Sterilization apparatus, sterilization equipment, sterilization method, and method for producing sterilized granular material

Abstract

It sterilizes all granular materials evenly and completes the sterilization process in a short amount of time. [Solution] The sterilization device 10 comprises a tank 11 for containing granular material to be sterilized, and a gas supply device 12 for supplying chlorine dioxide gas to the inside of the tank 11 from below. The gas supply device 12 sterilizes the granular material inside the tank 11 while causing it to flow by blowing out chlorine dioxide gas.

Description

[Technical Field]

[0001] This matter relates to a sterilization device and method for sterilizing granular materials, as well as a sterilization facility equipped with this sterilization device, and also to a method for producing sterilized granular materials. [Background technology]

[0002] Conventionally, methods have been used to sterilize microorganisms (bacteria, fungi) and viruses attached to granular materials such as seeds, grains, sand, and gravel, including immersion in disinfectant solutions, dusting with disinfectant powder, and dry heat treatment. When granular materials are to be finished in a dry state, immersion and dusting methods require a drying process after immersion in liquid or wet powder, raising concerns about prolonged sterilization treatment time. Furthermore, if the wetting and drying process damages the granular material itself, sterilization must be performed in a dry state, making immersion and dusting methods unusable. On the other hand, dry heat treatment does not require wetting the granular material, thus eliminating the need for the wetting and drying process, and this process does not damage the granular material (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4198127 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, dry heat treatment methods have drawbacks, such as high energy consumption due to the use of high-temperature gases, and the inability to use them when granular materials are damaged by high temperatures. In contrast, a technology is known that uses chlorine dioxide gas to kill microorganisms and sterilize. Sterilization methods using chlorine dioxide gas can be performed while the material is in a dry state, and the treatment time can be shortened by adjusting the gas concentration, thus reducing energy consumption.

[0005] However, simply filling a container with granular material to be sterilized and filling the container with chlorine dioxide gas is insufficient. If the granular material is thick or clumped together, the chlorine dioxide gas may not reach the inside of the layers or clumps. As a result, it is difficult to sterilize all the granular material evenly and thoroughly, and there is a problem that some granular material may not be sterilized sufficiently.

[0006] The sterilization apparatus, sterilization equipment, and sterilization method described herein were devised in view of these problems, and one of their objectives is to sterilize all granular materials evenly and to complete the sterilization process in a short time. Furthermore, one of the objectives of the method for producing sterilized granular materials described herein is to produce uniformly sterilized granular materials in a short time. In addition to these objectives, another objective of this invention is to achieve effects and advantages that cannot be obtained by conventional technology, which are derived from the various configurations shown in the embodiments for carrying out the invention described later. [Means for solving the problem]

[0007] The disclosed sterilization apparatus, sterilization equipment, sterilization method, and method for producing sterilized granular material can be realized in the embodiments (application examples) disclosed below, and solve at least some of the above problems. Embodiments 1 to 4 relate to sterilization apparatus, and embodiments 5 to 7 relate to sterilization equipment. Embodiments 8 and 9 relate to sterilization methods, and embodiment 10 relates to a method for producing sterilized granular material. Embodiments 2 to 4, embodiments 6 to 7, and embodiment 9 are all embodiments that can be optionally selected, all of which are optional, and none of which disclose embodiments or configurations that are indispensable to this case.

[0008] Embodiment 1. The sterilization apparatus disclosed comprises a tank for containing granular material to be sterilized, and a gas supply device for supplying chlorine dioxide gas into the tank from below, wherein the gas supply device sterilizes the granular material inside the tank while causing it to flow by blowing out the chlorine dioxide gas. Embodiment 2. In Embodiment 1 described above, the tank is preferably cylindrical and has a mesh-like surface on which the granular material is placed and through which the chlorine dioxide gas flows, and the gas supply device preferably has a generator for generating the chlorine dioxide gas and a supply path for supplying the chlorine dioxide gas generated by the generator to the tank.

[0009] Embodiment 3. In Embodiment 1 or 2 described above, it is preferable to further include a decomposition device that takes in the gas inside the tank and decomposes the chlorine dioxide gas. Embodiment 4. In any one of embodiments 1 to 3 above, it is preferable that the discharge speed of the chlorine dioxide gas into the tank is equal to or greater than the minimum fluidization speed and less than the slugging initiation speed.

[0010] Embodiment 5. The disclosed sterilization equipment comprises a sterilization device according to any one of Embodiments 1 to 4 above, a sterilization area in which the tank of the sterilization device is located and which can be sealed, a barrier area encompassing the sterilization area and which can be sealed, and a work area encompassing the barrier area and in which an operating unit for the sterilization device is located and in which an operator operates the operating unit.

[0011] Embodiment 6. In Embodiment 5 described above, the sterilization equipment preferably comprises an air supply passage for drawing air from the work area into the barrier area, interposed with a backflow prevention damper; a decomposition device for the barrier area for decomposing the chlorine dioxide gas in the barrier area; a concentration meter for detecting the concentration of the chlorine dioxide gas in the barrier area; and an exhaust passage for discharging the gas in the barrier area to the outside.

[0012] Embodiment 7. In Embodiment 5 or 6 described above, it is preferable that the sterilization equipment comprises a humidifier located in the sterilization area, a temperature control device located in the sterilization area or the barrier area, a temperature sensor for detecting the temperature in the sterilization area, and a humidity sensor for detecting the humidity in the sterilization area.

[0013] Aspect 8. The disclosed sterilization method involves containing particulate matter to be sterilized inside a tank, supplying chlorine dioxide gas from below into the interior of the tank, and sterilizing while causing the particulate matter inside the tank to flow by the blowing of the chlorine dioxide gas. Aspect 9. In the above Aspect 8, it is preferable that the blowing rate of the chlorine dioxide gas into the interior of the tank is not less than the minimum fluidization rate and less than the starting rate of slugging.

[0014] Aspect 10. The disclosed method for manufacturing sterilized particulate matter involves containing particulate matter to be sterilized inside a tank, supplying chlorine dioxide gas from below into the interior of the tank, sterilizing for a predetermined period while causing the particulate matter inside the tank to flow by the blowing of the chlorine dioxide gas, and then taking out the particulate matter from the tank.

