JPH0989873A - Dissolved oxygen-measuring apparatus and method for using the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dissolved oxygen-measuring apparatus which is an a simple structure without adverse influences of clogging of dust, corrosion, etc., can apply a necessary flow velocity with a small consuming amount of power to water in touch with an electrode, and is suitable to measure continuously for a long time particularly in a fish preserve of a wide farm. SOLUTION: An air lift tube 3 is set at a water exit 1b of a flow cell 1 in which an electrode 2 for measuring dissolved oxygen is disposed. The flow cell 1 is placed in water. At this time, an air introduction opening 3a of the air lift tube 3 is kept under the surface of water. A flow of water is generated in the flow cell 1 when the air is injected through an air pump 4, whereby dissolved oxygen in water is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the concentration of oxygen dissolved in water, and more particularly, to a device for measuring dissolved oxygen suitable for use in raw fish for aquaculture of fish and shellfish, and a method of using the device.

[0002]

2. Description of the Related Art In recent years, seafood has been increasingly cultivated mainly in high-grade fish such as gussets and scallops, and a large number of raw fishes for such aquaculture have been installed in the waters near Japan and lakes. However, the red tide is severely damaged in the waters near Japan, and the damage caused by the red tide and oxygen deficiency is also occurring in lakes, and the seafood cultivated in raw fish is also suffering a large amount of damage.

As one of the methods for preventing the damage such as the red tide in advance, the amount of dissolved oxygen in seawater or lake water is continuously measured, and when the amount of dissolved oxygen reaches a dangerous level, It is considered to prevent damage by moving the seafood and raw fish itself to another place. As an apparatus for measuring dissolved oxygen for that purpose, an apparatus by an electrode method capable of continuous measurement has been developed.

However, in the measurement of dissolved oxygen by the electrode method, a certain flow velocity is required for the water contacting the electrode. Therefore, in the case of measuring dissolved oxygen in a raw porcelain installed in the sea or lake, an underwater stirrer is used. It is necessary to forcibly apply the flow velocity with a water pump or a water pump. In particular, in order to carry out the measurement in a large farm where the raw fish is installed, the measurement electrode is mounted on a buoy or the like, and a battery is inevitably used as a power source.

[0005]

As described above, in order to protect raw fish for aquaculture in the near sea or lake from damage such as red tide,
Measurement of dissolved oxygen Dissolved oxygen in seawater or lake water at any place in the raw fish is continuously measured by an electrode method using an electrode.

However, in the measurement of dissolved oxygen by the electrode method, it is necessary to forcibly give an appropriate flow velocity to the water contacting the electrode. Therefore, in a measurement in a large farm, the flow velocity is forcibly provided, so that the battery is used as an underwater stirrer. The water pump is driven, but due to its structure or power consumption, continuous measurement for a long time was difficult.

That is, in the underwater stirrer, a rotor arranged in the vicinity of the electrodes is rotated by a stirrer motor to obtain a required flow velocity, and although the power consumption is low, the structure of the liquid contact part of the underwater stirrer is complicated. Therefore, dust clogging and biological adhesion tend to occur, and when used in the sea, corrosion resistance becomes a problem, making continuous operation difficult for a long period of time.

In the water pump system, a pump is arranged in the water flow path in contact with the electrodes to make the water flow, and a magnet pump, a metering pump, a bellows pump,
Gear pumps are usually used. However, these pumps themselves are vulnerable to clogging with dust and adhesion of organisms, and when used in the sea, corrosion resistance becomes a problem, and power consumption for driving the pumps is large, so they are not suitable for long-term continuous use. There was a flaw.

In view of the above conventional circumstances, the present invention has a simple structure that does not have a bad influence due to clogging of dust, adhesion of organisms, corrosion, etc., and can provide water having a required flow velocity to the water contacting the electrode with low power consumption. It is an object of the present invention to provide a dissolved oxygen measuring device which is suitable for continuous measurement at any place in the raw fish of a large aquaculture farm installed in the near sea or a lake.

[0010]

In order to achieve the above object, a dissolved oxygen measuring device provided by the present invention is a flow cell having a water inlet and a water outlet provided above the water inlet, and water of the flow cell. An electrode for measuring dissolved oxygen arranged between the inlet and the water outlet, an air lift pipe communicating with the water outlet of the flow cell and extending upward, and having an air inlet near the water outlet, and air introduction of the air lift pipe. An air pump for injecting air into the mouth is provided.

