JPH02223391A - Thermoelectric generator - Google Patents

Abstract

PURPOSE:To obtain a simplified static thermoelectric generator which can be maintained and inspected easily by converting heat directly into electricity thereby eliminating steam generator, turbine, generator and the like. CONSTITUTION:High temperature fluid, i.e., high temperature molten sodium, heated to about 500 deg.C through a nuclear reactor 2 is fed continuously to a thermoelectric generator 3 where it heats the high temperature side of the thermoelectric generator 3 and the temperature of the molten sodium drops to about 400 deg.C, then the molten sodium is returned through an electromagnetic pump 6 and a molten sodium discharge line 5 to the nuclear reactor 2. On the other hand, low temperature fluid, i.e., sea water having temperature of about 25 deg.C, is fed through a cooling water supply line 7 and cools the low temperature side of the thermoelectric generator 3 then it is discharged through a cooling water discharge line 8 with its temperature being lowered to about 32 deg.C. By such arrangement, electromotive force is produced in the thermoelectric element of the thermoelectric generator 3, then the DC power is inverted through an inverter 9 into AC power which is transmitted on a transmission line 10 to consumers.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a thermoelectric power generation device, and more specifically, to a device that directly converts thermal energy into electrical energy without using a turbine or a generator. be.

[Conventional technology]

A conventional nuclear power generation facility that converts thermal energy into electrical energy has a configuration as shown in FIG. 11, for example.

In FIG. 11, 51 is a reactor containment vessel, 52 is a nuclear reactor, 53 is a primary system high temperature molten sodium line, 54 is an intermediate heat exchanger, 55 is a secondary system high temperature molten sodium line,
56 is a high temperature and high pressure steam generator, 57 is a steam line, 58
59 is a steam turbine, 59 is an alternator, and 60 is a power transmission line.

That is, the primary system high-temperature molten sodium heated in the reactor 52 exchanges heat with the secondary system high-temperature molten sodium in the intermediate heat exchanger 54, and this heat-exchanged secondary system high-temperature sodium is exchanged with water in the steam generator 56. Heat to generate steam. This steam is supplied to a steam turbine 58, which rotates to rotationally drive an alternating current generator 59, which generates alternating current power, which is supplied to the utility light from a power transmission line 60.

[Problem to be solved by the invention]

As mentioned above, the conventional technology for converting thermal energy into electrical energy requires an intermediate heat exchanger 54, a steam generator 56, a steam turbine 58, a generator 59, etc. There is a problem in that it requires equipment and a lot of piping associated with it, and it costs a lot of money to maintain and inspect them, making it uneconomical.

There are also problems with mechanical loss and noise caused by moving parts.

The present invention attempts to solve these problems. That is, the present invention directly converts heat into electricity, thereby eliminating the need for steam generators, turbines, generators, etc., making it static and simple, and making maintenance and inspection easier. The object of the present invention is to provide a thermoelectric power generation device that can significantly improve safety and reliability.

[Means for Solving the Problems] In order to achieve the above object, the thermoelectric power generation device of the present invention has the following features:
A P-type amorphous semiconductor thermoelectric material and an N-type amorphous semiconductor thermoelectric material are paired and formed into a sandwich shape with a material that is a poor conductor both electrically and thermally in between, and is also formed into a donut shape. , a large number of thermoelectric elements whose inner and outer circumferential parts are on the high temperature side and the other on the low temperature side are connected through a device that is a poor conductor both electrically and thermally. A stacked hollow cylindrical thermoelectric element assembly, an inner tube that is a heat conductor located in the hollow part at the center of the thermoelectric element assembly, and a heat conductor located outside the thermoelectric element assembly. The thermoelectric generator includes an outer tube that is a conductor, and each P-type amorphous semiconductor thermoelectric material and each N-type amorphous semiconductor thermoelectric material of the thermoelectric element of the thermoelectric element assembly are arranged alternately on a high temperature side and a low temperature side. are electrically connected in order and connected in series as a whole, and have flow paths through which high-temperature fluid and low-temperature fluid flow separately, and the high-temperature fluid applies heat to the high-temperature side of the thermoelectric element. The low-temperature fluid removes heat from the low-temperature side of the thermoelectric element.

