Pulsed electric field treatment device

Abstract

A pulsed electric field treatment device (1) is provided with: a first electrode (2) that has a first flow path (3) having a circular cross section through which a fluid to be treated flows formed therein; a first insulating member (4) that is connected to the first electrode and that has a second flow path (5) having a circular cross section through the first flow path formed therein; and a rod-shaped second electrode (6) that is disposed inside the first insulating member along the second flow path, and that is disposed closer to the first insulating member than the boundary between the first electrode and the first insulating member. A pulse voltage is applied between the first electrode and the second electrode.

Description

Pulse electric field treatment device

[0001] The present disclosure relates to a pulse electric field treatment device.

[0002] As an electroporation method for obtaining a bactericidal effect by damaging bacterial spores through an electrical action on liquids such as beverages, a treatment method using high-voltage pulses is known. In the above treatment, there are various types of electrode structures for generating an electric field, including a counter type and a coaxial type that generate an electric field in a direction perpendicular to the liquid flow path direction, and a butt type that generates an electric field in a direction parallel to the liquid flow path direction.

[0003] Japanese Patent Publication No. 2014-518083

[0004] The pulse electric field generation device shown in Patent Document 1 belongs to the butt type among the above types because electrodes to which different voltages are applied are arranged in contact along the flow path. As shown in this document, the electrodes are hollow cylindrical and have a tubular space inside, and the liquid to be pulse-electric-field-treated flows through this space. Based on this figure, it includes a cylindrical electrode that is the positive electrode and ground electrodes arranged on the upstream side and downstream side of this electrode, respectively, and all the electrodes are electrically separated by an insulating material. Based on such an electrode arrangement, an electric field along the direction of liquid flow is formed within this space.

[0005] According to this prior art, in the formed electric field distribution, the density of the electric force lines is high and the electric field is strong at the peripheral part where the cylindrical electrode and the ground electrode are close, while at the central part, the density of the electric force lines is low and the electric field strength is weak. Since the electric field strengths at the central part and the peripheral part are non-uniform, there is a problem that the bactericidal treatment ability of liquids such as beverages also varies between the central part and the peripheral part.

[0006] The present disclosure has been made to solve the above problems, and an object is to provide a pulse electric field treatment device that can improve the uniformity of the electric field strength between the central part and the peripheral part of the flow path through which the liquid to be sterilized flows, and reduce the variation in the bactericidal treatment ability.

[0007] The pulsed electric field processing apparatus of the present disclosure comprises a first electrode having a first flow channel formed inside through which a liquid to be processed flows and which has a circular cross-section; a first insulating member connected to the first electrode and having a second flow channel formed inside which a second flow channel has a circular cross-section and which passes through the first flow channel; and a rod-shaped second electrode arranged inside the first insulating member along the second flow channel and positioned on the side of the first insulating member that is closer to the first insulating member than the first boundary between the first electrode and the first insulating member, wherein a pulse voltage is applied between the first electrode and the second electrode.

[0008] The pulsed electric field processing apparatus of this disclosure comprises a first electrode with a flow path for the liquid to be processed formed inside, an insulating member connected to the first electrode and having a flow path for the liquid formed inside, and a second electrode located inside the insulating member and on the insulating member side of the first boundary between the first electrode and the insulating member. As a result, the electric field strength in the central part of the flow path can be increased, the uniformity of the electric field strength between the central and peripheral parts of the flow path can be improved, and variations in sterilization processing capacity can be reduced.

[0009] This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 1. This is a schematic diagram of the electric field formed in the pulse electric field processing device according to Embodiment 1. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 2. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 3. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 3. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 4. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 4. This is a diagram showing the electrode position adjustment member according to Embodiment 4. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 5. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 5. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 5. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 6. This is an overall configuration diagram of the pulse electric field processing device according to Embodiment 6.

[0010] Hereinafter, preferred embodiments of the pulsed electric field processing apparatus according to this disclosure will be described with reference to the drawings. The same parts and components will be denoted by the same reference numerals, and their detailed descriptions will be omitted. Furthermore, while the preferred embodiments of the pulsed electric field processing apparatus according to this disclosure will be described using liquid sterilization as an example, the pulsed electric field processing apparatus according to this disclosure is not limited to liquid sterilization. The pulsed electric field processing apparatus according to this disclosure can be used for a wide range of liquid processing applications, such as extraction of cytoplasm from cells, transfer of substances across cell membranes, atomization of solids in liquids, and activation of cells through cell stimulation.

