Device and method for starting preheating of molten salt heat release system coupled with coal-fired power generation

Abstract

The present invention discloses a device and method for starting and preheating a molten salt heat release system coupled with coal-fired power generation. The device includes a low-temperature molten salt tank (1), a high-temperature molten salt tank (9), a molten salt-water preheater (11), a molten salt-steam water evaporator (12), and a molten salt-steam superheater (13), and a water-side start-up preheating circuit, a molten salt-side start-up preheating circuit, and a steam-side start-up preheating circuit are provided. The water-side start-up preheating circuit includes a normal-temperature water circuit, a high-temperature water circuit, and a start-up circulation pump (15). The water side of the molten salt-steam water evaporator (12) is connected to the inlet of the start-up circulation pump (15). The outlet of the start-up circulation pump (15) is divided into two paths. The first path leads to the original unit water purification room, and the second path is connected to the water-side inlet of the molten salt-water preheater (11). The device and method are economical, flexible, and convenient to control, and can better adapt to the rapid start-up of the molten salt heat release system of the coupled coal-fired unit, meeting the requirements for the flexibility of the coal-fired unit.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and in particular to a device for starting and preheating a molten salt heat release system for coupling coal-fired power generation. The present invention also relates to a method for starting and preheating a molten salt heat release system for coupling coal-fired power generation. Background Art

[0002] Currently, increasing the installed capacity and power generation proportion of renewable energy is the main development trend in the energy industry. However, power generation methods such as wind power, solar thermal power, and photovoltaic power generally have intermittency, volatility, and unpredictability. Increasing the access scale of renewable energy poses challenges to the safe operation of the power grid. Using coal resources to make up for the reduction in power grid stability caused by the grid connection of renewable energy and giving full play to the "ballast" role of coal resources, coal-fired power generation units need to undertake important peak shaving tasks for a long time in the future.

[0003] Among many energy storage technologies, molten salt is widely used in medium- and high-temperature heat storage due to its low vapor pressure, high heat capacity, low viscosity, etc. The excess heat energy in the low-load section of a coal-fired power plant is stored and released when needed to solve the problems caused by the mismatch between heat energy supply and demand in terms of time, space, or intensity.

[0004] Adding a molten salt system to a traditional coal-fired power station is beneficial to the flexible and efficient utilization of boiler heat, improving its economy and flexibility. Among them, the heat release system should be able to start quickly to meet the requirements of rapid load increase. During the high-load heat release stage, the steam generated by the molten salt heat release system and the steam generated by the coal-fired boiler jointly enter the steam turbine to do work, greatly improving the load increase rate of the unit.

[0005] The molten salt heat release system in solar thermal power generation mostly operates under stable conditions and does not have the ability of flexible adjustment. However, the molten salt heat release system for coupling coal-fired power generation shoulders the task of rapid load increase and needs to have the function of rapid start-up.

[0006] The heat storage and release system generally uses binary salts (60% NaNO 3 + 40% KNO 3 ) or ternary salts (53% KNO 3 + 40 NaNO 2 + 7% NaNO 3)As media, both of these two salts have a relatively high specific heat. The melting point of the binary salt is 220 °C and the decomposition temperature is 585 °C; the melting point of the ternary salt is 142 °C and the decomposition temperature is 450 °C. Since the freezing point temperature of the molten salt is relatively high, a special preheating device needs to be set up. During the heat release process, if the hot molten salt is directly heat-exchanged with the feed water of the molten salt system, there will be a large temperature difference. In addition, to meet the requirement of rapid load increase, the rapid injection of the high-temperature salt will inevitably cause a large thermal stress impact on the heat exchange equipment and pipelines, threatening the safety of the equipment, and there is also a risk of molten salt solidification.

[0007] At present, the thermal insulation technology for molten salt tanks, pipelines, etc. during the operation of the molten salt system is relatively mature, while there is less research on the first startup of the molten salt heat release system. The main solution is to set an electric heater as the heat source on the main pipeline of the feed water of the molten salt-water preheater, and synchronously preheat equipment and pipelines such as the evaporator and superheater by heating the feed water to generate saturated steam. During this process, the power of the electric heating should not be selected too large, otherwise the steam preheating will be very slow; secondly, when rapidly increasing the load, the power grid has a large demand for power generation, and it is not suitable to use electric heating for startup preheating; finally, only preheating the steam-water side pipelines while ignoring the preheating of the molten salt side equipment and pipelines will also cause thermal stress impact during the rapid load increase process, affecting the equipment life and safety.

