A thermal power unit energy storage heat exchange device

Abstract

This invention discloses a thermal power unit energy storage heat exchange device, comprising an extraction steam reheat system, a molten salt heat storage system, and a high-temperature water heat storage system. The molten salt heat storage system includes a molten salt heat exchanger, and the high-temperature water heat storage system includes a high-temperature water heat exchanger. The inlet of the molten salt heat exchanger is connected to the outlet of the thermal power unit's reheater, the outlet of the molten salt heat exchanger is connected to the inlet of the high-temperature water heat exchanger, and the outlet of the high-temperature water heat exchanger is connected to the extraction steam reheat system. This device effectively avoids the direct entry of large amounts of high-temperature, high-pressure steam into the condenser after desuperheating and depressurization, thus preventing significant waste. It also avoids placing thermal load pressure on the condenser and circulating water system, achieving efficient energy utilization while effectively extending the system's service life.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat storage and heat exchange optimization of thermal power generating units, and relates to a heat storage and heat exchange device for a thermal power generating unit. BACKGROUND

[0002] The FCB (Fast Cut Back) function of a thermal power generating unit, namely, the "fast cut back" or "fast recovery" of the thermal power generating unit. The FCB function of the thermal power generating unit refers to that, when a running generating unit is decoupled from the power grid due to line faults or power grid faults and the like, all external power supply is removed instantaneously, and in the case that the boiler is not extinguished, the automatic control function of quickly shifting the external load to the self-use power operation or quickly reducing the load is realized. In the FCB process, the generator is decoupled from the system, the steam turbine generator unit and the boiler are normally operated, the bypass is quickly opened, the boiler quickly adjusts the load, and the state of quickly adjusting the unit output to maintain the real-time dynamic balance of the self-use power load and the unit output is realized. That is, the FCB function of the thermal power generating unit can maintain the boiler at the minimum load operation in the case that the unit is decoupled from the power grid, avoid the total loss of the unit self-use power, thereby shortening the recovery time of the unit and improving the operation economy of the unit. Secondly, the FCB function can also enable the unit to quickly recover the power supply when the power grid fails, which is of great significance to the stable operation of the power grid. In addition, the FCB function can also reduce the cost and life consumption of the boiler restart, and has a positive impact on the economic operation of the power plant.

[0003] At present, after the thermal power generating unit enters the FCB state, due to the fact that the steam turbine generator unit quickly sheds most of the external load and only runs with the self-use power, in response to the requirement of quickly reducing the unit load: the high-pressure regulating valve on the steam turbine side is quickly closed, and the high and low bypasses are quickly opened; due to the fact that the pressure of the boiler side is suddenly increased, the PCV valve or the safety door is actuated. In this process, a large amount of working medium of the boiler is discharged, and the heat of a large amount of low-pressure bypass steam received by the condenser is taken away by the circulating water. After the FCB is stably operated, in order to maintain the stability of the front pressure of the unit, the high and low pressure bypasses need to be opened for a long time, and a large amount of high-temperature and high-pressure steam is reduced in temperature and pressure and then enters the condenser through the high and low bypasses, which causes serious waste, and also causes certain thermal load pressure to the condenser and the circulating water system, thereby affecting the normal operation and service life thereof. SUMMARY

[0004] In view of the problems in the prior art, the application provides a heat storage and heat exchange device for a thermal power generating unit, thereby solving the problem that a large amount of high-temperature and high-pressure steam cannot be effectively utilized after the thermal power generating unit enters the FCB state, and simultaneously reducing the thermal load of the condenser and the circulating water system, thereby realizing the energy saving and consumption reduction of the unit.

[0005] The application is realized by the following technical scheme:

[0006] The application discloses a heat storage and heat exchange device for a thermal power generating unit.

[0007] The heat storage and heat exchange device comprises a steam extraction and heat recovery system, a molten salt heat storage and heat exchange system and a high-temperature water heat storage and heat exchange system.

[0008] The inlet of the molten salt heat storage and heat exchange device is connected with the outlet of a reheater of the thermal power generating unit, the outlet of the molten salt heat storage and heat exchange device is connected with the inlet of the high-temperature water heat storage and heat exchange device, and the outlet of the high-temperature water heat storage and heat exchange device is connected with the steam extraction and heat recovery system.

[0009] Preferably, the steam extraction and heat recovery system comprises a condenser, and the outlet of the reheater of the thermal power generating unit is connected with the condenser in an on-off mode.

[0010] Preferably, the molten salt heat storage and heat exchange system further comprises a molten salt heat release heat exchanger, and the inlet and the outlet of the molten salt heat release heat exchanger are connected with the steam extraction and heat recovery system.

[0011] Preferably, the high-temperature water heat storage and heat exchange system further comprises a high-temperature water heat release heat exchanger, and the inlet and the outlet of the high-temperature water heat release heat exchanger are connected with the steam extraction and heat recovery system.

[0012] Preferably, the high-temperature water heat storage and heat exchange system further comprises a pressure-bearing hot water tank, and the high-temperature water heat storage and heat exchange device and the high-temperature water heat release heat exchanger are connected with the hot water end and the cold water end of the pressure-bearing hot water tank respectively.

[0013] Preferably, a circulating pipeline is arranged between the outlet and the inlet of the high-temperature water heat storage and heat exchange device, and the circulating pipeline is located before the inlet of the pressure-bearing hot water tank.

[0014] Preferably, the steam extraction and heat recovery system is further connected with the cold water end of the pressure-bearing hot water tank.

[0015] Preferably, the steam extraction and heat recovery system comprises a shaft seal heater, a plurality of low-pressure heaters and a deaerator which are connected in sequence.

[0016] The outlet of the shaft seal heater is connected with the cold water end of the pressure-bearing hot water tank, and the inlet of the shaft seal heater is connected with the condenser of the thermal power generating unit.

[0017] Preferably, the steam extraction and heat recovery system comprises four low-pressure heaters which are connected in sequence.

