阅读说明：本技术 堆芯余热排出的系统和堆芯余热排出的热电换热器 (System for discharging reactor core waste heat and thermoelectric heat exchanger for discharging reactor core waste heat ) 是由 李旭东 李勇 李轶 王苏豪 徐建军 黄彦平 于 2020-06-23 设计创作，主要内容包括：本发明公开了堆芯余热排出的系统和堆芯余热排出的热电换热器,所述系统包括从反应堆堆芯一回路导出的余热排出回路,所述余热排出回路上所设的换热单元为热电换热器(8),所述热电换热器(8)采用板式换热器为本体结构,所述板式换热器中的板片(81)采用内嵌有热电半导体(811)的板片；热电半导体(811)引出电能导接于反应堆堆芯一回路中的主泵(6)。本发明主要应用在核动力安全关键设备领域,基于一回路、设备冷却水系统回路、海水回路,利用热电转换技术,将全厂断电事故工况下的堆芯余热直接转化成电能,带走一部分堆芯余热的同时,以一定功率继续维持主泵运转继送冷却剂,从而排出堆芯余热,实现堆芯长期冷却。(The invention discloses a system for discharging reactor core waste heat and a thermoelectric heat exchanger for discharging the reactor core waste heat, wherein the system comprises a waste heat discharge loop led out from a reactor core loop, a heat exchange unit arranged on the waste heat discharge loop is a thermoelectric heat exchanger (8), the thermoelectric heat exchanger (8) adopts a plate type heat exchanger as a body structure, and a plate sheet (81) in the plate type heat exchanger adopts a plate sheet embedded with a thermoelectric semiconductor (811); the thermoelectric semiconductor (811) leads electric energy to a main pump (6) in a loop of the reactor core. The invention is mainly applied to the field of nuclear power safety key equipment, based on a primary circuit, an equipment cooling water system circuit and a seawater circuit, utilizes a thermoelectric conversion technology to directly convert reactor core waste heat under the working condition of a plant outage accident into electric energy, takes away part of the reactor core waste heat, and simultaneously continuously maintains the operation of a main pump at a certain power to deliver coolant, thereby discharging the reactor core waste heat and realizing the long-term cooling of the reactor core.)

1. The system for discharging the waste heat of the reactor core comprises a waste heat discharging loop led out from a reactor core loop, and is characterized in that a heat exchange unit arranged on the waste heat discharging loop is a thermoelectric heat exchanger (8), the thermoelectric heat exchanger (8) adopts a plate type heat exchanger as a body structure, and a plate sheet (81) in the plate type heat exchanger adopts a plate sheet embedded with a thermoelectric semiconductor (811); the thermoelectric semiconductor (811) leads electric energy to a main pump (6) in a loop of the reactor core.

2. The system for discharging the residual heat of the core as claimed in claim 1,

slab (81) among the plate heat exchanger is double-deck splint structure, and this double-deck splint structure includes that 1 layer is adjacent to metal heat-conducting plate (812) of cold interval (816) and 1 layer is adjacent to metal heat-conducting plate (812) of hot interval (815), and 2 layers of metal heat-conducting plate opposite faces are provided with insulating coating (813), thermoelectric semiconductor imbeds between insulating coating, the hot interval is the runner that is used for circulating the hot-fluid in the plate heat exchanger, the cold interval is the runner that is used for circulating the cold fluid in the plate heat exchanger.

3. The system for discharging the residual heat of the core as claimed in claim 1,

a reactor core primary circuit comprising: the RCS cold pipe section is communicated with the reactor core through the main pump (6), the backwater section is communicated with the steam generator (4) through the main pump (6), and the RCS hot pipe section is communicated with the steam generator (4) through the reactor core;

the hot incoming end (819) of the plate heat exchanger is connected with the RCS heat pipe section of the steam generator (4) from the reactor core of the reactor core primary loop through a hot section branch of the waste heat discharge loop;

the hot return water end (819) of the plate heat exchanger is connected with a transition pipe section from a main pump (6) of a reactor core primary circuit to a steam generator (4) through a cold section branch of a waste heat discharge circuit;

a normally closed solenoid valve B1(7) is arranged on the hot section branch, a normally closed solenoid valve B2(9) is arranged on the cold section branch,

the connecting point of the hot section branch and the RCS heat pipe section is a node A, a normally open electromagnetic valve A1(3) is arranged on the RCS heat pipe section from the node A to the steam generator (4), the connecting point of the cold section branch and the transition pipe section is a node B, and a normally open electromagnetic valve A2(5) is arranged on the return water section from the node B to the steam generator (4).

