JP3224037B2 - Deoxygenation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a device for removing water dissolved oxygen, more specifically, to a device for removing oxygen using hydrogen gas (H ₂₎ and a catalyst resin.

[0002] Today, large amounts of water are used as boiler water and cooling water. However, if oxygen is dissolved in these waters, there is a problem of corrosion caused by dissolved oxygen in a boiler water system or a cooling water system through which the water passes.
Therefore, dissolved oxygen in water must be removed by a chemical method or a physical method.

[0003] Ultrapure water for the semiconductor industry also needs to have an extremely low dissolved oxygen concentration. That is, in the ultrapure water production system for the semiconductor industry,
It is necessary to reduce the dissolved oxygen to 100 ppb or less, preferably 20 ppb or less.

[0004]

2. Description of the Related Art Conventionally, methods for removing dissolved oxygen in water include (1) a method of heating pure water to degas, and (2) a method of removing dissolved gas by reducing the pressure to about the vapor pressure of water. ,
(3) a method of diffusing dissolved oxygen from water into a gaseous phase by using only a gas at the gas-liquid contact surface as nitrogen gas, (4) a method using a difference in gas permeability of a hydrophobic polymer membrane, (5) ) A method of removing dissolved oxygen with a catalyst resin having a certain metal supported on the surface of an ion exchange resin has been performed.

[0005]

Among these, in the methods (1) to (4), all the gases that are dissolved in the water in the object (in the method (3) using nitrogen, Therefore, there is a disadvantage that gases other than oxygen are also removed at the same time. The method (3) using nitrogen has a disadvantage that water after treatment is saturated with nitrogen.

As the method (5) using a catalyst resin, for example, as described in JP-B-59-32195 and JP-A-2-265604, noble metals such as palladium are supported. There is a method of removing dissolved oxygen by adding hydrogen using a catalyst. That is, this is a method in which dissolved oxygen and hydrogen are reacted in the presence of a catalyst to change the water to water.

In this method, the dissolved oxygen in the treated water is reduced to 1
In order to make it 0 ppb or less, the amount of hydrogen to be implanted needs to be 1.1 to 1.3 times the theoretical value. In addition, even if the injection amount of hydrogen gas is controlled in accordance with the concentration of dissolved oxygen, the amount of hydrogen gas does not exceed 0.
1 to 0.3 ppm of hydrogen gas is dissolved in the treated water. In addition, hydrogen gas during the process is dangerous because it accumulates in the upper portion of the processing tank or the pipe. Further, as the cleaning water for semiconductor wafers, there is a problem that such treated water causes the generation of bubbles. In addition, there is a problem that running cost is increased due to excessive injection of hydrogen gas, and there is a possibility that embrittlement due to hydrogen of a metal material occurs in a boiler or a heat exchanger.

The present invention has been made in view of the above-mentioned problems of the prior art and solves the problems caused by dissolved hydrogen by reducing the consumption of hydrogen gas and reducing the amount of dissolved hydrogen gas after treatment to 0.01 ppm or less. It is an object of the present invention to provide a deoxygenation device which can be used.

[0009]

The present invention provides the following deoxygenation apparatus.

(1) In a deoxygenation apparatus for removing oxygen from water by utilizing a reaction for producing water from hydrogen and oxygen in the presence of a palladium catalyst, a hydrogen line for injecting hydrogen gas into water to be treated, A deoxygenation tower downstream of the hydrogen line and filled with a palladium catalyst, a vacuum deaerator or a membrane deaerator provided at an outlet of the deoxygenation tower, and a vacuum deaerator or a membrane deaerator. Separated from the treated water,
A deoxygenation apparatus comprising a gas line for injecting a gas mainly containing hydrogen into the upstream of the deoxygenation tower.

(2) In the deoxygenation apparatus of the above (1),
In order to supply a vacuum to the vacuum deaerator or the membrane deaerator, an ejector operated by a flow of the water to be treated and connected to the gas line is provided upstream of the deoxygenation tower. Deoxygenation device.

(3) In the deoxidizer of the above (2),
A deoxygenation apparatus, comprising: installing a hydrogen gas separation membrane device in the gas line between the vacuum deaerator or the membrane deaerator and the ejector, and returning only the hydrogen gas from the ejector to the water to be treated.