[0018] The application further discloses a thermal power generating unit comprising the heat storage and heat exchange device.

[0019] Compared with the prior art, the application has the following beneficial technical effects:

[0020] The application discloses a thermal power unit energy storage heat exchange device, which comprises a steam extraction heat recovery system, a molten salt energy storage heat exchange system and a high-temperature water energy storage heat exchange system; the molten salt energy storage heat exchange system comprises a molten salt heat storage heat exchanger, and the high-temperature water energy storage heat exchange system comprises a high-temperature water heat storage heat exchanger; meanwhile, the inlet of the molten salt heat storage heat exchanger is connected with the outlet of a reheater of the thermal power unit, the outlet of the molten salt heat storage heat exchanger is connected with the inlet of the high-temperature water heat storage heat exchanger, and the outlet of the high-temperature water heat storage heat exchanger is connected with the steam extraction heat recovery system. In the device, the thermal medium in the reheater of the thermal power unit sequentially passes through the molten salt heat storage heat exchanger and the high-temperature water heat storage heat exchanger, exchanges heat with the molten salt heat storage heat exchanger and the high-temperature water heat storage heat exchanger, stores heat in the molten salt energy storage heat exchange system and the high-temperature water energy storage heat exchange system, and the condensed cold medium returns to the steam extraction heat recovery system, so that the heat in the reheater steam is stored and recovered for use of other systems. The device effectively avoids that a large amount of high-temperature and high-pressure steam directly enters a condenser after temperature reduction and pressure reduction, thereby causing serious waste, and avoids heat load pressure on the condenser and the circulating water system, realizes effective energy utilization, and effectively prolongs the service life of the system.

[0021] Further, the steam extraction heat recovery system comprises a condenser; the outlet of the reheater of the thermal power unit is also connected with the condenser in an on-off mode, so that the pressure of the reheater can be effectively controlled and ensured to be within a normal range.

[0022] Further, the molten salt energy storage heat exchange system further comprises a molten salt heat release heat exchanger, the inlet and the outlet of the molten salt heat release heat exchanger are connected with the steam extraction heat recovery system, so that the cold medium in the steam extraction heat recovery system is heated after heat exchange with the molten salt heat release heat exchanger, the heated thermal medium is obtained, and the cold medium in the steam extraction heat recovery system is heated and the stored heat in the molten salt energy storage heat exchange system is effectively utilized.

[0023] Further, the high-temperature water energy storage heat exchange system further comprises a high-temperature water heat release heat exchanger, the inlet and the outlet of the high-temperature water heat release heat exchanger are connected with the steam extraction heat recovery system, so that the cold medium in the steam extraction heat recovery system is heated after heat exchange with the high-temperature water heat release heat exchanger, the heated thermal medium is obtained, and the cold medium in the steam extraction heat recovery system is heated and the stored heat in the high-temperature water energy storage heat exchange system is effectively utilized.

[0024] Further, the high-temperature water energy storage heat exchange system further comprises a pressure-bearing hot water tank, the high-temperature water heat storage heat exchanger and the high-temperature water heat release heat exchanger are connected with the hot water end and the cold water end of the pressure-bearing hot water tank respectively, and effective heat storage is realized.

[0025] Further, the high-temperature water heat storage heat exchanger is further provided with a circulating pipeline between the outlet and the inlet, the circulating pipeline is located before the inlet of the pressure-bearing hot water tank, so that the hot water reaches the set temperature when entering the pressure-bearing hot water tank.

[0026] Further, the steam extraction regenerative system is further connected with the cold water end of the pressure-bearing hot water tank, so that the cold water in the steam extraction regenerative system directly enters the pressure-bearing hot water tank and is used by the high-temperature water heat storage heat exchanger.

[0027] Further, the steam extraction regenerative system comprises a shaft seal heater, a plurality of low-pressure heaters and a deaerator which are connected in sequence, the outlet of the shaft seal heater is connected with the cold water end of the pressure-bearing hot water tank, and the inlet of the shaft seal heater is connected with the condenser of the thermal power generating unit, a plurality of low-pressure heaters which are connected in sequence can improve the temperature of the feed water, reduce the heat transfer temperature difference of the heating surface of the boiler, thereby reducing the irreversible loss and improving the thermal efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of the drawings.

[0029] Figure 1 It is a structural schematic diagram of the energy storage heat exchange device for the thermal power generating unit in the present application.

[0030] Wherein: 1, reheat steam inlet control valve, 2, heat exchange steam control valve, 3, molten salt heat release heat exchanger water side outlet electric door, 4, molten salt heat release heat exchanger water side inlet electric door, 5, condensate water secondary heat exchange booster pump outlet electric door, 6, molten salt heat release heat exchanger water side bypass electric door, 7, No. 5 low pressure heater outlet electric door, 8, No. 5 low pressure heater inlet electric door, 9, hot water control valve, 10, cold water control valve, 11, hot water supply valve, 12, cold water supply valve, 13, unqualified high temperature water control valve, 14, qualified high temperature water control valve, 15, pressurized hot water tank circulating pump outlet valve, 16, water side heat release control valve, 17, water side heat storage control valve, 18, pressurized hot water tank water supply regulating valve, 19, condensate water primary heat exchange booster pump outlet electric door, 20, condensate water primary heat exchange control valve, 21, high temperature water heat storage heat exchanger drain pump outlet valve, 22, low pressure bypass valve, 23, molten salt heat storage heat exchanger, 24, molten salt heat release heat exchanger, 25, high temperature molten salt storage tank, 26, low temperature molten salt storage tank, 27, condensate water secondary heat exchange booster pump, 28, high temperature water heat release heat exchanger, 29, high temperature water heat storage heat exchanger, 30, condensate water primary heat exchange booster pump, 31, pressurized hot water tank circulating pump, 32, high temperature water heat storage heat exchanger drain pump, 33, pressurized hot water tank, 34, condenser, 35, condensate water pump, 36, shaft seal heater, 37, No. 8 low pressure heater, 38, No. 7 low pressure heater, 39, No. 6 low pressure heater, 40, No. 5 low pressure heater, 41, deaerator. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0033] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0034] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0035] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0036] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] The present application will be described in further detail below with reference to the accompanying drawings:

