JPS6344433Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an isotope exchange reaction device for bringing water containing hydrogen isotopes into contact with hydrogen gas to react.

When producing heavy water or removing tritium (hydrogen isotope, symbol T) from nuclear reactor cooling water, water and hydrogen gas are brought into contact and an isotope exchange reaction is carried out to remove hydrogen isotopes in water. Concentration may be increased.

In order to carry out the isotope exchange reaction, a packed column, a tray column, etc. are used, and in either case, an expensive catalyst in which platinum is impregnated on a hydrophobic carrier is used.

Using a large amount of such a catalyst is economically disadvantageous because it increases manufacturing costs and processing costs, and there is a need to reduce the amount of catalyst used. For this purpose, it is necessary to increase the isotope exchange reaction rate constant (hereinafter abbreviated as reaction rate constant), but when the reaction rate constant depends on temperature, it is inevitably limited by the durability temperature of the catalyst. For example, the exchange reaction formula between deuterium (hydrogen isotope, symbol D) and light water is as follows.

H ₂ O (liquid) H ₂ O (air) …(a) H ₂ O (air) + HD (air) HDO (air) + H ₂ (air) …(b) HDO (air) HDO (liquid) …(c ) In this case, the rate-limiting reactions are formulas (a) and (c), but these reaction rates are a function of temperature, and as mentioned above, the reaction rate cannot be sufficiently increased due to the restriction of the catalyst's durability temperature. I couldn't do it.

The present invention was developed in view of the above-mentioned circumstances, and increases the reaction rate constant by adding a device that quickly performs a reaction (hereinafter abbreviated as vapor exchange reaction) in which water vapor accompanying a gas is exchanged with water vapor. The object of the present invention is to provide an apparatus in which the amount of catalyst used is reduced.

Hereinafter, the present invention will be explained based on the illustrated embodiments.

In FIG. 1, the top of the reaction column 1 is provided with a water inlet 2 and a gas outlet 3, while the bottom is provided with a gas inlet 4 and a water outlet 5 as shown.

The reaction tower 1 is provided with a heat exchanger 6 for heat retention,
It is provided with an inlet 7 and an outlet 8 for hot water. A partition plate 9 is provided at a predetermined position in the reaction tower 1, and catalyst layers 10 are formed vertically apart from each other. A vapor exchange device 11 is provided between adjacent catalyst layers 10, respectively.

FIG. 2 shows a detailed system of the steam exchange device 11, in which a gas outlet conduit 12 and a water inlet conduit 13 connected to the lower part of the upper catalyst layer 10 are connected to the humidifier 1.
I am contacting 4. The humidifier 14 is provided with a heater 15 and a branch pipe 16 through which hot water flows. A gas inlet conduit 17 and a water outlet conduit 18 that open above the lower catalyst layer 10 communicate with the lower part of a moisture condenser 19 through which cold water flows (not shown). A gas conduit 2 extending from the top of the condenser 19
0 opens into the humidifier 14, a heater 21 is attached to the water outlet conduit 18, and the branch pipe 16 branches off from the water outlet conduit 18 and opens inside the humidifier 14. ing.

In the embodiment with the above configuration, the inside of the reaction tower 1 is maintained within a predetermined temperature range by the heat exchanger 6. Water is introduced into the reaction tower 1 from the inlet 2 at the top, descends, and then repeatedly reacts with hydrogen gas, which will be described later, in the catalyst layer 10. Hydrogen gas introduced into the reaction tower 1 through the bottom inlet 4 rises and undergoes a predetermined reaction with the descending water.

To further explain the movement of gas, inlet 4
Hydrogen gas (including isotopes) introduced from 4
It enters the catalyst layer 10 of the stage (counting from the top), comes into contact with water descending from above, and an isotope exchange reaction is carried out by the action of the catalyst. Water vapor [HDO
Hydrogen gas containing relatively large amounts of (gas) and HTO (gas) enters the condenser 19 from the gas inlet conduit 17 of the third-stage steam exchanger 11, where the water vapor becomes condensed water and becomes water vapor. Reaction column 1 through outlet conduit 18
The liquid is returned to the inside and dripped onto the fourth stage catalyst layer 10. At this time, since the temperature of the condensed water is lower than that of the reaction tower 1, the temperature of the condensed water is raised to a predetermined temperature by the heater 21.

Water [HDO
(liquid), containing a relatively small amount of HTO (liquid)] enters the humidifier 14 from the water inlet conduit 13 of the third stage steam exchanger 11 and accumulates therein.

In the condenser 19, water vapor [HDO (gas), HTO
The hydrogen gas, which contains a relatively large amount of (air)] has been removed and has become low temperature, enters the humidifier 14 through the gas pipe 20, where it is heated to a predetermined temperature by the heater 15, and the hydrogen gas is heated to a predetermined temperature by the heater 15. (air),
Contains a relatively small amount of HTO (gas)] becomes saturated and enters the third stage catalyst layer 10 from the gas outlet conduit 12, where it descends (water [HDO (liquid), HTO (liquid)]
containing a relatively small amount], an isotope exchange reaction takes place.

In the end, the hydrogen gas released from the fourth stage catalyst layer 10 is
Steam entrained in the moisture condenser 19 in the steam exchanger 11 [contains relatively large amounts of HDO (air) and HTO (air)]
is condensed and removed, and the humidifier 14 applies water vapor [containing comparatively small amounts of HDO (air) and HTO (air)] from the upper stage, thereby exchanging the vapor components to the upper stage (3 stages). 2) enters the catalyst layer 10 of the second layer.

