CN118009779A - Fused salt heat-storage energy-release unit and boiler unit deep peak regulation system - Google Patents

Abstract

The invention provides a fused salt heat storage and energy release unit and a boiler unit deep peak regulation system, wherein the fused salt heat storage and energy release unit comprises a fused salt storage assembly, a heat exchange energy storage assembly and a heat exchange energy release assembly, and the fused salt storage assembly comprises a high-temperature fused salt storage tank and a low-temperature fused salt storage tank; the heat exchange energy storage component is connected with 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 flows into the high-temperature molten salt storage tank after being heated by the flue gas heat exchange device and the steam heat exchange device in sequence; the heat exchange energy release assembly is connected with the high-temperature molten salt storage tank and the low-temperature molten salt storage tank, and comprises a coal dust heating device and a water supply heating device, and molten salt in the high-temperature molten salt storage tank flows into the low-temperature molten salt storage tank after being released by the coal dust heating device and/or the water supply heating device. The invention provides a fused salt heat storage and energy release unit and a boiler unit deep peak regulation system which are flexible in peak regulation and high in energy utilization rate.

Description

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

Technical Field

The present invention relates to the technical field of boiler peak regulation, and in particular to a molten salt thermal energy storage and release unit and a deep peak regulation system for a boiler unit.

Background technique

Due to the unpredictability and discontinuity of renewable energy generation, unstable electricity is generated, which affects the quality of power grid electricity and prevents some renewable energy generation from entering the grid, resulting in the phenomenon of "wind and solar abandonment". In order to solve the problem of low proportion of renewable energy generation entering the grid, the current consumption of renewable energy electricity is mainly achieved through peak load regulation of thermal power units with a large proportion of power generation. In order to overcome the problems of slow peak load response and large hysteresis in traditional thermal power generation, many thermal power generation companies are currently improving energy storage technology to overcome the problem of poor peak load regulation performance.

As a technical means to change the spatial and temporal distribution of energy, energy storage technology can greatly improve the peak-shaving flexibility of power stations and alleviate the problem of power grid supply and demand balance. 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 promising peak-shaving methods for thermal power units. By coupling molten salt energy storage, the boiler can be kept running at medium and high loads while reducing the output of electrical load, thereby achieving flexible and rapid peak-shaving of power plants. However, conventional molten salt energy storage technology can only store and release high single-grade energy, with low energy utilization and easy to cause huge waste of energy.

Summary of the invention

The present invention is based on the inventor's discovery and understanding of the following facts and problems:

The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

To this end, an embodiment of the present invention proposes 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.

The molten salt heat storage and energy release unit provided in an embodiment of the present invention 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 connects 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 turn and then flows into the high-temperature molten salt storage tank; the heat exchange energy release component connects 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.

According to the molten salt thermal energy storage unit of the embodiment of the present invention, the molten salt thermal energy storage unit can realize the effective utilization of multi-grade energy through the flue gas heat exchange device and the steam heat exchange device, and can absorb low-temperature heat sources when the temperature is low, and can absorb high-temperature heat sources when the temperature is high; at the same time, the molten salt thermal energy storage unit can also realize the temperature matching multi-path release according to the different temperatures required by different parts, thereby effectively improving the absorption and utilization efficiency of energy or heat. In addition, the device can heat the pulverized coal through the pulverized coal heating device, thereby effectively improving the combustion stability of the relevant boiler during low-load combustion.

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

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.

In some embodiments, a bypass for the molten salt working medium to flow is further provided outside the electric heating device, and a switch valve is installed on the bypass.

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;

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.

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.

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.

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 via the molten salt feed water low-temperature heat exchanger.

In some embodiments, the heat exchange energy storage component further includes a low-temperature molten salt pump, and the molten salt in the low-temperature molten salt storage tank flows into the high-temperature molten salt storage tank through the flue gas heat exchange device and the steam heat exchange device under the drive of the low-temperature molten salt pump;

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.

The deep peak-shaving system of a boiler unit provided in an embodiment of the present invention comprises 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 comprises a boiler unit, a steam turbine and a condensate recovery component which 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.

