Molten salt-based nuclear power replacement thermal power transformation method and generator set

Abstract

The invention relates to the technical field of thermal power transformation, in particular to a nuclear power replacement thermal power transformation method based on fused salt and a generator set. The nuclear power replacement thermal power transformation method based on the fused salt comprises the steps that steam heat of a nuclear island steam generator is stored into fused salt of a fused salt assembly through a steam fused salt heat exchanger; heat of fused salt of the fused salt assembly is used for heating feed water of a water supply pipeline through a heat exchange assembly so as to generate steam, and the steam drives a steam turbine to work; and on the basis of the temperature and flow of the fused salt in the fused salt assembly and the pressure and flow of the feed water in the feed water pipeline, parameters of steam supplied to the steam turbine by the steam pipeline are controlled, so that thermodynamic system matching of the nuclear power reactor and the thermal power generating unit is achieved. According to the technical scheme, the thermodynamic system matching problem of an original thermal power generating unit and a nuclear power reactor can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power transformation, and in particular to a molten salt-based nuclear power replacement thermal power transformation method and a generator set. Background Art

[0003] From a functional perspective, both nuclear power and thermal power can be used as base load power sources. From a resource utilization perspective, thermal power is rigidly withdrawn when the remaining life is long, and the overall cost of decommissioning and dismantling existing thermal power plants is high. Therefore, nuclear power transformation of thermal power plants can utilize the grid access system, water sources, land, transmission facilities, and some process equipment and infrastructure resources of existing thermal power plants to reduce the overall cost of the power plant.

[0004] However, in the process of nuclear power transformation of thermal power units, there is a reactor-machine matching problem in which the steam parameters of the thermal system of the original thermal power unit do not match the steam parameters generated by the nuclear power reactor. Therefore, it is necessary to study a method for nuclear power transformation of thermal power units to solve the thermal system matching problem of the original thermal power unit and the nuclear power reactor while maintaining the original thermal power unit steam turbine generator system basically unchanged. Summary of the invention

[0005] In order to solve the problem of thermal system matching between the original thermal power unit and the nuclear power reactor, the embodiment of the present invention provides a molten salt-based nuclear power replacement thermal power transformation method and a generator set.

[0006] In a first aspect, an embodiment of the present invention provides a method for replacing thermal power with nuclear power based on molten salt, comprising:

[0007] The steam heat of the nuclear island steam generator is stored in the molten salt of the molten salt assembly by using a steam molten salt heat exchanger;

[0008] Using the heat exchange component to heat the feed water in the water supply pipeline with the molten salt heat of the molten salt component to generate steam, so that the steam drives the steam turbine to work;

[0009] Based on the temperature and flow of the molten salt in the molten salt assembly and the pressure and flow of the feed water in the feed water pipeline, the parameters of the steam supplied to the steam turbine are controlled to achieve thermal system matching between the nuclear power reactor and the thermal power unit.

[0010] In the second aspect, an embodiment of the present invention provides a molten salt-based generator set, which is applied to the method described in the above embodiment, including a nuclear island steam generator, a steam molten salt heat exchanger, a molten salt component, a heat exchange component, a water supply pipe, a steam turbine and a generator. The steam molten salt heat exchanger is respectively connected to the nuclear island steam generator and the molten salt component, and is used to store the steam heat of the nuclear island steam generator in the molten salt of the molten salt component. The heat exchange component is respectively connected to the molten salt component and the water supply pipe, and the steam turbine is connected to the heat exchange component through a steam pipe, and the steam turbine is connected to the generator. The steam parameters supplied by the steam pipe to the steam turbine are controlled by controlling the temperature and flow of the molten salt in the molten salt component and the pressure and flow of the feed water in the water supply pipe, so as to achieve thermal system matching between the nuclear power reactor and the thermal power unit.

[0011] The embodiment of the present invention provides a molten salt-based nuclear power replacement thermal power transformation method and a generator set, by setting a molten salt component to store the steam heat of the nuclear island steam generator in the molten salt of the molten salt component, and by controlling the temperature and flow of the molten salt in the molten salt component and the pressure and flow of the feed water in the feed water pipeline to control the steam parameters supplied to the turbine, so as to achieve thermal system matching between the nuclear power reactor and the thermal power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 This is a flow chart of a method for replacing thermal power with nuclear power based on molten salt provided in an embodiment of the present invention;

[0014] Figure 2 It is a schematic diagram of a nuclear power-coupled thermal power combined power generation unit provided in an embodiment of the present invention.

