Air source steam heat pump system with fused salt heat storage and control method

Abstract

The invention discloses a steam heat pump system with fused salt heat storage and a control method. The steam heat pump system comprises a steam generation module used for converting water into steam; the heat pump is used for absorbing heat from the environment in the electricity utilization trough period and outputting heat to the steam generation module; the fused salt energy storage module is used for heating fused salt for energy storage in the electricity consumption trough period; the heat supply module is used for supplying heat to the steam generation module in a power limiting or power utilization peak period; the controller is electrically connected with the heat pump and the fused salt energy storage module and used for controlling the heat pump and the fused salt energy storage module to provide heat for the steam generation module. According to the steam heat pump system with the fused salt heat storage function and the control method, cost rise caused by electricity limitation or peak and valley electricity is avoided, stable supply of steam in the electricity limitation state is guaranteed, and the flexibility and stability of the system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of steam generation, and in particular to an air source steam heat pump system with molten salt heat storage and a control method. Background Art

[0002] As an important energy conversion and utilization device, steam heat pump system is widely used in food, medicine, chemical industry, textile and other industrial fields.

[0003] In many areas, the problem of industrial power curtailment during peak periods has become a bottleneck restricting the continuous operation of steam heat pump systems. Once power curtailment occurs, steam heat pumps will not be able to work properly, which will have an adverse impact on industrial production. At the same time, with the implementation of the peak-valley electricity price mechanism in the electricity market, the cost of electricity during peak hours has increased significantly, which undoubtedly increases the operating costs of enterprises. To address this problem, enterprises generally adopt thermal energy storage methods that burn fossil fuels.

[0004] However, this method has large heat loss and high operating cost. The present invention proposes a steam heat pump system with molten salt heat storage and a control method. By introducing molten salt heat storage technology, the energy storage efficiency of the system is improved, heat loss and cost are reduced, and a more efficient and stable steam heat pump system is realized. Summary of the invention

[0005] The present invention provides an air source steam heat pump system with molten salt heat storage and a control method to solve the problems that the traditional steam heat pump system cannot be operated during power cuts or peak power consumption periods or has high operating costs.

[0006] According to one aspect of the present invention, there is provided an air source steam heat pump system with molten salt heat storage, comprising: a steam generation module, for converting water into water vapor; a heat pump, for absorbing heat from the environment during off-peak hours and outputting heat to the steam generation module; a molten salt energy storage module, for heating the molten salt energy storage during off-peak hours; and for providing heat to the steam generation module during power cuts or peak hours; and a controller, respectively electrically connected to the heat pump and the molten salt energy storage module, for controlling the heat pump and the molten salt energy storage module to provide heat to the steam generation module.

[0007] Optionally, the heat pump includes at least one stage of sub-heat pump, which includes an evaporator, a compressor, a condenser and an expansion valve connected in sequence; the evaporator absorbs heat from the environment through a heat exchange process; the compressor is connected between the outlet of the evaporator and the inlet of the condenser, and is used to compress the heat absorbed by the evaporator and the low-temperature and low-pressure steam generated by the evaporation process into high-temperature and high-pressure steam; the condenser is connected between the outlet of the compressor and the inlet of the expansion valve, and is used to release the heat in the high-temperature and high-pressure steam output by the compressor to the outside through a heat exchange process; the expansion valve is connected between the outlet of the condenser and the inlet of the evaporator, and is used to reduce the temperature and pressure of the steam so as to reabsorb heat in the evaporator.

[0008] Optionally, the heat pump includes a primary heat pump and a secondary heat pump; the primary heat pump includes an evaporator of the primary heat pump, a compressor of the primary heat pump, a condenser of the primary heat pump and an expansion valve of the primary heat pump connected in sequence, and the condenser of the primary heat pump in the primary heat pump is directly connected to the evaporator of the secondary heat pump or is connected through a heat exchanger to use the heat released in the condenser of the primary heat pump as a heat source for the evaporator of the secondary heat pump; the secondary heat pump includes an evaporator of the secondary heat pump, a compressor of the secondary heat pump, a condenser of the secondary heat pump and an expansion valve of the secondary heat pump connected in sequence, and the condenser of the secondary heat pump provides heat to the steam generating module through a heat exchanger or a direct connection.

