Molten salt heat storage and release unit and deep peak regulation system for boiler unit

Abstract

The present application provides a molten salt heat storage and release unit and a deep peak regulation system for a boiler unit, the molten salt heat storage and release unit comprising a molten salt storage assembly, a heat exchange energy storage assembly, and a heat exchange energy release assembly, wherein the molten salt storage assembly comprises a high-temperature molten salt storage tank and a low-temperature molten salt storage tank; the heat exchange energy storage assembly is connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank, and comprises a flue gas heat exchange device and a steam heat exchange device, and molten salt in the low-temperature molten salt storage tank sequentially passes through the flue gas heat exchange device and the steam heat exchange device and then flows into the high-temperature molten salt storage tank; and the heat exchange energy release assembly is connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank, and comprises a pulverized coal heating device and a feedwater heating device, and molten salt in the high-temperature molten salt storage tank releases energy through the pulverized coal heating device and / or the feedwater heating device and then flows into the low-temperature molten salt storage tank. The present application provides a molten salt heat storage and release unit and a deep peak regulation system for a boiler unit with flexible peak regulation and high energy efficiency.

Description

A molten salt thermal energy storage unit and a deep peak regulation system for boiler units

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on February 26, 2024, with application number 202410208386.9 and invention name “A molten salt thermal energy storage and energy release unit and a deep peak-shaving system for a boiler unit”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of boiler peak regulation, and in particular to a molten salt heat storage and energy release unit and a deep peak regulation system for a boiler unit. Background Art

[0004] The unpredictable and discontinuous nature of renewable energy generation leads to unstable power, impacting grid power quality and preventing some renewable energy from entering the grid, resulting in the phenomenon of "wind and solar power curtailment." To address the low penetration of renewable energy into the grid, the current approach to consuming renewable energy electricity primarily relies on peak load regulation, with thermal power units representing a significant portion of the generation capacity. To overcome the slow peak load response and significant hysteresis inherent in traditional thermal power generation, energy storage technologies are being increasingly developed to address the poor peak load regulation performance of thermal power generation.

[0005] Energy storage technology, as a technical means of changing the spatiotemporal distribution of energy, can significantly improve the peak-shaving flexibility of power plants and alleviate the supply-demand balance problem of the power grid. Among the many energy storage methods, molten salt energy storage has the advantages of high energy storage density, long energy storage cycle and low cost, making it one of the most promising peak-shaving methods for thermal power units. By coupling molten salt energy storage, it is possible to maintain medium and high load operation of the boiler while reducing the electrical load output, thereby achieving flexible and rapid peak-shaving of the power plant. However, conventional molten salt energy storage technology can only store and release high-grade energy, with low energy utilization and prone to huge energy waste.

[0006] Summary of the Invention

[0007] This application is based on the inventor's discovery and understanding of the following facts and problems:

[0008] The present application aims to solve one of the technical problems in the related art at least to a certain extent.

[0009] To this end, the embodiments of the present application propose a molten salt thermal energy storage and release unit and a boiler unit deep peak regulation system, which have the advantage of improving energy utilization.

[0010] The molten salt heat storage and energy release unit provided in the embodiment of the present application includes a molten salt storage component, a heat exchange energy storage component and a heat exchange energy release component, the molten salt storage component includes a high-temperature molten salt storage tank and a low-temperature molten salt storage tank; the heat exchange energy storage component is connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank, the heat exchange energy storage component includes a flue gas heat exchange device and a steam heat exchange device, the molten salt located in the low-temperature molten salt storage tank is heated by the flue gas heat exchange device and the steam heat exchange device in sequence and then flows into the high-temperature molten salt storage tank; the heat exchange energy release component is connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank, the heat exchange energy release component includes a coal powder heating device and a water supply heating device, the molten salt located in the high-temperature molten salt storage tank is released by the coal powder heating device and / or the water supply heating device and then flows into the low-temperature molten salt storage tank.

[0011] The molten salt thermal energy storage and release unit according to the embodiments of the present application can effectively utilize multiple energy sources through a flue gas heat exchanger and a steam heat exchanger. It can absorb low-temperature heat sources at lower temperatures and high-temperature heat sources at higher temperatures. Furthermore, the molten salt thermal energy storage and release unit can also achieve temperature-matched, multi-path release based on the required temperatures of different locations, thereby effectively improving the absorption and utilization efficiency of energy or heat. Furthermore, the device can heat pulverized coal through a pulverized coal heating device, effectively improving the combustion stability of the relevant boiler during low-load combustion.

[0012] In some embodiments, the heat exchange and energy storage assembly further includes an electric heating device located between the steam heat exchange device and the high-temperature molten salt storage tank;

[0013] And / or, the steam heat exchange device includes a primary steam heat exchanger and a secondary steam heat exchanger arranged in sequence along the flow direction.

[0014] In some embodiments, a bypass for the circulation of molten salt working medium is further provided outside the electric heating device, and a switch valve is installed on the bypass.

[0015] In some embodiments, the heat exchange energy release component includes a first energy release branch and a second energy release branch, and the molten salt in the high-temperature molten salt storage tank flows into the first energy release branch and / or the second energy release branch, and then merges and flows into the low-temperature molten salt storage tank;

[0016] The pulverized coal heating device is located on the first energy release branch, and the number of the feedwater heating devices is at least two and they are respectively distributed on the first energy release branch and the second energy release branch.