According to the deep peak-shaving system of the boiler unit according to the embodiment of the present invention, 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 thermal storage and energy release unit, and at the same time, it also improves the load response efficiency when the power grid switches from normal periods to peak periods and low load periods, and increases the peak-shaving depth of the unit, which is of great significance to improving the service level of the power system. In addition, the above-mentioned deep peak-shaving system of the boiler unit also uses the molten salt thermal storage and energy release unit to effectively improve the combustion stability of the boiler unit at low loads, and 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, and realize the cascade utilization of molten salt energy during energy release. Compared with the existing energy storage system, it has better heat exchange efficiency and can help increase the power generation of the steam turbine.

In some embodiments, the boiler unit includes a steam release component, a smoke exhaust component and a coal inlet 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 inlet component cooperates with the pulverized coal heating device;

The steam turbine comprises a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder which are coaxially arranged in sequence, and 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 through 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;

The condensate recovery component includes a steam heater, an air-to-air condenser, a condensate pump, a deaerator and a driving 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 exchanger is connected to the deaerator through a pipeline. The steam discharged from the steam heat exchanger flows into the deaerator through a pipeline. Driven by the driving pump group, the condensate generated at the air-to-air condenser and the condensate pump flows through the steam heater and the deaerator in turn, and flows back to the boiler unit.

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

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

In the 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 exchange device; 14. Steam heat exchange device; 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-to-air condenser; 233. Condensate pump; 234. Deaerator; 235. Drive pump; 236. Pre-pump; 237. Small steam turbine.

Detailed ways

Embodiments of the present invention 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 invention, but should not be understood as limiting the present invention.

The following describes 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 invention in conjunction with Figures 1 and 2.

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

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 in the low-temperature molten salt storage tank 12 is heated by the flue gas heat exchange device 13 and the steam heat exchange device 14 in sequence 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 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.

The molten salt thermal storage and energy release unit 10 can realize the effective utilization of multi-grade energy through the flue gas heat exchange device 13 and the steam heat exchange device 14, and can absorb low-temperature heat sources when the temperature is low, and can absorb high-temperature heat sources when the temperature is high; at the same time, the molten salt thermal storage and energy release unit 10 can also realize the temperature matching and multi-path release according to the different temperatures required by different parts, thereby effectively improving the absorption and utilization efficiency of energy or heat. 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.

Specifically, the flue gas heat exchange device 13 includes a flue gas inlet, a flue gas outlet, a molten salt inlet and a molten salt outlet, wherein the flue gas inlet and the flue gas outlet are connected, and the molten salt inlet and the molten salt outlet are connected. When the high-temperature flue gas passes through the flue gas heat exchange device 13 through the flue gas inlet and the flue gas outlet, the molten salt flowing through the flue gas heat exchange device 13 can obtain part of the heat carried by the high-temperature flue gas, thereby realizing the effective utilization of the residual heat in the high-temperature flue gas, reducing heat loss and waste, and improving the utilization rate of heat. Similarly, the corresponding area of the steam heat exchange device 14 is also provided with a steam inlet, a steam outlet, a molten salt inlet and a molten salt outlet. Similar to the flue gas heat exchange device 13, the molten salt passes through the steam heat exchange device 14 through the molten salt inlet and the molten salt outlet and stores energy in the process.

Specifically, the 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 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 make the pulverized coal burn more fully (the stability of the boiler can be improved by preheating the pulverized coal when operating under low load conditions, reduce the generation of harmful substances in the flue gas, and increase 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 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 feedwater 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 feedwater heating device 16 can be provided by the outside of the system.

It should be noted that, for safety reasons, a switch bypass is provided outside the pulverized coal heating device 15, and valve structures for controlling the on-off of the pipeline 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 to the feedwater heating device 16 through the switch bypass.

In some embodiments, the heat exchange 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 .

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.

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

When the low-temperature molten salt reaches the set temperature after heat exchange and energy storage treatment by the flue gas heat exchange device 13 and the steam heat exchange device 14, it is not necessary to use an electric heater to heat it. At this time, it is necessary to open the switch valve 172 located on the bypass 171, and the high-temperature molten salt can flow into the high-temperature molten salt storage tank 11 through the bypass 171.

