Defoaming apparatus and defoaming method

Abstract

To provide a technique that achieves superior foam destruction power with a simple configuration.SOLUTION: A defoaming apparatus comprises: a high-voltage pulse generation unit for generating a high-voltage pulse; and an electrode unit comprising a high-voltage electrode which receives the high-voltage pulse from the high-voltage pulse generation unit and a counter electrode and which performs defoaming by generating a high-voltage pulse discharge between the high-voltage electrode and the counter electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a defoaming device and a defoaming method. [Background technology]

[0002] Conventionally, there are known techniques for breaking up bubbles that form on the surface of a liquid or solid. For example, Patent Document 1 discloses a technique for calming bubbles by irradiating molten slag with microwaves. Patent Documents 2 to 8 also disclose techniques for breaking up bubbles on the liquid surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-255426 [Patent Document 2] Japanese Patent Application Publication No. 5-317606 [Patent Document 3] Japanese Patent Application Publication No. 6-191595 [Patent Document 4] Japanese Patent Application Publication No. 63-104620 [Patent Document 5] Japanese Patent Application Laid-Open No. 2007-61717 [Patent Document 6] International Publication No. 2007 / 086339 [Patent Document 7] International Publication No. 2007 / 132590 [Patent Document 8] Japanese Patent Application Laid-Open No. 2012-183521 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Documents 1 to 8, foam is destroyed by microwaves, laser light, sound waves, ultrasound, etc. When microwaves or laser light are used to defoam, the device configuration becomes complicated. Furthermore, when sound waves or ultrasound are used to defoam, the power of foam destruction is insufficient compared to when microwaves are used. The present disclosure aims to provide a technology that has a simple configuration and superior power of foam destruction. [Means for solving the problem]

[0005] In order to solve the above problems, the present disclosure uses high-voltage pulse discharge to destroy bubbles, thereby improving the power of foam destruction with a simple configuration.

[0006] Specifically, the present disclosure provides a defoaming device comprising: a high-voltage pulse generating unit that generates high-voltage pulses; an electrode unit having a high-voltage electrode to which the high-voltage pulses are applied from the high-voltage pulse generating unit; and a counter electrode, the electrode unit defoaming by generating a high-voltage pulse discharge between the high-voltage electrode and the counter electrode. The defoaming device according to the present disclosure can perform defoaming using the electrode that generates the high-voltage pulse discharge. The defoaming mechanism is believed to be due to shock waves generated by the high-voltage pulse discharge, decomposition of hydrophobic components by radicals, reduction of surface tension, and electrostatic forces by ions. The voltage of the high-voltage pulse is preferably 3 kV to 100 kV, but there is no particular upper limit for the high-voltage pulse discharge, and defoaming may be performed using any high-voltage pulse discharge that is practically feasible.

[0007] In the above-described foam deactivator, foam may be generated on the surface of the liquid in the container, and the high-voltage pulse generating unit may increase the frequency of the high-voltage pulse as the rising speed of the foam increases, thereby creating an equilibrium state in which the upper surface of the foam does not rise. The foam deactivator can destroy foam generated on the liquid surface. Note that the foam deactivator may destroy all foam on the liquid surface, or, in a state in which foam is generated one after another, may destroy the uppermost foam so as to create an equilibrium state in which the upper surface of the foam does not rise.

[0008] In the above-mentioned defoaming device, the high-voltage electrode and the liquid surface may not be in contact with each other. For example, a gap can be provided between the high-voltage electrode and the liquid surface. Note that, since the higher the voltage of the high-voltage pulse, the higher the discharge energy, the larger this gap can be set. Furthermore, the counter electrode does not necessarily have to be placed in the liquid; defoaming can be performed by generating a high-voltage pulse discharge between a high-voltage electrode placed on the liquid surface and the counter electrode. Of course, in the above-mentioned defoaming device, defoaming can also be performed by generating a high-voltage pulse discharge while the high-voltage electrode is in contact with the surface of the foam while being separated from the liquid surface. Note that the liquid surface refers to the surface of the liquid, and foam is generated on the liquid surface.

