Agricultural product sterilization system using low-temperature atmospheric pressure plasma

Abstract

The present invention relates to an agricultural product sterilization system using low-temperature atmospheric pressure plasma, comprising: a transfer unit (600) that transfers agricultural products to be sterilized; a tunnel-type housing (700) formed on an upper end of the transfer unit (600) and having one end into which the agricultural products to be sterilized are introduced and the other end from which the sterilized agricultural products are discharged; and an ozone injection port (110) that supplies ozone to the inside of the tunnel-type housing (700).

Description

Agricultural product sterilization system using low-temperature atmospheric pressure plasma

[0001] The present invention relates to an agricultural product sterilization system using low-temperature atmospheric pressure plasma, and more specifically, to an agricultural product sterilization system capable of effectively sterilizing agricultural products such as fruits or vegetables using substances such as ozone generated by a low-temperature atmospheric pressure plasma device without using water or chemicals.

[0002] To safely store and maintain freshness of agricultural products such as fruits and vegetables, various methods have been proposed to sterilize their surfaces. Common sterilization methods include UV sterilization, chemical treatment, and heating. While heating can extend the shelf life of agricultural products by inhibiting microbial growth, its use is limited due to the inability of many agricultural products to be heated. Even for those that can be heated, negative effects such as deterioration of the fruit's natural components and destruction of nutrients are often observed. Chemical treatment uses liquid sterilizing and disinfecting agents to sterilize the surface of agricultural products. These methods typically involve spraying chlorine-based agents, electrolyzed water (hypochlorous acid), chlorine dioxide, ozone, and alcohol. However, these methods directly spray moisture onto the surface of agricultural products, making them difficult to use on fruits that are sensitive to moisture. UV sterilization offers the advantages of being relatively simple and leaving no residue after treatment, but it is difficult to sterilize shaded areas of the product.

[0003] FIGS. 1 and 2 relate to a low-temperature atmospheric pressure plasma generator applied for and registered by the applicant of the present invention, in which electric conductors (134) and ceramic tubes (136) are arranged alternately in parallel, and when power is supplied, plasma is generated by discharge between the electric conductors (134) and the ceramic tubes (136), generating ozone radicals, which are then mixed with air to generate ozone. FIG. 2 illustrates a means for supplying power to the plasma ozone generator, which may include an AC power source, an AC rectifier circuit for rectifying AC power and converting it into DC power, a drive circuit (143) for amplifying current / voltage to generate output, a resonance circuit (145), etc. The active species (ozone, hydrogen peroxide, nitrogen oxide, etc.) generated by such a low-temperature atmospheric pressure plasma generator have a strong sterilizing power that can remove microorganisms existing on the surface of agricultural products, while not significantly affecting the flesh quality or components of the agricultural products themselves.

[0004] Although such low-temperature atmospheric pressure plasma materials are effective in sterilizing agricultural products, they are only being used experimentally or on a small scale, and a system capable of effectively treating large quantities of agricultural products using atmospheric pressure plasma has not been introduced.

[0005] The present invention is intended to solve the problems of the prior art described above, and aims to provide an agricultural product sterilization system capable of continuously sterilizing a large quantity of agricultural products without having the problems of harmful effects on the human body or deterioration of marketability that conventional sterilization methods have.

[0006] The present invention relates to an agricultural product sterilization system using low-temperature atmospheric pressure plasma, comprising: a transport section (600) for transporting agricultural products to be sterilized; a tunnel-shaped housing (700) formed at the upper end of the transport section (600), wherein agricultural products to be sterilized enter through one end and agricultural products that have been sterilized exit through the other end; and an ozone injection port (110) for supplying ozone into the interior of the tunnel-shaped housing (700).

[0007] The inside of the above tunnel-shaped housing (700) includes an ozone concentration injection area (120) where ozone is supplied by an ozone injection port (110); an ozone circulation area (200) where ozone is circulated inside the tunnel-shaped housing (700) by a circulation air injection port (210); and an ozone blocking area (300) where outside air is introduced into the inside of the tunnel-shaped housing (700) by an outside air injection port (310). The tunnel-shaped housing (700) is characterized in that the ozone blocking area (300), the ozone circulation area (200), the ozone concentration injection area (100), the ozone circulation area (200), and the ozone blocking area (300) are formed in this order based on the direction of movement of agricultural products.

[0008] Ozone generated in the above ozone generating unit (410) is injected into the ozone concentration injection area (100) through the ozone injection port (110), and the air within the ozone concentration injection area (100) can be supplied back to the ozone generating unit (410) by the first blower (421).

