Nori seaweed freshness preservation system

Abstract

This system provides a freshness preservation system for raw nori seaweed that more reliably maintains its freshness, and consequently, enables further improvement in the quality (commercial value) of dried nori. [Solution] One end of a second seawater pumping hose 12, separate from the first seawater pumping hose 9, is located at the bottom of the water tank 5 of the stirring tank 2, and the other end of the second seawater pumping hose 12 is connected to the middle of the transfer hose 10 via an electrically operated three-way ball valve 13. The electrically operated three-way ball valve 13 is used to switch between a first flow path (a dedicated flow path for the preliminary stage before introducing new seaweed raw material into the stirring tank 2) that directly sends seawater from the water tank 5 of the stirring tank 2 to the high-concentration oxygen dissolving device (oxygen fighter) 3b without going through the buffer water tank 3a, and a second flow path that sends seawater from the water tank 5 of the stirring tank 2 to the high-concentration oxygen dissolving device (oxygen fighter) 3b via the buffer water tank 3a, before and after introducing new seaweed raw material into the stirring tank 2.

Description

Technical Field

[0001] The present invention relates to a freshness maintenance system for seaweed thallus used to maintain the freshness of seaweed thallus during the production of dried seaweed.

Background Art

[0002] The production of dried seaweed is carried out in the following procedure. First, the harvested seaweed thallus is immediately transferred (put in) into a stirring tank filled with seawater after landing and stored while being stirred. This seaweed thallus is washed, shredded, and then blended with water to become a seaweed raw material. Next, this seaweed raw material goes through the processes of papermaking → pressing and dehydration → drying → peeling to become dried seaweed.

[0003] However, when the seaweed thallus is stored in the stirring tank for a long time, the oxygen concentration of the seawater stored together with the seaweed thallus decreases. And because of this, there is a problem that the freshness of the seaweed thallus decreases, and ultimately the quality of the dried seaweed decreases.

[0004] Therefore, the present applicant has previously proposed a freshness maintenance system for seaweed thallus that can surely maintain the freshness of seaweed thallus without increasing the cost of equipment, and ultimately improve the quality (commercial value) of dried seaweed (see Patent Documents 1 and 2).

[0005] The freshness maintenance system for seaweed thallus proposed in Patent Documents 1 and 2 is a freshness maintenance system for seaweed thallus used to maintain the freshness of seaweed thallus during the production of dried seaweed, which stores the seaweed thallus together with seawater and stirs it, and a stirring tank, and a gas-liquid mixing device that dissolves oxygen in seawater at a predetermined pressure to obtain seawater containing a high concentration of dissolved oxygen, and seawater input means for inputting the seawater containing the high concentration of dissolved oxygen into the stirring tank. Here, the gas-liquid mixing device is composed of a temporary storage tank for temporarily storing seawater and a high-concentration oxygen dissolution device combined.

[0006] Furthermore, a freshness preservation system for raw nori seaweed equipped with such a configuration includes a gas-liquid mixing device that dissolves oxygen in seawater at a predetermined pressure to obtain seawater containing a high concentration of dissolved oxygen. Since the seawater containing a high concentration of dissolved oxygen obtained from the gas-liquid mixing device is introduced into a stirring tank, it is possible to prevent a decrease in the oxygen concentration of the seawater stored in the stirring tank together with the raw nori seaweed. Therefore, a freshness preservation system for raw nori seaweed with such a configuration can reliably maintain the freshness of raw nori seaweed without increasing equipment costs, and consequently, improve the quality (commercial value) of dried nori. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2023-114994 [Patent Document 2] Japanese Patent Publication No. 2024-031392 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, by the time new seaweed is harvested, brought ashore, and transported to a mixing tank filled with seawater, the new seaweed has almost completely consumed the dissolved oxygen in the seawater (the dissolved oxygen concentration drops drastically to nearly 0 mg / L). Therefore, if a freshness preservation system for raw nori seaweed proposed in Patent Documents 1 and 2 is implemented, in which new raw nori seaweed is transferred (added) to a stirring tank containing seawater, oxygen is dissolved in the seawater at a predetermined pressure to obtain seawater containing a high concentration of dissolved oxygen, and this seawater containing a high concentration of dissolved oxygen is then added to the stirring tank, the dissolved oxygen concentration in the stirring tank will drop sharply immediately after the new raw nori seaweed is added (due to the consumption of dissolved oxygen by the new raw nori seaweed, the dissolved oxygen concentration will instantly drop from the initial 7-8 mg / L (approximately 7.5 mg / L) to 0 mg / L), and it will take some time for the new raw nori seaweed being transferred (added) to the stirring tank to be filled with seawater containing a high concentration of dissolved oxygen. In other words, the freshness maintenance systems for raw nori seaweed proposed in Patent Documents 1 and 2 do have the effect of "reliably maintaining the freshness of raw nori seaweed and, consequently, improving the quality (commercial value) of dried nori," but there is a time lag between when new raw nori seaweed is transferred (added) to the mixing tank and when this effect is realized. Therefore, there is a risk of the raw nori seaweed losing its freshness in the initial stages after it is added to the mixing tank. To avoid this risk, it becomes necessary to adjust the time and quantity between the unloading of new raw nori seaweed and its addition to the mixing tank.