[0009] In the above-described defoaming device, the distance between the high-voltage electrode and the liquid surface may be 1 mm to 10 mm, and the high-voltage pulse generating unit may generate the high-voltage pulse of 3 kV or more. For example, when the distance between the high-voltage electrode and the liquid surface is 1 mm to 60 mm, defoaming can be performed by high-voltage pulse discharge using a high-voltage pulse of 3 kV or more. When the distance between the high-voltage electrode and the liquid surface is 60 mm, defoaming can be performed by high-voltage pulse discharge using a high-voltage pulse of 100 kV or more.

[0010] Here, the present disclosure can be viewed from the perspective of a defoaming method. That is, the present disclosure may be a defoaming method including: generating a high-voltage pulse by a high-voltage pulse generating unit; and defoaming by generating a high-voltage pulse discharge between the high-voltage electrode to which the high-voltage pulse is applied from the high-voltage pulse generating unit and a counter electrode. [Effects of the Invention]

[0011] According to the present disclosure, the power of foam destruction can be improved with a simple configuration. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing a defoaming device according to an embodiment. [Figure 2] FIG. 2 is a circuit diagram of a high-voltage pulse generating unit in the embodiment. [Figure 3] FIG. 3 is a flowchart illustrating a defoaming method according to an embodiment. [Figure 4] FIG. 4 is a graph showing the relationship between the gas flow rate and the frequency of the high voltage pulse at the equilibrium state of the foam. [Figure 5] FIG. 5 is a graph showing the relationship between the gas flow rate and the frequency of the high voltage pulse at the equilibrium state of the foam. [Figure 6] FIG. 6 is a graph showing the relationship between the gap between the high-voltage electrode and the liquid surface and the defoaming rate. [Figure 7] FIG. 7 is a graph showing the relationship between the voltage of the high-voltage pulse and the number of times high-voltage pulse discharge is applied. [Figure 8] FIG. 8 is a diagram illustrating an application example of the defoaming device and the defoaming method according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Below, a defoaming device and a defoaming method according to embodiments of the present disclosure will be described with reference to the drawings. Note that the configurations of the following embodiments are examples, and the present invention is not limited to the configurations of these embodiments. Note that in this disclosure, the notation "X to Y" representing a numerical range means a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified.

[0014] <Embodiment> 1 is a schematic diagram showing a defoaming device according to an embodiment. The defoaming device 10 is a device that generates a high voltage pulse. The defoamer 10 includes a high-voltage pulse generator 11 that generates an electric discharge and an electrode unit 12 that generates a high-voltage pulse discharge. The defoamer 10 generates a high-voltage pulse discharge to destroy bubbles that form on the surface of a liquid or a solid, thereby defoaming the liquid. As shown in FIG. 1 , a glass tube 41 is inserted into the liquid, one end of which is connected to an air pump 40, and the other end is immersed in the liquid. In this embodiment, an experiment was conducted in which air was pumped into the liquid using the air pump 40 to destroy bubbles (gas bubbles) B that formed on the liquid surface using the defoamer 10. In this experiment, a tall beaker 30 containing 49 mL of dibutyl phosphate (DBP) and 1 mL of alumina sol (Clearsol N, manufactured by Kawaken Fine Chemicals Co., Ltd.) was prepared. Air was pumped into the liquid in the tall beaker 30 via the glass tube 41 from the air pump 40, generating bubbles B in the liquid and on the liquid surface S. In this embodiment, a tall beaker 30 having a diameter of 35 mm and a height of 130 mm and a glass tube 41 having a diameter of 2 mm were used. Also, an air pump 40 capable of supplying air at a gas flow rate of 0.15 L / min to 0.5 L / min was used.

[0015] The electrode unit 12 of the defoaming device 10 includes a high-voltage electrode 12A to which a high-voltage pulse is applied from the high-voltage pulse generating unit 11, and a counter electrode 12B connected to a ground potential. The high-voltage electrode 12A is electrically connected to the high-voltage pulse generating unit 11 via an electric wire 13, and high-voltage pulses are supplied from the high-voltage pulse generating unit 11 to the electrode unit 12A. The high-voltage electrode 12A used in this embodiment has a needle electrode structure extending into a glass tube, and its tip is disposed with a gap from the liquid surface S. Hereinafter, the gap between the tip of the high-voltage electrode 12A and the liquid surface S is referred to as gap A. For example, gap A can be set appropriately between 1 mm and 20 mm. The counter electrode 12B is disposed in the liquid and connected to a ground potential. Therefore, the potential in the liquid is 0 V. The electrode unit 12 of the defoaming device 10 generates a high-voltage pulse discharge between the high-voltage electrode 12A and the counter electrode 12B, thereby destroying the foam. The electrode portion 12 defoams by destroying the foam.