The method of using this dissolved oxygen measuring device is as follows: the flow inlet is placed below the water so that the air inlet of the air lift pipe is submerged below the water surface, and the air is introduced into the air inlet of the air lift pipe. Dissolved oxygen in water is measured while forming a flow of water from the water inlet to the water outlet in the flow cell by injecting.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the dissolved oxygen measuring apparatus of the present invention,
An air lift pipe is used as a means of giving a flow velocity to the water in the flow cell. That is, as shown in FIG. 1, the device of the present invention comprises a flow cell 1 having a water inlet 1a and a water outlet 1b provided above the water inlet 1a, and between the water inlet 1a and the water outlet 1b of the flow cell 1. An air lift pipe 3 that communicates with the placed dissolved oxygen measuring electrode 2 and the water outlet 1b of the flow cell 1 and extends upward, and has an air inlet 3a near the water outlet 1b, and an air inlet of the air lift pipe 3. 3a, and an air pump 4 for injecting air.

In the apparatus for generating a water flow in the flow cell using the air pump of the present invention, as shown in FIG. 2, by injecting the air A into the air introduction port 3a of the air lift pipe 3, the air A is generated. Bubbles B rise in the air lift pipe 3 and the water C is sequentially pushed up by the bubbles B and discharged from the upper end opening 3b, so that the same volume of water as the discharged water is supplied from the water inlet of the flow cell. Inflow,
By repeating this, a flow of water is formed in the flow cell.

As described above, in the dissolved oxygen measuring apparatus of the present invention, the structure for generating the water flow is simple and the air pump can be arranged at a place where it does not come into direct contact with water. Therefore, the dissolved oxygen can be measured by continuously generating a water flow in the flow cell over a long period of time. Further, if the depth of the water under the air inlet is determined and fixed, the measurement depth can be freely selected without changing the capacity of the air pump, for example, by changing the depth of the water inlet of the flow cell. Furthermore, since an air pump that consumes less power is used, continuous measurement can be performed for a long period of time using a battery power source, which is suitable for use in live fish of a large aquaculture farm.

The dissolved oxygen measuring electrode 2 may be an ordinary electrode, for example, a cathode provided in close contact with the diaphragm and a separately provided anode in a cylinder partitioned from the outside by a breathable diaphragm. However, it has a configuration in which it is immersed in an electrolytic solution and arranged. When oxygen that permeates the diaphragm reaches the cathode, an electric current flows between the cathode and the anode due to an electrochemical reaction when it is reduced there, and the electric current is proportional to the amount of oxygen. Therefore, the flowing current is guided to the converter 5 in FIG. 1 and is converted into the measured value of dissolved oxygen.

When the dissolved oxygen in water is measured by using the device of the present invention, the air introduction port 3a of the air lift pipe 3 is used.
The flow cell 1 is placed in water with the water inlet 1a facing downward so that the water cell 1 sinks below the water surface. In this state, by injecting air from the air pump 4 into the air introducing port 3a of the air lift pipe 3, the water in the air lift pipe 3 is pushed up by the air and discharged from the upper end opening 3b. Therefore, the same volume of water as the discharged water flows in from the water inlet 1a of the flow cell 1, and by repeating this, a flow of water is formed in the flow cell 1 from the water inlet 1a to the water outlet 1b. Therefore, it becomes possible to measure dissolved oxygen.

In order to make a correct measurement of the dissolved oxygen by the measuring electrode, the flow velocity of water in the flow cell, more precisely, the flow velocity of water at the water passage at the place where the measuring electrode is installed, is not less than 10 cm / sec. Is preferably given. The flow velocity of water in this flow cell changes depending on the inner diameter and length of the air lift tube, the flow rate of air introduced into the air lift tube, the cross-sectional area of the water passage port where the measurement electrode is installed in the flow cell, etc. The required flow rate can be obtained by selecting

For example, the inner diameter of the upper opening is 6.7 mm and 1
FIG. 3 shows the flow rate of water flowing through the air lift pipe when the 3 mm air lift pipe has its upper end opening located 10 mm below the water surface and the flow rate of the air injected from the air introduction port is changed. As can be seen from this graph, the water flow rate increases as the upper end opening of the air lift pipe increases with the same air flow rate. Therefore, when the same water flow rate is obtained, the air flow rate can be reduced by increasing the diameter of the upper end opening,
If the diameter of the upper end opening is large, the efficiency of pushing up water by air bubbles decreases, and if there is a wave at the installation location, water may flow back through the air lift pipe due to the effect. Also, even if the air flow rate is made too large, there is a limit to the water flow rate as can be seen from FIG.

