JPH0994572A - Method for treating organic matter-containing water and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively treat org. matter without requiring large energy by setting the ultraviolet irradiation treatment condition to org. matter-containing water on the basis of the change in the conductivity of treated water caused by an ionic intermediate product formed from org. matter by the irradiation with ultraviolet rays. SOLUTION: Org. matter-containing water enters an ultraviolet irradiation apparatus 2 by a liquid supply pump 1 to be irradiated with ultraviolet rays while flows through the passage thereof and org. matter is decomposed to an ionic intermediate product and this product enters an ion exchange resin tower 4 to be subjected to ion exchange treatment and removed. Herein, the change in the conductivity of treated water by the irradiation with ultraviolet rays is measured by a conductivity meter 3 and, by an ultraviolet irradiation condition control unit 5 receiving the signal of the conductivity meter 3, the liquid supply amt. of the liquid supply pump 1 or the powder of an ultraviolet lamp is controlled so that the conductivity of ultraviolet treated water shows the max. value. Since the irradiation with ultraviolet rays is performed under a condition more forming the ionic intermediate product, the org. matter can be removed in the stage of the intermediate product without being finally decomposed to carbon dioxide and water and can be efficiently treated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating organic matter-containing water, and more particularly, a method and apparatus for treating water containing organic matter eluted from a condensate desalination unit or a filter desalting unit in a nuclear power plant. Regarding

[0002]

Power plants are operated in high temperature, high pressure steam conditions. On the other hand, most of the system equipment and pipes of the power plant are made of steel, and high-purity water from which impurities have been removed is used as condensate to prevent corrosion of the constituent materials. In particular, in boiling water nuclear power plants, impurities contained in condensate are brought into the reactor and promote corrosion of the structural materials inside the reactor. Therefore, a desalting device is installed in the condensate system to thoroughly remove impurities. As the desalting device, a filter desalting device using a powder ion exchange resin and a desalting device using a granular ion exchange resin are provided. As another conventional example, Japanese Patent Laid-Open No. 4-3
No. 34588 or Japanese Patent Application Laid-Open No. 6-138289 is disclosed, which discloses irradiating ultraviolet rays to decompose organic substances in the condensate.

[0003]

A desalting device using an ion exchange resin has excellent ability to remove ionic impurities, but does not have ability to remove nonionic impurities such as organic substances such as alcohol. Further, since the ion exchange resin used in the desalting device uses a copolymer of styrene and divinylbenzene as a resin matrix, elution of organic substances from the ion exchange resin itself cannot be avoided. As leaching organic substances, polystyrene sulfonic acid is known as a cation exchange resin, and trimethylamine, methanol, polystyrene quaternary ammonium as an anion exchange resin are known. Therefore, there is a problem that nonionic organic substances in the condensate or organic substances eluted from the desalting device itself are brought into the reactor and decomposed to generate sulfate ions and nitrate ions. Further, in the method of irradiating ultraviolet rays such as JP-A-4-334588 to decompose organic matter in the condensate, the organic matter is completely decomposed into final carbon dioxide gas and water by the ultraviolet ray irradiation. There was a problem that it required large amount of energy and was not economical.

An object of the present invention is to solve the above-mentioned problems in condensate purification of a nuclear power plant and the like, and to provide an effective method and apparatus for treating water containing organic matter, which is effective and does not require large energy for decomposing organic matter. To provide.

[0005]

In order to achieve the above object, the present invention provides the conditions for ultraviolet irradiation treatment of organic matter-containing water such that the organic matter in the treated water is an ionic intermediate product produced by ultraviolet irradiation. The method for treating organic matter-containing water is characterized in that it is set on the basis of the change in conductivity.

Another aspect of the present invention is characterized in that, in the above-mentioned invention, the ultraviolet irradiation treatment condition of the organic matter-containing water is set so that the conductivity increases by changing the irradiation time of ultraviolet rays.

Another aspect of the present invention is characterized in that, in the above invention, the ultraviolet irradiation treatment condition of the organic matter-containing water is set so that the electric conductivity increases by changing the electric power of the ultraviolet lamp.

Another aspect of the present invention is the method for treating organic matter-containing water according to any one of the above aspects, characterized in that the treated water in a state where an ionic intermediate product is produced is subjected to an ion exchange treatment.

According to another invention, in any one of the above inventions, the organic substance-containing water is an organic substance-containing water that is eluted from a desalting device that is mixed and filled with a granular cation exchange resin and an anion exchange resin. It is a method of treating organic matter-containing water.

According to another invention, in any one of the above inventions, the organic matter-containing water is an organic matter-containing water that is eluted from a filter desalting device precoated with powdered cation exchange resin and anion exchange resin. To do.