[0016] Next, the high-voltage pulse generating unit 11 will be described in detail. FIG. 2 is an example of a circuit diagram of the high-voltage pulse generating unit 11 in this embodiment. The high-voltage pulse generating unit 11 includes a pulse generating circuit 11A that generates high-voltage pulses, a pulse compression circuit 11B that compresses the generated pulses, and an output electrode 11C. The pulse generating circuit 11A includes a high-voltage power supply 20, a capacitor C0, a magnetic assist SI0, the primary side of a step-up transformer Tr, and a thyristor 21. The capacitance of the capacitor C0 is 2.24 μF. The magnetic assist SI0 is a saturable inductor. The thyristor 21 is a switching element that can switch the forward current from an off state to an on state by inputting a control signal to the gate terminal.

[0017] The pulse compression circuit 11B has a secondary side of a step-up transformer Tr, capacitors C1 to C3, and magnetic assists SI1 to SI4. The winding ratio between the primary and secondary sides of the step-up transformer Tr is 1:30. The capacitances of the capacitors C1 and C2 are 2 nF, and the capacitance of the capacitor C3 is 0.7 nF. The pulse compression circuit 11B has a three-stage compression circuit composed of capacitors C1 to C3 and magnetic assists SI1, SI2, and SI4, with the magnetic assist SI3 being connected in parallel with the third-stage capacitor C3. The magnetic assist SI3 is provided to further compress the pulse width. The magnetic assists SI1 to SI4 are saturable inductors.

[0018] In the high-voltage pulse generating unit 11, a predetermined high voltage (for example, 800 V) is applied to the capacitor C0 from the high-voltage power supply 20, and the capacitor C0 is charged. When the capacitor C0 is being charged, the thyristor 21 is in an OFF state, blocking forward current. When charging of the capacitor C0 is completed, a control signal is input to the gate electrode of the thyristor 21 from a controller (not shown), and the thyristor 21 is turned ON, passing forward current, and the charging voltage Vc of the capacitor C0 is applied to the magnetic assist SI0. The charging voltage of the capacitor C0 When the time integral value of the pressure Vc reaches a predetermined value determined by the characteristics of the magnetic assist SI1, the magnetic assist SI0 is saturated and the inductance of the magnetic assist SI1 decreases. A current i flows through the primary side of the step-up transformer Tr into a circuit consisting of the capacitor C0, magnetic assist SI0, the primary side of the step-up transformer Tr, and the thyristor 21. C flows. A magnetic flux generated in the step-up transformer Tr induces a current on the secondary side of the step-up transformer Tr, causing the current to flow through a circuit formed by the secondary side of the step-up transformer Tr and capacitor C1, thereby charging capacitor C1. When a current is induced from the primary side to the secondary side of the step-up transformer Tr, the voltage is boosted in accordance with the turns ratio of the primary winding to the secondary winding. In this embodiment, the turns ratio of the primary side to the secondary side is 1:30, and capacitor C1 is charged with a voltage 30 times that of capacitor C0.

[0019] The time integral value of the high voltage charged in the capacitor C1 is determined by the characteristics of the magnetic assist SI1. When the inductance of the magnetic assist SI1 reaches a predetermined value, the magnetic assist SI1 is saturated and the inductance of the magnetic assist SI1 decreases. The charge stored in capacitor C2 is transferred to capacitor C2. Charge is stored in capacitor C2, and a voltage is applied to magnetic assist SI2. When the time integral value of the charging voltage of capacitor C2 reaches a predetermined value determined by the characteristics of magnetic assist SI2, magnetic assist SI2 is saturated and the inductance of magnetic assist SI2 decreases. As a result, the charge stored in capacitor C2 is transferred to capacitor C3. Charge is stored in capacitor C3, and a voltage is applied to magnetic assist SI4. When the time integral value of the charging voltage of capacitor C3 reaches a predetermined value determined by the characteristics of magnetic assist SI4, magnetic assist SI4 is saturated and the inductance of magnetic assist SI4 decreases, and current i O And the voltage V O The high voltage is output from the output electrode 11C.

