"Fumigation apparatus and fumigation method"

Abstract

According to one example of the present disclosure, a fumigation apparatus comprises a mixing chamber having a first inlet and a second inlet. A gas regulator, pump, or compressor directs the flow of non-combustible gas along a first channel, from a non-combustible gas source, through or via a heater, to the first inlet of the mixing chamber, and a chemical agent pump directs the flow of chemical fumigant along a second channel, from a chemical fumigant supply source, to the second inlet of the mixing chamber. A temperature sensor measures the temperature of the mixed flow of hot gas and chemical fumigant at the outlet of the apparatus. A controller controls the gas regulator, pump, or compressor and / or chemical agent pump based on the temperature measured by the temperature sensor to maintain the flow of hot gas and chemical fumigant exiting the fumigation apparatus outlet at a predetermined temperature or higher.

Description

Technical Field

[0001] The present disclosure relates to a fumigation device and a fumigation method.

Background Art

[0002] Fumigants are typically volatile chemical substances or toxic gases generated from liquid and / or solid agents. They have bactericidal, fungicidal, insecticidal and / or nematicidal properties and are used to disinfect, kill and control pests, pathogens and weeds. Fumigation is a technique for distributing and applying gaseous substances into an enclosure for the purpose of disinfecting, controlling or eliminating particularly undesirable organisms.

[0003] Fumigants are active in the gaseous state and can penetrate into crops and the free airspace around them, as well as into cracks and gaps in storage structures and enclosures, at toxic concentrations, and kill target organisms and their reproductive stages. Fumigants are generally not only effective but also relatively inexpensive, and thus are widely used for the control or killing of stored products, food, cut flowers, wood, buildings, soil insects, rodents, and fungi.

[0004] Foods such as fruits and grains are particularly vulnerable to invertebrate invasion. Some economic regions such as Australia have a policy of "not allowing any live insects" in exports in order to protect the reputation of local agricultural products. These regions usually adopt extensive fumigation practices to reduce the risk of infection. Pests can also occur in equipment and facilities, and can be treated by fumigation to control these pests. Similarly, buildings, ships, containers, fruit trees, wood and soil may require treatment by fumigation to control various pathogens and pests.

[0005] There are numerous chemical agents that can be used as fumigants for fumigation purposes, including hydrogen cyanide, calcium cyanide, carbon dioxide, sulfur dioxide, carbon tetrachloride, ethylene dichloride, ethyl formate, ethylene bromide, p-dichlorobenzene, 1,3-dichloropropane, chloropicrin, formaldehyde, methyl isocyanate, phosphine, methyl bromide, and sulfuryl fluoride. Each of these agents has specific advantages and disadvantages, including hazards from toxicity and flammability.

[0006] Methyl bromide and phosphine are two chemical agents commonly used to control or prevent the spread of invertebrate disease through fumigation. Methyl bromide is a broad-spectrum pesticide with nonspecific toxicity to a wide range of invertebrates. However, exposure to high concentrations of methyl bromide can have harmful effects on humans and other animals. Methyl bromide has a further drawback in that it is widely accepted to be a known and significant ozone-depleting substance. Artificial addition of methyl bromide to the atmosphere via fumigation thins the ozone layer, and its harmful effects are well known and documented. Nevertheless, methyl bromide remains a preferred fumigant for many quarantine authorities.

[0007] Phosphine is often relied upon for fumigation of grains and other similar commodities, and is effective when used appropriately. However, due to improper application and over-reliance, reports of phosphine resistance are increasing. Some regions that rely almost entirely on this single fumigant throughout the value chain are at risk of developing phosphine resistance and require the implementation of phosphine resistance monitoring and control programs.

[0008] Ethyl formate is a chemical agent that exhibits usefulness as a fumigant, particularly in the control of invertebrates. Ethyl formate vapor has been shown to be toxic to common insects when used to infest stored goods. Ethyl formate is a naturally occurring compound found in various foods and rapidly decomposes into harmless naturally occurring compounds. Despite being absorbed into the body through inhalation and ingestion of its vapors, and through skin and / or eye contact, ethyl formate has relatively low human toxicity. These characteristics make it suitable for food processing.

[0009] Ethyl formate is a liquid at normal ambient temperatures and has a boiling point of 54°C, but is present in concentrations of 2.8% (v / v) or 92 g / m³. -3 It is highly flammable at its lower explosive limit (LEL). This poses a significant problem in the practical application of ethyl formate as a fumigant, as conditions that could ignite a flame must be avoided. Other fumigants useful for controlling invertebrates, such as ethylene chloride and propylene oxide, also have similar flammability concerns when used as fumigants.

[0010] Fumigation is inherently a dangerous operation because the chemicals used in fumigation are, in some cases, toxic to most forms of life, including humans. The use of flammable chemicals increases the level of hazard because, in order to apply liquid chemicals as fumigants, the chemicals must be converted from liquid to gas by a vaporizer, which typically requires some application of heat. Applying liquid chemicals without vaporization is undesirable because levels of non-vaporized chemicals can cause occupational health and safety concerns and / or damage to goods being treated with the chemicals.

[0011] Therefore, the application of flammable agents as fumigants requires careful handling to mitigate the risk of ignition. It is known that liquid agents and non-flammable gases are mixed in a cylinder to form a non-flammable formulation under high pressure. However, the practice of using gas in a cylinder has at least one drawback: the potential for carburetor freezing, especially in cold or humid environments. This effect can significantly increase the application time as the gas cylinder and regulator freeze. Furthermore, when using pressurized fumigants, well-trained fumigant operators who are properly trained in handling high-pressure cylinders must be employed to apply the fumigant.

[0012] It is also known that a fumigant that is substantially non-flammable under high pressure can be produced by combining a liquid fumigant with carbon dioxide. The carbon dioxide is provided in an amount sufficient to render the flammable liquid non-flammable. However, these mixtures have all the limitations associated with the use of pressurized canisters, as well as additional limitations such as undesirable degradation or corrosion of some materials by carbon dioxide, greenhouse gas emissions, and phytotoxicity to fresh fruits and vegetables. These difficulties limit the scope of use of such mixtures.

[0013] Existing vaporizer designs can exhibit variability in the heating of liquid chemicals, resulting in incomplete or partial vaporization of the chemical. This can lead to inefficient and ineffective application of the chemical, including non-uniform distribution of the chemical throughout the treatment area and / or damage to the material due to sedimentation of unvaporized chemical. Known vaporizer designs are also typically limited to a single batch or limited volume of liquid chemical in the chamber. The chamber must be refilled with liquid chemical before further application, typically requiring not only a shutdown but also a cooling period between applications. Therefore, there is a need for improvements in fumigation techniques, an expansion of the range of chemicals that can be used safely and effectively for fumigation, and a reduction in the inefficiencies and safety risks of various operations.

[0014] The considerations of documents, actions, materials, devices, articles, etc., contained herein shall not be deemed to acknowledge that any or all of these matters form part of the basis of the prior art or were common knowledge in the art relevant to this disclosure prior to the priority date of each claim of this application.