[0017] In some embodiments, the feed water heating device includes a molten salt feed water medium heat exchanger located on the first energy release branch and a molten salt feed water superheater and a molten salt feed water evaporator located on the second energy release branch.

[0018] The molten salt located in the high-temperature molten salt storage tank flows through the first energy release branch in sequence through the pulverized coal heating device and the molten salt feed water medium-temperature heat exchanger, and / or flows through the second energy release branch in sequence through the molten salt feed water superheater and the molten salt feed water evaporator, and then flows into the low-temperature molten salt storage tank.

[0019] In some embodiments, a molten salt feed water low-temperature heat exchanger is further provided on the second energy release branch, the molten salt feed water low-temperature heat exchanger is connected to the boiler unit, and the condensed water is connected to the boiler unit through the molten salt feed water low-temperature heat exchanger.

[0020] In some embodiments, the heat exchange and energy storage assembly further includes a low-temperature molten salt pump, and the molten salt in the low-temperature molten salt storage tank is driven by the low-temperature molten salt pump to flow into the high-temperature molten salt storage tank through the flue gas heat exchange device and the steam heat exchange device;

[0021] And / or, the heat exchange energy release component also includes a high-temperature molten salt pump, and the molten salt in the high-temperature molten salt storage tank flows into the low-temperature molten salt storage tank through the coal powder heating device and the water supply heating device under the drive of the high-temperature molten salt pump.

[0022] The deep peak-shaving system of a boiler unit provided in an embodiment of the present application includes a molten salt heat storage and energy release unit and a boiler circulation unit, wherein the molten salt heat storage and energy release unit is the molten salt heat storage and energy release unit described in any one of the above items; the boiler circulation unit includes a boiler unit, a steam turbine and a condensate recovery component that are interconnected, the boiler unit cooperates with the heat exchange energy storage component and the heat exchange energy release component, the steam turbine cooperates with the heat exchange energy release component, and the condensate recovery component cooperates with the steam turbine and the heat exchange energy storage component.

[0023] According to the deep peak-shaving system of the boiler unit of the embodiment of the present application, the deep peak-shaving system of the boiler unit can effectively improve the flexible operation of the boiler unit under variable load conditions by applying the above-mentioned molten salt heat storage and energy release unit, and at the same time improve the load response efficiency of the power grid when switching from normal period to peak period and low load period, increase the peak-shaving depth of the unit, and have important significance for improving the service level of the power system. In addition, the above-mentioned deep peak-shaving system of the boiler unit also applies the molten salt heat storage and energy release unit to effectively improve the combustion stability of the boiler unit at low load, and at the same time can improve the heat utilization rate by heat exchange when the power grid is in a high load period, realize the cascade utilization of molten salt energy during energy release, and have better heat exchange efficiency than the existing energy storage system, which can help increase the power generation of the steam turbine.

[0024] In some embodiments, the boiler unit includes a steam release component, a smoke exhaust component, and a coal feed component. The steam release component cooperates with the steam heat exchange device in the heat exchange and energy storage component, the smoke exhaust component cooperates with the flue gas heat exchange device, and the coal feed component cooperates with the pulverized coal heating device.

[0025] The steam turbine comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder coaxially arranged in sequence, the steam generated by the boiler unit flows into the steam release assembly and the high-pressure cylinder respectively; at least part of the feedwater heating device is connected to the intermediate-pressure cylinder via a pipeline, and part of the steam in the high-pressure cylinder and at least part of the steam and / or liquid generated by the feedwater heating device flow into the intermediate-pressure cylinder;

[0026] The condensate recovery component includes a steam heater, an air-to-air condenser, a condensate pump, a deaerator and a drive pump group. The number of the steam heaters is at least three. The high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are connected to at least one of the steam heaters. The steam heat exchange device is connected to the deaerator through a pipeline. The steam discharged from the steam heat exchange device flows into the deaerator through a pipeline. Under the drive of the drive pump group, the condensate generated at the air-to-air condenser and the condensate pump flows through the steam heater and the deaerator in sequence, and flows back to the boiler unit.

[0027] In some embodiments, the driving pump group is provided with at least one drain outlet, and the drain outlet is connected to the water inlet of the water heating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] FIG1 is a schematic structural diagram of a molten salt thermal energy storage unit provided in an embodiment of the present application;

[0030] FIG2 is a schematic structural diagram of a deep peak regulation system for a boiler unit provided in an embodiment of the present application.

[0031] Figure: 10. Molten salt heat storage and energy release unit; 11. High-temperature molten salt storage tank; 12. Low-temperature molten salt storage tank; 13. Flue gas heat exchanger; 14. Steam heat exchanger; 141. Primary steam heat exchanger; 142. Secondary steam heat exchanger; 15. Pulverized coal heating device; 16. Feed water heating device; 161. Molten salt feed water medium-temperature heat exchanger; 162. Molten salt feed water superheater; 163. Molten salt feed water evaporator; 164. Molten salt feed water low-temperature heat exchanger; 17. Electric heating device; 171. Bypass; 172. Switch valve; 18. Low-temperature molten salt pump; 19. High-temperature molten salt pump; 20. Boiler circulation unit; 21. Boiler unit; 211. Steam release assembly; 212. Smoke exhaust assembly; 213. Coal inlet assembly; 22. Steam turbine; 221, high-pressure cylinder; 222, medium-pressure cylinder; 223, low-pressure cylinder; 23, condensate recovery assembly; 231, steam heater; 232, air-cooled condenser; 233, condensate pump; 234, deaerator; 235, drive pump; 236, pre-pump; 237, small steam turbine. DETAILED DESCRIPTION

[0032] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present application, but should not be understood as limiting the present application.