[0020] The high-voltage pulse generating unit 11 supplies high-voltage pulses to the high-voltage electrode 12A shown in FIG. 1 at a predetermined oscillation frequency (for example, 1 Hz to 500 Hz) by repeating the above-described high-voltage pulse output operation by the switching operation of the thyristor 21. In this way, in the high-voltage pulse generating unit 11, after the capacitor C0 is charged by the DC power supply, when the thyristor 21 is turned on, the charge is transferred to the capacitor C1 via the step-up transformer Tr, and the magnetic pulse is compressed by resonance between the magnetic assist SI1, the capacitor C2, the magnetic assist SI2, the capacitor C3, and the magnetic assist SI4, and the output voltage V O Output.

[0021] Next, the steps of the defoaming method according to this embodiment will be described. Fig. 3 is a flowchart of the defoaming method according to this embodiment. In the defoaming method according to this embodiment, first, a high-voltage pulse is generated by the high-voltage pulse generating unit 11 (see Figs. 1 and 2) (step S101). Next, foams are destroyed by generating a high-voltage pulse discharge between the high-voltage electrode 12A and the counter electrode 12B shown in Fig. 1. In the defoaming method according to this embodiment, foams are destroyed by destroying them.

[0022] In the defoaming device and defoaming method according to this embodiment, a gap A can be provided between the high-voltage electrode 12A and the liquid surface S, as shown in Fig. 1. In other words, in the defoaming device and defoaming method according to this embodiment, foam B can be eliminated without the high-voltage electrode 12A being in contact with the liquid surface S. The gap A can also be made 20 mm or more by increasing the voltage of the high-voltage pulse. Furthermore, the counter electrode 12B does not necessarily have to be placed in the liquid; defoaming can be performed by generating a high-voltage pulse discharge between the high-voltage electrode 12A and the counter electrode 12B, which are placed above the liquid surface S.

[0023] The principle of the defoaming device and defoaming method according to this embodiment is that the foam is destroyed by shock waves generated by high-voltage pulse discharge, decomposition of hydrophobic components by radicals, reduction of surface tension, and electrostatic force by ions. The high-voltage pulse discharge can be carried out in a form in which it advances directly from the high-voltage electrode 12A to the liquid surface, or in which the high-voltage electrode 12A and the counter electrode 12B are positioned a little distance away from the foam. Foam can also be defoamed by placing a high-voltage electrode 12A and a counter electrode 12B at a position slightly away from the foam, generating a high-voltage pulse discharge between the electrodes. The voltage of the high-voltage pulse is preferably 3 kV to 100 kV. The lower the voltage, the lower the discharge energy, so the shorter the gap A must be. Furthermore, the higher the voltage, the higher the discharge energy, so the longer the gap A can be, and defoaming can be performed by placing the high-voltage electrode 12A and the counter electrode 12B at a position slightly away from the foam. There is no particular upper limit for the high-voltage pulse discharge, and defoaming may be performed at any voltage that is practically feasible.

[0024] The defoaming device and defoaming method according to this embodiment can also defoam by generating a high-voltage pulse discharge between the high-voltage electrode 12A and the counter electrode 12B while the high-voltage electrode 12A is in contact with the liquid surface S. The defoaming device and defoaming method according to this embodiment can also defoam by generating a high-voltage pulse discharge while the high-voltage electrode 12A is in contact with the surface of the foam B while separating the high-voltage electrode 12A from the liquid surface S. The counter electrode 12B is preferably connected to ground potential, but the potential difference between the high-voltage electrode 12A and the counter electrode 12B may be equal to or greater than the dielectric breakdown strength. If the potential difference is equal to or greater than the dielectric breakdown strength, a high-voltage pulse discharge can be generated between the high-voltage electrode 12A and the counter electrode 12B.

