JPH0339019B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a microwave denitrification apparatus, and more particularly to an improvement in a receiving container for containing a solution to be treated such as uranyl nitrate.

[Technical background of the invention]

During the reprocessing of spent nuclear fuel in nuclear reactor fronts, solutions such as uranyl nitrate are obtained.
This solution is then subjected to denitrification treatment in a microwave denitrification device.

As shown in FIG. 1, the microwave denitrification apparatus includes a turntable 2 provided at the bottom of an oven 1, a receiving container 3 placed on the turntable 2, and a solution 4 to be treated in the receiving container 3. A solution supply pipe 6 is provided, and a gas delivery pipe 8 is connected to send out steam, NOx gas, etc. generated in the oven 1 to a gas treatment system (not shown), and a waveguide is connected to the outside of the oven 1. a microwave oscillator 12 that directs microwave radiation into the oven 1 through 10;
It has a configuration with .

Therefore, when a solution 4 to be treated such as uranyl nitrate is supplied into the receiving container 3 through the solution supply pipe 6 and irradiated with microwaves from the microwave oscillator 12,
The solution 4 is heated and first undergoes the steps of evaporation of water and denitrification to obtain a desired powder material.

[Problems with Background Art] Stainless steel is generally used as the material for the receiving container 3 in consideration of thermal strength and prevention of contamination by impurities. Particularly when the solution to be treated is a nuclear material and is a nitric acid solution, it is desirable that the receiving container be made of metal such as stainless steel. However, metals such as stainless steel are not heated due to microwave interference on the surface, and on the contrary, the heating of the solution 4 to be treated is inhibited due to the heat dissipation effect. is not desirable.

[Purpose of the invention]

The present invention was developed based on the above circumstances, and its purpose is to be able to heat the solution to be treated even from the bottom of the receiving container, and also to obtain a heat retention effect, and as a result, to achieve a good denitrification effect. The object of the present invention is to provide a microwave denitrification device that can be obtained.

[Summary of the invention]

The microwave denitrification apparatus according to the present invention includes: a metal dish-shaped container that contains a solution to be treated; a microwave-transparent cover container that forms a sealed space on the lower side of the dish-shaped container; a liquid high dielectric constant substance sealed in the container; a safety valve that communicates the sealed space with the outside when the pressure inside the sealed space reaches a set pressure; The container is characterized by being equipped with a microwave oscillator that irradiates microwaves from above the container.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention shown in FIGS. 1 and 2 will be described. FIG. 1 shows a schematic configuration of a microwave denitrification device. A turntable 102 is provided on the bottom of an oven 101, a receiving container 103 is installed on this turntable 102, and a receiving container 103 is placed inside the receiving container 103. solution 10
A solution supply pipe 106 for supplying 4 is provided, and a gas delivery pipe 108 is further connected to send steam, NOx gas, etc. generated within the oven 101 to a gas treatment system (not shown). The configuration includes a microwave oscillator 112 that irradiates microwaves into the oven 101 through a wave tube 110.

As shown in FIG. 3, the receiving container 103 covers the lower side of a dish-shaped container 113 that accommodates the solution to be treated 104 with a cover container 114, and has a sealed space formed between the dish-shaped container 113 and the cover container 114. 115
A liquid having a high dielectric constant, such as water 116, is sealed inside. Further, the flange portion 114A of the cover container 114 includes an injection valve 118 for injecting water 116 into the sealed space 115, and a safety valve 1 for releasing steam generated in the sealed space 115.
20 are connected.

The dish-shaped container 113 is made of metal such as stainless steel. In addition, the cover container 114
is made of a material that is transparent to microwaves, such as Teflon (a trade name for polytetrafluoroethylene).

In the microwave denitrification apparatus configured as described above, the solution supply pipe 106 is passed through the receiving container 102.
Supplying a solution 104 to be treated such as uranyl nitrate,
When the microwave oscillator 112 is driven, the oscillator 1
Microwaves from 12 are irradiated toward the solution to be treated 104 . Therefore, the solution to be treated 104 is heated and denitrified from the upper surface side by being irradiated with microwaves, but the water 11 present on the lower surface side of the dish-shaped container 113
6 also has a high dielectric constant, so it is heated by the microwaves transmitted through the dish-shaped container 113, and the heat is transferred to the solution to be treated 104 via the dish-shaped container 113. Therefore, the solution to be treated 104 is heated from below as well, and the denitrification effect is significantly improved, especially in the vicinity of the liquid contact surface of the dish-shaped container 113, and a heat retention effect is also obtained.