[0038] Embodiment 1

[0039] The present application discloses a thermal power unit energy storage heat exchange device, comprising a steam extraction regenerative system, a molten salt energy storage heat exchange system and a high-temperature water energy storage heat exchange system; the molten salt energy storage heat exchange system comprises a molten salt heat storage heat exchanger 23, and the high-temperature water energy storage heat exchange system comprises a high-temperature water heat storage heat exchanger 29; the inlet of the molten salt heat storage heat exchanger 23 is connected with the outlet of a reheater of a thermal power unit, the outlet of the molten salt heat storage heat exchanger 23 is connected with the inlet of the high-temperature water heat storage heat exchanger 29, and the outlet of the high-temperature water heat storage heat exchanger 29 is connected with the steam extraction regenerative system.

[0040] The hot working medium in the reheater of the thermal power unit in the device successively passes through the molten salt heat storage heat exchanger 23 and the high-temperature water heat storage heat exchanger 29, and after heat exchange with the molten salt heat storage heat exchanger 23 and the high-temperature water heat storage heat exchanger 29, stores heat in the molten salt heat storage system and the high-temperature water heat storage system, and the condensed cold working medium returns to the steam extraction heat recovery system, realizing storage and recovery of heat in the reheater steam, for use of other systems. The device effectively avoids the situation that a large amount of high-temperature and high-pressure steam directly enters the condenser after temperature reduction and pressure reduction, causing serious waste, and at the same time avoids the situation that the condenser and the circulating water system are subjected to thermal load pressure, realizing effective use of energy and effectively improving the service life of the system.

[0041] In addition, in order to stabilize the pressure of the system, in one preferred embodiment, the steam extraction heat recovery system comprises a condenser 34, and the outlet of the reheater of the thermal power unit is also in on-off connection with the condenser 34.

[0042] In addition, in one aspect of utilization of the stored heat, the cold working medium in the steam extraction heat recovery system is heated, that is, the molten salt heat storage system further comprises a molten salt heat release heat exchanger 24, and the inlet and outlet of the molten salt heat release heat exchanger 24 are connected with the steam extraction heat recovery system. Similarly, the high-temperature water heat storage system further comprises a high-temperature water heat release heat exchanger 28, and the inlet and outlet of the high-temperature water heat release heat exchanger 28 are connected with the steam extraction heat recovery system. Similarly, heating of the cold working medium in the steam extraction heat recovery system is realized. In a further preferred scheme, the cold working medium in the steam extraction heat recovery system can successively undergo heat exchange with the high-temperature water heat release heat exchanger 28 and the molten salt heat release heat exchanger 24, that is, the cold working medium in the steam extraction heat recovery system can be heated by at least one of the high-temperature water heat release heat exchanger 28 and the molten salt heat release heat exchanger 24.

[0043] In a further detailed scheme, the high-temperature water heat storage system further comprises a pressurized hot water tank 33, and the high-temperature water heat storage heat exchanger 29 and the high-temperature water heat release heat exchanger 28 are respectively connected with the hot water end and the cold water end of the pressurized hot water tank 33, effectively realizing storage and release of heat.

[0044] In a more preferred scheme, a circulating pipeline is further arranged between the outlet and the inlet of the high-temperature water heat storage heat exchanger 29, and the circulating pipeline is located before the inlet of the pressurized hot water tank 33, so that the temperature of the hot water entering the pressurized hot water tank 33 reaches a set requirement, satisfying system use.

[0045] In addition, in order to improve direct utilization of the cold water in the steam extraction heat recovery system, the steam extraction heat recovery system is further connected with the cold water end of the pressurized hot water tank 33.

[0046] In a further detailed scheme, the steam extraction regenerative system comprises a shaft seal heater 36, several low-pressure heaters and a deaerator 41 connected in sequence; the outlet of the shaft seal heater 36 is connected with the cold water end of the pressurized hot water tank 33; the inlet of the shaft seal heater 36 is connected with the condenser 34 of the thermal power generating unit, and the steam extraction regenerative system comprises four low-pressure heaters connected in sequence.

[0047] The energy storage and heat exchange of the thermal power generating unit can effectively optimize the FCB function of the thermal power generating unit.

[0048] Embodiment 2

[0049] In order to further explain the technical scheme of the present application, the following embodiments are used for illustration:

[0050] A system for optimizing the FCB function of a thermal power generating unit by using a molten salt energy storage and heat exchange device, i.e., the energy storage and heat exchange device of the thermal power generating unit, comprises a steam extraction regenerative system, a molten salt energy storage and heat exchange system and a high-temperature water energy storage and heat exchange system,

[0051] (I) Steam extraction regenerative system

[0052] The steam extraction regenerative system comprises a condenser 34, a condensate pump 35, a shaft seal heater 36, a No. 8 low-pressure heater 37, a No. 7 low-pressure heater 38, a No. 6 low-pressure heater 39, a No. 5 low-pressure heater 40, a deaerator 41 and a condensate pipe connected with each other. The main function of this system is to heat the condensate and feed water by recovering and utilizing part of the steam after doing work in the steam turbine, so as to improve the efficiency of the entire thermal cycle.

[0053] Among them, the condenser 34 is the cold source in the thermal cycle of the steam turbine, and its main function is to condense the steam discharged by the steam turbine into water for recycling. At the same time, it also provides a vacuum environment to make the steam expand at low pressure, thereby improving the thermal efficiency.

[0054] The condensate pump 35 is responsible for pumping the condensate in the condenser and sending it to the shaft seal heater and the low-pressure heaters at each stage for heating.