[0009] The above ozone generator (410) may include a low-temperature atmospheric pressure plasma generator (411).

[0010] The air within the above ozone circulation area (200) can be discharged through the exhaust pipe and then supplied back to the ozone circulation area (200) through the circulation air injection port (210) by the second blower (422).

[0011] External air is supplied to the ozone blocking area (300) through the external air injection (310) by the third blower (423), but the air within the ozone blocking area (300) can escape to the ozone depletion facility (430).

[0012] The agricultural product sterilization system using low-temperature atmospheric pressure plasma according to the present invention continuously sterilizes a large amount of agricultural products using ozone or ozone water containing dissolved ozone, thereby preventing the occurrence of a situation where toxic substances remain on the surface of agricultural products.

[0013] Furthermore, continuous sterilization is performed during the process of passing a large quantity of agricultural products through a tunnel-type housing by a conveyor or other means of transportation, but by controlling the ozone concentration distribution within the tunnel-type housing, the situation of ozone within the tunnel-type housing leaking outside the tunnel-type housing can be effectively prevented.

[0014] Figures 1 and 2 illustrate a low-temperature atmospheric pressure plasma generator invented and patented by the inventor of the present invention.

[0015] Figure 3 illustrates the overall configuration of an agricultural product sterilization system according to one embodiment of the present invention.

[0016] Figures 4 and 5 illustrate cages for transporting agricultural products.

[0017] Figure 6 illustrates a cage being placed on a conveyor and moving.

[0018] Figure 7 shows a cross-section of an ozone concentration injection area.

[0019] FIG. 8 illustrates a low-temperature atmospheric pressure plasma generator according to one embodiment of the present invention.

[0020] Figure 9 shows a cross-section of the ozone circulation region.

[0021] Figure 10 illustrates a cross-section of an ozone blocking area.

[0022] Figures 11 and 12 illustrate the second and third embodiments of the present invention, respectively.

[0023] Hereinafter, the overall configuration of an agricultural product sterilization system using low-temperature atmospheric pressure plasma according to the present invention will be described with reference to the drawings. Specific structural and functional descriptions presented in the embodiments of the present invention are merely illustrative for the purpose of explaining embodiments according to the concept of the present invention, and embodiments according to the concept of the present invention may be implemented in various forms. Furthermore, the present invention should not be construed as being limited to the embodiments described herein, but should be understood to include all modifications, equivalents, and substitutes included within the spirit and technical scope of the present invention.

[0024] Figure 3 illustrates an agricultural product sterilization system using low-temperature atmospheric pressure plasma according to a first embodiment of the present invention. A tunnel-shaped housing (700) with open ends is placed on the upper end of a horizontal moving means, such as a conveyor, a conveyor belt. Agricultural products to be sterilized enter one open end of the tunnel-shaped housing (700) by the conveyor belt (600) and exit through the other open end. Surface sterilization of the agricultural products occurs while they pass through the tunnel-shaped housing (700).

[0025] The space inside the tunnel-type housing (700) is divided into an ozone concentration injection area (100), an ozone circulation area (200), and an ozone blocking area (300). The ozone concentration injection area (100) is an area where ozone is sprayed by a plurality of ozone spray holes (110) installed inside the tunnel-type housing (700), and the ozone circulation area (200) is an area where ozone sprayed from the ozone spray holes (110) is circulated. Although the ozone concentration is lower than that of the ozone concentration injection area (100), it is an area where the concentration is maintained above a certain level. In addition, the ozone blocking area (300) is a part that rapidly lowers the ozone concentration to prevent ozone from escaping outside the tunnel-type housing. As illustrated in FIG. 3, the ozone blocking area (300), ozone circulation area (200), ozone concentration injection area (100), ozone circulation area (200), and ozone blocking area (300) are formed in this order based on the direction of agricultural product movement.

[0026] As agricultural products pass through the tunnel-shaped housing (700) along the conveying section (600), surface sterilization is mainly performed in the ozone concentration spraying area (100) and the ozone circulation area (200), and in the ozone blocking area (300), the ozone in the ozone circulation area (200) is prevented from leaking out of the tunnel-shaped housing (700) by the air curtain action.

[0027] Referring to FIG. 7 (section A in FIG. 3), the ozone concentrated injection area is examined, and ozone produced in the ozone generating unit (410) is supplied to the ozone concentrated injection area (100) through the ozone injection port (100). As illustrated in FIG. 6, the ozone injection port (100) is installed at the top of the tunnel-shaped housing (700) to inject ozone downward, and is also installed at the bottom of the tunnel-shaped housing (700) to inject ozone upward, thereby allowing the entire surface of agricultural products passing through it to be evenly exposed to ozone. In addition, the air within the ozone concentrated injection area (100) is discharged out of the ozone concentrated injection area (100) through the pipe and supplied back to the ozone generating unit (410) by the first blower (421). Through this configuration, the concentration of ozone supplied to the ozone concentrated injection area (100) through the ozone injection port (110) is increased to a critical level.

