JP2507597Y2 - Dissolved oxygen removal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an apparatus used for producing various kinds of water such as water for cleaning semiconductor wafers, medical water, and water for advanced analytical instruments in the electronic industry, for example, a membrane. The present invention relates to a dissolved oxygen removing device that efficiently obtains deoxygenated water having an extremely low dissolved oxygen concentration by combining a degassing device and a deoxidizing device using a deoxidizing resin.

<Prior art> Water for cleaning semiconductor wafers in the electronics industry, pharmaceutical water, water for advanced analytical instruments, etc., is water that has removed dissolved oxygen as much as possible that may cause generation of oxide films and microorganisms. Has been done. As a method of removing the dissolved oxygen, for example, there is a method of removing it using a deoxidizing resin in which a reducing copper is held in a weakly basic anion exchange resin, or a property of passing a gas such as oxygen but not allowing a liquid to pass therethrough. A method using a membrane deaerator equipped with a deaerator is used. Further, in recent years, an apparatus in which the membrane degassing apparatus and an apparatus for removing dissolved oxygen by purging nitrogen into water to reduce the oxygen partial pressure in water have been studied and partially put into practical use.

The flow of the apparatus will be described with reference to FIG. 2. Raw water such as pure water is supplied to a membrane degassing apparatus 52 equipped with a degassing membrane 53 via a water supply pipe 51, and the raw water is separated by the degassing membrane 53. Flow through one of the chambers, while decompressing the other chamber partitioned by the degassing membrane 53 using a vacuum device 54, so that only gases such as oxygen and free carbon dioxide pass through the degassing membrane 53 outside the system. The first-stage treated water is supplied to the nitrogen purge device 55 in order to further reduce the dissolved oxygen remaining in the treated water, which is the deaerated water. The purging device 55
Is usually composed of a plurality of aeration tanks 56 (however, only one tank is shown in the figure), a nitrogen supply device 57, and a nitrogen supply pipe 58 connecting both of them, and the treated water in the first stage is stored in the aeration tank 56. The nitrogen gas is supplied from the upper portion of the aeration tank 56 through the nitrogen supply pipe 58 from the lower portion of the aeration tank 56 for aeration, and the treated water of the first stage is brought into contact with the nitrogen gas in the aeration tank 56 so that the first stage A second stage aeration process is performed to lower the oxygen partial pressure in the treated water and discharge dissolved oxygen into the atmosphere.

However, the above-mentioned method also has various problems. That is, in the case of treating with a deoxidizing resin, if you try to directly treat ordinary water with a dissolved oxygen concentration of 8 to 9 mg / l, the life of the deoxidizing resin becomes extremely short and the replacement of the deoxidizing resin Or you have to play it often,
Alternatively, it is necessary to increase the amount of resin in order to reduce the frequency of these, and as a result, there is a drawback that the deoxidizer must be enlarged. Further, when only the membrane degassing device is used, for example, when trying to obtain treated water having a dissolved oxygen concentration of about 10 ppb, which is required for megabit-class semiconductor wafer cleaning water, a high vacuum and a high displacement vacuum are obtained. Equipment is required, which results in bulky vacuum equipment and high cost.

Further, in a device in which a membrane degassing device and a nitrogen purging device are combined, nitrogen must be supplied from the outside in the second stage aeration process, and therefore, for example, a nitrogen supply device such as a nitrogen cylinder must be installed. I won't. But,
Removal of dissolved oxygen by nitrogen purging is relatively inefficient and requires a large amount of nitrogen.Therefore, it is necessary to change the nitrogen cylinder frequently, which requires maintenance, and the running cost increases significantly. is there. Further, since it is difficult to sufficiently remove dissolved oxygen in one stage of the aeration tank, it is usually necessary to install a plurality of stages of deaeration tanks, which has a drawback that the installation space must be increased.

<Problems to be solved by the invention> The present invention has been made in view of the above-mentioned current situation.
The purpose is to provide a dissolved oxygen removal device that does not require external supply of purging gas such as nitrogen, can be compactly housed in the entire device, and can highly remove dissolved oxygen. There is a place to do it.

<Means for Solving Problems> The present invention made to achieve the above-mentioned object is a membrane degasser equipped with a degassing membrane for removing dissolved gas such as oxygen dissolved in raw water. A device and a dissolved oxygen removing device comprising a deoxygenating device filled with a deoxidizing resin for further removing a trace amount of dissolved oxygen remaining in degassed water that is treated water of the membrane deaerating device, wherein: It has a pump for supplying raw water to one chamber partitioned by the degassing membrane of the membrane degassing device via a water supply pipe, and an ejector for depressurizing the other chamber partitioned by the degassing membrane. The drive water side of the ejector is connected to a drive water pipe branched from the water supply pipe.