[0009] Optionally, the molten salt energy storage module includes: a molten salt energy storage tank, used to store high-temperature molten salt as a heat energy carrier; a heater, arranged inside the molten salt energy storage tank, used to heat the molten salt to a predetermined temperature, or maintain the molten salt temperature; a circulating pump, connected to the molten salt energy storage tank through an input pipe, used to drive the heating working fluid to output the heat energy stored in the molten salt energy storage module to the outside.

[0010] Optionally, the steam generator includes a flash tank, which is used to flash softened water heated by a heat pump and / or a molten salt energy storage module to form micro-pressure steam.

[0011] Optionally, the steam generating module further includes a first output channel and / or a second output channel; the first output channel is connected to the flash tank for directly outputting low-pressure steam; the second output channel is connected to the flash tank and is provided with a compressor for pressurizing the low-pressure steam and outputting high-pressure steam.

[0012] Optionally, the steam heat pump system also includes a temperature regulation system, which includes a temperature sensor, a heat exchange medium pump, a medium inlet valve, a first heat exchanger, a second heat exchanger and a heat exchange valve; the temperature sensor is used to obtain the output temperature of the heat pump; the heat exchange medium pump is used to drive the circulation of the heat exchange medium in the system; the medium inlet valve is used to regulate the flow of external heat exchange medium into the temperature regulation system to meet different heat exchange requirements; the first heat exchanger is used to regulate the output temperature of the heat pump by exchanging heat with the circulating heat exchange medium; the second heat exchanger is used to heat the heat exchange medium using a heat source medium; the heat exchange valve is used to close when the output temperature of the heat pump is higher than the first temperature, so that the heat exchange medium lowers the output temperature of the heat pump through the first heat exchanger; and open when the output temperature of the heat pump is lower than the second temperature, so that the heat exchange medium is heated through the second heat exchanger and then increases the output temperature of the heat pump through the first heat exchanger.

[0013] Optionally, the heat pump, the molten salt energy storage module and the steam generation module perform heat exchange through a three-way pipe heat exchanger, and the heat pump and / or the molten salt energy storage module in the three-channel heat exchanger provide heat to the steam generation module.

[0014] According to another aspect of the present invention, there is provided a control method for an air source steam heat pump with molten salt heat storage, which is implemented based on the steam heat pump system with molten salt heat storage of any one of the first aspects, and the method comprises: during the period of low electricity consumption, controlling the heat pump to absorb heat from the environment to provide heat to the steam generation module, so that the steam generation module converts water into water vapor; during the period of low electricity consumption, controlling the molten salt energy storage module to heat the molten salt energy storage; during the period of power restriction or peak electricity consumption, controlling the heat pump to stop working, and controlling the molten salt energy storage module to provide heat to the steam generation module, so that the steam generation module converts water into water vapor.

[0015] Optionally, the steam heat pump system also includes a temperature regulation system, which includes a temperature sensor, a heat exchange medium pump, a medium inlet valve, a first heat exchanger, a second heat exchanger and a heat exchange valve; during periods of low electricity consumption, the heat pump is controlled to absorb heat from the environment to provide heat to the steam generation module, so that the steam generation module converts water into water vapor, and also includes: obtaining the output temperature of the heat pump through a temperature sensor; when the output temperature of the heat pump is higher than the first temperature, closing the heat exchange valve to allow the heat exchange medium to lower the output temperature of the heat pump through the first heat exchanger; when the output temperature of the heat pump is lower than the second temperature, opening the heat exchange valve to allow the heat exchange medium to be heated through the second heat exchanger and then through the first heat exchanger to increase the output temperature of the heat pump.

[0016] The air source steam heat pump system with molten salt heat storage provided by the embodiment of the present invention provides heat energy to the steam generation module through a heat pump and / or a molten salt energy storage module. During periods when the grid load is low and the electricity price is relatively cheap, electricity is consumed to use a heat pump for heating, and energy is stored through a molten salt energy storage module. When the grid load is too high or the electricity price is high, the molten salt energy storage module stores energy and releases heat, thereby avoiding the cost increase caused by power rationing or peak-valley electricity, ensuring a stable supply of steam under power rationing conditions, and improving the flexibility and stability of the system.

