5 is an insulated container for a mixture of nitrogen and dry ice. The dry ice feeder 6 is connected to the top of the mixing insulation chamber 5 through a pipeline. A temperature control valve 3 is also provided on the pipeline to control the feed amount of dry ice. The discharge end of the pipeline extends to the interior of the mixing insulation chamber 5 and a filter screen 4 is provided at its end. Preferably, the filter screen 4 is a rigid filter screen 4, such as a filter screen 4 made of stainless steel. The bottom surface of the filter screen 4 protrudes downward in a semi-rugby shape, which is convenient for expanding the contact surface area between dry ice and nitrogen, promoting the vaporization of dry ice and mixing with nitrogen to form a uniform mixed gas, and preventing dry ice or dry ice particles from entering the air inlet pipe 7 and sticking to each other and growing larger, thereby blocking the pipeline. A safety valve is provided at the top of the mixing insulation chamber 5 to prevent the internal pressure from being too high.

[0033] The sealed warehouse of this embodiment is a sealed tent for storing tobacco leaves. The sealed tent includes a base film 14 and a film cover 9 covering the base film 14. The base film 14 is sealed to the film cover 9. The outer wall of the film cover 9 is covered with a heat-insulating cover 10.

[0034] Warehouses for materials such as tobacco and grain or the bottom of sealed tents generally contain a large amount of materials, and accordingly, a large number of pests are present in the warehouses or at the bottom of sealed tents. Since the density of carbon dioxide in the mixed gas conditioning is greater than the density of air and the density of nitrogen is slightly less than the density of air (under the same conditions), low-temperature treatment will increase the density of the gas. In this embodiment, the density of the mixed gas conditioning gas after low-temperature treatment is greater than the density of air at room temperature. Therefore, the output end of the air inlet pipe 7 is installed at the bottom of the sealed warehouse, and the input end of the exhaust pipe 12 is installed at the top of the sealed warehouse, realizing low-side inlet and top-side outlet, which is convenient for the mixed gas-conditioned gas after low-temperature treatment to enter from the bottom of the sealed warehouse, so that the carbon dioxide and nitrogen concentrations at the bottom of the sealed tent can reach higher concentrations in a shorter time, accelerating the death time of pests in the sealed and airtight warehouse or sealed tent, shortening the time of pest control, and reducing the cost of pest control; it can also extend the residence time of the low-temperature mixed gas-conditioned gas in the sealed warehouse, and the accumulation of the low-temperature mixed gas-conditioned gas at the bottom of the sealed warehouse accelerates the discharge of the remaining normal temperature air in the sealed warehouse from the top, shortening the ventilation time required for the low-oxygen environment. As the concentrations of carbon dioxide and nitrogen in the sealed warehouse or sealed tent gradually increase, even the insects remaining at high positions will die due to metabolic disorders and other reasons.

[0035] The dry ice feeder 6 includes an insulated sealed cylinder with a sealing cover at the top and a sealing valve plate 602 at the center. This valve plate 602 divides the cylinder's interior into a feed chamber 601 and a discharge chamber 604. A rotating shaft is connected to the center of the valve plate 602, one end of which extends outward from the cylinder and connects to an operating handle 603. The arrangement of the shaft and operating handle 603 allows the operator to easily control the opening and closing of the valve plate 602, thereby feeding and discharging dry ice. A discharge port 6041, connected to a pipeline, is located at the bottom of the discharge chamber 604. The thermal insulation cylinder comprises an inner cylinder 607, the outer wall of which is sequentially wrapped with a thermal insulation layer 606 and an outer shell 605 with a vacuum interlayer. The sealing cover comprises an inner cover 608, which is sealed to the inner cylinder 607, and an outer cover 609, which covers the top of the outer shell 605. The inner and outer covers 608 and 609 are fixedly connected and integral. The thermal insulation layer 606 is made of an insulating material such as rock wool, aluminum silicate felt, or glass wool felt, with a thermal conductivity of ≤0.03 W / (m·k).