As described above, in the device of the present invention, since the flow of water is created in the flow cell by injecting air into the air lift pipe, most of the air lift pipe including the air introduction port must be below the water surface. Is. However, when the installation depth of the flow cell becomes deep, it is necessary to inject air at a pressure higher than the water pressure at that depth. Therefore, the required air pressure of the air pump is determined by the installation depth of the flow cell, more precisely, the depth of the air inlet, and the higher the capacity of the air pump, the deeper the depth of the air inlet can be. However, generally, in consideration of the power consumption of the air pump, it is preferable that the air introduction port of the air lift pipe is within about 10 m from the water surface.

The flow cell is installed at the above depth, but as shown in FIG. 1, the water inlet 1a is extended downward to form a long water inlet pipe 6, or from the water outlet 1b to the air inlet 3a. Maximum length of about 30m
It is possible to measure water up to any depth. On the other hand, the position of the upper end opening 3b of the air lift pipe 3 is not particularly specified, but is preferably in the range of about 15 cm above the water surface to about 10 m below the water surface. If the air inlet 3a of the air lift pipe 3 and the air pump 4 are separated,
Because the tube resistance increases and the power consumption increases as much,
The distance between the two is preferably as close as possible.

As described above, in the dissolved oxygen measuring apparatus of the present invention using the air lift pipe, the contact portion between the measuring apparatus and water is simplified, and therefore, compared with the conventional method using an underwater stirrer or a water pump. The problems of clogging and corrosion due to dirt, foreign substances and biological adhesion are reduced. However, since foreign matter such as dust in water may be clogged in a narrow portion such as the flow cell, it is preferable to provide a filter 7 at the water inlet 1a of the flow cell 1 as shown in FIG.

Size of the mesh of the filter 7 (mesh diameter)
Is preferably equal to or less than the distance between the narrowest part in the flow cell, usually the measuring electrode and the inner wall of the flow cell, in order to prevent clogging. However, if the mesh size of the filter is too small, it will easily become clogged. On the contrary, if it is too large, there will be no effect of removing foreign matter.
About 5 mm is suitable.

Next, as a means for giving a flow velocity to water, Table 1 shows a comparison of power consumption of an underwater stirrer, various water pumps, and an air pump connected to the air lift pipe of the present invention. It can be seen from Table 1 that the present invention using the air pump consumes less power than the conventional devices using various water pumps. Further, in the device of the present invention, since the structure of the contact portion between the measuring device and water is not complicated unlike an underwater stirrer or a water pump, clogging due to dust and biological adherence is unlikely to occur, and adverse effects due to corrosion are eliminated.

[0024]

TABLE 1 flow given hand stage water flow with speed (l / min) Power (W) in water stirrer - 0.5 magnet pump 8 3 metering pump 0.85 250 bellows pump 0.8 26 gear pump 1.9 20 pump 1.5 * 2.5 Note: the air pump In this case, the column of water flow rate is the air discharge amount.

[0025]

EXAMPLE One specific example of the dissolved oxygen measuring apparatus of the present invention is shown in FIG. This device includes a water inlet 1a and the water inlet 1a.
A synthetic resin flow cell 1 provided with a water outlet 1b provided above, and a dissolved oxygen measuring electrode 2 arranged between the water inlet 1a and the water outlet 1b of the flow cell 1 (OE-manufactured by Toa Denpa Kogyo KK). 383). The distance between the measurement electrode 2 and the inner wall of the flow cell (in this example, the inner wall provided with the water inlet 1a) was set to 5 mm, and the inner diameter of the water inlet 1a was 7 mm.

The water outlet 1b of the flow cell 1 is connected to an air lift pipe 3 made of synthetic resin having an inner diameter and an inner diameter of the upper end opening 3b of 6.7 mm, and the air lift pipe 3 communicates with the flow cell 1 and extends upward. And the length is about 10 cm
It has become. Also, at the lower end of the air lift pipe 3, the water outlet 1
An air inlet 3a is provided near b.

On the other hand, the water inlet 1a of the flow cell 1 is provided with a water inlet pipe 6 extending downward and having an inner diameter of about 30 to 40 mm, the length thereof is about 10 cm, and the lower end opening thereof has a mesh diameter of 4 mm. A ~ 7 mm filter 7 is attached.
The upper end of the flow cell 1 located on the opposite side of the filter 7 is an inclined portion 10 inclined with respect to the vertical direction. By providing the inclined portion 10, the flow of water becomes smooth and there is no accumulating portion. Even if air enters the flow cell 1 for some reason, it does not accumulate and is discharged from the air lift pipe 3.