In the apparatus of the present invention, dissolved oxygen is removed by reacting hydrogen added to the water to be treated with dissolved oxygen using palladium as a catalyst. That is, an excess amount of hydrogen gas is added to water containing dissolved oxygen, and in the presence of a palladium catalyst,
Water is generated by a chemical reaction between oxygen and hydrogen to remove dissolved oxygen.

As the palladium catalyst, a catalyst in which a palladium compound such as palladium metal, palladium oxide or palladium hydroxide is supported on a carrier such as ion exchange resin or alumina, activated carbon or zeolite can be used.
In this case, the loading amount is usually 0.1 to 10 as an outer part with respect to the single substance.
% By weight. As the carrier, in particular, by using an anion exchange resin, with a small amount of palladium carried,
An excellent effect can be exhibited, which is very suitable.

In order to carry palladium on the anion exchange resin, the column is filled with the anion exchange resin, and then an aqueous solution of palladium chloride is passed through. If it is supported as metal palladium, it may be reduced by further adding formalin or the like.

The shape of the palladium catalyst may be powdery, granular,
Any shape such as a pellet shape can be used. When a powdery material is used, a reaction tank is provided in a deoxygenation tower, and an appropriate amount is added to the reaction tank. Granules or pellets are advantageous when packed in a column or the like and the water to be treated is passed continuously. Of course, even in powder form,
It can be packed in a column and subjected to water treatment in a fluidized bed.

The water to be treated by the apparatus of the present invention includes not only pure water but also, for example, boiler feed water and cooling water.

After the treatment in this deoxygenation tower, other gas components such as excess hydrogen gas are further separated by a vacuum deaerator or a membrane deaerator.

As the vacuum deaerator, a device in which a deaerator is filled with a filler such as Raschig rings can be used. A vacuum is supplied from the upper part of the degassing tower, and water to be treated is jetted from a nozzle on the packing to remove hydrogen by vacuum degassing.

Further, as the above-mentioned membrane deaerator, for example, an apparatus using a membrane such as silicon resin or polyfluoroethylene can be used.

The vacuum required by the vacuum deaerator or the membrane deaerator can be supplied using a vacuum pump. Instead, an ejector may be provided at the inlet of the deoxygenation tower. it can. That is, utilizing the flow of the water to be treated, the ejector is used as a vacuum source for a vacuum line connecting the ejector to the dehydrogenation tower. By using an ejector, a separate power source for vacuum supply is not required, and the equipment can be simplified.

As described above, gas components other than oxygen are separated in the vacuum deaerator or the membrane deaerator, and the separated gas containing a large amount of hydrogen gas is returned to the deoxygenation tower via an ejector or a vacuum pump. . As a result, the amount of hydrogen gas used can be reduced, and the danger that hydrogen gas contained in the treated water accumulates in downstream piping and the like can be avoided.

Further, only the hydrogen gas can be separated from the gas thus separated by using a hydrogen separation membrane or the like and returned to the deoxygenation tower. According to this, the water quality after the treatment can be further improved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the drawings.

FIG. 1 shows the configuration of a first embodiment of the apparatus of the present invention. Water to be treated is sent from a tank 1 for storing water to be treated by the apparatus of the present invention to a deoxygenation tower 4 through a treated water line 3 by a pump 2. Hydrogen gas is injected from the hydrogen gas line 5 into the line. An ejector 6 is provided in the treated water line 3 immediately before the inlet of the deoxygenation tower 4. The deoxygenation tower 4 is provided with a resin supporting a palladium catalyst, for example, Lewatit OC1 manufactured by Bayer AG.
It is filled with a palladium catalyst such as 063 or OC1045 supported on an anion exchange resin, and an excess amount of hydrogen gas and oxygen in water react with this catalyst to become water.

The water from which oxygen has been chemically removed in the deoxygenation tower 4 is sent to a dehydrogenation tower 7 filled with Raschig rings and a filler. A vacuum line 8 connected to the ejector 6 is connected to the dehydrogenation tower 7. That is, the ejector 6 operates using the flow of water flowing into the deoxygenation tower 4 to evacuate the dehydrogenation tower 7. The use of the ejector 6 eliminates the need for a separate power source such as a vacuum pump for performing vacuum degassing. In the dehydrogenation tower 7, gases other than oxygen, such as hydrogen, are physically deaerated in vacuum. The water that has been processed in the dehydrogenation tower 7 is discharged by the pump 9. By this vacuum degassing,
The concentration of dissolved hydrogen gas in the treated water can be reduced, and the danger of hydrogen gas accumulating in piping and the like, and the generation of bubbles when used as cleaning water for semiconductor wafers can be prevented.