[0017] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0019] Figure 1 A schematic structural diagram of an air source steam heat pump system with molten salt heat storage provided in an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of the structure of a heat pump provided by an embodiment of the present invention;

[0021] Figure 3 A schematic structural diagram of an air source steam heat pump system with molten salt heat storage provided in an embodiment of the present invention;

[0022] Figure 4 A flow chart of a control method of an air source steam heat pump with molten salt heat storage provided by an embodiment of the present invention;

[0023] Figure 5 A schematic flow chart of a control method for an air source steam heat pump with molten salt heat storage provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0025] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] Figure 1 A schematic diagram of the structure of an air source steam heat pump system with molten salt heat storage provided by an embodiment of the present invention, Figure 2 A schematic diagram of the structure of a heat pump 20 provided in an embodiment of the present invention is shown in FIG. Figure 3 The schematic diagram of the structure of an air source steam heat pump system with molten salt heat storage provided by an embodiment of the present invention. Figure 1 As shown, the steam heat pump system includes: a steam generating module 10, which is used to convert water into water vapor; a heat pump 20, which is used to absorb heat from the environment during the off-peak period of electricity consumption and output heat to the steam generating module 10; a molten salt energy storage module 30, which is used to heat the molten salt energy storage during the off-peak period of electricity consumption; and provide heat to the steam generating module 10 during power cuts or peak periods; a controller 40, which is electrically connected to the heat pump 20 and the molten salt energy storage module, respectively, and is used to control the heat pump 20 and the molten salt energy storage module to provide heat to the steam generating module 10.

[0027] Among them, the steam generation module 10 can be understood as a device that can heat water and convert it into steam (such as a flash tank); the heat pump 20 can be understood as a device that can absorb heat from a low-temperature heat source and transfer it to a high-temperature heat source; the molten salt energy storage module 30 can be understood as a module that uses the high heat storage capacity and thermal stability of molten salt to store and release heat; the electricity off-peak period can be understood as a period when the grid load is low and the electricity price is cheaper; the power restriction or peak electricity consumption period can be understood as a period when the grid load is too high to restrict electricity consumption or the electricity price is high, and the controller 40 can be understood as the control entity of the air source steam heat pump system.

[0028] Specifically, during periods when the grid load is low and the electricity price is relatively cheap, the controller 40 starts the heat pump 20 to absorb heat from the environment, and transfers the heat to the steam generation module 10 by circulating the heating medium. At the same time, the controller 40 also starts the molten salt energy storage module, and uses electric energy to heat the molten salt to a high temperature state to store heat. During periods when the grid load is too high or the electricity price is high, the controller 40 shuts down the heat pump 20 or reduces its operating power to reduce the load on the grid. At this time, the molten salt energy storage module releases the stored heat and provides thermal energy to the steam generation module 10 to meet the steam demand.

[0029] The air source steam heat pump system with molten salt heat storage provided by the embodiment of the present invention provides heat energy to the steam generation module 10 through the heat pump 20 and / or the molten salt energy storage module. During the period when the grid load is low and the electricity price is relatively cheap, the heat pump 20 is used to supply heat and the molten salt energy storage module is used to store energy. When the grid load is too high or the electricity price is high, the molten salt energy storage module stores energy and releases heat, thereby avoiding the cost increase caused by power rationing or peak-valley electricity, ensuring the stable supply of steam under power rationing, and improving the flexibility and stability of the system.

[0030] Optional, such as Figure 2 As shown, the heat pump 20 includes at least one stage of sub-heat pump, and the sub-heat pump includes an evaporator 21, a compressor 22, a condenser 23 and an expansion valve 24 connected in sequence; the evaporator 21 absorbs heat from the environment through a heat exchange process; the compressor 22 is connected between the outlet of the evaporator 21 and the inlet of the condenser 23, and is used to compress the heat absorbed by the evaporator 21 and the low-temperature and low-pressure steam generated by the evaporation process into high-temperature and high-pressure steam; the condenser 23 is connected between the outlet of the compressor 22 and the inlet of the expansion valve 24, and is used to release the heat in the high-temperature and high-pressure steam output by the compressor 22 to the outside through a heat exchange process; the expansion valve 24 is connected between the outlet of the condenser 23 and the inlet of the evaporator 21, and is used to reduce the temperature and pressure of the steam so as to reabsorb heat in the evaporator 21.

[0031] Among them, the evaporator 21 can be understood as the low-temperature end of the heat pump 20 that absorbs heat from the environment through a heat exchange process (such as absorbing heat by evaporating the low-temperature and low-pressure refrigerant); the compressor 22 can be understood as a device in the heat pump 20 that compresses the low-temperature and low-pressure steam in the evaporator 21 into high-temperature and high-pressure steam by compressing the gas to increase the thermal energy of the refrigerant; the condenser 23 can be understood as the high-temperature end that releases heat to the outside through a heat exchange process (such as releasing heat by liquefying the high-temperature and high-pressure refrigerant); the expansion valve 24 can be understood as a device for reducing the temperature and pressure of the refrigerant.