According to another aspect of the invention, a liquid feeding means for feeding organic matter-containing water as treated water, an ultraviolet ray irradiating means for irradiating the treated water fed from the liquid feeding means with ultraviolet rays, and the ultraviolet ray irradiating means are passed through. Ion exchange means to which the treated water is sent, conductivity detection means provided between the ultraviolet irradiation means and the ion exchange means for detecting the conductivity of the treated water subjected to the ultraviolet irradiation treatment, and the conductivity detection means An apparatus for treating organic matter-containing water, comprising: an ultraviolet ray irradiation condition control unit for setting an ultraviolet ray irradiation treatment condition for the treated water in a direction in which the conductivity thereof increases in response to a detection signal.

According to another aspect of the invention, in the above invention, the detection signal of the conductivity detecting means is sent to the ultraviolet irradiating means to change and control the ultraviolet lamp power.

According to another invention, in the above invention, the detection signal of the conductivity detecting means is sent to the liquid feeding means and the irradiation time of the ultraviolet rays is changed and controlled.

According to the present invention, when organic matter-containing water such as condensate of a power plant is irradiated with ultraviolet rays and then subjected to an ion exchange treatment, the organic matter is decomposed into an ionic intermediate product by the irradiation of ultraviolet rays, and the ionic intermediate product is decomposed. Although the conductivity of the treated water changes based on the generation of the, the optimum ultraviolet irradiation conditions are set based on the change in the conductivity. As a result, the organic substance-containing water can be efficiently treated without requiring a large amount of energy for decomposing the organic substance.

The present inventors have conducted various studies on a method for purifying condensate of a power plant in order to improve the performance of the power plant and prevent corrosion of constituent equipment. Sodium ions and chlorine ions, which are one of the corrosive components contained in the condensate, are removed by a desalting device in which a cation exchange resin and an anion exchange resin are mixed and filled. However, as described above, the organic matter in the condensate and the organic matter eluted from the ion exchange resin of the desalting device cannot be removed. Here, the amount of organic substances eluted from the ion-exchange resin of the desalting device is small in a normal running water state because the residence time of the condensate water in the desalting device is very short, and there is almost no problem. However, when the condensate demineralizer is backwashed, regenerated and the condensate filtration desalinator is pre-coated, it is out of service from the condensate system, and after these operations are completed, it waits until the next water flow. Since such a state takes a long time, the organic matter eluted from the ion-exchange resin in the desalting device has a high concentration, and a large amount of organic matter is brought into the condensate during in-service. All of these are brought into the reactor and decomposed to produce impurity ions. In order to prevent this, at present, bottom drain water is unavoidably discharged to the outside of the system before in-service of the desalinizer. However, the bottom drain water containing this organic matter is recovered and returned to the condensate as makeup water. Therefore, organic matter in the bottom drain water of the desalting device or the like will eventually enter condensate unless it is decomposed and removed. In order to prevent such a situation, it is necessary to decompose and remove organic substances such as bottom drain water.

As a method for decomposing and removing organic substances, ultraviolet irradiation treatment which does not require addition of a chemical agent such as an oxidizing agent is preferable. In this method, a low-pressure mercury lamp having main wavelengths of 185 nm and 254 nm is used to irradiate ultraviolet rays to oxidize and decompose organic substances. In particular, the light of 185 nm decomposes water molecules to generate hydroxy radicals having a strong oxidizing power, and dissociates chemical bonds of dissolved organic substances in water. By these actions, the organic matter is finally decomposed into carbon dioxide gas and water. However, a large amount of energy is required to completely decompose organic matter into carbon dioxide and water. Here, the organic matter is decomposed into carbon dioxide gas and water through various intermediate products depending on the degree of oxidative decomposition when it is irradiated with ultraviolet rays.

By the way, the intermediate product is mainly an ionic substance such as an organic acid such as formic acid or acetic acid, which can be removed by an ion exchange resin. According to our study results, if ultraviolet irradiation of organic matter-containing water is performed under the condition that more ionic intermediate products are produced, and then ion exchange treatment is performed,
It was found that the organic matter can be removed at the intermediate product stage without being decomposed into the final carbon dioxide gas and water, and the treatment of the organic matter-containing water can be performed efficiently. The type and amount of the intermediate product produced by the irradiation of the organic substance with ultraviolet light depends on the concentration of the organic substance, the ultraviolet irradiation time, the ultraviolet irradiation amount, and the like. In order to efficiently treat the organic matter-containing water by such a method, the organic matter-containing water may be irradiated with ultraviolet rays so that the conductivity of the ultraviolet ray-treated water becomes maximum.

