JPH0596283A - Apparatus for removing dissolved oxygen - Google Patents

Abstract

PURPOSE:To efficiently perform the reaction of dissolved oxygen with a small amount of excessive gaseous hydrogen without using a gas-liquid contact device by providing a receiving part of excessively injected gaseous hydrogen to the upper part of the hydrogen mixed water within a catalyst resin tower and providing an automatic opening and closing valve discharging gaseous hydrogen to the atmosphere in connection with a liquid level switch. CONSTITUTION:Hydrogen mixed water obtained by injecting gaseous hydrogen in raw water containing dissolved oxygen is introduced into a catalyst resin tower 1 packed with an ion exchange resin 2 having a catalyst supported thereon and dissolved oxygen is reacted with gaseous hydrogen by the catalyst to be removed as water. A receiving part 11 holding hydrogen mixed water 10 in which the ion exchange resin 2 provided to the lower part of the catalyst resin tower 1 is immersed and receiving gaseous hydrogen excessively injected in the upper part of hydrogen mixed water 10 is provided to the catalyst resin tower 1 and a liquid level switch is attached to the intermediate part of the tower 1. Further, an automatic opening and closing valve 4 discharging the gaseous hydrogen in the receiving part to the atmosphere in connection with the liquid level switch and a pressure switch 12 for holding the pressure in the gaseous hydrogen in the receiving part to a definite value or more are provided to the upper end part of the catalyst resin tower 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing dissolved oxygen in various kinds of water used.

[0002]

2. Description of the Related Art Dissolved oxygen in water has been confirmed to contribute to, for example, corrosion of members in primary and secondary cooling water systems of a nuclear power plant. It must be removed as much as possible.

As an apparatus for this purpose, there is known an apparatus for removing dissolved oxygen by reacting dissolved oxygen with hydrogen using a catalyst resin. In such an apparatus, it is necessary to add hydrogen in some form to raw water containing dissolved oxygen. However, when a water-soluble hydrogen storage compound such as hydrazine or hydrous hydrazine is used as the hydrogen source, it has a drawback of introducing ionic impurities into the raw water. Therefore, if gaseous hydrogen is used as the hydrogen source, there will be no such problems,
In addition, it is cheap, but since gaseous hydrogen has a low solubility in water, it is necessary to supply a large amount of excess gaseous hydrogen, or it is necessary to install a gas-liquid contact device such as a dissolution tower or an ejector in the preceding stage of the device. There was an inconvenience.

Here, the reaction between dissolved oxygen in raw water and gaseous hydrogen will be described below. The solubility of hydrogen in water at atmospheric pressure and a water temperature of 25 ° C is 1.56 mg / liter.
The saturated dissolved oxygen at 25 ° C is 8.11 mg / liter.
Then, the following formula 2H ₂ + O ₂ → 2H ₂ O causes an equivalent reaction between 1 g of hydrogen and 8 g of oxygen.
= 1.02, so 1.56> 1.02 So if hydrogen is dissolved in saturation, hydrogen is theoretically sufficient. However, in order to saturate hydrogen in water, it is necessary to make sufficient gas-liquid contact, and since the reaction time also takes a long time, it was difficult to dissolve enough hydrogen in a short time by the usual means. ..

As a result of various investigations in view of the above, the present invention has developed a dissolved oxygen removing apparatus that efficiently dissolves gaseous hydrogen in water and efficiently reacts with dissolved oxygen, thereby eliminating the conventional gas-liquid contactor. It is a thing.

That is, one of the devices of the present invention is a hydrogen-mixed water obtained by injecting gaseous hydrogen into raw water containing dissolved oxygen in a catalyst resin tower filled with an ion exchange resin carrying a catalyst such as metallic palladium, platinum, or rhodium. In a device for removing the dissolved oxygen as water by reacting the dissolved oxygen with gaseous hydrogen by the action of the catalyst, in the catalyst resin tower, a hydrogen mixture obtained by immersing an ion exchange resin installed in the lower part of the tower. A container for holding the excessively injected gaseous hydrogen, which holds water, is provided above the hydrogen-mixed water, and a liquid level switch is attached to the middle part. Further, the gaseous hydrogen in the container is linked with the liquid level switch. Is provided at the upper end of the above-mentioned catalyst resin tower to release air into the atmosphere.

Further, another one of the apparatus of the present invention is characterized in that the above apparatus is further provided with a pressure switch for maintaining the gas hydrogen pressure in the accommodating portion at a certain value or more at the upper end portion of the catalyst resin tower. It is what

In any of the above devices, it is effective to provide a water conduit above the ion exchange resin in the catalyst resin tower and into the hydrogen mixed water held in the tower. Is.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A device of the present invention will be described with reference to the drawings.