[0011] Embodiment 1. Figure 1 shows the overall configuration of the pulse electric field processing device 1 according to this embodiment. In this figure, the first electrode 2 has a first flow path 3 formed inside through which the liquid to be sterilized flows, and the direction of the liquid flow is indicated by a shaded arrow. The first insulating member 4 connected to the first electrode 2 has a second flow path 5 formed inside that leads to the first flow path 3. In this embodiment and subsequent embodiments, the cross-sectional shape of the liquid flow path is always circular.

[0012] A rod-shaped second electrode 6 is positioned inside the first insulating member 4 along the second flow path 5, and this second electrode 6 is positioned on the side of the first insulating member 4 rather than the boundary (first boundary) between the first electrode 2 and the first insulating member 4. As shown by A-A in Figure 1, this second electrode 6 is supported in the second flow path 5 by a support member 7 that supports it from the inner surface of the first insulating member 4. When a pulse voltage is applied between the first electrode 2 and the second electrode 6 by a pulse power supply, an electric field is formed between the first electrode 2 and the second electrode 6 in the first flow path 3 and the second flow path 5, and the liquid flowing through this part is sterilized by this electric field.

[0013] For example, Figure 2 shows a schematic diagram of the electric field formed when a high-voltage pulse voltage is applied to the first electrode 2 and the second electrode 6 is grounded. In the electrode structure shown in the prior art documents, both the high-voltage side electrode and the grounded side electrode have a cylindrical structure, so the density of electric field lines formed between them is low in the central part, and therefore the electric field strength is non-uniform, being strong in the peripheral part of the flow path and weak in the central part. In contrast, with the pulse electric field processing device 1 according to this embodiment, electric field lines are formed toward the second electrode 6 placed in the second flow path 5, and the electric field lines concentrate near the second electrode 6, so the electric field strength in this part can be increased. This improves the non-uniformity of the electric field distribution.

[0014] Furthermore, since the second electrode 6 is positioned on the side of the first insulating member 4 rather than the boundary between the first electrode 2 and the first insulating member 4, the second electrode 6 can be moved further away from the first electrode 2 compared to the case where the second electrode 6 protrudes beyond the boundary between the first electrode 2 and the first insulating member 4 into the interior of the first electrode 2. As a result, the electrical resistance between the second electrode 6 and the first electrode 2 can be made relatively high, and the current value flowing between these two electrodes can be made low, which has the advantage of being economical as the capacity of the pulse power supply can be reduced.

[0015] Embodiment 2. Figure 3 shows the overall configuration of the pulse electric field processing device 1a according to this embodiment. Compared to the pulse electric field processing device 1 according to the embodiment, this pulse electric field processing device 1a has an additional mixer unit 8. As shown by B-B in this figure, this mixer unit 8 is equipped with a plurality of blades 9 and has the function of stirring the liquid by rotating them. In Figure 3, this mixer unit 8 is arranged between the first electrode 2 and the first insulating member 4, but it does not necessarily have to be adjacent to the first electrode 2. It is sufficient for it to be arranged either upstream or downstream of the first electrode 2 in the direction of liquid flow and be able to perform the function of stirring the liquid, and it may be arranged upstream of the first insulating member 4 or downstream of the first electrode 2.

[0016] The pulse electric field processing device 1a according to this embodiment is equipped with a mixer unit 8 on the upstream or downstream side of the liquid flow direction relative to the first electrode 2. This mixer unit 8 stirs the liquid during the sterilization process, and even if non-uniformity in the sterilization process is observed due to the electric field distribution, the uniformity of the sterilization process can be improved.

[0017] Embodiment 3. Figure 4 shows the overall configuration of the pulse electric field processing device 1b according to this embodiment. In this pulse electric field processing device 1b, the third electrode 2a is connected to the end face of the first insulating member 4 on the opposite side of the boundary where the first electrode 2 and the first insulating member 4 are connected, and a third flow path 3a leading to the second flow path 5 is formed inside. The first electrode 2 and the third electrode 2a are kept at the same potential by external wiring, and the pulse power supply applies a pulse voltage between the first electrode 2 and the third electrode 2a and the second electrode 6, thereby forming an electric field inside the pulse electric field processing device 1b.