[0009] Therefore, the inventors diligently conducted research to solve these problems and found that by providing a dedicated channel for obtaining seawater containing a high concentration of dissolved oxygen in a short time and through the shortest possible flow path, prior to the stage in which new seaweed raw material is introduced into the stirring tank, it is possible to reliably avoid the "risk of deterioration of the freshness of the seaweed raw material" in the initial stage after the new seaweed raw material is introduced into the stirring tank, thus completing the present invention.

[0010] This invention was made to solve the above problems and aims to provide a freshness maintenance system for raw nori seaweed that can more reliably maintain the freshness of the raw nori seaweed, and thereby further improve the quality (commercial value) of dried nori seaweed. [Means for solving the problem]

[0011] To achieve the above objective, the configuration of the nori raw seaweed freshness maintenance system according to the present invention is as follows: (1) A system for maintaining the freshness of raw seaweed used in the production of dried seaweed, A stirring tank for storing and agitating the aforementioned raw seaweed together with seawater, A gas-liquid mixing apparatus that dissolves oxygen in seawater at a predetermined pressure to obtain seawater containing a high concentration of dissolved oxygen, A seawater input means for introducing the aforementioned seawater containing a high concentration of dissolved oxygen into the stirring tank, Equipped with, The gas-liquid mixing apparatus is configured by combining a temporary storage tank for temporarily storing seawater and a high-concentration oxygen dissolution apparatus, and has a first channel (dedicated channel) that directly supplies seawater to the high-concentration oxygen dissolution apparatus without going through the temporary storage tank, and a second channel that supplies seawater to the high-concentration oxygen dissolution apparatus via the temporary storage tank. The first channel (dedicated channel) and the second channel are characterized in that they can be switched before and after the raw seaweed is introduced into the stirring tank.

[0012] The configuration of (1) above for the freshness maintenance system for raw nori seaweed of the present invention provides the following effects. In other words, according to the configuration of (1) above, by using the first channel (dedicated channel) in the stage before introducing new seaweed into the mixing tank, seawater can be sent directly to the high-concentration oxygen dissolving device without going through a temporary storage tank, thereby obtaining seawater containing a high concentration of dissolved oxygen in a short time and in the shortest channel. This seawater containing a high concentration of dissolved oxygen can then be introduced into the mixing tank, thereby increasing the dissolved oxygen concentration of the seawater stored in the mixing tank. As a result, the new seaweed being transferred (introduced) into the mixing tank is instantly filled with seawater containing a high concentration of dissolved oxygen, making it possible to supply the seaweed with oxygen that was insufficient when it was introduced into the mixing tank. Therefore, the risk of "deterioration of the freshness of the seaweed" in the initial stage after introducing new seaweed into the mixing tank can be reliably avoided. Therefore, according to the configuration of (1) above, it is possible to provide a freshness maintenance system for raw nori seaweed that can more reliably maintain the freshness of the raw nori seaweed and, consequently, further improve the quality (commercial value) of dried nori seaweed.

[0013] In the configuration of the seaweed raw material freshness maintenance system of the present invention described in (1) above, it is preferable to have the following configuration as described in (2).

[0014] (2) In the configuration of (1) above, when the first flow path is used, the high-concentration oxygen dissolution device is controlled at high speed to increase the flow rate of seawater sent to the high-concentration oxygen dissolution device. When using the second flow path, the high-concentration oxygen dissolution device is controlled at a low speed to reduce the flow rate of seawater supplied to the device.

[0015] According to the preferred configuration of (2) above, first, before introducing new seaweed spores into the stirring tank, it becomes possible to obtain seawater containing a fairly high concentration of dissolved oxygen in a short time and through the shortest flow path, and it becomes possible to more reliably avoid the "risk of causing a decrease in the freshness of the seaweed spores" in the initial stage after introducing the new seaweed spores into the stirring tank. Further, after the new seaweed spores are introduced into the stirring tank, for example, it becomes possible to take in seawater while reducing the clogging of the seaweed spores in the punching metal.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a freshness maintenance system for seaweed spores that can more reliably maintain the freshness of seaweed spores, and thus further improve the quality (commercial value) of dried seaweed.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a schematic layout diagram showing the configuration of a freshness maintenance system for seaweed spores in an embodiment of the present invention. [Figure 2] FIG. 2 is a photographic perspective view showing the state around a stirring tank, which is a component of a freshness maintenance system for seaweed spores in an embodiment of the present invention.

Modes for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described more specifically using preferred embodiments. However, the following embodiments are merely examples embodying the present invention, and the present invention is not limited thereto.