Advantages of the Invention

[0015] According to the disclosed sterilization apparatus, sterilization equipment, and sterilization method, it is possible to sterilize all particulate matter uniformly and complete the sterilization process in a short time. Also, according to the disclosed method for manufacturing sterilized particulate matter, it is possible to manufacture uniformly sterilized particulate matter in a short time.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic diagram showing a sterilization apparatus according to an embodiment. [Figure 2] It is a schematic diagram showing sterilization equipment according to an embodiment. [Figure 3] It is a flowchart for explaining a sterilization method and a method for manufacturing sterilized particulate matter according to an embodiment. [Figure 4] It is a graph for explaining the operation of a sterilization apparatus and a sterilization method according to an embodiment.

Modes for Carrying Out the Invention

[0017] Referring to the drawings, a sterilization device, sterilization equipment, sterilization method, and method for manufacturing sterilized granular materials as embodiments will be described. The sterilization device, sterilization equipment, and sterilization method of this embodiment are respectively devices, equipment, and methods related to the sterilization of granular materials, and all sterilize the granular materials while flowing them with chlorine dioxide gas. As a result, all the granular materials are sterilized evenly. Further, the method for manufacturing sterilized granular materials is a method for creating granular materials sterilized using the sterilization method of this embodiment.

[0018] The following embodiments are merely examples, and there is no intention to exclude various modifications and applications of technologies not explicitly stated in the following embodiments. Each configuration of the embodiments can be implemented with various modifications without departing from their gist. Also,取舍 selection can be made as necessary, or they can be appropriately combined. In the following description, first, the sterilization device will be described, then the sterilization equipment equipped with this sterilization device will be described, and then the sterilization method and the method for manufacturing sterilized granular materials will be described.

[0019] [1. Sterilization Device] FIG. 1 is a schematic diagram showing a sterilization device 10 according to this embodiment. The sterilization device 10 includes a tank 11 (exposure tank) for accommodating granular materials (granular objects) to be sterilized, and a gas supply device 12 for supplying chlorine dioxide gas (hereinafter, also simply referred to as "gas") downward into the interior of the tank 11. Note that the white arrows in FIG. 1 and FIG. 2 described later indicate the direction in which the gas (air, chlorine dioxide gas, a mixture thereof) flows. In FIG. 1, the entire granular materials accommodated (filled) inside the tank 11 are schematically shown by a dashed-line cylinder, but actually, a large number of fine granular materials are accommodated inside the tank 11.

[0020] Examples of granular materials to be sterilized include seeds, grains, pet food, gardening sand and gravel, soil for plant factories, and raw materials for clothing. Even if granular materials are of the same type (for example, a given seed), there are individual differences and they are not necessarily the same shape, and they come in various shapes such as spheres, ellipsoids, ovals, and columns. In the sterilization device 10 of this embodiment, the gas supply device 12 sterilizes the granular materials inside the tank 11 by blowing out chlorine dioxide gas to make them flow. Hereinafter, this sterilization method will also be called the "blowing exposure method". As a result, all granular materials contained inside the tank 11 are sterilized evenly, regardless of their shape or type.

[0021] In this context, "fluidization" refers to a state in which the weight of each granular material is counteracted by the blowing of chlorine dioxide gas, causing the granular material to move rather than remain in one place (a so-called fluidized state). Generally known forms of fluidization include minimal fluidization, uniform fluidization, and bubble fluidization. As the gas flow rate increases, the granular material filling the tank 11 and forming a fixed layer changes its form in the order of minimal fluidization, uniform fluidization, and bubble fluidization. In the sterilization device 10 of this embodiment, the blowing speed of chlorine dioxide gas is set so that one of these three states is achieved.

[0022] For example, the rate at which chlorine dioxide gas is blown into the tank 11 may be set to be greater than or equal to the minimum fluidization rate and less than the slugging initiation rate. mf Generally, it can be expressed by the following equations 1 to 3. Note that D P Φ is the particle diameter, Φ is the particle shape factor, ε mf ρ is the porosity of the minimum fluid state. s ρ is the density of particles. g μ is the density of the fluid, μ is the viscosity of the fluid, and g is the acceleration due to gravity.

[0023]

number

[0024] Also, the slugging start speed u msFor example, the following equation 4 can be used. Note that D t This is the diameter of the tank 11.

number

[0025] At discharge speeds below the minimum fluidization speed, the granular material is less likely to change from the fixed layer. On the other hand, when slugging occurs, the granular material flows, but some of it remains in the same state as the fixed layer (i.e., some of the granular material does not move). Therefore, by setting the discharge speed range to be above the minimum fluidization speed of the granular material and below the slugging initiation speed of the granular material, an appropriate fluidization state can be achieved.

[0026] The tank 11 in this embodiment is cylindrical. Specifically, the tank 11 is a cylindrical body with a uniform cross-section that extends vertically when installed in a predetermined location, for example, an elongated cylindrical body whose vertical length is longer than the diameter of its cross-section. The tank 11 has a mesh-like mounting surface 11a on which granular material is placed and through which chlorine dioxide gas flows. The coarseness of the mesh of the mounting surface 11a is set to a size that prevents granular material from falling through and allows gas to flow through. The upper surface of the tank 11 may be provided to be closable depending on the space filled with chlorine dioxide gas, as described later, or it may be left open at all times.

[0027] In the sterilization device 10 shown in Figure 1, chlorine dioxide gas fills only the inside of the tank 11, except for the gas supply device 12. In this configuration, the top surface of the tank 11 is provided to be closable, for example, by an openable and closable lid. On the other hand, in the sterilization device 10' described later using Figure 2, chlorine dioxide gas fills not only the inside of the tank 11 but also the space where the tank 11 is installed. In this configuration, the top surface of the tank 11 may be left open at all times, or it may be covered with a mesh of a coarseness similar to that of the mounting surface 11a, for example, to prevent the granular material in a fluid state from flying out from the top surface of the tank 11. In either configuration, the granular material is contained (filled) into the tank 11 from the top surface and sterilized while becoming fluid due to the blowing out of chlorine dioxide gas supplied from the entire area below the mounting surface 11a.