[0033] 1-2 , a molten salt thermal energy storage and release unit and a deep peak regulation system for a boiler unit according to an embodiment of the present application will be described below.

[0034] The embodiment of the present application provides a molten salt thermal energy storage and release unit 10, as shown in Figure 1. The molten salt thermal energy storage and release unit 10 mainly includes three parts: a molten salt storage component, a heat exchange energy storage component, and a heat exchange energy release component. The molten salt storage component includes a high-temperature molten salt storage tank 11 and a low-temperature molten salt storage tank 12. The heat exchange energy storage component and the heat exchange energy release component are respectively connected to the high-temperature molten salt storage tank 11 and the low-temperature molten salt storage tank 12 through corresponding pipelines.

[0035] Specifically, the heat exchange and energy storage component connecting the high-temperature molten salt storage tank 11 and the low-temperature molten salt storage tank 12 includes a flue gas heat exchange device 13 and a steam heat exchange device 14. The molten salt located in the low-temperature molten salt storage tank 12 is heated in turn by the flue gas heat exchange device 13 and the steam heat exchange device 14 and then flows into the high-temperature molten salt storage tank 11; the heat exchange and energy release component connecting the high-temperature molten salt storage tank 11 and the low-temperature molten salt storage tank 12 includes a pulverized coal heating device 15 and a feed water heating device 16. The molten salt located in the high-temperature molten salt storage tank 11 releases energy through the pulverized coal heating device 15 and / or the feed water heating device 16 and then flows into the low-temperature molten salt storage tank 12.

[0036] The molten salt thermal energy storage and release unit 10 can effectively utilize multiple energy sources through the flue gas heat exchanger 13 and the steam heat exchanger 14. It can absorb low-temperature heat sources at lower temperatures and high-temperature heat sources at higher temperatures. Furthermore, the molten salt thermal energy storage and release unit 10 can also achieve temperature-matched, multi-path release based on the required temperatures of different locations, effectively improving the absorption and utilization efficiency of energy or heat. Furthermore, the unit can heat pulverized coal through the pulverized coal heating device 15, effectively improving the combustion stability of the associated boiler during low-load combustion.

[0037] Specifically, the flue gas heat exchanger 13 includes a flue gas inlet, a flue gas outlet, a molten salt inlet, and a molten salt outlet. The flue gas inlet and the flue gas outlet are interconnected, and the molten salt inlet and the molten salt outlet are interconnected. When the high-temperature flue gas passes through the flue gas heat exchanger 13 via the flue gas inlet and the flue gas outlet, the molten salt flowing through the flue gas heat exchanger 13 can obtain some of the heat carried by the high-temperature flue gas, thereby effectively utilizing the residual heat in the high-temperature flue gas, reducing heat loss and waste, and improving heat utilization. Similarly, the steam heat exchanger 14 is also provided with a steam inlet, a steam outlet, a molten salt inlet, and a molten salt outlet in the corresponding area. Similar to the flue gas heat exchanger 13, the molten salt passes through the steam heat exchanger 14 via the molten salt inlet and the molten salt outlet, storing energy in the process.

[0038] Specifically, the above-mentioned pulverized coal heating device 15 includes a pulverized coal inlet, a pulverized coal outlet, a molten salt inlet and a molten salt outlet, wherein the pulverized coal inlet and the pulverized coal outlet are connected, and the molten salt inlet and the molten salt outlet are connected. When the molten salt carrying a certain amount of heat passes through the pulverized coal heating device 15 through the above-mentioned molten salt inlet and the molten salt outlet, the pulverized coal flowing through the pulverized coal heating device 15 can obtain part of the heat carried by the high-temperature molten salt, thereby heating the pulverized coal. Heating pulverized coal can not only increase the temperature of the pulverized coal, but also enable the pulverized coal to burn more fully (the stability of the boiler during low-load operation can be improved by preheating the pulverized coal, reducing the generation of harmful substances in the flue gas, and improving the variable load response rate of the unit). Since the heat released by the molten salt is obtained from the corresponding boiler unit 21, the above-mentioned device can also achieve effective utilization of energy without affecting the normal operation of the boiler, thereby reducing energy waste. The structure and working principle of the above-mentioned feed water heating device 16 are basically the same as those of the pulverized coal heating device 15, and will not be repeated here. The water in the feed water heating device 16 can be provided by the outside of the system.

[0039] It should be noted that, for safety reasons, a switch bypass is provided outside the pulverized coal heating device 15. Valves for controlling the on / off status of the pipelines are also provided upstream and downstream of the pulverized coal heating device 15, as shown in Figure 1. When the pulverized coal does not need to be heated, the high-temperature molten salt flows directly through the switch bypass to the feedwater heating device 16.

[0040] In some embodiments, the heat exchange and energy storage assembly further includes an electric heating device 17 located between the steam heat exchange device 14 and the high-temperature molten salt storage tank 11 .