[For production]

According to the present invention, the high-temperature fluid and the low-temperature fluid are continuously flowed through separate wave paths, and the high-temperature fluid heats the high-temperature side of the thermoelectric element, and at the same time, the low-temperature fluid cools the low-temperature side of the thermoelectric element. , an electromotive force is generated in each thermoelectric element. Furthermore, since the thermoelectric elements are electrically connected in series, a relatively large DC power can be obtained as the sum of their electromotive forces.

〔Example〕

FIG. 1 shows a first embodiment of the invention.

In Figure 1, 1 is the reactor containment vessel, 2 is the reactor, and 3 is the reactor containment vessel.
4 is a molten sodium supply line, 5 is a molten sodium discharge line, 6 is an electromagnetic pump,
7 is a cooling water supply line, 8 is a cooling water discharge line, 9 is a converter that converts direct current to alternating current, and 10 is a power transmission line.

That is, high-temperature molten sodium as a high-temperature fluid heated to about 500'C in the reactor 2 is continuously supplied to the thermoelectric generator 3, and heats the high-temperature side of the thermoelectric generator 3, which will be described later, to about 400°C. C and is returned to the reactor 2 from the molten sodium discharge line 5 by the electromagnetic pump 6. On the other hand, cooling water of about 25℃ such as seawater as a low-temperature fluid,
The cooling water flows in from the cooling water supply line 7 and cools the low-temperature side of the thermoelectric generator 3, which will be described later, to a temperature of about 32° C. and is discharged from the cooling water discharge line 8.

As a result, an electromotive force is generated in the thermoelectric element of the thermoelectric generator 23, and the DC power is converted into AC power by the converter 9 and transmitted from the power transmission line IO to the utility light.

FIG. 2 is an explanatory diagram of the principle of thermoelectric power generation using the semiconductor of the thermoelectric power generation device 3, in which 11 is a P-type amorphous semiconductor thermoelectric material, 12 is an N-type amorphous semiconductor thermoelectric material, 13 is an electrical insulator, and 14 is a hole ( +), 15 is electron (-), 16
16a is a conductor on the high temperature side, 16b and 16c are electric conductors on the low temperature side, and 17 is a light bulb.

The principle of this thermoelectric power generation is similar to the known thermocouple for temperature measurement.The thermoelectric materials 11 and 12 are heated on the low temperature side due to the temperature difference between the high temperature side and the low temperature side of the thermoelectric materials 11 and 12.
, 12, and when a light bulb 17 is connected to this electromotive force, it lights up.

This thermoelectric power generation efficiency approaches the ideal efficiency (Carnot efficiency) as the figure of merit Z increases, and the efficiency increases as the temperature difference increases.

Here, the figure of merit Z is expressed by the following formula.

However, from the above equation (1), it is desirable that the thermoelectric element has a large Seebeck coefficient, conducts electricity well, and does not conduct heat.

Table 1 shows the performance index of the main materials.

FIG. 3 shows the relationship between the thermal efficiency η of thermoelectric power generation and the figure of merit Z.

From Table 1 and FIG. 3 above, it is clear that amorphous FeS i 2
has a figure of merit Z of 10-! Moreover, since the raw material is cheap, the above-mentioned Fe is used as an amorphous semiconductor thermoelectric material.
5i= is desirable.

FIG. 4 is a partially cutaway front sectional view showing the thermoelectric power generation device 3 of FIG. 1.

In Fig. 4, 18 is a cylindrical outer shell, 19 is a main pipe plate,
20 is an auxiliary tube plate, 21 is a thermoelectric generator to be described later, 22 is a sodium inlet to which the molten sodium supply line 4 shown in FIG. 25 is a cooling water inlet that connects the cooling water supply line 7, 25 is a cooling water outlet that also connects the cooling water discharge line 8, and 26 is an obstruction for making the upward flow of cooling water in the outer shell 18 into a meandering shape. A plate 27 is provided between the main tube plate 19 and the auxiliary tube plate 20 and is filled with helium (
This is an inert gas inlet for sealing inert gas such as He) or nitrogen (N2).