Further, the ultraviolet irradiation treatment condition of the organic substance-containing water can be easily set by changing the irradiation time of the ultraviolet light so as to increase the conductivity by changing the liquid feed amount of the liquid feed pump or the like. Alternatively, it is possible to easily set the ultraviolet irradiation amount in the direction in which the conductivity increases by changing the power of the ultraviolet lamp.

Further, according to the treatment apparatus for organic substance-containing water according to the present invention, the invention relating to the treatment method can be carried out with a simple structure. Particularly, the detection signal of the conductivity detection means is sent to the ultraviolet irradiation means to change and control the ultraviolet lamp power, and the detection signal of the conductivity detection means is sent to the liquid feeding means to change and control the irradiation time of ultraviolet rays. What is done is structurally simple.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

Specific Example 1 Next, the present invention will be specifically described with reference to FIG. FIG. 1 is a block diagram of an apparatus for treating organic matter-containing water according to the present invention. This organic substance-containing water treatment device is composed of a liquid feed pump 1, an ultraviolet irradiation device 2, a conductivity meter 3, an ion exchange resin tower 4, and an ultraviolet irradiation condition control device 5. As shown in FIG. 2, the ultraviolet irradiation device 2 is composed of an ultraviolet lamp 6 and an organic substance-containing water flow path 7. UV lamp 6
Is preferably a low-pressure mercury lamp with dominant wavelengths of 185 nm and 254 nm. In this embodiment, the ion exchange resin tower 4 is a mixture of a cation exchange resin and an anion exchange resin. Further, the ultraviolet irradiation condition control device 5 measures the conductivity of the ultraviolet irradiation treated water that has passed through the ultraviolet irradiation device 2 with the conductivity meter 3, and adjusts the liquid feed amount of the liquid feed pump 1 so as to maximize the conductivity. It controls the electric power of the ultraviolet lamp of the ultraviolet irradiation device 2. Changing the amount of liquid sent by the liquid sending pump 1 corresponds to changing the irradiation time of ultraviolet rays. Although it is possible to control both the liquid delivery amount and the ultraviolet lamp power,
It is usually good to control only one of them.

The steps in FIG. 1 will be described. The organic substance-containing water enters the ultraviolet ray irradiation device 2 by the liquid feed pump 1, is irradiated with ultraviolet rays while the organic substance-containing water flows through the flow path 7, and the organic substance is decomposed into an ionic intermediate product. Next, it enters the ion-exchange resin tower 4 and is ion-exchanged and removed. Here, a change in conductivity of treated water due to ultraviolet irradiation is measured by a conductivity meter 3, and an ultraviolet irradiation condition control device 5 which receives the signal controls the liquid feed amount of a liquid feed pump and the ultraviolet lamp power to perform the ultraviolet treatment. The conductivity of water shows the maximum value. A flowchart of this processing method is as shown in FIG.

Next, an example of treatment by the treatment apparatus for organic substance-containing water of FIG. 1 will be shown. The organic substance-containing water contains organic substances eluted from the mixed state of the cation exchange resin and the anion exchange resin. Organic matter concentration of this treated water (TOC: Total
Organic Carbon) is 1200 μg / l, conductivity is 3.5
μS / cm. By changing the flow rate of the liquid feed pump 1, the irradiation time in the ultraviolet irradiation device 2 was changed and processing was performed. Subsequently, an ion exchange treatment was performed by the ion exchange resin tower 4. FIG. 4 shows the conductivity and TOC after the ultraviolet irradiation treatment. As the irradiation time increases, the conductivity increases, reaches a maximum near the irradiation time of 3 minutes, and thereafter decreases and becomes constant. This is considered to be because ionic intermediates are first generated by the irradiation of ultraviolet rays, and then these are oxidatively decomposed to generate carbon dioxide gas and water. The TOC decreases as the irradiation time increases, and becomes 100 μg / l or less after the irradiation time of 6 minutes, showing that the organic substances are completely decomposed into carbon dioxide gas and water. On the other hand, at this time, the water quality of the ion-exchange treated water by the ion-exchange resin tower 4 installed in the latter stage of the ultraviolet irradiation treatment is TOC 100 μg / l or less and conductivity 0 or less at the irradiation time of 3 minutes or longer at which the conductivity is maximized by the ultraviolet irradiation. .1 μS /
cm or less, and both organic substances and ions were sufficiently removed.

[Specific Example 2] FIG. 5 is a system diagram of a system of a nuclear power plant and a treatment system of organic substances eluted from a desalination unit. In FIG. 5, 8 indicates a bottom drain water recovery tank of the desalting device 10, and 9 indicates a treatment device for organic substance-containing water according to the present invention. The desalinizer 10 is mixed and filled with granular cation exchange resin and anion exchange resin. In addition, filter desalting machine 1
1 is pre-coated with powdered cation exchange resin and anion exchange resin. The bottom drain water of the desalting device 10 and the filter desalting device 11 is recovered, and the organic substance-containing water treatment device 9
After being treated by, it is reused as make-up water for the plant.