[0041] In order to further improve the energy storage effect of molten salt, ensure that the obtained high-temperature molten salt can release enough heat to heat the relevant water and steam when the grid load is large, and realize the rapid response function of the molten salt heat storage and energy release unit 10 during system peak load regulation, it is necessary to install the above-mentioned electric heating device 17 thereon.

[0042] In some embodiments, a bypass 171 for the circulation of molten salt working medium is further provided outside the electric heating device 17 , and a switch valve 172 is installed on the bypass 171 .

[0043] When the low-temperature molten salt reaches the set temperature after heat exchange and energy storage in the flue gas heat exchange device 13 and the steam heat exchange device 14, it is no longer necessary to use an electric heater to heat it. At this time, it is necessary to open the switch valve 172 on the bypass 171, and the high-temperature molten salt can flow through the bypass 171 into the high-temperature molten salt storage tank 11.

[0044] It should be noted that a valve with an opening and closing function is also provided outside the electric heating device 17, as shown in Figure 1. When the molten salt temperature is high enough or the electric heating device 17 fails, the valve needs to be closed and the switch valve 172 on the bypass 171 needs to be opened.

[0045] In some embodiments, the steam heat exchange device 14 includes a primary steam heat exchanger 141 and a secondary steam heat exchanger 142 arranged in sequence along the flow direction.

[0046] The sequential arrangement of the above-mentioned two-stage heat exchange structures can effectively utilize the heat carried by the steam. As shown in Figure 2, high-temperature steam flows sequentially through the first-stage steam heat exchanger 141 and the second-stage steam heat exchanger 142. During this process, the molten salt flows sequentially through the second-stage steam heat exchanger 142 and the first-stage steam heat exchanger 141, thereby achieving secondary heating of the molten salt. The lower-temperature molten salt is heated by the lower-temperature steam when flowing through the second-stage steam heat exchanger 142, and then flows into the first-stage steam heat exchanger 141 for secondary heating by the higher-temperature steam. This secondary heating process can effectively improve the utilization rate of the molten salt of the heat carried by the steam.

[0047] Of course, it should be noted that a bypass 171 having a similar structure to that of the electric heating device 17 is also provided outside the steam heat exchange device 14 .

[0048] In order to provide power for the low-temperature molten salt to flow from the low-temperature molten salt storage tank 12 to the high-temperature molten salt storage tank 11, in some embodiments, the heat exchange and energy storage assembly further includes a low-temperature molten salt pump 18. The low-temperature molten salt pump 18 can provide power for the flow of the low-temperature molten salt.

[0049] When releasing the energy stored in the molten salt thermal energy storage and release unit 10 , it can be selected according to actual needs.

[0050] In order to increase the diversity of uses of the released energy, in some embodiments, the heat exchange energy release component includes a first energy release branch and a second energy release branch, the coal powder heating device 15 is located on the first energy release branch, and the number of the water heating devices 16 is at least two and they are respectively distributed on the first energy release branch and the second energy release branch, as shown in Figure 1; the molten salt located in the high-temperature molten salt storage tank 11 flows into the first energy release branch and / or the second energy release branch, and then merges and flows into the low-temperature molten salt storage tank 12.

[0051] Specifically, when only the above-mentioned first energy release branch is set in a connected state, the energy stored in the molten salt thermal storage and energy release unit 10 can be released through the coal powder heating device 15 and the partial water heating device 16, and the released energy is used to heat the coal powder and part of the water; when only the above-mentioned second energy release branch is set in a connected state, the energy stored in the molten salt thermal storage and energy release unit 10 can be released through the partial water heating device 16.

[0052] The specific purpose and distribution position of the above-mentioned water heating device 16 are described below:

[0053] In some embodiments, as shown in Figure 1, the feed water heating device 16 includes a molten salt feed water medium heat exchanger 161 located on the first energy release branch and a molten salt feed water superheater 162 and a molten salt feed water evaporator 163 located on the second energy release branch. The molten salt located in the high-temperature molten salt storage tank 11 flows through the pulverized coal heating device 15 and the molten salt feed water medium heat exchanger 161 in sequence through the first energy release branch, and / or flows through the molten salt feed water superheater 162 and the molten salt feed water evaporator 163 in sequence through the second energy release branch, and then flows into the low-temperature molten salt storage tank 12.

[0054] In some embodiments, a molten salt feed water low temperature heat exchanger 164 is further provided on the second energy release branch, the molten salt feed water low temperature heat exchanger 164 is connected to the boiler unit 21, and the condensed water is connected to the boiler unit 21 through the molten salt feed water low temperature heat exchanger 164.

[0055] The different feedwater heating devices 16 described above can generate different amounts of heat due to their different locations and connection relationships. In this embodiment, by selecting different energy release branches, it is possible to achieve multi-path release of energy at different temperatures, thereby realizing the cascade utilization of molten salt energy.

[0056] Whether the two different energy release branches are connected can be adjusted according to the actual needs of the system. It should be noted that both energy release branches are equipped with valves, and the opening and closing of the relevant valves can be controlled to control whether the molten salt is driven to flow to release heat, as well as the flow path and distribution ratio of the molten salt.

[0057] In order to drive the high-temperature molten salt to flow from the high-temperature molten salt storage tank 11 to the low-temperature molten salt storage tank 12, in some embodiments, the heat exchange and energy release component also includes a high-temperature molten salt pump 19. The molten salt in the high-temperature molten salt storage tank 11 flows into the low-temperature molten salt storage tank 12 through the coal powder heating device 15 and the water supply heating device 16 under the drive of the high-temperature molten salt pump 19.

