JP2001000986A - Ozone injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the consumption of raw material gas and to reduce running cost in the treatment of waste liquid by circulating air after aeration to mix the same with the raw material gas. SOLUTION: Raw material gas is supplied to an ozone generator 2 from an oxygen cylinder 1 and a part of oxygen is changed to ozone in the ozone generator 2 by the silent discharge of the raw material gas. The formed ozone gas is injected in the waste liquid supplied to an aeration tank 3 through an air diffusing pipe 4 to perform aeration. Herein, an injector 7 is used in the suction and mixing of air after aeration. Negative pressure is generated in a circulating line 5 corresponding to the flow velocity of the raw material gas and a part of air after aeration is guided to the injector 7 to be mixed with the raw material gas. The mixing ratio of the raw material gas and the circulated air is adjusted by a damper 6. Excessive air is discharged from a vent piping 8. By this constitution, the injection amt. of ozone in the waste liquid is made constant and, when operation is performed so that the mixing ratio of the raw material gas and circulated air becomes 1:1, the raw material gas can be conserved to 1/2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating radioactive waste liquid containing a surfactant and an organic solvent, and more particularly to an ozone injection system using ozone as an oxidizing agent for decomposing organic components.

[0002]

2. Description of the Related Art In a nuclear power plant, radioactive waste liquid containing a surfactant, such as washing waste liquid for work clothes and hand washing waste liquid, is generated. This waste liquid is discharged outside the facility after removing or oxidatively decomposing organic substances such as surfactants contained therein and removing radioactive cladding and the like.

As a method of removing or oxidatively decomposing an organic substance, there is a method of performing a filtration treatment after adsorbing the organic substance by activated carbon powder as disclosed in Japanese Patent Application No. 8-165601.

[0004] As disclosed in Japanese Patent Application No. 10-170695, there is a method in which ozone gas is aerated to a waste liquid to dissolve ozone in the waste liquid and then irradiated with ultraviolet rays to decompose organic substances.

There is also a method in which hydrogen peroxide is added to the waste liquid, and ozone gas is aerated to the waste liquid under a heating condition to decompose organic substances.

[0006]

In the above-mentioned first known example, the used activated carbon becomes secondary waste, and a treatment facility for the activated carbon is required. In the second and third known examples, no secondary waste is generated, but in order to increase the dissolution rate of ozone in the waste liquid, a silent discharge using oxygen-enriched air or pure oxygen as a source gas is performed. There is a need to produce high concentrations of ozone. Therefore, there is a problem that the running cost for the source gas is increased.

An object of the present invention is to reduce the consumption of raw material gas and reduce the running cost of waste liquid treatment in a treatment system for injecting ozone into waste liquid.

[0008]

A first feature of the present invention to achieve the above object is that a radioactive waste liquid containing organic substances is aerated with ozone generated by silent discharge of oxygen gas or oxygen-enriched air as a raw material gas. In the treatment method for dissolving ozone in waste liquid, the gas after aeration is circulated and mixed with the raw material gas.

Usually, when producing ozone by silent discharge of oxygen gas or oxygen-enriched air as a raw material gas, the ozone concentration in the generated ozone gas is at most 20.
About volume percent, the balance being oxygen gas or oxygen-enriched air. Most of the ozone changes its form into oxygen by reaction with organic matter and water in the waste liquid. Therefore, the oxygen concentration in the gas after aeration of the waste liquid is as high as that of the source gas, and the gas can be reused as the source gas. Therefore, by circulating a part of the gas after aeration and mixing and supplying it to the source gas, it is possible to reduce the consumption of the source gas according to the mixing ratio.

A feature of the second invention that achieves the above object is that a radioactive waste liquid containing an organic substance is aerated with ozone generated by silent discharge using oxygen gas or oxygen-enriched air as a raw material gas, and ozone is contained in the waste liquid. In the dissolving treatment method, the gas after aeration is used as a raw material gas, and the ozone generated by the silent discharge is aerated to the waste liquid.

The operation of the present invention is the same as that of the first invention,
This is suitable for simplifying the operation of mixing the raw material gas and the circulating gas and configuring an ozone injection system as a backup system.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG.

A raw material gas is supplied from an oxygen cylinder 1 to an ozone generator 2. In the ozone generator, part of oxygen is changed to ozone by silent discharge of the raw material gas. The generated ozone gas is injected into the waste liquid supplied to the aeration tank 3 through the diffuser 4. In the embodiment of FIG. 1, suction of gas after aeration,
For mixing, an ejector 7 is used. A negative pressure is generated in the circulation line 5 according to the flow rate of the raw material gas, and a part of the gas after aeration is guided to the ejector and mixed with the raw material gas.
The mixing ratio between the source gas and the circulating gas is adjusted by the damper 6. Excess gas is exhausted from the vent pipe 8.

In this embodiment, when the mixing ratio of the source gas and the circulating gas is set to 1: 1 while the amount of ozone injected into the waste liquid is kept constant, the source gas can be reduced by half. It is preferable to put a filter of a dehumidifier or activated carbon in the circulation line 5 to remove moisture and impurities in the circulation gas. As the raw material gas, in addition to the high-pressure gas of oxygen, oxygen gas generated from a liquid oxygen vaporizer, oxygen-enriched air from a pressure swing adsorption device, and the like can be used.

A second embodiment of the present invention will be described with reference to FIG.

A raw material gas is supplied from an oxygen cylinder 1 to an ozone generator 2. In the ozone generator, part of oxygen is changed to ozone by silent discharge of the raw material gas. The generated ozone gas is injected into the waste liquid supplied to the aeration tank 3 through the diffuser 4. The gas after the aeration is supplied to another ozone generator 10 through the intake blower 9 and the silent discharge thereof causes
Some of the oxygen in the gas changes to ozone. The generated ozone gas is injected into the waste liquid supplied to the aeration tank 3 via another air diffuser 11. Excess gas is exhausted from the vent 12.

In the present embodiment, if the flow rate of the raw material gas is equivalent to the flow rate of the source gas and the re-ozone is injected, the ozone aeration amount to the waste liquid becomes 2
And the waste liquid treatment time can be reduced. As a result, source gas can be saved.

[0018]

According to the present invention, in a waste liquid treatment system using ozone gas, the source gas for producing ozone gas can be saved, and the operating cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart of an ozone injection system according to an embodiment of the present invention.

FIG. 2 is a flowchart of an ozone injection system according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Oxygen cylinder, 2, 10 ... Ozone generator, 3 ... Aeration tank, 4, 11 ... Aeration tube, 5 ... Circulation line, 6 ... Damper,
7: ejector, 8, 12: vent, 10: intake blower.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Matsumoto 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in the Electric Power & Electronics Development Division, Hitachi, Ltd. 4D050 AA13 AB02 AB07 BB02 BD02 BD03 BD04 BD06 BD08 4G035 AA01 AE13 4G042 AA07 CA01 CB12 CE04

Claims (2)

[Claims] An oxygen gas, a radioactive waste liquid containing organic matter,
Alternatively, in a processing method in which ozone generated by silent discharge of oxygen-enriched air as a raw material gas is used to dissolve ozone in a waste liquid, the gas after the aeration is circulated and mixed with the raw material gas. Injection system. 2. A radioactive waste liquid containing an organic substance, wherein oxygen gas,
Alternatively, in a treatment method in which ozone generated by silent discharge of oxygen-enriched air as a source gas is dissolved and ozone is dissolved in waste liquid, ozone generated by the silent discharge is aerated to waste liquid using the gas after aeration as a source gas. Ozone injection system characterized by performing.