[0036] The air inlet pipe 7 extends into the sealed warehouse, and a gas distribution device 15 is provided at its output end. The gas distribution device 15 is provided with gas distribution holes 1501 toward the bottom of the sealed warehouse.

[0037] Example 2 This embodiment provides a method for killing insects with a low-temperature controlled atmosphere, which is applied to the low-temperature controlled atmosphere pest killing device in the above embodiment 1. The method comprises the following steps: Step 1: Preset the target temperature value T of the mixed gas formed by mixing dry ice and nitrogen to 10°C; Step 2: Calculate the mass ratio of dry ice to nitrogen (m2 / m1) based on the target temperature. The specific calculation formula is as follows: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)]=1.040×(25-10) / [335+0.846×(78.5+0)]≈1:26; Wherein, C1 is the specific heat capacity of nitrogen = 1.040 J / g·°C, T1 is the temperature of nitrogen (in this embodiment, the nitrogen temperature is room temperature 25°C), γ is the latent heat of vaporization of dry ice = 335 kJ / kg, and C2 is the specific heat capacity of dry ice particles = 0.846 J / (g·°C); Step 3: Open the temperature control valve 3 to control the feed speed and time of dry ice and the intake flow rate of nitrogen. Dry ice is added to the dry ice feeder 6 in the form of dry ice pellets, and the dry ice and nitrogen are simultaneously introduced into the mixing insulation chamber 5. The dry ice and nitrogen are mixed in a mass ratio of 1:26. The feed amount of dry ice and the intake amount of nitrogen are then appropriately adjusted in real time according to the temperature detected by the temperature detector on the intake pipe 7 to form a mixed gas with a temperature of 10±0.2°C. The mixed gas then enters the sealed tent; Step 4: The temperature sensor 11 detects the temperature in the sealed warehouse in real time, the gas detector 13 detects the gas composition and concentration in real time, and the PLC controller 8 adjusts the electromagnetic control valves on the air inlet pipe 7 and the exhaust pipe 12 according to the corresponding detection values, so that the oxygen concentration in the sealed tent is ≤2% and maintained for more than 15 days (including 15 days).

[0038] In this example, the sealed warehouse had a storage capacity of 3,500 m³, and the ventilation time was 66 hours, with the mixed atmosphere being introduced to a conditioned oxygen concentration of ≤2% within the sealed warehouse. After maintaining this hypoxic (oxygen concentration ≤2%) environment for 15 days (inclusive), the mortality rate of tobacco pests within the sealed warehouse reached 100%. No pests were detected within the warehouse for nine months after the controlled atmosphere was established.

[0039] Example 3 The low-temperature controlled atmosphere pest control method of this embodiment is substantially the same as that of Example 2, except that: In step 1, the preset target temperature value T=5°C; In step 2, the masses of dry ice and nitrogen are: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)]=1.040×(25-4) / [335+0.846×(78.5+0)]≈1:20; In step 3, a mixed gas with a temperature of 5±0.2°C is formed by using dry ice and nitrogen in a mass ratio of 1:20; In step 4, the oxygen concentration in the sealed tent is maintained at ≤ 2% for more than 8 days.

[0040] In this example, the sealed warehouse had a storage capacity of 3,500 cubic meters, and the mixed atmosphere was filled with controlled atmosphere gas until the oxygen concentration within the sealed warehouse reached ≤2% over a 60-hour ventilation period. Using this low-temperature controlled atmosphere pest control method, the mortality rate of tobacco pests within the sealed warehouse reached 100%, and no pests were detected within the warehouse for nine months after the controlled atmosphere treatment.

[0041] Comparative Example 1 In this embodiment, referring to the method of the "Temperature-controlled Nitrogen-Filled Controlled Atmosphere Insecticide Application Test", a 98% nitrogen concentration (room temperature 25°C) was filled into a 3500 m³ sealed warehouse. The gas in the sealed warehouse was replaced to a low oxygen environment of ≤2% for 120 hours. After the low oxygen environment was maintained for 40 days, the insecticide rate reached 100%. No pests were detected in the warehouse for 9 months after the controlled atmosphere.