[0015] Throughout this specification, the term “comprise,” or variations such as “comprise” or “comprising,” shall be understood to mean including the elements, integers, or steps, or groups of elements, integers, or steps described herein, but not to exclude any other elements, integers, or steps, or groups of elements, integers, or steps. [Overview of the project]

[0016] With the foregoing in mind, according to a first aspect of the present disclosure, a fumigation apparatus comprising: a mixing chamber including a first inlet for receiving a flow of high-temperature gas, a second inlet for receiving a flow of chemical fumigant, and a mixing chamber outlet for outputting a mixed flow of high-temperature gas and chemical fumigant; a gas regulator, pump, or compressor for directing a flow of non-combustible gas along a first channel from a non-combustible gas source to the first inlet of the mixing chamber; a heater for heating the flow of non-combustible gas in the first channel to provide a flow of high-temperature gas to the first inlet of the mixing chamber; and a flow of chemical fumigant, A fumigation apparatus is provided, comprising: a chemical agent pump for directing a chemical fumigant from a supply source to a second inlet of a mixing chamber along two channels; a fumigation apparatus outlet in fluid communication with the mixing chamber outlet for discharging a mixed flow of high-temperature gas and chemical fumigant; a temperature sensor for measuring the temperature of the mixed flow of gas and chemical fumigant exiting the fumigation apparatus outlet; and a controller for controlling a gas regulator, pump or compressor and / or chemical agent pump based on the temperature measured by the temperature sensor to maintain the flow of high-temperature gas and chemical fumigant exiting the fumigation apparatus outlet at or above a predetermined temperature.

[0017] The apparatus may also include a gas flow meter for measuring the flow rate of the gas flow in the first channel, and the controller is configured to control a gas regulator, pump or compressor, and / or chemical agent pump at least in part based on the flow rate measured by the gas flow meter.

[0018] The controller can implement a negative feedback loop to control the gas regulator, pump, or compressor, dynamically adjusting the gas flow rate through the first channel to maintain the output temperature of the mixed flow of high-temperature gas and chemical fumigant above a predetermined temperature. The controller is configured to control the gas regulator, pump, or compressor based on the temperature measured by a temperature sensor, while the chemical agent pump operates independently of the temperature measured by the temperature sensor and / or the gas flow rate measured by the gas flow meter. The temperature of the flow of high-temperature gas and chemical fumigant exiting the fumigation device outlet may be lower than the heater temperature.

[0019] In some examples, the controller is configured to control a gas regulator, pump, or compressor so that for every 3 liters of chemical fumigant pumped through a second channel by a chemical agent pump, 4,500 to 6,000 liters of gas flow through the first channel.

[0020] In some examples, the second inlet of the mixing chamber is equipped with a nozzle for spraying the liquid chemical agent entering the mixing chamber. The nozzle may be a hydraulic spray nozzle.

[0021] In some examples, the first inlet of the mixing chamber is located at the first end of the mixing chamber, and the second inlet is located at the second end opposite the first end of the mixing chamber, so that the high-temperature gas flow and the chemical agent flow enter the mixing chamber from opposite directions to generate turbulence. The outlet of the mixing chamber may be located on the side wall joining the first and second ends of the mixing chamber, so that the mixed flow of high-temperature gas and chemical fumigant exits the mixing chamber through the outlet in a direction substantially perpendicular to the direction in which the high-temperature gas flow and the chemical agent flow enter the mixing chamber.

[0022] In some examples, the fumigation apparatus comprises a vaporization coil having a first end that is in fluid communication with the outlet of a mixing chamber and a second end that forms the outlet of the fumigation apparatus or is in fluid communication with the outlet of the fumigation apparatus.

[0023] In some examples, the fumigation system includes a third channel which serves as a purge line, the third channel being in fluid communication with a gas source and joined to a second channel upstream of the mixing chamber, the third channel having a valve that, when open, allows a gas flow to pass through the third channel to the second channel and purge the chemicals in the second channel. A chemical pump may be located downstream of the point where the third channel joins the second channel, so that the chemical pump can be purged.

[0024] In some examples, the controller, gas regulator and pump, as well as the gas flow meter, are housed within a housing configured to provide an oxygen-reduced environment. Part of the first channel passing through the housing may include a purge vent for injecting gas from a gas source into the housing to release oxygen from the housing. An oxygen sensor may be located inside the housing, and the controller is configured to turn off a heater in response to the oxygen sensor detecting oxygen in the housing.

[0025] In some examples, the heater is positioned above the mixing chamber. The second channel may include a corrosion-resistant material. At least a portion of the first channel extending from the heater to the mixing chamber may include a heat-resistant material. The vaporization coil may be heat-resistant and corrosion-resistant. A portion of the first channel extending from the second channel and the regulator to the heater may be formed of a flexible material. The flexible material of the second channel may be coated with a corrosion-resistant material.

[0026] In some examples, the chemical fumigant is ethyl formate. In some examples, the non-combustible gas is an inert gas. The gas source may be external to the fumigation device. The chemical agent source may be external to the fumigation device.

[0027] In some examples, the fumigation device includes a second temperature sensor for measuring the temperature of the hot gas in the first channel near the heater and transmitting information regarding the measured temperature to a controller, and the controller is configured to control the heater.

[0028] According to a second aspect of the present disclosure, a fumigation device includes a mixing chamber including a first inlet for receiving a flow of hot gas, a second inlet for receiving a flow of chemical fumigant, and a mixing chamber outlet for outputting a mixed flow of hot gas and chemical fumigant, a gas regulator / pump / compressor for directing a flow of non-combustible gas along a first channel from a non-combustible gas source to the first inlet of the mixing chamber, a heater for heating the gas flow in the first channel of the mixing chamber to provide a flow of hot gas to the first inlet of the mixing chamber, a chemical agent pump for directing a flow of chemical fumigant along a second channel from a supply source of chemical fumigant to the second inlet of the mixing chamber, and a fumigation device outlet in fluid communication with the mixing chamber outlet for discharging the mixed flow of hot gas and chemical fumigant, wherein the first inlet of the mixing chamber is at a first end of the mixing chamber and the second inlet of the mixing chamber is at a second end opposite the first end of the mixing chamber, so that the hot gas flow and the chemical agent flow enter the mixing chamber from opposite directions to generate a turbulent flow.

[0029] According to a third aspect of the present disclosure, a fumigation method using the fumigation device of the first aspect or the second aspect is provided. The method includes flowing an inert gas through a first channel to a heater to heat the inert gas and enabling the heated inert gas to enter a mixing chamber, pumping a liquid fumigant through a second channel to the mixing chamber, mixing the liquid fumigant and the heated inert gas in the mixing chamber to form a fumigant including a mixture of a high-temperature gas and a vaporized fumigant in the mixing chamber, enabling the flow of the fumigant to exit the mixing chamber, and directing the fumigant from an outlet of the fumigation device to a region to be fumigated.

[0030] In some examples, the inert gas is selected from the group including nitrogen, helium, and carbon dioxide. In some examples, the liquid fumigant is ethyl formate.

Brief Description of the Drawings

[0031] To more easily understand the present disclosure, embodiments will be described by way of example with reference to the accompanying drawings.