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.

In some embodiments, the steam heat exchange device 14 includes a primary steam heat exchanger 141 and a secondary steam heat exchanger 142 which are sequentially arranged along the flow direction.

The above-mentioned two-stage heat exchange structure is arranged in sequence to achieve effective utilization of the heat carried by steam. As shown in FIG2 , high-temperature steam flows through the first-stage steam heat exchanger 141 and the second-stage steam heat exchanger 142 in sequence. In this process, the molten salt flows through the second-stage steam heat exchanger 142 and the first-stage steam heat exchanger 141 in sequence, thereby achieving secondary heating of the molten salt, wherein the molten salt with a lower temperature is heated once by the steam with a lower temperature when flowing through the second-stage steam heat exchanger 142, and then flows into the first-stage steam heat exchanger 141 to be heated twice by the steam with a higher temperature. This secondary heating process can effectively improve the utilization rate of the heat carried by steam by the molten salt.

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 .

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 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.

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

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 supply 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; after 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, it merges and flows into the low-temperature molten salt storage tank 12.

Specifically, when only the above-mentioned first energy release branch is set in a connected state, the energy stored in the molten salt thermal energy storage unit 10 can be released through the coal powder heating device 15 and the partial water supply 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 energy storage unit 10 can be released through the partial water supply heating device 16.

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

In some embodiments, as shown in Figure 1, the feed water heating device 16 includes a molten salt feed water neutral 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 neutral 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.

In some embodiments, 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 through the molten salt feed water low temperature heat exchanger 164.

The above-mentioned different water heaters 16 can obtain different amounts of heat due to their different locations and connection relationships. In this embodiment, different temperatures can be released in multiple ways by selecting different energy release branches, thereby realizing the step-by-step utilization of molten salt energy.

Whether the above two different energy release branches are connected can be adjusted according to the actual needs of the system. It should be noted that valves are provided on both energy release branches, 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 molten salt flow path and distribution ratio.

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 driven by the high-temperature molten salt pump 19.

It is understandable that the molten salt thermal storage and energy release unit 10 provided in this embodiment has a variety of different energy storage structures and energy release structures, which can realize the effective utilization of multi-grade 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.

The embodiment of the present invention 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 unit 10 and a boiler circulation unit 20. The molten salt thermal energy storage unit 10 is any of the above-mentioned molten salt thermal energy storage unit 10; 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 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.

Under the action of the molten salt thermal energy storage 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 thermal energy storage unit 10, and at the same time improve the load response efficiency of the power grid when switching from normal periods to peak periods and low load periods, increase the peak-shaving depth of the unit, and have important significance for improving the service level of the power system. In addition, the deep peak-shaving system of the boiler unit also applies the molten salt thermal energy storage unit 10 to effectively improve the combustion stability of the boiler unit 21 at low loads, 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 22.

It should be noted that, in addition to being used to recover condensed water, the condensed water recovery component 23 also performs heat exchange through the recovery process to increase the temperature of the water returning to the boiler unit 21, and can even convert it into water vapor carrying a certain amount of heat. This device can help reduce the exhaust of the steam turbine 22 during operation, so that more steam can be used to do work, thereby improving power generation efficiency.

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 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, a medium-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 medium-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 medium-pressure cylinder 2 22, the low-pressure cylinder 223 is connected to the generator to drive the generator to generate electricity; the condensate recovery component 23 includes a steam heater 231, an air-to-air 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-to-air condenser 232 and the condensate pump 233 flows through the steam heater 231 and the deaerator 234 in turn, and flows back to the boiler unit 21.

The boiler circulation unit 20 is used as follows:

Most of the steam generated when the boiler unit 21 is working enters the high-pressure cylinder 221 of the steam turbine 22 to perform work. The high-pressure cylinder 221 includes two stages, namely the first stage and the second stage. After entering the first stage, the steam is divided into two parts, one part of which enters the second stage of the high-pressure cylinder 221, and the other part is used as exhaust gas as the steam source of 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 when it is discharged from the second stage, one part of which enters the superheater of the boiler unit 21 for heating, and then forms medium-pressure and high-temperature steam to enter the medium-pressure cylinder 222 to perform work, and the other part of the steam is used as exhaust gas as the steam source of the steam heater 231 corresponding to the second stage.