[0042] Comparative Example 2 The method control example was completed with reference to the method of a device and method for controlling pests using carbon dioxide disclosed in Chinese patent No. CN104957127B, that is, a carbon dioxide concentration of ≥95% (room temperature 25°C) was filled into a warehouse space of 3500m³ in a sealed warehouse, and the ventilation time was 80 hours until the carbon dioxide concentration in the sealed tent reached 55-60% and the oxygen concentration was ≤2%. After maintaining the low oxygen environment for 8 days, the insecticide rate reached 100%, and no pests were detected in the warehouse for 9 months after the atmosphere was controlled.

[0043] Comparative Example 3 With reference to Example 5 of a device and method for controlling pests using carbon dioxide disclosed in Chinese patent number CN104957127B, the method is completed, that is, a sealed warehouse with a warehouse space of 3500m³ is filled with carbon dioxide with a concentration of ≥95%, and the carbon dioxide concentration in the sealed tent reaches 60% and the oxygen concentration is ≤2%, the temperature is 30°C, the ventilation time is 72.5 hours, and after the low oxygen environment is maintained for 2 days, the insecticide rate reaches 100%, and no pests are detected in the warehouse for 9 months after the atmosphere is adjusted.

[0044] Example 4 The low-temperature controlled atmosphere pest control method of this embodiment is substantially the same as that of Example 2, except that: In step 1, the preset target temperature value T=4°C; In step 2, the mass ratio of dry ice to nitrogen is: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)]=1.040×(25-4) / [335+0.846×(78.5+0)]≈1:18.5; In step 3, a mixed gas with a temperature of 4±0.2°C is formed by using dry ice and nitrogen in a mass ratio of 1:18.5; In step 4, the oxygen concentration in the sealed tent is maintained at ≤ 2% for more than 6 days.

[0045] In this embodiment, the low-temperature controlled atmosphere pest control method was used in a sealed warehouse with a storage space of 3500 m³. The mixture was filled with controlled atmosphere gas until the oxygen concentration in the sealed warehouse reached ≤2%, and the ventilation time was 58.8 hours. Using this low-temperature controlled atmosphere pest control method, the mortality rate of tobacco pests in the sealed warehouse reached 100%, and no pests were detected in the warehouse for 9 months after the controlled atmosphere treatment.

[0046] Example 5 The low-temperature controlled atmosphere pest control method of this embodiment is substantially the same as that of Example 2, except that: In step 1, the preset target temperature value T=2°C; In step 2, the mass ratio of dry ice to nitrogen is: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)]=1.040×(25-2) / [335+0.846×(78.5+0)]≈1:17; In step 3, a mixed gas with a temperature of 2±0.2°C is formed by using dry ice and nitrogen in a mass ratio of 1:17; In step 4, the oxygen concentration in the sealed tent is maintained at ≤ 2% for more than 4.5 days.

[0047] In this embodiment, the low-temperature controlled atmosphere pest control method was used in a sealed warehouse with a storage space of 3500 m³. The mixture was filled with controlled atmosphere gas until the oxygen concentration in the sealed warehouse reached ≤2%, and the ventilation time was 54.5 hours. Using this low-temperature controlled atmosphere pest control method, the mortality rate of tobacco pests in the sealed warehouse reached 100%, and no pests were detected in the warehouse for 9 months after the controlled atmosphere treatment.

[0048] Example 6 The low-temperature controlled atmosphere pest control method of this embodiment is substantially the same as that of Example 2, except that: In step 1, the preset target temperature value T=0°C; In step 2, the mass ratio of dry ice to nitrogen is: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)]=1.040×(25-0) / [335+0.846×(78.5+0)]≈1:15; In step 3, a mixed gas with a temperature of 0±0.2°C is formed by using dry ice and nitrogen in a mass ratio of 1:15; In step 4, the oxygen concentration in the sealed tent is maintained at ≤ 2% for more than 3 days.