[0055] The shaft seal heater 36, also known as the shaft seal cooler, is used to recover the steam leakage of the steam turbine shaft seal system and heat the condensate or desalted water by using the heat. This helps to reduce energy loss and improve the thermal efficiency of the unit. Among them, the turbine shaft seal system is mainly used to isolate the outside air from the steam turbine and reduce the leakage of steam. The system is usually composed of two parts: a shaft seal steam supply system and a steam return system. The steam supply system generally operates in a way that the steam discharged from the high-pressure cylinder and the medium-pressure cylinder is cooled and then supplied to the low-pressure cylinder for use, while the steam return system recovers the mixture discharged from the last end of the low-pressure cylinder, the medium-pressure cylinder and the high-pressure cylinder into the condenser.

[0056] No. 8 low pressure heater 37, No. 7 low pressure heater 38, No. 6 low pressure heater 39, No. 5 low pressure heater 40: The low pressure heaters here are the low pressure heaters, which use part of the steam in the steam turbine to heat the condensed water and feed water. By heating step by step, the temperature of the feed water can be increased, the temperature difference of the heat transfer surface of the boiler can be reduced, and thus the irreversible loss can be reduced and the thermal efficiency can be improved.

[0057] Deaerator 41: The deaerator is used to remove dissolved oxygen and other non-condensable gases in the feed water to prevent corrosion and oxidation. At the same time, it is also an important link in the process of heating the feed water, further increasing the temperature of the feed water.

[0058] (II) Molten salt storage and heat exchange system

[0059] The molten salt storage and heat exchange system includes a high-temperature molten salt storage tank 25, a molten salt heat-releasing heat exchanger 24, a low-temperature molten salt storage tank 26, and a molten salt heat storage heat exchanger 23.

[0060] Among them, the high-temperature molten salt storage tank 25: for storing a large amount of heat energy of the molten salt after heating and storage. These molten salts can be transported to the heat-releasing heat exchanger through pipelines when needed.

[0061] Molten salt heat-releasing heat exchanger 24: In the molten salt heat-releasing heat exchanger 24, the high-temperature molten salt exchanges heat with a certain working fluid, such as steam or water, and the molten salt releases its stored heat energy to heat the working fluid, thereby generating steam or hot water for driving the turbine to generate electricity or for other heat energy utilization.

[0062] Low-temperature molten salt storage tank 26: After the heat-releasing process, the temperature of the molten salt will decrease. These molten salts are collected in the low-temperature molten salt storage tank, waiting for the next heating and energy storage process.

[0063] Molten salt heat storage heat exchanger 23: This is the key component of heat storage, the heat from the reheated steam heats the molten salt and stores it. In the FCB (fast cut back) or other conditions requiring rapid response, these stored heat energy can be quickly utilized.

[0064] Because the molten salt will solidify at low temperature, it is necessary to install electric heat tracing equipment on the pipeline to ensure that the molten salt remains in a liquid state during transportation. Electric heat tracing can provide the necessary heat to prevent the molten salt from solidifying and clogging the pipeline. Therefore, the high-temperature molten salt storage tank 25, the molten salt heat-releasing heat exchanger 24, the low-temperature molten salt storage tank 26, and the molten salt heat storage heat exchanger 23 are connected by pipelines with electric heat tracing.

[0065] The working principle of the entire molten salt heat storage and exchange system is as follows: in the heat storage working condition, the low-temperature molten salt in the low-temperature molten salt storage tank 26 enters the molten salt heat storage and exchange device 23 through a molten salt pump to absorb heat from the reheated steam, the high-temperature molten salt after heat absorption enters the high-temperature molten salt storage tank 25, and the heat storage process is completed. In the heat release working condition, the high-temperature molten salt in the high-temperature molten salt storage tank 25 enters the molten salt heat release and exchange device 24 through a molten salt pump to release heat to the condensed water, the low-temperature molten salt after heat release enters the low-temperature molten salt storage tank 26, and the heat release process is completed.

[0066] In addition, a reheated steam inlet control valve 1 is arranged at the steam side inlet of the molten salt heat storage and exchange device 23, and a heat-exchanged steam control valve 2 is arranged at the steam side outlet of the molten salt heat storage and exchange device 23. The steam-water mixture generated after the reheated steam is exchanged by the molten salt heat storage and exchange device 23 still has a relatively high temperature, and in the present application, the heat is transferred to the high-temperature water in the upper layer of the pressurized hot water tank 33 through the high-temperature water heat storage and exchange device 29, and the heat-exchanged drain water is recovered to the No. 6 low-pressure heater outlet through the high-temperature water heat storage and exchange device drain pump 32 and the control valve 21 at the pump outlet.

[0067] Here, the reheated steam inlet control valve 1 is arranged at the steam side inlet of the molten salt heat storage and exchange device 23, and is used to control the flow of the reheated steam entering the molten salt heat storage and exchange device 23. By adjusting the control valve, the amount of steam entering the heat exchanger can be controlled, thereby controlling the heat load of the heat exchanger.

[0068] The heat-exchanged steam control valve 2 is arranged at the steam side outlet of the molten salt heat storage and exchange device 23, and is used to control the steam leaving the heat exchanger, which may be a steam-water mixture at this time. By adjusting this control valve, the outlet pressure and temperature of the steam can be controlled. The steam-water mixture still has a relatively high temperature because the steam released part of the heat to the molten salt during the heat exchange process, but the temperature of the steam itself is still very high. The steam-water mixture enters the high-temperature water heat storage and exchange device 29 to transfer the remaining heat to the high-temperature water in the upper layer of the pressurized hot water tank 33. This process further reduces the temperature of the steam, causing it to be converted into drain water, i.e. liquid water. The heat-exchanged drain water, i.e. liquid water, is recovered to the No. 6 low-pressure heater outlet through the high-temperature water heat storage and exchange device drain pump 32 and the control valve 21 at the pump outlet. This process realizes the recovery and reuse of heat, improving the thermal efficiency of the entire system.