[0018] As yet another configuration, Figure 5 shows the overall configuration of the pulsed electric field processing device 1c. In this pulsed electric field processing device 1c, the second insulating member 4a is connected to the end face of the first electrode 2 on the opposite side of the boundary (first boundary) where the first electrode 2 and the first insulating member 4 are connected, and a fourth flow path 5a leading to the first flow path 3 is formed inside it. The rod-shaped fourth electrode 6a is arranged inside the second insulating member 4a along the fourth flow path 5a and is positioned on the side of the second insulating member 4a than the boundary (second boundary) between the first electrode 2 and the second insulating member 4a. Furthermore, the second electrode 6 and the fourth electrode 6a are kept at the same potential by external wiring, and the pulse power supply applies a pulse voltage between the first electrode 2, the second electrode 6, and the fourth electrode 6a, thereby forming an electric field inside the pulsed electric field processing device 1c.

[0019] As described above, the pulse electric field processing devices 1b and 1c according to this embodiment allow for a greater number of electrode placement locations compared to the pulse electric field processing device 1 shown in Embodiment 1, thereby increasing the number of times the liquid flows through the electric field. This enhances the sterilization effect of the liquid being processed.

[0020] Furthermore, while Figure 4 shows a configuration in which the first electrode 2 and the third electrode 2a are connected, and Figure 5 shows a configuration in which the second electrode 6 and the fourth electrode 6a are connected to reduce the number of power supplies, these connections are not necessarily required. In Figure 4, it is also possible to apply different pulse voltages between the first electrode 2 and the second electrode 6, and between the third electrode 2a and the second electrode 6, using separate pulse power supplies. Similarly, in Figure 5, it is also possible to apply different pulse voltages between the second electrode 6 and the first electrode 2, and between the fourth electrode 6a and the first electrode 2, using separate pulse power supplies. By doing so, the sterilization processing capacity can be made variable by combining pulse power supply voltages to generate an electric field according to the required sterilization capacity.

[0021] Embodiment 4. Figure 6 shows the overall configuration of the pulse electric field processing device 1d according to this embodiment. In this pulse electric field processing device 1d, the second electrode 6b is characterized by having a shape that tapers as it approaches the boundary between the first electrode 2 and the first insulating member 4 along the second flow path 5, and the other configurations are the same as those of the pulse electric field processing device 1 according to Embodiment 1. Figure 7 shows the overall configuration of the pulse electric field processing device 1e according to this embodiment. In this pulse electric field processing device 1e, the fourth electrode 6c is characterized by having a shape that tapers as it approaches the boundary between the first electrode 2 and the second insulating member 4a along the fourth flow path 5a, and the other configurations are the same as those of the pulse electric field processing device 1c according to Embodiment 3.

[0022] According to the pulse electric field processing device 1d of this embodiment, the second electrode 6b has a shape that tapers as it approaches the boundary between the first electrode 2 and the first insulating member 4 along the second flow path 5, thus having the effect of further increasing the electric field strength around the tip of the second electrode 6b. Furthermore, since the area in which the first electrode 2 and the second electrode 6b face each other can be reduced, the resistance value of both electrodes can be increased and the current value flowing between the two electrodes can be reduced. Therefore, the capacity of the pulse power supply can be reduced, which has the advantage of being economical.

[0023] Similarly, according to the pulse electric field processing device 1e of this embodiment, the fourth electrode 6c has a shape that tapers as it approaches the boundary between the first electrode 2 and the second insulating member 4a along the fourth flow path 5a, thus having the effect of further increasing the electric field strength around the tip of the fourth electrode 6c. Furthermore, since the area in which the first electrode 2 and the fourth electrode 6c face each other can be reduced, the resistance value of both electrodes can be increased and the current value flowing between the two electrodes can be reduced. Therefore, the capacity of the pulse power supply can be reduced, which has the advantage of being economical.