A large number of thermoelectric generators 21 are installed upright, and each thermoelectric generator 21 is electrically connected in parallel.

FIG. 5 is an enlarged front sectional view of the thermoelectric generator 21 shown in FIG. 4, with a portion cut away.

The thermoelectric generator 21 includes a hollow cylindrical thermoelectric element assembly 28, and an inner tube located in the central hollow part of the thermoelectric element assembly 28, through which high-temperature molten sodium flows to supply heat to the high-temperature side of the thermoelectric element, which will be described later. 29, and an outer tube 30 that is located outside the thermoelectric element assembly 28 and is provided so as to be in circumscribed contact with the cooling water that removes heat from the low temperature side of the thermoelectric element.

Then, the thermoelectric element assembly 2nd is made of P-type amorphous Fe.
5it semiconductor thermoelectric material 31 and N-type amorphous FeSi
, a pair of semiconductor thermoelectric materials 32 are formed in a sandwich shape with an insulator 33, which is a poor conductor both electrically and thermally, sandwiched therebetween, and are also formed in a donut shape. A hollow cylindrical element in which a large number of thermoelectric elements 34, each having a high-temperature side and a low-temperature outer peripheral surface, are laminated via an insulator 35, which is a poor conductor both electrically and thermally. It consists of.

Moreover, each P-type amorphous PeSi z semiconductor thermoelectric material 31 and each N-type amorphous Fe5iz semiconductor thermoelectric material 3 and 2 of the thermoelectric element 34 of the thermoelectric element assembly 28'' are electrically conductive alternately on the high temperature side and the low temperature side. 36 and 37, and are connected in series as a whole.

On the second day of the thermoelectric element assembly, the inner circumferential surface of the electrical conductor 36 is
and an inner layer 38 in close contact with the outer peripheral surface of the inner tube 29, and an electrical conductor 3.
The inner layer 38 and the outer layer 39 are made of beryllium oxide or the like, which is a poor conductor electrically and a good conductor thermally. It has become °.

Further, a heat insulating material 40 is provided between the inner tube 29 and the outer tube 30.

In the thermoelectric generator 21 configured as shown in FIG. 5, high-temperature molten sodium flows down the inner tube 29 to heat the high temperature side of each thermoelectric element 34 of the thermoelectric element assembly 28, and at the same time, each thermoelectric element Since the low temperature side of the thermoelectric element 34 is cooled by cooling water, an electromotive force is generated in each thermoelectric element 34 as explained in FIG.
Since they are electrically connected in series, the total DC power of their electromotive forces can be obtained continuously. Furthermore, the space between the inner tube 29 and the outer tube 30 is airtight, and as shown by an arrow 41,
A pressurized inert gas such as He or N2 is filled in, and during operation, the gas pressure is detected and leaks from the inner tube 29 and outer tube 30 are monitored. Even if at least one of the inner tube 29 and outer tube 30 leaks, the gas pressure is made higher than the pressure of high-temperature molten sodium and the water pressure of the cooling water around the outer periphery of the outer tube 30, so that the gas leaks into the inside of the airtight structure. Prevent sodium and water from leaking and prevent sodium and water from reacting.

6 is a partially cutaway front sectional view of a thermoelectric generator 3 showing a second embodiment of the present invention, and FIG. 7 is a partially cutaway front view showing an enlarged view of the thermoelectric generator 21 of FIG. FIG.

The difference between this FIG. 6 and the above-mentioned FIG. 4 is that in the lower part of the outer shell 18, there is only the main tube plate 19, and in the upper part, there is an intermediate tube between the main tube plate 19 and the auxiliary tube plate 20. A plate 42 is provided, and as shown in FIG. 7, the inner tube through which high-temperature molten sodium flows consists of a double tube consisting of an inner thin tube 43 and an outer thin tube 44, which are supported by a support member 45. Then, the high-temperature molten sodium flows downward in the inner thin tube 43 and flows upward in the outer thin tube 44. Therefore, as shown in FIG. 6, the sodium outlet 23 is provided between the main tube plate 19 and the intermediate tube plate 42, and the cooling water outlet 24 is provided relatively upwardly.
This is because the cooling water outlet 25 is provided relatively lower.