[0049] In this embodiment, the low-temperature controlled atmosphere pest control method involves a sealed warehouse with a storage space of 3500 m³. The warehouse is filled with a mixed controlled atmosphere gas until the oxygen concentration in the sealed warehouse reaches ≤2%, and the ventilation time is 49.5 hours. Using this low-temperature controlled atmosphere pest control method, the tobacco pest mortality rate in the sealed warehouse reached 100%, and no pests were detected in the warehouse for 9 months after the controlled atmosphere treatment.

[0050] Example 7 The low-temperature controlled atmosphere pest control method of this embodiment is substantially the same as that of Example 2, except that: In step 1, the preset target temperature value T=-5°C; In step 2, the room temperature of nitrogen is 20°C, and the mass ratio of dry ice to nitrogen is: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)]=1.040×(20-(-5)) / [335+0.846×(78.5+0)]≈1:15; In step 3, a mixed gas with a temperature of -5±0.2°C is formed by using dry ice and nitrogen in a mass ratio of 1:15; In step 4, the oxygen concentration in the sealed tent is maintained at ≤ 2% for more than 2 days.

[0051] In this embodiment, the low-temperature controlled atmosphere pest control method involves a sealed warehouse with a storage space of 3500 m³. A mixed controlled atmosphere gas is introduced until the oxygen concentration in the sealed warehouse reaches ≤2%, and the ventilation period is 48 hours. Using this low-temperature controlled atmosphere pest control method, tobacco pest mortality in the sealed warehouse reached 100%, and no pests were detected in the warehouse nine months after the controlled atmosphere treatment.

[0052] Results and Analysis It should be noted that when the temperature of the mixed gas conditioning gas to be regulated remains unchanged (e.g., 0°C or 5°C), the lower the room temperature in the sealed warehouse, that is, the lower the temperature of the input nitrogen, the less heat is required to cool the nitrogen, and the lower the mass of dry ice required to be added. However, in order to make the density of the mixed gas conditioning gas greater than the density of the residual air in the sealed warehouse (at room temperature), that is, the increase in the density of the nitrogen is greater than 0.04 kg / m3, the temperature of the nitrogen must drop by at least 10°C (the temperature change range is estimated by referring to the density of nitrogen at different temperatures at 0.1 MPa). Therefore, a mass ratio of dry ice to nitrogen between 1:15 and 1:40 can meet the heat exchange requirements for cooling nitrogen at room temperature between 10-30°C to below 10°C, with a temperature drop of more than 10°C.

[0053] Controlled atmosphere pest control was performed in sealed warehouses (storing tobacco leaves) of the same volume (3500 m³) according to Examples 2-7 and Control Examples 1-3. Concurrently, tobacco beetle eggs, 2nd-3rd instar larvae, and adults approximately one week after eclosion, whose development and vitality were similar, were placed in different warehouses. During the treatment, the cages were removed every 12 hours and placed in a constant temperature incubator at (30±1)°C and 70% relative humidity for 7 days. After 7 days, adult survival, larval eclosion, and egg hatching were recorded. Larvae that failed to eclosion normally, eggs that failed to hatch normally, and non-surviving adults were recorded as dead. Mortality was calculated, and the hypoxia treatment time required to achieve 100% mortality for tobacco beetle adults, larvae, and eggs was determined.