The superheater is a device that reheats the working medium (i.e., steam) that has done work and has a lower temperature and pressure into high-temperature medium-pressure steam. As shown in FIG2 , a small portion of the steam at the outlet of the high-pressure cylinder 221 is used for exhaust, and the rest is sent to the boiler assembly for reheating and then discharged into the medium-pressure cylinder 222.

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

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 unit 10, and the other enters the medium pressure cylinder 222 of the steam turbine 22. The steam flowing into the medium 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 unit 10. The above two steams are mixed and enter the medium pressure cylinder 222. The medium pressure cylinder 222 includes three stage groups, namely the first stage group, the second stage group and the third stage group. After being processed in the first stage group, part of the steam entering the medium pressure cylinder 222 enters the corresponding steam heater 231 through exhaust, and the other part enters the second stage group of the medium pressure cylinder 222. The steam in the second stage group of the medium pressure cylinder 222 enters the deaerator 234 after being evacuated, and then enters the small steam turbine 237 after being evacuated. The small steam turbine 237 can be used as a power source to drive the pre-pump 236 and the drive pump 235; the remaining steam enters the third stage group of the medium pressure cylinder 222. At the outlet of the third stage group, part of the steam enters the corresponding steam heater 231 after being evacuated, and the remaining steam enters the low pressure cylinder 223. The low pressure cylinder 223 also includes three different stages. After two evacuation treatments consistent with the above process, the evacuated air enters the steam heater 231 corresponding to the relevant stage group, 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 driving pump 235, etc. to flow through the remaining steam heaters 231 in sequence, and forms steam after various stages of heat absorption treatment, and finally flows into the boiler unit 21, and the above-mentioned work process is circulated.

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

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 .

Specifically, the outlet of the above-mentioned 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. The drain C is divided into two branches and is respectively connected to the water side inlet of the molten salt feed water medium heat exchanger 161 and the molten salt feed water evaporator 163. Similarly, the outlet of the above-mentioned drive pump 235 is also provided with two pipelines, one of which is always connected to the steam heater 231 corresponding to the first stage group of the medium pressure cylinder 222, and the other forms a drain B, and the drain B is connected to the water side inlet of the molten salt feed water low temperature heat exchanger 164. The pipeline of the water side outlet of the molten salt feed water low temperature heat exchanger 164 forms an outlet A. The outlet of the steam heater 231 corresponding to the first stage group of the above-mentioned high pressure cylinder 221 can be merged with the outlet A and the feed water enters the boiler unit 21.

Specifically, the pipeline at the water side outlet of the above-mentioned molten salt feed water neutral heat exchanger 161 forms an outlet D, and the steam energy generated at the above-mentioned molten salt feed water neutral heat exchanger 161 is discharged through the outlet D to the third stage group of the intermediate pressure cylinder 222 of the turbine 22 and performs work.

The working process of the above-mentioned boiler unit deep peak regulation system when the molten salt thermal energy storage unit 10 is in the heat storage state is described below:

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 exhaust, thereby heating the molten salt, and 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, and enters the flue gas heat exchange device 13 through the valve and the corresponding pipeline for preheating, and then flows through the corresponding valve and is processed in turn by the above-mentioned secondary steam heat exchanger 142 and the primary steam heat exchanger 141, and then flows into the electric heating device 17 (i.e., 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.

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, realize deep peak regulation of the stage group by extracting steam and storing heat, expand the operating range of the unit, and at the same time improve the stability of the boiler when operating under low-load conditions by preheating coal powder, reduce the generation of harmful substances in the flue gas, and improve the variable load response rate of the unit.

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-shifted. 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 large 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.

The working process of the above-mentioned boiler unit deep peak regulation system when the molten salt thermal energy storage unit 10 is in the heat release state is described below:

When the grid load is at a 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.