[0019] (Basic Configuration of Freshness Maintenance System for Seaweed Spores) First, the basic configuration of a freshness maintenance system for seaweed spores in an embodiment of the present invention will be described with reference to FIGS. 1 to 2.

[0020] Figure 1 is a schematic layout diagram showing the configuration of a system for maintaining the freshness of raw seaweed in one embodiment of the present invention, and Figure 2 is a photographic perspective view showing the area around the stirring tank, which is a component of the system for maintaining the freshness of raw seaweed.

[0021] The freshness preservation system for raw nori seaweed (hereinafter also simply referred to as the "freshness preservation system") 1 of this embodiment, shown in Figures 1 and 2, is used to maintain the freshness of raw nori seaweed during the production of dried nori. As shown in Figures 1 and 2, the freshness preservation system 1 comprises a roughly rectangular stirring tank 2 for storing and stirring raw nori seaweed together with seawater, a gas-liquid mixing device 3 for dissolving oxygen in seawater at a predetermined pressure to obtain seawater containing a high concentration of dissolved oxygen (DO) (hereinafter also simply referred to as "high-DO concentration seawater"), and a seawater input means 4 for introducing the high-DO concentration seawater into the stirring tank 2. Here, the "specified pressure" is, for example, approximately 0.2 MPa.

[0022] According to the freshness preservation system 1 of this embodiment, which has the above configuration, a gas-liquid mixing device 3 is provided that dissolves oxygen in seawater at a predetermined pressure to obtain seawater with a high DO concentration, and the high DO concentration seawater obtained by the gas-liquid mixing device 3 is put into the stirring tank 2, thereby preventing a decrease in the oxygen concentration of the seawater stored in the stirring tank 2 together with the raw seaweed. Therefore, according to the freshness preservation system 1 of this embodiment, which has such a configuration, it is possible to reliably maintain the freshness of raw nori seaweed and, consequently, improve the quality (commercial value) of dried nori.

[0023] Further details are provided below. As shown in Figures 1 and 2, the stirring tank 2 has a stirring blade 2a for stirring the raw nori seaweed with seawater, a rotating shaft 2b for rotating the stirring blade 2a, and a motor (not shown) for rotating the rotating shaft 2b. The stirring blade 2a can be of an appropriate shape, such as a turbine blade, paddle blade, or propeller blade. The stirring tank 2 is provided with a water tank (triangular corner) 5 in one of its four corners, which separates the raw nori seaweed so that seawater can flow through it. A dissolved oxygen meter (DO meter) 6 is installed in the water tank 5, and the DO meter 6 measures the dissolved oxygen concentration (DO concentration) in the stirring tank 2 and is linked to the seawater intake pump 3c, which will be described later. The operation of the seawater intake pump 3c is controlled by the DO concentration in the stirring tank 2. Furthermore, a water level gauge 7 is installed in the water tank 5, and the water level gauge 7 detects the water level in the water tank 5 and is linked to the seawater intake pump 3c and the oxygen dissolution pump 3d, which will be described later. Furthermore, the operation of the seawater intake pump 3c and the oxygen dissolution pump 3d is controlled by the water level in the water tank 5 of the stirring tank 2. A float-type water level gauge is used as the water level gauge 7.

[0024] More specifically, the tank 5 has a right-angled isosceles triangular tubular shape with at least its top end open (triangular corner), and two sides that abut against the two inner corners (inner surfaces) of the mixing tank 2 are made of stainless steel plates, while the other side that does not abut against the inner surface of the mixing tank 2 is made of porous stainless steel perforated metal 5a. This perforated metal 5a functions as a filter to draw up only seawater from inside the mixing tank 2, preventing the drawing up of seaweed. The water tank (triangular corner) 5 is detachably attached to the mixing tank 2, and by removing it from the mixing tank 2, the raw seaweed that has accumulated in the perforated metal 5a can be easily removed. Furthermore, the hole diameter of the perforated metal 5a is not limited to a specific size, as long as it is large enough to prevent seaweed from passing through. The current hole diameter (φ) is approximately 1.0 mm. Also, the perforated metal 5a has a width (W) of approximately 680 mm, a height (H) of approximately 2700 mm, and a hole pitch of approximately 1.0 mm.

[0025] As described above, the DO meter 6 is installed inside the tank 5. By installing the DO meter 6 inside the tank 5, the DO concentration can be measured without interference from the seaweed.

[0026] One end of the first seawater pumping hose 9 is located at the bottom of the water tank 5 of the stirring tank 2. The other end of the first seawater pumping hose 9 is located in the buffer water tank 3a, which will be described later. A seawater intake pump 3c is installed in the middle of the first seawater pumping hose 9. When the seawater intake pump 3c starts operating, the pumping of seawater into the buffer tank 3a begins, and when the seawater intake pump 3c stops operating, the pumping of seawater into the buffer tank 3a stops. The flow rate of seawater pumped from the tank 5 of the stirring tank 2 to the buffer tank 3a is measured by a flow meter (not shown).