[0028] As shown in Figure 1, the gas supply device 12 includes a generator 12a that generates chlorine dioxide gas and a gas supply passage 12b (supply passage) that supplies the chlorine dioxide gas generated by the generator 12a to the tank 11. The generator 12a may, for example, include a container into which pelletized sodium chlorite is introduced and a tank that stores an acidic liquid, and generate chlorine dioxide gas by chemically reacting the pelletized sodium chlorite with the acidic liquid by supplying the acidic liquid from the tank to the container via a nozzle. Note that the generator 12a may be configured with well-known configurations such as those described in Japanese Patent No. 6162455, Japanese Patent No. 6835904, and Japanese Patent No. 7111490.

[0029] The gas supply passage 12b is a passage that connects the generator 12a and the lower end of the tank 11. A main blower 12d that generates the gas flow is interposed in this gas supply passage 12b. The main blower 12d may be a simple fan or a pressure pump, and there is no limit to the number of such blowers. The operating state of the main blower 12d may be controlled by a controller (not shown) or switched by an operator 6 (see Figure 2). In addition to the gas supply passage 12b, the gas supply device 12 of this embodiment is provided with a gas return passage 12c. The gas return passage 12c shown in Figure 1 is a passage that connects the generator 12a and the upper end of the tank 11. The lower part of the tank 11 may be provided with an opening 11b for removing sterilized granular material and a cover 11c that can open and close the opening 11b.

[0030] While granular materials are typically exposed to gas while placed in mesh bags, in this invention, due to the formation of a fluidized bed, exposure in bags is not possible. Therefore, to improve workability, the following modifications can be considered. The tank 11 may be detachably constructed so that the granular materials can be removed along with the tank 11. Alternatively, the tank 11 may be tilted to facilitate the removal of the granular materials. As an alternative configuration, a fixed tank 11 may have an inlet at the top and a discharge port at the bottom so that the processed granular materials flow out by their own weight.

[0031] The gas supply device 12 sets the gas concentration of chlorine dioxide gas supplied to the inside of the tank 11 and the supply time of chlorine dioxide gas (hereinafter referred to as "exposure time") according to the CT value. The CT value is a value that represents the sterilization effect and is generally the product of the concentration of the disinfectant and the exposure time. The CT value may be set by, for example, the operator 6, depending on the granular material to be sterilized. The gas supply device 12 continues to supply chlorine dioxide gas at the set concentration to the inside of the tank 11 for the set exposure time. The gas concentration may be a fixed value according to the performance of the gas supply device 12, or it may be a variable value set by the operator 6 operating the control unit 40 described later. The exposure time is a value that is determined once the CT value and gas concentration are determined, but the exposure time may be set before the gas concentration, and the gas concentration may be set based on the CT value and exposure time. Also, since the effect of chlorine dioxide gas depends on humidity, it may have a function to automatically adjust the exposure time according to the detected humidity. This can increase the sterilization efficiency. Similarly, it may be automatically adjusted based on temperature, or a combination of both may be used.

[0032] The sterilization apparatus 10 of this embodiment further includes a decomposition apparatus 13 that takes in gas from inside the tank 11 and decomposes chlorine dioxide gas. The decomposition apparatus 13 is a device for decomposing chlorine dioxide gas (residual gas) remaining inside the tank 11 before removing the sterilized granular material from the tank 11. The decomposition apparatus 13 shown in Figure 1 has a decomposition filter 13a, a branch passage 13b branched from the gas supply passage 12b and the gas return passage 12c, and two switching valves 13c and 13d.

[0033] The decomposition filter 13a may be configured to include, for example, a pre-filter for capturing dust and debris, a main filter for decomposing chlorine dioxide gas (residual gas), and an after-filter for suppressing the scattering of dust and other particles from the main filter. A first switching valve 13c is installed at the upstream end of the branching path 13b (the branching point from the gas supply path 12b), and a second switching valve 13d is installed at the downstream end of the branching path 13b (the junction with the gas return path 12c).

[0034] Each of the switching valves 13c and 13d switches the gas flow path from the flow path through the generator 12a to the branch path 13b only during the decomposition process in which the decomposition device 13 is used. Also, during the decomposition process in which the decomposition device 13 is used, the main blower 12d is operated to guide the gas inside the tank 11 to the decomposition filter 13a. The switching valves 13c and 13d may be controlled by a controller or switched by the operator 6. In the decomposition by the decomposition device 13, it is preferable that a fluidized bed is formed, similar to the sterilization process. This can increase the decomposition efficiency. The decomposition device 13 may be configured with well-known configurations such as those described in Japanese Patent No. 6527277 and Japanese Patent No. 6835904.

[0035] [2. Sterilization equipment] Next, the sterilization equipment 1 will be explained using Figure 2. The sterilization equipment 1 is equipment (for buildings, facilities, workplaces, etc.) for safely sterilizing granular materials to be sterilized using chlorine dioxide gas. As shown in Figure 2, the sterilization equipment 1 comprises a sterilization device 10', a sterilization area 2, a barrier area 3, and a work area 4.

[0036] The sterilization device 10' is equipped with at least a tank 11' and a gas supply device 12', and, like the sterilization device 10 described above, is a device that sterilizes granular material contained inside the tank 11' by flowing it with chlorine dioxide gas. This sterilization device 10' is equipped with the tank 11', gas supply device 12', decomposition device 13', final decomposition device 14, and concentration meter 15, which will be described later.

[0037] [2-1. Sterilization Area] The sterilization area 2 is a sealed processing chamber with an airtight door 20 that can be opened and closed. At least one tank 11' of the sterilization device 10' is located in the sterilization area 2. In the sterilization device 10' shown in Figure 2, as described above, chlorine dioxide gas fills not only the inside of the tank 11' but also the sterilization area 2 in which the tank 11' is installed. That is, in this sterilization equipment 1, chlorine dioxide gas that has filled the sterilization area 2 is sent into the inside of the tank 11' from below, sterilizing the granular material inside the tank 11' while causing it to flow, similar to the sterilization device 10 shown in Figure 1. The top surface of the tank 11' is open, and the above-mentioned mounting surface 11a is provided at the bottom of the tank 11', with the lower part (bottom end) having a smaller cross-sectional area. Note that when the sterilization area 2 is filled with chlorine dioxide gas, gas is also present inside the tank 11'. However, during the sterilization process (sterilization process that implements the blow-out exposure method), the above flow is generated and causes the granular material to flow.