[0015] Reference numerals:

[0016] 1-nuclear island steam generator; 2-steam molten salt heat exchanger; 3-feedwater pipeline; 4-steam turbine; 5-generator; 6-hot salt tank; 7-hot salt pump; 8-cold salt tank; 9-cold salt pump; 10-first molten salt pipeline; 11-second molten salt pipeline; 12-molten salt electric heater; 13-superheater; 14-evaporator; 15-preheater; 16-reheater; 17-third molten salt pipeline; 18-thermal power main steam pipeline; 19-thermal power cold section pipeline; 20-thermal power hot section pipeline; 21-extraction steam feedwater heat exchanger; 22-extraction steam pipeline; 23-thermal power feedwater pump; 24-drain feedwater heat exchanger; 25-nuclear island feedwater pump. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] like Figure 1 and Figure 2 As shown, the method for replacing thermal power with nuclear power based on molten salt provided in an embodiment of the present invention comprises:

[0019] Step S1, using the steam molten salt heat exchanger 2 to store the steam heat of the nuclear island steam generator 1 into the molten salt of the molten salt assembly;

[0020] Step S2, using the heat exchange component to heat the feed water of the water supply pipe 3 with the molten salt heat of the molten salt component to generate steam, so that the steam drives the steam turbine 4 to work;

[0021] Step S3, based on the temperature and flow of the molten salt in the molten salt assembly and the pressure and flow of the feed water in the feed water pipe 3, control the steam parameters supplied to the steam turbine to achieve thermal system matching between the nuclear power reactor and the thermal power unit.

[0022] In this embodiment, a molten salt assembly is provided to store the steam heat of the nuclear island steam generator 1 in the molten salt of the molten salt assembly, and the steam parameters supplied to the steam turbine 4 are controlled by controlling the temperature and flow of the molten salt in the molten salt assembly and the pressure and flow of the feed water in the feed water pipe 3, so as to achieve thermal system matching between the nuclear power reactor and the thermal power unit.

[0023] It should be noted that the above-mentioned combined power generation unit is a transformation of the original thermal power using nuclear power. Among them, the nuclear power plant is mainly composed of a nuclear island reactor system, a conventional island steam turbine generator system and a whole plant auxiliary system. The thermal power plant is mainly composed of a boiler system, a main plant steam turbine generator system and a whole plant auxiliary system. The nuclear power transformation of a thermal power unit is to replace the boiler system of the thermal power unit with a nuclear island reactor system to provide a heat source for the power plant, and the other parts such as the steam turbine generator system of the original thermal power unit are reused as much as possible. In view of the thermal system mismatch problem existing in the nuclear power transformation of thermal power units, a method for replacing thermal power units with nuclear power based on a molten salt system is provided, which mainly uses the reactor of a high-temperature gas-cooled reactor nuclear power plant to replace the boiler of the thermal power plant, while the steam turbine generator system of the original thermal power unit remains unchanged.

[0024] In one embodiment of the present invention, the molten salt assembly includes a hot salt tank 6, a hot salt pump 7, a cold salt tank 8 and a cold salt pump 9, and the hot salt tank 6 and the cold salt tank 8 are connected by a first molten salt pipeline 10 and a second molten salt pipeline 11;

[0025] The steam heat of the nuclear island steam generator 1 is stored in the molten salt of the molten salt assembly by using the steam molten salt heat exchanger 2, including:

[0026] The cold molten salt in the cold salt tank 8 is supplied to the hot salt tank 6 via the first molten salt pipeline 10 by a cold salt pump 9 ; wherein the cold molten salt absorbs the steam heat of the nuclear island steam generator 1 while passing through the first molten salt pipeline 10 .

[0027] In one embodiment of the present invention, the molten salt assembly further includes a molten salt electric heater 12, which is disposed on the first molten salt pipeline 10 and is located between the steam molten salt heat exchanger 2 and the hot salt tank 6;

[0028] Also includes:

[0029] The molten salt flowing out of the steam molten salt heat exchanger 2 is further heated by the molten salt electric heater 12 .