[0032] [Figure 1] A perspective view of a fumigation device according to an example of the present disclosure. [Figure 2] A perspective view of the fumigation device of FIG. 1 with the housing partially removed so that internal components can be seen. [Figure 3] A side view of the fumigation device of FIG. 2 showing a heater and a mixing chamber. [Figure 4] A schematic diagram of components of a fumigation device according to an example of the present disclosure. [Figure 5] A flowchart showing a method for controlling an output temperature by a controller of a fumigation device according to an example of the present disclosure. [Figure 6] A further flowchart showing a method for controlling an output temperature by a controller of a fumigation device according to an example of the present disclosure. [Figure 7]This is a schematic diagram illustrating the operation of a controller for controlling the output fumigant temperature according to the example of the present disclosure. [Figure 8] This is a schematic diagram illustrating a control loop for controlling a heater, as shown in this disclosure. [Modes for carrying out the invention]

[0033] Referring first to Figures 1-4, an example of a fumigation apparatus 100 used to vaporize a chemical fumigant, typically a liquid chemical, for application as a fumigant. A fumigant is a gaseous substance used to kill insects, nematodes, and other animals or plants that damage stored food or seeds. A chemical fumigant is a chemical that can be vaporized to form a fumigant.

[0034] The fumigation apparatus 100 has a particular utility for vaporizing chemical agents having properties such as flammability; otherwise, it would make the chemical agent unsuitable or undesirable for use as a fumigant. However, the vaporizer 100 can be used to vaporize any chemical agent desired for use as a fumigant, including but not limited to ethyl formate, methyl bromide, 1,3-dichloropropane, chloropicrin, and propylene oxide. The fumigation apparatus vaporizes the chemical agent by mixing a flow of high-temperature gas with a flow of liquid chemical agent to vaporize the chemical agent. Because certain chemical agents, such as ethyl formate, are highly flammable, the apparatus uses a non-flammable gas to heat the chemical agent. The non-flammable gas may be, for example, an inert gas such as nitrogen, helium, or carbon dioxide.

[0035] The temperature of the fumigant, which includes a mixture of high-temperature gas and vaporized chemicals, should preferably be kept above the boiling point of the chemicals when it leaves the device. Otherwise, the chemicals may condense prematurely, leading to incomplete or ineffective fumigation. When a flow of high-temperature gas mixes with a flow of chemicals, the temperature of the mixture is determined in part by the temperature and flow rate of the high-temperature gas flow. The flow rate of the high-temperature gas flow is particularly important because a higher gas flow rate results in a higher temperature of the fumigant discharged from the device. Therefore, a first aspect of this disclosure proposes measuring the temperature of the fumigant exiting the fumigation apparatus and dynamically controlling the flow rate of the gas flow based on the measured temperature to maintain the flow of fumigant exiting the apparatus above a predetermined temperature.

[0036] Several previous designs of fumigation systems have been found to result in incomplete mixing and vaporization of chemicals by high-temperature gas, potentially leading to suboptimal fumigation. Therefore, a second aspect of this disclosure proposes a mixing chamber in which a high-temperature gas flow enters through an inlet at a first end of the mixing chamber, and a chemical flow enters through an inlet at a second end of the mixing chamber opposite the first end. The entry of the high-temperature gas flow and chemical flow into the mixing chamber in opposite directions promotes turbulence and more complete mixing and vaporization of the chemicals.

[0037] In some examples, the components of the fumigation apparatus may be held or otherwise housed within a housing 102. The housing 102 may comprise a frame and a cover. An example is shown in Figure 1. The housing 102 may comprise a polymer case. Preferably, the polymer case may be portable, lightweight, and resistant to water, pulverization, and dust. For example, the case may be a Pelican® style case. The case may be formed from copolymerized polypropylene using an open-cell core and solid-wall structure.

[0038] The fumigation apparatus 100 may be portable. For example, the fumigation apparatus 100 may be presented as a substantially small and mobile unit. Portability allows a single operator to easily move the apparatus 100 from one treatment site to another. The morphable nature and small size of the fumigation apparatus 100 allow for use in small areas such as small grain silos, as well as in larger areas such as warehouses, buildings, and ship holds.

[0039] Referring to Figure 1, the fumigation apparatus 100 may include a first inlet 1 for receiving a flow of non-combustible gas, a second inlet 2 for receiving a flow of liquid chemical agent, and an outlet 3 for discharging the fumigant containing a mixture of high-temperature gas and vaporized chemical agent. In the example shown in Figure 1, the first inlet 1 for non-combustible gas is located next to the second inlet 2 for liquid chemical agent. The fumigation apparatus may also include a control panel 4, which may take the form of a display and be connected to a controller for controlling the operation of the fumigation apparatus. For example, the control panel 4 may be used to start and stop the inflow of chemical agent and non-combustible gas into the apparatus, and to display and / or set the temperature and flow rate. The casing may include a lid 5, which may be hinged. The fumigation apparatus may have a power inlet 101 for receiving power.

[0040] The first inlet 1 can be fluidly connected to an external source of non-flammable gas 11, such as a gas cylinder or gas generator, by the use of a flexible tube or hose. The second inlet 2 can be fluidly connected to an external source of chemical agent 13, such as a container of liquid chemical agent, by the use of a flexible tube or hose.

[0041] Referring to Figure 4, the fumigation apparatus 100 comprises a first channel 10 leading from a first inlet 1 of the apparatus to a mixing chamber 60, and a second channel 20 leading from a second inlet 2 of the apparatus to the mixing chamber 60. During use, the mixing chamber 60 is used to mix a heated flow of non-combustible gas with a liquid flow of chemical fumigant, and the fumigant containing the mixed flow of the hot gas and vaporized chemical fumigant is output from the outlet 66 of the mixing chamber.

[0042] The fumigation apparatus includes a gas regulator 12 for directing the flow of non-combustible gas along a first channel 10 from a non-combustible gas source 11 to a first inlet 62 of a mixing chamber 60. In some examples, a pump or compressor may be used instead of a gas regulator, but a gas regulator is less expensive and is more easily controlled by the apparatus's controller 40. In most cases, even if there is a pump or compressor (either inside or outside the apparatus) to cause the gas flow through the first channel 10, a gas regulator is still present to better control the pressure and flow of gas in the first channel. The gas regulator, pump, or compressor is controlled by the controller 40.

[0043] The apparatus 100 further comprises a chemical agent pump 22 for directing the flow of chemical fumigant along the second channel 20 from the source of chemical fumigant 13 to the second inlet 64 of the mixing chamber 64. The apparatus also comprises a heater 50 for heating the flow of non-combustible gas in the first channel 10 in order to provide a flow of high-temperature gas to the first inlet 62 of the mixing chamber 60.

[0044] As mentioned above, the mixing chamber 60 includes a first inlet 62 ("high-temperature gas inlet") for receiving a flow of high-temperature gas, a second inlet 64 ("chemical agent inlet") for receiving a flow of chemical fumigant, and a mixing chamber outlet 66 for outputting a mixed flow of high-temperature gas and chemical fumigant. The fumigation device outlet 3 is in fluid communication with the mixing chamber outlet 66 and, during use, discharges a mixed flow of high-temperature gas and chemical fumigant ("fumigant") from the device. Thus, the fumigation device outlet 3 directs the fumigant into the surrounding atmosphere. The outlet 3 may have an opening of sufficient size to push the chemical agent / gas mixture outward, toward and into the area being treated, and to maintain a pressure sufficient to minimize condensation of the chemical agent.