[0069] The pressurized hot water tank 33 is a container for storing high-temperature water, which receives heat from the steam-water mixture through the high-temperature water heat storage and exchange device 29 to increase the temperature of the water in the upper layer.

[0070] The workflow of the above system is as follows: the reheated steam enters the molten salt heat storage heat exchanger 23 through the control valve 1, exchanges heat with the molten salt, and the steam temperature decreases to become a steam-water mixture. The steam-water mixture enters the high-temperature water heat storage heat exchanger 29, transfers the remaining heat to the high-temperature water in the pressurized hot water tank 33, and then is converted into steam. The steam is recovered to the No. 6 low-pressure heater outlet through the high-temperature water heat storage heat exchanger steam pump 32 and the control valve 21, completing the entire heat exchange and recovery process.

[0071] The reheater of the thermal power unit and the condenser of the thermal power unit are set to be on-off, that is, a low-pressure bypass valve 22 is arranged between the reheater and the condenser. In the FCB working condition, most of the reheated steam enters the molten salt heat storage heat exchanger 23 through the reheated steam inlet control valve 1 for heat exchange. In the FCB working condition, due to the rapid change of load, the pressure of the reheater may fluctuate. At this time, the low-pressure bypass valve 22 plays a key role. Its main function is to control the pressure of the reheater to ensure its operation within the normal range. When the pressure of the reheater is too high, the low-pressure bypass valve 22 will quickly open to guide part of the steam to other systems or equipment, thereby reducing the pressure of the reheater and preventing it from exceeding the safety limit. The regulation function of the low-pressure bypass valve 22 is crucial for maintaining the stable operation of the unit. It not only can quickly respond to pressure changes, but also can accurately adjust according to the actual situation of the system to ensure the normal operation of the reheater and other key equipment. In addition, the low-pressure bypass valve 22 can quickly switch to the standby system when the main system fails or needs maintenance, ensuring the continuity and stability of power supply. The design aims to effectively utilize and store heat energy, improving the overall efficiency of the unit. The molten salt heat storage heat exchanger 23 also plays an important role in the FCB working condition. It uses the heat capacity of molten salt to store heat energy and release heat energy when needed to drive the steam turbine to generate electricity. This technology not only improves energy utilization efficiency, but also helps to balance the load of the power grid, improving the stability and reliability of the power system. In the FCB working condition, the low-pressure bypass valve 22 and the molten salt heat storage heat exchanger 23 work together to ensure the stable operation of the unit and efficient energy conversion.

[0072] (Three) High-temperature water storage heat exchange system

[0073] For the high-temperature water storage and heat exchange system, the system includes a pressurized hot water tank 33, the upper part of the pressurized hot water tank 33 is connected with a hot water control valve 9, and the lower part of the pressurized hot water tank 33 is connected with a cold water control valve 10. The outlet of the hot water control valve 9 is connected with a hot water supply valve 11, and the outlet of the cold water control valve 10 is connected with a cold water supply valve 12. The outlet of the hot water supply valve 11 and the outlet of the cold water supply valve 12 are connected with the same mother pipe, the mother pipe is connected with a pressurized hot water tank circulating pump 31, the outlet of the pressurized hot water tank circulating pump 31 is connected with a pressurized hot water tank circulating pump outlet valve 15, and the pressurized hot water tank circulating pump outlet valve 15 is respectively connected with a water side heat storage control valve 17 and a water side heat release control valve 16. The water side heat storage control valve 17 is connected with a high-temperature water storage and heat exchange device 29, and the circulating water after heat exchange and temperature rise is connected with a qualified high-temperature water control valve 14 and then is connected with a pipeline between the hot water control valve 9 and the hot water supply valve 11. The water side heat release control valve 16 is connected with a high-temperature water heat release and heat exchange device 28, and the circulating water after heat exchange and temperature drop is connected with a pipeline between the cold water control valve 10 and the cold water supply valve 12.

[0074] The pressurized hot water tank 33 in the above system is used as the main container for storing high-temperature water. The hot water control valve 9 is used to control the outflow of high-temperature water in the upper part of the pressurized hot water tank 33. The cold water control valve 10 is used to control the outflow of cold water in the lower part of the pressurized hot water tank 33. The hot water supply valve 11 and the cold water supply valve 12 are respectively used to adjust the flow of high-temperature water and cold water. The pressurized hot water tank circulating pump 31 is used to circulate the water in the pressurized hot water tank 33, so as to keep the water temperature and pressure stable. The pressurized hot water tank circulating pump outlet valve 15 is used to control the water flow at the outlet of the circulating pump. The water side heat storage control valve 17 and the water side heat release control valve 16 are respectively used to control the flow of circulating water to the heat storage and heat exchange device and the heat release and heat exchange device. The high-temperature water storage and heat exchange device 29 is used to heat the circulating water by using an external heat source, such as steam, molten salt, etc. The high-temperature water heat release and heat exchange device 28 is used to release the heat in the circulating water to an external system or environment, so as to reduce the water temperature. The qualified high-temperature water control valve 14 is used to ensure that the circulating water after heat exchange and temperature rise meets the quality requirements of high-temperature water, and then is connected to the hot water system.

[0075] The working process of the high-temperature water storage and heat exchange system includes:

[0076] (1) Hot water circulation: when the system needs high-temperature water, the hot water control valve 9 is opened, the pressurized hot water tank 31 is started, and the circulating pump pumps out the water in the pressurized hot water tank 33 and supplies it to the system or equipment that needs high-temperature water through the hot water supply valve 11.

[0077] (2) Heat storage process: when there is excess heat in the external heat source (such as steam, molten salt, etc.), the pressurized hot water tank circulating pump 31 sends the circulating water to the high-temperature water storage and heat exchange device 29 through the water side heat storage control valve 17, and exchanges heat with the heat source to increase the water temperature. The high-temperature water after heat exchange is returned to the upper part of the pressurized hot water tank 33 through the qualified high-temperature water control valve 14.