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.

When the grid load is at a low point at night, the boiler circulation unit 20 is in a low-load operation state. At this time, the high-temperature molten salt in the high-temperature molten salt storage tank 11 flows into the first energy release branch through the valve driven by the high-temperature molten salt pump 19, and preheats the pulverized coal through the pulverized coal heating device 15 to improve the stability of 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 neutral heat exchanger 161 for further heat exchange, and finally enters the low-temperature molten salt storage tank 12 through the valve, and the steam generated at the molten salt-feed water neutral heat exchanger enters the medium-pressure cylinder 222 to perform work.

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 the grid load, and is adjusted by switching between the pipeline valve and the electric auxiliary heating system.

It can be understood that the present invention forms a molten salt heat storage and energy release unit 10 by setting a plurality of heat storage and heat release structures with different temperature ranges. The deep peak-shaving system of the boiler unit coupled with the above-mentioned molten salt heat storage and energy release unit 10 can enable the boiler circulation unit 20 to respond quickly when switching loads, improve its load response rate, increase the peak-shaving depth of the unit, and enhance the flexible operation capability of the unit. During the off-peak period of the power grid, the molten salt heat storage and energy 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, to help reduce the power generation load of the boiler circulation unit 20, and at the same time improve its combustion stability by preheating the pulverized coal; in normal periods, low-temperature molten salt heating can be performed by flue gas heat exchange and electric heating as needed to improve the utilization rate of energy; under high load conditions, superheated steam for use by the steam turbine 22 can be generated by heat exchange to increase the power generation of the unit, and the generated condensed water can be heated and supplied to the boiler unit 21, reducing the exhaust at the high-pressure cylinder 221 of the steam turbine 22, so that more steam can be used for work. The deep peak regulation system of the boiler unit provided in this embodiment is of great significance to improving the service level of the power system.

In the description of the present invention, 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 invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature 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. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. 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 invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims (10)

1. A molten salt heat storage and release unit, comprising:

The molten salt storage assembly comprises a high-temperature molten salt storage tank (11) and a low-temperature molten salt storage tank (12);

The heat exchange energy storage assembly is connected with the high-temperature molten salt storage tank (11) and the low-temperature molten salt storage tank (12), and comprises a flue gas heat exchange device (13) and a steam heat exchange device (14), and molten salt in the low-temperature molten salt storage tank (12) flows into the high-temperature molten salt storage tank (11) after being heated by the flue gas heat exchange device (13) and the steam heat exchange device (14) in sequence;

The heat exchange energy release assembly is connected with the high-temperature molten salt storage tank (11) and the low-temperature molten salt storage tank (12), and comprises a coal dust heating device (15) and a water supply heating device (16), wherein molten salt in the high-temperature molten salt storage tank (11) flows into the low-temperature molten salt storage tank (12) after being released by the coal dust heating device (15) and/or the water supply heating device (16).

2. Molten salt heat and energy storage and release unit according to claim 1, characterized in that the heat exchange and energy storage assembly further comprises an electrical heating device (17) between the steam heat exchange device (14) and the high temperature molten salt storage tank (11);

And/or the steam heat exchange device (14) comprises a primary steam heat exchanger (141) and a secondary steam heat exchanger (142) which are sequentially arranged along the flow direction.

3. The molten salt heat storage and release unit according to claim 2, wherein a bypass (171) for circulating molten salt working medium is further arranged outside the electric heating device (17), and a switch valve (172) is arranged on the bypass (171).

4. The molten salt heat and energy storage and release unit according to claim 1, wherein the heat and energy exchange assembly comprises a first energy release branch and a second energy release branch, and molten salt in the high-temperature molten salt storage tank (11) is converged and flows into the low-temperature molten salt storage tank (12) after flowing into the first energy release branch and/or the second energy release branch;

The pulverized coal heating device (15) is located on the first energy release branch, and the number of the water supply heating devices (16) is at least two and is respectively distributed on the first energy release branch and the second energy release branch.