[0038] In addition to the tank 11', the sterilization area 2 may also contain a humidifier 21, a temperature sensor 22, and a humidity sensor 23. The humidifier 21 is a device that humidifies the air in the sterilization area 2. The temperature sensor 22 detects the temperature in the sterilization area 2, and the humidity sensor 23 detects the humidity in the sterilization area 2. The humidifier 21 may have a function (control board or control device) to automatically adjust the amount of humidification according to the humidity detected by the humidity sensor 23, or it may simply continue to humidify at an appropriate amount. The information detected by the temperature sensor 22 and humidity sensor 23 may be used by the controller or displayed on the display of the operation unit 40, which will be described later. Alternatively, a thermometer / hygrometer that detects both temperature and humidity may be provided instead of the temperature sensor 22 and humidity sensor 23.

[0039] [2-2. Barrier Area] Barrier area 3 is an equipment room configured to be sealed, and has an airtight door 30 that can be opened and closed. Barrier area 3 encompasses sterilization area 2 and is a room for completely separating sterilization area 2 and work area 4, at least until the final decomposition process described later is completed. In this embodiment, barrier area 3 is equipped with a gas supply device 12' and a decomposition device 13', as well as a part of the final decomposition device 14, a concentration meter 15, an air conditioner 31, an air supply passage 32, a decomposition device 33 for barrier area 3, and a concentration meter 34. These will be described in order below.

[0040] The gas supply device 12' shown in Figure 2 is a device that supplies chlorine dioxide gas into the tank 11' from below, similar to the gas supply device 12 shown in Figure 1. However, the gas supply device 12' in Figure 2 has a circulation path 12e and a sub-blower 12f in addition to the generator 12a, gas supply path 12b, gas return path 12c, and main blower 12d described above. The gas supply path 12b is a flow path that connects the generator 12a to the sterilization area 2, and the gas return path 12c is a flow path that connects the generator 12a to the sterilization area 2. The main blower 12d is interposed, for example, on the gas supply path 12b. The chlorine dioxide gas generated in the generator 12a is supplied into the sterilization area 2 through the gas supply path 12b. The gas containing chlorine dioxide gas in the sterilization area 2 returns to the generator 12a through the gas return path 12c. The main blower 12d generates this gas flow.

[0041] The circulation path 12e is a flow path for supplying chlorine dioxide gas from the sterilization area 2 into the tank 11' from below. One end of the circulation path 12e is connected to any position in the sterilization area 2. The other end of the circulation path 12e is mounted above the mounting surface 11a of the tank 11', facing upward (in a direction that allows chlorine dioxide gas to be blown into the tank 11' from below). The sub-blower 12f is interposed on the circulation path 12e and generates a flow of chlorine dioxide gas within the circulation path 12e. The sub-blower 12f may be a simple fan or a pressure pump, and its number is not limited to one. The operating state of the sub-blower 12f may be controlled by a controller or switched by the operator 6. The above blowing speed is achieved by the sub-blower 12f. Note that the gas supply path 12b and main blower 12d may be used instead of the circulation path 12e and sub-blower 12f. In this case, the circulation path 12e and the sub-blower 12f are unnecessary.

[0042] The decomposition device 13' shown in Figure 2 is similar to the decomposition device 13 shown in Figure 1 in that it takes in gas from inside the tank 11' and decomposes chlorine dioxide gas. However, the decomposition device 13' in Figure 2 takes in gas from within the sterilization area 2 as well as gas from inside the tank 11', and is provided independently of the gas supply device 12'. This decomposition device 13' includes the decomposition filter 13a described above, an air supply passage 13e, an air return passage 13f, a blower 13g, a first damper 13h, and a second damper 13j. The air supply passage 13e is a passage that connects the decomposition filter 13a to the sterilization area 2, and the air return passage 13f is a passage that connects the decomposition filter 13a to the sterilization area 2.

[0043] The blower 13g is installed, for example, on the air supply passage 13e. The blower 13g may be a simple fan or a pumping device, and there is no limit to the number of blowers. The first damper 13h is installed on the air supply passage 13e (for example, at its downstream end), and the second damper 13j is installed on the air return passage 13f (for example, at its upstream end). Each damper 13h and 13j is an air flow control valve and is opened only during the disassembly process in which the disassembly device 13' is used. The operating state of the blower 13g and the state of each damper 13h and 13j may be controlled by a controller or switched by the operator 6.

[0044] The decomposition device 13' decomposes the chlorine dioxide gas (residual gas) remaining in the sterilization area 2 before removing the sterilized granular material from the tank 11' in the sterilization area 2. In the decomposition process in which the decomposition device 13' is used, the first damper 13h opens the air supply passage 13e and the second damper 13j opens the air return passage 13f, and the blower 13g is activated, guiding the gas in the sterilization area 2 to the decomposition filter 13a, and after passing through the decomposition filter 13a, it returns to the sterilization area 2.

[0045] The final decomposition device 14 is a device that, after the decomposition process of residual gas by the decomposition device 13', supplies air into the sterilization area 2, takes in the gas in the sterilization area 2, further decomposes the chlorine dioxide gas, and discharges it outdoors 5. The final decomposition device 14 operates in place of the decomposition device 13' when, for example, the decomposition process by the decomposition device 13' has reached a predetermined time or the gas concentration in the sterilization area 2 has fallen below a predetermined value. In other words, in the final decomposition process in which the final decomposition device 14 is used, the decomposition device 13' is stopped.

[0046] The final decomposition device 14 includes a decomposition filter 14a, a decomposition air supply passage 14b, a decomposition exhaust passage 14c, an exhaust fan 14d, a third damper 14e, a fourth damper 14f, and a medium-efficiency filter 14g. The decomposition filter 14a has a configuration similar to, for example, the decomposition filter 13a described above. The decomposition air supply passage 14b is a flow path connecting the work area 4 and the sterilization area 2, and the decomposition exhaust passage 14c is a flow path connecting the sterilization area 2 and the outdoors 5 (or the exhaust passage 42 connected to the outdoors 5).

[0047] The exhaust fan 14d is interposed on the decomposition exhaust passage 14c and may be a simple fan or a pressure pump, and its number is not limited to one. The third damper 14e is interposed on the decomposition supply passage 14b (for example, at its downstream end), and the fourth damper 14f is interposed on the decomposition exhaust passage 14c (for example, at its upstream end). Each damper 14e, 14f is a backflow prevention damper and is opened only during the final decomposition process in which the final decomposition device 14 is used, allowing only one-way flow. The medium-efficiency filter 14g is interposed on the decomposition supply passage 14b, upstream of the third damper 14e, to remove dust, debris, etc., from the sterilized granular material. The operating state of the exhaust fan 14d may be controlled by a controller or switched by the operator 6.

