JPS6082125A - Apparatus for concentrating hydrogen isotope by electrolysis of water - Google Patents

Abstract

PURPOSE:To concentrate hydrogen isotope with high efficiency by the electrolysis of water using an electrolytic cell wherein a part of the material contacting with liquid other than the cathode and anode is made of chromium and the material for the part contacting with liquid is insulated electrically from other parts but connected electrically with the cathode. CONSTITUTION:A diaphragmless electrolytic cell 1 is used in a concentration apparatus for hydrogen isotope basing on electrolysis of water. A vessel 4 made of Cr alloy insulated from the anode 2 by an insulating material 3 and insulated also from pipings or other parts is attached to the top of the cylindrical anode 2 plated with Ni on its inside surface contacting with liquid. A cylindrical cathode 5 made of iron is inserted from the bottom of the anode 2 confronting the inside surface of the anode 2 and is fixed to the bottom edge of the anode 2 interposing an insulating material 3. The vessel 4 is connected with a cathode 5 by a conductor 6. Same negative potential as the cathode 5 is impressed to the vessel 4, thus, dissolution of the Cr alloy into electrolytic liquid is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrogen isotope concentrator using electrolysis, which enables concentration of heavy water without reducing concentration efficiency over time.

Conventionally, hydrogen isotope concentrators using water electrolysis have used membraneless electrolyzers that operate in batches.If nickel or nickel plating is used as the anode material and carbon steel is used as the cathode material in these membraneless electrolyzers, the concentration efficiency can be improved. is known to be high. Various materials are used for other parts that come into contact with liquid, but when mechanical strength is required, carbon steel, which is usually inexpensive, is used. In this case, problems arise such as damage to the equipment due to iron corrosion or contamination of the liquid due to eluted metals.

In order to prevent corrosion, it is possible to prevent corrosion by using materials in contact with liquid other than the electrodes that have a smaller ionization tendency than the anode, but this is not economical as the cost of the device is high. Therefore, chromium or chromium-containing stainless steel may be considered, which is practically satisfactory in terms of corrosion resistance and is not very expensive.

By the way, by using the stainless steel fli', contamination of the electrolyte is significantly reduced, but the concentration efficiency gradually decreases as the number of concentration operations increases.

As a result, there was an inconvenience in that the production capacity of the heavy water concentrator was significantly reduced.

In view of the above circumstances, the present inventor conducted extensive research and discovered that the gradual decline in deuterium concentration efficiency is caused by heavy metals, particularly Cr, dissolved in extremely small amounts in the electrolyte.

The present invention was completed based on the above discovery, and its gist is that part or all of the material of the liquid contact parts other than the cathode and anode of the electrolytic concentration tank is made of chromium or a chromium alloy, and A hydrogen isotope concentrator by electrolysis of water, characterized in that a liquid part material is electrically insulated from others and electrically connected to the cathode.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows an embodiment of a non-diaphragm electrolytic cell I used in a hydrogen isotope concentrator by water electrolysis according to the present invention. Reference numeral 2 in the figure is a cylindrical anode whose inner surface liquid portion is nickel plated. A container 4 made of a chromium alloy, which is electrically insulated from the anode 2 by an insulating material 3 and also insulated from piping and the like, can be seen above the anode 2. Further, a cylindrical iron cathode 5 is inserted from the bottom of the anode 2 so as to face the inner surface of the anode 2, and is fixed to the lower end of the anode 2 via an insulating material 3.

The container 4 is connected to the cathode 5 by a conductor 6.

Moreover, FIG. 2 is a diagram showing a known hydrogen isotope electrolytic concentrator using the membraneless electrolytic cell 1 described above. In the figure, 11 is a storage tank for concentrated electrolyte, and 12 is a distillation column.

12a is a concentrator, 13 is a product tank, and 14 is a distillation column 1
Separated electrolyte 15 at the bottom of 2, raw material heavy water (degraded heavy water) 16 and recovered heavy water 1B discharged from the condensate system 17
19 is an electrolytic solution storage tank that stores the adjusted electrolytic solution and batch-fills it into the electrolytic concentration tank 1.The dotted line 20 indicates that the gas ( For example, H2. generated by circulating He.
This is a gas circulation system that sends D2 and 02 to the condensate system.

Next, the operation of the apparatus according to the present invention configured as above will be explained.