[0024] Furthermore, as shown in Figure 8, the second electrodes 6 and 6b may be equipped with a first electrode position adjustment member 10 that allows adjustment of the position of the electrodes along the second flow path 5. This first electrode position adjustment member 10 adjusts the position of the second electrodes 6 and 6b along the second flow path 5 by inserting a required number of washers or the like. Similarly, the fourth electrode 6c may be equipped with a second electrode position adjustment member 10a that allows adjustment of the position of the electrode along the fourth flow path 5a. By making the positions of the second electrodes 6 and 6b and the fourth electrode 6c along the flow path adjustable in this way, the distance between the first electrode 2 and the second electrodes 6 and 6b, and the distance between the first electrode 2 and the fourth electrode 6c can be changed, thereby changing the electric field formed between these two electrodes and enabling the formation of an electric field according to the required sterilization capacity. In addition, since the resistance between the two electrodes can be changed, the amount of current flowing between the two electrodes can also be adjusted, and the power supply capacity can be reduced.

[0025] Embodiment 5. Figure 9 shows the overall configuration of the pulse electric field processing device 1f according to this embodiment, characterized in that the first electrode 2b has a shape in which the opening of the first flow path 3b becomes smaller as it approaches the boundary between the first insulating member 4 and the first electrode 2b along the first flow path 3b. Figure 10 shows the overall configuration of the pulse electric field processing device 1g according to this embodiment, characterized in that the third electrode 2c has a shape in which the opening of the third flow path 3c becomes smaller as it approaches the boundary between the first insulating member 4 and the third electrode 2c along the third flow path 3c.

[0026] According to the pulse electric field processing device 1f and pulse electric field processing device 1g of this embodiment, which have the features described above, when viewing the first electrode 2b and the third electrode 2c from the second electrode 6 located in the second flow path 5, only the protruding portions of the first electrode 2b and the third electrode 2c located near the boundary between the first insulating member 4 and the first electrode 2b and the third electrode 2c are visible, and the wall surface away from the boundary is hidden in the shadow of these protruding portions and becomes difficult to see. This means that the area in which the second electrode 6 and the first electrode 2b and the third electrode 2c face each other is effectively reduced, so the current value flowing between the two electrodes can be suppressed, and the power supply capacity can be reduced.

[0027] Furthermore, in the pulsed electric field processing device 1h shown in Figure 11, the first electrode 2d has a first channel 3d formed inside it, which has an opening (diameter) smaller than the opening (diameter) of the second channel 5, and in the pulsed electric field processing device 1i shown in Figure 12, the third electrode 2e has a third channel 3e formed inside it, which has an opening smaller than the opening of the second channel 5. In such pulsed electric field processing devices 1h and 1i, the area in which the second electrode 6 faces the first electrode 2d and the third electrode 2e is effectively reduced, so the current value flowing between the two electrodes can be suppressed, and the power supply capacity can be reduced.

[0028] Furthermore, in the pulse electric field processing devices 1h and 1i shown in Figures 11 and 12, the first electrode 2d and the third electrode 2e are characterized in that their end faces in contact with the boundary with the first insulating member 4 are chamfered with an R-chamfer. Such pulse electric field processing devices 1h and 1i can suppress the current flowing between the first electrode 2d and the third electrode 2e and the second electrode 6 as described above, and also prevent fluid stagnation, allowing the fluid to flow smoothly, thus preventing the occurrence of liquid accumulation from a hygienic standpoint.

[0029] Embodiment 6. Figure 13 shows the overall configuration of the pulse electric field processing device 1j according to this embodiment, characterized in that the first insulating member 4 has a first power supply section 9a provided on the end face of the first insulating member 4 on the opposite side of the boundary where the first electrode 2 and the first insulating member 4 are connected, and the second electrode 6 is connected to the first power supply section 9a. If such a first power supply section 9a is not provided, it is necessary to separately provide a current introduction terminal that penetrates the first insulating member to supply power to the second electrode 6, but by providing such a first power supply section 9a, power can be supplied to the second electrode 6 arranged in the second flow path 5 relatively easily.