4. The system for discharging the residual heat of the core as claimed in claim 1,

the device is characterized by further comprising an equipment cooling water system (14), wherein the equipment cooling water system (14) comprises an equipment cooling water system shell-and-tube heat exchanger (15), and a cold connecting end (817) and a cold water returning end (818) of a loop plate type heat exchanger where the equipment cooling water system shell-and-tube heat exchanger (15) is located; the equipment cooling water system pipe shell heat exchanger (15) exchanges heat with an external cold source;

the equipment cooling water system (14) further comprises a pressure stabilizing tank (10), and the pressure stabilizing tank (10) is communicated with a loop where the shell-and-tube heat exchanger (15) of the backup cooling water system is located.

5. The thermoelectric heat exchanger with the waste heat discharged from the reactor core is characterized in that the thermoelectric heat exchanger (8) adopts a plate type heat exchanger as a body structure, and a plate sheet (81) in the plate type heat exchanger adopts a plate sheet embedded with a thermoelectric semiconductor (811).

6. The core waste heat-discharging thermoelectric heat exchanger of claim 5, wherein the plate sheets in the plate heat exchanger are of a double-layer clamping plate structure, the double-layer clamping plate structure comprises 1 layer of metal heat-conducting plate (812) adjacent to a cold space and 1 layer of metal heat-conducting plate (812) adjacent to a hot space, the opposite surfaces of the 2 layers of metal heat-conducting plates are provided with insulating coatings (813), the thermoelectric semiconductor is embedded between the insulating coatings, the cold space is a flow channel for circulating hot fluid in the plate heat exchanger, and the cold space is a flow channel for circulating cold fluid in the plate heat exchanger.

7. The core waste heat removal thermoelectric heat exchanger of claim 6, wherein a gap is formed between the insulating coatings, both ends of the thermoelectric semiconductor are respectively inserted into the insulating coatings or both ends of the thermoelectric semiconductor are respectively in flat contact with the surfaces of the insulating coatings, and at least one section of the thermoelectric semiconductor is arranged in the gap.

8. The core waste heat removal thermoelectric heat exchanger of claim 6, wherein zero gaps exist between the insulating coatings, and both ends of the thermoelectric semiconductor are respectively inserted into the insulating coatings.

9. The core waste heat removal thermoelectric heat exchanger as recited in claim 6, wherein the thermoelectric semiconductors comprise P-type semiconductor thermoelectric elements and N-type semiconductor thermoelectric elements, the P-type semiconductor thermoelectric elements and the N-type semiconductor thermoelectric elements are integrally arranged in a rectangular array, each row in the overall rectangular array is the P-type semiconductor thermoelectric elements and the N-type semiconductor thermoelectric elements which are arranged at intervals, and the P-type semiconductor thermoelectric elements and the N-type semiconductor thermoelectric elements are connected in series through metal wires (814) embedded in the insulating coating.

10. The core waste heat removal thermoelectric heat exchanger of claim 6, wherein the insulating coatings are supported and sealed by gaskets, and the gaskets are arranged at the edge positions of the plates.

Technical Field

The invention relates to the field of reactor system design, in particular to a thermoelectric heat exchanger for discharging reactor core waste heat and a reactor core waste heat discharging system formed by the thermoelectric heat exchanger.

Background

The waste heat removal system is an important component in the reactor core cooling equipment for realizing three safety functions of the reactor, is always the focus of attention in the research, design and operation processes of the reactor system, and particularly forms the design ideas of the reactor core waste heat removal system of a passive technology represented by AP1000 and an increased special safety system represented by EPR in the global scope after the Fudao nuclear accident: the former utilizes the principles of gravity of materials, natural convection, diffusion, evaporation, condensation and the like of fluid to cool a reactor plant and take away waste heat of a reactor core in an accident emergency; the latter adds and strengthens the special safety system on the basis of the second generation nuclear power technology to improve the safety performance. As shown in fig. 1, the existing passive waste heat removal design concept is to use a passive tubular heat exchanger 8-1 as a heat exchange unit, which is arranged in a pool, when a safety accident occurs, a waste heat removal loop is started, an RCS heat pipe section of the loop is introduced into the passive tubular heat exchanger 8-1, and the passive tubular heat exchanger 8-1 is utilized to exchange heat with the pool, so as to achieve waste heat removal.

Although the passive design concept has the characteristics of simplifying system equipment, avoiding human intervention for a long time and the like, the natural circulation system with multiple coupling factors has the characteristic of being easily influenced by the external environment, and once the external working condition expected by over-design exists, the system has the risk of overall failure. The design of increasing the special safety adopts the concept of increasing the safety redundancy and diversity, so that the construction cost of the nuclear power station is increased; on the other hand, the nuclear accident coping strategy becomes more complex, and the uncertainty of accident handling safety is increased.