[0028] Inside the ozone generating unit (410), a low-temperature atmospheric pressure plasma generator (411) is provided as shown in FIG. 8. The low-temperature atmospheric pressure plasma generator (411) used here relates to a low-temperature atmospheric pressure plasma generator applied for and registered by the applicant of the present invention, and since this has been described with reference to FIG. 1 and FIG. 2 in the prior art section, a detailed description thereof will be omitted.

[0029] Referring to Fig. 9 (cross-section B in Fig. 3), the ozone circulation area (200) is examined. The air within the ozone circulation area (200) is discharged to the outside of the tunnel-shaped housing (700) through the exhaust pipe, and the discharged air is supplied back to the ozone circulation area (200) through the circulation air injection port (210) by the second blower (422). Through the above configuration, the ozone circulation area (200) maintains a state in which the ozone concentration is lower than that of the ozone concentration injection area (100), but the sterilization effect is still possible.

[0030] Preferably, a sterilizing water injection port (900) may be provided within the ozone concentration injection area (100) or the ozone circulation area (200). Sterilizing water refers to water in which ozone is dissolved. When ozone is dissolved in water, OH radicals are formed, which are known to be chemically very active and to oxidize bacteria, viruses, mold, and various harmful gases that generate odors in the air or water by chemical reactions. The decomposition speed of ozone is greatly affected by pH because it has the characteristic of being self-decomposed by OH radicals. In other words, ozone is maintained in a stable state in acidic conditions, but the decomposition speed becomes faster as the condition becomes alkaline. And ozone begins to decompose by initially formed OH radicals, and as intermediate products, it goes through the intermediate path of hydroperoxy radicals (HO2-), superoxide radicals (O2-), and ozonide radicals (O3-) to generate OH radicals. These OH radicals show stronger sterilizing effects than ozone.

[0031] Sterilizing water can be sprayed through the sterilizing water spray port (900) by dissolving ozone generated through the ozone generator (410) in water in advance, but even if ordinary water is sprayed through the sterilizing water spray port (900), the sprayed water meets ozone existing in the ozone concentration spray area (100) or ozone circulation area (200) to generate ozone water, so even if only ordinary water is sprayed, it can function as sterilizing water.

[0032] Referring to FIG. 10 (cross-section C in FIG. 3), the ozone blocking area (300) is examined. The third blower (423) draws in outside air and supplies the outside air into the ozone blocking area (300) through the outside air injection port (310). The air injected through the outside air injection port (310) acts as an air curtain that prevents ozone existing in the ozone circulation area (200) from escaping outside the tunnel-shaped housing (700), while lowering the concentration of ozone in the air. The air in the ozone blocking area (300) with the ozone concentration lowered in this way moves to the ozone deoxidation facility, where the residual ozone is removed, and then discharged outside the system. Through the above configuration, a high concentration of ozone exists in the ozone concentration injection area (100) formed in the central portion of the tunnel-shaped housing (700), a lower concentration of ozone exists in the ozone circulation area (200), and the concentration of ozone in the ozone blocking area (300) decreases rapidly.

[0033] In one embodiment of the present invention, as illustrated in FIG. 4, agricultural products are stored in cages (500) by type, and the cages are transported by a transport unit (600). The cage (500) may have walls formed of a permeable material, such as wire mesh, to allow ozone to pass through the interior thereof. The transport unit (600) is also preferably configured in a form in which some areas are open, as illustrated in FIG. 4(b) and FIG. 6, rather than a completely closed belt conveyor, so that ozone supplied through the ozone injection port (110) can reach the cage (500) from both the top and bottom. That is, a pair of transport chains (620) arranged in parallel and circulating are moved by connecting both ends of a plurality of support bars (610) to a pair of transport chains (620), and the cage (500) is transported in a supported state supported on the support bars (610). Since the adjacent support bars (610) are spaced apart from each other by a predetermined distance, ozone (black arrow in FIG. 6) sprayed from the ozone spray port (110) installed at the bottom of the conveying unit (600) smoothly reaches the cage (500) and the agricultural products contained in the cage (500) through the space between the support bars (610).