[0045] An insulated delivery tube, such as a hose (not shown), may be connected to the fumigation apparatus outlet 3 to help direct the fumigant towards the area to be fumigated. The delivery tube should be long enough to deliver the chemical agent / gas to the treatment area, but should also be short enough and of an appropriate diameter to avoid significant cooling and condensation of the vapor as it moves from outlet 3 to the treatment area.

[0046] In some examples, a vaporization coil 70 may be located between the outlet 66 of the mixing chamber 60 and the outlet 3 of the fumigation device. The vaporization coil is a hollow coil tube. The vaporization coil may have a first end that is in fluid communication with the outlet 66 of the mixing chamber and a second end that forms the outlet 3 of the fumigation device or is in fluid communication with the outlet 3 of the fumigation device. The mixing chamber 60 may be relatively small, for example, the size of a cigarette pack, such as 80 to 12 cubic centimeters. The vaporization coil may be relatively long, for example, 2 to 6 meters in length. The diameter of the vaporization coil may be, for example, 8 mm to 20 mm. In one example, the vaporization coil is 3.5 m long and 12 mm in diameter. The vaporization coil 70 allows the chemical fumigant to completely vaporize and mix with the flow of hot gas before being discharged from the fumigation device. Because the vaporization coil 70 is in the shape of a coil, it is relatively small despite its length, which allows it to be fitted inside the housing of the fumigation apparatus, as best seen in Figures 2 and 3. For example, in one example, the coil is 3.5 m long but can be fitted into a space with an end-to-end length of 26 cm.

[0047] The apparatus may include a temperature sensor 72 for measuring the temperature of the mixed flow of gas and chemical fumigant exiting the fumigation apparatus outlet 3. The temperature sensor 72 may be located at or near the outlet 3. The apparatus includes a controller 40 for controlling the gas regulator, pump or compressor 12 and / or chemical agent pump based on the temperature measured by the temperature sensor 72 to maintain the flow of hot gas and chemical fumigant exiting the fumigation apparatus outlet at or above a predetermined temperature. The predetermined temperature may be above the boiling point of the chemical fumigant to be used. In the case of ethyl formate, the predetermined temperature is at least 54 degrees Celsius. In some examples, the predetermined temperature may be at least 5 degrees, at least 10 degrees, or at least 15 degrees Celsius higher than, for example, the boiling point of the chemical fumigant. This allows for some cooling as the mixture of hot gas and vaporized chemical agent comes into contact with the ambient air as it exits the fumigation apparatus. This contact with the ambient air can cause the fumigant to condense as it exits the apparatus, especially in winter. In some cases, the given temperature is 60 degrees Celsius or higher; in other cases, 65 degrees Celsius or higher; and in still other cases, 70 degrees Celsius or higher.

[0048] The controller 40 may be an electronic device such as a processor, microprocessor, programmable logic controller, field-programmable gate array, or integrated chip for a specific application. The controller may include a processor and machine-readable storage medium such as read-only memory, random-access memory, or solid-state memory for storing instructions executed by the processor to perform the control method described herein.

[0049] The controller may be configured to receive the temperature of the output fumigant from the temperature sensor 72 and automatically control the gas regulator, pump, or compressor 12 to dynamically adjust the flow rate of the gas in the first channel 10 to achieve a desired output temperature. The desired output temperature may be referred to as the predetermined output temperature. As mentioned above, the predetermined output temperature may be above the boiling point of the chemical fumigant, so that the chemical fumigant remains mostly vaporized and does not condense immediately upon leaving the device.

[0050] In some examples, the fumigation system may further include a gas flowmeter 19 for measuring the flow rate of the gas in a first channel 10, and the controller 40 may be configured to control a gas regulator, pump or compressor 12, and / or chemical agent pump 22, at least in part, based on the flow rate measured by the gas flowmeter 19. The gas flowmeter may be positioned in the first channel 10 upstream of the heater 50 so that the flow rate of the low-temperature or unheated gas is measured before it is heated.

[0051] In some examples, the controller 40 may be configured to use a negative feedback loop to control the gas regulator 12 and dynamically adjust the flow rate of gas through the first channel 10 so as to maintain the temperature of the mixed flow of hot gas and chemical fumigant at the outlet 3 of the fumigation device above a predetermined temperature. In some implementations, the controller 40 may control the flow rate via a gas pump or gas compressor instead of a gas regulator.

[0052] Figure 5 is a flowchart illustrating an exemplary control method 500 of a controller using a negative feedback loop. In block 510, the controller 40 receives the temperature of the fumigant exiting the device outlet 3 from the temperature sensor 72. In block 520, the controller determines whether the measured temperature is too low or too high compared to a desired target temperature ("predetermined temperature"). If the measured temperature is too low, in block 530, the controller 40 increases the gas flow rate in the first channel 10. If the measured temperature is too high, in block 540, the controller decreases the gas flow rate in the first channel 10.

[0053] The flow rate of high-temperature gas significantly affects the temperature of the fumigant output from the device, as faster flow rates result in greater heat transfer to the outlet. If the flow rate of high-temperature gas is too slow, the outlet temperature will fall below the desired temperature, and the chemical fumigant may not completely vaporize or may condense upon contact with the inside or outside air, leading to ineffective fumigation. Due to the high latent heat of vaporization, the gas passing through ethyl formate tends to cool rapidly, and in some cases, it may even freeze if the gas temperature or flow rate is too low. On the other hand, if the flow rate is too high, gas is wasted (costs are incurred because inert gas is not released), the device may overheat and be damaged, and the concentration of the chemical fumigant may fall below the effective fumigation level. Therefore, the controller is configured to automatically control the gas flow rate and dynamically adjust the device to achieve the desired flow rate when needed.

[0054] In other examples, the controller may not only regulate the gas flow rate but also, or instead, the heater temperature and / or the rate at which the chemical agent is pumped. However, generally, the rate at which the chemical agent is pumped is determined by the fumigation requirements. Typically, fumigation needs to be completed within a set time and requires a set volume of chemical fumigant (e.g., ethyl formate). The volume of fumigant required for a particular fumigation can be calculated based on the type of fumigant and the volume of the space being fumigated. Increasing the volume of fumigant would be expensive, as the fumigant is more expensive than the inert gas, and could exceed the toxicity limit. Decreasing the rate of fumigant increases the fumigation time, which is undesirable because fumigation usually needs to be completed within a set period for commercial considerations. Similarly, the heater is usually operated at the highest temperature to maximize the flow rate at which vaporization can occur, reducing the time it takes to vaporize the agent and deliver the fumigant. However, excessive increases in heater temperature can cause damage to the components of the equipment. For these reasons, in certain implementations, it is advantageous to control the output temperature of the fumigant by adjusting the gas flow rate rather than the heater temperature or the chemical pump flow rate.

[0055] Therefore, in some examples, the controller 40 may control the chemical agent pump 22 and / or heater independently of the temperature measured by the temperature sensor 72 and the gas flow rate measured by the gas flow meter 19. Thus, in some embodiments, the speed of the chemical agent pump 22 may be independent of the temperature of the output fumigant and the gas flow rate in the first channel 10.