[0025] Next, we will explain the results of an experiment in which foam breaking was actually performed using the experimental method described in Figure 1. First, the gas flow rate injected into the liquid by the air pump 40 was changed from 0.2 L / min to 0.6 L / min in 0.1 L / min increments, and the frequency of the high-voltage pulse that would create an equilibrium state in which the upper surface of foam B did not rise was examined. The voltage was kept constant at either 20 kV, 23 kV, or 26 kV. The gap A was set to 3 mm.

[0026] Figure 4 is a graph showing the relationship between gas flow rate and high-voltage pulse frequency in an equilibrium state where the upper surface of foam B does not rise. In the graph of Figure 4, the horizontal axis represents gas flow rate (L / min), and the vertical axis represents high-voltage pulse frequency (Hz). In the graph of Figure 4, line L1 connecting the points plotted with "●" shows the relationship between gas flow rate and frequency when the voltage is 20 kV, line L2 connecting the points plotted with "▲" shows the relationship between gas flow rate and frequency when the voltage is 23 kV, and line L3 connecting the points plotted with "■" shows the relationship between gas flow rate and frequency when the voltage is 26 kV. Lines L1 and L2 completely overlapped.

[0027] As can be seen from the graph in Figure 4, when the gas flow rate is increased, a higher frequency high-voltage pulse discharge is required to maintain the equilibrium state of foam B. More specifically, when the voltage is 20 kV or 23 kV, the equilibrium state of foam could be maintained within a frequency range of 10 Hz to 80 Hz. Furthermore, when the voltage is 26 kV, the equilibrium state of foam could be maintained within a frequency range of 4 Hz to 40 Hz. Thus, when the voltage is 26 kV, the equilibrium state of foam could be maintained at a relatively lower frequency compared to when the voltage is 20 kV or 23 kV.

[0028] Next, the experiment described in Figure 4 was repeated at a lower voltage. We investigated the frequency of the high-voltage pulse that would create an equilibrium state where the upper surface of bubble B did not rise at each gas flow rate. The voltage was kept constant at either 8 kV or 15 kV. Gap A was set to 1 mm.

[0029] Figure 5(A) is a graph showing the relationship between the gas flow rate and the frequency of the high-voltage pulse in an equilibrium state where the upper surface of foam B does not rise when the gas flow rate is set to 0.05 L / min, 0.1 L / min, 0.15 L / min, and 0.2 L / min, respectively, and the voltage is 8 kV. Figure 5(B) is a graph showing the relationship between the gas flow rate and the frequency of the high-voltage pulse in an equilibrium state where the upper surface of foam B does not rise when the gas flow rate is set to 0.1 L / min, 0.15 L / min, 0.2 L / min, and 0.3 L / min, respectively, and the voltage is 15 kV. In the graphs of Figures 5(A) and 5(B), the horizontal axis represents the gas flow rate (L / min), and the vertical axis represents the frequency (Hz) of the high voltage pulse.

[0030] As can be seen from the graph in Figure 5(A), an equilibrium state of foam B can be formed even at a voltage of 8 kV. Furthermore, when the gas flow rate is increased, a higher frequency high-voltage pulse discharge is required to maintain the equilibrium state of foam B. In this experiment, when the voltage was 8 kV, the equilibrium state of foam could be maintained within a frequency range of 10 Hz to 80 Hz. Similarly, as can be seen from the graph in Figure 5(B), an equilibrium state of foam B can be formed even at a voltage of 15 kV. Furthermore, when the gas flow rate is increased, a higher frequency high-voltage pulse discharge is required to maintain the equilibrium state of foam B. In this experiment, when the voltage was 15 kV, the equilibrium state of foam could be maintained within a frequency range of 40 Hz to 80 Hz.

[0031] Even when the voltage was relatively small, such as 8 kV to 15 kV, the frequency required to maintain the equilibrium state of foam B was within the range of 10 Hz to 80 Hz, and this frequency range was similar to the range when the voltage was 20 kV to 26 kV shown in Figure 4. The results shown in Figures 5(A) and 5(B) and the results shown in Figure 4 differ in gas flow rate, but it was found that the larger the gas flow rate, the more the equilibrium state of foam B could be maintained by high-frequency high-voltage pulses.