[0054] Table 1 shows the ventilation time required for different controlled atmosphere insecticide methods to create a low-oxygen environment and the treatment time required to maintain a low-oxygen environment to achieve 100% mortality of tobacco beetle eggs. The experimental results of Comparative Examples 1-3 show that compared to the controlled atmosphere insecticide method using only nitrogen (at room temperature), the carbon dioxide-filled controlled atmosphere method achieved a shorter insecticide time. Furthermore, the time required to maintain a low-oxygen environment for tobacco leaf insecticide using heated carbon dioxide gas was further reduced compared to that required using room-temperature carbon dioxide gas. Compared to Comparative Example 2, Examples 3-7 used dry ice to cool nitrogen to form a mixed controlled atmosphere gas, which then replaced the atmosphere in the sealed warehouse to create a low-oxygen environment. The low-temperature mixed controlled atmosphere gas shortened the ventilation time for the low-oxygen environment, and the treatment time required to maintain the low-oxygen environment was also less than or equal to that in Comparative Example 2. However, Comparative Example 2 required the use of a high concentration of carbon dioxide (55-60%), which consumes more energy. Therefore, the methods of Examples 3-7 also reduced energy consumption compared to Comparative Example 2. In Comparative Example 3, the treatment time required to maintain the hypoxic environment was shortened by heating the high-concentration (60%) carbon dioxide gas. However, the injection of the heated high-concentration carbon dioxide itself consumes a large amount of energy. The methods of Examples 2-7 shortened the hypoxic ventilation time and eliminated the need for a heated gas heater, greatly reducing the energy consumption and operating costs during the hypoxic environment ventilation cycle.

[0055] Compared to creating a low-oxygen environment by filling a sealed warehouse with room-temperature nitrogen, the present invention uses a low-temperature mixed gas to achieve a low-oxygen environment. This significantly shortens the ventilation time required to achieve the low-oxygen environment, with the shortest ventilation time being reduced to 48 hours. Compared to room-temperature nitrogen and room-temperature carbon dioxide controlled atmosphere pest control methods, the present invention's mixed gas controlled atmosphere pest control method, formed by low-temperature nitrogen and carbon dioxide, achieves the same insecticidal effect (e.g., achieving 100% mortality for tobacco pests such as tobacco beetles) with significantly shorter ventilation times and the time required to maintain the low-oxygen environment, demonstrating the significant synergistic effect of low temperature, carbon dioxide, and nitrogen in controlled atmosphere pest control.

[0056]

[0057] Example 8 Reference Figure 4 The low-temperature controlled atmosphere insecticide device of this embodiment has the following differences compared with Example 1: The air inlet pipe 7 and the air outlet pipe 12 are respectively installed on two opposite sides of the middle of the sealed warehouse, which is convenient for assembly and disassembly of the sealed warehouse.

[0058] Example 9 Reference Figure 5 The low-temperature controlled atmosphere insecticide device of this embodiment has the following differences compared with Example 1: The output end of the exhaust pipe 12 is connected to the exhaust device 17, and the low-temperature mixed gas enters through the intake pipe 7, quickly accumulates at the bottom of the stereoscopic warehouse and replaces the residual air inside, thereby shortening the ventilation time required for the low-oxygen environment.

[0059] The sealed warehouse of this embodiment is a tobacco storage stereoscopic warehouse 16, and its structure is the same as the storage stereoscopic warehouse 16 disclosed in Chinese patent CN217986468U, a gas transmission device for nitrogen fumigation of a comprehensive tobacco storage stereoscopic warehouse. The storage stereoscopic warehouse 16 consists of several columns, and a plurality of parallel and spaced tracks 1601 for moving cigarette stack trays are provided between adjacent columns.

[0060] In this embodiment, a low-temperature controlled atmosphere insecticide device replaces the sealed tent with a bottom film 14 in Example 1 with a tent without a bottom film 14. The tent without a bottom film 14 is manufactured by referring to the method for manufacturing a sealed tent in a storage device without a bottom film 14 disclosed in Chinese patent CN 104322479 A. The changes in the above technical features can be understood and implemented by those skilled in the art through textual descriptions, so they are not further illustrated.

[0061] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-temperature controlled atmosphere insecticide device, characterized in that: The invention comprises a nitrogen generator, a mixing insulation chamber and a sealed warehouse which are sequentially connected along the air inlet direction, wherein the mixing insulation chamber is connected to a dry ice feeder, and a discharge end of the dry ice feeder and an air outlet end of the nitrogen generator are respectively provided with temperature control valves, and the feed amount of dry ice and the air intake amount of nitrogen are controlled by the temperature control valves, and a mixed gas of dry ice and nitrogen is formed in the mixing insulation chamber and introduced into the sealed warehouse.

