CN102710174B - Multistage temperature difference assembly, Blast Furnace Top Gas Recovery Turbine Unit (TRT) and electricity generation system - Google Patents

Abstract

The invention discloses a multi-stage thermoelectric power generation assembly, a power generation device and a power generation system. The multi-stage thermoelectric power generation assembly includes: a first heat conduction installation plate and a second heat conduction installation plate, which are arranged in parallel with each other at intervals, and the first heat conduction installation plate is close to the heat source side; a plurality of first-level thermoelectric modules located between the first heat-conducting mounting plate and the second heat-conducting mounting plate and a plurality of second-level thermoelectric modules located on the side of the second heat-conducting mounting plate away from the first heat-conducting mounting plate; the second A heat conduction switch, arranged between the first heat conduction mounting plate and the second heat conduction mounting plate, has a first position for thermal conduction between the first heat conduction mounting plate and the second heat conduction mounting plate and is connected with the first heat conduction mounting plate and/or the second heat conduction mounting plate Second position of the thermal disconnection of the second thermally conductive mounting plate. The present invention enables the overall thermal load to track and match changes in heat source temperature or heat flux density to the greatest extent by performing thermal management on thermoelectric power generation modules at all levels.

Description

Multi-stage thermoelectric power generation components, power generation device and power generation system

technical field

The invention relates to the field of thermoelectric power generation, in particular to a multi-stage thermoelectric power generation component, a power generation device and a power generation system.

Background technique

With the depletion of fossil energy and the increasingly severe change of the earth's climate, how to increase the utilization rate of renewable energy and reduce the emission of greenhouse gases has become a global energy issue and technical challenge.

Thermoelectric power generation (thermoelectric) technology is a technology that uses the migration of microscopic particles (electrons or holes) in semiconductor thermoelectric materials to directly convert heat flow generated by temperature differences into electrical energy. This technology matured in the 1950s, and it was mainly used to power spacecraft and field communication equipment in the early stage, and it was also used for civilian use later.

The thermoelectric generator is only composed of a solid structure, does not contain gas and liquid circulating fluids, and has no moving parts. It can be made into any size and shape and installed in various occasions. Another advantage of thermoelectric power generation technology is that it can use low-quality heat sources. In theory, as long as there is a temperature difference, it can generate electricity. At the same time, it has strong adaptability. Changes in temperature parameters within 200°C will not affect the normal operation of the thermoelectric generator. Therefore, thermoelectric power generation technology is expected to be widely used in waste heat recovery of power plants or chemical plants, as well as utilization of renewable energy such as geothermal energy, ocean energy, and solar energy.

Theoretically, the efficiency and power of the thermoelectric generator increase significantly with the increase of the temperature difference between the hot and cold ends, but in practice, due to the limited temperature range of a thermoelectric material, multi-level components are usually used, that is, multiple A composite assembly in which thermoelectric power generation modules made of different thermoelectric materials are connected in series.

At present, the common practice in the industry is to design the power matching of all levels according to the rated working conditions, and then directly stack and install the designed and processed multi-level modules. After research, the applicant found that: the multi-stage thermoelectric power generation device in the prior art adopts the method of fixed heat load, which is highly efficient for the utilization of stable heat sources, but it can be used for solar energy that often changes periodically or randomly. Without a regenerative heat source, the average operating efficiency of such a thermoelectric generator will drop significantly.

Contents of the invention

The purpose of the present invention is to provide a multi-stage thermoelectric power generation assembly to improve the operating efficiency when using an unstable heat source. The purpose of the present invention is also to provide a power generation device and a power generation system having the multi-stage thermoelectric power generation assembly.

Therefore, according to one aspect of the present invention, a multi-stage thermoelectric power generation assembly is provided, including: a first heat conduction mounting plate and a second heat conduction mounting plate, arranged in parallel with each other at intervals, the first heat conduction mounting plate is close to the heat source side; A plurality of first-level thermoelectric modules between a heat-conducting mounting plate and a second heat-conducting mounting plate and a plurality of second-level thermoelectric modules located on a side of the second heat-conducting mounting plate away from the first heat-conducting mounting plate; a first heat-conducting switch, It is arranged between the first heat conduction mounting plate and the second heat conduction mounting plate, and has a first position for thermally conducting the first heat conduction mounting plate and the second heat conduction mounting plate and is connected with the first heat conduction mounting plate and/or the second heat conduction mounting plate Second position for thermal disconnect.