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of a flow showing an example of an embodiment of the present invention, in which 1 is a membrane degassing apparatus equipped with a degassing membrane 2 having a property of passing a gas such as oxygen but not a liquid, Three
Is a deoxidizing device arranged in the latter stage of the membrane degassing device 1, and the deoxidizing device 3 is filled with, for example, a deoxidizing resin 4 in which reducing copper is held in a weakly basic anion exchange resin. ing. Further, 5 is a pump for supplying raw water to one chamber partitioned by the degassing membrane 2 of the membrane degassing device 1, and 6 is the other pumped by the degassing membrane 2 of the membrane degassing device 1. An ejector for decompressing the chamber, the suction side of the ejector 6 is connected to the other chamber by a suction pipe 7, and the driving water side of the ejector 6 is a driving water pipe 8 for connecting the pump 5 and the membrane. Water supply pipe 9 for connecting with the deaerator 1
Is branched and connected in the middle of. In addition, 10 is a raw water tank for storing raw water, 11 is a degassing water pipe for taking out degassed water which is the treated water of the membrane degassing device 1 and guiding it to the deoxidizing device 3 in the subsequent stage, and 12 is a deoxidizing device. 3 is a treated water pipe for taking out treated water, and 13 and 14 are valves.

<Operation> The present invention is configured as described above. When the treated water that is deoxidized water is obtained, the pump 5 is driven and a part of the raw water discharged by the pump 5 is supplied through the water supply pipe 9 and the valve 14. The water supplied to the membrane degassing device 1 is made to flow through one chamber partitioned by the degassing membrane 2, and the other part of the raw water discharged by the pump 5 is driven by the ejector 6 through the drive water pipe 8 and the valve 13. To the side to drive the ejector 6 to depressurize the other chamber partitioned by the degassing membrane 2 via the suction pipe 7. In addition,
The flow rate of the raw water supplied to the membrane deaerator 1 is adjusted by the valve 14, and the flow rate of the raw water supplied to the ejector 6 is controlled by a vacuum gauge (not shown) attached to the suction pipe 7, for example. Adjust with valve 13 to the desired degree.

By such an operation, the other chamber partitioned by the degassing membrane 2 is in a depressurized state, and only the gas in the raw water flowing through the degassing membrane 2 into the one chamber is sucked into the other chamber and oxygen Alternatively, deaerated water from which most of dissolved gas such as free carbonic acid is removed is obtained from the deaerated water pipe 11. The gas-liquid mixed water mixed with the gas thus removed is blown, but it may be recovered in the raw water tank 10 in some cases. When the blow water is collected in the raw water tank 10, it is preferable to use a relatively large raw water tank 10 having a capacity capable of releasing dissolved gas excessively dissolved in the blow water into the atmosphere.

Next, the degassed water obtained from the degassed water pipe 11 from which most of the gas such as dissolved oxygen has been removed is passed through the deoxidizing device 3 in the subsequent stage. In the deoxidizing apparatus 3, deaerated water comes into contact with the deoxygenating resin 4 which is filled inside and made of a weakly basic anion exchange resin holding reducible copper, so that its strong reducing action is achieved. The trace amount of dissolved oxygen remaining in the degassed water is removed by the
Treated water of 10 ppb or less can be easily obtained through the treated water pipe 11.

The degassing membrane used in the membrane degassing apparatus of the present invention may be any membrane as long as it has a property of allowing gas to pass but not liquid, such as a membrane made of tetrafluoroethylene, polyethylene, polypropylene or the like. 0.01μ as pore size
It is possible to use a so-called water-repellent porous membrane having a large number of pores of about m to 10 μm, or a known membrane having no pore but having a property of allowing only gas to permeate, such as a silicone rubber membrane. The shape may be hollow fiber, spiral, tubular film, flat film, or the like.

In addition, usually, using a hollow fiber-shaped or tubular membrane-shaped degassing membrane,
Water is passed from one end to the inside of the tube as one of the chambers described above on the inside of these tubes, and gas is discharged from the inside to the outside of the tubes by decompressing the outside of the tubes as the other chamber described above by an ejector. It is configured to be removed and the deaerated water is taken out from the other end of the tube.

The deoxidizing resin used in the deoxidizing apparatus of the present invention is, for example, a weakly basic anion exchange resin having reducible copper (monovalent copper or metallic copper) retained thereon, or a strongly basic anion. Sulfite type or acidic sulfite type of the exchange resin, and further a strongly basic anion exchange resin having palladium supported on the surface (for example,
Known materials such as Bayer Corporation's Revachit OC1045) can be used.