[0058] It is understood that the molten salt thermal energy storage and release unit 10 provided in this embodiment has a variety of different energy storage and release structures, which can effectively utilize multiple heat sources. In addition, the device can heat the pulverized coal through the pulverized coal heating device 15, thereby effectively improving the combustion stability of the relevant boiler during low-load combustion.

[0059] The embodiment of the present application also provides a deep peak-shaving system for a boiler unit, as shown in Figure 2. The deep peak-shaving system for a boiler unit includes a molten salt thermal energy storage and release unit 10 and a boiler circulation unit 20. The molten salt thermal energy storage and release unit 10 is any of the molten salt thermal energy storage and release units 10 described above; the boiler circulation unit 20 includes a boiler unit 21, a steam turbine 22, and a condensed water recovery component 23 that are interconnected. The boiler unit 21 cooperates with the heat exchange energy storage component and the heat exchange energy release component in the molten salt thermal energy storage and release unit 10, the steam turbine 22 cooperates with the heat exchange energy release component, and the condensed water recovery component 23 cooperates with the steam turbine 22 and the heat exchange energy storage component.

[0060] Under the action of the molten salt heat storage and energy release unit 10, the energy released by the boiler circulation unit 20 in some stages can be effectively stored and transported to the boiler unit 21, the steam turbine 22 and the condensate recovery component 23, so as to realize the reuse of the released energy. The deep peak-shaving system of the boiler unit can enable the boiler unit 21 to operate flexibly under variable load conditions by applying the above-mentioned molten salt heat storage and energy release unit 10. At the same time, it also improves the load response efficiency of the power grid when switching from normal periods to peak periods and low load periods, increases the peak-shaving depth of the unit, and is of great significance to improving the service level of the power system. In addition, the deep peak-shaving system of the boiler unit also uses the molten salt heat storage and energy release unit 10 to effectively improve the combustion stability of the boiler unit 21 at low loads. At the same time, it can also improve the heat utilization rate by heat exchange when the power grid is in a high-load period, realize the cascade utilization of molten salt energy during energy release, and has better heat exchange efficiency than the existing energy storage system, which can help increase the power generation of the steam turbine 22.

[0061] It should be noted that the condensate recovery assembly 23 not only recovers condensate but also performs heat exchange during this recovery process, raising the temperature of the water returning to the boiler unit 21 and even converting it into steam carrying a certain amount of heat. This device can help reduce the amount of air drawn by the steam turbine 22 during operation, allowing more steam to be used for power generation and improving power generation efficiency.

[0062] In some embodiments, the boiler unit 21 includes a steam release component 211, a smoke exhaust component 212 and a coal inlet component 213. The steam release component 211 cooperates with the steam heat exchange device 14 in the heat exchange and energy storage component, the smoke exhaust component 212 cooperates with the flue gas heat exchange device 13, and the coal inlet component 213 cooperates with the coal powder heating device 15; the steam turbine 22 includes a high-pressure cylinder 221, an intermediate-pressure cylinder 222 and a low-pressure cylinder 223 arranged coaxially in sequence, and the steam generated by the boiler unit 21 flows into the steam release component 211 and the high-pressure cylinder 221 respectively; at least part of the feedwater heating device 16 is connected to the intermediate-pressure cylinder 222 through a pipeline, and part of the steam in the high-pressure cylinder 221 and at least part of the steam and / or liquid generated at the feedwater heating device 16 flow into the intermediate-pressure cylinder 2 22, the low-pressure cylinder 223 is connected to the generator for driving the generator to generate electricity; the condensate recovery component 23 includes a steam heater 231, an air-cooled condenser 232, a condensate pump 233, a deaerator 234 and a drive pump 235 group. The number of steam heaters 231 is at least three. The high-pressure cylinder 221, the medium-pressure cylinder 222 and the low-pressure cylinder 223 are connected to at least one steam heater 231. The steam heat exchanger 14 is connected to the deaerator 234 through a pipeline, and the steam discharged from the steam heat exchanger 14 flows into the deaerator 234 through a pipeline; under the drive of the drive pump 235 group, the condensate generated at the air-cooled condenser 232 and the condensate pump 233 flows through the steam heater 231 and the deaerator 234 in sequence, and flows back to the boiler unit 21.

[0063] The boiler circulation unit 20 is used as follows:

[0064] Most of the steam generated by the boiler unit 21 during operation enters the high-pressure cylinder 221 of the steam turbine 22 to perform work. The high-pressure cylinder 221 comprises two stages: the first stage and the second stage. After entering the first stage, the steam is divided into two parts: one part enters the second stage of the high-pressure cylinder 221, and the other part is used as exhaust air to serve as the steam source for the steam heater 231 corresponding to the first stage. The steam entering the second stage of the high-pressure cylinder 221 is divided into two parts upon exiting the second stage. One part enters the superheater of the boiler unit 21 for heating, subsequently forming medium-pressure, high-temperature steam that enters the intermediate-pressure cylinder 222 to perform work, while the other part is used as exhaust air to serve as the steam source for the steam heater 231 corresponding to the second stage.