Further, the above-mentioned multi-stage thermoelectric power generation assembly further includes a first driver, which drives the first heat conduction switch to switch between the first position and the second position.

Further, the above-mentioned first heat conduction mounting plate and the second heat conduction mounting plate are provided with an integrally penetrated mounting hole, and the first heat conduction switch is rotatably arranged in the mounting hole around an axis perpendicular to the surface of the first heat conduction mounting plate, The first position and the second position are respectively a first rotational position and a second rotational position.

Further, the above-mentioned first heat conduction switch includes a first rotating shaft and a first group of thermal contact protrusions on the outer periphery of the first rotation shaft, wherein the installation hole of the first heat conduction mounting plate is provided with The thermal contact recess.

Further, the above-mentioned first heat conduction switch also includes a second group of thermal contact protrusions on the outer circumference of the first rotating shaft, wherein the installation hole of the second heat conduction mounting plate is provided with a thermal contact that matches the second group of thermal contact protrusions. In the concave part, the first heat conduction switch is thermally conducted or disconnected with the first heat conduction mounting plate and the second heat conduction mounting plate at the same time.

Further, both ends of the above-mentioned first rotating shaft are respectively provided with support bearings.

Further, the above-mentioned first driver is an electromagnetic relay, and the electromagnetic relay includes an electromagnet body, a push rod located in the electromagnet body, and a stick at the end of the push rod, wherein a torsion bar is provided on the outer circumference of the first rotating shaft, The stick is flexibly connected with the torsion bar.

Further, the above-mentioned first heat conduction switch includes a first rotating shaft and a second group of thermal contact protrusions arranged on the outer periphery of the first rotation shaft, wherein, the installation hole of the second heat conduction mounting plate is provided with Fitting thermal contact recess.

Further, the above-mentioned multi-stage thermoelectric power generation assembly also includes a third heat-conducting mounting plate located on a side of the second heat-conducting mounting plate away from the first heat-conducting mounting plate, and a third heat-conducting mounting plate located on a side of the third heat-conducting mounting plate The third-level thermoelectric module and the second heat conduction switch, wherein the second heat conduction switch is always in thermal conduction with the first heat conduction switch, and is in selective thermal conduction with the third heat conduction mounting plate.

Further, the third heat conduction mounting plate is provided with a mounting hole, the mounting hole on the third heat conduction mounting plate is integrated with the mounting hole on the first heat conduction mounting plate and the mounting hole on the second heat conduction mounting plate, and the second heat conduction switch It is rotatably arranged in the mounting hole around an axis perpendicular to the plate surface of the first heat conduction mounting plate, and the second heat conduction switch has a third rotation position in thermal conduction with the third heat conduction mounting plate and disconnected from the third heat conduction mounting plate Fourth rotational position of thermal conduction.

Further, the above-mentioned second heat conduction switch includes a second rotating shaft and a third group of thermal contact protrusions arranged on the outer periphery of the second rotational shaft, wherein, the installation hole of the third heat conduction mounting plate is provided with Fitting thermal contact recess.

Further, the above-mentioned multi-stage thermoelectric power generation assembly further includes a second driver for driving the second heat conduction switch to switch between the third rotation position and the fourth rotation position.

Further, the plurality of first-level thermoelectric modules and the plurality of second-level thermoelectric modules are arranged around the installation hole centered on the installation hole.

According to another aspect of the present invention, a multi-stage thermoelectric power generation device is provided, including a base plate, a top plate near the heat source side, a multi-stage thermoelectric power generation assembly as described above between the top plate and the bottom plate, and a multi-stage temperature difference The heat-insulating side wall arranged on the outer periphery of the power generation component.

The present invention also provides a multi-stage thermoelectric power generation system, including: the multi-stage thermoelectric power generation device described above; a temperature detection device for detecting the temperature of the top plate on the heat source side of the multi-stage thermoelectric power generation device; The device is electrically connected to the driver of the multi-stage thermoelectric power generation device, and controls the action of the first heat conduction switch of the multi-stage thermoelectric power generation assembly in the multi-stage thermoelectric power generation device according to the temperature detected by the temperature detection device.

