JPS6214097A - Microwave heating evaporator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for reducing the volume and decontaminating radioactive liquid waste such as nitric acid used in the process of reprocessing spent nuclear reactor fuel. The present invention relates to a device for heating and evaporating , and particularly to a microwave heating evaporation device that uses microwaves as a heating source.

(Prior Art) As a heating evaporation device for volume reduction and decontamination of radioactive liquid waste, one having the configuration shown in FIG. 2 has been known.

In FIG. 2, radioactive liquid waste is supplied into the evaporator 1 from the lower liquid supply port 4. A multi-tube heat exchanger 7 is installed in the evaporator 1, and the radioactive liquid waste is heated by exchanging heat with steam introduced from the steam port 8, and thereby evaporated. Condensed water generated during this heat exchange is discharged from the condensed water outlet 9.

The radioactive liquid waste heated and evaporated as described above in the evaporator 1 is connected! ! 3 into a cylindrical flash chamber 2 where it is separated into a vapor phase and a liquid phase. The separated vapor phase is led to the next step through the steam outlet 6, and the liquid phase of condensed water is recovered through the condensed water outlet 5. Note that a collision baffle plate 10 and a demister 11 are provided within the flash 2.

[Problem that the invention seeks to solve]

Such heating evaporates'! , H, if the radioactive liquid waste is nitric acid or the like, there is a problem of corrosion inside the evaporator 1.

In particular, in conventional equipment, the multi-tubular heat exchanger 7 inside the evaporator 1 has many welded parts, so there is a high possibility of corrosion, and there was a risk that radioactive liquid waste could leak through pinholes caused by corrosion. .

Also, multi-tube heat exchange! No. 17 has a small inner diameter of the tube, so there is also the problem of significant scale formation. Therefore, it is necessary to periodically remove the generated scale, making maintenance very complicated.

The present invention was made to solve these conventional problems, and its purpose is to provide a microwave heating evaporation device that is less likely to be corroded by radioactive liquid waste and that produces less scale. It is in.

[Means for solving problems]

The microwave heating evaporator according to the present invention includes an evaporator into which radioactive liquid waste is supplied from the lower part and which heats and evaporates the waste; A flash chamber that separates the phase and a microwave generator that generates microwaves to heat the waste in the evaporator! and means for guiding the microwaves generated by the microwave generator into the evaporator.

That is, the present invention uses a microwave generator as a heating source for evaporating radioactive liquid waste.

[Effect]

In the present invention, 1 flf of microwaves are guided into the evaporator via a waveguide or the like, and are irradiated onto the radioactive liquid waste introduced into the evaporator from the bottom. As a result, the radioactive liquid waste is heated and vaporized by the dielectric heating effect of the microwaves. The evaporated radioactive liquid waste is then separated into a vapor phase and a liquid phase in a flash chamber, as is conventional.

〔Example〕

Hereinafter, the present invention will be explained in detail based on an embodiment shown in FIG.

As shown in FIG. 1, the evaporator 1 is not provided with a shell-and-tube heat exchanger like the conventional one (FIG. 2), but instead the microwave is transmitted from the microwave generator 12 through the waveguide 13. The configuration is such that microwaves are supplied into the evaporator 1 from a microwave transmission window 15 provided at the top of the evaporator 1. Note that a matching device 14 for impedance matching is attached to the waveguide 13 through which the microwave propagates.

When microwaves are supplied into the evaporator 1 in this way, the 1ili supplied into the evaporator 1 from the lower liquid supply port 4 is
Radioactive liquid waste such as ll1 is heated and evaporated by dielectric heating using microwaves. The evaporated radioactive liquid waste is led to a flash chamber 2 connected to an evaporator 1 via a connecting pipe 3, as in the conventional case, and is separated into a vapor phase and a liquid phase. A collision baffle plate 1o and a demister 11 are provided within the flash chamber 2. The vapor phase separated in the flash chamber 2 is led to the next step through a vapor outlet 6 provided at the top of the flash chamber 2, and the liquid phase, that is, the condensate, is led to the next step through a condensate outlet provided at the bottom of the flash chamber 2. Collected from 5. As described above, radioactive liquid waste is heated and evaporated! 13! will be carried out.

〔Effect of the invention〕

As explained above, according to the present invention, dielectric heating using microwaves is used as a heating means for radioactive liquid waste, so it is possible to use dielectric heating using microwaves as a heating means for radioactive liquid waste. Not only is the structure of the evaporator chamber simpler than the conventional evaporator, but also there are no many welded parts in contact with high-temperature steam, which eliminates the problems of corrosion and holes in the evaporator chamber caused by radioactive liquid waste. resolved.

In addition, since microwaves are reflected by metal surfaces, the heated part in the evaporator is limited to the radioactive liquid waste, and there is a problem of corrosion due to heating of the metal surface when using a shell-and-tube heat exchanger. can be avoided. Therefore, in the present invention, it is possible to completely eliminate the risk of leakage of radioactive liquid waste.

In addition, since there is no need to use thin tubes as in a shell-and-tube heat exchanger, the generation of scale is significantly reduced, and maintenance for scale removal and the like is facilitated.

Furthermore, microwaves for heating can be efficiently supplied from the microwave generator to the evaporator using a waveguide, etc.
The microwave generator can be installed outside the radiation control area, which is also advantageous in terms of maintenance. Furthermore, it is also possible to remotely control the entire heating evaporation device via the microwave generator.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a microwave heating evaporation device according to the present invention, and FIG. 2 is a longitudinal sectional view of a conventional heating evaporation device. 1... Evaporator, 2... Flash chamber, 3... Connecting pipe, 4... Liquid supply port, 5... AM liquid outlet, 6... Steam outlet, 10... Collision obstruction Board, 11...Demister,
12... Microwave generator, 13... Waveguide, 1
4... Matching box. 15...Microwave transmission window. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] an evaporator into which radioactive liquid waste is supplied from the bottom and which heats and evaporates the waste; a flash chamber connected to the evaporator and which separates the vapor phase and liquid phase of the waste; and the evaporator. A microwave characterized by comprising: a microwave generator that generates microwaves for heating waste in a can; and means for guiding the microwaves generated by the microwave generator into the evaporator. Heating evaporation device.