[0078] (3) Heat releasing process: When the system needs to be cooled or needs to release heat from the pressurized hot water tank 33, the pressurized hot water tank circulating pump 31 sends the circulating water through the water side heat releasing control valve 16 into the high temperature water heat releasing heat exchanger 28, exchanges heat with the external system or environment, and lowers the water temperature. The cooled water after heat exchange returns to the lower part of the pressurized hot water tank 33.

[0079] (4) Cold water circulation: When the system needs cold water, the cold water control valve 10 is opened, and the cold water supply valve 12 adjusts the flow to supply the cold water from the lower part of the pressurized hot water tank 33 to the system or equipment that needs cold water. The whole system realizes the storage, heating, cooling and supply of high temperature water by controlling the opening and closing and adjusting of each valve, so as to meet the demand of different systems or equipment for water temperature.

[0080] In the above-mentioned high temperature water storage and heat exchange system, the water side outlet of the pressurized water tank heat storage heat exchanger 29 is connected with the qualified high temperature water control valve 14 and the unqualified high temperature water control valve 13 respectively. In the heat storage mode, at the initial stage of starting the pressurized hot water tank circulating pump 31, the circulating water temperature through the pressurized water tank heat storage heat exchanger 29 has not yet reached the standard for recycling to the pressurized hot water tank (≥95℃), at this time it is returned to the circulating pump inlet through the unqualified high temperature water control valve 13, and when the circulating water temperature reaches the required temperature, the qualified high temperature water control valve 14 is opened and the unqualified high temperature water control valve 13 is closed, so that only the circulating water that meets the temperature requirement is recycled. The heated circulating water is pumped to the upper part of the pressurized hot water tank through the qualified high temperature water control valve 14. In this way, the water temperature in the pressurized hot water tank gradually rises, preparing for the subsequent hot water supply.

[0081] The above-mentioned steam extraction heat recovery system is connected with the high temperature water storage and heat exchange system, which realizes the heating of the condensate water in the steam extraction heat recovery system by using the high temperature water storage and heat exchange system. The molten salt storage and heat exchange system is connected with the steam extraction heat recovery system and the high temperature water storage and heat exchange system, realizing the transfer of heat from the molten salt storage and heat exchange system to the condensate water in the steam extraction heat recovery system and the cold water in the high temperature water storage and heat exchange system, so as to raise the temperature of the corresponding cold working medium.

[0082] A condensate primary heat exchange booster pump 30, a condensate primary heat exchange booster pump outlet motorized gate 19, a condensate primary heat exchange control valve 20, and a pressurized hot water tank water supplement regulating valve 18 are provided between the steam extraction regenerative system and the high-temperature water storage heat exchange system. The outlet of the shaft seal heater 36 in the steam extraction regenerative system is connected to the condensate primary heat exchange booster pump 30 and the pressurized hot water tank water supplement regulating valve 18. The outlet of the condensate primary heat exchange booster pump 30 is connected to the condensate primary heat exchange booster pump outlet motorized gate 19. The condensate primary heat exchange booster pump outlet motorized gate 19 is connected to the high-temperature water heat release heat exchanger 28. The condensate water heated by the high-temperature water heat release heat exchanger 28 is collected into the outlet of the No. 6 low-pressure heater 39 in the steam extraction regenerative system through the condensate primary heat exchange control valve 20. This part is mainly used to heat the condensate water through the high-temperature water heat release heat exchanger 28 and recycle the heated condensate water into the system. The specific process is as follows:

[0083] (1) Condensate source:

[0084] The outlet of the shaft seal heater 36 is the source of the condensate water. The shaft seal heater 36 is used to recover the condensate water in the shaft seal steam and may preliminarily increase the temperature of the condensate water through its heating action.

[0085] (2) Condensate pressurization:

[0086] The condensate water flows from the outlet of the shaft seal heater 36 into the condensate primary heat exchange booster pump 30. The condensate primary heat exchange booster pump 30 pressurizes the condensate water to ensure that it can overcome the resistance in the system and flow smoothly.

[0087] (3) Flow to the heat release heat exchanger:

[0088] The pressurized condensate water flows out through the condensate primary heat exchange booster pump outlet motorized gate 19. The condensate primary heat exchange booster pump outlet motorized gate 19 controls the flow of the condensate water to ensure that it can enter the high-temperature water heat release heat exchanger 28 when needed.

[0089] (4) Heating in the heat release heat exchanger:

[0090] The condensate water exchanges heat with the heat source, i.e., hot water, in the high-temperature water heat release heat exchanger 28, thereby heating the condensate water.

[0091] (5) Condensate recovery:

[0092] The heated condensate water adjusts its flow through the condensate primary heat exchange control valve 20. Subsequently, the heated condensate water is collected into the outlet of the No. 6 low-pressure heater, ready to be recycled into the condensate water system.

[0093] Through the above system, effective heating and recycling of the condensate water can be achieved, improving the thermal efficiency and economy of the system.

[0094] A first heat exchange system is provided between the steam extraction regenerative system and the molten salt heat storage and exchange system. The first heat exchange system includes a low-pressure heater outlet gate valve 7, a condensate secondary heat exchange booster pump 27, a condensate secondary heat exchange booster pump outlet gate valve 5, a molten salt heat release heat exchanger water side inlet gate valve 4, and a molten salt heat release heat exchanger water side outlet gate valve 3 arranged in sequence between the No. 5 low-pressure heater 40 outlet and the deaerator 41. The cold working medium flowing through the first heat exchange system is finally introduced into the deaerator 41 after heat exchange in the molten salt heat release heat exchanger 24. In addition, a low-pressure heater inlet gate valve 8 is further provided between the No. 5 low-pressure heater 40 inlet and the condensate secondary heat exchange booster pump 27, and a molten salt heat release heat exchanger water side bypass gate valve 6 is further provided between the outlet of the condensate secondary heat exchange booster pump outlet gate valve 5 and the outlet of the molten salt heat release heat exchanger water side outlet gate valve 3.