[0032] Here, the gas flow rate can be converted into the rate at which the foam rises in the tall beaker 30. The foam defoaming device and foam defoaming method according to this embodiment can suppress the rise of foam in an environment where bubbles are generated one after another in a liquid due to a chemical reaction or the like. For example, in the foam defoaming device and foam defoaming method according to this embodiment, the faster the rate at which the foam rises, the higher the frequency of the high-voltage pulse can be made to create an equilibrium state in which the upper surface of the foam does not rise.

[0033] In the next experiment, a state in which foam B was present on the liquid surface in the tall beaker 30 was created in advance, and the extent to which static foam B could be defoamed by applying 10 high-voltage pulses was examined. Figure 6 is a graph showing gap A and the percentage of foam defoamed. In the graph of Figure 6, the horizontal axis represents the length (mm) of gap A, and the left vertical axis represents the percentage of foam defoamed (%) of foam B. The percentage of foam defoamed was the result of visual observation. Gap A was set to 3 mm, 5 mm, 7 mm, 10 mm, and 20 mm. The height of foam B from the liquid surface was set to 20 mm. The voltage was set to 27 kV.

[0034] In the graph of FIG. 6, line L4 connecting the points plotted with "●" indicates the defoaming rate at each gap A. When gap A was 3 mm, the defoaming rate reached 100% after applying 10 high-voltage pulses. When gap A was 5 mm, the defoaming rate reached 50% after applying 10 high-voltage pulses. When gap A was 7 mm, the defoaming rate reached 3% after applying 10 high-voltage pulses. When gap A was 10 mm, the defoaming rate reached 1% after applying 10 high-voltage pulses. When gap A was 20 mm, the defoaming rate reached 0% after applying 10 high-voltage pulses.

[0035] The vertical axis on the right side of the graph in Figure 6 represents the energy of the pulse discharge (mJ / pulse). In the graph in Figure 6, the line L5 connecting the points plotted with "▲" indicates the energy of the pulse discharge at each gap. As can be seen from the graph in Figure 6, the shorter the gap A, the higher the discharge energy, and the longer the gap A, the lower the discharge energy. Therefore, if gap A is made too long, the discharge energy becomes too low and the bubbles cannot be destroyed. The discharge energy varies depending on the magnitude of the voltage. As can be seen from the results of this experiment, when the voltage is 27 kV, a gap A of approximately 3 mm to 10 mm is suitable.

[0036] In the next experiment, a state in which foam B was present on the liquid surface in tall beaker 30 was created in advance, and it was verified how many times high-voltage pulses had to be applied to completely destroy the stationary foam B. Figure 7 is a graph showing the relationship between the voltage of the high-voltage pulse and the number of applications of high-voltage pulse discharge. In the graph of Figure 7, the horizontal axis represents the voltage (kV) of the high-voltage pulse, and the vertical axis represents the number of applications of high-voltage pulse discharge. Gap A was set to 1 mm. The height of foam B from the liquid surface was set to 20 mm.

[0037] In this experiment, air and argon gas were used as the gases injected into the liquid. In the graph in Figure 4, line L6, connecting the dots plotted with "●," shows the results when air was injected into the liquid to form foam B, and line L7, connecting the dots plotted with "▲," shows the results when argon gas was injected into the liquid to form foam B. In the experiment where foam B was formed using air, the high-voltage pulse voltages were set to 15 kV, 16 kV, 17 kV, 19 kV, 21 kV, 23 kV, and 25 kV. In the experiment where foam B was formed using argon gas, the high-voltage pulse voltages were set to 8 kV, 13 kV, 16 kV, 18 kV, 20 kV, 22 kV, and 25 kV.

[0038] As can be seen from line L6 of the graph in Figure 7, when foam B was formed with air, the number of applications required to defoam all the foam when the voltage was 15 kV was 2,200, the number of applications required to defoam all the foam when the voltage was 16 kV was 1,500, the number of applications required to defoam all the foam when the voltage was 17 kV was 360, the number of applications required to defoam all the foam when the voltage was 19 kV was 227, the number of applications required to defoam all the foam when the voltage was 21 kV was 115, the number of applications required to defoam all the foam when the voltage was 23 kV was 37, and the number of applications required to defoam all the foam when the voltage was 25 kV was 12.