In this way, by making the inner tube through which high-temperature molten sodium flows into the inner tube 43 and the outer tube 44, the upper part is an area containing only sodium (Na), the lower part is an area of cooling water, and Na.
Water is separated and the occurrence of Na/water reaction can be prevented.

The rest is the same as the first embodiment shown in FIGS. 4 and 5.

FIG. 8 shows only the thermoelectric element of the third embodiment of the present invention, FIG. 8(a) is a plan view, FIG. 8(b) is a sectional view,
Figure 8 (C) is an explanatory diagram of the temperature gradient of each part, Figure 8 (
d) is an explanatory diagram of the relationship between the figure of merit and temperature.

This is amorphous FeSi, a semiconductor thermoelectric material with different characteristics! , II, and III are multilayered to make effective use of heat.

In FIG. 8, 47 is an insulator that is a poor conductor both electrically and thermally, 48 is a conductor on the high temperature side, 49 is a conductor on the low temperature side, and the temperature at the conductor 49 on the low temperature side is T( 1. The temperature at the conductor 48 on the high temperature side is T1, and the temperature in the middle is Tt.
and T2, respectively, as shown in Figure 8(C), '
The relationship is ro <T, <'rz <T3.

That is, each amorphous Fe5i8 semiconductor thermoelectric material having a temperature-dependent figure of merit suitable for the temperature gradient within the thermoelectric element 46 is molded into an integral structure.

In this way, the energy extracted will be as follows.

The electromotive force is E, the temperature is T, and the respective figures of merit are z, ,Z
,, Zc. Therefore, a much larger electromotive force can be obtained than using one material. A and B in FIG. 8(d).

Possible examples of C include amorphous Fe5iz semiconductor thermoelectric materials made in C, H, and O□ plasma atmospheres, respectively.

FIG. 9 shows a fourth embodiment of the invention.

In this fourth embodiment, the inner periphery of the thermoelectric element of each thermoelectric generator 21 is on the low temperature side and the outer periphery is on the high temperature side, that is, the low temperature side and the high temperature side are exactly as shown in FIG. is reversed, other things are the same. That is, the ninth
In the case shown in the figure, cooling water continuously enters from the cooling water outlet 24, rises inside the inner pipe 29 of the thermoelectric generator 21, and rises to the cooling water outlet 24.
At the same time, hot molten sodium continuously enters from the sodium port 22, flows down along the outer surface of the outer tube of the thermoelectric generator 21, and is discharged from the sodium outlet 23. Even in this case, the same effect as in the case of FIG. 4 can be obtained.

FIG. 10 shows a fifth embodiment of the invention.

In this fifth embodiment, high-temperature helium gas (He) is used as the high-temperature fluid, and the difference from FIG. 9 is as follows.
The outer shell 18 is provided with a gas port 22a and a gas outlet 23a, and a large number of fins 50 are provided on the outer peripheral surface of the thermoelectric generator 21.

In this fifth embodiment, for example, high-temperature helium gas at about 800°C flows in from the gas port 22a, continuously heats the high-temperature side of each thermoelectric generator 21 to lower the temperature to about 400°C, and then the gas exits. It flows out from 23a. At the same time, cooling water at about 25°C flows in from the cooling water port 24 and passes through the inner pipe 29 of each thermoelectric generator 21 to continuously cool the low temperature side of the thermoelectric generator 21 and raise the temperature to about 32°C. The cooling water then flows out from the cooling water outlet 25. Thereby, DC power can be continuously extracted from the cough thermoelectric generator 21.

Note that in Figures 4 to 7 and Figure 9, high-temperature molten sodium (FJa) is used as an example of the high-temperature fluid, and in Figure 10, helium gas (He) is used as an example. ) or argon (Ar),
Nitrogen (Nz>, hydrogen ()It), combustion gas, combustion exhaust gas, etc. may be used. Furthermore, air or the like may be used outside the waterside as the low-temperature fluid.