Example 1 A catalyst resin tower as shown in FIG.
The lower part of (1) is filled with a catalyst resin (2) made of an ion-exchange resin supporting metallic palladium or the like, and the upper end of the column (1) has raw water and gas containing dissolved oxygen. Mixed water supply pipe for supplying hydrogen mixed water with hydrogen into the tower (1)
(3) and an automatic opening / closing valve (4) for releasing gaseous hydrogen stored in the upper part of the tower (1) into the atmosphere, and further at an appropriate position shown below in the middle part of the tower (1). Liquid level switches (5) and (5) were installed. A treated water pipe (6) for discharging treated water treated by the catalyst resin (2) out of the apparatus was provided at the lower end of the catalyst resin tower (1). Here, since the internal pressure of the catalyst resin tower (1) is increased by the hydrogen-mixed water and the gaseous hydrogen, the catalyst resin tower (1) has a shape capable of withstanding this pressure. The raw water supply line (7) and the gaseous hydrogen supply line (8) are connected to the mixed water supply pipe (3), and the gaseous hydrogen supply line is further connected.
A check valve (9) is installed at (8) so that raw water is a gaseous hydrogen supply line.
It prevents it from flowing into (8).

First, the hydrogen-mixed water is held in the tower (1) so that the catalyst resin (2) is immersed in a sufficient depth.
(10), and above the water (10) in the tower, a space serving as a storage part (11) for gaseous hydrogen is formed. According to such a device, the hydrogen-mixed water supplied from the mixed-water supply pipe (3) at the upper end of the tower (1) naturally falls in the space of the storage section (11) and the water (1
Since (0) is vigorously stirred with hydrogen bubbles, gaseous hydrogen is easily dissolved in raw water.

When operating the device in the above device,
The amount of hydrogen mixed water supplied from the mixed water supply pipe (3) is preferably 30 to 100 times the catalyst resin amount per hour (this value is referred to as SV value). The operating pressure in the tower (1) is generally higher if the operating pressure is higher according to Henry's law because the solubility of hydrogen increases.

Further, the amount of gaseous hydrogen injected into the raw water is assumed to be in excess of the chemical equivalent, so that undissolved hydrogen gradually accumulates in the accommodating portion (11) as a gas. For example, when the water temperature is 25 ° C, saturated dissolved oxygen is 8.
Since it is 11 mg / liter, if hydrogen equivalent to 150% of the chemical equivalent is injected into oxygen (8.11 / 8) x 1.5 = 1.52 mg / liter 1.52 mg / liter <1.56 mg / liter, the theory is true even if 150% is injected. Although the entire amount of hydrogen dissolves at the atmospheric pressure in the upper part, gaseous hydrogen which cannot be completely dissolved due to the reaction time remains, and this is accumulated in the accommodating portion (11).

When the operation is continued in this manner, the amount of gaseous hydrogen accumulated in the accommodating portion (11) in the catalyst resin tower (1) gradually increases as described above, and due to this pressure, water in the tower (10) Is pressed and the liquid level gradually drops. If the liquid level drops below the specified position, the liquid level switch (5) set at that position will interlock with the automatic open / close valve.
(4) is opened and excess hydrogen is released from the containing section (11) to the atmosphere. In this way, the depth of the tower water (10) (that is, the liquid level position) is always maintained at a predetermined position or higher. This is because if the liquid level drops too much, the distance from the liquid level to the catalyst resin (2) will become too small, and the hydrogen-mixed water falling from above will disturb the catalyst resin (2), and the gaseous hydrogen will not sufficiently dissolve. This is because problems such as the occurrence of hydrogen and the shortage of dissolved hydrogen occur. Therefore, the above liquid level switch (5)
Is the depth from the liquid surface of the water (10) in the tower to the catalyst resin (2),
The effect of hydrogen-mixed water falling from the upper end of the tower (1) on the catalyst resin
(2) It is recommended to install it at a position that is deeper than the depth that does not reach.

(Embodiment 2) In a device as shown in FIG. 2, a pressure switch (12) is provided in the gas hydrogen containing portion (11), and a mixed water supply pipe (3) is extended to introduce a water conduit ( At the same time, the tip was immersed in water (10) in the tower, and a distribution pipe (13) for mixed water was provided at the tip. The distribution pipe (13) may be omitted when the diameter of the catalyst resin tower (1) is small.

The reason why the pressure switch 12 is provided in this way is as follows. That is, when the automatic opening / closing valve (4) is opened and the pressure of the containing portion (11) is lowered as described above, once dissolved hydrogen is separated from the mixed water and gasified and accumulated in the containing portion (11). In this case, the amount of dissolved hydrogen commensurate with the amount of dissolved oxygen to be removed in the mixed water may be insufficient and the dissolved oxygen value in the treated water may increase. Therefore, the automatic switch valve (4) is configured to be closed when the pressure in the housing section (11) drops below a certain value by the pressure switch (12). Further, in the case of FIG. 1 and FIG. 2 described above, if the needle valve (14) is provided before or after the automatic opening / closing valve (4), the opening / closing is adjusted by adjusting the opening according to the throughput of the device. When the valve (4) is opened, it is possible to control the pressure in the housing (11) so that it does not drop too rapidly.

