JPH0647256A - Heat diffusion column to be used for separating isotope - Google Patents

Abstract

PURPOSE:To increase a temp. gradient so as to improve the sepn. efficiency of isotope and to decrease electric energy so as to prolong the life of a heating element by using Al having a high radiation rate as a wall material to be constituted as the cold wall of the heat diffusion column. CONSTITUTION:The heat diffusion column for thickening and separating gases contg. the isotope is provided with a reactor 1 which has the outside wall formed of the Al, is capable of gas-tightly accommodating the gases and is long in a vertical direction, the resistance heating element 2 which is disposed perpendicularly to the central part of the reactor 1 and a cooling means 3 which cools the outside wall of the reactor 1. Consequently, the large temp. gradient in the reactor of the heat diffusion column is taken and the sepn. efficiency of the isotope is improved; in addition, the electric energy loading on the heating element at the center of the heat diffusion column is lessened to prolong the life of the heating element. The energy over the entire part of the device is thus saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat diffusion tower used for carrying out isotope separation utilizing heat diffusion, and in particular, by optimizing the material (physical characteristics) of the reaction vessel constituent members of the heat diffusion tower, the thermal efficiency is improved. The present invention relates to a heat diffusion tower capable of improving energy efficiency and achieving energy saving.

[0002]

2. Description of the Related Art Isotope separation using conventional thermal diffusion is carried out by a thermal diffusion tower having a heat ray on its central axis. The outer wall of the heat diffusion tower is covered with a water cooling jacket to prevent temperature rise. In such a heat diffusion tower, when the central heating wire is heated to 600 ° C to 1000 ° C, a large temperature gradient is formed in the radial direction. In this way, when a large temperature gradient is formed in the heat diffusion tower and, for example, (H2 + D2) mixed gas is introduced therein, gas molecules having different masses have different distributions along the temperature gradient, and thus the mass having a relatively large mass. Gas molecules are concentrated on the low temperature side, and gas molecules with a small mass are concentrated on the high temperature side. Further, convection occurs in the heat diffusion tower, the high-temperature gas around the heat wire rises upward, and the low-temperature gas near the water cooling wall descends downward. In this way, a gas enriched with D2 is obtained from the bottom of the thermal diffusion tower, and a gas enriched with H2 is obtained from the top of the thermal diffusion tower.

A conventional vessel wall material for a heat diffusion tower is, for example, SU.
It was made of stainless steel such as S304.316.
Also, platinum installed in the central portion of the length of the heat diffusion tower,
Heat a heating element such as tungsten to about 1000 ° C,
The wall surface of the heat diffusion tower is cooled with cooling water from the outside, and a predetermined temperature gradient is provided in the radial direction of the container of the heat diffusion tower. Here, it was considered that the outer wall surface of the heat diffusion tower was in thermal equilibrium with the cooling water.

Further, the present applicant has previously proposed a heat diffusion tower in which the cold wall is cooled to a temperature lower than room temperature by using a cryogen, and the temperature of the hot wall can be set relatively low (Japanese Patent Application No. 2-5762,2- 420
49). Again, I thought the cold wall was in thermal equilibrium with the cryogen.

[0005]

In the conventional heat diffusion tower, the energy input to the heating element required to have a large temperature gradient is large, and it is complicated to replace the heating element which tends to reach the end of its life due to the calorific value. . The lower the input energy required, the lower the cost and the longer the life of the heating element.

The present invention considers the structure of the heat diffusion tower from a new point of view, the temperature gradient in the heat diffusion tower container can be made large to improve the isotope separation efficiency, and the heating element at the center of the heat diffusion tower can be improved. It is an object of the present invention to provide a heat diffusion tower in which the electrical energy applied to the device is small, the life of the heating element is extended, and the energy of the entire device can be saved.

[0007]

In a thermal diffusion column used for isotope separation of the present invention, a vertically long reactor having an outer wall formed of aluminum and capable of hermetically containing gas, and a reactor A resistance heating element vertically arranged in the center of the reactor and a cooling means for cooling the outer wall of the reactor.

[0008]

[Operation] By using an aluminum material, which has a higher emissivity than that of conventional stainless steel, as the wall material of the heat diffusion tower,
Increase heat dissipation. Since the temperature rise of the wall material can be kept low, less electric energy is applied to the central heating element that forms the temperature gradient, and the amount of liquid nitrogen used to cool the wall material (evaporation amount) is also kept small. To be

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below. FIG. 1 is a diagram showing an embodiment of a thermal diffusion tower used for isotope separation of the present invention. In the configuration of FIG. 1, the reaction vessel 1 of the heat diffusion tower is an airtight tubular vessel made of aluminum. The shape of the reaction vessel 1 is, for example, an inner diameter of about 30 mm and a length of about 92 cm. The reaction container 1 is erected vertically, and the outer wall of the reaction container 1 is covered with a cryogen jacket 3. The cryogen jacket 3 may be made of aluminum as in the reaction vessel 1, but is preferably made of stainless steel having a low thermal conductivity, and forms a jacket for accommodating the cryogen with the outer wall of the reaction vessel 1. The cryogen jacket 3 may be formed of glass or the like when there is no concern about breakage.