[0039] Similarly, as can be seen from line L7 of the graph in Figure 7, when foam B was formed with argon gas, the number of applications required to defoam all the foam when the voltage was 8 kV was 2,238, the number of applications required to defoam all the foam when the voltage was 13 kV was 354, the number of applications required to defoam all the foam when the voltage was 16 kV was 204, the number of applications required to defoam all the foam when the voltage was 18 kV was 160, the number of applications required to defoam all the foam when the voltage was 20 kV was 34, the number of applications required to defoam all the foam when the voltage was 22 kV was 16, and the number of applications required to defoam all the foam when the voltage was 25 kV was 8.

[0040] In addition, since rare gases such as argon gas are easier to generate discharges in than air, and since the generation of ozone can be suppressed by generating high-voltage pulse discharges in an atmosphere using argon gas, in this experiment argon gas was used to form foam B, and high-voltage pulse discharges were generated in argon gas.

[0041] As shown above, the higher the voltage, the fewer the number of times high-voltage pulse discharge was applied. For example, by using a high-voltage pulse of 15 kV and 200 Hz, air-based foam B could be completely destroyed in about 10 seconds. Also, by using a high-voltage pulse of 19 kV and 200 Hz, air-based foam B could be completely destroyed in about 1 second. This shows that the higher the voltage and frequency of the high-voltage pulse used, the more foam can be destroyed in a short period of time.

[0042] The defoaming device and defoaming method according to this embodiment can defoam using a power supply that generates a high voltage pulse and electrodes that generate a high voltage pulse discharge. Therefore, the defoaming device and defoaming method according to this embodiment can simplify the device configuration compared to defoaming using microwaves or laser light. Furthermore, the defoaming device according to this embodiment is composed of a power supply and electrodes. Since the defoaming device and the defoaming method according to the present embodiment are simple in configuration and have superior foam destruction power. Furthermore, since the defoaming device and the defoaming method according to the present embodiment do not use microwaves, it is possible to design an apparatus that does not require notification under the provisions of the Radio Law, since sound waves or ultrasonic waves are used for defoaming, and the foam destruction power is insufficient compared to when microwaves are used. With the defoaming device and the defoaming method according to the present embodiment, the foam destruction power can be increased as the high voltage pulse is made higher. With the defoaming device and the defoaming method according to the present embodiment, the foam destruction power is superior with a simple configuration. Furthermore, since the defoaming device and the defoaming method according to the present embodiment do not use microwaves, it is possible to design an apparatus that does not require notification under the provisions of the Radio Law.

[0043] Furthermore, in the foam decompression device and foam decompression method according to this embodiment, by setting the voltage of the high-voltage pulse to a high voltage, the foam B can be destroyed even when the high-voltage electrode 12A and the counter electrode 12B are placed away from the foam. For example, in the embodiment shown in FIG. 1, by setting the voltage of the high-voltage pulse to 50 kV to 100 kV, the foam B can be destroyed even when the high-voltage electrode 12A and the counter electrode 12B are placed above the liquid surface S and away from the foam B. For example, when the voltage of the high-voltage pulse is set to 100 kV, In this case, foam B can be destroyed even if gap A is set to about 60 mm. The defoaming device and defoaming method according to this embodiment are a defoaming technology that has a high degree of freedom in electrode arrangement and is easy to operate.

[0044] <Application example> The foam decompression device and foam decompression method according to the present embodiment can be applied to the nuclear fuel reprocessing process. By using the foam decompression device and foam decompression method to destroy the foam generated during the reprocessing process, it is possible to prevent the leakage and diffusion of contaminated foam. Furthermore, by using the foam decompression device and foam decompression method in a melting furnace, it is possible to prevent the unintended formation of an insulating layer.

[0045] An application example of the defoaming device and defoaming method according to this embodiment is defoaming in the vitrification process of high-level radioactive liquid waste. FIG. 8 is a cross-sectional view schematically showing a melting furnace 50 used in the vitrification process of high-level radioactive liquid waste. The melting furnace 50 has refractory bricks 52 assembled in a casing 51, and a furnace 53 formed therein. Molten glass 54 is supplied into the furnace 53 from a raw material supply device 55 at the top of the furnace 53. Main electrodes 56 are arranged around the periphery of the furnace 53, a bottom electrode 57 is arranged at the bottom of the furnace 53, and an indirect heater 58 is provided at the top of the furnace 53. The molten glass 54 is heated by the energized main electrode 56, bottom electrode 57, and indirect heater 58, and is in a high-temperature state.