[0032] Specifically, Figure 3As shown, the operation process of the heat pump 20 can be summarized as a cycle of evaporation process, compression process, condensation process and expansion process. First, in the evaporator 21, the low-temperature and low-pressure refrigerant absorbs heat from the surrounding environment. In this process, the refrigerant is converted from liquid to gas. Subsequently, the refrigerant gas is sucked into the compressor 22 and compressed into high-temperature and high-pressure steam. In this process, the temperature, pressure and thermal energy of the refrigerant increase. Next, after the high-temperature and high-pressure refrigerant vapor enters the condenser 23, the heat is released to the steam generation module 10 through the heat exchange process. In this process, the refrigerant changes from gas to liquid. Finally, after the liquid refrigerant passes through the expansion valve 24, the refrigerant returns to a condition suitable for evaporation. In addition, an injection enthalpy increase system is introduced, and an economizer 60 is added at the outlet of the condenser 23 to separate a part of the refrigerant and send it to a special compressor with an auxiliary air intake port for air replenishment compression. The rest of the refrigerant continues to circulate according to the original main loop. The "air replenishment and enthalpy increase" can improve the heating performance of the heat pump system and reduce energy consumption.

[0033] Optional, such as Figure 3 As shown, the heat pump 20 includes a primary heat pump and a secondary heat pump; the primary heat pump includes an evaporator 21 of the primary heat pump, a compressor 22 of the primary heat pump, a condenser 23 of the primary heat pump and an expansion valve 24 of the primary heat pump connected in sequence, and the condenser 23 of the primary heat pump in the primary heat pump is directly connected to the evaporator 21 of the secondary heat pump or connected through a heat exchanger, so that the heat released in the condenser 23 of the primary heat pump is used as a heat source for the evaporator 21 of the secondary heat pump; the secondary heat pump includes an evaporator 21 of the secondary heat pump, a compressor 22 of the secondary heat pump, a condenser 23 of the secondary heat pump and an expansion valve 24 of the secondary heat pump connected in sequence, and the condenser 23 of the secondary heat pump provides heat to the steam generating module 10 through a heat exchanger or a direct connection.

[0034] Among them, the primary heat pump can be understood as the preliminary heat energy conversion part of the heat pump system, which has a complete heat pump cycle for extracting heat from a low-temperature environment: the secondary heat pump can be understood as the advanced heat energy conversion part that is structurally the same as the primary heat pump and is used to further extract the heat released in the condenser 23 of the primary heat pump to meet the heat energy demand at higher temperatures.

[0035] Specifically, when the ambient temperature is low, if only one stage of heat pump is used, the water entering the steam generation module 10 may not be heated to a sufficient temperature due to the limitation of the thermal properties of the refrigerant, and thus high-quality steam cannot be generated. Therefore, by connecting the multi-stage heat pumps 20 in series, each stage of heat pump can extract heat from the low-temperature heat source to achieve a higher temperature heat output.

[0036] For example, Figure 3As shown, the condenser 23 of the primary heat pump and the evaporator 21 of the secondary heat pump can be arranged in the same heat exchanger, the condenser 23 of the primary heat pump is the heat release end of the heat exchanger, and the evaporator 21 of the secondary heat pump is the heat absorption end of the heat exchanger.

[0037] Optional, such as Figure 3 As shown, the molten salt energy storage module 30 includes: a molten salt energy storage tank 31, which is used to store high-temperature molten salt as a heat energy carrier; a heater 32, which is arranged inside the molten salt energy storage tank 31, and is used to heat the molten salt to a predetermined temperature, or maintain the molten salt temperature; a circulating pump 33, which is connected to the molten salt energy storage tank 31 through an input pipeline, and is used to drive the heating working medium to output the heat energy stored in the molten salt energy storage module 30 to the outside.

[0038] The heating medium may be understood as water or other fluids, which are used to circulate in the system to output the stored heat energy.

[0039] Specifically, during the period of low electricity consumption, the heater 32 heats the molten salt to a predetermined temperature, converting electrical energy into thermal energy for storage; during power cuts or peak electricity consumption periods, the circulating pump 33 controls the heating medium to exchange heat with the molten salt, and then uses the gaseous heating medium steam to heat the water entering the steam generating module 10.