[0034] If necessary, a camera may be added to capture images of agricultural products within the cage (500). Based on the image information obtained through the camera, the type of agricultural product within the cage (500) can be automatically identified. Specific techniques for identifying agricultural product types based on image images can utilize standardized tools such as YOLO. Furthermore, the ozone spray amount can be automatically adjusted based on the type of agricultural product.

[0035] As illustrated in FIG. 5, a partition (710) may be formed between the ozone circulation area (200) and the ozone blocking area (300) within the tunnel-shaped housing (700), and an opening (711) is formed in the partition (710) such that agricultural products or cages (500) to be sterilized can pass through. The partition (710) may contribute to lowering the ozone concentration within the ozone blocking area (300) by partially blocking the air flow between the ozone circulation area (200) and the ozone blocking area (300).

[0036] Fig. 11 illustrates the configuration of a partition (710) according to the second embodiment of the present invention. A partition door (712) capable of swinging is provided in the opening (711) of the partition (710). Normally, it is maintained in a vertical state by its own weight to close the opening (711) (Fig. 12(a)). However, when a cage (500) passes by, the cage (500) pushes the partition door (712) to swing it (Fig. 12(b)). Through the above configuration, the movement of ozone between the ozone circulation area (200) and the ozone blocking area (300) can be more reliably blocked.

[0037] Fig. 12 illustrates the configuration of a transport unit (600) according to a third embodiment of the present invention. A tension roller (631) and a tension roller raising / lowering unit (632) capable of adjusting the vertical height of the tension roller (631) may be provided on a portion of the transport chain (620). When the tension roller (631) rises and comes into contact with the lower end of the transport chain (620), the transport chain (620) inclines, and as a result, the cage (500) transported by the transport chain (620) also inclines. Preferably, two tension rollers (631) are provided, one each at the front and rear, so that the inclination direction of the transport chain (620) can be freely adjusted. That is, a pair of tension rollers (631) can change the inclination direction of the cage (500) of the transport chain (620) by moving up and down alternately, and the agricultural products inside the cage (500) move little by little, so that the entire surface of the agricultural products can be evenly exposed to sterilizing ingredients such as ozone.

[0038] The present invention relates to an agricultural product sterilization system that can be used industrially, and has industrial applicability.

Claims

1. Regarding an agricultural product sterilization system using low-temperature atmospheric pressure plasma, A transport unit (600) for transporting agricultural products to be sterilized; A tunnel-shaped housing (700) formed on the upper end of the above-mentioned conveying section (600), in which agricultural products to be sterilized enter at one end and agricultural products that have been sterilized exit at the other end; and A system for sterilizing agricultural products using low-temperature atmospheric pressure plasma, including an ozone injection port (110) for supplying ozone into the interior of the tunnel-shaped housing (700).

2. In claim 1, Inside the above tunnel-shaped housing (700), An ozone concentration injection area (120) where ozone is supplied by an ozone injection nozzle (110); An ozone circulation area (200) that circulates ozone inside a tunnel-shaped housing (700) by a circulation air nozzle (210); and Including an ozone blocking area (300) where outside air is introduced into the tunnel housing (700) by an outside air nozzle (310), A system for sterilizing agricultural products using low-temperature atmospheric pressure plasma, characterized in that an ozone blocking zone (300), an ozone circulation zone (200), an ozone concentration injection zone (100), an ozone circulation zone (200), and an ozone blocking zone (300) are formed in sequence inside a tunnel-shaped housing (700) based on the direction of movement of agricultural products.

3. In claim 2, an ozone generating unit (410) is further included, The ozone generated in the above ozone generating unit (410) is sprayed into the ozone concentration spray area (100) through the ozone spray port (110). A system for sterilizing agricultural products using low-temperature atmospheric pressure plasma, characterized in that the air within the above ozone concentration injection area (100) is supplied again to the ozone generating unit (410) by the first blower (421).

4. In claim 3, an agricultural product sterilization system using low-temperature atmospheric pressure plasma, characterized in that the ozone generator (410) includes a low-temperature atmospheric pressure plasma generator (411).

5. A system for sterilizing agricultural products using low-temperature atmospheric pressure plasma, characterized in that, in claim 2, the air within the ozone circulation area (200) is discharged through an exhaust pipe and then supplied back to the ozone circulation area (200) through a circulation air injection port (210) by a second blower (422).

6. In claim 2, a system for sterilizing agricultural products using low-temperature atmospheric pressure plasma, characterized in that external air is supplied to the ozone blocking area (300) through an external air injection (310) by a third blower (423), and air within the ozone blocking area (300) is discharged to an ozone depletion facility (430).

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