[0046] High-level liquid waste is fed from a material feeder 55 into molten glass 54 in furnace 53. The high-level liquid waste is mixed with the molten glass 54 and poured into a canister 60 located at the outlet of furnace 53 through a downflow nozzle 59 at the bottom of furnace 53, where it is solidified in the next step of the reprocessing process.

[0047] During the vitrification process of high-level radioactive liquid waste, evaporation of water and decomposition of nitrates contained in the high-level liquid waste cause foam (not shown in FIG. 8 ) to form on the surface of the molten glass. This foam can be destroyed by the defoamer 10 according to this embodiment. For example, as shown in FIG. 8 , a high-voltage electrode 12A connected to a high-voltage pulse generator 11 via an electric wire 13 is inserted into a furnace 53 from a raw material supplier 55. A counter electrode 12B is also disposed within the furnace 53. The defoamer 10 generates a high-voltage pulse discharge between the high-voltage electrode 12A and the counter electrode 12B, thereby destroying the foam in the furnace 53. If foam develops in the melting furnace 50, it acts as an insulating layer and destabilizes the temperature control within the melting furnace 50. The defoamer and defoaming method according to this embodiment destroy the foam, thereby preventing the formation of an insulating layer.

[0048] <Other embodiments> Although the embodiments of the present disclosure have been described above, the various embodiments and modifications described above can be combined as much as possible. Although an example of breaking up bubbles has been described above, the present disclosure is not limited thereto. The defoaming device and defoaming method according to the present disclosure can also break up bubbles that form on a solid, for example. For example, when applying paint to a solid surface, the defoaming device and defoaming method according to the present disclosure can break up bubbles on the paint, thereby suppressing the occurrence of uneven paint coating.

[0049] Furthermore, the defoaming device and defoaming method according to the present disclosure can be widely applied to technologies for destroying foam that occurs on the surface of a liquid or solid, such as foam suppression during aeration (including ozone aeration) in wastewater or sludge treatment, foam suppression during metal extraction, and other foam suppression during chemical reactions. [Explanation of symbols]

[0050] 10...Defoaming device 11. Pulse generating section 11A pulse generator circuit 11B Pulse Compression Circuit 11C...Output electrode 12...Electrode part 12A High Voltage Electrode 12B: Opposite 13...Electric wire 20 High-voltage power supply 21 Thyristor 30··Tall Beaker 40··Air pump 41. Glass tube 50 Melting furnace 51 Casing 52 Firebrick 53...Furnace 54 Molten Glass 55...Raw material feeder 56...Main electrode 57...Bottom electrode 58 Indirect Heater 59 Flow Down Nozzle 60 canisters A Gap B. Foam S··Liquid level

Claims

1. a high-voltage pulse generating unit that generates a high-voltage pulse; an electrode unit having a high-voltage electrode to which the high-voltage pulse is applied from the high-voltage pulse generating unit and a counter electrode, and defoaming by generating a high-voltage pulse discharge between the high-voltage electrode and the counter electrode; A defoaming device comprising:

2. This is a state in which foam occurs on the surface of the liquid in the container. The high-voltage pulse generating unit increases the frequency of the high-voltage pulse as the rising speed of the foam increases, thereby forming an equilibrium state in which the upper surface of the foam does not rise. The defoaming device of claim 1.

3. The high voltage electrode and the liquid surface are not in contact with each other. The defoaming device according to claim 2.

4. the distance between the high voltage electrode and the liquid surface is 1 mm to 60 mm; The high-voltage pulse generating unit generates the high-voltage pulse of 3 kV or more. The defoaming device according to claim 2 or 3.

5. generating a high voltage pulse by a high voltage pulse generating unit; defoaming by generating a high-voltage pulse discharge between a high-voltage electrode to which the high-voltage pulse is applied from the high-voltage pulse generating unit and a counter electrode; A method for defoaming, comprising:

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