The membraneless electrolytic cell 1 is constructed as described above.

Since the same negative voltage as the cathode 5 is applied to the container 4, the chromium alloy does not dissolve into the electrolyte.

By using the decomposer 1 in the above configuration 7, the elution of chromium in the electrolytic cell 1, where heavy metals are most likely to be eluted, is completely prevented, and hydrogen isotopes can be concentrated for a long period of time without reducing the concentration efficiency. .

However, as is clear from the graph in Figure 2, the electrolyte is 1
Due to repeated use, heavy metals are eluted from these electrolyte recovery devices over a long period of time, causing I! ! This may cause contamination of the solution or a decrease in concentration efficiency. For this reason, 1! after electrolytic concentration is completed!
If the equipment for recovering the solute from the solution is electrically insulated from other parts and connected to the cathode, the elution of heavy metals can be more reliably prevented.In the above explanation,
As a method of applying a negative voltage, a negative voltage is connected to the cathode, but a negative voltage may be applied from an external source other than the cathode, as is done in normal cathodic protection.

FIG. 3 shows another example of the membraneless electrolytic cell 1 used in the present invention, in which a chromium or chromium alloy container 4 is electrically connected to the top of a cylindrical iron cathode 5. A cylindrical anode 2 whose wetted surface is nickel-plated is inserted below the cathode 5 and attached to the lower end of the cathode 5 through an insulating material 3.

That is, the membraneless electrolytic cell 1 used in the present invention is as follows.

Electrically, as shown in the principle diagram in Figure 4, the WL pole is 2°5.
The other wetted parts (container) 4 are made of chromium or chromium alloy,
In other parts! I electrically insulating part 21t - connected via
Any material that can be diluted by the gas force ζ circulating gas generated in a sealed structure may be used as long as a negative voltage is applied thereto.

Next, examples and comparative side will be shown to illustrate the effects of the present invention.

Using the apparatus shown in Fig. 2, which is equipped with the membraneless electrolytic concentration tank 1 shown in Fig. 1,! Supply and fill about 100 blades of liquid, and 8
Separation of light hydrogen and deuterium isotopes was performed using a gastric flow of 00 to 1500 A.

However, immediately: molar amount of raw material Hp: molar amount of product χF: molar concentration of heavy water in raw material II' (俤) When condensation was performed by connecting the two, even if batch operations were performed many times, α showed a high concentration efficiency of 8.0 to 10.0 over a long period of time.

Next, when the conducting wire 6 was removed and concentration was carried out in the same manner as above, α decreased with the number of batch runs, and finally reached 4.
．． It was 0 to 4.5.

As described above, the hydrogen isotope concentrator by one-gas decomposition of water according to the present invention maintains highly concentrated young trees for a long period of time, making it possible to concentrate heavy water with extremely high efficiency. .

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of an electrolytic concentrator used in the electrolytic concentrator of the present invention, FIG. 2 is a schematic diagram showing the flow of the device, and FIG. 3 is a diagram showing another example of an electrolytic concentrator. The vertical cross-sectional view, Figure 4, is! FIG. 2 is a principle diagram showing electrical connections. 1...Diaphragmless electrolytic cell (IT# concentration tank), 2...
····anode. 3... Insulating material, 4... Container, 5...
... cathode, 6 ... conductor, 11 ... concentrated electrolyte storage tank, 12 ... distillation column, 12a ...
...Condenser, 13...Product tank, 14...
... Electrolyte adjustment tank, 15 ... Separated electrolyte, electrolyte. 16... Raw material heavy water, 17... Condensate system,
18...Recovered heavy water, 19...Electrolyte storage tank, 20...Gas circulation system, 20a...
Drive device, 21... Insulation section. Applicant Power Reactor and Nuclear Fuel Development Corporation Showa Denko Co., Ltd. Figure 3 Figure 4

Claims (1)

[Claims] A part or all of the material of the wetted parts other than the cathode and anode of the ill m decomposition concentration tank is made of chromium or a chromium alloy, and the material of the wetted parts is electrically insulated from other parts. A hydrogen isotope concentrator by electrolysis of water, characterized in that a negative voltage is applied at the same time as the electrolysis of water. (2) The water bl according to claim 1, wherein the negative voltage is applied by electrically connecting with the cathode.
Hydrogen isotope concentrator using electrolysis.