The present invention performs thermal management on the thermoelectric power generation modules at all levels, that is, changes the connection status of the thermoelectric power generation modules at all levels in real time through the heat conduction switch, so that the overall thermal load can track and match the change of the heat source temperature or heat flux density to the greatest extent.

In addition to the purposes, features, and advantages described above, other purposes, features, and advantages of the present invention will be further described in detail with reference to the accompanying drawings.

Description of drawings

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate preferred embodiments of the invention and together with the description serve to explain the principle of the invention. In the picture:

Fig. 1 is a schematic diagram of a multi-stage thermoelectric power generation assembly according to a first embodiment of the present invention;

Fig. 2 is a schematic diagram of the multi-stage thermoelectric power generation assembly according to the present invention after the second heat-conducting mounting plate is removed, wherein the heat-conducting switch is in a state of thermal conduction with the first heat-conducting mounting plate;

Fig. 3 is a schematic diagram of the multi-stage thermoelectric power generation assembly according to the present invention after the second heat conduction mounting plate is removed, wherein the heat conduction switch is disconnected from the first heat conduction mounting plate;

Fig. 4 is a structural schematic diagram of the multi-stage thermoelectric power generation assembly according to the present invention after the heat conduction switch is removed;

Fig. 5 is a plane layout diagram of the multi-stage thermoelectric power generation assembly shown in Fig. 4;

Fig. 6 is a structural schematic diagram of a heat conduction switch according to the present invention;

FIG. 7 is a schematic top view of the heat conduction switch shown in FIG. 6;

Fig. 8 is a structural schematic diagram of a multi-stage thermoelectric power generation device according to the present invention;

Fig. 9 is a schematic layout diagram of a driver of a heat conduction switch according to the present invention;

Fig. 10 is a schematic structural view of the multi-stage thermoelectric power generation assembly according to the second embodiment of the present invention after the conductive switch is removed;

Fig. 11 is a structural schematic diagram of a heat conduction switch adapted to the multi-stage thermoelectric power generation assembly shown in Fig. 10; and

Fig. 12 is a schematic diagram of a multi-stage thermoelectric power generation system according to the present invention.

Explanation of reference signs

10 multi-stage thermoelectric power generation components 11 first heat conduction mounting plate

12 Second heat conduction mounting plate 13 Mounting hole

14 First stage thermoelectric module 15 Second stage thermoelectric module

16 The first heat conduction switch 17 Electromagnetic relay

18 bottom plate 19 top plate

21 Insulation side wall 22 Support bearing

23 heat insulation pad 24 third heat conduction mounting plate

25 third stage thermoelectric module 26 second heat conduction switch

100 multi-stage thermoelectric power generation device

200 temperature detection device 300 controller

161 The first rotating shaft 162 The first group of thermal contact protrusions

163 second set of thermal contact protrusions 164 torsion bar

165 thermal interface material layer 171 electromagnet body

172 push rod 173 card stick

261 The second rotating shaft 262 The third group of thermal contact protrusions

111/121/241 thermal contact recesses 13a/13b/13c mounting holes.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways defined and covered by the claims.

1 to 3 are schematic diagrams of a multi-stage thermoelectric power generation assembly according to the first embodiment of the present invention. As shown in FIGS. The plates 12 are arranged parallel to each other at intervals, wherein, the first heat conduction mounting plate 11 and the second heat conduction mounting plate 12 are provided with an integrally penetrated mounting hole 13, and the first heat conduction mounting plate 11 is close to the heat source side; located on the first heat conduction mounting plate 11 A plurality of first-level thermoelectric modules 14 between the second heat-conducting mounting plate 12 and a plurality of second-level thermoelectric modules 15 located outside the second heat-conducting mounting plate 11; the first heat-conducting switch 16 surrounds the first heat-conducting mounting plate The axis perpendicular to the plate surface of 11 is rotatably arranged in the mounting hole 13, and has a first rotational position where the first heat conduction mounting plate 11 and the second heat conduction mounting plate 12 are thermally connected and a second rotational position where the thermal conduction is disconnected. ; and a driver (shown in FIGS. 8 and 9 ), which drives the first heat conduction switch 16 to switch between the first rotational position and the second rotational position.

The present invention realizes the short-circuit and disconnection of the first-stage thermoelectric module 14 through a first heat-conducting switch 16 that can be thermally conducted or disconnected between the first heat-conducting mounting plate 11 and the second heat-conducting mounting plate 12, thereby having a function according to the heat source The ability to change the access status of heat loads at all levels in real time with changes in temperature and heat flux.