[0027] The gas-liquid mixing device 3 for obtaining seawater containing a high concentration of dissolved oxygen (high-DO concentration seawater) is composed of a buffer water tank (storage tank) 3a as a temporary storage tank and a high-concentration oxygen dissolution device 3b. In this device, the Oxygen Fighter (registered trademark) manufactured by Daiei Seisakusho Co., Ltd. is used as the high-concentration oxygen dissolution device 3b.

[0028] Buffer tank 3a is for temporarily storing seawater pumped up from tank 5 of agitation tank 2. A water level gauge 8 is installed in the buffer tank (water storage tank) 3a. This water level gauge 8 detects the water level in the buffer tank 3a and is linked to the seawater intake pump 3c, the oxygen dissolution pump 3d (described later), and the gas-liquid mixing device 3. The operation of the seawater intake pump 3c, the oxygen dissolution pump 3d, and the gas-liquid mixing device 3 is controlled by the water level in the buffer tank 3a. A float-type water level gauge 8 is used.

[0029] The high-concentration oxygen dissolution device (oxygen fighter) 3b is equipped with an oxygen dissolution pump 3d for supplying seawater from the buffer tank 3a into the oxygen gas within the device. One end of a transfer hose 10 is connected to the buffer tank 3a, and the other end of the transfer hose 10 is connected to the suction port of the oxygen dissolution pump 3d. By changing the frequency with an inverter 3e, the rotation speed (velocity) of the motor (not shown) of the oxygen dissolution pump 3d can be switched to adjust the flow rate of seawater supplied to the high-concentration oxygen dissolution device (oxygen fighter) 3b. Furthermore, the oxygen gas in the high-concentration oxygen dissolution device (oxygen fighter) 3b is supplied to the device using an oxygen gas cylinder (not shown). The supply pressure is, for example, approximately 0.2 MPa. The frequency of the inverter 3e is changed by operating a switch on the inverter control panel (not shown).

[0030] Seawater containing high concentrations of dissolved oxygen (high-DO concentration seawater) can be obtained as follows. Specifically, oxygen gas is supplied to the high-concentration oxygen dissolving device (oxygen fighter) 3b at a predetermined pressure (for example, about 0.2 MPa), and then seawater from the buffer tank 3a is introduced into the oxygen gas within the high-concentration oxygen dissolving device (oxygen fighter) 3b. By passing seawater through the oxygen, oxygen dissolves into the seawater at a high concentration, resulting in seawater with a high DO concentration.

[0031] The high-DO concentration seawater in the high-concentration oxygen dissolution device (oxygen fighter) 3b is introduced into the stirring tank 2 by the seawater input means 4, as described above. The seawater injection means 4 consists of the oxygen dissolution pump 3d described above, which also functions as a circulation pump, and a seawater injection hose 4a, one end of which is connected to the discharge port of the high-concentration oxygen dissolution device (oxygen fighter) 3b. The other end of the seawater injection hose 4a is positioned along the inner surface of the stirring tank 2 so as not to interfere with the stirring blades 2a. The tip of the other end of the seawater injection hose 4a is positioned at the bottom outside the water tank 5 of the stirring tank 2.

[0032] A three-way ball valve 11 is installed in the middle of the seawater inlet hose 4a. The three-way ball valve 11 is for directing the incoming high-DO concentration seawater to either one of the two seawater inlet hoses (the other end of one seawater inlet hose 4a is located at the bottom outside the tank 5 of the agitation tank 2 as described above, and the other end of the other seawater inlet hose is located inside another tank (for example, a seawater tank for storing seawater, another agitation tank, etc.)) or for splitting the flow to both seawater inlet hoses.

[0033] In this embodiment, as described above, high-DO concentration seawater is introduced into the bottom outside of the water tank 5 of the stirring tank 2. With this configuration, the following effects can be obtained. In other words, when high-DO concentration seawater is introduced into tank 5, the seaweed bedrock may obstruct the flow of the high-DO concentration seawater through the perforated metal 5a to areas of the stirring tank 2 other than tank 5. In contrast, by introducing high-DO concentration seawater to the bottom outside of the tank 5 of the stirring tank 2, the high-DO concentration seawater can easily diffuse throughout the stirring tank 2, making it possible to reliably maintain the freshness of the nori seaweed.

[0034] (Switching the flow path of seawater before and after introducing new seaweed into the mixing tank) Next, the switching of the seawater flow path before and after introducing new seaweed raw material into the stirring tank in this embodiment will be explained with reference to Figure 1. Here, "seawater flow path" more specifically refers to the "seawater intake route" from the water tank 5 of the stirring tank 2 to the intake port of the oxygen dissolution pump 3d.