[0030] In one embodiment of the present invention, the heat exchange assembly includes a superheater 13, an evaporator 14 and a preheater 15 which are sequentially arranged along the flow direction of the hot molten salt, and the preheater 15, the evaporator 14 and the superheater 13 are sequentially arranged along the flow direction of the feed water, and the outlet of the superheater 13 is connected to the steam turbine 4;

[0031] The heat exchange component is used to heat the water supply of the water supply pipe 3 with the molten salt heat of the molten salt component to generate steam, including:

[0032] The feed water in the feed water pipe 3 is heated in sequence by the preheater 15, the evaporator 14 and the superheater 13 to generate superheated steam.

[0033] In one embodiment of the present invention, the heat exchange component further includes a reheater 16, the second molten salt pipeline 11 is further connected in parallel with a third molten salt pipeline 17, the reheater 16 is arranged on the third molten salt pipeline 17, the steam turbine 4 includes a high-pressure cylinder and an intermediate-pressure cylinder, the outlet of the superheater 13 is connected to the inlet of the high-pressure cylinder through the thermal power main steam pipeline 18, the outlet of the high-pressure cylinder is connected to the inlet of the reheater 16 through the thermal power cold section pipeline 19, and the outlet of the reheater 16 is connected to the inlet of the intermediate-pressure cylinder through the thermal power hot section pipeline 20;

[0034] The heat exchange component is used to heat the water supply of the water supply pipe 3 with the molten salt heat of the molten salt component to generate steam, including:

[0035] The exhaust steam of the high-pressure cylinder is reheated by the reheater 16 so that the generated steam enters the medium-pressure cylinder through the thermal power heating section pipeline 20.

[0036] In addition, an embodiment of the present invention also provides a molten salt-based generator set, which is applied to the method mentioned in any of the above embodiments, including a nuclear island steam generator 1, a steam molten salt heat exchanger 2, a molten salt component, a heat exchange component, a water supply pipe 3, a steam turbine 4 and a generator 5. The steam molten salt heat exchanger 2 is respectively connected to the nuclear island steam generator 1 and the molten salt component, and is used to store the steam heat of the nuclear island steam generator 1 in the molten salt of the molten salt component. The heat exchange component is respectively connected to the molten salt component and the water supply pipe 3. The steam turbine 4 is connected to the heat exchange component via a steam pipe, and the steam turbine 4 is connected to the generator 5.

[0037] In one embodiment of the present invention, the inlet of the third molten salt pipeline 17 is disposed at the inlet of the superheater 13 , and the outlet of the third molten salt pipeline 17 is disposed between the superheater 13 and the evaporator 14 .

[0038] In one embodiment of the present invention, it also includes a steam extraction feed water heat exchanger 21, one end of the steam extraction feed water heat exchanger 21 is connected to the high-pressure cylinder through a steam extraction pipeline 22, and the other end is connected to the feed water pipeline 3, and a thermal power feed water pump 23 is provided on the feed water pipeline 3.

[0039] In one embodiment of the present invention, a drain feed water heat exchanger 24 is also provided on the water feed pipe 3, and the drain feed water heat exchanger 24 is respectively connected to the steam molten salt heat exchanger 2 and the nuclear island steam generator 1 through pipes, and a nuclear island feed water pump 25 is provided on the pipe between the drain feed water heat exchanger 24 and the nuclear island steam generator 1.

[0040] The process and purpose of the above technical solution are introduced below.

[0041] 1) Process of heating molten salt with steam in nuclear island

[0042] The high-temperature steam at the outlet of the nuclear island steam generator 1 enters the steam molten salt heat exchanger 2 to heat the molten salt and then turns into drainage; a drainage feed water heat exchanger 24 is set downstream of the feed water of the original thermal power extraction steam feed water heat exchanger 21. The drainage at the outlet of the steam molten salt heat exchanger 3 enters the drainage feed water heat exchanger 24 to heat the feed water, cools to a certain temperature, and is pressurized by the nuclear island feed water pump 25 to enter the nuclear island steam generator 1. The low-temperature molten salt in the cold salt tank 8 enters the steam molten salt heat exchanger 2 after being pressurized by the cold salt pump 9, and is heated by the high-temperature steam of the nuclear island. The molten salt at the outlet of the steam molten salt heat exchanger 2 enters the molten salt electric heater 12 to continue to be heated to a specified temperature and then enters the hot salt tank 6.