[0056] The controller 40 can change the flow rate of gas through the first channel by adjusting the pressure of the main gas regulator 12. Increasing the pressure increases the flow rate, and decreasing the pressure decreases the flow rate. The flow rate at a given pressure depends on various factors, including the external environment from which the fumigant is discharged, such as the degree to which the container or area being fumigated is sealed, whether there are leaks in the container, the temperature, and other conditions, as well as the presence of back pressure from the external environment. As the fumigated area is filled with the fumigant, and if the container vent is blown open during fumigation or other events, the flow rate achieved at a given pressure can change not only by location but also during the fumigation process. For this reason, the required pressure will vary depending on the environmental conditions. Therefore, simply using the same pressure for all fumigation or having the user set the pressure and maintain a fixed pressure throughout the fumigation may not work well. Accordingly, the controller may employ a dual control loop with an outer loop targeting a desired output temperature for the fumigant and an inner loop targeting a flow rate to achieve the desired output temperature. In this way, the apparatus can explain the differences between different fumigation environments and the dynamic changes in conditions.

[0057] Figure 6 is a flowchart of a control method 600 implemented by the controller 40, in an example employing a dual control loop. In block 610, the controller 40 receives the temperature of the fumigant exiting the device outlet 3 from the temperature sensor 72. In block 620, the controller determines whether the measured temperature is too low or too high compared to the desired target temperature ("predetermined temperature"). If the measured temperature is too low, then in block 630, the controller 40 determines a target flow rate or flow rate change to deliver the desired target temperature for the output fumigant. In block 640, the controller determines adjustments to the control parameters of the gas regulator, pump, or compressor to deliver the target flow rate or flow rate change determined in block 630. In block 650, the controller controls the gas regulator, pump, or compressor according to the adjustments to the control parameters determined in block 640. Thus, in Figure 6, it is understood that blocks 610-630 function as the outer control loop, and blocks 640-650 function as the inner control loop.

[0058] The controller 40 may be a PID controller. In some examples, the controller may use the measured output temperature as a process value, with the desired output temperature of the fumigant as the setpoint. The control variable may be the pressure of the regulator. In some examples, the first control loop may target the output temperature and output a desired flow rate as the setpoint of the second control loop, and the second control loop may measure the flow rate as a process variable and control the pressure of the regulator as a control variable.

[0059] Figure 7 shows an example configuration of a PID controller 700 according to an example of the present disclosure. The controller takes a target temperature 710 of the fumigant as a setpoint. A comparator 720 compares the target temperature with the actual temperature 770 at outlet 3 measured by a temperature sensor 72. The comparator 720 outputs the result of this comparison to a step function F(x) 730 that maps the comparator output (temperature difference) to a target flow rate. The step function F(x) 730 outputs the target flow rate to a second comparator 740, which compares the target flow rate with the actual flow rate of the gas in the first channel 10, measured by a flow meter 19. The second comparator 740 outputs the difference between the target and the measured flow rate as input to a PID module 750. The PID module 750 determines the adjustment to the control parameters of the gas regulator 760 to satisfy the target flow rate and controls the gas regulator accordingly. Through the fluid dynamics of the fumigation apparatus (conceptually denoted by F(x)), this will eventually reach the target output temperature. In this way, the controller dynamically adjusts the flow rate of the high-temperature gas stream to maintain the temperature of the fumigant exiting the apparatus at the desired level.

[0060] The gas source 11 may be a source of inert gas. In some examples, the gas is one or more of nitrogen, carbon dioxide, or helium. The gas source may be located in a container or tank suitable for storing compressed gas, such as a cylinder, which has a volume that provides a sufficient amount of gas for at least one treatment application of a chemical agent as a fumigant. In other examples, the gas source 11 may be a gas generator that can produce a sufficient amount of inert gas as needed by extracting it from the atmosphere. Non-limiting examples include pressure swing adsorption (PSA) or membrane separation (MS) nitrogen generators. In one embodiment, the gas source is a nitrogen generator capable of producing high-quality (>99%) nitrogen gas. The nitrogen generator provides dry, filtered, heated air through a specially designed group of filtration membranes. These membranes separate nitrogen from CO2 and O2 exhaust gases, and the nitrogen is passed through a delivery pipe or other suitable conduit for delivery to the inlet of the regulator 12.

[0061] The second inlet 62 of the mixing chamber may be equipped with a nozzle for spraying the liquid chemical agent before or when the liquid chemical agent enters the mixing chamber. The nozzle may be, for example, coplanar with the wall of the mixing chamber or extend in a short length into the mixing chamber. By spraying the liquid chemical agent, the nozzle promotes a more rapid vaporization of the chemical agent when it comes into contact with the hot gas flow in the mixing chamber. In some examples, the nozzle is a hydraulic spray nozzle. A hydraulic spray nozzle is a nozzle that receives a flow of liquid and sprays the liquid without mixing the liquid with a separate gas flow. A hydraulic spray nozzle can be contrasted with an air or gas spray nozzle, which mixes the flow of liquid with the gas to achieve spraying. The use of a hydraulic spray nozzle may slow down vaporization in the mixing chamber compared to the use of an air or gas spray nozzle, which may help avoid overheating or rapid heating of the apparatus.

[0062] In some examples, as shown in Figure 4, for instance, the mixing chamber 60 is shaped such that the first inlet 62 of the mixing chamber is at the first end of the mixing chamber and the second inlet 64 of the mixing chamber is at the second end of the mixing chamber opposite the first end, so that the hot gas flow 56 and the chemical agent flow 26 enter the mixing chamber from opposite directions. This helps to generate turbulence, which enhances the mixing of the chemical fumigant and the hot gas, promotes the vaporization of the chemical fumigant, and helps to ensure a more uniform distribution of the fumigant in the fumigant / gas mixture. In some examples, the outlet 66 of the mixing chamber is located on the side wall joining the first and second ends of the mixing chamber, so that the mixed flow of hot gas and chemical fumigant exits the mixing chamber through the outlet 66 in a direction substantially perpendicular to the direction in which the hot gas flow 56 and the chemical agent flow 64 enter the mixing chamber.

[0063] As mentioned above, the gas regulator 12 can be in fluid communication with the gas source 11 via the inlet 1. The gas regulator 12 controls the pressure of the gas in the section of the first channel 10 in front of the heater 50. The pressure of the gas regulator can be controlled by a controller to deliver a desired flow rate of gas in the first channel and / or the temperature of the output fumigant from the device, as described above. In some examples, the pressure may be 2-3 bar. In some examples, the flow rate of gas in the first channel, measured by the flow meter 19, may be 300-400 liters / minute. In some implementations, flow rates much higher than this may risk overheating the device and / or causing damage to internal components.

[0064] The gas regulator 12 may be in fluid communication with the heater 50. The gas regulator 12 may allow the gas flow to be directed from the gas regulator 12 to the heater 50 along the first channel 10. The heater 50 may be an inline air heater in which gas enters through a heater inlet 52 at a first end and heated gas exits through a heater outlet 54 at a second end. The heater 50 may be designed for substantial gas flow and rapid heating of the gas introduced into the heater 50. The heater 50 may be capable of heating the gas introduced into the heater 50 to a considerable temperature while substantially maintaining the ambient temperature on the outside of the heater 50. The heater 50 may be powered from a power source (not shown), such as a single-phase power supply.