[0040] Optional, such as Figure 3 As shown, the steam generation module 10 includes a flash tank, which is used to flash the softened water heated by the heat pump 20 and / or the molten salt energy storage module 30 to form micro-pressure steam.

[0041] Among them, when the steam generation module includes a flash tank, the steam generation module should also adaptively include components such as a pressure reducing valve 51 and a water supply system. The water supply system is used to provide softened water; the pressure reducing valve 51 is used to reduce the pressure of high-temperature and high-pressure hot water to lower its boiling point and enter the flash tank. At this time, the fluid temperature is higher than the boiling point under this pressure. The fluid is rapidly vaporized in the flash tank to form micro-pressure steam and undergo two-phase separation. The flash tank is used to provide space for rapid fluid vaporization and vapor-liquid separation.

[0042] Specifically, when the softened water in the water supply system is heated to a predetermined temperature by the heat pump 20 and / or the molten salt energy storage module 30, the high-temperature and high-pressure hot water is decompressed by the pressure reducing valve 51 to reduce its boiling point and enter the flash tank. At this time, the fluid temperature is higher than the boiling point under the pressure. The fluid is rapidly vaporized in the flash tank to form micro-pressure steam, and two-phase separation is performed.

[0043] Optional, such as Figure 3 As shown, the steam generating module 10 further includes a first output channel and / or a second output channel; the first output channel is connected to the flash tank for directly outputting low-pressure steam; the second output channel is connected to the flash tank and is provided with a compressor 22 for pressurizing the low-pressure steam and outputting high-pressure steam.

[0044] Specifically, when the softened water is flashed in the flash tank to form micro-pressure steam, for some situations where the steam pressure requirement is not high, the valve corresponding to the first channel is opened and the steam is output through the first output channel. For situations where high-pressure steam is required, the valve corresponding to the second channel is opened and the steam is pressurized by the compressor 22 and output through the second output channel.

[0045] Optional, such as Figure 3 As shown, the steam heat pump system also includes a temperature regulation system, which includes a heat exchange medium pump 52, a medium inlet valve 53, a first heat exchanger 54, a second heat exchanger 55, a heat exchange valve 56 and a temperature sensor 57; the temperature sensor 57 is used to obtain the output temperature of the heat pump 20; the heat exchange medium pump 52 is used to drive the circulation of the heat exchange medium in the system; the medium inlet valve 53 is used to regulate the flow of the external heat exchange medium into the temperature regulation system to meet different heat exchange requirements; the first heat exchanger 54 is used to adjust the output temperature of the heat pump 20 by exchanging heat with the circulating heat exchange medium; the second heat exchanger 55 is used to heat the heat exchange medium with the heat source medium; the heat exchange valve 56 is used to close when the output temperature of the heat pump 20 is higher than the first temperature, so that the heat exchange medium reduces the output temperature of the heat pump 20 through the first heat exchanger 54; and open when the output temperature of the heat pump 20 is lower than the second temperature, so that the heat exchange medium is heated through the second heat exchanger 55 and then increases the output temperature of the heat pump 20 through the first heat exchanger.

[0046] The heat exchange medium can be understood as a thermal medium used to adjust the output temperature of the heat pump 20; the heat source medium can be understood as a thermal medium used to heat the heat exchange medium, and the thermal medium can be water or other fluid medium with a higher specific heat capacity, which is not limited in the embodiment of the present invention. The first temperature can be understood as the maximum temperature suitable for heating the soft water flowing into the steam generation module 10, and the second temperature can be understood as the minimum temperature corresponding to the first temperature and suitable for heating the soft water flowing into the steam generation module 10.

[0047] Specifically, the temperature of the thermal medium output by the heat pump 20 is confirmed by a temperature sensor 51 arranged in front of the water inlet of the steam generation module 10. If the temperature of the thermal medium is lower than the temperature range suitable for generating steam, the heat exchange medium is heated by the heat source medium (such as the thermal fluid output by the molten salt energy storage module 30), the temperature of the heat exchange medium increases, and the heat exchange medium releases heat to the heat pump 20 through the first heat exchanger 54, thereby increasing the output temperature of the heat pump 20; if the temperature of the thermal medium is higher than the temperature range suitable for generating steam, it may affect the steam quality or the flash evaporation equipment itself, so a heat exchange medium with a lower temperature is introduced to reduce the output temperature of the heat pump 20.