[0030] Figure 14 shows the overall configuration of the pulse electric field processing device 1k according to this embodiment, wherein the first insulating member 4 has a second power supply section 9b connected to the end face of the first insulating member 4 on the opposite side of the boundary where the first electrode 2 and the first insulating member 4 are connected, and the second insulating member 4a has a third power supply section 9c connected to the end face of the second insulating member 4a on the opposite side of the boundary where the first electrode 2 and the second insulating member 4a are connected, the second electrode 6 is connected to the second power supply section 9b, and the fourth electrode 6a is connected to the third power supply section 9c. If the second power supply section 9b and the third power supply section 9c are not provided, it is necessary to separately provide current introduction terminals that penetrate the first insulating member 4 and the second insulating member 4a to supply power to the second electrode 6 and the fourth electrode 6a. However, by providing the second power supply section 9b and the third power supply section 9c, power can be supplied relatively easily to the second electrode 6 located in the second flow path 5 and the fourth electrode 6a located in the fourth flow path 5a.

[0031] While this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are envisioned within the scope of the art disclosed in this specification. For example, these include modifying, adding or omitting at least one component, or extracting at least one component and combining it with a component from another embodiment.

[0032] 1, 1h, 1f, 1d, 1j, 1b, 1c, 1k, 1a: Pulse electric field processing device, 3, 3d, 3b: First flow path, 2, 2d, 2b: First electrode, 5: Second flow path, 4: First insulating member, 6, 6b: Second electrode, 9a: First power supply unit, 3a: Third flow path, 2a: Third electrode, 5a: Fourth flow path, 4a: Second insulating member, 6a: Fourth electrode, 9b: Second power supply unit, 9c: Third power supply unit, 8: Mixer unit

Claims

1. A pulsed electric field processing apparatus comprising: a first electrode having a first flow channel formed inside through which the liquid to be processed flows and which has a circular cross-section; a first insulating member connected to the first electrode and having a second flow channel formed inside which is connected to the first flow channel and which has a circular cross-section; and a rod-shaped second electrode arranged inside the first insulating member along the second flow channel and positioned on the side of the first insulating member beyond the first boundary between the first electrode and the first insulating member, wherein a pulse voltage is applied between the first electrode and the second electrode.

2. The pulsed electric field processing apparatus according to claim 1, characterized in that the first electrode has a portion in which the diameter of the first flow path is smaller than the diameter of the second flow path.

3. The pulse field treatment apparatus according to claim 1 or 2, characterized in that the first electrode has a shape in which the end face in contact with the first boundary is chamfered with an R chamfer.

4. The pulse field treatment apparatus according to any one of claims 1 to 3, characterized in that the first electrode has a shape such that the diameter of the first flow path decreases as it approaches the first boundary along the first flow path.

5. The pulse electric field processing apparatus according to any one of claims 1 to 4, characterized in that the second electrode has a shape that tapers as it approaches the first boundary along the second flow path.

6. The pulse electric field processing apparatus according to any one of claims 1 to 5, characterized in that the first insulating member has a first power supply portion provided on the end face of the first insulating member opposite to the first boundary, and the second electrode is connected to the first power supply portion.

7. The pulse field treatment apparatus according to any one of claims 1 to 5, further comprising a third electrode connected to the end face of the first insulating member on the opposite side of the first boundary, having a third flow channel formed inside which is connected to the second flow channel and has a circular cross-section, wherein the pulse voltage is applied between the first electrode and the second electrode and between the third electrode and the second electrode.

8. A pulse field treatment apparatus according to any one of claims 1 to 6, comprising: a second insulating member connected to the end face of the first electrode on the opposite side of the first boundary, having a fourth flow path formed inside it that is connected to the first flow path and has a circular cross-section; and a rod-shaped fourth electrode disposed inside the second insulating member along the fourth flow path and positioned on the side of the second insulating member that is closer to the second insulating member than the second boundary between the first electrode and the second insulating member, wherein the pulse voltage is applied between the first electrode and the second electrode and between the first electrode and the fourth electrode.

9. The pulse electric field processing apparatus according to claim 8, characterized in that the first insulating member has a second power supply portion connected to the end face of the first insulating member on the side opposite to the first boundary, the second insulating member has a third power supply portion connected to the end face of the second insulating member on the side opposite to the second boundary, the second electrode is connected to the second power supply portion, and the fourth electrode is connected to the third power supply portion.

10. The pulse electric field processing apparatus according to any one of claims 1 to 9, characterized in that a mixer unit for agitating the liquid is provided on either the upstream or downstream side of the liquid flow direction relative to the first electrode.

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