[0035] As shown in Figure 1, one end of a second seawater pumping hose 12, separate from the first seawater pumping hose 9, is located at the bottom of the water tank 5 of the stirring tank 2. The other end of the second seawater pumping hose 12 is connected to the middle of the transfer hose 10 via a three-way ball valve 13. The three-way ball valve 13 is used to switch between a first flow path (a dedicated flow path for the preliminary stage before introducing new seaweed to the mixing tank 2) that directly sends seawater from tank 5 of the mixing tank 2 to the high-concentration oxygen dissolution device (oxygen fighter) 3b without going through the buffer tank 3a, and a second flow path that sends seawater from tank 5 of the mixing tank 2 to the high-concentration oxygen dissolution device (oxygen fighter) 3b via the buffer tank 3a, before and after introducing new seaweed to the mixing tank 2. The three-way ball valve 13 is equipped with an electric actuator 14 that has a control motor (electric three-way ball valve). The electric three-way ball valve 13 works in conjunction with the control system and operates in response to external instructions and control signals. That is, the switching between the first flow path (dedicated flow path) and the second flow path is performed automatically by the electric three-way ball valve 13 in response to instructions and control signals from an external source (for example, an operator). With this configuration, manual switching between the first flow path (dedicated flow path) and the second flow path is unnecessary, contributing to labor savings.

[0036] A three-way ball valve 15 is provided in the middle of the transfer hose 10, positioned between the electrically operated three-way ball valve 13 and the suction port of the oxygen dissolution pump 3d. The three-way ball valve 15 is used to directly send seawater taken from other tanks (for example, a seawater tank for storing seawater, another mixing tank, etc.) to the high-concentration oxygen dissolution device (oxygen fighter) 3b without going through the buffer tank 3a, in the stage before new seaweed raw material is put into the stirring tank 2 (use of the high-concentration oxygen dissolution device (oxygen fighter) 3b alone). Furthermore, if seawater taken from another tank or the like is sent directly to the high-concentration oxygen dissolution device (oxygen fighter) 3b without passing through the buffer tank 3a before new seaweed raw material is added to the stirring tank 2, the electric three-way ball valve 13 will be in a closed state. Also, if seawater from the buffer tank 3a is sent to the high-concentration oxygen dissolution device (oxygen fighter) 3b after new seaweed raw material has been added to the stirring tank 2, the three-way ball valve 15 will be in an open state, moving from the electric three-way ball valve 13 toward the suction port of the oxygen dissolution pump 3d.

[0037] The reason for switching the seawater flow path before and after adding new seaweed to the mixing tank 2 is that, in the stage before adding new seaweed to the mixing tank 2, it is necessary to produce high-DO concentration seawater in a short time and with the shortest possible flow path. More specifically, it is necessary to produce high-DO concentration seawater from the moment the seaweed in the mixing tank 2 is depleted until the seaweed comes out of the dryer.

[0038] Furthermore, by switching the flow path of seawater before and after introducing new seaweed into the mixing tank 2, the following effects can be obtained. In other words, by switching to the first channel (dedicated channel) before introducing new seaweed into the mixing tank 2, seawater from tank 5 of the mixing tank 2 is sent directly to the high-concentration oxygen dissolving device (oxygen fighter) 3b without going through the buffer tank 3a, thereby obtaining high-DO concentration seawater in a short time and through the shortest channel. This high-DO concentration seawater is then introduced into the mixing tank 2, increasing the DO concentration of the seawater stored in the mixing tank 2. As a result, the new seaweed being transferred (introduced) into the mixing tank 2 is instantly filled with high-DO concentration seawater, providing the seaweed with the oxygen that was lacking when it was introduced into the mixing tank 2. Therefore, the risk of "deterioration of the freshness of the seaweed" in the initial stages after introducing new seaweed into the mixing tank 2 can be reliably avoided. Therefore, by switching the flow path of seawater before and after introducing new seaweed raw material into the stirring tank 2, it becomes possible to more reliably maintain the freshness of the seaweed raw material, and consequently, to further improve the quality (commercial value) of the dried seaweed.

[0039] (Adjusting the flow rate of seawater before and after adding new seaweed to the mixing tank) Next, we will explain how to adjust the flow rate of seawater before and after adding new seaweed to the stirring tank in this embodiment.

[0040] The reason for adjusting the flow rate of seawater before and after adding new raw nori seaweed to mixing tank 2 is as follows: In other words, as mentioned above, by the time new seaweed is harvested, brought ashore, and transported to the mixing tank 2 containing seawater, the new seaweed has almost completely consumed the dissolved oxygen in the seawater (the dissolved oxygen concentration drops drastically to almost 0 mg / L). Therefore, before introducing the new seaweed into the mixing tank 2, it is necessary to prepare seawater containing a fairly high concentration of dissolved oxygen in a short time and via the shortest possible flow path. Furthermore, after the addition of seaweed, the seaweed enters the mixing tank 2, causing the perforated metal 5a to become clogged with seaweed, making it difficult to take in seawater through the perforated metal 5a. Therefore, if the intake flow rate is approximately the same as the inflow rate of seawater, it becomes possible to take in seawater while reducing clogging of the perforated metal 5a with seaweed. Field analysis has revealed that the flow rate (seawater inflow rate) when seawater flows into the tank (triangular corner) 5 through the perforated metal 5a after new seaweed is added to the mixing tank 2 is approximately 33.5 to 43.3 L / min.