[0095] That is, the inlet and outlet of the No. 5 low-pressure heater 40 are respectively provided with a No. 5 low-pressure heater inlet gate valve 8 and a No. 5 low-pressure heater outlet gate valve 7. The outlet pipelines of the No. 5 low-pressure heater inlet gate valve 8 and the No. 5 low-pressure heater outlet gate valve 7 are connected to the inlet of the condensate secondary heat exchange booster pump 27. The condensate secondary heat exchange booster pump 27 is connected to the condensate secondary heat exchange booster pump outlet gate valve 5. The condensate secondary heat exchange booster pump outlet gate valve 5 is connected to the molten salt heat release heat exchanger water side inlet gate valve 4 and the molten salt heat release heat exchanger water side bypass gate valve 6. The cold working medium flowing through the molten salt heat release heat exchanger water side inlet gate valve 4 is heat-exchanged in the molten salt heat release heat exchanger 24, and then flows to the deaerator 41 through the molten salt heat release heat exchanger water side outlet gate valve 3. That is, the condensate water heated by the molten salt heat release heat exchanger is connected to the deaerator 41 through the condensate pipeline. This part mainly relates to the heating process of the condensate water in the molten salt heat release heat exchanger. The specific process is as follows:

[0096] (1) Condensate water inflow:

[0097] The No. 5 low-pressure heater inlet gate valve 8 controls the inlet of the No. 5 low-pressure heater, allowing the condensate water to flow in.

[0098] The No. 5 low-pressure heater outlet gate valve 7 controls the condensate water flowing out of the No. 5 low-pressure heater and guides it to the inlet of the condensate secondary heat exchange booster pump 27.

[0099] (2) Condensate water pressurization:

[0100] The condensate secondary heat exchange booster pump 27 pressurizes the condensate water to overcome the resistance in the system and push it to the subsequent heat exchanger.

[0101] (3) Flow to the molten salt heat release heat exchanger:

[0102] The pressurized condensate water flows out through the outlet motorized gate 5 of the condensate secondary heat exchange pressurizing pump. The outlet motorized gate 5 controls the flow of the condensate water to ensure that it can enter the molten salt heat releasing heat exchanger according to the system requirements. The condensate water can be selected to enter the molten salt heat releasing heat exchanger water side inlet motorized gate 4 or directly pass through the molten salt heat releasing heat exchanger water side bypass motorized gate 6 (when heating is not required).

[0103] (4) Heating in the molten salt heat releasing heat exchanger:

[0104] When the motorized gate 4 is opened and the motorized gate 6 is closed, the condensate water flows into the molten salt heat releasing heat exchanger. Here, the condensate water exchanges heat with the molten salt, thereby being heated.

[0105] (5) Condensate water outflow and recovery:

[0106] The heated condensate water flows out through the molten salt heat releasing heat exchanger water side outlet motorized gate 3. The molten salt heat releasing heat exchanger water side outlet motorized gate 3 controls the flow of the heated condensate water to ensure that it can flow out smoothly. The heated condensate water is collected through the condensate pipe to the deaerator 41, ready for further processing or used in other parts of the system.

[0107] Meanwhile, the application also discloses a thermal power generating unit comprising the energy storage heat exchange device.

[0108] Example 3

[0109] The operation method of the system for optimizing the FCB function of the thermal power generating unit by using the molten salt energy storage heat exchange device in Example 2 comprises the following steps:

[0110] 1. The heat storage part after the FCB action of the thermal power generating unit

[0111] 1.1 After the FCB signal of the unit is triggered, the generator grid-connected switch is disconnected with plant power operation, the unit is thrown off most of the load, the high-pressure bypass quick opening, the reheating steam inlet control valve 1 quick opening, the low-pressure bypass valve 22 controls the reheater pressure and the condenser heat load to prevent the reheater from overpressure and the condenser from overloading. The molten salt heat storage circuit is started after the FCB signal is triggered, all low-temperature molten salt delivery pumps are started, and the frequency is full.

[0112] 1.2 After the first heat exchange of the reheat steam through the molten salt heat storage heat exchanger 23, the steam still has a high temperature. After the FCB signal is triggered, the pressurized hot water tank storage heat exchange system is switched to the heat storage mode, the cold water control valve 10, the cold water supply valve 12, the water side heat storage control valve 17, the unqualified high temperature water control valve 13 and the hot water control valve 9 are opened, the hot water supply valve 11 and the water side heat release control valve 16 are closed, the pressurized hot water tank circulating pump 31 is started, and after the circulating pump is started, the pressurized hot water tank circulating pump outlet valve 15 is opened. When the outlet temperature of the pressurized water tank heat storage heat exchanger 29 reaches the recovery standard, the unqualified high temperature water control valve 13 is closed, the qualified high temperature water control valve 14 is opened, and the high temperature water is recovered to the upper part of the pressurized hot water tank.

[0113] 1.3 When the low temperature molten salt in the low temperature molten salt storage tank 26 is depleted or the cold water in the pressurized hot water tank 33 is depleted, the heat storage should be stopped, at this time the unit has entered the energy balance state of the working medium, and the front pressure and the reheater pressure can be well controlled through the high and low bypass.

[0114] 2. Heat release part after the unit is reconnected to the grid

[0115] 2.1 After the unit is reconnected to the grid with load, in order to save the coal consumption of power generation and realize energy-saving operation of the unit, the storage heat exchange system is switched to the heat release mode. The condensate water primary heat exchange booster pump 30 is started, the condensate water primary heat exchange booster pump outlet electric door 19 is opened, the condensate water enters the pressurized water tank heat release heat exchanger, i.e. the high temperature water heat release heat exchanger 28, and after heat exchange, enters the No. 6 low pressure heater outlet. After the pressurized hot water tank storage heat exchange system is switched to the heat storage mode, the hot water supply valve 11, the cold water control valve 10, the hot water control valve 9 and the water side heat release control valve 16 are opened, the water side heat storage control valve 17, the unqualified high temperature water control valve 13 and the qualified high temperature water control valve 14 are closed, the pressurized hot water tank circulating pump 31 is started, and after the circulating pump is started, the pressurized hot water tank circulating pump outlet valve 15 is opened. The high temperature water of the pressurized hot water tank is released through the pressurized water tank heat release heat exchanger and then recovered to the bottom of the pressurized hot water tank.