[0048] In addition, if Figure 3As shown, when the molten salt energy storage module 30 is used to supply heat to the steam generation module 10 and the second heat exchanger 55 at the same time, the one-way valve 80 is used to prevent the heat exchange medium in the supplementary heat cycle from entering the steam heating cycle. In the embodiments of the present invention, the various structural components mentioned, such as valves, heat exchangers, etc., are designed and selected based on the basic principle of satisfying their respective required functions. In practical applications, the specific forms, models, specifications, etc. of these structures do not need to strictly follow the descriptions or examples in the embodiments of the present invention.

[0049] Optional, such as Figure 3 As shown, the heat pump 20 , the molten salt energy storage module 30 and the steam generation module 10 perform heat exchange through the three-channel heat exchanger 70 , and the heat pump 20 and / or the molten salt energy storage module 30 in the three-channel heat exchanger 70 provide heat to the steam generation module 10 .

[0050] The three-channel heat exchanger 70 may be understood as a heat exchanger that not only includes conventional low-temperature and high-temperature channels, but also has an additional heat exchanger for temperature adjustment / switching of a heat source channel.

[0051] Specifically, the steam generating module 10 is heated by the heat pump 20 and the molten salt energy storage module 30 according to the peak and valley electricity periods. When the peak / valley electricity period is switched, the heat source switching can be completed by switching the heating channel. When the outside temperature is too low and the heat pump 20 does not provide sufficient heat, the corresponding channels of the heat pump 20 and the molten salt energy storage module 30 are both connected with thermal media to provide heat at the same time.

[0052] Figure 4 A flow chart of a control method for an air source steam heat pump with molten salt heat storage provided in an embodiment of the present invention is provided. This method is implemented based on the steam heat pump system with molten salt heat storage in the above embodiment. Figure 4 As shown, the method includes:

[0053] S110. During the off-peak period of electricity consumption, the molten salt energy storage module is controlled to heat the molten salt energy storage.

[0054] Specifically, during periods when the grid load is low and electricity prices are relatively cheap, the controller starts the molten salt energy storage module and uses electrical energy to heat the molten salt to a high temperature to store heat.

[0055] S120. During a period of low electricity consumption, control the heat pump to absorb heat from the environment to provide heat to the steam generation module, so that the steam generation module converts water into water vapor.

[0056] Specifically, during periods when the grid load is low and electricity prices are relatively cheap, the controller starts the heat pump to absorb heat from the environment and transfers the heat to the steam generation module through circulating heating medium.

[0057] S130. During power cuts or peak hours, the heat pump is controlled to stop working, and the molten salt energy storage module is controlled to provide heat to the steam generation module, so that the steam generation module converts water into water vapor.

[0058] Specifically, during periods when the grid load is too high or the electricity price is high, the controller shuts down the heat pump, starts the circulation pump of the molten salt energy storage module, and the high-temperature molten salt enters the heat exchanger 70 through the circulation pump 33 to heat the softened water in the steam generation module to meet the steam generation demand.

[0059] The embodiment of the present invention first controls the molten salt energy storage module to heat the molten salt energy storage during the off-peak period of electricity consumption, and then turns off the heat pump during power restriction or peak period of electricity consumption, and switches the molten salt energy storage module to provide heat to the steam generation module, thereby avoiding the cost increase caused by power restriction or peak-valley electricity, ensuring the stable supply of steam under power restriction, and improving the flexibility and stability of the system.

[0060] Figure 5 A schematic diagram of a control method for an air source steam heat pump with molten salt heat storage provided by an embodiment of the present invention, referring to Figure 5 , the steam heat pump system and the control method thereof are refined or optimized based on the above-mentioned embodiment. Specifically, the above-mentioned steam heat pump system also includes a temperature regulation system, which includes a temperature sensor, a heat exchange medium pump, a medium inlet valve, a first heat exchanger, a second heat exchanger and a heat exchange valve. During the low-power period, the heat pump is controlled to absorb heat from the environment to provide heat to the steam generation module so that the steam generation module converts water into water vapor. At the same time, it also includes: obtaining the output temperature of the heat pump through the temperature sensor; when the output temperature of the heat pump is higher than the first temperature, closing the heat exchange valve so that the heat exchange medium passes through the first heat exchanger to reduce the output temperature of the heat pump; when the output temperature of the heat pump is lower than the second temperature, opening the heat exchange valve so that the heat exchange medium passes through the second heat exchanger to increase the temperature of the heat pump output through the first heat exchanger.