[0048] In the example shown in Figure 2, a portion of the decomposition air supply passage 14b, a portion of the decomposition exhaust passage 14c, and dampers 14e and 14f are located within the barrier area 3, while the decomposition filter 14a, the rest of the decomposition air supply passage 14b, the rest of the decomposition exhaust passage 14c, and the exhaust blower 14d are located within the work area 4. However, the arrangement is not limited to this, and for example, the decomposition filter 14a and the exhaust blower 14d may be located within the barrier area 3. Furthermore, a filter to capture dust and debris from the intake air may be interposed on the decomposition air supply passage 14b.

[0049] The concentration meter 15 is a device that combines the functions of diluting the gas concentration in the sterilization area 2 and measuring the gas concentration in the sterilization area 2. The concentration meter 15 has a circulation path 15a, a concentration meter 15b, and a pump 15c. The circulation path 15a has both ends connected to any position in the sterilization area 2 and is a flow path through which gas in the sterilization area 2 can circulate. The concentration meter 15b and the pump 15c are interposed on the circulation path 15a.

[0050] The concentration meter 15b detects the concentration of the gas flowing through the circulation path 15a. The concentration detected here (gas concentration in the sterilization area 2) may be used by the controller or displayed on the display of the operation unit 40. The pump 15c is a pressurized device that circulates gas through the circulation path 15a. The operating state of the pump 15c may be controlled by the controller or switched by the operator 6. A blower (fan) may be used instead of the pump 15c.

[0051] The air conditioner 31 is an example of a temperature control device that adjusts the temperature inside the barrier area 3. By adjusting the temperature inside the barrier area 3, the temperature inside the sterilization area 2 is indirectly adjusted. Alternatively, a temperature control device may be installed in the sterilization area 2 instead of the air conditioner 31. The air supply passage 32 connects the work area 4 and the barrier area 3, and is a flow path that takes in air from the work area 4 into the barrier area 3. A backflow prevention damper 32a is interposed in the air supply passage 32. This limits the direction of gas flow to only one direction, from the work area 4 to the barrier area 3.

[0052] The decomposition device 33 for barrier area 3 is a device for decomposing chlorine dioxide gas in barrier area 3. This decomposition device 33 takes in gas from within barrier area 3 and decomposes any chlorine dioxide gas that may be present within barrier area 3. This decomposition device 33 may operate continuously while the sterilization device 10' is operating, or it may operate after the sterilization process by the sterilization device 10' is completed (for example, while the decomposition device 13' is operating), or it may operate depending on the concentration of chlorine dioxide gas in barrier area 3 (for example, only in emergencies). The decomposition device 33 may be configured, like the decomposition devices 13 and 13' described above, to include a flow path 33b through which gas flows, a decomposition filter 33a interposed on this flow path 33b, and a blower (not shown) that generates the gas flow.

[0053] The concentration meter 34 detects the concentration of chlorine dioxide gas in the barrier area 3. The concentration detected here (gas concentration in barrier area 3) may be used by the controller or displayed on the display of the operation unit 40. For example, the controller may be configured to constantly monitor the gas concentration in barrier area 3. Alternatively, for example, the controller may activate the decomposition device 33 for barrier area 3 when the gas concentration in barrier area 3 is above a predetermined concentration.

[0054] [2-3. Work Area] Work area 4 is a workspace where the control unit 40 for the sterilization device 10' is located. Work area 4 encompasses barrier area 3 and is the room where the worker 6 operates the control unit 40. Work area 4 is equipped with a standard air conditioning and ventilation system. In this embodiment, work area 4 is equipped with the control unit 40, a lamp 41, an exhaust passage 42, and a concentration meter 44.

[0055] The operation unit 40 is configured, for example, with a display and a touch panel. The display is a device that shows the status of the sterilization device 10', the progress of the sterilization process, the conditions inside the sterilization area 2 (temperature, humidity, concentration), and the operating status of various devices inside the sterilization area 2 and the barrier area 3. The touch panel is an input device for detecting input operations (touch, pinch, swipe, etc.) by the operator 6 on the surface of the display. The operation unit 40 may be provided as a touch panel type display in which the display and the touch panel are integrated. The operator 6 may, for example, operate the touch panel according to the content displayed on the display to start the sterilization process or switch the operating status of various devices.

[0056] Lamp 41 is a means of notifying the worker 6. Examples of lamps 41 include an operation lamp indicating that various equipment in the sterilization area 2 and barrier area 3 is operating, a stop lamp indicating that all equipment has stopped operating, and a warning lamp prohibiting entry to barrier area 3. The type, number, and arrangement of lamps 41 are not particularly limited. For example, the number and arrangement of lamps 41 may be set according to the size of the sterilization equipment 1 and the number of doors 30.

[0057] The exhaust passage 42 connects the barrier area 3 to the outdoors 5 and is a flow path for discharging gas from the barrier area 3 to the outdoors 5. A decomposition filter 42a and a blower 42b are interposed in the exhaust passage 42. The decomposition filter 42a has a configuration similar to, for example, the decomposition filter 13a described above, and removes chlorine dioxide gas contained in the gas flowing through the exhaust passage 42 by decomposing it. The blower 42b is a fan or pumping device that generates a unidirectional flow in the exhaust passage 42. The number of blowers 42b is not limited to one. It is preferable that the blower 42b is in a continuously operating state when the sterilization equipment 1 is in use.

[0058] The concentration meter 44 detects the concentration of chlorine dioxide gas in the work area 4. The concentration detected here (gas concentration in work area 4) may be used by the controller or displayed on the display of the operation unit 40. For example, the controller may be configured to constantly monitor the gas concentration in work area 4.

[0059] [2-4. Others] Outdoor area 5 is outside the sterilization equipment 1. An outlet 42c of the exhaust passage 42 is located on the outer wall of the sterilization equipment 1 (the wall that partitions the work area 4). A concentration meter 54 for detecting the concentration of chlorine dioxide gas is located near this outlet 42c. The concentration detected here (the gas concentration near the outlet 42c in outdoor area 5) may be used by the controller or displayed on the display of the operation unit 40. For example, the controller may be configured to constantly monitor the gas concentration near the outlet 42c in outdoor area 5.