FIG. 2 shows the configuration of a second embodiment of the apparatus of the present invention. For the same parts, the same reference numerals as those in FIG. 1 are used, and duplicate descriptions are omitted. As in the first embodiment, the water to be treated is injected with hydrogen gas,
It flows into the deoxygenation tower 4 through the ejector 6. Deoxygenation tower 4 filled with the same palladium catalyst as in the first embodiment
In, a reaction between oxygen and hydrogen occurs to remove oxygen. Then, in the membrane deaerator 10 having a deaeration film such as a silicon resin or a polyfluoroethylene, gases other than oxygen, such as hydrogen and nitrogen, are further removed from the water from which oxygen has been removed. The membrane deaerator 10 includes an ejector 6
Is supplied by a vacuum line 8 leading to a vacuum.
A hydrogen gas separator 11 is provided in the middle of the vacuum line 8, and further separates only hydrogen from various gases separated in the membrane deaerator 10. Here, the separated hydrogen gas is added to the water to be treated in the ejector 6, but nitrogen and other gases other than hydrogen are discharged from the hydrogen gas separation device 11. By collecting and reusing hydrogen gas in this way, the amount of hydrogen gas used can be reduced, and by separating and adding only hydrogen gas to the treated water, the water quality after treatment can be further improved. it can.

Experimental Example A catalyst resin Lewatit OC1063 manufactured by Bayer AG
Was packed in a 20 liter SUS column (200 mm in diameter x 1000 mm in length). An ejector was provided at the inlet of the deoxygenation tower composed of this column, and a hollow piece type membrane deaerator with a membrane area of 0.5 m ² was provided at the subsequent stage of the deoxygenation tower. While injecting hydrogen gas into this deoxygenation tower at a flow rate of 1.3 g / hr,
Pure water containing 8 ppm of dissolved oxygen was passed at a flow rate of 1000 liter / hr with an operating pressure of 2.5 kg / cm ² . The pressure reduced by the ejector was 650 mmHg.

Comparative Example An experiment was conducted by removing the membrane deaerator and the ejector from the apparatus of the above experimental example, and maintaining the same other physical conditions.

Table 1 shows the results of the above experimental examples and comparative examples.

[Table 1]

[0031]

According to the deoxidizer of the present invention, the consumption of hydrogen gas can be reduced, and the amount of dissolved hydrogen gas after treatment can be reduced to 0.01 ppm or less to solve the problem caused by dissolved hydrogen. High-quality water from which oxygen has been removed by the deoxidizer of the present invention can be used as boiler water or cooling water, and does not cause corrosion problems. Further, the apparatus of the present invention is also suitable as an apparatus for producing ultrapure water used in the field of the semiconductor industry, and can prevent generation of bubbles which are a problem in the production of wafers.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the apparatus of the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the apparatus of the present invention.

[Explanation of symbols]

 Reference Signs List 1 treated water storage tank 2 pump 3 treated water line 4 deoxygenation tower 5 hydrogen gas line 6 ejector 7 dehydrogenation tower (vacuum deaerator) 8 vacuum line 9 pump 10 membrane deaerator 11 hydrogen gas separator

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B01D 19/00 C02F 1/20 C02F 1/58

Claims (3)

(57) [Claims] 1. A deoxygenation apparatus for removing oxygen from water using a reaction of generating water from hydrogen and oxygen in the presence of a palladium catalyst, comprising: a hydrogen line for injecting hydrogen gas into water to be treated ; A deoxygenation tower to which the injected water to be treated is supplied and filled with a palladium catalyst; a vacuum deaerator or a membrane deaerator provided downstream of the deoxygenation tower; The gas mainly containing hydrogen separated from the water to be treated in the gasifier is supplied to the deoxygenation tower .
And a gas line for injecting water to be treated . 2. A gas mainly containing hydrogen is supplied to the water to be treated in order to supply a vacuum to the vacuum deaerator or the membrane deaerator.
An ejector operated by the water to be treated is installed at the injection point.
Deoxygenation apparatus according to claim 1, characterized in that the location. 3. established a hydrogen gas separation membrane system to the gas line, de-described only hydrogen gas separated by the hydrogen gas separation membrane system in claim 2, characterized in that injecting the water to be treated Oxygen equipment.