Disclosure of Invention

The invention aims to provide a thermoelectric heat exchanger which can be suitable for discharging waste heat of a reactor core, and provides a waste heat discharging system based on the thermoelectric heat exchanger. The thermoelectric heat exchanger can directly convert heat of a waste heat discharge loop into electric energy, and then the electric energy is utilized to prolong the idling time of a main pump, so that the temperature of a reactor core is prevented from rising due to the fact that the main pump is disconnected and is in a passive condition and the loop is in a low-speed circulation state when a safety accident happens; the passive and active mutual matching design concept is adopted, so that a passive waste heat discharge system is formed to generate electric energy to form an active extension of the underwater rotation time and maintain the flow of a loop, and the higher reliability of the system is improved.

The invention is realized by the following technical scheme:

the system for discharging the waste heat of the reactor core comprises a waste heat discharging loop led out from a reactor core loop, and is characterized in that a heat exchange unit arranged on the waste heat discharging loop is a thermoelectric heat exchanger, the thermoelectric heat exchanger adopts a plate type heat exchanger as a body structure, and plates in the plate type heat exchanger adopt plates embedded with thermoelectric semiconductors; the electric energy led out by the thermoelectric semiconductor is connected with a main pump in a loop of the reactor core.

The invention aims to explain a comprehensive design concept combining passive and safety facility increase, which comprises the following steps: considering that the residual power of the reactor core is sharply reduced after the reactor is shut down due to an accident, the residual heat of the reactor core under the accident working condition is directly converted into electric energy through a thermoelectric conversion technology, and the main pump is continuously maintained to operate and deliver the coolant at a certain power while taking away a part of the residual heat of the reactor core, so that the reduction of the coolant flow is slowed down, the complete loss of the coolant is avoided, the residual heat of the reactor core shut down is carried away, the reactor core is cooled, the maximum temperature of a fuel cladding cannot exceed the accident limit value, and the serious consequences caused by the power failure accident of the whole plant are relieved and avoided. In conclusion, the conventional reactor core waste heat discharge system has safety advantages and disadvantages, adopts a thermoelectric conversion technology, and combines the comprehensive design concepts of passive and safety facility increase to integrate the advantages of two design ideas. Based on the design concept, the invention technology is obtained through technical innovation and experimental verification aiming at the experimental research of the novel reactor core waste heat discharge system of the reactor and supported by the major national safety basic research project.

The preferable further technical scheme is as follows: the slab among the plate heat exchanger is double-deck splint structure, and this double-deck splint structure includes 1 layer adjacent in cold spaced metal heat-conducting plate and 1 layer adjacent in hot spaced metal heat-conducting plate, and 2 layers of metal heat-conducting plate opposite faces are provided with insulating coating, thermoelectric semiconductor imbeds between insulating coating, the cold interval is the runner that is used for circulating the hot-fluid in the plate heat exchanger, the cold interval is the runner that is used for circulating the cold fluid in the plate heat exchanger.

The preferable further technical scheme is as follows: a reactor core primary circuit comprising: the RCS cold pipe section is communicated with the reactor core through a main pump, the transition pipe section is communicated with the steam generator through the main pump, and the RCS hot pipe section is communicated with the steam generator through the reactor core;

the hot connecting end of the plate heat exchanger is connected with the reactor core of the reactor core primary loop to the RCS heat pipe section of the steam generator through the hot section branch of the waste heat discharge loop;

the hot water return end of the plate heat exchanger is connected with a transition pipe section from the steam generator to a primary circuit main pump of the reactor through a cold section branch of the waste heat discharge loop;

a normally closed electromagnetic valve B1 is arranged on the hot section branch, a normally closed electromagnetic valve B2 is arranged on the cold section branch,

the preferable further technical scheme is as follows: the connecting point of hot section branch road and RCS heat pipe section is node A, is provided with normally open solenoid valve A1 on node A to steam generator's the RCS heat pipe section, and the connecting point of cold section branch road and the section of returning water is node B, is provided with normally open solenoid valve A2 on node B to steam generator's the section of returning water.

The preferable further technical scheme is as follows: the equipment cooling water system comprises an equipment cooling water system shell-and-tube heat exchanger, and a loop where the equipment cooling water system shell-and-tube heat exchanger is located is connected with a cold input end and a cold return end of the plate heat exchanger; the equipment cooling water system pipe shell heat exchanger exchanges heat with an external cold source;

the preferable further technical scheme is as follows: the equipment cooling water system also comprises a pressure stabilizing tank which is communicated with a loop where the shell-and-tube heat exchanger of the backup cooling water system is located.