Fig. 4 and Fig. 5 are structural schematic diagrams of the multi-stage thermoelectric power generation assembly according to the present invention after the heat conduction switch is removed. As shown in FIG. 4 and FIG. 5 , a plurality of first-level thermoelectric modules 14 and a plurality of second-level thermoelectric modules 15 are arranged around the installation hole 13 with the installation hole 13 as the center.

In other embodiments, the location and size of the area where the mounting hole 13 is located can be adjusted as required.

6 and 7 are structural schematic diagrams of a heat conduction switch according to the present invention. As shown in FIGS. 6 and 7 , the first heat conduction switch 16 includes a rotating shaft 161 , a first group of thermal contact protrusions 162 and a second group of thermal contact protrusions 163 located on the outer periphery of the rotating shaft. Wherein, the installation hole 13 a of the first heat conduction mounting plate 11 is provided with a thermal contact recess 111 matched with the first group of thermal contact protrusions 162 . The mounting hole 13 b of the second heat conducting mounting plate 12 is provided with a thermal contact recess 121 matching with the second group of thermal contact protrusions 163 .

Wherein, the positions of the first group of thermal contact protrusions 162 and the second group of thermal contact protrusions 163 meet the requirement that the first heat conduction switch 16 is thermally connected or disconnected from the first heat conduction mounting plate 11 and the second heat conduction mounting plate 12 at the same time.

Preferably, the first group of thermal contact protrusions 162 and thermal contact recesses 111 have a thermal interface material layer 165 to ensure the tight fit and good thermal contact of each thermal contact protrusion and thermal contact recess, and at the same time have wear resistance, resistance For high temperature and oxidation resistance, it can be made of common high temperature resistant thermal interface materials such as cast iron and ceramics, or it can be made of soft high thermal conductivity materials such as graphite and copper. Preferably, silicone grease is applied to the contact portion between the first group of thermal contact protrusions 162 and the thermal contact recess 111 to increase the thermal conductivity between the first group of thermal contact protrusions 162 and the thermal contact recess 111 .

When the first heat conduction switch is turned to separate the first group of thermal contact protrusions and the second group of thermal contact protrusions from the corresponding thermal contact recesses, the heat flows along the first heat conduction mounting plate, the first stage thermoelectric module, the second heat conduction The order of the mounting plate and the second-stage thermoelectric module passes through sequentially, and both modules output power to the outside. The thermal conductivity of the heat conduction switch is very low, the first-stage thermoelectric module is thermally short-circuited, and the heat flow will flow sequentially along the first heat conduction mounting plate, the first heat conduction switch, the second heat conduction mounting plate, and the second-stage thermoelectric module. The secondary thermoelectric module outputs external power.

When the temperature of the heat source is high and the heat flow rate is large, the first heat conduction switch 16 is placed in the state of disconnecting heat conduction. At this time, the first-stage thermoelectric module and the second-stage thermoelectric module are all in working state; When the heat flow rate is low and the heat flow rate is small, the first heat conduction switch 16 is placed in the thermal conduction state. At this time, the first-stage thermoelectric module is thermally short-circuited and stops working, which is conducive to the optimal distribution of the temperature range and can reduce the internal resistance, thereby improving efficiency.

In this embodiment, the first group of thermal contact protrusions 162 and the second group of thermal contact protrusions 163 respectively include four thermal contact protrusions 111 uniformly distributed on the outer circumference of the rotating shaft. When the rotating shaft swings by 45°, the first heat conduction switch is switched between the heat conduction state and the heat conduction state.

In another embodiment, the numbers of the first group of thermal contact protrusions 162 and the second group of thermal contact protrusions 163 are three respectively. When the rotating shaft swings by 60°, the first heat conduction switch 16 is switched between the heat conduction state and the heat conduction state. In another other embodiment, the number of the first group of thermal contact protrusions 162 and the number of the second group of thermal contact protrusions 163 is 2 respectively. At this time, when the rotating shaft rotates 90°, the first heat conduction switch 16 is in thermal conduction. switch between the off state and off state.

In yet another embodiment, the number of the first group of thermal contact protrusions 162 and the second group of thermal contact protrusions 163 is one respectively. At this time, when the rotating shaft rotates 180°, the first heat conduction switch 16 is in thermal conduction. switch between the off state and off state.