[0065] The superheater reheats the working medium (i.e., steam) that has already performed work and has reduced its temperature and pressure, returning it to high-temperature, intermediate-pressure steam. As shown in Figure 2, the steam at the outlet of the high-pressure cylinder 221 is fed into the boiler assembly for reheating, with the remainder used for extraction, before being discharged into the intermediate-pressure cylinder 222.

[0066] The superheater is an important component for improving the thermal efficiency of the boiler unit 21 and increasing the output.

[0067] The steam after the heat treatment can be divided into two streams, one of which enters the steam heat exchange device 14 of the molten salt thermal energy storage and release unit 10, and the other enters the intermediate pressure cylinder 222 of the steam turbine 22. The steam flowing into the intermediate pressure cylinder 222 is divided into two branches, one of which is the steam after the heat treatment, and the other is the steam discharged from the molten salt feed water superheater 162 of the molten salt thermal energy storage and release unit 10. The above two steam streams are mixed and enter the intermediate pressure cylinder 222. The intermediate pressure cylinder 222 includes three stage groups, namely the first stage group, the second stage group and the third stage group. After the steam entering the intermediate pressure cylinder 222 is processed in the first stage group, part of it enters the corresponding steam heater 231 through exhaust, and the other part enters the second stage group of the intermediate pressure cylinder 222. The steam in the second stage of the intermediate pressure cylinder 222 enters the deaerator 234 after being pumped out, and then enters the small steam turbine 237. The small steam turbine 237 can serve as a power source for driving the pre-pump 236 and the drive pump 235. The remaining steam enters the third stage of the intermediate pressure cylinder 222. At the outlet of the third stage, part of the steam is pumped out and enters the corresponding steam heater 231, and the remaining steam enters the low pressure cylinder 223. The low pressure cylinder 223 also includes three different stages. After undergoing two pumping processes consistent with the above process, the pumped air enters the steam heater 231 corresponding to the relevant stage, and the exhaust steam enters the air-cooled condenser 232. The exhaust steam entering the air-cooled condenser 232 is condensed and sent to the above-mentioned different steam heaters 231 and deaerator 234 in sequence through the condensate pump 233, and is driven by the pre-pump 236, the drive pump 235, etc. to flow through the remaining steam heaters 231 in sequence, and forms steam after heat absorption treatment at various levels, and finally flows into the boiler unit 21, repeating the above-mentioned work process.

[0068] By controlling the opening and closing of relevant valves and the degree of opening, the amount of steam entering different pipes and components can be changed.

[0069] In some embodiments, at least one drain outlet is provided at the driving pump 235 group, and the drain outlet is connected to the water inlet of the water heating device 16.

[0070] Specifically, the outlet of the pre-pump 236 has two pipelines, one of which is connected to the drive pump 235, and the other forms a drain C after passing through a valve. Drain C is divided into two branches and is respectively connected to the water-side inlet of the molten salt feed water medium-temperature heat exchanger 161 and the molten salt feed water evaporator 163. Similarly, the outlet of the drive pump 235 is also provided with two pipelines, one of which is connected to the steam heater 231 corresponding to the first-stage group of the intermediate-pressure cylinder 222, and the other forms drain B, which is connected to the water-side inlet of the molten salt feed water low-temperature heat exchanger 164. The pipeline on the water side outlet of the molten salt feed water low-temperature heat exchanger 164 forms outlet A. The outlet of the steam heater 231 corresponding to the first-stage group of the high-pressure cylinder 221 can merge with outlet A and feed water into the boiler unit 21.

[0071] Specifically, the pipe at the water side outlet of the above-mentioned molten salt feed water neutral heat exchanger 161 forms an outlet D. The steam generated at the above-mentioned molten salt feed water neutral heat exchanger 161 can be discharged through the outlet D to the third stage group of the intermediate pressure cylinder 222 of the turbine 22 and perform work.

[0072] The following describes the working process of the deep peak regulation system of the boiler unit when the molten salt thermal energy storage unit 10 is in the heat storage state:

[0073] When the grid load is at a low point at night, the boiler circulation unit 20 is in a low-load operation state. Part of the reheated steam in the boiler unit 21 flows into the steam heat exchange device 14 through the valve by means of extraction, thereby heating the molten salt. The steam that releases part of the heat is then transported to the deaerator 234 through the valve and pipeline. The molten salt flowing out of the lower end outlet of the low-temperature molten salt storage tank 12 is driven by the low-temperature Rongyan pump, passes through the valve and the corresponding pipeline into the flue gas heat exchange device 13 for preheating, and then flows through the corresponding valve and is processed in sequence by the above-mentioned secondary steam heat exchanger 142 and the primary steam heat exchanger 141 before flowing into the electric heating device 17 (i.e., the electric heater) for further heating, and then flows into the high-temperature molten salt storage tank 11 through the valve and pipeline through the inlet located at the top, completing the heat storage of the low-temperature molten salt.

[0074] Under the lowest operating condition of the boiler circulation unit 20, the device can store heat of low-temperature molten salt while ensuring the highest efficiency, and achieve deep peak regulation of the stage group by extracting steam and storing heat, thereby expanding the operating range of the unit. At the same time, it improves the stability of the boiler during low-load operation by preheating pulverized coal, reduces the generation of harmful substances in the flue gas, and improves the variable load response rate of the unit.