[0116] 2.2 At the No. 5 low pressure heater 40 inlet and outlet, the condensate water after the first heating enters the condensate water secondary heat exchange booster pump 27 through the No. 5 low pressure heater inlet electric door 8 or the No. 5 low pressure heater outlet electric door 7. The condensate water secondary heat exchange booster pump 27 is started, the condensate water secondary heat exchange booster pump outlet electric door 5 is opened, and by adjusting the condensate water amount through the main path and bypass of the molten salt heat release heat exchanger 24, the condensate water temperature entering the deaerator is controlled.

[0117] 2.3 When the high temperature molten salt in the high temperature molten salt storage tank 25 is depleted or the hot water in the pressurized hot water tank 33 is depleted, the heat release should be stopped. When the unit enters the low load deep regulation operating condition, the heat storage is performed again.

[0118] The application improves the stability and reliability of the FCB process of the thermal power generating unit, reduces the operation cost of the unit, and enhances the resistance of the unit to external risks and the degree of energy cascade utilization by fully recycling the high-quality heat energy released by the unit due to rapid load reduction in the FCB condition. The system operation mode proposed by the application can realize the suppression of the large fluctuation of the steam-water system on the boiler side of the steam turbine during the FCB operation, reduce the difficulty of high-low side regulation, avoid the operation of the condenser under the excess rated heat load, and recover a large amount of high-quality heat energy released during the drastic change of the FCB condition of the unit. The system operation mode proposed by the application is not only suitable for the extreme condition of FCB, but also suitable for the daily peak regulation operation of the unit. In the deep regulation stage of the unit, the reheat steam heat energy generated by the boiler can be stored in stages. In the large load stage of the unit, the heat stored in the high-temperature water and the molten salt can be extracted and used in stages, the extraction amount of the steam in the regenerative system is reduced, and the peak capacity of the unit is improved. The heat storage and exchange system combining the molten salt and the high-temperature water can realize the functions of both flat and urgent use. When the power grid fails and the unit needs to operate in an isolated grid, it is the spark for restoring the power grid. In the daily peak regulation operation, it is an effective means to improve the deep regulation capacity and economy of the unit. The application is suitable for the thermal power generating unit using the molten salt and the high-temperature water as the heat storage and exchange medium, and has the universal conditions for popularization.

[0119] The above is only the preferred embodiment of the application, and is not used to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A thermal power unit energy storage heat exchange device, characterized in that, The system comprises a steam extraction regenerative system, a molten salt storage and heat exchange system, and a high-temperature water storage and heat exchange system. The molten salt storage and heat exchange system comprises a high-temperature molten salt storage tank (25), a molten salt heat-releasing heat exchanger (24), a low-temperature molten salt storage tank (26), and a molten salt heat storage heat exchanger (23) connected in sequence. The high-temperature water storage and heat exchange system comprises a high-temperature water heat-releasing heat exchanger (28), a high-temperature water heat storage heat exchanger (29), and a pressurized hot water tank (33); the high-temperature water heat-releasing heat exchanger (28) is arranged in an on-off manner with the cold water end of the pressurized hot water tank (33), and the high-temperature water heat storage heat exchanger (29) is arranged in an on-off manner with the hot water end of the pressurized hot water tank (33). The inlet of the molten salt heat storage heat exchanger (23) is connected with the outlet of the reheater of the thermal power generating unit, the outlet of the molten salt heat storage heat exchanger (23) is connected with the inlet of the high-temperature water heat storage heat exchanger (29), and the outlet of the high-temperature water heat storage heat exchanger (29) is connected with the steam extraction regenerative system. The steam extraction regenerative system comprises a condenser (34); a low-pressure bypass valve (22) is arranged between the reheater of the thermal power generating unit and the condenser (34) of the thermal power generating unit.

2. The energy storage and heat exchange device for a thermal power generating unit according to claim 1, characterized in that, The inlet and outlet of the molten salt heat-releasing heat exchanger (24) are both connected with the steam extraction regenerative system.

3. The energy storage and heat exchange device for a thermal power generating unit according to claim 1, characterized in that, The inlet and outlet of the high-temperature water heat-releasing heat exchanger (28) are both connected with the steam extraction regenerative system.

4. The energy storage and heat exchange device for thermal power generating unit according to claim 1, characterized in that, A circulating pipeline is arranged between the outlet and the inlet of the high-temperature water heat storage heat exchanger (29), and the circulating pipeline is located before the inlet of the pressurized hot water tank (33).

5. The energy storage and heat exchange device of a thermal power generating unit according to claim 1, characterized in that, The steam extraction regenerative system is also connected with the cold water end of the pressurized hot water tank (33).

6. The energy storage and heat exchange device of a thermal power generating unit according to claim 1, characterized in that, The steam extraction regenerative system comprises a shaft seal heater (36), a plurality of low-pressure heaters, and a deaerator (41) connected in sequence. The outlet of the shaft seal heater (36) is connected with the cold water end of the pressurized hot water tank (33), and the inlet of the shaft seal heater (36) is connected with the condenser (34) of the thermal power generating unit.

7. The energy storage and heat exchange device of a thermal power generating unit according to claim 1, characterized in that, The steam extraction regenerative system comprises four low-pressure heaters connected in sequence.

8. A thermal power unit, characterized in that The thermal power generating unit storage and heat exchange device comprises the device according to any one of claims 1-7.

Images