[0008] In this regard, CN207454042 U discloses a molten salt steam generation system for solar thermal power generation. This preheating method directly mixes hot water and cold water and then inputs them into the preheater and evaporator. Since it is mixed first and then directly enters the preheater and evaporator, the phenomenon of thermal stress impact on the water side still exists, and a low-load heater needs to be added.

[0009] CN204042829 U discloses a high-temperature molten salt steam generation and preheating system. Its preheating method for the salt side and steam side is to mix hot salt and cold salt in a mixer and then directly input them into the superheater, evaporator and preheater. Similarly, since it is mixed first and then directly enters the superheater, evaporator and preheater, the phenomenon of thermal stress impact on the salt side still exists. Summary of the Invention

[0010] The purpose of the present invention is to provide a device and method for starting and preheating a molten salt heat release system coupled with coal-fired power generation to solve the above technical problems.

[0011] To achieve the above purpose, the present invention provides a device for starting and preheating a molten salt heat release system coupled with coal-fired power generation, including a low-temperature molten salt tank, a high-temperature molten salt tank, a molten salt-water preheater, a molten salt-steam-water evaporator, and a molten salt-steam superheater, and is provided with a water-side starting preheating circuit, a molten salt-side starting preheating circuit, and a steam-side starting preheating circuit;

[0012] The water-side start-up preheating circuit includes a normal-temperature water circuit, a high-temperature water circuit, and a start-up circulation pump. The normal-temperature water circuit is provided with a normal-temperature water supply pump and a first control valve. The high-temperature water circuit is provided with a molten salt system water supply pump and a second control valve. The normal-temperature water circuit and the high-temperature water circuit are connected in parallel and are connected to the water-side inlet of the molten salt-water preheater. The water side of the molten salt-steam evaporator is connected to the inlet of the start-up circulation pump. The outlet of the start-up circulation pump is divided into two paths. The first path leads to the original unit's water purification room and is provided with a third control valve. The second path is connected to the water-side inlet of the molten salt-water preheater.

[0013] The molten salt-side start-up preheating circuit includes a molten salt temperature regulating pump and a high-temperature molten salt pump. The high-temperature molten salt tank is connected to the inlet of the molten salt-steam superheater through the high-temperature molten salt pump and a fifth control valve. The outlet of the low-temperature molten salt tank is connected to the inlet of the molten salt temperature regulating pump. The outlet of the molten salt temperature regulating pump is divided into two paths. One path is connected to the inlet of the molten salt-steam superheater through an eighth control valve, and the other path is connected to the inlet of the molten salt-steam evaporator through a seventh control valve.

[0014] The steam-side start-up preheating circuit includes a steam source from the original unit. The steam source is connected to the steam-side inlet of the molten salt-steam evaporator through a fourth control valve.

[0015] Optionally, the inlet of the normal-temperature water supply pump is connected to a normal-temperature water source, and the first control valve is arranged on the outlet pipeline of the normal-temperature water supply pump.

[0016] Optionally, the inlet of the molten salt system water supply pump is connected to the outlet of the second control valve, and the inlet of the second control valve is connected to a high-temperature water source.

[0017] Optionally, a sixth control valve is arranged on the outlet pipeline of the molten salt temperature regulating pump.

[0018] Optionally, electric tracing equipment is provided on the low-temperature molten salt tank, high-temperature molten salt tank, and molten salt pipeline.

[0019] Optionally, a high-temperature molten salt circuit is arranged between the outlet of the high-temperature molten salt pump and the high-temperature molten salt tank, and a ninth control valve is arranged on the high-temperature molten salt circuit.

[0020] Optionally, a low-temperature molten salt circuit is arranged between the outlet of the molten salt temperature regulating pump and the low-temperature molten salt tank, and a tenth control valve is arranged on the low-temperature molten salt circuit.