By providing the water conduit (15) as described above, hydrogen in the hydrogen-mixed water always passes through the tower water (10) above the catalyst resin (2), so that the gas-liquid contact efficiency is improved. Is improved and the dissolution of hydrogen is promoted. The opening of the distribution pipe (13) provided in the water conduit (15) is preferably directed upward, and it is more effective if a screen or the like is attached so as to cover the opening so as to promote the fragmentation of bubbles of gaseous hydrogen.

Test Example 1 Using the apparatus shown in FIG. 2, a test for removing this dissolved oxygen from water containing 24 to 25 ° C. containing substantially saturated dissolved oxygen was carried out. The catalyst resin tower used in this test had an inner diameter of 15 cm, and was filled with Amberlite ER-206 (made by Rohm and Haas Co.) as an ion exchange resin carrying metallic palladium to a depth of 65 cm. The surface of the liquid is 60 cm from the top of the ion exchange resin.
And The apparatus was operated under various conditions shown in Table 1 with SV = 100, and as a result, the concentration of dissolved oxygen in the treated water was measured and is also shown in Table 1. The hydrogen injection rate in the table is a percentage of the excess amount when the equivalent hydrogen amount corresponding to the dissolved oxygen amount is 100%.

[0019]

[Table 1]

As can be seen from Table 1, the higher the operating pressure in the tower, the lower the dissolved oxygen concentration in the treated water. This is because the amount of dissolved hydrogen increases as the pressure increases, and it is understood that the dissolved oxygen concentration in the treated water can be suppressed to an extremely low level with a small excess amount of hydrogen.

Test Example 2 Next, Table 2 shows the results of comparing the values of the dissolved oxygen concentration in the treated water when using the same apparatus as in FIG. 2 and when using the same apparatus as in FIG. ..

[0022]

[Table 2]

It can be seen from Table 2 that the presence of the water conduit (apparatus of FIG. 2) has a greater effect of removing dissolved oxygen under the same operating conditions. If there is no water conduit, if the liquid level drops during operation, the gas-liquid contact efficiency begins to drop immediately, and the treated dissolved oxygen concentration also drops immediately, so the operation has a wide range of dissolved oxygen concentrations. It may be lost.

[0024]

As described above, according to the present invention, it becomes possible to sufficiently dissolve hydrogen in a dissolved oxygen removing device using gaseous hydrogen without the use of a gas-liquid contacting device as in the conventional case, and the dissolved oxygen is saturated. Even in raw water in a state, the dissolved oxygen concentration in the treated water can be reduced to 1 μgO / liter or less, which is a significant industrial effect.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 catalyst resin tower 2 catalyst resin 3 mixed water supply pipe 4 automatic open / close valve 5 liquid level switch 6 treated water pipe 7 raw water supply line 8 gaseous hydrogen supply line 9 check valve 10 tower water 11 storage unit 12 pressure switch 13 min pipe 14 Needle valve 15 water conduit

Claims (3)

[Claims] 1. A catalyst resin tower packed with an ion exchange resin carrying a catalyst such as metallic palladium, platinum, rhodium,
In a device for injecting hydrogen-mixed water in which gaseous hydrogen is injected into raw water containing dissolved oxygen and removing the dissolved oxygen as water by reacting with the gaseous hydrogen by the action of the catalyst, in the catalyst resin tower, Holds the hydrogen-mixed water in which the ion-exchange resin set in the lower part of the tower is immersed, and the accommodating part for the excessively injected gaseous hydrogen is provided above the hydrogen-mixed water, and the liquid level switch is attached to the middle part. Further, the dissolved oxygen removing device is characterized in that an automatic on-off valve for releasing the gaseous hydrogen in the accommodating portion to the atmosphere in conjunction with the liquid level switch is provided at the upper end of the catalyst resin tower. 2. A catalyst resin tower packed with an ion exchange resin carrying a catalyst such as metallic palladium, platinum, rhodium,
In a device for injecting hydrogen-mixed water in which gaseous hydrogen is injected into raw water containing dissolved oxygen and removing the dissolved oxygen as water by reacting with the gaseous hydrogen by the action of the catalyst, in the catalyst resin tower, Holds the hydrogen-mixed water in which the ion-exchange resin set in the lower part of the tower is immersed, and the accommodating part for the excessively injected gaseous hydrogen is provided above the hydrogen-mixed water, and the liquid level switch is attached to the middle part. Further, an automatic opening / closing valve for releasing the gaseous hydrogen in the accommodating portion to the atmosphere in conjunction with the liquid level switch and a pressure switch for keeping the pressure of the gaseous hydrogen in the accommodating portion above a certain value are provided at the upper end of the catalyst resin tower. Dissolved oxygen removing device, characterized in that it is provided in the section. 3. The dissolved solution according to claim 1 or 2, wherein a water pipe is provided above the ion-exchange resin in the catalyst resin tower and into the hydrogen-mixed water held in the tower. Oxygen removal device.