In the above embodiments, the first heat conduction switch 16 is thermally connected or disconnected from the first heat conduction mounting plate 11 and the second heat conduction mounting plate 12 at the same time. In other embodiments, the first heat conduction switch is always in thermal conduction with one of the first heat conduction mounting plate or the second heat conduction mounting plate, and is selectively in heat conduction or disconnection with the other.

In the present invention, the temperature adapted to the first-stage thermoelectric module is higher than the temperature range adapted to the second-stage thermoelectric module. It is 150~100℃.

Fig. 8 is a structural schematic diagram of a power generation device with multi-stage thermoelectric power generation components according to the present invention. As shown in FIG. 8 , the power generation device 100 includes a bottom plate 18 , a top plate 19 close to the heat source side, a multi-stage thermoelectric power generation assembly 10 , and an adiabatic side wall 21 arranged around the bottom plate 18 , top plate 19 and the multi-stage thermoelectric power generation assembly 10 .

In this embodiment, the two ends of the first heat conduction switch 16 respectively have support bearings 22 to increase the flexibility of the first heat conduction switch 16 to rotate around its own axis. The positions where the support bearings 22 are installed on the top plate and the bottom plate are provided with heat insulating pads 23 .

In other embodiments, the two ends of the first heat conduction switch 16 are conical heads respectively, the top plate and the bottom plate are respectively provided with heat insulating blocks, and the heat insulating blocks are provided with pits for positioning and matching with the tapered heads. So that the first heat conduction switch 16 can rotate freely. Of course, the positions of the conical head and the dimple can also be interchanged.

The first heat conduction switch, the bottom plate, the first heat conduction mounting plate, the second heat conduction mounting plate, and the top plate are all made of materials with high thermal conductivity, such as copper, aluminum, aluminum nitride and other materials. When the first thermal conduction switch is in the thermal conduction state, the thermal resistance is less than 1/100 of the total thermal resistance of any one-stage thermoelectric module, so as to ensure an effective thermal short circuit.

The heat insulation pad and the heat insulation side wall are preferably made of materials such as glass fiber-aluminum foil composite film with a thermal conductivity lower than 0.1W/mk.

Fig. 9 is a schematic layout diagram of a driver of a heat conduction switch according to the present invention. As shown in Figure 9, the first driver is an electromagnetic relay 17, and the electromagnetic relay 17 includes an electromagnet body 171, a push rod 172 positioned in the electromagnet body 171, and a stick 173 positioned at the end of the push rod 172, wherein the rotating shaft 161 A torsion bar 164 is arranged on the outer periphery of the torsion bar 164, and the stick 173 is movably connected with the torsion bar 164.

In other embodiments, a rack is formed on the push rod, a gear is formed on the rotating shaft, and a rack and pinion transmission pair is formed between the push rod and the rotating shaft to drive the rotating shaft to rotate through the telescopic movement of the pendulum. The angle can be increased, for example 90° or 180°.

In the above-mentioned embodiments of the present invention, the first heat conduction switch rotates in the mounting hole to achieve thermal conduction or thermal disconnection with the first heat conduction mounting plate and the second heat conduction mounting plate. In other embodiments, the first heat conduction switch A heat conduction switch moves up and down in a direction perpendicular to the first heat conduction mounting plate, realizing thermal conduction or thermal disconnection between the first heat conduction mounting plate and the second heat conduction mounting plate.

The present invention is not only applicable to two-stage thermoelectric modules, but also three-stage or above power generation modules. The thermoelectric power generation components of the three-level power generation module will be described in detail below.

Fig. 10 is a schematic structural diagram of the multi-stage thermoelectric power generation assembly according to the second embodiment of the present invention after the conductive switch is removed. As shown in FIG. 10 , in this embodiment, the multi-stage thermoelectric power generation assembly further includes a third heat-conducting mounting plate 24 located outside the second heat-conducting mounting plate 12 , and a third-stage thermoelectric module 25 located outside the third heat-conducting mounting plate 24 , and the second heat conduction switch 26 , wherein the second heat conduction switch 26 is always in thermal conduction with the first heat conduction switch 16 , and is in selective heat conduction with the third heat conduction mounting plate 24 .