[0065] The fumigation apparatus may include a second temperature sensor 56 for measuring the temperature of the hot gas in a first channel 10 near the heater 50 and transmitting information about the measured temperature to a controller 40. The controller 40 may dynamically adjust the temperature of the heater 50 using a PID loop targeting a specified temperature. An exemplary configuration of the PID control loop 800 for the heater is shown in Figure 8. The desired heater temperature 810 is used as a setpoint input to a comparator 820. The comparator compares the desired temperature 810 with the actual temperature 850 measured by the second temperature sensor 56. The comparator 820 determines the appropriate adjustment to the control parameters of the heater 840 (such as input current or voltage) and controls the heater 840 accordingly, outputting the difference to a PID module 830 that achieves the desired heater temperature. As mentioned above, the desired heater temperature may be fixed throughout the process and set to a level that maximizes throughput without exceeding an upper limit that could damage the components of the fumigation apparatus.

[0066] The controller 40 can control both the on / off function of the heater 20 and the temperature management. In some examples, the heater 20 is programmed to heat to a temperature of approximately 180°C to 500°C. In some examples, it is approximately 240°C to 320°C, or up to approximately 500°C. A higher heater temperature results in a higher gas flow rate, but still heats the gas to a sufficient temperature. The heater temperature can be kept at a constant level throughout the fumigation process. Often, the apparatus can operate the heater at or near its maximum temperature to maximize flow rate, vaporize the chemicals, and reduce the time required to apply the fumigants. The heater temperature should be selected to be below a level that would damage internal components of the apparatus, such as pipes or tubes forming the first channel between the heater and the mixing chamber. For this reason, in some examples, the temperature of the gas leaving the heater can be kept below 320°C.

[0067] The higher the boiling point of a chemical agent, the more energy is required to vaporize it. Ethyl formate has the highest boiling point of any commercially available chemical agent commonly used in fumigation. Therefore, the apparatus 100 can be used to vaporize other chemical agents with lower boiling points, such as methyl bromide and propylene oxide, but is not limited to these. The apparatus 100 can be used to vaporize a variety of chemical agents, including flammable and non-flammable agents, by appropriately adjusting and controlling the temperature of the heater 50 during use.

[0068] The gas enters the heater 50 at the first end 52 or adjacent to the first end 52, where it may be heated to a desired temperature inside the heater 50 and exits from the opposite end via the heater outlet 54. The temperature of the heater 50 can be much higher than the temperature of the fumigant exiting the fumigation apparatus due to cooling as the gas passes through the first channel 10 from the heater outlet 54 to the inlet 62 of the mixing chamber 60, as well as cooling by the potential thermal energy taken to vaporize the liquid chemical agent in the mixing chamber 60 and vaporization coil 70. Therefore, the temperature of the flow of the hot gas and chemical fumigant exiting the mixing chamber outlet 66 and the fumigation apparatus outlet 3 may be lower than the temperature of the heater 50. In some examples, the heater may heat the gas to 300-400°C, and the temperature of the mixture of the hot gas and vaporized chemical agent exiting the fumigation apparatus outlet may be 54-70°C.

[0069] The chemical agent pump 22 may be positioned in fluid communication with the source of the chemical agent 13. The source of the chemical agent 13 may be outside the apparatus 100 and separated from the apparatus 100, allowing the apparatus 100 to draw, channel, and utilize the chemical agent from any source or container of any size, providing the apparatus 100 with a substantially unlimited source of chemical agents. This offers a significant advantage over conventional vaporization devices, where the volume of the chemical agent, and therefore the scope of application of the vaporization device, is limited by the volume of the container, canister, or other such chamber that forms part of the device itself. Maintaining a separate source of chemical agents from the apparatus 100 also provides a safety advantage, as little chemical agent remains in the apparatus 100 after use, reducing toxicity and / or flammability risks.

[0070] In some cases, liquid chemicals can be pumped at a rate of 15–17 liters / hour. In some cases, it is approximately 15.8 liters / hour. In some cases, the rate can be set so that the delivery of the fumigant to the area to be fumigated can be completed within 10–15 minutes. In some cases, the pumping rate by the chemical pump can be set so that 3 liters of liquid chemical can be vaporized and delivered as fumigant within 10–15 minutes, and in some cases within approximately 14 minutes. The ratio of high-temperature gas to vaporized chemical in the fumigant output from the mixing chamber and fumigation device outlet depends on the respective flow rates of the gas and liquid chemicals. As mentioned above, the gas flow rate is mainly used to control the output temperature and maintain the output temperature above a specific predetermined temperature. However, the concentration of fumigant in the output mixture must not exceed a safe level for human operation, and in the case of flammable chemicals, it should be kept below the lower explosive limit (LEL). The lower explosive limit of ethyl formate is approximately 2.8% of vaporized ethyl formate relative to the volume of non-flammable gas (e.g., nitrogen), or 92 g / m³ of ethyl formate. 3 In some cases, it was found that for every 3 liters of liquid ethyl formate pumped into the mixing chamber, 4,500 to 6,000 liters of non-flammable gas (measured by a flow meter) were introduced into the mixing chamber.

[0071] Some known fumigation devices require measuring a certain amount of chemical agent before each use and introducing it into the device's container, necessitating the handling of the chemical agent and increasing the risk of exposure to potentially toxic substances. This risk is reduced by the device 100, as it eliminates the need for the operator to measure and introduce a certain amount of chemical agent. These known fumigation devices typically heat the chemical agent in the container. If the container is not sufficiently cooled between applications of the chemical agent, the introduction of the chemical agent into the container will cause the agent to evaporate upon contact with the high-temperature elements within the container. Therefore, once the device has depleted a certain amount of chemical agent, it must be stopped and cooled before it can be refilled. The device 100 avoids the need to provide a cooling period between each application of the chemical agent, thereby enabling improved operational efficiency.

[0072] As shown in Figure 2, the heater 50 may be positioned above the mixing chamber 60 to prevent condensed chemicals from the mixing chamber 60 from dripping onto the heater 50, which poses a fire hazard due to the flammable nature of certain chemicals.

[0073] The first channel 10 may comprise one or more tubes of flexible material. The first channel may further comprise one or more pipes of heat-resistant material, such as metal, adjacent to the heater 50 and connecting from the outlet of the heater 54 to the first inlet of the mixing chamber 62. The second channel may comprise one or more pipes of flexible material connecting the inlet 2 to the chemical agent pump 22 and the second inlet 64 of the mixing chamber. The second channel may contain or be coated with a corrosion-resistant material. For example, a material that can transport chemical agents such as organic solvents without significant degradation, such as silicone, polyethylene, fluorinated ethylene propylene, or Teflon. The mixing chamber 60 may, but is not limited to, be formed of a heat-resistant and corrosion-resistant material such as stainless steel.