[0041] (A) Flow rate of seawater before adding new seaweed to the stirring tank For example, if the required amount of seawater before introducing new raw nori seaweed into the mixing tank is Xt, it is desirable that the oxygen dissolution pump 3d deliver the seawater in the tank 5 of the mixing tank 2 into the oxygen gas in the high-concentration oxygen dissolution device (oxygen fighter) 3b at a flow rate of approximately 13.3 XL / min. This desirable flow rate can be achieved by selecting the switch on the inverter control panel to "before introducing raw nori seaweed," setting the frequency of the inverter 3e to 60 Hz, and controlling the motor of the oxygen dissolution pump 3d at high speed.

[0042] In this way, by sending seawater from tank 5 of the stirring tank 2 into the oxygen gas in the high-concentration oxygen dissolving device (oxygen fighter) 3b at a flow rate of approximately 13.3 XL / min to obtain high-DO concentration seawater, and then introducing this high-DO concentration seawater into the stirring tank 2, the initial DO concentration in the stirring tank 2 (7-8 mg / L (approximately 7.5 mg / L)) can be increased to 30-40 mg / L by circulating it for about 2 hours. As a result, the new seaweed raw material transferred (introduced) into the stirring tank 2 is instantly filled with high-DO concentration seawater with an DO concentration of 30-40 mg / L, making it possible to supply the seaweed raw material with oxygen that was insufficient when introduced into the stirring tank 2. Therefore, the risk of "deterioration of the freshness of the seaweed raw material" in the initial stage after introducing new seaweed raw material into the stirring tank 2 can be more reliably avoided.

[0043] (B) Flow rate of seawater after new seaweed raw material is added to the stirring tank As described above, on-site analysis revealed that the flow rate (seawater inflow) when seawater flows into the tank (triangular corner) 5 through the perforated metal 5a after new seaweed raw material is introduced into the mixing tank 2 is approximately 33.5 to 43.3 L / min. At the time this value was obtained, the hole diameter (φ) of the perforated metal 5a was approximately 1.0 mm, the hole pitch was approximately 1.5 mm, the width (W) was approximately 680 mm, and the height (H) was approximately 2700 mm. While these values ​​were obtained through on-site analysis, if the intake flow rate is approximately the same as the seawater inflow rate, it is possible to take in seawater while reducing clogging of the perforated metal 5a with seaweed raw material. Therefore, it is desirable to set the intake flow rate to a value close to YL / min, in accordance with the seawater inflow rate YL / min, which is determined by the hole diameter (φ), pitch, surface area, etc., of the perforated metal 5a, as well as the amount of seaweed raw material and seawater introduced. Based on the above, in field analysis, it is desirable that the seawater intake pump 3c pump seawater from the tank 5 of the stirring tank 2 to the buffer tank 3a at a flow rate of approximately 35 L / min. Furthermore, it is desirable that the oxygen dissolution pump 3d send seawater from the buffer tank 3a into the oxygen gas in the high-concentration oxygen dissolution device (oxygen fighter) 3b at a flow rate of approximately 40 L / min. This desirable flow rate of approximately 40 L / min can be obtained by selecting the switch on the inverter control panel as "after adding raw seaweed," setting the frequency of the inverter 3e to 18 Hz, and controlling the motor of the oxygen dissolution pump 3d at a low speed. These values ​​are determined by the hole diameter and pitch of the perforated metal 5a, its surface area, etc., and the amount of raw seaweed and seawater added, and are not limited to the values ​​above.

[0044] (Operation of the system for maintaining the freshness of raw nori seaweed) Next, the operation of the nori seaweed freshness maintenance system 1 in this embodiment will be explained with reference to Figure 1.

[0045] (A) Operation before adding new seaweed to the stirring tank (using high-concentration oxygen dissolving device (oxygen fighter) 3b alone) First, the seawater intake route is switched from the second channel to the first channel (dedicated channel). More specifically, the switch from the second channel to the first channel (dedicated channel) is performed automatically by the electrically operated three-way ball valve 13 in response to instructions or control signals from an external source (operator). In this case, the three-way ball valve 15 is open in the direction from the electrically operated three-way ball valve 13 toward the suction port of the oxygen dissolution pump 3d.