[0061] For details not yet provided in this embodiment, please refer to the previous embodiment.

[0062] like Figure 5 As shown, another control method of an air source steam heat pump with molten salt heat storage provided by an embodiment of the present invention includes the following steps:

[0063] S210: During the off-peak period of electricity consumption, the molten salt energy storage module is controlled to heat the molten salt energy storage.

[0064] S211. Obtain the output temperature of the heat pump through a temperature sensor.

[0065] Specifically, the controller measures and obtains the current output temperature of the heat pump in real time through a temperature sensor installed at the output end of the heat pump to ensure that it operates within a set temperature range.

[0066] S212: When the output temperature of the heat pump is higher than the first temperature, close the heat exchange valve to allow the heat exchange medium to pass through the first heat exchanger to reduce the output temperature of the heat pump.

[0067] Specifically, when the heat pump output temperature obtained by the temperature sensor at the heat pump output end is higher than the preset first temperature threshold, the heat exchange valve is controlled to close and the heat exchange medium is no longer heated. At this time, the heat exchange medium cools the heat pump output end through the first heat exchanger.

[0068] S213. When the output temperature of the heat pump is lower than the second temperature, the heat exchange valve is opened to allow the heat exchange medium to pass through the second heat exchanger to increase its temperature and then pass through the first heat exchanger to increase the output temperature of the heat pump.

[0069] Specifically, when the heat pump output temperature obtained by the temperature sensor at the heat pump output end is lower than the preset second temperature threshold, the heat exchange valve is controlled to open, the heat exchange medium is heated in the second heat exchanger, and the heat exchange medium supplements heat to the heat pump output through the first heat exchanger.

[0070] S220. During the off-peak period of electricity consumption, control the heat pump to absorb heat from the environment to provide heat to the steam generation module, so that the steam generation module converts water into water vapor.

[0071] S230. During power cuts or peak hours, the heat pump is controlled to stop working, and the molten salt energy storage module is controlled to provide heat to the steam generation module, so that the steam generation module converts water into water vapor.

[0072] The embodiment of the present invention obtains the output temperature of the heat pump in real time through the temperature sensor, accurately controls the working state of the heat pump, and ensures that the output temperature of the heat pump is within the set range. When the output temperature of the heat pump is too high or too low, the heat pump output is regulated by heat exchange media of different temperatures, thereby improving the working efficiency and stability of the heat pump.

[0073] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0074] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A steam heat pump system with molten salt heat storage, characterized in that: include: A steam generation module for converting water into steam; A heat pump, used to absorb heat from the environment during the off-peak period of electricity consumption and output heat to the steam generation module; The molten salt energy storage module is used to heat the molten salt energy storage during the off-peak period of electricity consumption; and to provide heat to the steam generation module during the power cut or peak period of electricity consumption; A controller is electrically connected to the heat pump and the molten salt energy storage module, respectively, and is used to control the heat pump and the molten salt energy storage module to provide heat to the steam generation module.

2. The steam heat pump system according to claim 1, characterized in that: The heat pump comprises at least one stage of sub-heat pump, and the sub-heat pump comprises an evaporator, a compressor, a condenser and an expansion valve connected in sequence; The evaporator absorbs heat from the environment through a heat exchange process; The compressor is connected between the outlet of the evaporator and the inlet of the condenser, and is used to compress the heat absorbed by the evaporator and the low-temperature and low-pressure steam generated by the evaporation process into high-temperature and high-pressure steam; The condenser is connected between the outlet of the compressor and the inlet of the expansion valve, and is used to release the heat in the high-temperature and high-pressure steam output by the compressor to the outside through a heat exchange process; The expansion valve is connected between the outlet of the condenser and the inlet of the evaporator for reducing the temperature and pressure of the steam so as to reabsorb heat in the evaporator.