Preferably, the third heat conducting mounting plate 24 is provided with mounting holes 13c, and the mounting holes 13c on the third heat conducting mounting plate 24 are integrated with the mounting holes 13a, 13b on the first heat conducting mounting plate 11 and the second heat conducting mounting plate 12 Through, the second heat conduction switch 26 is rotatably arranged in the installation hole around the axis perpendicular to the plate surface of the first heat conduction mounting plate, and the second heat conduction switch 26 has a third rotation position in thermal conduction with the third heat conduction mounting plate 24 And the fourth rotational position where the thermal conduction with the third heat conducting mounting plate 24 is disconnected.

In this embodiment, three working modes are realized: the first-level, second-level and third-level thermoelectric modules work simultaneously; the second-level and third-level thermoelectric modules work simultaneously; and the third-level thermoelectric modules work independently.

Fig. 11 is a structural schematic diagram of a heat conduction switch adapted to the multi-stage thermoelectric power generation assembly shown in Fig. 10 . As shown in FIG. 11 , the second heat conduction switch 26 includes a rotating shaft 261 and a third group of thermal contact protrusions 262 arranged on the outer periphery of the rotating shaft 261 , wherein the mounting hole 13c of the third heat conducting mounting plate 24 is provided with a third group of heat contact protrusions 262 . The thermal contact recess 241 is mated with the contact protrusion 262 . Preferably, the shaft 261 of the second heat conduction switch 26 and the shaft 161 of the first heat conduction switch 16 form a sleeve structure.

The second heat conduction switch 26 is independently driven by another driver, and the driver preferably also adopts an electromagnetic relay. The structure of the electromagnetic relay can be the same as that of the first heat conduction switch 26 , which will not be described in detail here.

Fig. 12 is a schematic diagram of a multi-stage thermoelectric power generation system according to the present invention. As shown in Figure 12, the multi-stage thermoelectric power generation system includes: a multi-stage thermoelectric power generation device 100; a temperature detection device 200 that detects the top plate temperature on the heat source side of multiple thermoelectric power generation devices; The driver electrically connected to the controller 300 controls the action of the driver according to the temperature change of the top plate.

The temperature detection device 200, such as a thermocouple, detects the temperature change of the top plate. The controller calculates the temperature threshold for judging whether the modules of this level are working according to the electrical and thermal parameters of the modules of each level. During the movement, the thermal conduction or disconnection of the thermoelectric modules at all levels is controlled according to the change of the top plate temperature, so as to maximize the overall efficiency.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (15)