Furthermore, in FIGS. 4, 6, 9, and 10,
Although the thermoelectric generators 21 are electrically connected in parallel, they may be connected in series or in a combination of series and parallel.

〔Effect of the invention〕

As explained above, according to the present invention, a P-type amorphous semiconductor thermoelectric material and an N-type amorphous semiconductor thermoelectric material are formed in a sandwich shape by sandwiching a pair that is a poor conductor both electrically and thermally. At the same time, many of the thermoelectric elements are shaped like donuts, and one of the inner and outer circumferences is on the high temperature side, and the other side is on the low temperature side. A hollow cylindrical thermoelectric element assembly laminated via materials that are thermally poor conductors, an inner tube that is a heat conductor located in the hollow center of this thermoelectric element assembly, and the thermoelectric element assembly. Since it consists of a thermoelectric generator equipped with an outer tube that is a heat conductor located outside the element assembly, the thermoelectric generator has a cylindrical shape and the necessary components are integrated inside it. It can be made compact and compact. Moreover, the high temperature fluid and the low temperature fluid are provided with flow paths that flow separately, so that the high temperature fluid applies heat to the high temperature side of the thermoelectric element, and the low temperature fluid removes heat from the low temperature side of the thermoelectric element. Therefore, the high temperature side of the thermoelectric element is heated to a required temperature, and the low temperature side of the thermoelectric element is cooled to a required temperature, thereby generating an electromotive force in each thermoelectric element. Therefore, thermal energy can be directly converted into electrical energy without going through a turbine or generator, which eliminates the need for turbines, generators, their auxiliary equipment, long piping, etc., making it static and simple. This makes it possible to significantly reduce equipment costs, facilitate maintenance and inspection, and significantly improve safety and reliability. Furthermore, since the thermoelectric elements are electrically connected in series, a relatively large DC power can be obtained as the sum of the electromotive forces generated in each thermoelectric element.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the first embodiment of the present invention, Fig. 2 is an explanatory diagram of the principle of thermoelectric power generation, Fig. 3 is an explanatory diagram of the relationship between the thermal efficiency of thermoelectric power generation and the figure of merit, and Fig. 4 1 is a partially cutaway front sectional view showing the thermoelectric generator of FIG. 1, FIG. 5 is a partially cutaway front sectional view showing an enlarged thermoelectric generator of FIG. 4, and FIG. FIG. 7 is a partially cutaway front sectional view of the thermoelectric generator shown in the second embodiment, and FIG. 7 is a partially cutaway front sectional view showing an enlarged view of the thermoelectric generator of FIG. ). (C) and (d) are explanatory diagrams showing only the thermoelectric element of the third embodiment of the present invention, FIG. 9 is a partially cutaway front sectional view showing the fourth embodiment of the present invention, and FIG. Similarly, FIG. 11 is a partially cutaway front sectional view showing the fifth embodiment, and is an explanatory view showing an example of the conventional technique. 2... Nuclear reactor, 3... Thermoelectric generator, 4
... Molten sodium supply line, 5... Molten sodium discharge line, 7... Cooling water supply line, 8... Cooling water discharge line, 10... Power transmission line, 21... Thermoelectric generator ,2
2...Sodium inlet, 22a...Gas inlet, 23
...Sodium outlet, 23a...Gas outlet, 24.
・・Cooling water inlet, 25・・Cooling water outlet, 27・
...Inert gas inlet, 28...Thermoelectric element assembly, 29
...Inner pipe, 30...Outer pipe, 31...
P-type amorphous Fe5il semiconductor thermoelectric material, 32...
・N-type amorphous Fe5iz semiconductor thermoelectric material, 33・
・Insulators that are poor conductors both electrically and thermally,
34... Thermoelectric element, 35... Insulator that is a poor conductor both electrically and thermally, 36.37...
Electric conductor, 38... Inner layer, 39... Outer layer, 43... Inner tubule, 44... Outer tubule, 6... Thermoelectric element.