[0021] Optionally, an eleventh control valve is arranged on the pipeline connecting the molten salt system water supply pump and the molten salt-water preheater. The outlet of the start-up circulation pump is connected downstream of the eleventh control valve, and the outlet of the first control valve is connected upstream of the eleventh control valve.

[0022] Optionally, a high-temperature water circuit is provided between the molten salt system feed pump and the high-temperature water source, and a twelfth control valve is provided on the high-temperature water circuit.

[0023] Optionally, a bypass is provided at the steam outlet of the molten salt-steam superheater, and a molten salt steam pre-storage tank is connected to the bypass.

[0024] To achieve the above object, the present invention provides a method for starting and preheating a molten salt heat release system coupled with coal-fired power generation, which is used to control the device for starting and preheating the molten salt heat release system coupled with coal-fired power generation described in any one of the above. The preheating of the water-side starting preheating circuit includes a normal-temperature water stage, a water mixing stage, and a high-temperature water replacement stage:

[0025] In the normal-temperature water stage, start the normal-temperature feed pump and the circulation pump, open the first control valve, close the molten salt system feed pump, the second control valve, and the third control valve. Under the action of the start circulation pump (15), circulate the normal-temperature water on the water side of the molten salt-water preheater and the molten salt-steam-water evaporator until the water-side pipeline and equipment are filled with normal-temperature water;

[0026] In the water mixing stage, start the molten salt system feed pump, open the third control valve, close the first control valve and the normal-temperature feed pump, and gradually open the second control valve to gradually mix the hot water from the high-temperature water circuit with the normal-temperature water in the water-side pipeline and equipment;

[0027] In the high-temperature water replacement stage, under the action of the start circulation pump, replace the mixed water in the water-side pipeline and equipment with hot water to complete the water-side preheating.

[0028] Further, after the water-side preheating is completed, start the molten salt-side start preheating and the steam-side start preheating. The molten salt-side start preheating includes a cold salt heating stage, a molten salt mixing stage, and a hot salt replacement stage:

[0029] In the cold salt heating stage, open the molten salt temperature regulating pump, the seventh control valve, and the eighth control valve, close the high-temperature molten salt pump and the fifth control valve, inject the cold salt from the low-temperature molten salt tank into the molten salt-side channels of the molten salt-steam superheater, the molten salt-steam-water evaporator, and the molten salt-water preheater. During this process, open the fourth control valve to preheat the steam side of the molten salt-steam-water evaporator, the molten salt-steam superheater, and the connecting pipeline with the steam generated by heating the cold salt to the water and the steam from the original unit;

[0030] In the molten salt mixing stage, gradually close the seventh control valve and the eighth control valve, open the high-temperature molten salt pump, and gradually open the fifth control valve to gradually mix the cold salt in the molten salt-side channels of the molten salt-steam superheater, the molten salt-steam-water evaporator, and the molten salt-water preheater with the high-temperature molten salt;

[0031] During the hot salt replacement stage, turn off the molten salt temperature regulating pump, the seventh control valve, and the eighth control valve, and replace the mixed molten salt in the molten salt side channels of the molten salt-steam superheater, the molten salt-steam water evaporator, and the molten salt-water preheater with high-temperature molten salt to complete the preheating of the molten salt side and the steam side.

[0032] The device and method for starting and preheating the molten salt heat release system coupled with coal-fired power generation provided by the present invention preheat the water side water circuit of the molten salt system heat release side by sequentially introducing the normal temperature water and hot water of the original unit in the order of normal temperature water → mixing → high-temperature water. Compared with the method of directly introducing mixed water, it can greatly alleviate the thermal stress impact on the water side water circuit of the molten salt system. Moreover, it reduces the setting of electric heaters on the feed water circuit in traditional preheating, reduces equipment investment and plant electricity consumption. At the same time, by using the existing hot water source of the original coal-fired unit, it avoids the energy loss caused by additional heat source heating; for the preheating of the molten salt side of the molten salt heat release system, low-temperature molten salt and high-temperature molten salt are sequentially introduced in the order of low-temperature molten salt → mixed molten salt → high-temperature molten salt. Compared with the method of directly introducing mixed molten salt, it can greatly alleviate the thermal stress impact on the salt road of the molten salt system heat release side. Moreover, the steam generated by preheating the molten salt side and the steam of the original unit can be jointly used to preheat the steam equipment and pipelines on the heat release side of the molten salt system. Through control, it can effectively ensure the safety of the preheating process of the molten salt side and the steam-water side of the molten salt system, as well as the flexible switching of the operating mode of the molten salt heat release system, reduce the start-up preheating time of the molten salt heat release system, and improve the flexibility of the unit. It has the advantages of simple system, good economy, easy implementation, and perfect and reasonable control method, and can be widely used in the start-up preheating process of the molten salt heat release system coupled with coal-fired power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the device for starting and preheating the molten salt heat release system coupled with coal-fired power generation provided by the embodiment of the present invention;