[0043] In this process, the nuclear island reactor technology adopts a high temperature gas-cooled reactor, and the outlet of the nuclear island steam generator 1 is high temperature and high pressure steam. High pressure steam corresponds to a higher steam saturation temperature. Under the condition that the inlet molten salt temperature of the steam molten salt heat exchanger 2 is higher than the freezing point and not solidified, the latent heat of steam can be fully utilized to heat the molten salt and increase the molten salt temperature at the heat exchanger outlet. Considering the anti-condensation problem of the low temperature molten salt in the cold salt tank 8, the outlet drain temperature of the steam molten salt heat exchanger 2 is relatively high. A drain feed water heat exchanger 24 is set on the feed water pipeline of the original thermal power unit to fully utilize the drain heat to heat the feed water. While reducing the drain temperature, the feed water temperature entering the preheater 15 can be increased to prevent the outlet molten salt of the preheater 15 from solidifying.

[0044] 2) Molten salt releases heat to generate steam

[0045] The feed water from the feed water pipe 3 at the inlet of the original thermal power unit boiler enters the drain feed water heat exchanger 24 for heating and then enters the steam generation system. It passes through the preheater 15, the evaporator 14, and the superheater 13 in sequence and is heated by the molten salt into high-temperature superheated steam and enters the original thermal power main steam pipe 18. The low-temperature reheated steam from the original thermal power cold section pipe 19 enters the reheater 16 and is heated by the molten salt into high-temperature reheated steam and then enters the original thermal power heating section pipe 20. The high-temperature molten salt in the hot salt tank 6 is pressurized by the hot salt pump 7 and is divided into two paths, one path enters the superheater 13, and the other path enters the reheater 16. The two paths of molten salt are cooled by steam and merged into one path, and enter the evaporator 14 and the preheater 15 in sequence, and are finally cooled into low-temperature molten salt and enter the cold salt tank 8.

[0046] 3) Steam turbine power generation

[0047] The high-temperature and high-pressure main steam generated by the heat release of the molten salt enters the original thermal power main steam pipeline 18, and then enters the high-pressure cylinder to drive the steam turbine to generate electricity. The exhaust steam of the high-pressure cylinder enters the reheater 16 through the original thermal power cold section pipeline 19, and enters the original thermal power hot section pipeline 20 after being heated to high-temperature reheat steam, and then enters the medium-pressure cylinder to drive the steam turbine to generate electricity. The outlet feed water of the original thermal power feed water pump 23 is heated in turn by the extraction steam feed water heat exchanger 21 and the drainage feed water heat exchanger 24 to generate high-temperature and high-pressure steam. When the drainage feed water heat exchanger 24 is put into operation, the extraction steam feed water heat exchanger 21 is completely or partially shut down, which can reduce the steam extraction amount of the steam turbine to increase the power generation of the steam turbine.

[0048] In summary, the above technical solution stores the heat of the steam in the secondary circuit of the nuclear island in molten salt, and increases the temperature of the high-temperature molten salt through the molten salt electric heater 12. The molten salt component and the heat exchange component can heat the feed water and low-temperature reheat steam of the original thermal power unit, and generate the main steam and high-temperature reheat steam with the same parameters as the original thermal power unit, which solves the problem that the parameters of the main steam system and reheat steam system of the nuclear power unit do not match those of the thermal power unit during the nuclear power transformation of the thermal power unit. Through this reasonable transformation method for nuclear power transformation of the thermal power unit, the steam turbine power generation system of the original thermal power unit can be maintained unchanged, the existing assets are used to the maximum extent, and the transformation investment is reduced.

[0049] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical factors in the process, method, article or device including the elements.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for replacing thermal power with nuclear power based on molten salt, characterized in that: include: The steam heat of the nuclear island steam generator (1) is stored in the molten salt of the molten salt assembly by using a steam molten salt heat exchanger (2); Using the heat exchange component to heat the feed water of the water supply pipe (3) with the heat of the molten salt of the molten salt component to generate steam, so that the steam drives the steam turbine (4) to work; Based on the temperature and flow of the molten salt in the molten salt assembly and the pressure and flow of the feed water in the feed water pipeline (3), the parameters of the steam supplied to the steam turbine are controlled to achieve thermal system matching between the nuclear power reactor and the thermal power unit.