Claims (1)

[Scope of Claims] 1. A P-type amorphous semiconductor thermoelectric material and an N-type amorphous semiconductor thermoelectric material are formed in a sandwich shape, sandwiching a pair of materials that are poor conductors both electrically and thermally. , which is shaped like a donut and has one of its inner and outer peripheries on the high-temperature side and the other on the low-temperature side, electrically and thermally. A hollow cylindrical thermoelectric element assembly laminated with a poor conductor interposed therebetween, an inner tube that is a heat conductor located in a hollow part at the center of the thermoelectric element assembly, and The thermoelectric generator includes an outer tube that is a heat conductor located on the outside, and each P-type amorphous semiconductor thermoelectric material of the thermoelectric element of the thermoelectric element assembly and each N
The amorphous semiconductor thermoelectric material is electrically connected alternately to a high temperature side and a low temperature side, and is connected in series as a whole, and has a flow path for flowing a high temperature fluid and a low temperature fluid separately. A thermoelectric power generation device characterized in that a fluid applies heat to the high temperature side of the thermoelectric element, and the low temperature fluid removes heat from the low temperature side of the thermoelectric element. 2. The thermoelectric power generation device according to claim 1, further comprising a nuclear reactor as a heat source for heating the high-temperature fluid. 3. Claim 1 or 2, wherein an inner layer and an outer layer are provided between the thermoelectric element assembly and the inner tube and between the thermoelectric element assembly and the outer tube, respectively, and are electrically a poor conductor and thermally a good conductor. The thermoelectric power generation device described. 4. Claims 1 and 2, wherein a high-temperature fluid is caused to flow through the inner tube of the thermoelectric generator, and a low-temperature fluid is caused to flow through the outer surface of the outer tube of the thermoelectric generator.
or the thermoelectric power generation device according to 3. 5. Claims 1 and 2, wherein a low temperature fluid is caused to flow through the inner tube of the thermoelectric generator, and a high temperature fluid is caused to flow through the outer surface of the outer tube of the thermoelectric generator.
or the thermoelectric power generation device according to 3. 6. Claims 1, 2, 3, and 4, wherein the thermoelectric generator has a large number of thermoelectric generators, and the electrical connection between the thermoelectric generators is series, parallel, or a combination of series and parallel. or the thermoelectric power generation device according to 5. 7. The thermoelectric power generation device according to claim 1, 2, 3, 4, 5, or 6, wherein both the P-type amorphous semiconductor thermoelectric material and the N-type amorphous semiconductor thermoelectric material are made of FeSi_2. 8. Claims 1, 2, 3, 4, 5, 6, or 8, wherein the high-temperature fluid that imparts heat to the high-temperature side of the thermoelectric element is a high-temperature molten metal, and the low-temperature fluid that removes heat from the low-temperature side of the thermoelectric element is water. 7. The thermoelectric power generation device according to 7. 9. Claim 8, wherein the high-temperature molten metal is high-temperature molten sodium.
The thermoelectric power generation device described. 10. The thermoelectric power generation device according to claim 1, 2, 3, 4, 5, 6, or 7, wherein the high-temperature fluid that provides heat to the high-temperature side of the thermoelectric element is a high-temperature gas. 11. The thermoelectric power generation device according to claim 10, wherein the high temperature gas is high temperature helium gas. 12. The thermoelectric power generation device according to claim 10, wherein the high temperature gas is a high temperature combustion gas. 13. The thermoelectric power generation device according to claim 10, wherein the high temperature gas is high temperature combustion exhaust gas. 14. Claims 1 and 2, wherein the thermoelectric generator has an airtight structure between the inner tube and the outer tube, and inert gas is supplied between the inner tube and the outer tube.
The thermoelectric power generation device according to 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13. 15. The thermoelectric power generation device according to claim 14, wherein the inert gas is helium. 16. The thermoelectric power generation device according to claim 14, wherein the inert gas is nitrogen. 17. The thermoelectric power generation device according to claim 14, 15 or 16, further comprising a gas pressure detector for detecting changes in the sealing pressure of the inert gas.