JPH0547965Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a steam generator for obtaining steam from heat generated in a fast breeder reactor.

Prior Art A power generation system using a fast breeder reactor is schematically shown in Fig. 4, in which a primary coolant is provided between a reactor vessel 2 containing a reactor core 1 and an intermediate heat exchanger 3. A certain liquid sodium 4 is circulated, liquid sodium 6 which is a secondary coolant is circulated between the intermediate heat exchanger 3 and the steam generator 5, and water is further circulated in the steam generator 5. 7 is supplied, water 7 is heated by the heat possessed by liquid sodium 6, which is a secondary coolant, and becomes superheated steam.The heated steam is sent to a turbine 8 and is condensed in a condenser 9 installed after the turbine 8. This applies back pressure to drive the turbine 8, and the turbine 8 rotates the generator 10 to generate electricity.

However, with the above-mentioned configuration, since the intermediate heat exchanger 3 is provided, the radioactively contaminated liquid sodium 4, which is the primary coolant, comes into direct contact with the water 7, and as a result, explodes and leaks to the outside. Although leakage is effectively prevented, since the intermediate heat exchanger 3 itself is a fairly large piece of equipment, there is a problem in that the whole piece of equipment has to be enormous. In addition, the steam generator 5 is configured to exchange heat between liquid sodium 6 and water 7, which are secondary coolants, with one partition wall in between, so the liquid may There was a risk that sodium 6 and water 7 would come into contact and cause an explosive reaction.

In order to solve this inconvenience, conventionally,
Attempts have been made to perform heat exchange between liquid sodium and water via heat pipes. Examples thereof are schematically shown in FIGS. 5 and 6. That is, inside the main body container 12 of the steam generator 11, a large number of double-tube structure heat pipes 13 are arranged vertically. The heat pipe 13 is partitioned into a header portion 15 and an intermediate portion 16 therebetween, and an inner pipe 17 passing through the center of the heat pipe 13 communicates with each of the header portions 14 and 15. And main container 1
An inlet 18 is formed in the upper part of the middle part of the 2, and an outlet 19 is formed in the lower part.
It is connected to the reactor vessel 21 so as to circulate and supply liquid sodium 20 as a secondary coolant. Therefore, in the heat pipe 13, the working fluid 22 is evaporated by receiving heat from the liquid sodium 20 on the outer circumferential side, and by letting the water 23 flow through the inner pipe 17, the steam of the working fluid 22 is converted to water 2.
3 and converts it into superheated steam, so that the heat pipe 13 generates liquid sodium 20 and water 2.
Mediates heat exchange between 3 and 3. Also, the working fluid 22
By using a substance that does not react with sodium and water, such as mercury, explosive reactions due to leaks due to pinholes, cracks, etc. are prevented.

Problems to be Solved by the Invention However, since the above heat pipe type steam generator has a configuration in which the high temperature liquid sodium 20 flows from the upper side to the lower side, the temperature of the water or steam, the temperature of the heat pipe, and the temperature of the liquid sodium are Each temperature distribution is as shown in FIG. In other words, the temperature of the liquid sodium is high in the upper part, and most of the working fluid 22 in the heat pipe accumulates in the lower part, so there is a shortage of liquid phase working fluid in the upper part of the heat pipe, and the temperature becomes extremely high. . This is because so-called dryout occurs at the top of the heat pipe, and only heat is input and no heat is given to the water. This is the same situation as the effective length of . As described above, in the conventional steam generator described above, the heat pipe does not function effectively, resulting in a problem of poor heat exchange efficiency.

This invention was made against the background of the above-mentioned circumstances, and the purpose is to provide a steam generator for a fast breeder reactor with good heat exchange efficiency.

Means for Solving the Problems In order to achieve the above object, this invention provides a heat pipe around the outer periphery of the flow pipe through which the first heat medium flows, and a second heat pipe on the outer periphery of the heat pipe. A flow section for flowing a heat medium is provided, and the heat pipe is installed so that its axis is directed in the vertical direction, and further, one of the first and second heat medium is water or steam, and the other is a reactor vessel. In a steam generator for a fast breeder reactor, which is a high-temperature coolant supplied from It is characterized by the fact that

Function Therefore, also in the steam generator of this invention,
A heat pipe is interposed between the high-temperature coolant supplied from the reactor vessel and water or steam, and the heat of the coolant is imparted to the water or steam through the heat pipe. Therefore, even when the coolant is liquid sodium, the coolant is prevented from coming into direct contact with water and reacting explosively. Since the high-temperature coolant flows from the bottom to the top of the heat pipe, the heat flux is large at the bottom end where there is a lot of working fluid, and the heat flux is small at the top end where there is less working fluid. , the heat flux is proportional to the amount of working fluid, so there is good heat transport over the entire length of the heat pipe without partial dryout, and heat transfer between the coolant and water or steam is achieved. Good exchange efficiency.

Embodiment Next, an embodiment of this invention will be described with reference to the drawings.