[0060] If the controller is configured to monitor each gas concentration (gas concentration in barrier area 3, gas concentration in work area 4, and gas concentration near outlet 42c in outdoor area 5), ​​the operation of the sterilization device 10' may be forcibly stopped if any of the gas concentrations exceeds the control value. In addition, each door 20, 30 may be equipped with a door lock (not shown) to prevent accidental opening. Note that there may be one or more doors 20, 30. Furthermore, emergency stop buttons (not shown) may be placed in each area 2, 3, and 4, and a lamp similar to lamp 41 or a lamp with an alarm speaker may be placed in barrier area 3.

[0061] It is desirable to adjust the exhaust airflow by controlling exhaust fans and dampers so that the outdoor area 5 is at normal pressure, the work area 4 is at negative pressure, the barrier area 3 is at a lower negative pressure than the work area 4, and the sterilization area 2 is at a lower negative pressure than the barrier area 3. This protects the workers 6 and prevents gas leakage to the outside. Since the top of the tank 11' is open, the pressure inside the sterilization area 2 and the tank 11' are the same. If a pressure difference is created between the tank 11' and the sterilization area 2, the formation of the fluidized bed inside the tank 11' may become unstable, but this method allows for the formation of a relatively stable fluidized bed.

[0062] The sterilization device 10' described above preferably has an interlock. For example, it is preferable that the sterilization device 10' does not operate unless the locked state of each door 20, 30, the detected values ​​of each concentration meter 34, 44, 54, and the operating state of the various devices in the sterilization area 2 and barrier area 3 each meet predetermined conditions. This ensures a higher level of safety.

[0063] [3. Sterilization method, method for producing sterilized granular material] Figure 3 is a flowchart showing the sterilization method according to this embodiment, as well as a flowchart showing the method for producing sterilized granular material according to this embodiment. This sterilization method and manufacturing method can be carried out using either the sterilization apparatus 10, 10' shown in Figures 1 and 2. Steps S2 to S10 may be controlled by a controller, or the operator 6 may operate the control unit 40 to proceed to the next step.

[0064] In step S1, granular material to be sterilized is placed (filled) inside the tanks 11 and 11'. At this time, preparations for the operation of the sterilization devices 10 and 10' are also carried out. For the sterilization device 10 shown in Figure 1, preparations include, for example, setting the gas concentration and exposure time of the gas supply device 12, closing the lid on the top of the tank 11 and connecting the gas return path 12c. For the sterilization device 10' shown in Figure 2, preparations include, for example, setting the gas concentration and exposure time of the gas supply device 12', preparing the humidifier 21, and closing and locking the door 20.

[0065] In the subsequent step S2, chlorine dioxide gas is supplied to the inside of tanks 11 and 11' from below, and the granular material inside tanks 11 and 11' is sterilized while being fluidized by the blowing out of chlorine dioxide gas (implementation of a sterilization process by blowing exposure). In this sterilization process, the blowing speed of chlorine dioxide gas into tanks 11 and 11' is set to be greater than or equal to the minimum fluidization speed and less than the slugging start speed. In the case of the sterilization apparatus 10 in Figure 1, the above blowing speed is achieved by the main blower 12d, and in the case of the sterilization apparatus 10' in Figure 2, the above blowing speed is achieved by the sub blower 12f.

[0066] In step S3, it is determined whether the preset chlorine dioxide gas concentration has been reached and whether the exposure time (predetermined time) has elapsed. If the chlorine dioxide gas concentration has not reached the predetermined concentration, or if the elapsed time since the start of the sterilization process is less than the exposure time, the process returns to step S2 and the sterilization process continues. This sterilizes the granular material inside tanks 11, 11' for a predetermined time while it is being fluidized by the blowing out of chlorine dioxide gas. When the chlorine dioxide gas concentration reaches the predetermined concentration and the elapsed time since the start of the sterilization process reaches the exposure time, the process proceeds to step S4. In step S4, the supply of gas from the gas supply device 12 is stopped.

[0067] Next, in step S5, the decomposition process is carried out by the decomposition devices 13 and 13'. In the sterilization device 10 shown in Figure 1, the first switching valve 13c and the second switching valve 13d switch the gas flow path from the flow path through the generator 12a to the branching path 13b. Then, when the main blower 12d is activated, the gas in the tank 11 circulates through part of the gas return path 12c, the branching path 13b, and part of the gas supply path 12b, and the chlorine dioxide gas contained in the gas is decomposed in the decomposition filter 13a. Also, in the sterilization device 10' shown in Figure 2, the two dampers 13h and 13j are opened and the blower 13g is activated. As a result, the gas in the sterilization area 2 circulates through the air supply path 13e and the air return path 13f, and the chlorine dioxide gas contained in the gas is decomposed in the decomposition filter 13a.

[0068] In step S6, it is determined whether the termination conditions for the decomposition process have been met. Termination conditions include, for example, that the execution time for the decomposition process has reached a predetermined time, or that the gas concentration inside tanks 11 and 11' or the gas concentration in the sterilization area 2 has fallen below a predetermined value. The decomposition process in step S5 continues until the termination conditions are met, at which point the process proceeds to step S7. In step S7, the operation of the decomposition devices 13 and 13' is stopped. In the case of the sterilization device 10 shown in Figure 1, once this process is complete, the cover 11c of tank 11 can be opened and the sterilized granular material removed from the opening 11b (step S11).

[0069] In the case of the sterilization equipment 1 shown in Figure 2, steps S8 to S10 are then performed. In step S8, the final decomposition process is carried out by the final decomposition device 14. Specifically, the two dampers 14e and 14f are opened and the exhaust fan 14d is activated. As a result, air from the work area 4 flows into the sterilization area 2 through the decomposition air supply passage 14b, and gas from the sterilization area 2 flows through the decomposition exhaust passage 14c. In the decomposition filter 14a, any chlorine dioxide gas that may be contained in the gas is decomposed and discharged to the outdoors 5.