[0034] Figure 2 It is a schematic flow path diagram when the preheating of the water side start-up preheating circuit is in the normal temperature water stage;

[0035] Figure 3 It is a schematic flow path diagram when the preheating of the water side start-up preheating circuit is in the water mixing stage;

[0036] Figure 4 It is a schematic flow path diagram when the preheating of the water side start-up preheating circuit is in the high-temperature water replacement stage;

[0037] Figure 5 It is a schematic flow path diagram when the molten salt side start-up preheating is in the cold salt heating stage;

[0038] Figure 6 It is a schematic flow path diagram when the molten salt side start-up preheating is in the molten salt mixing stage;

[0039] Figure 7 It is a schematic diagram of the flow path when the molten salt side starts preheating and is in the hot salt replacement stage.

[0040] In the figure:

[0041] 1. Low-temperature molten salt tank 2. Molten salt temperature regulating pump 3. Sixth control valve 4. Tenth control valve 5. Seventh control valve 6. Eighth control valve 7. Fifth control valve 8. Ninth control valve 9. High-temperature molten salt tank 10. High-temperature molten salt pump 11. Molten salt-water preheater 12. Molten salt-steam water evaporator 13. Molten salt-steam superheater 14. Molten salt steam pre-storage tank 15. Start-up circulation pump 16. Molten salt system feed pump 17. High-temperature water source 18. First control valve 19. Second control valve 20. Twelfth control valve 21. Third control valve 22. Fourth control valve 23. Eleventh control valve 24. Normal temperature feed pump 25. Normal temperature water source 26. Steam inlet position. Specific embodiments

[0042] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0043] In this article, terms such as "upper, lower, inner, outer" are established based on the positional relationship shown in the drawings. Depending on the different drawings, the corresponding positional relationship may also change accordingly. Therefore, it cannot be understood as an absolute limitation of the protection scope; moreover, relational terms such as "first" and "second" are only used to distinguish one component with the same name from another, and do not necessarily require or imply any such actual relationship or order between these components.

[0044] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of the device for starting and preheating the molten salt heat release system coupled with coal-fired power generation provided by the embodiment of the present invention.

[0045] As shown in the figure, in a specific embodiment, the device for starting and preheating the molten salt heat release system coupled with coal-fired power generation provided by the present invention mainly consists of a normal temperature water source 25, a high-temperature water source 17, a steam source of a coal-fired unit and a molten salt heat release system disposed thereon. The molten salt heat release system further consists of a low-temperature molten salt tank 1, a molten salt temperature regulating pump 2, a high-temperature molten salt tank 9, a high-temperature molten salt pump 10, a molten salt-water preheater 11, a molten salt-steam water evaporator 12, a molten salt-steam superheater 13, a superheated steam pre-storage tank 14, a molten salt system feed pump 16, a normal temperature feed pump 24, etc.

[0046] In the molten salt exothermic system, the outlet of the low-temperature molten salt tank 1 is connected to the inlet of the molten salt temperature regulating pump 2 through a molten salt pipeline, and the outlet of the molten salt temperature regulating pump 2 is connected to the molten salt side inlet of the molten salt-steam water evaporator 12. The outlet of the high-temperature molten salt tank 9 is connected to the inlet of the high-temperature molten salt pump 10 through a molten salt pipeline, and the outlet of the high-temperature molten salt pump 10 is connected to the molten salt side inlet of the molten salt-steam superheater 13.

[0047] The normal temperature water source 25 and the high-temperature water source 17 are connected to the water side inlet of the molten salt-water preheater 11, and the steam source from the original unit is connected to the steam side of the molten salt-steam water evaporator 12.