In order to realize the system, the invention needs to design a thermoelectric heat exchanger suitable for discharging the waste heat of the reactor core, and in order to obtain the thermoelectric heat exchanger, the invention adopts a design concept based on the reappearance of the design concept of the existing plate heat exchanger, and the design concept of the thermoelectric heat exchanger is as follows: on the basis of taking a plate heat exchanger as a body, a plate in the plate heat exchanger is improved, a plate embedded with a thermoelectric semiconductor is designed, and because two sides of the plate are two fluids with different temperatures, the two sides of the plate actually have temperature difference; and then the electric energy is utilized to drive the main pump to continue to operate.

The calculation result shows that the thermoelectric conversion efficiency of 5% of the existing mature thermoelectric semiconductor is taken as a reference, the thermoelectric conversion reactor core waste heat discharge system is adopted to deal with the power failure accident of a whole plant of a million kilowatt nuclear power unit, the normalized flow of the reactor core can be kept above the normalized power level of the reactor core for a long time, and the maximum temperature of the fuel cladding is kept below the limit value of 1200 ℃ under the accident working condition for a long time. The reactor core waste heat discharge system can effectively lead out the reactor core waste heat after the power failure accident of the whole plant occurs, prevent the cladding from being damaged and the reactor core from being melted, and prevent radioactive substances from leaking.

In order to realize the above concept, the invention provides a technical scheme as follows: the thermoelectric heat exchanger is of a plate type heat exchanger body structure, and the plate in the plate type heat exchanger is a plate embedded with a thermoelectric semiconductor.

The preferable further technical scheme is as follows: the slab among the plate heat exchanger is double-deck splint structure, and this double-deck splint structure includes 1 layer adjacent in cold spaced metal heat-conducting plate and 1 layer adjacent in hot spaced metal heat-conducting plate, and 2 layers of metal heat-conducting plate opposite faces are provided with insulating coating, thermoelectric semiconductor imbeds between insulating coating, the cold interval is the runner that is used for circulating the hot-fluid in the plate heat exchanger, the cold interval is the runner that is used for circulating the cold fluid in the plate heat exchanger.

The preferable further technical scheme is as follows: gaps exist among the insulating coatings, two ends of the thermoelectric semiconductor are respectively inserted into the insulating coatings or two ends of the thermoelectric semiconductor are respectively connected to the surfaces of the insulating coatings in a flat mode, and at least one section of the thermoelectric semiconductor is located in the gaps.

The preferable further technical scheme is as follows: zero gaps exist among the insulating coatings, and two ends of the thermoelectric semiconductor are respectively inserted into the insulating coatings.

The preferable further technical scheme is as follows: the thermoelectric semiconductor comprises a P-type semiconductor thermoelectric element and an N-type semiconductor thermoelectric element, the P-type semiconductor thermoelectric element and the N-type semiconductor thermoelectric element are integrally arranged in a rectangular array, each row in the integrally rectangular array is the P-type semiconductor thermoelectric element and the N-type semiconductor thermoelectric element which are arranged at intervals, and the P-type semiconductor thermoelectric element and the N-type semiconductor thermoelectric element are connected in series through a metal wire embedded in an insulating coating.

The preferable further technical scheme is as follows: and gaskets are adopted between the insulating coatings for supporting and sealing, and are arranged at the edge positions of the plates.

The invention can achieve the following effects:

the invention is mainly applied to the field of nuclear power safety key equipment, based on a primary circuit, an equipment cooling water system circuit and a seawater circuit, utilizes a thermoelectric conversion technology to directly convert reactor core waste heat under the working condition of a plant outage accident into electric energy, takes away part of the reactor core waste heat, and simultaneously continuously maintains the operation of a main pump at a certain power to deliver coolant, thereby discharging the reactor core waste heat and realizing the long-term cooling of the reactor core.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 is a schematic diagram of a prior art system.

Fig. 2 is a schematic system structure of the present application.

Fig. 3 is a schematic structural view of a thermoelectric heat exchanger.

Fig. 4 is a schematic cross-sectional view of a plate in a thermoelectric heat exchanger.

Figure 5 is a detailed schematic of the plate.

Reference numerals in the drawings denote:

1. a core; 2. a voltage regulator; 3. a normally open solenoid valve A1; 4. a steam generator; 5. a normally open solenoid valve A2; 6. a main pump; 7. a normally closed electromagnetic valve B1; 8. a thermoelectric heat exchanger; 9. a normally closed electromagnetic valve B2; 10. a surge tank; 11. seawater; 12. a circulating pump A; 13. a circulating pump B; 14. an equipment cooling water system; 15. a shell-and-tube heat exchanger of the equipment cooling water system; 8-1, a passive tube heat exchanger; 16. a power distribution unit; 81. a sheet; 811. a thermoelectric semiconductor; 812. a metal heat-conducting plate; 813. an insulating plating layer; 814. a metal wire; 815. a thermal interval; 816. cold spacing; 817. cold connecting the input end; 818. a cold return water end; 819. a thermal connection terminal; 820. and heating the water return end.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.