[0074] The fumigation apparatus may have a third channel 30 which functions as a purge line. The third channel 30 is in fluid communication with the gas source 11 and joins a second channel 20 upstream of the mixing chamber 60. As shown in Figure 4, the third channel 30 may have a valve 34, such as a solenoid valve, which, when opened, allows a gas flow to pass through the third channel 30 to the second channel 20, thus purging the chemical agent from the second channel 20. This helps maintain the long life of the fumigation apparatus, as it has been found that prolonged exposure can cause degradation and failure, especially if the channel is not cleaned and chemical residues remain in the second channel, even if the second channel is formed of or coated with a corrosion-resistant material. Purge may be used when the fumigation device is subsequently used with a different fumigant to prevent unwanted chemical reactions within the apparatus.

[0075] A third channel 30 may be connected to the first channel 10 via a purge regulator 32. The purge regulator and / or purge valve 34 may act to prevent backflow of the chemical agent into the first channel. In other examples, a separate one-way valve may be provided for this purpose. In the illustrated example, the purge valve 34 is a bidirectional valve that, in a first state, connects the purge regulator 32 and / or the first channel 10 to a second channel downstream of the purge valve 34, and in a second state, connects the chemical agent source and / or the second channel upstream of the purge valve 34 to a second channel downstream of the purge valve that connects toward the second inlet 64 of the mixing chamber.

[0076] In some examples, as shown in Figure 4, the chemical agent pump 22 is located downstream of the point where the third channel 30 joins the second channel 20 (i.e., downstream of the purge valve 34) so ​​that the chemical agent pump can be purged. This prevents pump degradation, which has surprisingly been found to occur even in corrosion-resistant pumps due to the corrosive nature of certain chemical fumigants.

[0077] As shown in Figure 4, the controller 40, gas regulator 12, pump 22, and gas flow meter 19 may be contained within a housing 102 configured to provide an oxygen-reduced environment 8. As shown, other components, particularly electronically controlled components, may also be contained within the oxygen-reduced environment to reduce the risk of fire. A portion of the first channel 10 passing through the housing 102 may include a purge vent 16 for injecting gas from a gas source 11 into the housing to release oxygen from the housing. In this way, an oxygen-reduced environment can be achieved. An oxygen sensor 42 may be located inside the housing 102, and the controller 40 may be configured to turn off the heater 50 in response to the oxygen sensor detecting oxygen in the housing. Since the same gas source 11 is used to purge the housing and supply gas that is heated by the heater, the oxygen sensor can therefore detect whether any significant level of oxygen is present in the gas flowing into the heater. In response to detecting an oxygen level above a certain threshold, the controller 40 may automatically switch off the heater 50 to prevent or reduce the risk of fire. The controller 40 may continue to supply gas to the heater 50 through the channel 10 to cool the heater during the period after the heater has been shut down.

[0078] The fumigation apparatus 100 described herein has utility for surface application, including the treatment of empty containers to reduce the risk of pest infestation when materials such as bulk goods are introduced into the containers.

[0079] A fumigation method using the fumigation apparatus 100 described above may include: flowing an inert gas through a first channel 10 to a heater 50 to heat the inert gas and allowing the heated inert gas to enter a mixing chamber 60; pumping a liquid fumigant through a second channel 20 to the mixing chamber 60; mixing the liquid fumigant and the heated inert gas in the mixing chamber 60 to form a fumigant containing a mixture of high-temperature gas and vaporized fumigant in the mixing chamber 60, allowing the flow of the fumigant to exit the mixing chamber and directing the fumigant from the outlet of the fumigant apparatus to the area to be fumigated. The mixture of gas and chemical agent exiting from outlet 3 may be applied as a thin film to the surface of the treatment area, giving the surface a wet appearance, but can evaporate rapidly from the surface being treated. The surface temperature of the treated surface, raised by the application of the high-temperature gas flow, is used to complete the evaporation of the chemical agent.

[0080] In some examples, the inert gas may be one or more of nitrogen, helium, and carbon dioxide. In some examples, the liquid fumigant may be ethyl formate, propylene oxide, or methyl bromide. In some examples, the liquid fumigant is ethyl formate.

[0081] During use, the chemical agent 13 supply source and the gas source 11 may be locally located in the apparatus 100 and the area requiring treatment. The gas source 11 and the chemical agent source 13 are connected to the apparatus 100 via a first inlet 1 and a second inlet 2, respectively. If the gas source is a gas generator such as a nitrogen generator, the gas source is operated until the required gas purity is achieved. If the gas source is nitrogen, it is preferable that a nitrogen purity of >99%, more preferably about >99.4%, is achieved.

[0082] The chemical agent is drawn into the apparatus 100 by the action of the pump 22 and directed through the second channel 20 to the second inlet 64 of the mixing chamber 60. The gas can be channeled by the gas regulator 12 through the first channel 10 from the gas source 11 to the heater 50. The heater 50 can be operated by the controller 40 as described above, and the pressure of the gas regulator can be controlled by the controller.

[0083] The gas is heated in heater 50, and the hot gas exits through heater outlet 54 and is directed to the first inlet 62 of mixing chamber 60. The hot gas stream 56 is then brought into contact with a stream of liquid chemical particles entering the mixing chamber 64 through a nozzle (not shown) at the second inlet 64, thereby vaporizing the liquid particles and mixing them with the vaporized chemical particles in the mixing chamber 60 and vaporization coil 70 to form a vaporized chemical / gas mixture. This vaporized chemical / gas mixture is a suitable fumigant for application to the treatment area. The chemical / gas mixture is directed to outlet 3 and exits from outlet 3, and can be applied to the treatment area by an insulated delivery tube (not shown).

[0084] Once fumigation of the treatment area is complete, the apparatus 100 can be switched off or powered off by stopping the flow of gas and chemicals. The apparatus 100 can then be used for further treatment applications at any time as needed. Vaporizing the chemicals and applying the fumigant may take 10 to 40 minutes depending on the size of the shipping container, warehouse, or area to be fumigated, but fumigation typically takes several hours as the fumigant is left for a certain amount of time to settle and act on the applied surface.

[0085] If further processing applications require the use of chemicals different from those used in previous applications, the apparatus 100 may be purged with gas as described above, or flushed or washed with a liquid suitable for removing residues of the first chemical. Since no chemicals are stored in the apparatus 100 and the vaporization of the chemicals is substantially completed in any application, there is little chemical residue remaining in the apparatus 100 after use, which significantly speeds up the cleaning process.

[0086] Those skilled in the art will understand that numerous variations and / or modifications can be made to the embodiments described above without departing from the broad general scope of this disclosure. Accordingly, these embodiments should be considered in all respects as illustrative and not limiting.

Claims

1. A fumigation device, A mixing chamber including a first inlet for receiving a flow of high-temperature gas, a second inlet for receiving a flow of chemical fumigant, and a mixing chamber outlet for outputting a mixed flow of high-temperature gas and chemical fumigant, A gas regulator, pump, or compressor for directing the flow of non-combustible gas along a first channel from a non-combustible gas source to the first inlet of the mixing chamber, To provide a flow of high-temperature gas to the first inlet of the mixing chamber, a heater for heating the flow of non-combustible gas in the first channel, A chemical agent pump for directing the flow of the chemical fumigant along a second channel from the chemical fumigant supply source to the second inlet of the mixing chamber, In order to discharge the mixed flow of the high-temperature gas and the chemical fumigant, the fumigation device outlet is in fluid communication with the outlet of the mixing chamber, A temperature sensor for measuring the temperature of the mixed flow of the gas and chemical fumigant discharged from the outlet of the fumigation device, A fumigation apparatus comprising: a controller for controlling the gas regulator, pump or compressor and / or the chemical agent pump based on the temperature measured by the temperature sensor, to maintain the flow of the high-temperature gas and chemical fumigant exiting the fumigation apparatus outlet at a predetermined temperature or higher.