[0048] In order to preheat the entire system, a water side start-up preheating circuit, a molten salt side start-up preheating circuit, and a steam side start-up preheating circuit are formed. The three preheating circuits are interconnected through different interfaces and integrated into a complete preheating device.

[0049] The first preheating circuit, i.e., the water side start-up preheating circuit, includes: the normal temperature water pipeline from the original unit, the normal temperature water source 25, the first control valve 18, the normal temperature feed water pump 24, the high-temperature water source 17, the second control valve 19, the molten salt system feed water pump 16, the eleventh control valve 23, the twelfth control valve 20, the third control valve 21, the start-up circulation pump 15, the molten salt-water preheater 11, and the molten salt-steam water evaporator 12.

[0050] Specifically, a normal temperature feed water pump 24 and a first control valve 18 are arranged on the pipeline where the normal temperature water source 25 is connected to the water side inlet of the molten salt-water preheater 11, thus forming a normal temperature water path; a second control valve 19 and a molten salt system feed water pump 16 are arranged on the pipeline where the high-temperature water source 17 is connected to the water side inlet of the molten salt-water preheater 11, thus forming a high-temperature water path. The normal temperature water path and the high-temperature water path are in parallel and connected to the water side inlet of the molten salt-water preheater 11.

[0051] The water side of the molten salt-steam water evaporator 12 is connected to the water side inlet of the molten salt-water preheater 11 through a pipeline and a start-up circulation pump 15. The outlet of the start-up circulation pump 15 is divided into two paths. One path is connected to the water side inlet of the molten salt-water preheater 11, and the other path is connected to the water purification room of the original unit and a third control valve 21 is arranged on the pipeline.

[0052] A fourth control valve 22 is arranged on the pipeline where the steam side of the molten salt-steam water evaporator 12 is connected to the steam source of the original unit.

[0053] An eleventh control valve 12 is arranged on the pipeline where the molten salt system feed water pump 16 is connected to the molten salt-water preheater 11. The outlet of the start-up circulation pump 15 is connected to the downstream of the eleventh control valve 12 through a pipeline, and the outlet of the first control valve 18 is connected to the upstream of the eleventh control valve 12.

[0054] A high-temperature water circuit is provided between the molten salt system feed pump 16 and the high-temperature water source 17, and a twelfth control valve 20 is provided on the high-temperature water circuit.

[0055] The normal-temperature water source from the original unit can draw water from a position with appropriate water quality and temperature in the unit, such as the condenser, etc.

[0056] The water temperature of the high-temperature water source from the original unit is greater than the molten salt solidification temperature, and the deaerator, high / low-pressure heaters, etc. can be selected according to the temperature matching principle.

[0057] The second preheating circuit, that is, the molten salt side start-up preheating circuit includes: a low-temperature molten salt tank 1, a molten salt temperature regulating pump 2, a sixth control valve 3, a tenth control valve 4, a seventh control valve 5, an eighth control valve 6, a fifth control valve 7, a high-temperature molten salt tank 9, a high-temperature molten salt pump 10, a ninth control valve 8, a molten salt steam pre-storage device 14, a molten salt-steam superheater 13, a molten salt-steam water evaporator 12, and a molten salt-water preheater 11.

[0058] Specifically, a fifth control valve 7 is provided on the outlet pipeline of the high-temperature molten salt pump 10, and a sixth control valve 3 is arranged on the outlet pipeline of the molten salt temperature regulating pump 2. After the sixth control valve 3, it is divided into two paths. One path is connected to the molten salt side inlet of the molten salt-steam water evaporator 12 through the seventh control valve 5, and the other path is connected to the molten salt side inlet of the molten salt-steam superheater 13 through the eighth control valve 6.

[0059] A high-temperature molten salt circuit is provided between the outlet of the high-temperature molten salt pump 10 and the high-temperature molten salt tank 9, and a ninth control valve 8 is provided on the high-temperature molten salt circuit.

[0060] A low-temperature molten salt circuit is provided between the outlet of the molten salt temperature regulating pump 2 and the low-temperature molten salt tank 1, and a tenth control valve 4 is provided on the low-temperature molten salt circuit.