[0024]

EFFECTS OF THE INVENTION According to the present invention, the irradiation of the organic matter-containing water with ultraviolet rays is performed under the condition that more ionic intermediate products are produced, and then the ion exchange treatment is performed, so that the organic matter is finally converted into carbon dioxide gas and water. It can be removed at the stage of an intermediate product without decomposition, and the organic substance-containing water can be efficiently treated, and a large amount of energy is not required to decompose the organic substance. As a result, the organic matter in the condensate of the nuclear power plant is reduced, it is possible to prevent it from being brought into the reactor, the corrosion of reactor internals, etc. is reduced, the performance of the power plant is improved, and the life of the equipment is extended. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus for treating organic matter-containing water according to the present invention.

FIG. 2 is a vertical sectional view of an ultraviolet irradiation device.

FIG. 3 is a flowchart of a processing method of the present invention.

FIG. 4 is an example of ultraviolet irradiation treatment of organic matter-containing water by the method for treating organic matter-containing water according to the present invention, showing the relationship between conductivity and TOC with respect to ultraviolet ray irradiation time.

FIG. 5 is a configuration diagram showing a condensate system of a nuclear power plant equipped with the present organic matter-containing water treatment apparatus.

[Explanation of symbols]

 1 Liquid Delivery Pump 2 Ultraviolet Irradiation Device 3 Conductivity Meter 4 Ion Exchange Resin Tower 5 Ultraviolet Irradiation Condition Control Device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G21D 1/00 GDB G21F 9/12 512C G21F 9/12 512 G21C 19/30 GDBC G21D 1/00 GDBW (72) Inventor Tsutomu Yamano 3-2-2 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi Engineering Service (72) Inventor Naoshi Usui 3-2-1 Sachimachi, Hitachi City, Ibaraki Hitachi Engineering Co., Ltd. Incorporated (72) Inventor Yamato Asakura 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory

Claims (9)

[Claims] 1. A method for treating organic matter-containing water, comprising irradiating an organic matter-containing water with ultraviolet rays to treat the organic matter-containing water with ultraviolet rays, wherein the organic matter in the treated water is based on an ionic intermediate product produced by ultraviolet ray irradiation. A method for treating organic matter-containing water, which is set based on a change in conductivity of the treated water. 2. The method for treating organic matter-containing water according to claim 1, wherein the conditions for irradiating the organic matter-containing water with ultraviolet rays are set so that the conductivity increases by changing the irradiation time of ultraviolet rays. 3. The method for treating organic matter-containing water according to claim 1, wherein the ultraviolet ray irradiation treatment condition for the organic matter-containing water is set in such a direction that the electric conductivity is increased by changing the electric power of the ultraviolet lamp. 4. The method for treating organic matter-containing water according to claim 1, wherein the treated water in a state where the ionic intermediate product is produced is subjected to an ion exchange treatment. 5. The organic substance-containing water according to claim 1, wherein the organic substance-containing water is an organic substance-containing water that is eluted from a desalting device that is mixed and filled with a granular cation exchange resin and an anion exchange resin. A method for treating organic matter-containing water. 6. The organic matter-containing water according to any one of claims 1 to 4, wherein the organic matter-containing water is an organic matter-containing water that is eluted from a filter desalting device precoated with powdered cation exchange resin and anion exchange resin. A method for treating organic matter-containing water. 7. A liquid feed means for feeding organic matter-containing water which is treated water, an ultraviolet ray irradiating means for irradiating the treated water fed from this liquid feed means with ultraviolet rays, and a treated water which has passed through this ultraviolet ray irradiating means is fed. An ion exchange means, a conductivity detection means provided between the ultraviolet irradiation means and the ion exchange means for detecting the conductivity of the treated water subjected to the ultraviolet irradiation treatment, and a detection signal of the conductivity detection means. And an ultraviolet irradiation condition control means for setting ultraviolet irradiation processing conditions for the treated water in a direction in which the conductivity increases. 8. A treatment apparatus for organic substance-containing water according to claim 7, wherein the detection signal of the conductivity detecting means is sent to the ultraviolet irradiating means to change and control the power of the ultraviolet lamp. 9. The apparatus for treating organic matter-containing water according to claim 7, wherein the detection signal of the conductivity detecting means is sent to the liquid feeding means and the irradiation time of the ultraviolet rays is changed and controlled.