2. The fumigation apparatus according to claim 1, further comprising a gas flow meter for measuring the flow rate of the gas flow in the first channel, wherein the controller is configured to control the gas regulator, pump or compressor, and / or the chemical agent pump at least in part based on the flow rate measured by the gas flow meter.

3. The fumigation apparatus according to claim 1 or 2, wherein the controller uses a negative feedback loop to control the gas regulator, pump, or compressor and dynamically adjust the flow rate of the gas through the first channel so as to maintain the output temperature of the mixed flow of the high-temperature gas and chemical fumigant above a predetermined temperature.

4. The fumigation apparatus according to any one of the above claims, wherein the controller controls the gas regulator, pump, or compressor based on the temperature measured by the temperature sensor, and the chemical agent pump is independent of the temperature measured by the temperature sensor and / or the gas flow rate measured by the gas flow meter.

5. The fumigation apparatus according to any one of the above claims, wherein the predetermined temperature is at least 54 degrees Celsius.

6. The fumigation apparatus according to any one of the above claims, wherein the temperature of the flow of the high-temperature gas and chemical fumigant exiting the outlet of the fumigation apparatus is lower than the temperature of the heater.

7. The fumigation apparatus according to any one of the above claims, wherein the controller is configured to control the gas regulator, pump, or compressor so that 4,500 to 6,000 liters of gas flow through the first channel for every 3 liters of chemical fumigant pumped through the second channel by the chemical agent pump.

8. The fumigation apparatus according to any one of the above claims, wherein the second inlet of the mixing chamber is provided with a nozzle for spraying the liquid chemical agent that enters the mixing chamber.

9. The fumigation apparatus according to claim 8, wherein the nozzle is a hydraulic spray nozzle.

10. The fumigation apparatus according to any one of the above claims, wherein the first inlet of the mixing chamber is located at the first end of the mixing chamber, and the second inlet of the mixing chamber is located at the second end opposite to the first end of the mixing chamber, so that the high-temperature gas flow and the chemical agent flow enter the mixing chamber from opposite directions so as to generate turbulence.

11. The fumigation apparatus according to claim 10, wherein the outlet of the mixing chamber is positioned on a side wall joining the first end and the second end of the mixing chamber, and so the mixed flow of the high-temperature gas and the chemical fumigant exits the mixing chamber through the outlet in a direction substantially perpendicular to the direction in which the high-temperature gas flow and the chemical agent flow enter the mixing chamber.

12. The fumigation apparatus according to any one of the above claims, further comprising a vaporization coil having a first end that is in fluid communication with the outlet of the mixing chamber and a second end that forms the outlet of the fumigation apparatus or is in fluid communication with the outlet of the fumigation apparatus.

13. A fumigation apparatus according to any one of the above claims, having a third channel which functions as a purge line, the third channel being in fluid communication with the gas source and joined to a second channel upstream of the mixing chamber, and the third channel having a valve which, when opened, allows the gas flow to pass through the third channel to the second channel and purge the chemical agent in the second channel.

14. The fumigation apparatus according to claim 13, wherein the chemical agent pump is located downstream of the point where the third channel joins the second channel, so that the chemical agent pump can be purged.

15. The fumigation apparatus according to any one of the above claims, wherein the controller, gas regulator and pump, and gas flow meter are contained within a housing configured to provide an oxygen-reducing environment.

16. The fumigation apparatus according to claim 15, wherein a portion of the first channel passing through the housing includes a purge vent for injecting gas from a gas source into the housing so as to release oxygen from the housing.

17. The fumigation apparatus according to claim 15 or 16, wherein an oxygen sensor is provided inside the housing, and the controller is configured to turn off the heater in response to the oxygen sensor detecting oxygen in the housing.

18. The fumigation apparatus according to any one of the above claims, wherein the heater is positioned above the mixing chamber.

19. A fumigation apparatus according to any one of the above claims, wherein the second channel comprises a corrosion-resistant material; at least the portion of the first channel extending from the heater to the mixing chamber comprises a heat-resistant material; the vaporization coil is heat-resistant and corrosion-resistant; the second channel and the portion of the first channel extending from the regulator to the heater are formed of a flexible material; and the flexible material of the second channel is coated with a corrosion-resistant material.

20. The fumigation apparatus according to any one of the above claims, wherein the chemical fumigant is ethyl formate.

21. The fumigation apparatus according to any one of the above claims, wherein the non-flammable gas is an inert gas.

22. The fumigation apparatus according to any one of the above claims, wherein the gas source is located outside the fumigation apparatus.

23. The fumigation apparatus according to any one of the above claims, wherein the chemical agent source is located outside the fumigation apparatus.

24. The fumigation apparatus according to any one of the claims, further comprising a second temperature sensor for measuring the temperature of the hot gas in the first channel near the heater and transmitting information regarding the measured temperature to the controller, wherein the controller is configured to control the heater.

25. A fumigation device, A mixing chamber including a first inlet for receiving a flow of high-temperature gas, a second inlet for receiving a flow of chemical fumigant, and a mixing chamber outlet for outputting a mixed flow of high-temperature gas and chemical fumigant, A gas regulator / pump / compressor for directing the flow of non-combustible gas along a first channel from a non-combustible gas source to the first inlet of the mixing chamber, To provide a flow of high-temperature gas to the first inlet of the mixing chamber, a heater for heating the gas flow in the first channel of the mixing chamber, A chemical agent pump for directing the flow of chemical fumigant along a second channel from the chemical fumigant supply source to the second inlet of the mixing chamber, To discharge the mixed flow of the high-temperature gas and the chemical fumigant, the fumigation device outlet is in fluid communication with the outlet of the mixing chamber, A fumigation apparatus in which the first inlet of the mixing chamber is located at the first end of the mixing chamber, and the second inlet of the mixing chamber is located at the second end opposite to the first end of the mixing chamber, so that the high-temperature gas flow and the chemical agent flow enter the mixing chamber from opposite directions so as to generate turbulence.

26. A fumigation method using a fumigation apparatus described in any one of the above claims, The inert gas is made to flow through the first channel to the heater, heat the inert gas, and allow the heated inert gas to enter the mixing chamber. The liquid fumigant is pumped into the mixing chamber through the second channel, A method comprising: mixing the liquid fumigant and the heated inert gas in the mixing chamber to form a fumigant containing a mixture of the high-temperature gas and the vaporized fumigant in the mixing chamber; allowing the flow of the fumigant to exit the mixing chamber; and directing the fumigant from the outlet of the fumigant apparatus to a region to be fumigated.

27. The method of Cram 26, wherein the inert gas is selected from the group including nitrogen, helium, and carbon dioxide.

28. The method according to claim 26 or 27, wherein the liquid fumigant is ethyl formate.

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