1. A multi-stage thermoelectric power generation assembly, characterized in that it comprises: The first heat conduction mounting plate (11) and the second heat conduction mounting plate (12) are arranged in parallel and spaced apart from each other, and the first heat conduction mounting plate (11) is close to the heat source side; A plurality of first-stage thermoelectric modules (14) located between the first heat-conducting mounting plate (11) and the second heat-conducting mounting plate (12) and a part of the second heat-conducting mounting plate (12) that is far away from the first A plurality of second-stage thermoelectric modules (15) on one side of a heat-conducting mounting plate (11); The first heat conduction switch (16), arranged between the first heat conduction mounting plate (11) and the second heat conduction mounting plate (12), has the function of heat conduction between the first heat conduction mounting plate (11) and the second heat conduction mounting plate (11) and the second heat conduction mounting plate (12). The first position of the two heat-conducting mounting plates (12) and the second position thermally disconnected from the first heat-conducting mounting plate (11) and/or the second heat-conducting mounting plate (12). 2. The multi-stage thermoelectric power generation assembly according to claim 1, further comprising a first driver for driving the first heat conduction switch (16) to switch between the first position and the second position. 3. The multi-stage thermoelectric power generation assembly according to claim 2, characterized in that, the first heat conduction mounting plate (11) and the second heat conduction mounting plate (12) are provided with an integrally penetrating mounting hole (13), The first heat conduction switch (16) is rotatably arranged in the installation hole (13) around an axis perpendicular to the surface of the first heat conduction mounting plate (11), and the first position and the second position are the first rotational position and the second rotational position, respectively. 4. The multi-stage thermoelectric power generation assembly according to claim 3, characterized in that, the first heat conduction switch (16) comprises a first rotating shaft (161) and a first group of A thermal contact protrusion (162), wherein a thermal contact recess (111) matching the first group of thermal contact protrusions (162) is provided in the installation hole (13a) of the first heat conduction mounting plate (11) ). 5. The multi-stage thermoelectric power generation assembly according to claim 4, characterized in that, the first heat conduction switch (16) further comprises a second group of thermal contact protrusions (163) on the outer periphery of the first rotating shaft (161) ), wherein, the installation hole (13b) of the second heat conduction mounting plate (12) is provided with a heat contact recess (121) matching with the second group of heat contact protrusions (163), and the first heat conduction switch (16) Thermal conduction or disconnection with the first heat conduction mounting plate (11) and the second heat conduction mounting plate (12) at the same time. 6. The multi-stage thermoelectric power generation assembly according to claim 4, characterized in that, two ends of the first rotating shaft (161) are respectively provided with supporting bearings (22). 7. The multi-stage thermoelectric power generation assembly according to claim 4, characterized in that, the first driver is an electromagnetic relay (17), and the electromagnetic relay (17) includes an electromagnet body (171), located on the electromagnet body the push rod (172) in (171), and the stick (173) at the end of the push rod (172), wherein a torsion bar (164) is provided on the outer circumference of the first rotating shaft (161), The stick (173) is movably connected with the torsion bar (164). 8. The multi-stage thermoelectric power generation assembly according to claim 3, characterized in that, the first heat conduction switch (16) comprises a first rotating shaft (161) and a second rotating shaft (161) arranged on the outer circumference A set of thermal contact protrusions (163), wherein a thermal contact recess ( 121). 9. The multi-stage thermoelectric power generation assembly according to claim 4, characterized in that it further comprises a third heat-conducting mounting plate (12) on a side away from the first heat-conducting mounting plate (11). A heat conduction mounting plate (24), a third-stage thermoelectric module (25) located on a side of the third heat conduction mounting plate (24) away from the first heat conduction mounting plate (11), and a second heat conduction switch (26 ), wherein the second heat conduction switch (26) is always in thermal conduction with the first heat conduction switch (16), and is in selective thermal conduction with the third heat conduction mounting plate (24). 10. The multi-stage thermoelectric power generation assembly according to claim 9, characterized in that, the third heat conduction mounting plate (24) is provided with mounting holes (13c), and the third heat conduction mounting plate (24) is provided with mounting holes (13c). The mounting hole (13c) is integrated with the mounting hole (13a) of the first heat conduction mounting plate (11) and the mounting hole (13b) on the second heat conduction mounting plate (12), and the second heat conduction switch (26) The second heat conduction switch (26) has a (24) The third rotation position of thermal conduction and the fourth rotation position of disconnection of thermal conduction with the third heat conduction mounting plate (24). 11. The multi-stage thermoelectric power generation assembly according to claim 10, characterized in that, the second heat conduction switch (26) comprises a second rotating shaft (261) and a third rotating shaft (261) arranged on the outer periphery of the second rotating shaft (261). A set of thermal contact protrusions (263), wherein a thermal contact recess ( 241). 12. The multi-stage thermoelectric power generation assembly according to claim 11, further comprising a second driver for driving the second heat conduction switch (26) to switch between the third rotation position and the fourth rotation position . 13. The multi-stage thermoelectric power generation assembly according to claim 3, characterized in that, the plurality of first-stage thermoelectric modules (14) and the plurality of second-stage thermoelectric modules (15) are connected by the mounting holes (13) Arranged around the installation hole (13) as the center. 14. A multi-stage thermoelectric power generation device, characterized in that it comprises a bottom plate (18), a top plate (19) close to the heat source side, and a wall according to claims 1 to 13 between the top plate (19) and the bottom plate (18). The multi-stage thermoelectric power generation assembly (10) described in any one of the above, and the heat-insulating side wall (21) provided on the outer periphery of the multi-stage thermoelectric power generation assembly (10). 15. A multi-stage thermoelectric power generation system, characterized in that it comprises: The multi-stage thermoelectric power generation device (100) according to claim 14; A temperature detection device (200), detecting the temperature of the top plate (19) on the heat source side of the multi-stage thermoelectric power generation device (100); A controller (300), electrically connected to the driver of the temperature detection device (200) and the multi-stage thermoelectric power generation device (100), controls the multi-stage thermoelectric power generation device according to the temperature detected by the temperature detection device (200) The action of the first heat conduction switch (16) of the multi-stage thermoelectric power generation assembly (10) in (100).