This dissolved oxygen measuring device is placed in water with the water inlet 1a facing down so that the upper end opening 3b of the air lift pipe 3 is sunk to about 10 mm below the water surface, and an air pump is installed at the air inlet 3a of the air lift pipe 3. 4 to about 60ml of air
It was injected at a flow rate of min. As a result, the water rises in the air lift pipe 3 together with the injected air bubbles, and the flow velocity in the flow cell 1 increases from the water inlet 1a to the water outlet 1b by 10
A flow of water of cm / sec or more was formed, and the dissolved oxygen in the water could be accurately measured continuously by the measuring electrode 2 without clogging of dust.

The dissolved oxygen measuring apparatus of the present invention can also incorporate a water quality measuring sensor for other measurement items at the same time. For example, as shown in FIG. 4, if an electric conductivity sensor 8 and a temperature sensor 9 are attached to the flow cell 1 together with the dissolved oxygen measuring electrode 2, the electric conductivity (salt concentration) of water and The temperature can be measured.

[0030]

According to the present invention, it has a simple structure with no clogging of dust and the like, there is no decrease in pumping capacity due to biofouling and corrosion, and the water in the flow cell in contact with the electrode requires less power consumption. Since the flow rate can be given, the dissolved oxygen in water can be continuously and accurately measured.

Further, since this dissolved oxygen measuring device can measure in deep water and uses an air pump with low power consumption, a DC current from a battery can be used as a power source, and continuous measurement for a long time becomes possible. Therefore, it is particularly suitable for continuous measurement at any place in the raw fish of a large aquaculture farm installed in the near sea or a lake.

[Brief description of drawings]

FIG. 1 is a schematic view showing a specific example of a dissolved oxygen measuring device of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining the action of the air lift pipe of the device of the present invention.

FIG. 3 is a graph showing a relationship between an air flow rate given to an air lift pipe and a water flow rate in a flow cell.

FIG. 4 is a schematic view showing another specific example of the dissolved oxygen measuring apparatus of the present invention.

[Explanation of symbols]

 1 Flow Cell 1a Water Inlet 1b Water Outlet 2 Measuring Electrode 3 Air Lift Pipe 3a Air Inlet 3b Top Opening 4 Air Pump 5 Converter 6 Water Inlet Pipe 7 Filter 8 Electrical Conductivity Sensor 9 Temperature Sensor 10 Slope

Front page continuation (72) Inventor Yasui Koiso 613 Kitairizo, Sayama-shi, Saitama Prefecture Toa Denpa Kogyo Co., Ltd. Sayama Plant (72) Inventor ▲ Kyoko Takami 5-7 Shiba, Minato-ku, Tokyo Japan Electric stock company

Claims (7)

[Claims] 1. A flow cell having a water inlet and a water outlet provided above the water inlet, a dissolved oxygen measuring electrode arranged between the water inlet and the water outlet of the flow cell, and a water outlet of the flow cell. An apparatus for measuring dissolved oxygen, comprising: an air lift pipe that communicates and extends upward, and has an air introduction port near the water outlet; and an air pump that introduces air into the air introduction port of the air lift pipe. 2. The dissolved oxygen measuring device according to claim 1, wherein a water inlet of the flow cell is equipped with a filter. 3. The mesh size of the filter is 4-5.
mm, The dissolved oxygen measuring device of Claim 2 characterized by the above-mentioned. 4. At least one water quality measuring sensor is provided between the water inlet and the water outlet of the flow cell in addition to the dissolved oxygen measuring electrode. The dissolved oxygen measuring device according to claim 1. 5. The dissolved oxygen measuring apparatus according to claim 1, wherein the flow cell is placed in water with the water inlet down so that the air introduction port of the air lift pipe is submerged below the water surface, and the air introduction of the air lift pipe is performed. A method for using a dissolved oxygen measuring device, characterized by measuring dissolved oxygen in water while forming a flow of water from a water inlet toward a water outlet in the flow cell by injecting air into the mouth. 6. The method for using the dissolved oxygen measuring device according to claim 5, wherein the air inlet of the air lift pipe is located within 10 m from the water surface. 7. The method for using the dissolved oxygen measuring device according to claim 5, wherein the upper end opening of the air lift pipe is located within 15 cm above the water surface and within 10 m below the water surface.