The above-mentioned action is also performed on the first and second stage steam exchangers 11 and catalyst beds 10, and the isotope concentration of the hydrogen gas exiting from the top outlet 3 is lower than when it enters, and the isotope concentration of the hydrogen gas exiting from the bottom exit 5 The isotopic concentration of the water leaving the tank is higher than that of the water going in.

In general, the vapor exchange reaction is slower than the isotope exchange reaction, so the isotope concentration in water vapor [HDO (gas) concentration or HTO (gas) As shown in the figure, there is a large difference between the concentration] and that in water shown by curve 1 at the top of the reaction column 1. However, according to the embodiment of the present invention described above, vapor exchange is forcibly performed between the catalyst layers 10 by the vapor exchange device 11. In this case, the isotope concentration in the water vapor at the top of the reaction tower 1 approaches that in water shown by curve 1 (that is, a large amount of isotope in the water vapor introduced from the bottom of the reaction tower 1 is transferred into water), As a result, in Figure 3, the isotope concentration in water vapor shown by curve 2 and the isotope concentration in hydrogen gas [HD (gas) concentration or HT (gas) concentration] shown by curve 4
and the driving force of the isotope exchange reaction becomes large [for example, the equation
(b) moves to the right], and the isotope exchange reaction between water vapor and gas is promoted. Overall, the reaction rate constant appears to be larger, and the amount of catalyst used can be reduced.

In addition, the catalyst layer was made into a single layer with a thickness of 0.2 m, and the catalyst layer was made into two layers, each with a thickness of 0.1 m.
A comparative test was conducted between this and the steam exchange method described above. When the reaction conditions other than those mentioned above were kept the same, it was found that the reaction rate constant of the latter was about 1.5 times that of the former at a temperature of 40°C, as shown in FIG. Figure 4 shows an Arrhenius plot of the relationship between temperature [1/T (〓 ¹ )] and reaction rate constant [mol/m ³ hr], and curve 5 shows the relationship between temperature [1/T (〓 1 )] and reaction rate constant [mol/m 3 hr]. Curve 51 shows the case of the lower catalyst layer of the present invention, curve 52 shows the case of the upper catalyst layer, and curve 6 shows the conventional case where the catalyst layer is a single layer and no vapor exchange is performed. .

As described above, according to this example, by performing steam exchange, the amount of expensive catalyst used can be reduced, while on the other hand, if the amount of catalyst used is not changed, the efficiency of the isotope exchange reaction can be improved. Alternatively, the reaction temperature can be lowered to increase the lifetime of the catalyst.

Although the embodiments have been described above, the present invention is not limited to the embodiments described above, and as shown in FIG. Warm section (a section that heats condensed water to the temperature of reaction tower 1, filled with a hydrophilic substance, etc.), low temperature section (a water condensation section, filled with a hydrophilic substance, etc.), and evaporation section (A part that imparts water vapor from the water from above to the drying gas and is filled with a hydrophilic substance, etc.) may be formed and configured to perform a vapor exchange action. As shown in Figure B, the evaporator section (which is a section that adds water vapor from the water from above to the dry gas and is filled with a hydrophilic substance, etc.) is placed inside the reaction column 1, and the moisture condenser 19 is placed outside the reaction column 1. Of course, it is also possible to configure them so that they perform the same function.
Many modifications can be made by those skilled in the art based on the idea of the present invention. In addition, Fig. 5 A, B
Inside, the same reference numerals as in FIGS. 1 and 2 indicate the same parts as in FIGS. 1 and 2, 6' is a heat exchanger for cold storage, and 9' is a perforated plate.

[Brief explanation of the drawing]

FIG. 1 is a schematic overall diagram showing an embodiment of the present invention;
FIG. 2 is a diagram showing the details of the steam exchange device according to the embodiment of the present invention, and FIGS. 3 and 4 are graphs showing the effects of the present invention.
Graph showing the relationship between water vapor and isotope concentration in water, Figure 4 is a graph showing the relationship between temperature [1/T (〓 ^-1 )] and reaction rate constant [mol/m ³ · hr], Figure 5
Figures A and B are views showing parts of a steam exchanger according to another embodiment of the present invention. 1...Reaction tower, 2...Water inlet, 3...Gas outlet, 4...Gas inlet, 5...Water outlet, 6...
... Heat exchanger, 10 ... Catalyst layer, 11 ... Steam exchange device, 12 ... Gas outlet conduit, 13 ... Water inlet conduit, 14 ... Humidifier, 15 ... Heater, 16 ...
...Branch pipe, 17...Gas inlet pipe, 18...Water outlet pipe, 19...Condenser, 20...Gas pipe, 21
……heater.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A reaction tower having a water inlet hole and a gas outlet hole at the top, and a water outlet hole and a gas inlet hole at the bottom, separated vertically. In both cases, two stages of catalyst layers are formed, and between the catalyst layers, the water vapor accompanying the rising gas is condensed and the condensed water flows downward, and the dry gas is brought into contact with the water flowing down from above to impart water vapor. 1. A hydrogen isotope exchange reaction device comprising a vapor exchange device having: (2) The steam exchange device includes a humidifier having a gas outlet conduit and a water inlet conduit connected to the lower part of the upper catalyst layer, a branch pipe, and a heater, and a humidifier connected to the humidifier by the gas conduit above the lower catalyst layer. The utility model registration claim (1) comprises a moisture condenser having a gas inlet conduit and a water outlet conduit connected to each other, and a branch pipe of the humidifier and a water outlet conduit of the condenser are connected. Hydrogen isotope exchange reactor.