5. The molten salt heat and energy storage and release unit according to claim 4, wherein the feed water heating device (16) comprises a molten salt feed water intermediate temperature heat exchanger (161) positioned on the first energy release branch and a molten salt feed water superheater (162) and a molten salt feed water evaporator (163) positioned on the second energy release branch,

The molten salt in the high-temperature molten salt storage tank (11) sequentially flows through the pulverized coal heating device (15) and the molten salt water supply medium-temperature heat exchanger (161) through the first energy release branch, and/or sequentially flows through the molten salt water supply superheater (162) and the molten salt water supply evaporator (163) through the second energy release branch, and then flows into the low-temperature molten salt storage tank (12).

6. The molten salt heat and energy storage and release unit according to claim 4 or 5, wherein a molten salt water supply low-temperature heat exchanger (164) is further arranged on the second energy release branch, the molten salt water supply low-temperature heat exchanger (164) is connected with a boiler unit (21), and condensed water is connected with the boiler unit (21) through the molten salt water supply low-temperature heat exchanger (164).

7. The molten salt heat and energy storage and release unit according to claim 1, wherein the heat exchange and energy storage assembly further comprises a low-temperature molten salt pump (18), and molten salt in the low-temperature molten salt storage tank (12) flows into the high-temperature molten salt storage tank (11) through the flue gas heat exchange device (13) and the steam heat exchange device (14) under the driving of the low-temperature molten salt pump (18);

And/or the heat exchange energy release assembly further comprises a high-temperature molten salt pump (19), and molten salt in the high-temperature molten salt storage tank (11) flows into the low-temperature molten salt storage tank (12) through the coal dust heating device (15) and the water supply heating device (16) under the driving of the high-temperature molten salt pump (19).

8. A boiler unit depth peaking system, comprising:

A molten salt heat storage and release unit (10), wherein the molten salt heat storage and release unit (10) is a molten salt heat storage and release unit according to any one of claims 1 to 7;

The boiler circulation unit (20), boiler circulation unit (20) are including boiler unit (21), steam turbine (22) and the comdenstion water recovery subassembly (23) of intercommunication each other, boiler unit (21) with heat transfer energy storage subassembly with heat transfer energy release subassembly cooperatees, steam turbine (22) with heat transfer energy release subassembly cooperatees, comdenstion water recovery subassembly (23) with steam turbine (22) with heat transfer energy storage subassembly cooperatees.

9. The boiler unit depth peaking system according to claim 8, wherein the boiler unit (21) comprises a steam release assembly (211), a smoke exhaust assembly (212) and a coal inlet assembly (213), the steam release assembly (211) is matched with a steam heat exchange device (14) in the heat exchange and energy storage assembly, the smoke exhaust assembly (212) is matched with the flue gas heat exchange device (13), and the coal inlet assembly (213) is matched with the coal dust heating device (15);

The steam turbine (22) comprises a high-pressure cylinder (221), a middle-pressure cylinder (222) and a low-pressure cylinder (223) which are coaxially and sequentially arranged, and steam generated by the boiler unit (21) flows into the steam release assembly (211) and the high-pressure cylinder (221) respectively; at least part of the water supply heating device (16) is connected with the medium pressure cylinder (222) through a pipeline, and part of steam in the high pressure cylinder (221) and at least part of steam and/or liquid generated at the water supply heating device (16) flow into the medium pressure cylinder (222);

The condensate water recovery assembly (23) comprises a steam heater (231), an air-cooled condenser (232), a condensate water pump (233), a deaerator (234) and a driving pump (235), wherein 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 with at least one steam heater (231), the steam heat exchange device (14) is communicated with the deaerator (234) through a pipeline, and steam discharged by the steam heat exchange device (14) flows into the deaerator (234) through a pipeline; and under the drive of the drive pump (235), condensed water generated at the air-cooling condenser (232) and the condensed water pump (233) sequentially flows through the steam heater (231) and the deaerator (234) and flows back into the boiler unit (21).

10. The boiler unit depth peaking system of claim 9, wherein at least one drain is provided at the set of drive pumps (235), the drain being connected to the water inlet of the feedwater heating device (16).