[0075] When the power grid is in a normal period, the boiler circulation unit 20 operates at normal load and does not need to be peak-shaving. At this time, there is no need to extract the steam generated in the boiler unit 21 and heat the molten salt heat storage and energy release unit 10. Correspondingly, outlet B and outlet C are also in a closed state. At this time, it can be determined whether to perform molten salt heat storage operations based on the molten salt storage in the high-temperature molten salt storage tank 11 to ensure that there is enough high-temperature molten salt to heat steam and water when the power grid load is high during peak hours, so as to achieve rapid response of the molten salt heat storage system to the peak load of the unit. If there is a demand for heat storage, the low-temperature molten salt in the low-temperature molten salt storage tank 12 is directly heated through the flue gas heat exchange device 13 and the electric heating device 17 through the valve control, without the participation of the steam heat exchange device 14.

[0076] The following describes the working process of the deep peak regulation system of the boiler unit when the molten salt thermal energy storage unit 10 is in the heat release state:

[0077] When the grid load is at its peak, the boiler unit 21 in the boiler circulation unit 20 is in a high-load operation state. At this time, the steam can be prevented from entering the molten salt heat storage and energy release unit 10 by closing the valve. At the same time, the high-temperature molten salt pump 19 is turned on, the pulverized coal heating device 15 and the related valves and switch bypasses on its periphery are closed (i.e., the first energy release branch is closed and the second energy release branch is opened), so that the high-temperature molten salt flows through the molten salt feed water superheater 162, the molten salt feed water evaporator 163 and the molten salt feed water low-temperature heat exchanger 164 in sequence and releases heat, and finally flows into the low-temperature molten salt storage tank 12 through the upper inlet.

[0078] Part of the feed water from the drive pump 235 and the pre-pump 236 forms steam and enters the steam turbine 22 to perform work to increase the power of the generator. The remaining feed water is mixed with the feed water heated by the steam heater 231 and enters the boiler unit 21 to reduce the steam superheater extraction and make more steam available for the steam turbine 22 to perform work.

[0079] When the grid load is at its lowest point at night, the boiler circulation unit 20 is in a low-load operating state. At this time, the high-temperature molten salt in the high-temperature molten salt storage tank 11 flows through the valve into the first energy release branch under the drive of the high-temperature molten salt pump 19, and preheats the pulverized coal through the pulverized coal heating device 15 to improve the stability of the furnace combustion. At this time, the valve on the bypass outside the pulverized coal heating device 15 is in a closed state. The molten salt after the above-mentioned preliminary heat exchange treatment then flows through the valve into the molten salt feed water medium heat exchanger 161 for further heat exchange, and finally enters the low-temperature molten salt storage tank 12 through the valve. The steam generated at the molten salt-feed water medium heat exchanger enters the medium-pressure cylinder 222 to perform work.

[0080] The amount of heat absorbed and released by the molten salt energy storage system is determined by the demand of the boiler unit 21 at different periods of grid load, and is adjusted by switching between pipeline valves and the electric auxiliary heating system.

[0081] It is understood that the present application forms a molten salt thermal energy storage and release unit 10 by providing multiple heat storage and release structures with different temperature ranges. The deep peak-shaving system of the boiler unit coupled with the above-mentioned molten salt thermal energy storage and release unit 10 enables the boiler circulation unit 20 to respond quickly when switching loads, improves its load response rate, increases the peak-shaving depth of the unit, and enhances the flexible operation capability of the unit. During the off-peak period of the power grid, the molten salt thermal energy storage and release unit 10 can be adjusted according to the power generation required by the power grid and the operating characteristics of the boiler circulation unit 20, helping to reduce the power generation load of the boiler circulation unit 20, while improving its combustion stability by preheating the pulverized coal. During normal periods, low-temperature molten salt heating can be performed as needed through flue gas heat exchange and electric heating to improve energy utilization. Under high-load conditions, superheated steam can be generated for use by the steam turbine 22 through heat exchange to increase the power generation of the unit. At the same time, the generated condensate is heated and supplied to the boiler unit 21, reducing the exhaust from the high-pressure cylinder 221 of the steam turbine 22, allowing more steam to be used for work. The deep peak regulation system for boiler units provided in this embodiment is of great significance to improving the service level of the power system.

[0082] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0083] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0084] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0085] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0086] In this application, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0087] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A molten salt thermal energy storage unit, characterized in that: include: A molten salt storage assembly, the molten salt storage assembly comprising a high-temperature molten salt storage tank (11) and a low-temperature molten salt storage tank (12); A heat exchange and energy storage component, wherein the heat exchange and energy storage component is connected to the high-temperature molten salt storage tank (11) and the low-temperature molten salt storage tank (12), and the heat exchange and energy storage component includes a flue gas heat exchange device (13) and a steam heat exchange device (14); the molten salt in the low-temperature molten salt storage tank (12) is heated in sequence by the flue gas heat exchange device (13) and the steam heat exchange device (14) and then flows into the high-temperature molten salt storage tank (11); A heat exchange energy release component is provided, wherein the heat exchange energy release component is connected to the high-temperature molten salt storage tank (11) and the low-temperature molten salt storage tank (12), and the heat exchange energy release component includes a coal powder heating device (15) and a water supply heating device (16). The molten salt in the high-temperature molten salt storage tank (11) releases energy through the coal powder heating device (15) and / or the water supply heating device (16) and then flows into the low-temperature molten salt storage tank (12).