[0061] The third preheating circuit, that is, the steam side start-up preheating circuit includes: a steam source from the original unit and a fourth control valve 22, and the steam source is connected to the steam side inlet of the molten salt-steam water evaporator 12 through the fourth control valve 22.

[0062] The steam outlet of the molten salt-steam superheater 13 leads to the steam merging position 26. The steam generated during the preheating process can enter the steam system of the original coal-fired unit according to the parameter matching principle, including but not limited to the bypass of the low-pressure heater of the steam turbine, the deaerator, and the auxiliary steam header, etc. The pipeline leading to the steam merging position 26 is connected with a molten salt steam pre-storage device 14 through a bypass.

[0063] The outlet of the molten salt steam pre-storage device 14 is connected to the bypass of the low-pressure heater of the steam turbine, the deaerator, or the auxiliary steam header, etc., and at the same time, the steam side start-up preheating of the molten salt heat release system is jointly realized by means of the steam generated by the salt side preheating.

[0064] The steam source from the original unit is selected from the positions such as extraction steam, auxiliary steam, high / low-pressure heaters, and deaerators according to the principle of temperature matching.

[0065] The present invention also provides a method for starting and preheating a molten salt heat release system coupled with coal-fired power generation, which is used to control the device for starting and preheating the molten salt heat release system coupled with coal-fired power generation described above. The preheating of the water-side starting preheating circuit includes a normal-temperature water stage, a water mixing stage, and a high-temperature water replacement stage:

[0066] S11: In the normal-temperature water stage, start the normal-temperature feed water pump 24 and the start-up circulation pump 15, open the first control valve 18, close the molten salt system feed water pump 16, the second control valve 19, and the third control valve 21. Draw normal-temperature water from the normal-temperature water source 25 of the original unit into the molten salt-water preheater 11. Under the action of the start-up circulation pump (15), circulate the normal-temperature water on the water side of the molten salt-water preheater 11 and the molten salt-steam-water evaporator 12 until the water-side pipelines and equipment are filled with normal-temperature water (see the dotted line part in Figure 2 .

[0067] S12: In the water mixing stage, start the molten salt system feed water pump 16, open the third control valve 21, close the first control valve 18 and the normal-temperature feed water pump 24, and gradually open the second control valve 19 to gradually mix the hot water from the high-temperature water source 17 with the normal-temperature water in the water-side pipelines and equipment to a set temperature value, and displace the normal-temperature water to the water purification room of the original unit (see the double-dotted line and dot line part in Figure 3 .

[0068] S13: In the high-temperature water replacement stage, under the action of the start-up circulation pump 15, the mixed water is output to the water purification room of the original unit, and the mixed water in the water-side pipelines and equipment is replaced with high-temperature water to realize the water-side preheating of the molten salt-steam-water evaporator 12 and the molten salt-water preheater 11 (see the dot line part in Figure 4 .

[0069] After the water-side preheating is completed, start the molten salt-side start-up preheating and the steam-side start-up preheating. The molten salt-side start-up preheating includes a cold salt heating stage, a molten salt mixing stage, and a hot salt replacement stage:

[0070] S21: In the cold salt heating stage, open the molten salt temperature regulating pump 2, the seventh control valve 5, and the eighth control valve 6, close the high-temperature molten salt pump 10 and the fifth control valve 7, and inject the cold salt in the low-temperature molten salt tank 1 into the molten salt-side channels of the molten salt-steam superheater 13, the molten salt-steam-water evaporator 12, and the molten salt-water preheater 11 to fill the molten salt pipelines with low-temperature molten salt.

[0071] During this process, the fourth control valve 22 is opened to allow the steam from the original unit to enter the steam side of the molten salt - steam water evaporator 12, the molten salt - steam superheater 13 and the connecting pipelines. Together with the steam generated by flashing during the preheating process and the steam generated by heating the feed water of the molten salt heat release system with low - temperature molten salt, they are transported to the steam merging position 26 to jointly preheat the steam - side containers and pipelines of the molten salt system (see Figure 5 the dashed and dotted - line parts).