FIGS. 1 and 2 are schematic diagrams showing the principle of an embodiment of this invention, and the inside of the main body container 12 of the steam generator 11 includes an upper header part 14, a lower header part 15, and a space between them. and a middle part 16, and in the middle part 16, a large number of heat pipes 13 having a double pipe structure are arranged in parallel to each other with their axes directed in the vertical direction. The structure of the heat pipe 13 is as shown in FIG. 2, in which an inner tube 17 penetrates along the central axis, the upper end of the inner tube 17 communicates with the upper header section 14, and the lower end is in communication with the lower header portion 15 , and the intermediate portion of the heat pipe 13 is located within an intermediate portion 16 defined within the main body container 12 . Note that as the working fluid 22 of the heat pipe 13, a condensable fluid such as mercury that does not react with either sodium or water is used. An outflow port 19 is formed in the main body container 12 at a position corresponding to the upper end of the intermediate portion 16, and an inflow port 18 is formed at a position corresponding to the lower end. A coolant supply pipe 24 is connected to supply liquid sodium 20 from the reactor vessel 21 to the outlet 19, and a coolant supply pipe 24 is connected to the outlet 19 to supply liquid sodium 20 with a reduced temperature to the reactor vessel 21.
A coolant reflux pipe 25 is connected thereto.

In the steam generator 11 configured as described above, water 23 is supplied to the lower header section 15 and flows from the bottom to the top inside the inner tube 17, and the high temperature liquid sent out from the reactor vessel 21 sodium 20
is supplied to the main vessel 12 from the inlet 18, flows downward or upward through the intermediate portion 16, and then is returned to the reactor vessel 21 from the outlet 19.
Therefore, the outer circumferential side of the heat pipe 13 becomes high temperature and the inner circumferential side becomes low temperature, and heat exchange occurs therebetween. That is, the working fluid 22 in the heat pipe 13 is heated by the heat of the liquid sodium 20 and evaporates, and the vapor comes into contact with the inner tube 17, where the water or steam flowing inside the tube absorbs the heat and condenses. As a result, the working fluid 22 transports heat as its latent heat from the outer circumferential side to the inner circumferential side, mediating heat exchange between the liquid sodium 20 and the water 23.

In that case, in the steam generator 11 described above, high-temperature liquid sodium 20 is supplied from the lower side of the intermediate section 16 and flows upward, and during that time the heat of the liquid sodium 20 is given to the water 23. As shown in FIG. 3, the temperature of the sodium 20 is high at the lower end of the intermediate portion 16 and gradually decreases at the upper end. On the other hand, the working fluid 22 within the heat pipe 13 is unevenly distributed toward the lower end due to the influence of gravity.
That is, since the working fluid 22 is distributed in accordance with the amount of heat flux from the liquid sodium 20, good heat transport occurs over the entire length of the heat pipe 13. Therefore, the temperature distribution of the water 23, the heat pipe 13, and the liquid sodium 20 in the main container 12 becomes as shown in FIG. 3, and as can be seen from this figure, there is a partial dryout in the heat pipe 13. Does not occur.

The liquid sodium 20 which has released heat as described above flows back into the reactor vessel 21 and is heated and heated, and then supplied to the main body vessel 12 again. Further, water heated while flowing inside the inner pipe 17 becomes superheated steam and is sent out from the upper header section 14 to a turbine (not shown) or the like.

In the above embodiment, high temperature liquid sodium 20 is flowed around the outer circumferential side of the heat pipe 13, and the inner pipe 1
However, in this invention, contrary to the above embodiment, high-temperature liquid sodium is supplied from the bottom of the inner tube, and water or steam is supplied to the outer periphery of the heat pipe. You can also let it flow to the side.

Effects of the invention As is clear from the above explanation, according to the steam generator for a fast breeder reactor of this invention, the heat flux from the outside corresponds to the uneven distribution of the working fluid in the heat pipe. As a result, good heat transport occurs over the entire length of the heat pipe, resulting in efficient heat exchange.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the principle of the overall configuration of this device, Figure 2 is a schematic diagram showing one of the heat pipes, and Figure 3 is a diagram showing water and liquid sodium in the axial direction of the heat pipe. and a diagram showing the temperature distribution of the heat pipe, and Figure 4 is a schematic diagram for explaining a power generation system using a fast breeder reactor.
Figure 5 is a schematic diagram showing the general structure of a conventional heat pipe steam generator in principle, Figure 6 is a schematic diagram showing one of the heat pipes, and Figure 7 is the axial direction of the heat pipe. FIG. 2 is a diagram showing the temperature distribution of water, liquid sodium, and a heat pipe at . 11...Steam generator, 12...Main container, 13
... Heat pipe, 16 ... Middle part, 17 ... Inner pipe, 18 ... Inlet, 19 ... Outlet, 20 ...
Liquid sodium, 21... Reactor vessel, 22...
Working fluid, 23...water.

Claims (1)

[Claims for Utility Model Registration] A heat pipe is provided on the outer periphery of the flow pipe through which the first heat medium flows, and a flow section through which the second heat medium flows is provided on the outer peripheral side of the heat pipe, and A fast breeding method in which the pipe is installed so that its axis faces vertically, and one of the first and second heat carriers is water or steam, and the other is a high-temperature coolant supplied from the reactor vessel. A steam generator for a fast breeder reactor, characterized in that a coolant inlet and an outlet are formed in the flow pipe or the flow section so that the coolant flows from the bottom to the top. steam generator.