[0070] In step S9, it is determined whether the termination conditions for the final decomposition process have been met. These termination conditions may be set based on the execution time of the final decomposition process (the final decomposition time has elapsed) or the gas concentration in the sterilization area 2 (the concentration has fallen below a predetermined level). The final decomposition process in step S8 continues until the termination conditions in step S9 are met, at which point the process proceeds to step S10. In step S10, the operation of the final decomposition apparatus 14 is stopped. Finally, in step S11, the granular material is removed from the tank 11'. This produces sterilized granular material.

[0071] [4. Action, Effects] Figure 4 is a graph illustrating the operation of the sterilization apparatus 10, 10' and sterilization method according to the embodiment, and shows an example of test results for CT values ​​and the number of orders of magnitude of bacterial count reduction. In Figure 4, the average number of bacteria at 15 points in the granular material layer (the layer formed by the granular material contained in the tank) is used as the bacterial count for each CT value. The horizontal axis of the graph is the CT value, and the vertical axis is the number of orders of magnitude of bacterial count reduction. In this invention, the CT value is set to 1.0 when the number of orders of magnitude of bacterial count reduction is -5.0 or less. Also, circles in the graph indicate the case when the blow-out exposure method (of this invention) described above is performed, and triangles in the graph indicate the case when the suction exposure method is performed.

[0072] The suction exposure method referred to here is a method in which granular material to be sterilized is placed (filled) in an exposure tank (for example, a tank similar to tank 11 above), and gas is drawn in from the bottom of the exposure tank or pushed in from the top of the exposure tank, allowing the gas to pass through the gaps in the granular material layer. Although the blow-out exposure method and the suction exposure method differ significantly in the direction of gas supply, they both use chlorine dioxide gas for sterilization, and both involve not only filling the container with chlorine dioxide gas but also continuously flowing the gas.

[0073] As shown in Fig. 4, from the state where the CT value is 0 at the start of the sterilization treatment to about 0.4 of the CT value, regardless of the method, as the CT value increases, the number of bacteria decreases, and there is almost no difference in the number of decreasing digits. This is because, regardless of the method, for some time after the start of the sterilization treatment, the bacteria attached to the particulate matter located at the position where the gas is likely to come into contact are killed.

[0074] However, when the CT value further increases, in the suction exposure method, at most, the number of bacteria decreases only to about 10 -4 [CFU] per 1 [g] of particulate matter. This is because, in the case of the suction exposure method, the packing density of the particulate matter layer inside the exposure tank is not uniform, resulting in uneven pressure loss in the particulate matter layer. As a result, a part where the gas easily passes through (the part that becomes the gas flow path) and a part where the gas hardly passes through (the part outside the gas flow path) are formed in the particulate matter layer, and it is considered that unevenness in gas concentration occurs in the particulate matter layer. In addition, when the particulate matter layer accommodated in the exposure tank is thick or the particulate matter forms a lump, it is considered that one of the factors is that there is a possibility that the gas does not reach sufficiently inside the layer or inside the lump (the part where the particulate matters continue to contact each other).

[0075] On the other hand, in the above-described blowing exposure method, it is possible to reduce the number of bacteria to about 10 -6 [CFU] per 1 [g] of particulate matter at most. This is because, in the above-described blowing exposure method, the particulate matter is accommodated inside the tanks 11, 11′, chlorine dioxide gas is supplied from below into the inside of the tanks 11, 11′, and the particulate matter is sterilized while being fluidized by the blowing of the gas, so that unevenness in gas concentration does not occur in the entire particulate matter. In addition, since the particulate matter is in a fluidized state, a situation where it does not move as a lump is avoided, there is no part where the particulate matters continue to contact each other, and the gas reaches sufficiently inside the fluidized bed.

[0076] As described above, the sterilization apparatus 10, 10' and sterilization method allow chlorine dioxide gas to be blown into the tanks 11, 11' from below, causing the granular material to flow and ensuring uniform exposure of the granular material to the chlorine dioxide gas. This ensures uniform sterilization of all granular material. Furthermore, the sterilization apparatus 10, 10' and sterilization method allow for faster sterilization compared to the suction exposure method. This is because, with the suction exposure method, uneven gas concentration occurs within the granular material layer, requiring the exposure time to be extended to compensate for areas with lower gas concentrations. However, with the blow-out exposure method, uneven gas concentration does not occur, eliminating the need for such adjustments. Moreover, since the sterilization apparatus 10, 10' and sterilization method use chlorine dioxide gas for sterilization, sterilization and disinfection can be performed while the material is dry. Therefore, the wetting and drying process is unnecessary, further reducing processing time and lowering energy consumption compared to the dry heat treatment method.

[0077] In the sterilization apparatus 10,10' described above, the cylindrical tanks 11,11' have a mesh-like mounting surface 11a, and the gas supply apparatus 12,12' has a generator 12a and a gas supply passage 12b. As a result, chlorine dioxide gas can be generated in the sterilization apparatus 10,10', and by supplying this chlorine dioxide gas into the cylindrical tanks 11,11' from below, the flow of granular material can be promoted. Therefore, the sterilization process can be completed more evenly and in a shorter time.

[0078] The sterilization apparatus 10,10′ described above is further equipped with decomposition devices 13,13′ that take in the gas inside the tanks 11,11′ and decompose the chlorine dioxide gas, so that the chlorine dioxide gas can be decomposed after the sterilization process is completed. This enhances safety. Furthermore, by setting the rate at which chlorine dioxide gas is blown into the tanks 11 and 11' to be greater than or equal to the minimum fluidization rate and less than the slugging initiation rate, the flow of granular material can be ensured, allowing the sterilization process to be completed evenly and in a short time.

[0079] The sterilization equipment 1 described above includes a sterilization device 10', a sealable sterilization area 2 where a tank 11' is located, a sealable barrier area 3 encompassing the sterilization area 2, and a work area 4 encompassing the barrier area 3. The sterilization area 2 is filled with chlorine dioxide gas, the work area 4 is where the worker 6 is located, and the barrier area 3 is located between these areas 2 and 4. Therefore, with the sterilization equipment 1 described above, all granular materials can be sterilized evenly while ensuring safety by reliably preventing leakage of chlorine dioxide gas, and the sterilization process can be completed in a short time.