Among the deoxygenating resins of the above examples, a weakly basic anion exchange resin that retains reducing copper and a strong basic anion exchange resin of a sulfite type or an acidic sulfite type are reducing copper or sulfurous acid, and an acidic sulfite of It is intended to remove dissolved oxygen in water by the reducing action, and the dissolved oxygen can be removed by simply bringing the water to be treated into contact with these resins. However, in the case of a deoxygenation resin in which palladium is supported on the surface of a strongly basic anion exchange resin, dissolved oxygen in water and hydrogen dissolved from the outside in the water are reacted with water by reacting the palladium as a catalyst. By doing so, dissolved oxygen is removed. Therefore, in this case, hydrogen to be reacted must be added and dissolved from the outside and then contacted with the deoxidizing resin.

In addition, it is usually good to use a weakly basic anion exchange resin that retains reducing copper as a deoxidizing resin.In the case of a sulfite type or acidic sulfite type strongly basic anion exchange resin, it retains reducing copper. The deoxygenating capacity is slightly inferior to the above-mentioned resin, and in the case of a strongly basic anion exchange resin supporting palladium, when dangerous hydrogen must be handled and unreacted hydrogen remains in the treated water. In addition, there is a slight drawback that the treatment becomes a problem.

It is also possible to install an ion exchange device such as a mixed bed polisher in the subsequent stage of the deoxidizing device filled with the deoxidizing resin to further remove the ionic impurities in the water.

<Effect> The device of the present invention has the above-mentioned configuration and operation,
Treated water with a dissolved oxygen concentration of, for example, 10 ppb or less can be easily obtained by the device, and therefore, cleaning water for semiconductor wafers that dislike the generation of oxide films and microorganisms, medical water,
It can be suitably used for producing various types of water such as water for advanced analysis.

The membrane degassing device in the device of the present invention serves as a device for rough-dissolving dissolved oxygen, and it suffices to reduce the dissolved oxygen concentration in water to about several hundred ppb by the membrane degassing device. It is not necessary to lower the dissolved oxygen to the limit, and therefore the vacuum device used can be smaller and less expensive than the case where treated water with a low dissolved oxygen concentration is obtained only by a membrane degassing device, and further degassing in the latter stage is possible. In the oxygen device, the degassed water with the dissolved oxygen concentration reduced by the membrane degassing device at the previous stage can be treated, so the load on the deoxygenating resin is significantly less than when treating the raw water directly with the deoxidizing device alone. Therefore, the life of the deoxidizing resin is significantly extended.

Further, when compared with the conventional method using a combination of a membrane degassing device and a nitrogen purging device, the device of the present invention does not require a wide aeration space required for the nitrogen purging device, and the supply of nitrogen required for aeration is required. Since the apparatus is not required, the entire apparatus can be made compact, and when the nitrogen cylinder is used as the nitrogen supply apparatus, the maintenance trouble such as the periodic replacement of the nitrogen cylinder is released.

Further, since the membrane degassing apparatus of the present invention uses the ejector as the vacuum device and the ejector is driven by using the pump for supplying the raw water to the membrane degassing apparatus, the pump for driving the ejector is used. It is economically advantageous because there is no need to separately provide it and an expensive vacuum pump is not required.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of an embodiment of the device of the present invention, and FIG. 2 is a flow chart showing an example of a conventional device. 1 ... Membrane degassing device, 2 ... Degassing film 3 ... Deoxidizing device, 4 ... Deoxidizing resin, 5 ... Pump, 6 ... Ejector, 7 ... Suction pipe, 8 ... Driving water pipe, 9 ... Water supply pipe, 10 …… Raw water tank 11 …… Degassing water pipe, 12 …… Treated water pipe 13, 14 …… Valve

Claims (1)

(57) [Scope of utility model registration request] 1. A membrane degassing apparatus equipped with a degassing membrane for removing dissolved gas such as oxygen dissolved in raw water, and remains in degassed water which is treated water of the membrane degassing apparatus. A dissolved oxygen removing device comprising a deoxidizing device filled with a deoxidizing resin for further removing a trace amount of dissolved oxygen, wherein a water supply pipe is provided in one chamber partitioned by the degassing membrane of the membrane deaerating device. It has a pump for supplying raw water through it and an ejector for decompressing the other chamber partitioned by a degassing membrane, and connects the drive water side of the ejector with the drive water pipe branched from the water supply pipe. Dissolved oxygen removal device characterized in that