[0046] Next, the oxygen dissolution pump 3d and the high-concentration oxygen dissolution device (oxygen fighter) 3b start operating. In this case, by selecting the switch on the inverter control panel to "before adding raw seaweed," the frequency of the inverter 3e is set to 60Hz, and the motor of the oxygen dissolution pump 3d, which also functions as a circulation pump, is controlled at high speed. Then, oxygen gas is supplied to the high-concentration oxygen dissolution device (oxygen fighter) 3b at a predetermined pressure (for example, about 0.2MPa), and then seawater from the water tank 5 of the stirring tank 2 is sent into the oxygen gas in the high-concentration oxygen dissolution device (oxygen fighter) 3b at a flow rate of about 130L / min. As a result, by passing seawater through the oxygen, oxygen dissolves in the seawater at a high concentration, and high-DO concentration seawater is obtained. When the water level detected by the water level gauge 7 installed in the water tank 5 of the stirring tank 2 reaches a predetermined level, the operation of the oxygen dissolution pump 3d stops.

[0047] Next, the oxygen dissolution pump 3d, which also functions as a circulation pump, is restarted. Then, the high-DO concentration seawater in the high-concentration oxygen dissolution device (oxygen fighter) 3b is introduced to the bottom outside of the water tank 5 of the stirring tank 2 by the seawater input means 4. By circulating this series of operations for about 2 hours, the initial DO concentration in the stirring tank 2 (7-8 mg / L (approximately 7.5 mg / L)) is increased to 30-40 mg / L.

[0048] Furthermore, when using the high-concentration oxygen dissolution device (oxygen fighter) 3b alone, seawater taken from other tanks (for example, a seawater tank for storing seawater, another agitation tank, etc.) may be directly introduced into the oxygen gas inside the high-concentration oxygen dissolution device (oxygen fighter) 3b without going through the three-way ball valve 15 (Figure 1).

[0049] (B) Operation after adding new seaweed to the stirring tank The newly harvested seaweed is immediately transferred (added) to a stirring tank 2 containing seawater after being brought ashore, and stored while being stirred. At this time, the initial DO concentration in the stirring tank 2 is increased to 30-40 mg / L as described above. In this way, by maintaining a high initial DO concentration of 30-40 mg / L in the mixing tank 2, the new seaweed raw material transferred (added) to the mixing tank 2 is instantly filled with high-DO concentration seawater of 30-40 mg / L, making it possible to supply the seaweed raw material with oxygen that was lacking when it was added to the mixing tank 2. As a result, it is possible to reliably avoid the risk of "deterioration of the freshness of the seaweed raw material" in the initial stages after the new seaweed raw material is added to the mixing tank 2. However, even with this, if the raw nori seaweed is stored in the stirring tank 2 for a long period of time, the oxygen concentration of the seawater stored with the nori seaweed will decrease. Therefore, if this continues, there is a risk that the freshness of the nori seaweed will deteriorate.

[0050] In this freshness preservation system 1, the freshness of the raw nori seaweed is maintained in the following manner. After new seaweed raw material is introduced into the mixing tank 2, the seawater intake route is first switched from the first channel (dedicated channel) to the second channel. More specifically, the switch from the first channel (dedicated channel) to the second channel is performed automatically by the electrically operated three-way ball valve 13 in response to instructions or control signals from an external source (operator). In this case, the three-way ball valve 15 is open in the direction from the electrically operated three-way ball valve 13 toward the intake port of the oxygen dissolution pump 3d.

[0051] Next, when the DO concentration measured by the DO meter 6 installed in the tank 5 of the stirring tank 2 falls below a predetermined threshold of less than 7.5 mg / L, and the water level detected by the water level gauge 7 installed in the tank 5 of the stirring tank 2 is at a predetermined level, the seawater intake pump 3c is started to operate. This starts the pumping of seawater from the tank 5 of the stirring tank 2 to the buffer tank 3a (flow rate approximately 35 L / min).

[0052] Next, when the water level detected by the water level gauge 8 installed in the buffer tank 3a reaches a predetermined level, the operation of the seawater intake pump 3c is stopped. Next, the oxygen dissolution pump 3d and the gas-liquid mixing device 3 are started. In this case, by selecting the switch on the inverter control panel to "after adding raw seaweed," the frequency of the inverter 3e is set to 18Hz, and the motor of the oxygen dissolution pump 3d, which also functions as a circulation pump, is controlled at a low speed. Then, oxygen gas is supplied to the high-concentration oxygen dissolution device (oxygen fighter) 3b at a predetermined pressure (for example, about 0.2MPa), and then seawater from the buffer tank 3a is sent into the oxygen gas in the high-concentration oxygen dissolution device (oxygen fighter) 3b at a flow rate of about 40L / min. As a result, by passing seawater through the oxygen, oxygen is dissolved in the seawater at a high concentration, and high-DO concentration seawater is obtained. When the water level detected by the water level gauge 8 installed in the buffer tank 3a reaches a predetermined level, the operation of the oxygen dissolution pump 3d is stopped.

[0053] Next, the oxygen dissolution pump 3d, which also functions as a circulation pump, is restarted. Then, the high-DO concentration seawater in the high-concentration oxygen dissolution device (oxygen fighter) 3b is introduced to the bottom outside of the tank 5 of the stirring tank 2 by the seawater input means 4. As a result, the DO concentration in the stirring tank 2 settles at approximately 7.5 mg / L, maintaining the freshness of the nori seaweed.

