JPH0442800Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an insulating device, and particularly to the structure of an insulated standpipe that is effective when implemented in a high-temperature gas furnace.

A high-temperature gas furnace is an example of a high-temperature container that stores high-temperature gas therein or heats the gas received therein to a high temperature. High-temperature gas reactors can reach temperatures above 800°C that cannot be obtained with other nuclear reactors, so it is expected that the heat generated will be used for many purposes other than power plants, including nuclear steel manufacturing. On the other hand, high-temperature gas reactors extract heat generated within the reactor at high temperatures, so in addition to measures such as preventing melting of fuel and preventing deterioration of coolant properties, insulation between the reactor and the outside is an extremely important issue. It is.

FIG. 5 shows an overall partially cutaway view of an example of this high-temperature gas furnace. FIG. 1 shows the upper structure of the high temperature gas furnace shown as section A in FIG. In the figure,
Reference numeral 1 is a cylindrical body called a standpipe,
One end is connected to the upper mirror 2 of the reactor pressure vessel.
The other side is inserted through the pressure vessel heat insulating material 8 and connected to the primary shield 5.
placed within. Another shield 6 is formed and arranged inside the standpipe 1, and an orifice drive device 3 for regulating the flow rate of the coolant and a device 4 for driving the control rod are arranged through this shield 6. be. In the figure, reference numeral 9 is a control rod guide tube, and 7 is a guide tube 9.
This is a support plate that supports. In other words, in the current structure of the standpipe 1, there is a space between the support plate 7 and the shield 6, and there is a risk that a considerable amount of heat from the reactor side will be transferred to the equipment side such as the orifice drive device 3. be.

Figure 2 shows an outline of the heat transfer state, in which ventilation air A at about 40°C flows down into the space formed between the outer periphery of the standpipe 1 and the primary shield 5. Standpipe 1 is being cooled.
On the other hand, the space below the pressure vessel heat insulating material 8 is heated to about 400° C. by heat generated from the nuclear reactor. Therefore, a convection phenomenon occurs in the standpipe 1 as shown by arrow B, and a considerable amount of heat is transferred to the shield 6 side. For this reason, the temperature of the space in which the orifice drive device 3 and the control rod drive device 4 are arranged also ranges from 80 to 80°C.
Temperatures can rise to around 100℃. Here, it is necessary to keep the temperature of the parts where these various devices are arranged low, and usually it is necessary to keep it at about 60°C or less in order for the devices to operate normally. Therefore, as mentioned above, the temperature is 80
If the temperature rises above ℃, there is a risk of equipment malfunction or failure, and insulation of the space below the standpipe is required.

As a method of insulating the standpipe, it is possible to use fiber-based insulation materials such as ceramic fiber, but these insulation materials have a porosity of 90% even when compressed.
% or more, the heat transfer coefficient is not much different from that of the helium gas occupying this space, and the heat insulation effect is poor.
There is also a risk that dust may be mixed into the primary coolant due to powdering of the heat insulating material.

The purpose of this invention is to provide a heat insulating device that can eliminate the above-mentioned problems and effectively prevent a rise in temperature within the standpipe.

In short, this idea is based on the stand pipe of a high temperature gas reactor that has a control rod guide tube inside.
A plurality of shielding plates are installed horizontally inside the standpipe to cross its axis, and the intervals between these shielding plates are set close in areas of the standpipe where the temperature gradient is large, and in areas where the temperature gradient is small. This is characterized by an insulated standpipe for a high-temperature gas furnace whose spacing is coarse.

Examples of this invention will be described below with reference to the drawings.

In FIG. 3, for the lower space of the standpipe 1 between the shielding body 6 and the support plate 7, a metal plate 1, which is a shielding plate made of stainless steel, etc.
1 are arranged horizontally in multiple stages with a certain space between them. The metal plate 11 may be installed directly in the lower space, or may be installed in a case 10 formed and arranged in the lower space, and the metal plate 11 and the case 10 may be made into a unit.

Next, the setting of the distance between each metal plate will be explained.

Here, suppose that two flat plates are placed in parallel, one for heating at the bottom and one for cooling at the top.
It has been confirmed that natural convection does not occur if Gr・Pr<1700. Here, Gr represents the Grafhoff number, and the Grafhoff number has the relationship shown in the following equation.

Gr=S ³ gβ (T ₁ − T ₂ )/r ² Pr: Prandtl index S: Distance between plates g: Power acceleration β: Coefficient of thermal expansion of fluid T ₁ : Temperature of lower plate T ₂ : Temperature of upper plate r: Kinematic viscosity coefficient of fluid Based on the conditions shown above, if S≒20 mm, natural convection can be prevented. Also flat plate (metal plate)
A thin plate with a thickness of about 0.1 mm is sufficient. code 12
is a breathing hole, which allows gas inside the case 10 to escape and prevents external pressure from being applied by the primary coolant.

FIG. 4 shows another embodiment. stand pipe 1
In this case, the temperature gradient in the standpipe axial direction is large near the pressure vessel heat insulating material 8, and is relatively small in other parts. In other words, the amount of heat transfer is particularly large in areas with large temperature gradients, so the arrangement density of metal plates in these areas is increased and the arrangement density in other areas is reduced, and the metal plates are arranged without reducing the overall insulation capacity. It is configured to reduce the number of sheets.

By implementing this invention, the heat insulation of the space below the standpipe can be greatly improved, so that equipment placed inside the standpipe will not be affected by heat.

Furthermore, unlike fiber-based heat insulating materials, there is no problem such as pulverization of the fibers, so there is no risk of dust getting mixed into the gas, which is the primary coolant.

Furthermore, it is simpler and lighter in weight than ordinary insulation structures.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a standpipe of a conventional high-temperature gas furnace, Figure 2 is a schematic diagram showing the state of convection in the standpipe, and Figure 3 is a cross-section of a standpipe equipped with the heat insulation device according to this invention. FIG. 4 is a sectional view of a stand pipe showing another embodiment, and FIG. 5 is a partially cutaway perspective view of a high temperature gas furnace. 1...stand pipe, 2...upper mirror, 11...
Shield.

Claims (1)

[Scope of utility model registration request] In a standpipe for a high-temperature gas reactor that has a control rod guide tube inside, a plurality of shielding plates are horizontally provided inside the standpipe to cross its axis, and the intervals between these shielding plates are determined by the temperature of the standpipe. An insulated standpipe for a high-temperature gas furnace, characterized in that the intervals are close in parts where the temperature gradient is large, and the intervals are coarse in parts where the temperature gradient is small.