2. The low-temperature controlled atmosphere insecticide device according to claim 1, characterized in that: The nitrogen generator is connected to the mixing insulation chamber through a connecting pipe, the mixing insulation chamber is connected to the sealed warehouse through an air inlet pipe, and the air outlet end of the sealed warehouse is connected to the nitrogen generator through an exhaust pipe; The temperature control valve is arranged on the connecting pipe, and the air intake pipe and the exhaust pipe are both provided with an electromagnetic control valve and a one-way check valve; the air intake pipe is also provided with a temperature detector.

3. The low-temperature controlled atmosphere insecticide device according to claim 1, characterized in that: The sealed warehouse is provided with a temperature sensor and a gas detector.

4. The low-temperature controlled atmosphere insecticide device according to claim 1, characterized in that: The discharge end of the dry ice feeder extends to the interior of the mixing insulation chamber and is provided with a filter screen at its end, and the bottom surface of the filter screen protrudes downward in a semi-rugby shape.

5. The low-temperature controlled atmosphere insecticide device according to claim 2, characterized in that: The output end of the air inlet pipe is installed at the bottom of the sealed warehouse, and the input end of the exhaust pipe is installed at the top of the sealed warehouse.

6. The low-temperature controlled atmosphere insecticide device according to claim 1, characterized in that: The dry ice feeder comprises a heat-insulating sealing cylinder, a sealing cover is provided on the top of the heat-insulating sealing cylinder, a sealing valve plate is provided in the middle of the heat-insulating sealing cylinder, the sealing valve plate divides the inner cavity of the heat-insulating sealing cylinder into a feeding cavity and a discharging cavity, a rotating shaft is transmission-connected in the middle of the sealing valve plate, one end of the rotating shaft extends to the outside of the heat-insulating sealing cylinder and is provided with an operating handle, and the bottom end of the discharging cavity is connected to the mixing insulation chamber.

7. The low-temperature controlled atmosphere insecticide device according to claim 6, characterized in that: The heat-insulating sealing cylinder comprises an inner cylinder body, and the outer wall surface of the inner cylinder body is sequentially wrapped with a heat-insulating layer and an outer shell provided with a vacuum interlayer.

8. A method for killing insects by low-temperature controlled atmosphere, the method being applied to the low-temperature controlled atmosphere pest killing device according to any one of claims 1 to 7, characterized in that: The nitrogen is cooled by dry ice, so that the mixed gas formed by dry ice and nitrogen enters the sealed warehouse. The introduced mixed gas reduces the oxygen concentration in the sealed warehouse to ≤2% and maintains the low oxygen environment for less than 15 days; the temperature of the mixed gas is lower than 10°C.

9. The method of low-temperature controlled atmosphere pest control according to claim 8, characterized in that: The following steps are involved: Step 1: preset a target temperature value T of the mixed gas formed by dry ice and nitrogen; wherein the target temperature value is ≤5°C; Step 2: Obtain the mass ratio of the dry ice and nitrogen mixture according to the target temperature value T; Step 3: A mixed gas is formed according to the mass ratio of dry ice and nitrogen, the nitrogen is cooled with dry ice, and the mixed gas is properly regulated so that the gas reaches the preset target temperature value before entering the sealed warehouse; Step 4: The introduced mixed gas will reduce the oxygen concentration in the sealed warehouse to ≤2% and maintain the low oxygen environment for less than 8 days.

10. The low-temperature controlled atmosphere insecticide method according to claim 9, characterized in that: In step 2, the mass ratio of dry ice to nitrogen is calculated as follows: m2 / m1=C1×(T1-T) / [γ+C2×(78.5+T)] Wherein, C1 is the specific heat capacity of nitrogen, T1 is the temperature of nitrogen, γ is the latent heat of vaporization of dry ice, and C2 is the specific heat capacity of dry ice particles.

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