2. The molten salt thermal energy storage unit according to claim 1, characterized in that: The heat exchange and energy storage assembly further includes an electric heating device (17) located between the steam heat exchange device (14) and the high-temperature molten salt storage tank (11); and / or the steam heat exchange device (14) includes a primary steam heat exchanger (141) and a secondary steam heat exchanger (142) arranged in sequence along the flow direction.

3. The molten salt thermal energy storage unit according to claim 2, characterized in that: A bypass (171) for the molten salt working medium to flow is also provided outside the electric heating device (17), and a switch valve (172) is installed on the bypass (171).

4. The molten salt thermal energy storage unit according to claim 1, characterized in that: The heat exchange energy release component comprises a first energy release branch and a second energy release branch, and the molten salt in the high-temperature molten salt storage tank (11) flows into the first energy release branch and / or the second energy release branch, and then merges and flows into the low-temperature molten salt storage tank (12); The pulverized coal heating device (15) is located on the first energy release branch, and the number of the feed water heating devices (16) is at least two and they are respectively distributed on the first energy release branch and the second energy release branch.

5. The molten salt thermal energy storage unit according to claim 4, characterized in that: The feed water heating device (16) includes a molten salt feed water medium heat exchanger (161) located on the first energy release branch and a molten salt feed water superheater (162) and a molten salt feed water evaporator (163) located on the second energy release branch. The molten salt in the high-temperature molten salt storage tank (11) flows through the pulverized coal heating device (15) and the molten salt feed water medium heat exchanger (161) in sequence through the first energy release branch, and / or flows through the molten salt feed water superheater (162) and the molten salt feed water evaporator (163) in sequence through the second energy release branch, and then flows into the low-temperature molten salt storage tank (12).

6. The molten salt thermal energy storage unit according to claim 4 or 5, characterized in that: A molten salt feed water low-temperature heat exchanger (164) is also provided on the second energy release branch. The molten salt feed water low-temperature heat exchanger (164) is connected to the boiler unit (21), and the condensed water is connected to the boiler unit (21) via the molten salt feed water low-temperature heat exchanger (164).

7. The molten salt thermal energy storage unit according to claim 1, characterized in that: The heat exchange energy storage component further comprises a low-temperature molten salt pump (18), and the molten salt in the low-temperature molten salt storage tank (12) is driven by the low-temperature molten salt pump (18) to flow into the high-temperature molten salt storage tank (11) through the flue gas heat exchange device (13) and the steam heat exchange device (14); And / or, the heat exchange energy release component also includes a high-temperature molten salt pump (19), and the molten salt located in the high-temperature molten salt storage tank (11) flows into the low-temperature molten salt storage tank (12) through the coal powder heating device (15) and the water supply heating device (16) under the drive of the high-temperature molten salt pump (19).

8. A deep peak regulation system for a boiler unit, characterized in that: include: A molten salt thermal energy storage and release unit (10), wherein the molten salt thermal energy storage and release unit (10) is the molten salt thermal energy storage and release unit according to any one of claims 1 to 7; A boiler circulation unit (20), the boiler circulation unit (20) comprising a boiler unit (21), a steam turbine (22) and a condensate recovery assembly (23) which are interconnected, the boiler unit (21) cooperating with the heat exchange energy storage assembly and the heat exchange energy release assembly, the steam turbine (22) cooperating with the heat exchange energy release assembly, and the condensate recovery assembly (23) cooperating with the steam turbine (22) and the heat exchange energy storage assembly.

9. The deep peak regulation system of the boiler unit according to claim 8, characterized in that: The boiler unit (21) comprises a steam release component (211), a smoke exhaust component (212) and a coal feed component (213); the steam release component (211) cooperates with the steam heat exchange device (14) in the heat exchange and energy storage component; the smoke exhaust component (212) cooperates with the flue gas heat exchange device (13); and the coal feed component (213) cooperates with the pulverized coal heating device (15); The steam turbine (22) comprises a high-pressure cylinder (221), an intermediate-pressure cylinder (222) and a low-pressure cylinder (223) coaxially arranged in sequence, the steam generated by the boiler unit (21) flows into the steam release component (211) and the high-pressure cylinder (221) respectively; at least part of the feedwater heating device (16) is connected to the intermediate-pressure cylinder (222) through a pipeline, and part of the steam in the high-pressure cylinder (221) and at least part of the steam and / or liquid generated at the feedwater heating device (16) flow into the intermediate-pressure cylinder (222); The condensate recovery assembly (23) includes a steam heater (231), an air-cooled condenser (232), a condensate pump (233), a deaerator (234) and a drive pump (235) group. The number of the steam heaters (231) is at least three. The high-pressure cylinder (221), the medium-pressure cylinder (222) and the low-pressure cylinder (223) are connected to at least one of the steam heaters (231). The steam heat exchange device (14) is connected to the deaerator (234) through a pipeline. The steam discharged from the steam heat exchange device (14) flows into the deaerator (234) through a pipeline. Under the drive of the drive pump (235) group, the condensate generated at the air-cooled condenser (232) and the condensate pump (233) flows through the steam heater (231) and the deaerator (234) in sequence and flows back into the boiler unit (21).

10. The deep peak regulation system of the boiler unit according to claim 9, characterized in that: The driving pump (235) group is provided with at least one drain port, and the drain port is connected to the water inlet of the water supply heating device (16).

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