[0080] Furthermore, the sterilization equipment 1 described above is equipped with an air supply passage 32 interposed with a backflow prevention damper 32a, a decomposition device 33 for the barrier area 3, a concentration meter 34 for detecting the concentration in the barrier area 3, and an exhaust passage 42 for discharging the gas in the barrier area 3 to the outdoors 5. With this configuration, even if chlorine dioxide gas is present in the barrier area 3, its concentration can be monitored and it can be appropriately decomposed, thereby ensuring the safety of the workers 6.

[0081] Furthermore, in the sterilization equipment 1 described above, a humidifier 21, a temperature sensor 22, and a humidity sensor 23 are installed in the sterilization area 2, and an air conditioner 31 is installed in the barrier area 3. Therefore, based on the detection results of the temperature sensor 22 and the humidity sensor 23, the temperature and humidity in the sterilization area 2 can be adjusted to a state suitable for sterilization. This makes it possible to shorten the sterilization process time and improve the sterilization performance.

[0082] Furthermore, granular material to be sterilized is placed inside tanks 11 and 11', chlorine dioxide gas is supplied to the inside of tanks 11 and 11' from below, and the granular material inside tanks 11 and 11' is sterilized for a predetermined time while being fluidized by the blowing out of chlorine dioxide gas. After that, the granular material is removed from tanks 11 and 11', thereby producing sterilized granular material. According to this manufacturing method, sterilized granular material can be obtained evenly in a short time while suppressing energy consumption.

[0083] [5. Others] The sterilization apparatus 10, 10', sterilization equipment 1, sterilization method, and method for producing sterilized granular material described above are all examples and are not limited to the configurations and methods described above. For example, the shape of the tank may be a cylindrical shape other than a cylindrical shape, and the part for removing the sterilized granular material may be located somewhere other than the bottom of the tank. Also, the decomposition devices 13 and 13' may be omitted from the sterilization devices 10 and 10', and the final decomposition device 14 and concentration meter 15 may be omitted from the sterilization equipment 1. The various equipment and flow paths arranged in the sterilization area 2, barrier area 3, and work area 4 are also examples and may be changed as appropriate.

[0084] The above-mentioned methods for setting the CT value, gas concentration, and exposure time are all examples. For example, if the granular material is not an object that oxidizes (corrodes), setting the maximum CT value will be sufficient for sterilization. Also, while increasing the gas concentration can shorten the exposure time, a longer exposure time is generally better for sterilization. Therefore, appropriate values ​​can be set by balancing the gas concentration, exposure time, and sterilization effect.

[0085] Although the sterilization devices 10 and 10' described above are fixed, a sterilization device (continuous sterilization device) may be provided, for example, by arranging the sterilization device on a continuous moving body such as a long belt conveyor and performing sterilization as part of the line work. Furthermore, an automatic feeding device may be provided to automatically dispense granular material from a storage section where the material is to be processed, and an automatic discharge device may be provided to automatically discharge the material from tanks 11 and 11'. In addition, multiple tanks 11 and 11' may be provided and switched at each processing stage to perform batch operation. [Explanation of Symbols]

[0086] 1 Sterilization equipment 10,10′ Sterilizer 11,11′ tank 11a Placement surface section 12,12′ Gas supply device 12a Generator 12b Gas supply line (supply line) 13,13′ Decomposition equipment 2. Sterilization Area 21 Humidifier 22 Temperature Sensor 23 Humidity Sensor 3 Barrier Area 31. Air conditioner (temperature control device) 32 Air supply passage 32a Backflow prevention damper 33 Disassembly device for barrier area 34 Densitometer 4. Work Area 40 Control section 42 Exhaust passage 5 Outdoor

Claims

1. A tank for containing the granular material to be sterilized, The tank is equipped with a gas supply device that supplies chlorine dioxide gas to the inside of the tank from below, The gas supply device sterilizes the granular material inside the tank by causing it to flow through the blowing of chlorine dioxide gas. A sterilization device characterized by the following features.

2. The tank is cylindrical and has a mesh-like surface on which the granular material is placed and through which the chlorine dioxide gas flows. The gas supply device includes a generator for generating chlorine dioxide gas and a supply path for supplying the chlorine dioxide gas generated by the generator to the tank. A sterilization apparatus according to claim 1, characterized in that

3. The tank further comprises a decomposition device that takes in the gas inside the tank and decomposes the chlorine dioxide gas. A sterilization apparatus according to claim 1, characterized in that

4. The rate at which the chlorine dioxide gas is blown into the tank is greater than or equal to the minimum fluidization rate and less than the slugging initiation rate. A sterilization apparatus according to claim 1, characterized in that

5. A sterilization device according to any one of claims 1 to 4, The tank of the sterilization apparatus is located in a sealed sterilization area, A barrier area that includes the aforementioned sterilization area and can be sealed, The system includes a work area which encompasses the barrier area and where an operating unit for the sterilization device is located, and where an operator operates the operating unit. A sterilization device characterized by the following features.

6. A backflow prevention damper is interposed, and an air supply passage is provided to draw air from the work area into the barrier area, A decomposition device for a barrier area that decomposes the chlorine dioxide gas within the barrier area, A concentration meter for detecting the concentration of chlorine dioxide gas within the barrier area, The barrier area includes an exhaust passage for discharging gas from within the barrier area to the outside. The sterilization equipment according to claim 5, characterized in that it is a sterilization apparatus.

7. A humidifier placed in the aforementioned sterilization area, A temperature control device located in the sterilization area or the barrier area, A temperature sensor for detecting the temperature within the sterilization area, The system includes a humidity sensor that detects the humidity within the sterilization area. The sterilization equipment according to claim 5, characterized in that it is a sterilization apparatus.

8. The granular material to be sterilized is placed inside the tank, Chlorine dioxide gas is supplied into the tank from below, and the granular material inside the tank is sterilized while being fluidized by the blowing out of the chlorine dioxide gas. A sterilization method characterized by the following features.

9. The rate at which the chlorine dioxide gas is blown into the tank is greater than or equal to the minimum fluidization rate and less than the slugging initiation rate. The sterilization method according to claim 8, characterized in that

10. The granular material to be sterilized is placed inside the tank, Chlorine dioxide gas is supplied into the tank from below, and the granular material inside the tank is sterilized for a predetermined time while being moved by the blowing out of the chlorine dioxide gas. Then, the granular material is removed from the tank. A method for producing sterilized granular material, characterized by the following:

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