[0072] S22: In the molten salt blending stage, gradually close the seventh control valve 5 and the eighth control valve 6, start the high - temperature molten salt pump 10, and gradually open the fifth control valve 7 to gradually blend the cold salt in the molten salt - side channels of the molten salt - steam superheater 13, the molten salt - steam water evaporator 12 and the molten salt - water preheater 11 with the high - temperature molten salt to the set temperature value, and replace the cold salt in the molten salt - side channels with the blended molten salt (see Figure 6 the dashed, double - dotted - line and dotted - line parts).

[0073] S32: In the hot salt replacement stage, completely close the molten salt temperature - regulating pump 2, the seventh control valve 5 and the eighth control valve 6, and replace the blended molten salt in the molten salt - side channels of the molten salt - steam superheater 13, the molten salt - steam water evaporator 23 and the molten salt - water preheater 11 with high - temperature molten salt to complete the preheating of the molten salt side and the steam side (see Figure 7 the dotted - line part).

[0074] The above - mentioned embodiments are only the preferred solutions of the present invention, and are not specifically limited thereto. On this basis, targeted adjustments can be made according to actual needs to obtain different implementation manners. For example, electric tracing equipment is provided on the low - temperature molten salt tank 1, the high - temperature molten salt tank 9 and the molten salt pipelines, etc. Since there are many possible implementation manners, they will not be listed one by one here.

[0075] The device and method are economical, flexible and easy to control, and can better adapt to the rapid start - up of the molten salt heat release system of the coupled coal - fired unit, meeting the requirements for the flexibility of coal - fired units under the background of carbon peak and carbon neutrality.

[0076] The above - mentioned device and method for starting and preheating the molten salt heat release system for coupled coal - fired power generation of the present invention have been introduced in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above - mentioned embodiments is only used to help understand the core idea of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A device for starting and preheating a molten salt heat release system coupled with coal-fired power generation, comprising a low-temperature molten salt tank (1), a high-temperature molten salt tank (9), a molten salt-water preheater (11), a molten salt-steam evaporator (12), and a molten salt-steam superheater (13), characterized in that: A water side start-up preheating circuit, a molten salt side start-up preheating circuit and a steam side start-up preheating circuit are provided; The water-side starting preheating circuit comprises a normal temperature water circuit, a high temperature water circuit and a starting circulation pump (15); the normal temperature water circuit is provided with a normal temperature water supply pump (24) and a first control valve (18); the high temperature water circuit is provided with a molten salt system water supply pump (16) and a second control valve (19); the normal temperature water circuit is connected in parallel with the high temperature water circuit and is connected to the water side inlet of the molten salt-water preheater (11); the water side of the molten salt-steam-water evaporator (12) is connected to the inlet of the starting circulation pump (15); the outlet of the starting circulation pump (15) is divided into two paths, the first path leads to the water purification room of the original unit and is provided with a third control valve (21), and the second path is connected to the water side inlet of the molten salt-water preheater (11); The molten salt side startup preheating circuit comprises a molten salt temperature regulating pump (2) and a high-temperature molten salt pump (10); the high-temperature molten salt tank (9) is connected to the inlet of the molten salt-steam superheater (13) via the high-temperature molten salt pump (10) and the fifth control valve (7); the outlet of the low-temperature molten salt tank (1) is connected to the inlet of the molten salt temperature regulating pump (2), and the outlet of the molten salt temperature regulating pump (2) is divided into two paths, one of which is connected to the inlet of the molten salt-steam superheater (13) via the eighth control valve (6), and the other of which is connected to the inlet of the molten salt-steam evaporator (12) via the seventh control valve (5); The steam-side startup preheating loop comprises a steam source from the original unit, and the steam source is connected to the steam-side inlet of the molten salt-steam-water evaporator (12) via a fourth control valve (22).

2. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: The inlet of the normal temperature water supply pump (24) is connected to a normal temperature water source (25), and the first control valve (18) is arranged on the outlet pipeline of the normal temperature water supply pump (24).

3. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: The inlet of the molten salt system water supply pump (16) is connected to the outlet of the second control valve (19), and the inlet of the second control valve (19) is connected to the high-temperature water source (17).

4. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: A sixth control valve (3) is arranged on the outlet pipeline of the molten salt temperature regulating pump.

5. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: The low-temperature molten salt tank, the high-temperature molten salt tank and the molten salt pipeline are all provided with electric heating equipment.

6. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: A high-temperature molten salt loop is provided between the outlet of the high-temperature molten salt pump (10) and the high-temperature molten salt tank (9), and a ninth control valve (8) is provided on the high-temperature molten salt loop.

7. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: A low-temperature molten salt loop is provided between the outlet of the molten salt temperature regulating pump (2) and the low-temperature molten salt tank (1), and a tenth control valve (4) is provided on the low-temperature molten salt loop.

8. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: An eleventh control valve (23) is arranged on the pipeline connecting the molten salt system water supply pump (16) and the molten salt-water preheater (11); the outlet of the starting circulation pump (15) is connected to the downstream of the eleventh control valve (23); and the outlet of the first control valve (18) is connected to the upstream of the eleventh control valve (23).

9. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: A high-temperature water circuit is provided between the molten salt system water supply pump (16) and the high-temperature water source (17), and a twelfth control valve (20) is provided on the high-temperature water circuit.

10. The device for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 1, characterized in that: The steam outlet of the molten salt-steam superheater (13) is provided with a bypass, and the bypass is connected to a molten salt steam pre-storage tank (14).

11. A method for starting and preheating a molten salt heat release system coupled with coal-fired power generation, used to control the device for starting and preheating a molten salt heat release system coupled with coal-fired power generation as claimed in any one of claims 1 to 10, characterized in that: The preheating of the water-side startup preheating circuit includes a normal temperature water stage, a water mixing stage and a high temperature water replacement stage: In the normal temperature water stage, the normal temperature water supply pump (24) and the start-up circulation pump (15) are started, the first control valve (18) is opened, the molten salt system water supply pump (16), the second control valve (19) and the third control valve (21) are closed, and under the action of the start-up circulation pump (15), the normal temperature water is circulated on the water side of the molten salt-water preheater (11) and the molten salt-steam-water evaporator (12) until the water side pipelines and equipment are filled with normal temperature water; In the water mixing stage, the molten salt system water supply pump (16) is started, the third control valve (21) is opened, the first control valve (18) and the normal temperature water supply pump (24) are closed, and the second control valve (19) is gradually opened to gradually mix and replace the hot water from the high temperature water circuit with the normal temperature water in the water side pipeline and equipment; In the high-temperature water replacement stage, the mixed water in the water side pipeline and equipment is replaced with hot water under the action of starting the circulation pump (15), thereby completing the water side preheating.

12. The method for starting and preheating a molten salt heat release system coupled with coal-fired power generation according to claim 11, characterized in that: After the water side preheating is completed, the molten salt side startup preheating and the steam side startup preheating are started. The molten salt side startup preheating includes the cold salt heating stage, the molten salt mixing stage and the hot salt replacement stage: In the cold salt heating stage, the molten salt temperature regulating pump (2), the seventh control valve (5), and the eighth control valve (6) are opened, and the high-temperature molten salt pump (10) and the fifth control valve (7) are closed, and the cold salt in the low-temperature molten salt tank (1) is injected into the molten salt side channels of the molten salt-steam superheater (13), the molten salt-steam-water evaporator (12), and the molten salt-water preheater (11). During this process, the fourth control valve (22) is opened so that the steam generated by the cold salt heating feed water and the steam from the original unit can jointly preheat the steam side of the molten salt-steam-water evaporator (12), the molten salt-steam superheater (13), and the connecting pipelines; In the molten salt mixing stage, the seventh control valve (5) and the eighth control valve (6) are gradually closed, the high-temperature molten salt pump (10) is turned on, and the fifth control valve (7) is gradually opened to gradually mix the cold salt in the molten salt side channels of the molten salt-steam superheater (13), the molten salt-steam-water evaporator (12) and the molten salt-water preheater (11) with the high-temperature molten salt; In the hot salt replacement stage, the molten salt temperature regulating pump (2), the seventh control valve (5), and the eighth control valve (6) are closed, and the mixed molten salt in the molten salt side channels of the molten salt-steam superheater (13), the molten salt-steam-water evaporator (12), and the molten salt-water preheater (11) is replaced with high-temperature molten salt, thereby completing the preheating of the molten salt side and the steam side.

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