Furthermore, the pressure in the sealed space 115 between the dish-shaped container 113 and the cover container 114 increases due to the heating of the water 116, but when the set pressure of the safety valve 120 is reached, this safety valve 120 opens to prevent the pressure from increasing any further. This prevents damage to the cover container 114.
Moreover, when reusing the receiving container 113, the water 116 can be replenished by opening the injection valve 118.

Next, a second embodiment shown in FIG. 4 will be described. The receiving container 122 of this embodiment has a cover container 126 that independently forms a closed space 124 attached to the lower surface side of a dish-shaped container 113 similar to that of the first embodiment. The same parts as those in the first embodiment are indicated with the same numbers.

With this configuration, the same effects as in the first embodiment can be obtained, and since the cover container 126 alone forms the closed space 124, the dish-shaped container 113
When combining the cover container 126 and the closed space 1
There is no need to consider the sealability of the containers 113 and 126, and therefore the work of joining both the containers 113 and 126 becomes easier.

Note that the present invention is not limited to the configurations of the first and second embodiments. For example, a screw plug may be provided in place of the injection valve 118, and the screw plug may be removed to replenish the water 116, and the screw plug may be provided with a safety valve. It is also possible to adjust the set pressure of the safety valve 120.

〔Effect of the invention〕

As described in detail above, the microwave denitrification apparatus according to the present invention includes a metal dish-shaped container that accommodates a solution to be treated, and a microwave-transparent cover that forms a sealed space on the bottom side of the dish-shaped container. a container, a liquid high dielectric constant substance sealed in the closed space,
A safety valve that communicates the sealed space with the outside when the inside of the sealed space reaches a set pressure, and a microwave oscillator that irradiates the solution to be processed contained in the dish-shaped container with a micro-liquid from above the dish-shaped container. This makes it possible to heat the solution to be treated from below the dish-shaped container, and also provides a heat retention effect, resulting in good denitrification effects, etc. , can have great effects.

In addition, in the present invention, the solution to be treated can be heated from the bottom side of the dish-shaped container using the microwaves that have passed through the dish-shaped container, so the surplus energy of the microwaves that was previously wasted can be used effectively. This can be used to reduce the input energy of microwaves.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional microwave denitrification device, FIGS. 2 and 3 show a first embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a microwave denitration device, and FIG. The figure is a longitudinal sectional view of a receiving container of the same device, and FIG. 4 is a longitudinal sectional view of a receiving container in a second embodiment of the present invention. 101... Oven, 103, 122... Receiving container, 104... Solution to be treated, 112... Microwave oscillator, 113... Dish-shaped container, 114, 12
6... Cover container, 115, 124... Closed space, 116... Water (high dielectric constant material), 120...
…safety valve.

Claims (1)

[Claims] 1. A metal dish-shaped container containing a solution to be treated;
A microwave-transparent cover container forming a sealed space on the lower side of the dish-shaped container, a liquid high dielectric constant material sealed in the sealed space, and a pressure inside the sealed space reaching a set pressure. A microwave denitrification device characterized in that it is equipped with a safety valve that communicates the sealed space with the outside, and a microwave oscillator that irradiates the solution to be treated contained in the dish-shaped container with a microfluid from above the dish-shaped container. Device. 2. The microwave denitrification device according to claim 1, wherein the dish-shaped container is made of stainless steel. 3. The microwave denitrification apparatus according to claim 1, wherein the cover container is made of Teflon (trade name). 4. The microwave denitrification device according to claim 1, wherein the high dielectric constant substance is water. 5. The microwave denitration apparatus according to claim 1, wherein the dish-shaped container and the cover container form a sealed space. 6. The microwave denitrification apparatus according to claim 1, wherein the cover container alone forms a sealed space.