As the cryogen, for example, liquid nitrogen, liquid air, liquid hydrogen, freon or other liquid or gas that operates at 0 ° C. or lower is used. That is, the outer wall of the reaction vessel 1 is not cooled with water in order to prevent the temperature from rising above room temperature, but is cooled with a cryogen to cool below room temperature, preferably below 0 ° C.

A cryogen inlet 7 is provided at the lower end of the cryogen jacket 3 and is connected to a cryogen source 6. A freezing agent outlet 8 is provided at the upper end of the freezing agent jacket 3 to form an outlet for the freezing agent heated by the outer wall of the reaction vessel 1. If necessary, if the cryogen outlet 8 is connected to the cryogen source 6 by the cryogen circulation path 11, the cryogen can be circulated and reused. The processing gas containing a plurality of isotopes is introduced and discharged from the processing gas inlet / outlet 10.

In the reaction vessel 1, a heating wire 2 is arranged along the central axis. A weight 5 is connected to the lower end of the heat wire 2, and the heat wire 2 is held in a vertically stretched state by the action of the weight.

The heating wire 2 is a heater which is heated by passing an electric current, and the heating temperature is 200 ° C. in order to suppress the isotope equilibrium reaction when hydrogen isotopes are separated.
The following are preferred. If liquid nitrogen or the like is used as the cryogen, such a low hot wall temperature is possible. The heater material that can raise the temperature to this level can be selected from a wide range such as tungsten and stainless steel. However, as the heat ray 2, palladium, platinum, or their alloys having a remarkable catalytic action is not used. The heating wire 2 is formed of a wire having a radius of 150 μm, for example.

A plurality of spacers 9 are provided in the middle of the heating wire 2 to keep the distance between the heating wire 2 and the inner wall of the reaction vessel 1 uniform. The spacer 9 is designed, for example, in a cross shape so as not to hinder the flow of gas in the reaction vessel 1. The heating wire 2 is connected to the heater electrode 4 and generates heat by resistance heating by passing an electric current between the heating wire 2 and the other electrode (not shown).

Although the case where the cold wall is cooled with a cooling agent has been described, the cold wall may be water-cooled. When the cold wall is at room temperature, the heating wire is heated to a high temperature.

Here, the outer surface temperature characteristic diagram of the reaction container 1 due to the difference in the wall material shown in FIG. 2 will be described. In this Fig. 2, the case of using the conventional stainless steel wall material,
The temperature rise characteristics of the outer surface of the reaction container 1 with time are measured when an aluminum material is used. In both cases, platinum is used as the heating wire 2, which is a heating element,
The energization amount was a constant value, the thickness of the wall material was 2 mm, and the degree of vacuum was 0.01 Torr. That is, the conditions were the same except for the wall material. As a result, even if the temperature of the heating wire 2 which is the central portion of the reaction vessel 1 is kept constant, the temperature rise of the wall material employing the aluminum material of the present invention is higher than that of the conventional stainless steel. It was confirmed that it could be kept extremely low. This is considered to be due to the difference in emissivity between stainless steel and aluminum.

As described above, in the heat diffusion tower in which the aluminum material is used as the wall material of the reaction vessel, the same heat ray source as in the conventional case is used, and the temperature gradient between the heat ray source and the wall material of the reaction vessel is made large. It is possible to improve the isotope separation efficiency. In addition, since the temperature of the wall surface of the reaction vessel does not rise with time, the amount of energy applied to the central heating element is small, and energy can be saved.

Further, when aluminum is used as the wall material of the reaction vessel, when the method of improving the isotope separation efficiency while cooling the wall with liquid nitrogen is used, compared with the case of using conventional stainless steel. As a result, the amount of liquid nitrogen used (evaporation amount) can be reduced.

The reaction vessel does not necessarily have to be entirely made of aluminum. It is considered that the high emissivity of aluminum can be utilized if there is an outer wall surface formed of aluminum.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0021]

According to the heat diffusion tower used for carrying out the isotope separation utilizing heat diffusion according to the present invention, by using a wall material having a high emissivity as the wall material of the heat diffusion tower, The temperature gradient of the isotherm is large and the separation efficiency of isotopes is improved, and the electrical energy applied to the heating element at the center of the heat diffusion tower is small, the life of the heating element is extended, and the energy saving of the entire device can be achieved. A diffusion tower can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a thermal diffusion tower used for performing isotope separation according to an embodiment of the present invention.

FIG. 2 is a graph showing an example of temperature rise characteristics with respect to time of a heat diffusion tower using an aluminum wall material according to an embodiment of the present invention and a heat diffusion tower using a conventional stainless steel wall material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction vessel 2 Heat ray 3 Cryogen jacket 4 Heater electrode 5 Weight 6 Cryogen source 7 Cryogen inlet 8 Cryogen outlet 9 Spacer 10 Processing gas inlet / outlet 11 Cryogen circulation path

Claims (1)

[Claims] 1. A thermal diffusion tower for concentrating / separating a gas containing an isotope, the reaction vessel having an outer wall formed of aluminum and capable of hermetically containing the gas, and a vertically long reaction container. A thermal diffusion tower comprising a resistance heating element vertically arranged in the center of the reaction vessel, and a cooling means for cooling the outer wall of the reactor.