[0054] As explained above, after new seaweed raw material is introduced into the mixing tank 2, the freshness maintenance system 1 operates as needed according to the DO concentration in the mixing tank 2, and high-DO concentration seawater is circulated and introduced (supplied) to the bottom outside of the water tank 5 of the mixing tank 2. This makes it possible to maintain the freshness of the seaweed raw material for a long time, contributing to the maintenance of the quality (commercial value) of the dried seaweed.

[0055] Furthermore, after new seaweed raw material has been added to the stirring tank 2, high-DO concentration seawater, which has been diverted by a three-way ball valve 11 (Figure 1) and stored in other tanks (for example, a seawater tank for storing seawater, or another stirring tank), can be injected into the stirring tank 2 containing the new seaweed raw material as needed.

[0056] In this embodiment, the example given is that seawater for obtaining high-DO concentration seawater is pumped up (taken) from the stirring tank 2. However, the present invention is not necessarily limited to this configuration. For example, high-DO concentration seawater may be obtained using seawater pumped up (taken) from a seawater tank or the like for storing seawater separate from the seawater in the stirring tank 2. More specifically, high-DO concentration seawater may be obtained by sending seawater pumped up (taken) from a seawater tank for storing seawater, another stirring tank, etc., into the oxygen gas in the high-concentration oxygen dissolution device (oxygen fighter) 3b via a three-way ball valve 15 (Figure 1). Alternatively, high-DO concentration seawater may be obtained by sending seawater pumped up (taken) from a seawater tank for storing seawater, another stirring tank, etc., into the oxygen gas in the high-concentration oxygen dissolution device (oxygen fighter) 3b via a buffer water tank 3a.

[0057] Furthermore, in this embodiment, the gas-liquid mixing device 3 for obtaining high-DO concentration seawater was described as a combination of a buffer water tank 3a as a temporary storage tank and an Oxygen Fighter (registered trademark) manufactured by Daiei Seisakusho Co., Ltd. as a high-concentration oxygen dissolving device 3b. However, the present invention is not necessarily limited to this configuration. As long as high-DO concentration seawater can be obtained, a device other than the Oxygen Fighter (registered trademark) may be used as the high-concentration oxygen dissolving device.

[0058] Furthermore, in this embodiment, the water tank 5 has a right-angled isosceles triangular tubular shape with at least its upper end open (triangular corner), and two sides that abut against two inner corners (inner surfaces) of the stirring tank 2 are made of stainless steel plates, while the other side that does not abut against the inner surface of the stirring tank 2 is made of porous plate-shaped stainless steel perforated metal 5a. However, the present invention is not necessarily limited to this configuration. The water tank may be formed, for example, by fixing a porous plate-shaped stainless steel perforated metal to one of the four corners inside the stirring tank 2. [Explanation of Symbols]

[0059] 1. System for maintaining the freshness of raw nori seaweed 2. Agitation tank 2a stirring blade 2b Rotation axis 3 Gas-liquid mixing device 3a Buffer tank (water storage tank) 3b High-concentration oxygen dissolution device (Oxygen Fighter) 3c Seawater intake pump 3D oxygen dissolution pump 3e Inverter 4 Seawater injection means 4a Seawater injection hose 5 Aquariums 5a Perforated metal 6. Dissolved oxygen meter (DO meter) 7,8 Water level gauge 9. No. 1 seawater pumping hose 10 Transfer hoses 11,15 Three-way ball valve 12. Second seawater pumping hose 13. Electric three-way ball valve 14 Electric Actuator

Claims

1. A system for maintaining the freshness of raw seaweed used in the production of dried seaweed, A stirring tank for storing and agitating the aforementioned raw seaweed together with seawater, A gas-liquid mixing apparatus that dissolves oxygen in seawater at a predetermined pressure to obtain seawater containing a high concentration of dissolved oxygen, A seawater input means for introducing the aforementioned seawater containing a high concentration of dissolved oxygen into the stirring tank, Equipped with, The gas-liquid mixing apparatus is configured by combining a temporary storage tank for temporarily storing seawater and a high-concentration oxygen dissolving apparatus, and has a first flow path that directly supplies seawater to the high-concentration oxygen dissolving apparatus without going through the temporary storage tank, and a second flow path that supplies seawater to the high-concentration oxygen dissolving apparatus via the temporary storage tank. A system for maintaining the freshness of raw nori seaweed, characterized in that the first flow path and the second flow path can be switched before and after the raw nori seaweed is introduced into the stirring tank.

2. When using the first flow path, the high-concentration oxygen dissolution device is controlled at high speed to increase the flow rate of seawater supplied to the high-concentration oxygen dissolution device. The freshness maintenance system for raw seaweed according to claim 1, wherein, when the second flow path is used, the high-concentration oxygen dissolution device is controlled at a low speed to reduce the flow rate of seawater supplied to the high-concentration oxygen dissolution device.

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