2. The method according to claim 1, characterized in that The molten salt assembly comprises a hot salt tank (6), a hot salt pump (7), a cold salt tank (8) and a cold salt pump (9); the hot salt tank (6) and the cold salt tank (8) are connected via a first molten salt pipeline (10) and a second molten salt pipeline (11); The method of using a steam molten salt heat exchanger (2) to store the steam heat of a nuclear island steam generator (1) in molten salt of a molten salt assembly comprises: The cold salt pump (9) is used to supply the cold molten salt in the cold salt tank (8) to the hot salt tank (6) through the first molten salt pipeline (10); wherein the cold molten salt absorbs the steam heat of the nuclear island steam generator (1) while passing through the first molten salt pipeline (10).

3. The method according to claim 2, characterized in that The molten salt assembly further comprises a molten salt electric heater (12), wherein the molten salt electric heater (12) is arranged on the first molten salt pipeline (10) and is located between the steam molten salt heat exchanger (2) and the hot salt tank (6); Also includes: The molten salt electric heater (12) is used to further heat the molten salt flowing out of the steam molten salt heat exchanger (2).

4. The method according to claim 3, characterized in that The heat exchange component comprises a superheater (13), an evaporator (14) and a preheater (15) which are sequentially arranged along the flow direction of the hot molten salt, and the preheater (15), the evaporator (14) and the superheater (13) are sequentially arranged along the flow direction of the feed water, and the outlet of the superheater (13) is connected to the steam turbine (4); The method of using the heat exchange component to heat the feed water of the water supply pipe (3) with the heat of the molten salt of the molten salt component to generate steam comprises: The preheater (15), the evaporator (14) and the superheater (13) are used to heat the feed water in the feed water pipeline (3) in sequence to generate superheated steam.

5. The method according to claim 4, characterized in that The heat exchange component further comprises a reheater (16); the second molten salt pipeline (11) is further connected in parallel with a third molten salt pipeline (17); the reheater (16) is arranged on the third molten salt pipeline (17); the steam turbine (4) comprises a high-pressure cylinder and an intermediate-pressure cylinder; the outlet of the superheater (13) is connected to the inlet of the high-pressure cylinder via a thermal power main steam pipeline (18); the outlet of the high-pressure cylinder is connected to the inlet of the reheater (16) via a thermal power cold section pipeline (19); and the outlet of the reheater (16) is connected to the inlet of the intermediate-pressure cylinder via a thermal power hot section pipeline (20); The method of using the heat exchange component to heat the feed water of the water supply pipe (3) with the heat of the molten salt of the molten salt component to generate steam comprises: The reheater (16) is used to reheat the exhaust steam of the high-pressure cylinder, so that the generated steam enters the medium-pressure cylinder through the thermal power heating section pipeline (20).

6. A molten salt-based generator set, characterized in that: The method applied to claim 5 comprises a nuclear island steam generator (1), a steam molten salt heat exchanger (2), a molten salt component, a heat exchange component, a water supply pipe (3), a steam turbine (4) and a generator (5), wherein the steam molten salt heat exchanger (2) is respectively connected to the nuclear island steam generator (1) and the molten salt component, and is used to store the steam heat of the nuclear island steam generator (1) in the molten salt of the molten salt component, the heat exchange component is respectively connected to the molten salt component and the water supply pipe (3), the steam turbine (4) is connected to the heat exchange component via a steam pipe, and the steam turbine (4) is connected to the generator (5).

7. The generator set according to claim 6, characterized in that: The inlet of the third molten salt pipeline (17) is arranged at the inlet of the superheater (13), and the outlet of the third molten salt pipeline (17) is arranged between the superheater (13) and the evaporator (14).

8. The generator set according to claim 6, characterized in that: It also includes a steam extraction feed water heat exchanger (21), one end of which is connected to the high-pressure cylinder via a steam extraction pipeline (22), and the other end of which is connected to the feed water pipeline (3), and a thermal power feed water pump (23) is provided on the feed water pipeline (3).

9. The generator set according to claim 8, characterized in that: A drain feed water heat exchanger (24) is also provided on the water supply pipeline (3), and the drain feed water heat exchanger (24) is connected to the steam molten salt heat exchanger (2) and the nuclear island steam generator (1) through pipelines, respectively. A nuclear island feed water pump (25) is provided on the pipeline between the drain feed water heat exchanger (24) and the nuclear island steam generator (1).

Images