3. The steam heat pump system according to claim 2, characterized in that: The heat pump comprises a primary heat pump and a secondary heat pump; The primary heat pump comprises an evaporator of the primary heat pump, a compressor of the primary heat pump, a condenser of the primary heat pump and an expansion valve of the primary heat pump which are connected in sequence. The condenser of the primary heat pump in the primary heat pump is directly connected to the evaporator of the secondary heat pump or is connected through a heat exchanger so that the heat released in the condenser of the primary heat pump is used as a heat source for the evaporator of the secondary heat pump. The secondary heat pump comprises an evaporator of the secondary heat pump, a compressor of the secondary heat pump, a condenser of the secondary heat pump and an expansion valve of the secondary heat pump which are connected in sequence. The condenser of the secondary heat pump provides heat to the steam generation module through a heat exchanger or a direct connection.

4. The steam heat pump system according to claim 1, characterized in that: The molten salt energy storage module comprises: Molten salt energy storage tank, used to store high-temperature molten salt as a thermal energy carrier; A heater is arranged inside the molten salt energy storage tank and is used to heat the molten salt to a predetermined temperature or maintain the temperature of the molten salt; The circulation pump is connected to the molten salt energy storage tank through an input pipeline, and is used to drive the heating medium to output the heat energy stored in the molten salt energy storage module to the outside.

5. The steam heat pump system according to claim 1, characterized in that: The steam generation module comprises a flash tank, which is used to flash the softened water heated by the heat pump and / or the molten salt energy storage module to form micro-pressure steam.

6. The steam heat pump system according to claim 5, characterized in that: The steam generation module further comprises a first output channel and / or a second output channel; The first output channel is in communication with the flash tank and is used to directly output low-pressure steam; The second output channel is in communication with the flash tank and is provided with a compressor for pressurizing low-pressure steam and then outputting high-pressure steam.

7. The steam heat pump system according to claim 1, characterized in that: The steam heat pump system further comprises a temperature regulating system, which comprises a temperature sensor, a heat exchange medium pump, a medium inlet valve, a first heat exchanger, a second heat exchanger and a heat exchange valve; The temperature sensor is used to obtain the output temperature of the heat pump; The heat exchange medium pump is used to drive the circulation of the heat exchange medium in the system; The medium inlet valve is used to regulate the flow rate of the external heat exchange medium entering the temperature control system to meet different heat exchange requirements; The first heat exchanger is used to adjust the output temperature of the heat pump by exchanging heat with the circulating heat exchange medium; The second heat exchanger is used to heat the heat exchange medium using a heat source medium; The heat exchange valve is used to close when the output temperature of the heat pump is higher than the first temperature, so that the heat exchange medium can reduce the output temperature of the heat pump through the first heat exchanger; and open when the output temperature of the heat pump is lower than the second temperature, so that the heat exchange medium can be heated up through the second heat exchanger and then through the first heat exchanger to increase the output temperature of the heat pump.

8. The steam heat pump system according to claim 1, characterized in that: The heat pump, the molten salt energy storage module and the steam generation module perform heat exchange through a three-channel heat exchanger, and the heat pump and / or the molten salt energy storage module in the three-channel heat exchanger provide heat to the steam generation module.

9. A steam heat pump control method with molten salt heat storage, characterized in that: Based on the steam heat pump system with molten salt heat storage according to any one of claims 1 to 8, the method comprises: During the off-peak period of electricity consumption, the heat pump is controlled to absorb heat from the environment to provide heat to the steam generation module, so that the steam generation module converts water into water vapor; During the off-peak period of electricity consumption, controlling the molten salt energy storage module to heat the molten salt energy storage; During power cuts or peak hours, the heat pump is controlled to stop working, and the molten salt energy storage module is controlled to provide heat to the steam generation module, so that the steam generation module converts water into water vapor.

10. A steam heat pump control method with molten salt thermal storage according to claim 9, characterized in that: The steam heat pump system further comprises a temperature regulating system, which comprises a temperature sensor, a heat exchange medium pump, a medium inlet valve, a first heat exchanger, a second heat exchanger and a heat exchange valve; During the off-peak period of electricity consumption, the heat pump is controlled to absorb heat from the environment to provide heat to the steam generation module, so that the steam generation module converts water into water vapor, and also includes: Acquiring the output temperature of the heat pump by means of the temperature sensor; When the output temperature of the heat pump is higher than the first temperature, closing the heat exchange valve so that the heat exchange medium passes through the first heat exchanger to reduce the output temperature of the heat pump; When the output temperature of the heat pump is lower than the second temperature, the heat exchange valve is opened to allow the heat exchange medium to pass through the second heat exchanger to increase its temperature and then pass through the first heat exchanger to increase the output temperature of the heat pump.

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